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GEHIBW:

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

Class

BUT WHEN IT CAME TO THE VERY IMPORTANT

VAULT LIGHT CONSTRUCTION WHERE ULTRA
STRENGTH WAS ESSENTIAL TO INSURE AGAINST
ENDANGERING HUMAN LIFE BELOW, MORE THAN
LABORATORY TESTS WERE DEMANDED.

CHIEF ENGINEER PARSONS AND HIS CORPS
INSISTED MOST WISELY UPON A PRACTICAL
"TEST TO DESTRUCTION."

AFTER PROBABLY THE MOST CAREFUL TEST
EVER CONDUCTED, ALSENS WAS SELECTED FOR
USE IN ALL STATIONS, FROM THE BATTERY TO
THE BRONX: AND ATA HIGHER PRICE THAN ANY

OTHER BRAND. ON ACCOUNT OF ITS PROVEN SU-

PERIORITY AND KNOWN SAFETY.

PARTICULARS OF THIS PUBLIC TEST IN THE
LEADING ENGINEERING PAPERS OF SEPTEMBER.
1901, ARE SENT ANYWHERE ON REQUEST.

ON A "RELATIVE ECONOMY" BASIS, ALSENS IS
POSITIVELY CHEAPEST. WE PROVE OUR CLAIM!
YOU HAVE ALWAYS KNOWN ALSENS!

SIDEWALKS .nd CEMENT BLOCKS

There's a 'Reason."

MANUFACTURED
SPECIALLY FOR

Artificial Stone
Sidewalks,
Floors and
Terazzo

SPECIFIED
EXCLUSIVELY FOR

Artificial Stone,
Stucco, Tile,

Mosaic, Floors
and Sidewalks

HIGHEST TEST ABSOLUTE UNIFORMITY

CAPACITY, 7,5OO,OOO BBLS. PER ANNUM

NEW YORK RAPID TRANSIT SUBWAY STATION.
Concrete Stairways and Platforms, Turner Construction Co. ; Paving:, Vulcanite Paving: Co.

Finished Cement Conjtruction throughout entire tunnel done
Exclusively tut'th Vulcanite "Portland Cement

VULCANITE

OEM E NT

IS A SPEOIAL HIGH GRADE OF PORTLAND
Peculiarly Adapted to the Finer Uses of Cement.
Only One Brand and Grade Manufactured.

VULCANITE PORTLAND CEMENT CO.

Land Title Bide., Philadelphia. Main Sales Office, Flatiron Bid?., New \'ork
ALBERT MOYEB, Manager of Sales.

The Standard American Brand

$- PORTLAND <

ATLAS

ALWAYS UNIFORM

Output for 1905 Over 30COO Barrels Daily

Msvnvife-ctvjred by

The Atlas Portland Cement Co.

30 BROAD ST., NEW YORK

SEND for

HAND-BOOK

FOR

CEMENT USERS

THIRD EDITION REVISED AND ENLARGED

EDITED BY

CHARLES CARROLL ^ROWN

M. AM. SOC. C. E.

PUBLISHED BY

MUNICIPAL ENGINEERING COMPANY

INDIANAPOLIS, IND.
NEW YORK, N.Y.

1905

MUNICIPAL ENGINEERING
COMPANY

CONTENTS

PREFACE 9

INTRODUCTION 11

THE MANUFACTURE OF PORTLAND CEMENT 28

TESTING OF CEMENT 44

SPECIFICATIONS FOR CEMENT 74

/THE USES OF CEMENT 121

SPECIFICATIONS FOR THE USE OF CEMENT 226

DATA FOR ESTIMATES OF CEMENT WORK 334

LIME AND PLASTER 350

INDEX. . . 367

- x*r\ * R A ^^v

f Of THE ^^.

PREFACE. (UNIVERSITY)

^*uro9.^>^

The publication of the first edition of the Directory of
American Cement Industries and Hand- Book for Cement
Users in 1901, was the direct result of the many demands for
information upon all subjects connected with the manufacture,
sale and use of cement which have been made upon Muni-
pal Engineering Magazine, and of the conclusion, drawn from
close observation, that the time had arrived for the publica-
of a book giving, more particularly from the practical and
commercial standpoints, the answers to all the classes of ques-
tions which those interested in cement are asking. The instant
success of the book proved the correctness of this conclusion.
A new edition was called for in 1902, and it was much larger
and more complete than the first edition. The rapid increase
in the cement trades since 1900 shows in the greatly increased
number of names in the directory sections, and when the third
edition of the Directory of American Cement Industries was
called for in 1904, it became so large that a separation was made
and the third edition of the Directory was published without
the Hand-Book. An extra edition of the Hand-Book section of
the second edition of the combined book was published and
bound separately, and has been sold as the Hand-Book for Ce-
ment Users. On account of this extra number the third edi-
tion of the Hand-Book was not called for until the end of 1904.
Advantage is taken of this opportunity to rewrite those por-
tions of the book in which progress has been made and espe-
cially to add a full statement of the use of concrete in buildings,
in solid and hollow concrete walls, in hollow cement building
blocks, in floors and in various forms of reinforced concrete
construction. The latter treatment is extended to bridges,
arches, culverts, etc., in amplification of and addition to what
has appeared in early editions.

The introductory chapter is revised in view of the great
advances in the cement trade and in the uses to which cement is
put. A review of these advances makes a considerable addi-
tion to the chapter.

10 HANDBOOK FOR CEMENT USERS.

In the chapters on testing cement, on specifications for
cement and for its use, on the uses of cement and on testing
laboratories, additions have been made to cover the latest de-
velopments in the technical societies, in the use of cement in
public and private work, large and small, and the best new
things in specifications and descriptions of methods. Some
illustrations in the form of reproductions of drawings and
photographs are added. While these pictures are not essen-
tials, they aid in giving clearness to descriptions and fixing
them in the memory.

A new chapter is inserted upon the manufacture of cement,
giving a paper by a prominent manufacturer, with descriptions
of the various methods and machinery in use in this country.

The general features of each chapter, with the above excep-
tions, are the same as in the first edition, and may be stated as
follows :

The chapter on the uses of cement is not small, but it is not
complete. The extension of the use of cement has been so
rapid in the last few years that it is difficult to keep pace with
it. The chapter tries to confine itself to such uses as have
stood the test of time and is believed to fill the field it attempts
to cover satisfactorily. It will be still further extended in
future as may seem desirable.

The chapter on specifications gives samples of standard
specifications for the various uses of cement which are known
to give satisfaction. Variations with conditions of climate,
soil, materials, etc., are shown in the difference in specifica-
tions. The author and the locality for which the specifica-
tion is made are given whenever it seemed desirable.

INTRODUCTION.

The province of a Hand-Book for Cement Users is to supply
for its readers practical information regarding the selection
and use of cements. Theoretical considerations of the mater-
ials and methods of manufacture of cement and of the chemical
changes which take place in setting are to be found in several
other books, and are not of great interest to the practical
worker in cement. The space which they would take is de-
voted to much more intimate detail of practical specifications
and methods of work than will be found in other books on
cement.

One of the first questions which arises is that of definitions
or classification of cements. The following is as close a classi-
fication as is necessary in ordinary practice.

Those cements which are produced by burning a natural
cement rock directly are all in the class of natural hydraulic
cements. In such districts as Kosendale and Louisville, and
in such cases as Utica, Akron, Milwaukee, Fort Scott, etc.,
where the name of the district is a distinguishing mark, it is
added to the name of the brand.

In some cases, notably some of the factories is the Kosen-
dale district, some selection and mixture of rocks of
somewhat different composition is made, without the care
and expense incident to regular chemical analysis to insure
absolute uniformity and maximum quality of product. These
are classed as natural hydraulic cements.

In the Lehigh region it is a common practice to improve
the quality of the natural cement manufactured by adding
to it inferior portions of the product of the Portland cement
departments, or a proportion of the regular Portland cement
where the uniformity in quality of the rotary kiln product
obtains. This produces an "Improved" brand. Some of the
works in the same region place upon the market second and
third grades of Portland cement, some of which are made from
the inferior portions of the clinker produced by the kilns and
some mixtures of a portion of natural hydraulic cement with

12 HANDBOOK FOR CEMENT USERS.

the product of the Portland cement process. If marketed
under the name of Portland cement they will be found in that
list, although adulterated. The manufacturers turning out
these brands are usually careful to distinguish between them
in their advertising literature. Practice has changed some-
what and some factories formerly marketing several brands
have reduced their regular product to one or two brands of
Portland cement, not including the natural cements they may
manufacture.

Perhaps the only definition of Portland cement which will
fit all the American brands marketed under that name is the
following: A Portland cement is made from an artificial
mixture of materials containing lime, silica and alumina in
proper proportions. With a very few exceptions, which are
distinguished wherever necessary in this book by the word
(puzzolan) in parenthesis, this definition may be restricted
profitably by adding the requirement that the mixture shall
be made by finely grinding the materials together and shall
then be burned to a hard clinker at a high temperature.
With this restriction all the American cements which have
been considered as belonging to this class are included under
the definition, and also those which, made from slag and lime,
are treated by the Portland cement process of mixing, cal-
cining and grinding. It is is now conceded by nearly
every expert that these "calcined slag" cements may
be classed as Portland cements. The definitions of Portland
and puzzolan cements recommended by a commission of engi-
neer officers of the United States Army have been accepted
as the standard definitions and on the whole the most satis-
factory practical statements of the differences which have
been formulated. The board consists of Maj. Wm. L. Mar-
shall, Maj. Wm. H. Bixby and Capt. Charles S. Riche, of the
Corps of Engineers, United States Army. The report says:

Portland cements are products obtained from the heating
or calcining up to incipient fusion of intimate mixtures,
either natural or artificial, of argillaceous with calcareous
substances, the calcined product to contain at least 1.7 times
as much lime by weight as of the materials which give the
lime its hydraulic properties, and to be finely pulverized after
said calcination, and thereafter additions or substitutions,

INTRODUCTION. 13

for the purpose only of regulating certain properties of tech-
nical importance, to be allowable to not exceeding 2 per cent,
of the calcined product; otherwise additions or substitutions
after calcination are adulterations, necessitating a change of
name.

Puzzolan cements are products obtained by intimately and
mechanically mixing, without subsequent calcination, pow-
dered hydrates of lime with natural or artificial materials,
which generally do not harden under water when alone, but
do so when mixed with hydrates of lime (similar materials
being puzzolan, santorin earth, trass obtained from volcanic
tufa, furnace slag, burnt clay, etc.), the mixed product being
ground to extreme fineness.

The Corps of Engineers, United States Army, also defines
natural cement as one made by calcining natural rock at a
heat below incipient fusion, and grinding the product to
powder.

The definition for Portland cement adopted by the Inter-
national Union for Testing Engineering Materials is in accord
with that given above. It is :

Portland cement is a definite designation for a hydraulic
cement produced by burning an intimate natural or artificial
mixture of lime with clay or other materials which contain
silicates enough for combination and afterward grinding to
powder, and mixtures of Portland cement with other ma-
terials are not included under the term Portland cement.

Rock from which to make natural hydraulic cement is said
to have been first discovered in this country by Canvass
White in 1818, when an engineer on the construction of the
Erie canal. As hydraulic cement was needed on other canals,
other deposits were found at Rosendale, N. Y., about 1823;
Lockport, N. Y., 1824; Louisville, Ky., 1829; Cumberland and
Round Top, Md., 1836 ; Utica, 111., 1838, and later in Virginia
and the Lehigh Valley district of Pennsylvania. Hydraulic
cement was first made at Akron, N. Y., in 1840; Fort Scott,
Kas., in 1868, at Milwaukee in 1875.

14 HANDBOOK FOR CEMENT USERS.

The development of the natural cement industry is indi-
cated by the following statements of the amounts manufac-
tured in various years:

Year. No. of Works. Product. Value in cts. a bbl.

1880 2,030,000 bbl#.

1885 4,100,000 "

1890 7.082,204 ' 51.37

1895 67 7,741,077 " 50.32

1900 76 8,383,519 " 44.48

1901 6U 7,084,823 " 43.14

1902 62 8.044,305 " 50.68

1903 65 6,930,271 " 52.28

1904 4,866,331 " 50.35

The general distribution of the natural cement industry over
the country and the variation in price in different districts is
shown by the following table for 1903 :

State No. of Work*. No. of Barreli. Value.

Georgia 2 80,620 $ 44,402

Illinois 3 543,132 178,900

Indiana and Kentucky 15 1,533,573 766,786

^Kansas 2 226,293 169.155

Maryland 4 269,957 138,619

^Minnesota 2 175,000 78,750

Nebraska 1

New York 20 2,416,137 1,510,529

North Dakota 1 . . .

^Ohio 2 67,025 46,776

Pennsylvania 7 1,339,090 576,269

Texas 2

Virginia 2 47,922 25,961

West Virginia 1

Wisconsin 2 330,522 139,373

a Includes product of Nebraska and Texas.
b Includes product of North Dakota.
c Includes product of West Virginia.

The usual process in making natural hydraulic cement
is to reduce the rock to kiln size by crusher or otherwise, and
burn it in a continuous vertical kiln, into which it is fed in
alternate layers with the coal or coke used as fuel. The
product is taken out cold at the bottom of the kiln, run
through crusher and cracker, and then ground between buhr
stones, the fine material being separated and that refused by
the screens returned to the stones for further grinding. But
slight variations from this program are made, variations in
plants being mainly in details of handling. Three or four nat-
ural cement plants have installed Portland cement grinding
machinery. The ordinary product of the natural cement kiln
is not burned so hard as is necessary with Portland cement,

INTRODUCTION. 15

so that the stone mills are ordinarily able to grind the clinker
satisfactorily.

The materials used for making Portland cement are quite
various. In the Lehigh region and those of the same geological
horizon two kinds of rock are used. One is an argillaceous
limestone making a good quality of natural hydraulic cement
when burned in the ordinary kiln. The composition of this
rock is very uniform in the deposits which are used for cement
making and the beds are very deep, in some cases approximat-
ing 300 feet. To this rock there must be added a certain pro-
portion of limestone, approximately 20 per cent., to produce
the proper mixture to stand the high heat of the kilns and pro-
duce a true Portland cement. These materials are mixed and
ground, the composition of the two kinds of stone being
watched very closely that necessary changes may be made in
the proportions. There is an occasional deposit of cement
rock which is so near the correct composition and so uniform
that but one kind is used. Gradual reduction by rock crush-
ers, crackers and mill stones, Griffin mills, or ball and tube
mills, is the rule.

The powdered stone from the grinding mills is moistened
being dried thoroughly by hot air. There are a few modified
and made into bricks when burned in vertical kilns, the bricks
Shofer, Johnson, and Dietzsch continuous kilns in use and a
very few dome kilns. When the latter kiln is used the cold
kiln is filled with alternate layers of the bricks of slurry and
the coal or coke used as fuel. The kiln is then ignited and
kept burning until the fuel is consumed. The amount of fuel
to produce the proper degree of calcination must be deter-
mined before hand. When the kiln has had time to cool, the
clinker is taken out, carefully sorted and the good material
sent to the crusher. Counting the time for sorting and cool-
ing the kiln, the capacity of the intermittent kiln is about 25
barrels of cement a day when well managed, and it requires
fuel amounting to 25 per cent, or more of the weight of
cement produced. The continuous vertical kilns for burning
Portland cement must be capable of attaining a much higher
temperature than the ordinary lime or natural cement kiln.
The various patterns produce the same effect in somewhat

16 HANDBOOK FOR CEMENT USERS.

similar manner to the Shofer kiln. It is three stories in
height. The slurry bricks are put into the kiln on the upper
floor through charging doors at the foot of the stack. The
heat arising from the combustion below thoroughly dries the
bricks and heats them. The fuel is put in through stoke
holes on the floor below, and may be of the cheaper kinds
of coal. The combustion takes place in a section of the shaft
which is very much less in cross section than either above or
below, that the draft may be concentrated and the heat as
intense as necessary. The clinker is removed below from
an enlarged section of the kiln, and as it is removed the
material above drops down, thus making the action of the
kiln continuous. The draft of air for the fire being through
the hot clinker, serves to cool that material and itself be-
comes heated and thus aids combustion. These kilns are
economical of fuel, requiring about 12 per cent, of the weight
of the cement product in coal. They may be run as high as
75 barrels of cement a day. The product is more uniform
than with the intermittent kiln, but still requires careful
selection, as the process is not absolutely under the constant
control of the operator.

The rotary kiln was invented in England, but was made
successful in this country. In the Lehigh region the pow-
dered stone, having been thoroughly dried before grinding, is
fed into the upper end of the rotary kiln, which is a steel
cylinder, lined as necessary, about 6 feet in diameter aixd
from 50 to 75 feet long, depending somewhat upon the form
of the material to be burned, revolving slowly. It is set on
a slight incline so that the raw material gradually runs to
the lower end. Powdered coal is now almost exclusively used
as fuel, unless natural gas is available, being forced under
pressure into the lower end, where it burns at the point of
entrance. The force of blast, amount of fuel, and rate
of rotation of the cylinder being under the instantaneous
control of the operator, the character of the product depends
entirely upon his attention to the work, and practically every
particle of the resulting clinker makes the highest
grade of cement of which the material is capable. The
rotary kiln burns in fuel a little more than one-third the

INTRODUCTION. 17

weight of the cement produced, and kilns are made capable
of turning out 100 to 150 or even 200 barrels of cement a day.
The effect of this kiln upon the development of the cement
industry is considered later.

The tendency is toward longer kilns, especially in the wet
process mills, described below, which must evaporate the large
quantities of water used in making the mixture, and they will
be found of various lengths, even exceeding 100 feet in a few in-
stances. One kiln in a dry process mill is 150 feet long and
is served with fuel by two or three feeder tubes under different
air pressures, so that the combustion zone is extended for a
greater distance along the kiln. This largely increases the
capacity of the kiln, claims of 1,000 barrels a day being made.

The clinker may be run through crushers and crackers, if
large enough to need it. That from rotary kilns is, however,
so small, say the size of peas or a little larger, that this is not
necessary. A few mills use buhr-stones for grinding, but
most Portland cement clinker is too hard to grind economi-
cally in this manner. The Griffin mill, an American invention,
consists of a steel ring, against the inside surface of w,hich
a heavy steel roll revolving on a vertical shaft presses by
centrifugal force. A separator drops the fine material into
conveyors for transfer to the stock rooms and returns the
coarser material to the mill for further grinding. Other mills
on similar principle but differing materially in design are en-
tering the field. The ball mill is approximately a cylinder
partly filled with steel balls or round pebbles of very hard
stone and arranged with screens for separating the fine
product and returning the coarse product to the mill. It was
originally used in the same manner as the other mills men-
tioned, but is now generally used as a first reducer, the ma-
terial, when it is reduced to the required size, passing to a
tube mill, which has a continuous cylindrical surface and is
much longer. The material passes slowly from one end of the
mill to the other. The size of the particles of clinker fed to the
tube mill, the amount of pebbles with which it is charged, the
rate of rotation and the length of the tube are variable quan-
tites, the resulting design in- any particular case giving a uni-
form fineness of product. The 'crushed clinker from the ball

18 HANDBOOK FOR CEMENT USERS.

mill is fed into the tube mill through the axis at the upper
end and drops out at the circumference or the axis as desired at
the lower end. If the mill is properly designed, a separator
to return partly ground material is not necessary. There are
also closed pebble mills into which the material to be ground is
introduced in charges, each charge being run a definite length
of time, as determined by experience. The finely ground ma-
terial is then removed and a new charge put in. With any of
the apparatus mentioned any desired degree of fineness can be
secured. The particular apparatus to be used, and the length
of time the material must be retained, depend upon the hard-
ness of the material, the fineness desired and the cost of
operation allowable.

In some factories the raw materials are limestone and clay
or shale, which may be treated by the dry or the semi-wet
processes already described.

In most of the factories of Ohio, Indiana and Michigan the
wet process of mixing the materials or some modification of
it is used. The marl is excavated from the lake or marsh at
the bottom of which it has been deposited by nature and
is pumped or otherwise conveyed to a bin or basin in the fac-
tory. The clay or shale is brought in from the bank and the
two materials are mixed in edge runner mills with water
enough to allow the mixture to flow into another basin and
be pumped through wet grinding mills, and kept moving in
tanks, where it is analyzed and the mixture corrected.
Thenec the wet material is pumped into the upper end of
rotary kilns similar to those mentioned above, dropping out
at the lower end as well burned Portland cement clinker.
The process of mixing varies somewhat in different mills, but
is in principle that followed in the best European plants.

One or two factories in this country use chalk and clay.

The manufacture of a cement from blast furnace slag is a
recent development in this country. Several factories are now
taking the slag from furnaces using suitable ore, cooling it
suddenly with water and mixing the resulting slag sand with
limestone or lime. The materials are thoroughly dried and
mixed and then pulverized and fad to a rotary kiln according
to the dry process. The resulting clinker is ground and pro-

INTRODUCTION. 19

duces a cement with similar constituents and characteristics
and made by a similar process to other American Portland
cements, so that it can not be excluded by definition of pro-
cess or product from the list of Portland cements.

Several factories are producing a cement properly classed
as puzzolan by mixing blast furnace slag, prepared as de-
scribed, with slaked lime and grinding to the desired fineness.
Although often sold under the name of Portland cement and
available for many of the same processes, it is not a true
Portland cement according to the accepted definitions given.
The spelling of the word puzzolan has been changed from that
used in the first edition of this book, for, although the form poz-
zuolana shows its derivation most clearly, the adoption of the
shorter form by the Corps of Engineers, United States Army,
and by prominent manufacturers, as well as the .tendency of
our language toward the shortest forms possible, makes the lat-
ter the more desirable.

A few factories are making cement by a special process con-
sisting in the intimate mixture of dry sand and cement fol-
lowed by very fine grinding, so that the result is an impalpa-
ble powder composed of cement and sand. Tests of proper
materials, very finely ground, show some surprisingly high re-
sults for tensile strength, and briquettes on long time tests
sometimes show higher results than the neat cement from
which the mixture was made. These cements are called silica
cements. The tendency to cheapen the cement is observed in
some of these brands as in other brands of Portland cement,
but there are a few brands of silica Portland cements which
have a deservedly high reputation for strength and uniform-
ity, especially in tests of mortar briquettes.

A short statement of the principal reasons for the enor-
mous development of the American cement industry may be
of interest. It is largely due to two causes. One is the in-
crease of density of population and the consequent increase
in the amount of work in which cement has long been used
and in the great extension in the number of uses to which
cement can be put; and the other is the development of labor-
saving processes for manufacture which reduce the cost, so
that cement can be used for many constructions from which

20 HANDBOOK FOR CEMENT USERS.

it has been largely excluded on account of the relative cheap-
ness of other materials.

The intermittent vertical kiln, similar to the lime kiln, was
first used in burning natural cement, perhaps as early as
1823, in this country. It was soon followed by the continuous
kiln, of similar type, but with more than double the capacity,
because no time was lost in cooling the calcined material and
recharging and refiring the kiln. The comparatively low tem-
perature in these kilns is sufficient for the calcination of the
natural cement rock; in fact, a higher temperature injures
the product from some deposits of cement rock.

The Portland cement industry developed in other countries,
notably in England, France and Germany, using chalk or
limestone and clay as materials. Intermittent kilns like the
dome kilns, continuous kilns like the Dietzsch, and ring kilns
like the Hoffman, were used, the high temperature necessary
for complete calcination of the exact mixture necessary for
Portland cement being obtainable in the special combustion
chambers or by the methods of charging and burning. With
the very best of care, however, it was impossible to secure
uniform calcination of all the products of the furnace, and
very careful selection of clinker was necessary that the
cement be uniform. This necessitated much hand labor with
a certain expertness, and with the vast amount of labor
necessary in making bricks, drying them and depositing them
in the kiln and the many handlings between, made a total
which, under American conditions of labor, insured a price
too high to compete with cement produced with the cheaper
labor of Europe.

Notwithstanding this and the entire difference in materials,
Mr. D. O. Saylor conceived the idea of making Portland
cement by European methods, modified to make them fit the
materials he had, viz. : the natural cement rock of the Lehigh
region and limestone. After years of experimenting he suc-
ceeded in making a high grade of Portland cement by mixing
the two kinds of rock in proper proportions, and by intro-
ducing labor saving devices and improved machinery was able
to compete in the American market with foreign cements,
with some help from the tariff, except where the prejudice in

INTRODUCTION. 21

favor of foreign cement at any price could not be overcome.

Ten years after Mr. Saylor made his first Portland cement
Ransome patented in England and the United States the
rotary kiln, using gas for fuel, but with the small kilns used
and the previous treatment of raw material it was a failure.
The Atlas Portland Cement Company took up the kiln, and
with the more favorable hard and dry materials of the Lehigh
Valley, finally made a success of it. Crude oil was later
introduced for fuel, which is now almost entirely displaced by
finely powdered coal.

Mention should be made of earlier use of the kiln with
reasonable success by Duryee and Sanderson at Montezuma
and Wallkill, N. Y., in works which are not now in operation,
owing to excessive cost of raw materials in one case and to de-
struction of the works by fire in the other.

With the success of this kiln the development of the Port-
land cement industry in this country began in earnest. It is
possible to carry the material from the raw material cars to
the finished package of cement without any handling, and this
great reduction in the cost of labor enables the American
manufacturer to compete successfully in price with any coun-
try in the world.

In 1892 the Warner Portland Cement Company tried the
perfected kiln upon wet slurry, obtained by the mixture of
marl and clay in pug mills, instead of drying and pulverizing
bricks made of it and attempting to calcine this dust accord-
ing to the method which failed in England. This was success-
ful, and the development of the manufacture of cement in
northern Ohio and Indiana and in Michigan is due to this
process, the wet material fed in at one end of a rotary kiln
coming out at the other perfectly calcined Portland cement
clinker of the size of peas. The Sandusky Portland Cement
Works, under the management of the Newberrys, are respon-
sible for much of the progress made toward technical perfec-
tion in cement manufacture.

One feature of the rotary kiln process is the absolute uni-
formity with which the clinker can be calcined. The intro-
duction of variable speed apparatus puts the kilns under the
absolute control of the expert in charge of them, and he can

22 HANDBOOK FOR CEMENT USERS.

determine exactly the rate and amount of calcination the
material shall receive.

The capacity of the rotary kilns in use averages about 125
barrels a day, say six times the capacity of the old intermit-
tent kiln. They require more than twice the fuel of the
continuous vertical kiln per barrel of product, so that there
is some offset to the saving in labor cost.

Another branch of the process in which there has been
great improvement is the grinding of clinker and, where
required, of the dry raw materials. There are two general
classes of mills; those in which the fine dust is separated
from the partly ground material, the latter being returned to
the mills; and those in which the process is continued long
enough to turn out the finished product of any desired degree
of fineness.

The amount and the rapidity of the development of the
manufacture of Portland cement in the United States are
indicated by the following figures from the reports of the
United States Geological Survey :

Year. No. of Works. Product, Barrels. Value. *

1880 82,000

1885 150,000

1890 16 355,500 $ 704,050

1895 22 990324 1,586,830

1900 50 8,482,020 9,280,525

1901 56 12,711,225 12,532,360

1902 65 17,230,644 20,864,078

1903 78 22,342,973 27,713,319

1904 26,505,881 23,355,119

*The value includes packages in 1900. Later figures give value
in bulk.

INTRODUCTION.

The distribution of the manufacture of Portland cement
and the development in the various regions is shown in the
following table :

1890

1894

1900

1903

District.

No.
of
W's

Prod't
Bbls

Per

Ct.

No.
of
W's

Prod't
Bbls

Per

Ct.

No.
of
W's

Prod't
Bbls

Per

Ct.

No.
of

W's

Prod't
Bbls.

Per
Ct.

New York

65,000, 19.4

117,275

14.7

465,832

5.5

1,602,846

7.2

Lhigrh and North- )
ampton Go's Pa. /
& Warren Co. N.J.I

201,090

60.0

485,329

60.8

6,153,629

72.6

12,324,922

55.2

Ohio

22,000

6.5

80,653

10.1

534 215

729 519

3 3

664 750

1 955 183

8 7

All Other Sections.

47,500

14.1

115,500

14.4

663,594

7.8

5,730,403

25.6

TOTAL,

335,500

100.0

798,757

100.0

8,482,020

100.0

22.342,973

100

The principal materials used are the mixtures of cement
rock or clay and limestone and the mixtures of clay and marl.

All the new factories have installed rotary kilns. The
amount of cement made in other kinds of kilns has been
reduced somewhat by closing of some such kilns and the re-
placing of others by rotary kilns. The complete displacement
of all other kilns is but a question of a comparatively short
time, with the exception, perhaps, of a very few special cases.

Puzzolan or slag cement in 1903 was made in seven plants in
six states, Alabama having two plants under one management,
and Illinois, Maryland, New Jersey, Ohio and Pennsylvania one
each. Another plant in Ohio began operations in 1904. There
are several other plants using slag and limestone for making
a true Portland cement.

The expansion in the use of cement and the fact that cement
is in reality a cheap material for its weight and bulk, increase
the tendency toward localization of the industry and the new
plants are using the best materials they can find, without much
reference to whether they are two kinds of stone, stone and clay,
marl and clay, etc. Since 1899, Alabama, Colorado, Georgia,

HANDBOOK FOR CEMENT USERS.

Indiana, Kansas, Missouri, Texas, Virginia and West Virginia
have been added to the list of states in which Portland cement
is manufactured, and New Mexico and North Dakota have been
taken off. Neither of these states should have been on the list,
for the New Mexico plant makes plaster and the North Dakota
plant makes natural hydraulic cement. In the same time the
number of works in California has increased from 1 to 3; in
Illinois from 2 to 5 ; in Michigan from 4 to 13 ; in New Jersey
from 2 to 3; in New York from 7 to 12; in Ohio from 6 to 8;
in Pennsylvania from 9 to 17.

The increase in the manufacture of cement in the various
states from 1899 to 1903 is shown in the following table :

PRODUCTION OF PORTLAND CEMENT IN THE UNITED STATES

IN 1899 AND 1903:

1899

1903

State.

No. of

works

Product.

Value, not
including:
packages.

No. of
works,

Product.

Value, not
including:
packages.

Alabama

Barrels

* 1

Barrels

Arkansas. .-.

50,000

$87,500

* 1

California. . . .

60,000

120,000

631, is 1

$1 019,352

Colorado

* 1

258,773

436,535

Georgia

* 2

Illinois

53,000

79,500

1,257 500

1,914 500

Indiana ........

1,077,137

1,347,797

Kansas

* 1

1,019,682

1,285,310

Michigan

342,566

513,849

1,955,183

2,674,780

Missouri

* 2

825,257

1,164,834

New Jersey
New York

892.167
472,386

1,338,250
708,579

3
12

2,693,381
1,602,946

2,941,604
2,031,310

Ohio

480,982

721,473

729,519

998,300

Pennsylvania. . .
South Dakota. .

9
1

3,217,965
35,000

4,290,620
70,000

17
1

9,754,313

11,205,892

Texas

Utah

45, 000

135,000

538,131

690, 105

West Virginia..

Total

5,652,266

8,074,371

22,342,673

27,713,319

* In 1903 the production for Alabama, Georgia, Virginia and West
Virginia is combined under Virginia, and is a clear gain of five plants over
1899, since none of these States had plants in operation in the earlier
year. Arkansas and Missouri are combined under Missouri in 1903, so
that the one plant of 1899 with 50,000 barrels capacity has expanded to
3 plants with 825, 2p7 production. Kansas and Texas are combined under
Kansas, a clear gain of three plants over 1899. Utah, South Dakota and
Colorado are combined under Colorado and show a gain of one plant
over 1899.

INTRODUCTION.

The following table, giving the total consumption of
cement in the United States, will also be of interest, showing
at it does the development in each case of the classes of cement
reported and the effects 'of the changes in conditions upon the
cement trade. The per cent, of the total cement used during
the year for each kind is also given. The percentages have
been computed from the quantities given in reports of the
United States Geological Survey and the Bureau of Statistics
of the Department of Commerce and Labor. The figures for
imported Portland and for domestic Portland are corrected for
the amounts re-exported and exported, respectively, for the
last three years, thus showing the actual consumption of cement
in the United States. Exports prior to 1901 and puzzolan
manufacture prior to 1899 were small enough to be neglected.

TOTAL CONSUMPTION OF CEMENT IN THE UNITED STATES IN

BARRELS AND ANNUAL PERCENTAGES OF EACH

CLASS REPORTED.

Year.

Natural
Hydraulic.

Per Ct.
for Yr-

Imported
Portland.

Per Ct.
for Yr.

Domestic
Portland.

Per Ct.
for Yr.

Puzzolan.

Per Ct.
for Yr.

To 1880

54,970,000

98.4

793,281

82,000

1880

2,030,001

89.9

187,000

42,000

1.8

1881

2,440,000

89.7

221.000

8.1

60,000

2.2

]882

3,165,000

87.4

370,406

10.2

85,000

2.4

1883

4,190,000

87.9

486,418

10.2

90,000

1.9

1884

4,000,000

85.4

585.768

12.5

100,000

2.1

1885

4,100,000

85.4

554', 396

11.5

150,000

3.1

1886

4,186,152

84.0

650,032

13.0

150,000

3.0

1887

6,692,744

83.5

1,070,400

13.4

250,000

3.1

1888

6,253,295

75.0

1,835,504

22.0

250,000

3.0

1889

6,531,876

76.2

1,740,356

20.3

300,000

1890

7,082,204

75.7

1,940,186

20.7

335,000

3.6

1891

7,451,535

68.4

2,988,313

27.4

454,813

4.2

1892

8,211,181

73.3

2,440,654

21.8

547,44d

4.9

1893

7,411,815

69.5

2,674,149

25.0

590,652

5.5

1894

7,563,488

68.7

2,638,107

24.0

798,757

7.3

1895

7,741,077

66.0

2,907,395

25.6

990,324

8.4

1896

7,970,450

63.7

2,989,697

23.9

1,543,023

12.4

1897

8,311,688

63.5

2,090,924

160

2,677,776

20.5

1898

8,418,724

59.6

2,043,818

14.3

3,692,284

26.1

1899

9,868,179

55.3

2,108,388

11.8

5,652,266

31.6

233,000

1.3

1900

8,383,519

42.7

2,386,683

12.2

8,482,020

43.2

365,611

1.9

1901

7,084,823

34.4

893,444

4.3

12,337,291

60.0

272,689

1.3

1902

8,044,305

29.5

1,926,704

7.0

16,889,823

61.8

478,555

1.7

1903

6,930,271

21 8

2,225,272

7.0

22,057,510

69.5

525,896

1.7

1904

4,866,331

15.2

1.059,666

3.3

25,730,941

80.5

305,045

0.9

The data in this table are shown graphically in the accom-

HANDBOOK FOR CEMENT USERS.

panying diagram. ' The vertical ordinates represent the per-
centages of each cement used in a year, computed on the basis
of the total amount of the four classes used in a year, and the
diagram represents these percentages for each year from 1880
to 1903.

DIAGRAM SHOWING CHANGES IN PERCENTAGES OF THREE CLASSES OF
CEMENT USED EACH YEAR FROM 1880 TO 1903:

The following table shows the increase in consumption of
cement per capita of population. It is computed from the
preceding table of total consumption of cement in the United
States, assuming 380 pounds as the net weight of Portland
cement, 280 pounds as the average net weight of hydraulic
cement, east and west, and 330 pounds as the net weight of
puzzolan. This may be compared with the statement that in
1900 the average production of Portland cement in Germany,
was 135 pounds per capita:

CONSUMPTION OF CEMENT IN THE UNITED STATES.

Per Capita of Population.

Year.

Population.

Consumption in Pounds Per Capita,

Portland Cement.

All Kinds of Cement.

1880
1890
1900
1904

50,155,783
62,622,260
75,559,258
80,734,061*

1.7
13.8
54.7
126.1

13.1
45.5
87.3
1443

Estimated.

INTRODUCTION. 27

The exportation of cement is increasing with modifications
caused mainly by the differences in ratio of home supply and
demand. The exports for 1896 were 85,486 barrels; for 1900,
139,939 barrels; in 1902, 375,130; in 1903, 312,160; and in 1904,
774,940. In each case these figures include domestic cement
exported and foreign cement re-exported.

The following data regarding average product of each mill
and average value per barrel at the mill, will be of interest.
The table to 1901; is taken from Municipal Engineering, Vol.
XXIV, page 83 ; the figures for 1902 and 1903 being added as
Computed from the cement reports for those years made by the
United States Geological Survey. In computing the daily
product from the annual product, the operating year is assumed
as 300 days :

AVERAGE PRODUCT PER MILL AND AVERAGE VALUE OF PORTLAND
CEMENT AT MILL.

Average Product Average Value in

of each Mill. bulk, per Barrel

Year. Barrels pr day. at Mill

J895 150 $1.60

1896 197 1.57

1897 308 1.61

1898 397 1.62

1899 523 1.43

1900 565 1.09

1901 757 .99

1902 912 1.21

1903 955 1.24

It is probable that the number of mills in operation in 1904
has been no greater than the number in 1903 and that the av-
erage production per mill is somewhat greater. The value
per barrel at the mill was but 88 cents during 1904.

In Canada in 1904 the output of natural hydraulic cement
decreased to 56,814 barrels as compared with 92,252 barrels
in 1903. In 1904, 908,990 barrels of Portland cement were
manufactured, a material increase over 1903. The imports of
cement were 784,630 barrels of 350 pounds in 1904, the value
being |1,061,056. The United States supplied more than half
of this or |510,718 worth.

THE MANUFACTURE OF PORTLAND
CEMENT.

The following from a paper before tne International Engi-
neering Congress at St. Louis, Mo., in October, 1904, by Robert
W. Lesley, Assoc. Am. Soc. C. E., is a clear description of the
principal methods of manufacturing Portland cement and of
the principal kinds of machinery used therein :

Power. Economies in this field are at the root of the whole
business, and all modern mills for the production of Portland
cement depend largely upon cheapness in the production of
the power operating the machinery.

To produce cement properly at a reasonable cost, mills must
have large capacity and turn out many thousands of barrels per
day. This can only be done with the most improved steam-pro-
ducing machinery and the most economical method of distri-
buting the power throughout the plant. An examination of
cement mills, the world over,- will disclose the fact that, in all
those of large size in successful operation, the steam plant
represents the highest development of power-producing ma-
chinery.

Power must be produced in the most economical way, and no
form of economical steam production can be neglected; if the
manufacturer desires to keep pace with his rival. Boilers of
the most improved character, and engines of. the most modern
form are to be found in cement mills of the kind described.

Coupled with all these developments is the simplest form of
distributing the power. The present period marks the intro-
duction of large and powerful shafting, driven with the short-
est length of belting, or rope drives, directly from the engines,
and transmitting the power to crusher mills, kilns and other
parts of the machinery with the least possible friction.

Further than this, the great development of electricity has
enabled numerous companies to operate much of, and in many
cases all, their machinery by independent motors of various
kinds. This is very successful where the water power is near
the mill, as is the case with some of the Michigan mills, and
is also likely to be the case with some of the European mills
to be constructed in Switzerland and northern Italy. It is also
practicable where cheap power may be obtained by the use of
waste from iron furnaces, as is the case with the new works
which the Illinois Steel Company is building at Buffington,

THE MANUFACTURE OF PORTLAND CEMENT. 29

near near Chicago, 111. At this plant waste heat from the iron
furnaces is to be used to produce power, which, in turn, is
changed to electricity and transmitted by heavy cables, over the
Calumet river, some eight miles to the new works.

There is considerable discussion among the leading manufac-
turers and experts as to the relative cost of the electrical power
produced by steam and steam power, though the general opin-
ion is in favor of the latter; it being considered that, while
single motors, driving single machines, enable kilns and mills
to be thrown in and out of gear with greater economy than
where belting is used, yet this advantage does not over-balance
the greater cost of production of electricity, even though in
the former method the loss of power by friction in shafting
and belts is admitted as a disadvantage.

Raw Materials. The raw materials for cement making in-
clude the great number of substances containing lime, silica
and alumina. Consequently, they may be said to exist the
world over, but the successful establishment of a Portland
cement plants depends, not only upon the raw materials, but
upon their juxtaposition to each other and to proper fuels, and
upon proper railway facilities for the distribution of the pro-
duct to the markets where it is to be consumed.

Limestones, argillaceous limestones, cement rocks, and marl,
are among the cement-making materials, and all may be said
to contain the lime element. To all these, except the cement
rocks, silica and alumina, in the form of clay or shale, are
added to produce the argillaceous or clayey requirements,
while, to the cement rocks, additional lime is added to bring
the material up to the proper lime limit.

Every mill has, for its basic proposition, the proper govern-
ing of these raw materials, and their proper preparation for
calcination. At this point occurs the first dividing line in the
industry. The manufacturer must produce the material for
calcination from either wet or dry mixtures. If the raw mater-
ial is a marl, or a substance of that character, he will add clay
or shale to bring it up to the proper and required argillaceous
composition. As the lime material is wet, the mixture of clay
in this slurry will be a wet one. This position, governed by the
selection of raw materials for manufacture, must govern the
first process, namely, the preparation of the raw materials
for the kilns; and this selection will govern the machinery
for all the processes, up to the introduction of the wet slurry,
or composition, into the kiln, whether dome kilns, continuous
kilns, ringofen or rotary kilns are used.

Mining the Raw Materials. The kind of raw materials,
either dry or wet, having been decided, the problem now pre-

30 HANDBOOK FOR CEMENT USERS.

sented to the manufacturer is to procure and deliver it at the
place for its preparation. In the case of marl and clays, there
are many methods in use. Marls, where semi-dry, may be ex-
cavated by hand labor or steam shovels. The material is car-
ried to the "raw" or "composition" side of the cement mill in
barrows or carts. Where the material is very wet marl, as in
many of the Michigan and Indiana plants, where it lies at
the bottom of lakes, it is excavated by dredges. Clays are ex-
cavated either by steam shovels or by hand.

Rocks and shales are mined in open quarries or in tunnels.
Most of the cement quarries are open-faced, and the methods are
those used in ordinary limestone quarries. Steam, compressed
air, or electric drills are used for making the holes preparatory
to blasting, and, in most operations, the material is delivered
at the composition side of the mills by cars or carts. In some
of the more modern mining operations steam shovels are sub-
stituted for ordinary labor, and the rock, as it is blasted, is
picked up and conveyed by the steam shovels to cars or carts;
but this is practicable only when the material is very uniform
in analysis. In mining the limestone requisite to bring cement
rocks up to proper composition, the practice is similar.

Shale is mined either in accordance with the practice of deal-
ing with clays, where the material is soft, or is handled or
mined by processes similar to those used in quarrying limestone
when the shale is hard.

At this stage the elements of vital importance consist in
procuring only materials of proper character, and in classify-
ing them properly, as well as in developing the most economical
methods of mining the raw materials and delivering them to
the mixers or dryers.

Preparation of the Raw Materials. In modern practice it
is considered not only necessary to have continuous analyses
of the cement rocks, limestones, marls, clays, etc., made as they
are being mined, but also to have at the plant, on the compo-
sition side, sufficient quantities of materials on hand to check
up these analyses, and also to have stock to meet any unex-
pected break-down in the mining machinery, or delays caused
by storms or other reasons. Therefore, stone storage build-
ings are found in connection with the most modern mills, and
in some cases these edifices are warmed by waste heat, so that
the external moisture upon the stones or clays may be expelled
even before the drying process.

Drying the Raw Materials. After assembling the materials,
the line of demarcation between wet and dry processes becomes
fixed. Wet substances, clay and marl, are handled in the con-
dition in which they come from the marl beds or clay pits, and,

THE MANUFACTURE OF PORTLAND CEMENT. 31

after being proportioned by weight, are run into mixers of
various forms, as described later. In some cases it has been
found advisable to add the clay to the marl at a later stage in
the process, and in this case it is dried in rotary dryers of
various forms, such as the Cummer dryer, Ruggles-Coles Com-
pany dryer, Mosser dryer, or similar apparatus. The general
principle is that of a long cylinder, which revolves in a chamber
of brick at one end, wherein a coal fire is placed. In this case
the clay, when dry, is pulverized and introduced into the wet
marl by weight, in exact proportions, in order that the mixture
may be combined properly.

Dry material, limestones and cement rocks, are first crushed
in the well-known forms of Gates gyratory crushers, or in Blake
crushers, in which they are reduced to small pieces.

After this operation, the crushed material is placed in dryers
in order to eliminate any surface moisture or moisture con-
tained in the rock. In general practice, the mixture of the dry
materials takes place at the crusher mouth, and at this point
is placed a furnace scale, with a number of beams, set to weigh
the various ingredients. After weighing the material it is
placed in a crusher, in which a preliminary mix takes place.
A variation from this process is found in certain works, where
the two materials are mixed at a later stage in the process,
namely, after they are ground raw, and in this case they are
brought together in a powdered form, after weighing and
proportioning by any of the well-known forms of automatic
weighing apparatus.

Wet materials are generally mixed by weight, and, except
where clay in the dry form is added, this takes place before the
first grinding.

Crushing and Grinding the Raw Materials. In the case of
wet raw materials, practice varies, both in the United States
and in Europe, depending upon the character of the substances.
If the rnarl and clay are free from grit, sand or shells, they can
be mixed intimately in pug mills, or wash mills, and the
mixture stored in a very wet condition in tanks. When the
materials contain grit, or shells, modern practice requires wet
grinding, usually by mills of the ordinary buhr-stone type.
Numerous forms of these have been in use. Revolving pans
and chasers may also be used. The character of the raw ma-
terial and its homogeneity being the governing factor in the
product, it may be stated that, even where the materials are
extremely uniform in character, modern practice prefers to
grind them, rather than trust to ordinary mixing in tanks or
pug mills, as above stated.

After the raw wet material has been prepared by any of

UNIVERSITY

32 HANDBOOK FOR CEMENT USERS.

these forms of machinery, in modern plants it is usually placed
in one of a series of tanks, having proper means for agitating
the "mix" and keeping it of the right consistency. Samples
from these tanks are analyzed, to govern the character of the
composition, and if satisfactory, it is then made into "bricks,
blocks, or other forms, where dome kilns or continuous kilns
are use; or, if rotary kilns are used, it is run into smaller tanks
above the kilns. In either case, homogenizing tanks are re-
quired, wherein the mixture may be run if not of satisfactory
character, and wherein it may be treated by adding and mixing
in tjie requisite ingredients.

In the case of dry materials, the preliminary grinding is one
of the most important features, especially where the material
is to be used in rotary kilns. The character of the resultant
clinker and cement depends upon the fineness of this composi-
tion, and many interesting papers have recently been pre-
sented showing the effect of this fine grinding upon the sub-
sequent action of the cement. Microscopic examinations of
the cement produced show the importance of this branch of
the manufacture.

Under the old processes, w r here wet materials were used, and
even where dry materials were pugged and wetted to put them
in plastic form for moulding, much was claimed for the greater
value of the cement produced from very wet composition, and
this had some basis in the fact -that the grinding, in olden
times, was much less perfect, and many advantages were de-
rived from the action of the water upon any soluble lime or
gelatinous silica which might be free in the mixture. Very
fine grinding at the present period may be said to take the place
of this excess of water.

Therefore, in order to obtain the most intimate mixtures,
where the powder, in its dry state, is to be placed in the revolv-
ing kiln, it is necessary that the grinding should be most thor-
ough and the composition be an almost impalpable powder.
This extremely fine grinding has been found necessary to pro-
duce the highest grades of cement, and the study of manufac-
turers is largely devoted to the problem of making this impal-
pable powder ready for the kiln at the lowest cost for power
and repairs. Many forms of mills have been devised for this
purpose, and will be described later, when taking up the general
operation of grinding, as applied to the final preparation of
the impalpable powder known as Portland cement.

Generally speaking, however, the first essential is that the
rock to be ground shall be as dry as possible, in order that there
may be no delays caused by choking the screens, clogging the
mills, or otherwise interfering with the continuous process of

THE MANUFACTURE OF PORTLAND CEMENT. 33

manufacture. Forms of crushers, especially adapted to care
for the raw material as it comes from the dryers, have been in-
troduced in the United States, and embrace Buchanan rolls,
Smidth Kominuters, Mosser crushers, etc., all of which are de-
" scribed later. Important factors at this stage of the process
are heavy shafting, large reserve power, large elevators, belt-
ing, etc. In some modern mills, great judgment has been
shown in laying out this branch of the business, and in hand-
ling the raw material with the greatest efficiency; returning to
crushers and mills all material not of the required fineness,
and using every appliance to obtain the greatest efficiency at
the lowest cost.

When it is considered that, in round figures, for every barrel
of Portland cement, weighing 380 pounds, there is to be handled
in the raw-rock process actually from 600 to 650 pounds of raw
cement rock and limestone, and in the wet process actually
from 1,200 to 1,500 pounds of marl and clay, it can be seen how
rapidly money may be lost by improper installation at this
stage of the process.

The general line of thought, in modern practice, would seem
to indicate that gradual reduction is the proper process- at this
point of the manufacture, and that the day of the old buhr mills
for grinding the dry materials is completely at an end. The
forms of machinery now used are either mills like the Griffin,
Huntingdon or Kent, which are iron mills of the centrifugal
type, having a ball or balls operating upon the raw material,
or any of the forms of tube or ball mills, where the grinding is
done by the attrition of Iceland pebbles or steel balls upon the
material to be treated. The distinction between mills of these
two classes is that the latter will take care of stone of almost
any size that can be introduced through the feed hopper, while
in gyratory centrifugal mills a system of gradual reduction by
passing the material through Mosser crushers and. through
Buchanan rolls, is necessary for the greatest efficiency. It is
even now a grave question whether this efficiency would not be
further increased by additional rolls, so as to reduce the ma-
terial to still greater fineness before its entrance into the grind-
ing apparatus.

Kilns. The first kilns, as already stated, were the old bottle
or dome kilns of varying sizes, and intermittent in action. The
raw materials, either dry or wet, and in the shape of bricks
or blocks, are placed in the kilns through doors at various
heights, and covered alternately with layers of coal and coke.
When the kiln is charged to a point fairly well up in the stack
with these alternate layers of coal and coke, it is lighted at the
bottom and allowed to burn out. In this operation, the fuel

34 HANDBOOK FOR CEMENT USERS.

and carbonic ncid are burned out, the material shrinks, sinks
to the lower part of the kiln, and the bricks run together. After
the material in thoroughly cool, the mass is broken down, the
under-burned yellow, and the over-burned glazed, materials
are thrown out, and the clinker, in the shape of large lumps, is
carried to the crusher for final grinding.

In the Dietzsch, Shoefer and Hauenschild kilns, the bricks
are carried through the drying chambers to the top of the kiln,
and are fed from time to time in regular charges. A sufficient
quantity of coal is fed at the same time, and the operation is
continuous. The burning takes place in the fire-chambers in
the center of the kiln, the flame from which dries the material
in the upper part of the kiln, while the material, having passed-
the combustion zone, goes down to the lower shaft of the kiln
and is drawn therefrom at regular intervals.

In this process, as in the dome kiln, the selection of the
clinker is an important factor, the over-burned and under-
burned portions requiring to be removed.

Both these forms of kilns require much labor for the making
of bricks before placing them in the fire. The bricks of .com-
position must be quite dry before they are placed in dome
kilns, and considerable work is required in obtaining this re-
sult, as well as in charging and drawing the kiln. Further-
more, coke, which is now becoming an expensive fuel, is re-
quired for the successful operation of dome kilns.

With kilns of the second style, a cheaper form of fuel may be
used, coal of ordinary character being sufficient, but the labor
item is a large one, many men being required to keep the kilns
in continuous operation day and night. The old style of dome
kilns, which were in general use in Europe some fifteen years
ago, and were also the only kilns in operation in the United
States, may be said to be gradually sinking out of commercial
existence. The continuous kiln, however, is doing good work,
and it is used extensively in Europe and in several works in the
United States.

The cement made in these two forms of kilns differs con-
siderably in its character from that made by the rotary-kiln
process, and, where the specifications are those of moderate
tensile strains at seven and twenty-eight days, has qualities
which enable it to be used very successfully as they are pro-
duced without the addition of sulphate of lime, or plaster,
which is essential to cement as now made in the rotary-kiln
process.

During the period when the old forms of kilns were being
used, various inventions were made for the introduction of the
composition into the kilns without all -the intermediate pro-

THE MANUFACTURE OF PORTLAND CEMENT. 35

cesses of settling tanks, brickmaking, drying and rehandling.
Among these inventions were those of DeSmedt, Lesley and Will-
cox, for theintroduction of hydro-carbons, as pitch, tar, petro-
leum waste or other similar substances, into the cement paste.
The object of these inventions was to burn the raw material in
a pasty condition, without falling apart, as was the case with
compositions treated w r ith water alone. Methods for the prepa-
ration of pastes of this kind under heavy pressures, in order
that the bricks or blocks should be hard enough to bear the
weight of the superincumbent material in the kiln, were also
made at or about the same time, and while the process was used
successfully for several years, the advance in the price of pitch,
due to the introduction of water gas in the large gas-works,
doing away with the waste coal-tar, practically made the hy-
dro-carbons so costly that the process had to be abandoned.

The Rotary Kiln. The growth and development of the ce-
ment industry in the United States within the past ten years
are essentially due to the introduction of the rotary kiln. This
kiln, invented by Kansome in England some twenty years ago
and improved by Stokes, consists of an iron cylinder lined with
fire-brick. The diameter increases from 60 inches at the
chimney end to 66 inches at the discharge end. The kiln is
about 60 feet in length, supported by trunnions at two points
and trained by a pair of gears. This kiln uses as a fuel either
natural gas, oil or powdered coal, which is introduced at the
discharge end. When originally introduced in England, it
was operated by fuel gas or by oil. Inventions were also made
in the same line in the United States by Matte and Navarro.
The first of these inventors, however, confined his kiln and its
operation to the use of crushed stone, not pulverized, and his
processes were not successful. The latter' s inventions were
adapted to various improvements in the revolving kiln of Ran-
some and Matte.

In the early days of the rotary kiln, oil was always used as
fuel, though the practice of using pulverized coal in kilns of
similar construction, for calcining cement as well as other ma-
terials, had been thoroughly described in various patents in
the United States and elsewhere, and was well known.

During this period, the development of rotary-kiln cement
was very slow, because no methods had been discovered by which
the extremely quick-setting qualities of the cement could be
overcome and a safe material produced. If the composition
were kept low enough in lime to insure safety, the cement was
too quick-setting for use, and if the lime were run up to a point
high enough to make it even moderately slow setting, an imper-
fect cement would be produced and disintegration of the ma-

36 HANDBOOK FOR CEMENT USERS.

terial in briquettes and in work would sometimes ensue after
a longer or shorter time. About this time, discoveries were
made, based upon experiment in Germany, for seasoning ce-
ment, whereby the setting qualities of rotary-kiln cement were
regulated by the use of gypsum (sulphate of lime, either raw or
calcined). With this discovery, which made rotary-kiln ce-
ment a commercial product, the development of the rotary
kiln began, and has continued to the present time.

The use of powdered coal was due to the advance in the price
of oil. Lima oils were sold at nominal prices, and oil was used
successfully in the East, as it now is on the Pacific Coast, in
burning cement in rotary kilns. Natural gas is used in Kan-
sas.

Generally stated, material prepared in the wet way, is fed
into the upper end of the kiln from tanks. The kiln revolves
at the rate of from a half to one revolution per minute, and is
inclined from the stack, where the material is fed in, to the dis-
charge end. The mix gradually works its way down to a point
near the discharge end. At this point, which varies according
to the materials used and the length of the kiln, in what is
called the fire zone, the calcining of the material takes place.
The material at the upper end of the kiln gives up its carbonic
acid gas and moisture under the flame directed upon it from
the lower end.

This lower end of the kiln projects into a stationary or mov-
able hood, which forms a shield to protect the burner and reg-
ulate the admission of air. In this hood are nozzles which
supply the requisite fuel. The mechanism for feeding the
powdered coal varies in different mills. In practically every
case, however, there are nozzles, through which the pulverized
fuel is driven by blast, at either high or low pressure, regulated
by the burner. The stream of powdered coal from the nozzle
carries with it a certain quantity of air, from around the hood
or from other openings, and this supports combustion. As the
pulverized fuel strikes the heated kiln and is transformed into
gas, a series of explosions takes place. The flame goes through
the kiln, drives out the carbonic acid gas and moisture from the
material at the far end, and burns the material in the fire zone
to incipient vitrification. After calcination the material goes
to the discharge end, where it falls into elevators or conveyors,
by which it is carried to cooling towers, which are large iron
cylinders subjected to forced draft, and in which the material
as it falls is fully exposed to the cool air.

In the case of dry material, the composition is fed from
hoppers above the upper end of the kiln, and enters the latter
in the form of impalpable powder. This powder is subjected to

THE MANUFACTURE OF PORTLAND CEMENT. 37

the flame, precisely as in the case of the wet materials, and the
calcination takes place almost under the same circumstances,
the fire zone varying in its extent according to the material
under calcination.

During late years many improvements have been suggested
for the form and length of kilns, and in the pressures to be used
in calcining. Methods have also been suggested, and in many
cases put in practice, notably by Professor Carpenter, of Cor-
nell University, for the utilization of the waste heat for. driving
off larger percentages of moisture from wet materials, and also
for steam-generating purposes.

In the first case, an auxiliary kiln of the same length as the
calcining kiln has been introduced, and the flames, after tra-
versing the first 60-foot kiln, are conducted into the second
one, where they are utilized for evaporating the water from the
wet mass of clay and marl composition.

In the second case, the waste heat is taken under boilers,
where it is used to make steam for running the machinery of
the works.

Much has also been done in relation to the size and propor-
tions of the kilns. Originally, lengths of 40 feet were quite
common. This was followed by making the kilns about 60
feet long, with a diameter of 60 inches at the chimney end and
66 inches at the discharge end. The form has been adopted
very generally, and is in use in most mills.

Within the past three years, however, considerable develop-
ment has taken place in the lengthening of the kilns. The first
experimenter in this direction was Thomas A. Edison, who, in
his works, installed kilns 150 feet long; but these, owing to
difficulty in turning them and the large number of mechanical
appliances connected therewith, have not yet proven absolute
commercial successes. Between this size, however, and the 60
foot kiln in common use, there was a large margin in which
manufacturers could experiment, and several plants have kilns
from 80 up to 107 feet in length. The latter size has been
adopted recently by one of the largest plants in the United
States. In general practice, the 60 foot kiln is stated to give
about 200 barrels per day, and those who have experimented
with longer kilns claim to have reached as many as 300 barrels
per day with the 80 foot length, and from 400 to 500 barrels
per day with the 107 foot kilns. Should these experiments
prove successful, the capacity of American Portland cement
works is susceptible of very large increase at small expense.
The present coal consumption in the 60 foot kilns varies from
90 to 120 pounds per barrel, where dry material is used and
considerably more with wet material.

38 HANDBOOK FOR CEMENT USERS.

In connection with -the development of the rotary kiln,
many experiments have been conducted to determine the
amount of heat used in the kiln and that going up the stack
OP otherwise wasted. Professor Richards, of Lehigh Univer-
sity, in a paper before the Association of Portland Cement
Manufacturers, claimed that as much as 72 per cent, of the total
heat supplied was lost; and, from this, various investigations
as to the theoretical coal consumption in kilns have been made,
leading to the methods for utilizing this waste heat in various
ways. Examinations have also been made regarding the action
of the heat in the kiln upon the composition contained therein,
and the possible saving of the by-products contained in this
material. Papers on this subject, by Professor Meade, of
Easton, Pa., and by Clifford Richardson, Assoc. Am. Soc. C. E.,'
of New York City, indicate that various percentages of sul-
phuric acid, potash and soda are carried out in the fuel gases
and deposited at the base of the chimney. The utilization of
these by-products is a subject for the manufacturer to consider,
but he must also bear in mind the loss he might entail upon
himself by retarding the discharge of the gases and the conse-
quent rapidity of the calcination of the cement.

Grinding. In the past ten years there have been many im-
provements in this branch of the manufacture, and in describ-
ing grinding, as a general subject in this paper, it is intended
that much that is written shall apply, not only to grinding the
finished materials, but also to the preparation of the raw ma-
terials, as already indicated,. for the reason that most of the
machinery used in the finishing process is also used in the
preparatory process of manufacture.

Of course, the first thing to do with the clinker as it comes
from the kilns it to cool it sufficiently for proper grinding, as
it changes greatly in its characteristics and toughness, ac-
cording to the time it has been exposed to air after calcination.
At this stage of the process there come before the manufacturer
again two methods of handling the product, and, according to
which of the two he adopts, the question of crushing or not
crushing will present itself. If he decides to use the ball and
tube mills in batteries, he can feed the clinker immediately
into the ball mill, but if, on the other hand, he uses any of the
forms of gyratory centrifugal mills, such as the Griffin or Hunt-
ingdon, it will become necessary to prepare his- material by
gradual reduction to a proper size for the best operation of the
mill to be used. These forms of crushers are various; the
Mosser crusher, or coffee-mill crusher, is simply a cone re-
volving in a corrugated pan, and requires considerable power.

Other forms of crushers are the Buchanan corrugated rolls,

THE MANUFACTURE OF PORTLAND CEMENT. 39

which have large capacity, and crush by direct pressure. The
surface speed is about 1,000 feet per minute, and on the two
rolls there is a wearing surface of about 40 square feet of the
best steel, which is subject to a compressive strain only, and
does no grinding. It is a slow-speed machine, and requires few
repairs. Modern processes suggest that rolls of this kind be
used for a form of gradual reduction, to prepare the material
for Griffin, Huntingdon or Kent mills, or other mills of that
general type. Such rolls should be placed one following the
other, so that the material can be reduced to, say, about 12
mesh for Griffin mills; and if they are used as adjuncts to tube
mills the material can be reduced to about 20 mesh, thus in-
creasing the efficiency and capacity of the mill, providing great
reduction of po\ver and lessening the cost of labor.

In the various modifications in processes and apparatus
which have been made during the past ten years, in connection
with the manufacture of cement, all with the common object
of attaining greater economy in cost of production, it is doubt-
ful if in any part of the process the innovations have been more
interesting and radical than those pertaining to grinding the
materials and separating the finished product. Nor can there
be any question that in this department the most surprising
successes in the attainment of further economy have been se-
cured. The importance of this is manifest when it is consid-
ered what a material part the cost of grinding has been. The
importance of this portion of the expenditure in manufactur-
ing is due to the fact that grinding is incident almost to the
initial operation of reducing the limestone, rock and coal, and
also to the final operation of pulverizing clinker to finished
cement, and, from this standpoint, has made the cost account
ever noticeable to the manufacturer.

At the time of the Chicago World's Fair the cement industry
realized the great cost and many disadvantages incident to
attrition grinding, which up to that period had been used for
reducing the raw material and making the finished cement.
Almost every mill ground the cement and raw material by
rubbing between the upper and nether stones of a buhr mill,
and bolted the resultant product in revolving reels. The horse
power necessary to drive the buhr mills with the requisite
friction for reducing Portland cement, the wear and tear cost
and consequent labor cost of frequent recutting of the buhr
stones, together with the heavy cost of reel bolting, was so large
that the industry at that time was seeking to break away from
this handicap.

Prior to this time, in the early nineties, some headway had
been made in overcoming the cost of millstones, the first Griffin

40 HANDBOOK FOR CEMENT USERS.

mill, of the self-screening, suspended-roller type, having been
placed in the works of the American Cement Company, at
Egypt, Pa., in May, 1889. This mill is still running on nat-
ural and Portland cement clinker.

This mill utilizes in its construction the principle of a roll
running against a ring or die. Heretofore, in all mills on this
principle, the roll has been propelled by being pushed around
by drivers, or carried on journals within the roll, and the fric-
tion and destruction of the pushing devices and journals have
been great, and have involved both loss of power and excessive
wear and tear.

In the Griffin mill this difficulty is overcome by a new
mechanical movement which has not been used heretofore in
a machine of any kind. This invention obviates the use of
multiple shafts and journals in pulverizing chambers with re-
volving rolls, thus greatly reducing the wear and tear, and at
'the same time giving a greater product in proportion to the
power consumed. This movement is somewhat like that of a
tee-totum and is that of a revolving pendulum having a heavy
steel ball which strikes the inner side of a steel ring. The
grinding is done partly by the blow of the pendulum and
partly by its rubbing against the ring during its peculiar mo-
tion. The mill is supplied with screens above the grinding
ring, and carries scrapers which throw the material from the
bottom up to the higher or grinding zone. The material is
thrown out through screens as it is ground.

In practical use it secured a material reduction in the horse
power cost and in the labor account. Owing to its high speed
and great power, and grinding efficiency, there is a considerable
wear and tear account, and where the mills are not well erected
or handled, occasional break-downs occur. The introduction of
mills of this type, which represent also the Huntingdon type,
provided a most efficient substitute for the slow-going buhr
mill at the time of the introduction of this form of grinding
apparatus.

The suspended-roller type of mills represented high-speed
machinery and great improvements upon the old millstones,
and mills of this type are used extensively in the United States
and also in many parts of Europe, there being at present nearly
800 of this type in operation in the United States alone.

The difficulties, as stated previously, caused manufacturers
to look for mills of other forms, which it was hoped would
prove more reliable, and entail less wear and tear. From the
rapidly running Griffin or Huntingdon mill to the slow-rolling
ball or tube mill was a long step, but, about 1894, ball and tube
mills were adopted as substitutes for other forms of grinding
machinery.

THE MANUFACTURE OF PORTLAND CEMENT. 41

The ball mill was adopted as a breaker, for feeding to the
tube mill as a finisher. The tube mill, as already stated, was
first introduced in the United States in 1894. As is well
known, these principles are availed of in ball and tube mills,
by introducing into a revolving barrel or drum the material to
be reduced with balls or with pebbles. The mass rolls contin-
ually on itself down one side of the interior of the barrel, the
resulting impact and attrition sufficing to crush and wear down
the material until the desired fineness is obtained.

The very simplicity of the principle of reduction by ball and
tube mills was a sufficient guaranty of its reliability, and the
fact that all wear, incident to attrition between the balls and
pebbles and the cement, was carried on into the product, helped
to offset the wear and renewal account.

The ball mill is a primary apparatus in this form of grind-
ing, and was introduced in 1895, but it is a relatively expensive
machine to maintain. Its main faults are that the normal con-
tent of steel balls will grind more than the possible screen area
will pass; the balls strike upon perforations intended for the
exit of materials, and gradually close the holes, and the lining
consists of very large plates, which are difficult to handle and
costly to make and place. On the other hand, it is claimed
that it requires low horse-power in proportion to the output,
little attention, and, inasmuch as the materials passed through
it are screened to a given size, it is a satisfactory preliminary
grinder for materials destined to be pulverized in the tube mill.

In the last two years there has appeared in the market a
coarse grinder called a Kominuter, in which it has been sought
to avoid the well-known faults of the ball mill. This machine
consists of a drum, of about the length of its diameter, sus-
pened in bearings by a shaft through the heads. The entire
drum is surrounded by a coarse screen, or perforated plate,
and outside of this is the screen frame upon which is attached
the necessary wire cloth, giving an enormous screening surface.
The drum is lined with wrought iron grinding plates, arranged
in steps similar to the ball mill. The material enters beside
the shaft, travels the full length of the drum, and finds exit
through ports arranged at the outlet end. The particles which
are larger than the openings in the inside screen, or perforated
plate, are returned automatically to the center of the mill by
buckets and "S" shaped pipes. The materials passing the in-
side screen are caught on the outside screen, and the rejections
are returned to the mill in the same manner.

The tube mill operates upon the same general principles as
the ball mill, and is intended to be a finishing apparatus in this
form of grinding. There are several tube and ball mills which

42 HANDBOOK FOR CEMENT USERS.

vary but slightly in mechanical details and efficiency, and, for
practical purposes, it may be stated that the tube mill is about
the same to-day as when first brought into the Portland cement
industry in the United States.

The Kominuter is intended to be used as a preliminary
grinder for ball mills and in the ball and tube mill combination,
and it is sought to make use of each machine in the field of its
greatest economy, the object being that each mill will have its
own work in this slow-moving field of gradual reduction.

The ball mills were introduced in Germany about ten years
ago, and the general design since then has* not been altered
materially. The various forms of these mills are made by the
Kruppes Grusenwerk, F. L. Smidth & Company, and the Allis-
Chalmers Company in the United States. Batteries of ball*
and tube mills are operated together. They take the clinker
as it comes from the kilns, and grind it into the impalpable
powder known as Portland cement.

In addition to the mills already described, a new mill has
recently come into use, and is known as the Kent mill, or re-
volving ring mill, having three grinding rolls which are
mounted on horizontal shafts, and press directly against the
surface of the heavy vertical ring, on the center surface of
which the cement is fed and between which and the rolls it is
pulverized. This is a slow-running mill. The ring is revolved
at sufficient speed to utilize the centrifugal force to hold the
cement on its inner surface, thus avoiding the use of scrapers
for bringing the material into position to be crushed.

The rolls simply roll over the cement under great pressure,
and crush it to impalpable powder, without measurable fric-
tion, the action being claimed to be purely a crushing one,
distinguished from that of the ball jnill or buhr stone.

Goal Grinding. In addition to the raw materials and the
clinker which require the use of the various forms of grinding
machinery described, there is also another important use for
this machinery in modern mills using coal in the rotary-kiln
.process, and the foregoing description of the machinery applies
fully to that use the preparation of the pulverized coal for
use in the kilns. This is usually done in a separate building,
where the coal, after drying in any of the forms of dryers de-
scribed, is run through mills, generally of the gyratory charac-
ter, and reduced to impalpable powder, in which form it is in-
troduced into the kiln. This grinding is usually done in a
building separated from the rest of the plant, in order to avoid
any danger from explosion or fire. The modern construction
of these buildings provides for ample ventilation and large
head-room, thus lessening the possibility of the explosion of
finely pulverized fuel.

THE MANUFACTURE OF PORTLAND CEMENT. 43

Storehouses. After the material comes from the grinding
machine it is carried by elevators into conveyors, and by the
latter distributed through the stockhouses. These buildings,
in mills of large capacity, are immense edifices of concrete or
stone, providing storage room for hundreds of thousands of
barrels. The pulverized material is generally run into bins,
ranging in capacity from 2,000 to 5,000 barrels, thus providing
units of various sizes for testing purposes. Plans have been
made for storehouses in which the cement is to be run into
hopper-shaped bins, thus enabling the material to be run di-
rectly from the hoppers into barrels or bags, avoiding much of
the present cost of loading, in plants where the cement is run
directly to the floors of one-story warehouses.

Many methods of loading, by machines of various characters
packing cement in barrels or bags are in use, but have not
been adopted generally. One of the most important improve-
ments in stockhouse management has been the introduction of
bag-cleaning machinery, both at the mills and in the large
cities, by which bags are gathered in the cement-consuming
markets and are shaken and cleaned and the loose cement
saved, thus effecting a great economy in freight by returning
the bags to the mill in their clean condition. Similar practice
at the mills saves a considerable quantity of cement, which,
otherwise would be wasted, and also insures a better repair of
the bags and a better appearance of the packages.

TESTING OF CEMENT.

The methods of testing cement which have been considered
standard by American engineers are those adopted by the
American Society of Civil Engineers in 1885, being reconv
mended by a strong committee with full theoretical and prac-
tical knowledge of the subject. Lately it has been felt that
this report was not quite up to the advances which have been
made in the manufacture of Portland cement, and another
equally strong committee has been appointed to consider the
subject. This committee brought in a progress report in Jan-
uary, 1903, and made some modifications of the report in Jan-
uary, 1904. At the same time it reported that some points
had not yet been settled and therefore asked for a continuance.

The American Society for Testing Materials has also had a
strong committee at work upon the subject, and this commit-
tee has made a report which has been officially adopted by the
Society. It embodies much of the matter and phraseology
of the report to the American Society of Civil Engineers, and
is given in full as the only official statement of standard prac-
tice. The methods of examination recommended are given in
this chapter and the specifications will be found in the follow-
ing chapter. Following this official document will be found a
statement of such matters in the report to the American So-
ciety of Civil Engineers as were omitted from this document.

METHODS OF THE AMERICAN SOCIETY FOR TESTING MATERIALS.

General Observations. 1. These remarks have been pre-
pared with a view of pointing out the pertinent features
of the various requirements and the precautions to be observed
in the interpretation of the results of the tests.

2. The Committee would suggest that the acceptance or
rejection under these specifications be based on tests made by
an experienced person having the proper means for making the
tests.

Specific Gravity. 3. Specific gravity is useful in detecting
adulteration or underburning. The results of tests of specific
gravity are not necessarily conclusive as an indication of the
quality of a cement, but when in combination with the results
of other tests may afford valuable indications.

TESTING OF CEMENT. 45

Fineness. 4. The sieves should be kept thoroughly dry.

Time of Setting. 5. Great care should be exercised to main-
tain the test pieces under as uniform conditions as possible.
A sudden change or wide range of temperature in the room in
which tests are made, a very dry or humid atmosphere, and
other irregularities vitally affect the rate of setting.

Tensile Strength. 6. Each consumer must fix the minimum
requirements for tensile strength to suit his own conditions.
They shall, however, be within the limits stated.

Constancy of Volume. 7. The tests for constancy of volume
are divided into two classes, the first normal, the second ac-
celerated. The latter should be regarded as a precautionary
test only, and not infallible. So many conditions enter into
the making and interpreting of it that it should be used with
extreme care.

8. In making the pats the greatest care should be exercised
to avoid initial strains due to molding or to too rapid drying
out during the first twenty-four hours. The pats should be
preserved under the most uniform conditions possible, and
rapid changes of temperature should be avoided.

9. The failure to meet the requirements of the accelerated
tests need not be sufficient cause for rejection. The cement may,
however, be held for twenty-eight days, and a retest made at
the end of that period. Failure to meet the requirements at
this time should be considered sufficient cause for rejection,
although in the present state of our knowledge it can not be
said that such failure necessarily indicates unsoundness, nor
can the cement be considered entirely satisfactory because it
passes the tests.

Selection of Sample. 1. The sample shall be a fair average
of the contents of the package. It is recommended, that
where conditions permit, one barrel in every ten be sampled.

2. All samples should be passed through a sieve having
twenty meshes per linear inch, in order to break up lumps and
remove foreign material; this is also a very effective method
for mixing them together in order to obtain an average. For
determining the characteristics of a shipment of cement, the in-
dividual samples may be mixed and the average tested; where
time will permit, however, it is recommended that they be
tested separately.

Method of Sampling. 3. Cement in barrels should be sam-
pled through a hole made in the center of one of the staves,
midway between the heads, or in the head, by means of an
auger or a sampling iron similar to that used by sugar inspec-
tors. If in bags, it should be taken from surface to center.

Chemical Analysis. 4. Method As a method to be followed

46 HANDBOOK FOR CEMENT USERS.

for the analysis of cement, that proposed by the Committee on
Uniformity in the Analysis of Materials for the Portland Ce-
ment Industry, of the New York Section of the Society for
Chemical Industry, and given herein on a subsequent page, is
recommended.

Specific Gravity. 5. Apparatus and Method The determi-
nation of specific gravity is most conveniently made with
Le Chatelier's apparatus. This consists of a flask of 120 cu.
cm. (7.32 cu. ins.) capacity, the neck of which is about 20 cm.
(7.87 ins.) long; in the middle of this neck is a bulb, above and
below which are two marks; the volume between these two
marks is 20 cu. cm. (1.22 cu. ins.). The neck has a diameter
of about 9 mm. (0.35 in.), and is graduated into tenths of cubic
centimeters above the upper mark.

6. Benzine (62 degrees Baume naphtha), or kerosene free
from water, should be used in making the determination.

7. The specific gravity can be determined in two ways :

(1) The flask is filled with either of these liquids to the
lower mark,, and 64 gr. (2.25 oz.) of powder, previously dried
at 100 degrees C. (212 degrees F.) and cooled to the tempera-
ture of the liquid, is gradually introduced through a funnel
(the stem of which extends into the flask to the top of the
bulb), until the upper mark is reached. The difference in
weight between the cement remaining and the original quan-
tity (64 gr.) is the weight which has displaced 20 cu. cm.

8. (2) The whole quantity of the powder is introduced,
and the level of the liquid rises to some division of the grad-
ated neck. This reading plus 20 cu. cm. is the volume dis-
placed by 64 gr. of the powder.

9. The specific gravity is then obtained from the formula :

Weight of Cement
Specific Gravity= Disp i ace d Volume

10. The flask, during the operation, is kept immersed in wa-
ter in a jar, in order to avoid variations in the temperature
of the liquid. The results should agree within 0.01.

11. A convenient method for cleaning the apparatus is as
follows: The flask is inverted over a large vessel, preferably
a glass jar, and shaken vertically until the liquid starts to
flow freely; it is then held still in a vertical position until
empty; the remaining traces of cement can be removed in a
similar manner by pouring into the flask a small quantity of
clean liquid and repeating the operation.

Fineness. 12. Apparatus The sieve should be circular,
about 20 cm. (7.87) ins.) in diameter, 6 cm. (2.36 ins.) high,
and provided with a pan 5 cm. (1.97 ins.) deep, and a cover.

TESTING OF CEMEMT. 47

13. The wire cloth should be woven (not twilled) from brass
wire having the following diameters:

No. 100, 0.0045 in.; No. 200, 0.0024 in.

14. This cloth should be mounted on the frames without dis-
tortion; the mesh should be regular in spacing and be within
the following limits:

No. 100, 96 to 100 meshes to the linear inch.
No. 200, 188 to 200 meshes to the linear inch.

15. Fifty grams (1.76 oz.) or 100 gr. (3.52 oz.) should be
used for the test, and dried at a temperature of 100 degrees C.
(212 degrees F.) prior to sieving.

16. Method. The thoroughly dried and coarsely screened
sample is weighed and placed on the No. 200 sieve, which, with
pan and cover attached, is* held in one hand in a slightly in-
clined position, and moved forward and backward, at the same
time striking the side gently with the palm of the other hand, at
the rate of about 200 strokes per minute. The operation is
continued until not more than one-tenth of 1 per cent, passes
through after one minute of continuous sieving. The residue
is weighed, then placed on the No. 100 sieve and the opera-
tion repeated. The work may be expedited by placing, in the
sieve a small quantity of large shot. The results should be
reported to the nearest tenth of 1 per cent.

Normal Consistency. 17. Method. This can best be deter-
mined by means of the Vicat Needle Apparatus, which consists
of a frame, bearing a movable rod, with a cap at one end
and at the other a cylinder, 1 cm. (0.39 in.) in diameter, the cap,
rod and cylinder weighing 300 gr. (10.58 oz.). The rod, which
can be held in any desired position by a screw, carries an indi-
cator, which moves over a scale (graduated to centimeters) at-
tached to the frame. The paste is held by a conical, hard-
rubber ring, 7 cm. (2.76 ins.) in diameter at the base and 4 cm.
(1.57 ins.) high, resting on a glass plate about 10 cm. (3.94 ins.)
square.

18. In making the determination, the same quantity of ce-
ment as will be subsequently used for each batch in making the
briquettes (but not less than 500 grams) is kneaded into a
paste, as described in paragraph 39, and quickly formed into a
ball with the hands, completing the operation by tossing it six
times from one hand to the other, maintained 6 ins. apart ; the
ball is then pressed into the rubber ring, through the larger
opening, smoothed off, and placed (on its large end) on a glass
plate and the smaller end smoothed off with a trowel; the
paste, confined in the ring, resting on the plate, is placed under
the rod bearing the cylinder, which is brought in contact with
the surface and quickly released.

HANDBOOK FOR CEMENT USERS.

19. The paste is of normal consistency when the cylinder
penetrates to a point in the mass 10 mm. (0.39 in.) below the
top of the ring. Great care must be taken to fill the ring
exactly to the top.

20. The trial pastes are made with varying percentages of
water until the correct consistency is obtained.

NOTE. The Committee on Standard Specifications inserts
the following table for temporary use, to ~be replaced by one to
be devised by the Committee of the American Society of Civil
Engineers.

PERCENTAGE OF WATER FOR STANDARD MIXTURES.

Neat

1-1

1-2

1-3

1-4

1-5

Neat

1-1

1-2

1-3

1-4

1-5

12.0

10.0

9-0

8.4

.8.0

13.3

11.5

10.4

9.6

12.3

10.2

9.2

8.5

8.1

17.3

13.6

11.7

10.5

9.7

127

10.4

9.3

8.7

8.2

17.7

13.8

11.8

10.7

9.9

13.0

10.7

9.5

8.8

8.3

18.0

14.0

12.0

10.8

100

13.3

10.9

9.7

8.<

)

8.4

18.3

142

12.2

10.9

10.1

13.7

11.1

9.8

9.1

8.5

18.7

14.4

12.3

11.1

10.2

14.0

11.3

10.0

9.2

8.6

19.0

14.7

12.5

11.2

10.3

14.3

11.6

10.2

9.3

8.8

19.3

14.9

12.7

11.3

10.4

14.7

11.8

10.3

9.5

8 9

19.7

15.1

12.8

11.5

10.5

15.0

12.0

10.5

9.0

20.0

15.3

13.0

11.6

10.6

15.3

12.2

10.7

9.1

20.3

15.6

13.2

11.7

10.7

15.7

12.5

10.8

9.9

9.2

20.7

15.8

133

11.9

10.8

16.0

12.7

11.0

10.0

21.0

16.0

13.5

12.0

11.0

16.3

129

11.2

10.1

9.4

21.3

16.1

13.7

12.1

11.1

16.7

13.1

11.3

10.3

9.5

Ito 1

1 to 2 1 to 3 1 to 4

1 to 5

Cement,

500

333 250 200

167

Sand

500

666 750 800

833

Time of Setting. 21. Method. For this purpose the Yicat
Needle, which has already been described in paragraph 1.7,
should be used.

22. In making a test, a paste of normal consistency is
molded and placed under the rod, as described in paragraph 18 ;
this rod, bearing a cap at one end and a needle, 1 mm. (0.039
in.) in diameter, at the other, weighing 300 gr. (10.58 oz.).
The needle is then carefully brought in contact with the surface
of the paste and quickly released.

23. The setting is said to have commenced when the needle
ceases to pass a point 5 mm. (0.20 in.) above the upper surface
of the glass plate, and is said to have terminated the moment
the needle does not sink visibly into the mass.

24. The test pieces should be stored in moist air during the

TESTING OF CEMENT. 49

test ; this is accomplished by placing them on a rack over water
contained in a pan and covered with a damp cloth, the cloth
to be kept away from them by means of a wire screen ; or they
may be stored in a moist box or closet.

25. Care should be taken to keep the needle clean, as the
collection of cement on the sides of the needle retards the pene-
tration, while cement on the point reduces the area and tends
to increases the penetration.

26. The determination of time of setting is only approxi-
mate, being materially affected by the temperature of the mix-
ing water, the temperature and humidity of the air during the
test, the percentage of water used, and the amount of molding
the paste receives.

Standard Sand. 27. For the present the Committee recom-
mends the natural sand from Ottawa, 111., screened to pass a
sieve having 20 meshes per linear inch and retained on a sieve
having 30 meshes per linear inch; the wires to have diameters
of 0.0165 and 0.0112 in., respectively, i. e., half the width of the
opening in each case. Sand having passed the No. 20 sieve
shall be considered standard when not more than 1 per cent.
passes a No. 30 sieve after one minute continuous sifting of a
500-gram sample.

28. The Sandusky Portland Cement Company, of Sandusky,
Ohio, has agreed to undertake the preparation of this sand and
to furnish it at a price only sufficient to cover the actual cost
of preparation.

Form of Briquette. 29. While the form of the briquette
recommended by a former committee of the Society is not
wholly satisfactory, this Committee is not prepared to suggest
any change, other than rounding off the corners by curves of
one-half inch radius.

Molds. 30. The molds should be made of brass, bronze or
some equally non-corrodible material, having sufficient metal
in the sides to prevent spreading during molding.

31. Gang molds, which permit molding a number of bri-
quettes at one time, are preferred by many to single molds;
since the greater quantity of mortar that can be mixed tends
to produce a greater uniformity in the results.

32. The molds should be wiped with an oily cloth before
using.

Mixing. 33. All proportions should be stated by weight;
the quantity of water to be used should be stated as a percent-
age of the dry material.

34. The metric system is recommended because of the con-
venient relation of the gram and the cubic centimeter.

35. The temperature of the room and the mixing water

50 HANDBOOK FOR CEMENT USERS.

should be as near 21 degrees C. (70 degrees F.) as it is practi-
cable to maintain it.

36. The sand and cement should be thoroughly mixed dry.
The mixing should be done on some non-absorbing surface, pre-
ferably plate glass. If the mixing must be done on an absorb-
ent surface it should be thoroughly dampened prior to use.

37. The quantity of material to be mixed at one time de-
pends on the number of test pieces to be made; about 1,000 gr.
(35.28 oz.) makes a convenient quantity to mix, especially by
hand methods.

38. Method. The material is weighed and placed on the mix-
ing table, and a crater formed in the center, into which the
proper percentage of clean water is poured; the material on
the outer edge is turned into the crater by the aid of a trowel.
As soon as the water has been absorbed, which should not re-
quire more than one minute, the operation is completed by vig-
orously kneading with the hands for an additional iy 2
minutes, the process being similar to that used in kneading
dough. A sand-glass affords a convenient guide for the time of
kneading. During the operation of mixing, the hands should
be protected by gloves, preferably of rubber.

Molding. 39. Having worked the paste or mortar to the
proper consistency, it is at once placed in the molds by hand.

40. Method. The molds should be filled at once, the mater-
ial pressed in firmly with the fingers and smoothed off with a
trowel without ramming; the material should be heaped up on
the upper surface of the mold, and, in smoothing off, the trowel
should be drawn over the mold in such a manner as to exert a
moderate pressure on the excess material. The mold should
be turned over and the operation repeated.

41. A check upon the uniformity of the mixing and molding
is afforded by weighing the briquettes just prior to immersion,
or upon removal from the moist closet. Briquettes which vary
in weight more than 3 per cent, from the average should not
be tested.

Storage of the Test Pieces. 42. During the first 24 hours
after molding, the test pieces should be kept in moist air to
prevent them from drying out.

43. A moist closet or chamber is so easily devised that the
use of the damp cloth should be abandoned if possible. Cover-
ing the test pieces with a damp cloth is objectionable, as com-
monly used, because the cloth may dry out unequally, and in
consequence the test pieces are not all maintained under the
same condition. Where a moist closet is not available, a cloth
may be used and kept uniformly wet by immersing the ends in
water. It should be kept from direct contact with the test

TESTING OF CEMENT. 51

pieces by means of a wire screen or some similar arrangement.

44. A moist closet consists of a soapstone or slate box, or a
metal-lined wooden box the metal lining being covered with
felt and this felt kept wet. The bottom of the box is so con-
structed as to hold water, and the sides are provided with cleats
for holding glass shelves on which to place the briquettes.
Care should be taken to keep the air in the closet uniformly
moist.

45. After 24 hours in moist air, the test pieces for longer
periods of time should be immersed in water maintained as
near 21 degrees C. (70 degrees F.) as practicable; they may
be stored in tanks or pans, which should be of non-corrodible
material.

Tensile Strength. 46. The test may be made on any stand-
ard machine. A solid metal clip is recommended. This clip
is to be used without cushioning at the points of contact with
the test specimen. The bearing at each point of contact should
be a quarter of an inch wide, and the distance between the
centers of contact on the same clip should be one and a quarter
inches.

17. Test pieces should be broken as soon as they are re-
moved from the water. Care should be observed in centering
the briquettes in the testing machine, as cross-strains, pro-
duced by improper centering, tend to lower the breaking
strength. The load should not be applied too suddenly, as it
may produce vibration, the shock from which often breaks the
briquette before the ultimate strength is reached. Care must
be taken that the clips and the sides of the briquettte be clean
and free from grains of sand or dirt which would prevent a good
bearing. The load should be applied at the rate of 600 pounds
per minute. The average of the briquettes of each sample
tested should be taken as the test, excluding any results which
are manifestly faulty.

Constancy of Volume. 48. Methods. Tests for constancy of
volume are divided into two classes: (1) normal tests, or those
made in either air or water maintained at about 21 degrees C.
(70 degrees F.), and (2) accelerated tests, or those made in
air, steam or water at a temperature of 45 degrees C. (115 de-
grees F.) and upward. The test pieces should be allowed to
remain 24 hours in moist air before immersion in water or
steam, or preservation in air.

49. For these tests, pats about 7 l / 2 cm. (2.95 ins.) in diame-
ter, V/ 2 cm. (0.49 in.) thick at the center, and tapering to a
thin edge, should be made, upon a clean glass plate [about
10 cm. (3.94 ins.) square], from cement paste of normal con-
sistency.

52 HANDBOOK FOR CEMENT USERS.

50. Normal Test. A pat is immersed in water maintained
as near 21 degrees C. (70 degrees F.) as possible for 28 days,
and observed at intervals. A similar pat is maintained in air
at ordinary temperature and observed at intervals.

51. Accelerated Test. A pat is exposed in any convenient
way in an atmosphere of steam, above boiling water, in a
loosely closed vessel.

52. To pass these tests satisfactorily, the pats should remain
firm and hard, and show no signs of cracking, distortion or
disintegration.

53. Should the pat leave the plate, distortion may be de-
tected best with a straight-edge applied to the surface which
was in contact with the plate.

ADDITIONAL REMARKS OF THE COMMITTEE OF THE AMERICAN
SOCIETY OF CIVIL ENGINEERS.

On several matters which have been considered this Commit-
tee has not reached final conclusions, but feels that it should
make a report of progress, that the Society may be informed of
the results of its investigations and conclusions..

Selection of Sample. The selection of the sample for testing
is a detail that must be left to the discretion of the engineer;
the number and the quantity to be taken from each package
will depend largely on the importance of the work, the number
of tests to be made and the facilities for making them.

Significance of Chemical Analysis. Chemical analysis may
render valuable service in the detection of adulteration of ce-
ment with considerable amounts of inert material, such as slag
or ground limestone. It is of use, also, in determining whether
certain constituents, believed to be harmful when in excess of
u certain percentage, as magnesia and sulphuric anhydride, are
present in inadmissible proportions. While not recommending
a definite limit for these impurities, the Committee would sug-
gest that the most recent and reliable evidence appears to indi-
cate that magnesia to the amount of 5 per cent, and sulphuric
anhydride to the amount of 1.75 per cent, may safely be con-
sidered harmless.

The determination of the principal constituents of cement,
silica, alumina, iron oxide and lime, is not conclusive as an in-
dication of quality. Faulty character of cement results more
frequently from imperfect preparation of the raw material, or
defective burning, than from incorrect proportions of the con-
stituents. Cement made from very finely ground material and
thoroughly burned, may contain much more lime than the
amount usually present and still be perfectly sound. On the
other hand, cements low in lime may, on acount of careless

TESTING OF CEMENT. 53

preparation of the raw material, be of dangerous character.
Further, the ash of the fuel used in burning may so greatly
modify the composition of the product as largely to destroy the
significance of the results of analysis.

Significance of the Specific Gravity Test. The specific gra-
vity of cement is lowered by underburning, adulteration and
hydration, but the adulteration must be in considerable quan-
tity to affect the results appreciably. Inasmuch as the differ-
ences in specific gravity are usually very small, great care must
be exercised in making this determination.

Significance of the Fineness Test. It is generally accepted
that the coarser particles in cement are practically inert, and it
is only the extremely fine powder that possesses adhesive or
cementing qualities. The more finely cement is pulverized, all
other conditions being the same, the more sand it will carry and
produce a mortar of a given strength. The degree of final pul-
verization which the cement receives at the place of manufac-
ture is ascertained by measuring the residue retained on cer-
tain sieves. Those known as the No. 100 and No. 200 sieves
are recommended for this purpose.

Significance of the Normal Consistency Test. The use of a
proper percentage of water in making the pastes from which
pats, tests of setting and briquettes are made, is exceedingly
important, and affects vitally the results obtained. The de-
termination consists in measuring the amount of water re-
quired to reduce the cement to a given state of plasticity, or
to what i usually designated the normal consistency. Various
methods have been proposed for making this determination,
none of which has been found entirely satisfactory, but the
Committee recommends the one given above. The trial pastes
are made with varying percentages of water until the correct
consistency is obtained. The Committee has recommended as
normal, a paste, the consistency of which is rather wet, be-
cause it believes that variations in the amount of compression
to which the briquette is subjected in molding are likely to be
loss with such a paste. Having determined in this manner the
proper percentage of water required to produce a neat paste
of normal consistency, the proper percentage required for the
sand mortars is obtained from an empirical formula. The
Committee hopes to devise such a formula. The subject proves
to be a very difficult one, and although the Committee -has
given it much study, it is not yet prepared to make a definite
recommendation.

Significance of Test of Time of Setting. The object of this
test is to determine the time which elapses from the moment
water is added until the paste ceases to be fluid and plastic

54 HANDBOOK FOR CEMENT USERS.

(called the initial set), and also the time required for it to ac-
quire a certain degree of hardness (called the final or hard
set) . The former of these is the more important, since, with
the commencement of setting, the process of crystallization or
hardening is said to begin. As a disturbance of this process
may produce a loss of strength, it is desirable to complete the
operation of mixing and molding or incorporating the mortar
into the work before the cement begins to set. It is usual to
measure arbitrarily the beginning and end of the setting by the
penetration of weighted wires of given diameters.

Standard Sand. The Committee recognizes the grave objec-
tions to the standard quartz now generally used, especially on
account of its high percentage of voids, the difficulty of com- ,
pacting in the molds, and its lack of uniformity; it has spent
much time in investigating the various natural sands which ap-
peared to be available and suitable for use..

Mixing and Molding Machines. The Committee, after inves-
tigation of the various mechanical mixing machines, has de-
cided not to recommend any machine that has thus far been
devised, for the following reasons: (1) the tendency of most
cement to ball up in the machine, thereby preventing the work-
ing of it into a homogeneous paste; (2) there are no means of
ascertaining when the mixing is complete without stopping
the machine; and (3) the difficulty of keeping the machine
clean.

The Committee has been unable to secure satisfactory results
with the present molding machines; the operation of -machine
molding is very slow, and the present types permit of molding
but one briquette at a time, and are not practicable with the
pastes or mortars recommended.

Significance of Test of Consistency of Volume. The object is
to develop those qualities which tend to destroy the strength
and durability of a cement. As it is highly essential to deter-
mine such qualities at once, tests of this character are for the
most part made in a very short time, and are known, therefore,
as accelerated tests. Failure is revealed by cracking, checking,
swelling or disintegration, or all of these phenomena. A ce-
ment which remains perfectly sound is said to be of constant
volume.

METHODS OF CHEMICAL ANALYSIS OP THE SOCIETY FOR CHEMICAL

INDUSTRY.

Method suggested for the chemical analysis of limestones,
raw mixtures and Portland cements by the Committee on Uni-
formity in Technical Analysis, with the advice of W. F. Hil-
lebrand.

TESTING OF CEMENT. 55

Solution. One-half gram of the finely powdered substance
is to be weighed out and, if a limestone or unburned mixture,
strongly ignited in a covered platinum crucible over a strong
blast for 15 minutes, or longer if the blast is not powerful
enough to effect complete conversion to a cement in this time.
It is then transferred to an evaporating dish, preferably of
platinum for the sake of celerity in evaporation, moistened
with enough water to prevent lumping, and 5 to 10 c. c. of
strong HC1 added and digested, with the aid of gentle heat
and agitation, until solution is completed. Solution may be
aided by light pressure with the flattened end of a glass rod.*
The solution is then evaporated to dryness, as far as this
may be possible on the bath.

Silica. The residue, without further heating, is treated ar
first with 5 to 10 c. c. of strong HCI, which is then diluted to
half strength or less, or upon the residue may be poured at once
a larger volume of acid of half strength. The dish is then cov-
ered and digestion allowed to go on for 10 minutes on the
bath, after which the solution is filtered and. the separated
silica washed throughly with water. The filtrate is again
evaporated to drfness, the residue, without further heating,
taken up with acid and water and the small amount of silica
it contains separated on another filter paper. The papers con-
taining the residue are transferred wet to a weighed platinum
crucible, dried, ignited, first over a Bunsen burner until the
carbon of the filter is completely consumed, and finally over
the blast for 15 minutes and checked by a further blasting for
10 minutes or to constant weight. The silica, if great accuracy
is desired, is treated in the crucible with about 10 c. c. of HF1
and four drops of H 2 SO 4 and evaporated over a low flame to
complete dryness. The small residue is finally blasted for a
minute or two, cooled and weighed. The difference between
this weight and the weight previously obtained gives the
amount of silica.**

Alumina and Iron. The filtrate, about 250 c. c., from the
second evaporation for SiO 2 , is made alkaline with NH 4 OH
after adding HCI, if need be, to insure a total of 10 to 15 c.c.
strong acid, and boiled to expel excess of NH 3 , or until there
is but a faint odor of it, and the precipitated iron and alumi-
num hydrates, after settling, are washed once by decantation
and slightly on the filter. Setting aside the filtrate, the pre-
cipitate is dissolved in hot dilute HCI, the solution passing

*If anything remains undecomposed, it should be separated, fused with a little Carbon-
ate of Soda, dissolved and added to the original solution. Of course a small amount of
non-gelatinous silica is not to be mistaken for undecomposed matter.

** For ordinary control work in the plant laboratory this correction may, perhaps, be
neglected; the double evaporation, never.

56 HANDBOOK FOR CEMENT USERS.

into the beaker in which the precipitation was made. The
aluminum and iron are then reprecipitated by NH^OH, boiled
and the second precipitate collected and washed on the same
filter used in the first instance. The filter paper, with the pre-
cipitate, is then placed in a weighed platinum crucible, the
paper burned off and the precipitate ignited and finally blasted
5 minutes, with care to prevent reduction, cooled and weighed
as A) 2 O 3 -i-Fe 2 O 3 .*

Iron. The combined iron and aluminum oxides are fused
in a platinum crucible at a very low temperature with about
3 to 4 grams of KHSO 4 , or, better, NaHSO 4 , the melt taken up
with so much dilute R 2 SO 4 that there shall be no less than 5
grams absolute acid and .enough water to effect solu-
tion on heating. The solution is then evaporated and event-
ually heated till acid fumes come off copiously. " After cooling
and redissolving in water the small amount of silica is filtered
out, weighed, and corrected by HF1 and H 2 SO ** The filtrate
is reduced by zinc, or preferably by hydrogen sulphide, boiling
out the excess of the latter afterwards whilst passing CO 2
through the flask, and titrated with permanganate.*** The
strength of the permanganate solution should not be greater
than .0040 gr. Fe 2 O 3 per c. c.

Lime. To the combined filtrate from the Al 2 O 3 -fFe 2 O 3 pre-
cipitate a few drops of NH 4 OH are added, and the solution
brought to boiling. To the boiling solution 20 c. c. of a satu-
rated solution of ammonium oxalate is added, and the boiling
continued until the precipitated CaC 2 O 4 assumes a well-de-
fined granular form. It is then allowed to stand for 20 min-
utes, or until the precipitate has settled, and then filtered and
washed. The precipitate and filter are placed wet in a plat-
inum crucible, and the paper burned off over a small flame of a
Bunsen burner. It is then ignited, redissolved in HC1, and
the solution made up to 100 c. c. with woter. Ammonia is
added in slight excess, and the liquid is boiled. If a small
amount of A1 2 O 3 separates this is filtered out, weighed, and
the amount added to that found in the first determination,
when greater accuracy is desired. The lime is then reprecipi*
tated by ammonium oxalate, allowed to stand until settled,
filtered and washed, **** weighed as oxide by ignition and

* This precipitate contains TiO 2 , P 2 O 5 , Mn 3 O 4 .

**This correction of A1 2 O 3 , Fe 2 O 2 for silica should not be made when the HP1 correction
of the main silica has been omitted, unless that silica was obtained by only one evaporation
and filtration. After two evaporations and filtrations 1 to 2 mg of SiO 2 are still to be found
with the A1 2 O 3 , Fe 2 O 3 .

** * In this way only is the influence of titanium to be avoided and a correct result ob-
tained for iron.

* * * * The volume of wash water should not be too large. Vide Hillebrand.

TESTING OF CEMENT. 57

blasting in a covered crucible to constant weight, or deter-
mined with dilute standard permanganate.*

Magnesia. The combined filtrates from the calcium precipi-
tates are acidified with HC1 and concentrated on the steam bath
to about 150 c. c v 10 c. c. of saturated solution of Na(NHJ
HPO 4 are added, and the solution boiled for several minutes.
It is then removed from the flame and cooled by placing the
beaker in ice water. After cooling, NH 4 OH is added drop by
drop with constant stirring until the crystalline ammonium-
magnesium ortho-phosphate begins to form, and then in mod-
erate excess, the stirring being continued for several minutes.
It is then set aside for several hours in a cool atmosphere and
filtered. The precipitate is redissolved in hot dilute HC1, the
solution made up to about 100 c. c., 1 c. c. of a saturated solu-
tion of Ka(NH 4 )HPO 4 added, and ammonia drop by drop,
with constant stirring until the precipitate is again formed as
described and the ammonia is in moderate excess. It is then
allowed to stand for about two hours when it is filtered on a
paper or a Gooch crucible, ignited , cooled and weighed as

Potash and Soda. For the precipitation of the alkalies, the
well-known method of Prof. J. Lawrence Smith is to be fol-
lowed, either with or without the addition of CaCO 3 with

Sulphuric Anhydride. One gram of the substance is dis-
solved in 15 c. c. of HC1, filtered and residue washed thor-
oughly.**

The solution is made up to 250 c. c. in a beaker and boiled.
To the boiling solution 10 c. c. of a saturated solution of BaCl 2
is added slowly drop by drop from a pipette and the boiling
continued until the precipitate is well formed, or digestion
on the steam bath may be substituted for the boiling. It is
then set aside over night, or for a few hours, filtered, ignited
and weighed as BaSO

Total Sulphur. One gram of the material is weighed out in
a large platinum crucible and fused with Na 2 CO 3 and a little
KNO 3 , being careful to avoid contamination from sulphur in
the gases from source of heat. This may be done by fitting the
crucible in a hole in an asbestos board. The melt is treated
in the crucible with boiling water and the liquid poured into a
tall narrow beaker and more hot water added until the mass is
disintegrated. The solution is then filtered. The filtrate con-
tained in a No. 4 beaker is to be acidulated with HC1 and made

* The accuracy of this method admits of criticism, but its convenience and rapidity
demand its insertion.

* * Evaporation to dryness is unnecessary, unless gelatinous silica should have separated
and should never be performed on a bath heated by gas. Vide Hillebrand.

58 HANDBOOK FOR CEMENT USERS.

up to 250 c. c. with distilled water, boiled, the sulphur precipi-
tated as BaSO 4 and allowed to stand over night or for a few
hours.

Loss on Ignition. Half a gram of cement is to be weighed
out in a platinum crucible, placed in a hole in an asbestos
board so that about three-fifths of the crucible projects below,
and blasted 15 minutes, preferably with an inclined flame. The
loss by weight, which is checked by a second blasting of five
minutes, is the loss on ignition.

Eecent investigations have shown that large errors in results
are often due to the use of impure distilled water and reagents.
The analyst should, therefore, test his distilled water by evapo-
ration and his reagents by appropriate tests before proceeding
with his work.

METHODS OF TESTING OF THE CORPS OF ENGINEERS, U. S. ARMY.

The document, Professional Papers No. 28, Corps of Engi-
neers, U. S. A., is mainly in accord with the adopted report of
the American Society of Civil Engineers. It states the gen-
eral object of tests in the following words :

The object of tests is to establish two probabilites : First,
that the product of the given cement will develop the desired
strength and hardness soon enough to enable it to bear the
stresses designed for it; second, that it will never thereafter
fall below that strength and hardness.

With respect to fineness it emphasizes the necessity of de-
termining the proportion of very fine cement rather than the
proportion above a certain size. It therefore recommends the
No. 100 sieve for both Portland and natural cements, and fre-
quent inspection of sieves.

A test for specific gravity is recommended. The reasons for
it are stated as follows:

This test is made with simple appliances, and its result is
immediately known. It appears to connect itself quite def-
initely with the degree of calcination which the cement has
received. The higher the burning, short of vitrification, the
better the cement and the higher the specific gravity. This
test has another value, in that the adulterations of Portland
cement most likely to be practiced and most to be feared are
made with materials which reduce the specific gravity. The
test is therefore of value in determining a properly burned,
non-adulterated Portland. If underburned, the specific grav-
ity may fall below 3; it may reach 3.5 if the cement has been
overburned. No other hydraulic cement is so heavy in pro-
portion to volume, natural cement having a specific gravity

TESTING OF CEMENT. 59

of about 2.5 to 2.8 and puzzolan (slag) of about 2.7 to 2.8.
Properly burned Portland, adulterated with slag, will fall
below 3.1.

With reference to the test of activity or time of setting
some of the statements are somewhat at variance with those
of prominent manufacturers, and all engineers will not be in
strict accord with them all. They are as follows :

This test is direct in so far as its limits relate to the time
necessary to get the cement in place after mixing, which
must not be greater 'than the time of initial set, and to
the time within which the cement product must take its load,
which must not be less than the time of permanent set. It is
indirect in so far as its limits relate to the probable final
strength, elasticity, and hardness of the cement mixtures. In
the latter respect it appears to be reasonably well established
that cements exhibiting great activity give, after long
periods, results inferior to those with action less rapid.
Generally speaking, both periods of set are lengthened by in-
crease of moisture and shortened by increase of temperature.
Some manufacturers claim that their cements show their best
results when gauged with particular percentages of water.
It is not considered good policy to encourage these peculiar-
ities at the expense of the uniformity of tests which is so
greatly desired. It is better to adopt a definite proportion
of water for gauging and require all cements of the same class
to stand or fall on their showing when so gauged. Such a
percentage, adopted and known, will probably be used by
manufacturers in testing goods sold to the Engineer Depart-
ment, and a greater harmony between mill and field tests of
the same cement will result. In gauging Portland cement in
damp weather the samples should be thoroughly dried before
adding water. This precaution is not deemed necessary with
natural cement. Sufficient uniformity of temperature will
result if the testing room be comfortably warmed in winter
and the specimens be kept out of the sun in a cool room in
summer, and under a damp cloth till set.

Regarding tests of strength the board considers the 7 and
28-day tests for tensile strength the best on the whole. With
regard to variation in results it says that if the conditions
have been carefully observed and several discrepant results
are obtained, the highest may be right, but the others are cer-
tainly wrong, and that no averaging should be done. The
board classes quick setting with early attainment of high
tensile strength and considers that the relation between

60 HANDBOOK FOR CEMENT USERS.

early hydraulic intensity and the final excellence of a cement
product are equally applicable to the indications from tensile
tests. This will hardly be accepted by manufacturers as true
for every cement under all conditions, though nearly all will
agree with the board that

A cement which tests moderately high at 7 days and shows
a substantial increase to 28 days is more likely to reach the
maximum strength slowly and retain it indefinitely with a
low modulus of elasticity than a cement which tests abnor-
mally high at 7 days with little or no increase at 28 days.

The tests recommended by the board are those for fineness,
specific gravity, soundness or constancy of volume in setting,
time of setting, tensile strength, for Portland cement, the
specific-gravity and soundness tests being omitted for nat-
ural hydraulic cements. Bonuses for tests above a fixed point
are said to be likely to result in unsoundness in ways not
quickly detected.

The Engineer board goes into great detail in the matter of
manipulation of cements for tests as follows :

Fineness. Place 100 parts (denominations determined
by subdivisions of the weighing machine used) by weight on
a sieve with 100 holes to the linear inch, woven from brass
wire No. 40, Stubb's wire gauge; sift by hand or mechanical
shaker until cement ceases to pass through.

The weight .of the material passing the sieve plus the
weight of the dust lost in air, expressed in hundredths of the
original weight, will express the percentage of fineness. In
order to determine this percentage the residue on the sieve
should be weighed.

It is only the impalpable dust that possesses cementitious
value. Fineness of grinding is therefore an essential quality
in cements to be mixed with sand. The residue on a sieve
of 10 meshes to the inch is of no cementitious value, and
even the grit retained on a sieve of 40,000 openings to the
square inch is of small value. The degree of fineness pre-
scribed in these specifications (92 per cent.) for Portland
through a sieve of 10,000 meshes to the square inch is quite
commonly attained in high-grade American cements, but rarely
in imported brands.

Specific Gravity. The standard temperature for spe-
cific gravity determinations is 62 degrees F., but for cement
testing temperatures may vary between 60 degrees and 80 de-
grees F. without affecting results more than the probable error

TESTING OF CEMENT. 61

in the observation. Use any approved form of volumenometer
or specific gravity bottle, graduated to cubic centimeters with
decimal subdivisions. Fill instrument to zero of the scale with
benzine, turpentine, or some other liquid having no action upon
cements. Take 100 grams of sifted cement that has been pre-
viously dried by exposure on a metal plate for 20 minutes to a
dry heat of 212 degrees F., and allow it to pass slowly into the
fluid of the volumenometer, taking care that the powder does
not stick to the sides of the graduated tube above the fluid and
that the funnel through which it is introduced does not touch
the fluid. Read carefully the volume of the displaced fluid to
the nearest fraction of a cubic centimeter. Then the approx-
imate specific gravity will be represented by 100 divided by
the displacement in cubic centimeters. The operation re-
quires care.

Setting Quality and Soundness. The quantity of water and
the temperature of water and air affect the time of setting.
The specifications contemplate a temperature varying not more
than 10 degrees from 62 degrees F., and quantities of water
given herein : For Portland cements use 26 per cent, of water ;
for puzzolan cements use 30 per cent, of water. Mix thor-
oughly for five minutes, vigorously rubbing the mixture under
pressure; time to be estimated from moment of adding water
and to be considered of importance.

Make on glass plates two cakes from the mixture about
3 ins. in diameter, i/ 2 in. thick at middle, and drawn to thin
edges, and cover them with a damp cloth or place them in a
tight box not exposed to currents of dry air. At the end of
the time specified for initial set apply the needle 1-12 in. diam-
eter weighted to ^-Ib. to one of the cakes. If an indentation
is made the cement passes the requirement for initial setting,
if no indentation is made by the needle it is too quick setting.
At the end of the time specified for "final set" apply the
needle 1-24 in. diameter loaded to 1 Ib. The cement cake
should not be indented.

Expose the two cakes to air under damp cloth for 24 hours.
Place one of the cakes, still attached to its plate, in water for
28 days; the other cake immerse in water at about 70 degrees
temperature supported in a rack above the bottom of the re-
ceptacle; raise the water gradually to the boiling point and
maintain this temperature for six hours and then let the water
with cake immersed cool. Examine the cakes at the proper
time for evidences of expansion and distortion. Should the
boiled cake become detached from the plate by twisting and
warping or show expansion cracks the cement may be rejected,
or it may await the result of 28 days in water. If the fresh-

62 HANDBOOK FOR CEMENT USERS.

water cake shows no evidence of swelling, the cement may be
used in ordinary work in air or fresh water for lean mixtures.
If distortion or expansion cracks are shown on the fresh-
water cake, the cement should be rejected. Of two or more
cements offered, all of which will stand the fresh-water cake
tests for soundness, the cements that will stand the boiling
tests also are to be preferred.

Tensile Strength Neat Tests. Use unsifted cements.
Place the amount to be mixed on a smooth, non-absorb-
ent slab; make a crater in the middle sufficient to hold
the water; add nearly all the water at once, the remainder*
as needed; mix thoroughly by turning with the trowel, and
vigorously rub or work the cement for five minutes.

Place the mold on a glass or slate slab. Fill the mold with
consecutive layers of cement, each when rammed to be ^-in.
thick. Tap each layer 30 taps with a soft brass or copper
rammer weighing 1 Ib. and having a face %-in. diameter or
7-16-in. square with rounded corners. The tapping or ram-
ming is to be done as follows : While holding the forearm and
wrist at a constant level, raise the rammer with the thumb
and forefinger about %-in. and then let it fall freely, repeat-
ing the operation until the layer is uniformly compacted by
30 taps.

This method is intended to compact the material in a man-
ner similar to actual practice in construction, when a metal
rammer. is used weighing 30 Ibs., with a circular head 5 ins.
in diameter, falling about 8 ins. upon layers of mortar or con-
crete 3 ins. thick. The method permits comparable results to
be obtained by different observers.

After filling the mold and ramming the last layer, strike
smooth with the trowel, tap the mold lightly in a direction
parallel to the base plate to prevent adhesion to the plate,
and cover for 24 hours with a damp cloth. Then remove the
briquette from the mold and immerse in fresh water, which
should be renewed twice a week for the specified time if run-
ning water is not available for a slow current. If molds are
not available for 24 hours, remove from the molds after final
set, replacing the damp cloth over the briquettes. In remov-
ing briquettes before hard-set great care should be exercised.
Hold the mold in the left hand and, after loosening the latch,
tap gently the sides of the mold until they fall apart. Place
the briquettes face down in the water trough.

For neat tests of Portland cement use 20 per cent, of water
by weight. For neat tests of puzzolan cement use 18 per
cent, of water by weight. For neat tests of natural cement
use 30 per cent, of water by weight. Nearly all this water is

TESTING OF CEMENT.

retained by Portland cement, whereas only about one-third of
the gauging water is retained by puzzolan or natural cements ;
from this it follows that an apparent condition of plasticity or
fluidity that ultimately little injures Portland paste, very ser :
iously injures puzzolan or natural mortars and concretes by
leaving a porous texture on the evaporation of the surplus
water.

Sand Tests. The proportions 1 cement to 3 sand are to be
used in tests of puzzolan and Portland, and 1 cement to 1
sand in tests of natural or Rosendale cements. Crushed
quartz sand, sifted to pass a standard sieve with 20 meshes
per lin. in. and to be retained on a standard sieve with 30
meshes to the inch, is to be used.

After weighing carefully, mix dry the cement and sand
until the mixture is uniform, add the water as in neat mix-
tures, and mix for five minutes by triturating or rubbing to-
gether the constituents of the mortar. This may be done
under pressure with a trowel or by rubbing between the
fingers, using rubber gloves. The rubbing together seems
necessary to coat thoroughly the facets of the sand with the
cement paste.

It is found that prolonged rubbing, when not carried be-
yond the time of initial set, results in higher tests. Five min-
utes is the time of mixing quite generally adopted in Euro-
pean specifications. The briquettes are to be made as pre-
scribed for neat mixtures.

Portland cements require water from 11 to 12 per cent, by
weight of constituent sand and cement for maximum strength
in tested briquettes ; puzzolan, about 9 to 10 per cent., and na-
tural, about 15 to 17 per cent. Mixtures that at first appear
too dry for testing purposes often become more plastic under
the prolonged working required herein.

In general, about four briquettes constitute the maximum
number that may be made well within the time required for
initial setting of moderately slow-setting cements. Three
such batches of sand mixtures should be made, and one
briquette of each batch may be broken at 7 and 28 days, giv-
ing three tests at each period. At least one batch of neat
cement briquettes should be made.

If the first briquette broken at each date fulfills the min-
imum requirements of these specifications, it is not neces-
sary to break others, which may be reserved for long-time
tests. If the first briquette does not pass the test for tensile
strength, then briquettes may be broken at seven days, and the
remaining six reserved for 28-day tests. The highest result
from any sample is to be taken as the strength of the sample

64 HANDBOOK FOR CEMENT USERS.

when the break is at the least section of briquette.

If, on the 28-day tests, the cement not only more than ful-
fills the minimum requirements of these specifications, but
also shows unusual gain in strength, it may still be accepted
if the other tests are satisfactory, notwithstanding a low
seven-day test, if early strength is not a matter of importance.
Such cements are likely to be permanent.

For a batch of four briquettes, the following quantities are
suggested as in accord with these specifications. Water is
measured by fluid-ounce volumes, not by weight, temperature
varying not more than 10 degrees from 62 degrees F.

Portland Cement. Neat: 20 ozs. of cement, 4 ozs. of water.
Mix wet five minutes.

Sand : 15 ozs. sand, 5 ozs. cement, 2% ozs. water. Mix thor-
oughly dry ; then mix wet five minutes.

Puzzolan Cement. Neat: 20 ozs. cement, 3% ozs. water.
Mix wet five minutes.

Sand: 15 ozs. sand, 5 ozs. cement, 2 ozs. water. Mix thor-
oughly dry; then mix wet five minutes.

Natural Cement. Neat: 20 ozs. cement, 6 ozs. water. Mix
thoroughly dry; then mix wet five minutes.

Sand : 10 ozs. cement, 10 ozs. sand, 3% ozs. water. Mix dry ;
then wet for five minutes.

For measuring tensile strength, a machine that applies the
stress automatically at a uniform rate is preferable to one con-
trolled entirely by hand. These specifications for tensile
strength contemplate the application of stress at the rate of
400 Ibs. per minute to briquettes made as prescribed herein.
A rate so rapid as to approximate a blow or so slow to approx-
imate a continued stress will give very different results.

The tests for tensile strength are to be made immediately
after taking from the water or while the briquettes are still
wet. The temperature of the water during immersion should
be maintained as nearly constant as practicable; not less than
50 degrees nor more than 70 degrees F.

The tests are to be made upon briquettes 1 in. sq. at place of
rupture. The specifications contemplate the use of the form of
briquette recommended by the committee of the American So-
ciety of Civil Engineers, held when tested by close-fitting metal
clips, without rubber or other yielding contacts. The breaks
considered in the tests are to be those occurring at the smallest
section, 1 in. sq.

Simple Tests. Tests of cement received upon a work in
progress must often be of much simpler character than pre-
scribed herein. Tests on the work are mainly to ascertain
whether the article supplied is genuine cement, of a brand pre-

TESTING OF CEMENT.

viously tested and accepted, and whether it is a reasonably
sound and active cement that will set hard in the desired time,
and give a good, hard mortar. Simple tests may give this in-
formation, and such should be multiplied Avhether or not more
elaborate tests be made. Pats and balls of cement and mortar
from the storehouse and mixing platform or machine should
be frequently made. The setting or hardening qualities, as de-
termined roughly by estimating time and by pressure of the
thumbnail, should be observed; the hardness of the set and
strength, by cracking the hardened pats or cakes between the
fingers, and by dropping the balls from the height of the arm
upon a pavement or stone and observing the result of the
impact.

By placing the pats in water as soon as hardened sufficiently
and raising the temperature to the boiling point for a few
hours and observing the character and color of the fracture
after sufficient immersion, information as to the character of
the material, whether hydraulic, a Portland or puzzolan,
whether too fresh or possibly "blowy," may be speedily and
quite well ascertained without measuring instruments.

Many engineers and users of cements regard such simple
tests, taken in connection with the weight and fineness of the
cement and the apparent texture and hardness of the mortars
and concretes in the work, sufficient field tests of a material
of known repute. The more elaborate tests, described above,
should be made in well-equipped laboratories by skilled cement
testers.

Classification of Tests. The tests to be made are of two
classes: (1) Purchase tests on samples furnished by bidders
to ascertain whether the bidder may be held on the sample to
the delivery of suitable material, should his offer be accepted.
(2) Acceptance tests on samples taken at random from deliv-
eries, to ascertain whether the material supplied accords with
the purchase sample, or is suitable for the purpose of the work,
as stated in the specifications for cement supplies.

(1) Purchase Tests. Under these specifications' bids for
Portland cements will be restricted to brands that have been
approved after at least three years' exposure in successful use
under similar conditions to those of the proposed work. This
specification limits proposals to manufacturers of cements of
established repute, and in so far lessens the dependence to be
placed upon tests of single samples of cement in determining
the probable quality of the cements offered, that sample pack-
ages may not be required with the proposals when the brand is
known to the purchaser. When the cement is not known to
the purchasing officer by previous use, a barrel of it should be

66 HANDBOOK FOR CEMENT USERS.

required as representing the quality of cement to be supplied.
A full set of tests should be made from this sample, and sub-
sequent deliveries be required to show quality at least equal to
the sample.

In this connection it is advisable in districts where well-
equipped laboratories have been established, that sample pack-
ages of the cements in use in that territory, as sold in the open
market, be obtained and tested as occasion offers, to ascertain
the characteristic qualities of the brands as commercial arti-
cles, the information to be used in subsequent purchases of
cements.

When purchase samples are waived, acceptance tests should
be based upon the known qualities of the brand, as shown by
previous tests. The sample barrel should not be broken further
than to take therefrom the necessary samples for testing. Aft-
erwards it should be put away in a dry place and kept for fur-
ther testing, should the results obtained be disputed.

(2) Acceptance Tests. The tests to be made on cements de-
livered under contract depend not only on the extent, charac-
ter, and importance of the work itself, but also on the time
available between the delivery and the actual use of the ma-
terial.

(a) On very important and extensive works, equipped with
a testing laboratory and adequate storehouses, where cement
may be kept at least 30 days before being required for use, full
and elaborate tests should be made, keeping in view the fact
that careful tests of few samples are more valuable than hur-
ried tests of many samples.

(b) On active works of ordinary character, when time will
not permit full tests, and on small works where the expenses
of a laboratory are not justified, the tests must necessarily be
limited to such reasonable precautions against the acceptance
and use of unfit material as may be taken in the usually short
interval between the receipt and use of the material.

Such conditions were in view in formulating the specifica-
tion that proposals will be received from manufacturers of such
cements only as have been proved by at least three years' use
under similar conditions of exposure. Of the tests named in
the specifications those for fineness, activity or hydraulicity,
specific gravity, weight of packages, and accelerated tests for
indications as to soundness, may be made within two days after
the receipt of the material and with a very small outlay for in-
struments."

Cement of established repute, shown by specific gravity and
fineness to be properly burnt and ground, or normal for the
brand, that will set hard in reasonable time, the cakes snap-

TESTING OF CEMENT. 67

ping with a clean fracture when broken between the fingers,
and standing the tests above named, may be accepted and used
with reasonable certainty of success. Nevertheless, packages
taken at random from the deliveries should occasionally be set
aside and samples taken therefrom sent to a testing laboratory
for the more elaborate tests for tensile strength (and for
soundness should the boiling tests not be conclusive). The
final acceptance and payment for such cement as may not
have been actually placed in the work should, by agreement, be
made to depend upon such tests.

In all cases where cement has been long stored it should be
carefully tested before use to ascertain whether it has deterior-
ated in strength.

Should the simple tests give unsatisfactory or suspicious re-
sults, then a full series of tests should be carefully made.

When Portland cement is in question the specific gravity and
fineness should be made to guard against adulteration, and in
all cases test weighings should be made to guard against short
weights.

In cases where the amount of cement or the importance of
the work will not justify the purchase of the simple-apparatus
required for the specific gravity, fineness, and boiling tests, the
cement can be accepted on the informal tests mentioned here-
in, which require no apparatus whatever, but in such cases
cements well known to the purchaser by previous use should
be selected, and purchased directly from the manufacturer or
his selling agent in order that responsibility for the cement
may be fixed.

Certified tests by professional inspectors, made as prescribed
herein on samples taken from the cement to be shipped to the
work, in a manner analogous to that customary among engi-
neers in the purchase of structural steel and iron, may be re-
quired in such cases.

Sampling. The entire package from parts of which tests are
to be made is to be regarded as the sample tested. It should
be marked with a distinctive mark that must also be applied
to any part tested. The package should be set aside and pro-
tected against deterioration until all results from tests made
from it are reached and accepted by both parties to the con-
tract for supplies.

Cement drawn from several sample packages should not be
mixed or mingled, but the individuality of each sample pack-
age should be preserved.

In testing it should be borne in mind that a few tests from
any sample, carefully made, are more valuable than many
made with less care.

68 HANDBOOK FOR CEMENT USERS.

The amount of material to be taken for formal tests is indi-
cated herein where weights of the constituents of four
briquettes are given, to which should be added the amount
necessary for the tests for specific gravity, activity, and
soundness.

In extended tests the material should be taken from the
sample package from the heads and center of barrel, and from
the ends and center of bag, by such an instrument as is used
by inspectors of flour. All material taken from the same sam-
ple package may be thoroughly mixed or mingled and the tests
be made therefrom as showing the true character of the con-
tents of the sample package.

In making formal tests at the work for acceptance of cement,
sample packages should be taken at random from among sound
packages. The number taken must depend upon the importance
and character of the work, the available time, and the capacity
of the permanent laboratory force. For tensile strength the
tests with sand are considered the more important and should
always be made. Tests neat should be made if time permits.

It is. not necessary in any case on a large work to test more
than 10 per cent, of the deliveries, even of doubtful cement, and
a much less number of samples may be taken should no cause
for distrust be revealed by the tests made. In very important
work of small extent each package may be tested. A cement
should be rejected if the samples show dangerous variation in
quality or lack of care in manufacture and resulting lack of
uniformity in the product without regard to the proportion of
failures among samples tested.

In all cases in the use of cements the informal or simple tests
of the character named herein should be constantly carried on.
These constitute most valuable tests. Whenever any faulty
material is indicated by such tests, elaborate tests should be at
once instituted and should the fault be confirmed, the cement
delivered and not used should be rejected and the use of the
brand be discontinued.

Tests for Weight. From time to time packages should be
weighed in gross and afterwards the weight of neat cement and
tare of the packages determined. If short weight of neat
cement is indicated, a sufficient number of packages should be
weighed and the average net weight per package ascertained
with sufficient certainty to afford a satisfactory basis of set-
tlement.

Records. For tests by professional laboratories no general
requirements as to records seem to be necessary. Each labora-
tory has its own blanks with certificate, and if a copy of the
specifications be sent with the samples, the record returned

TESTING OF CEMENT,

should be sufficient. For records of formal tests on the work,
or in a district laboratory, blank forms should be used. It is
desirable to have the specification requirements stated on the
form. Notations should be adopted to show for each test that
the cement passed or failed or that the test was not made. No
inference should be drawn from the lack of any entry other
than that the recorder has neglected his duty.

Silica Cement or Sand Cement. This is a patented article
manufactured by grinding together silica or clean sand with
Portland cement, by which process the original material is
made extremely fine and its capacity to cover surfaces of con-
crete aggregates is much increased. The sand is an adultera-
tion, but on account of the extreme fineness of the product it
serves to make mortar or concrete containing a given propor-
tion of pure cement much more dense, the fine material being
increased in volume.

The increase in cementing capacity due to the fine grinding
of the cement constituent offsets, in great degree, the effects of
the sand adulteration, so that sand cement made from equal
weights of cement and sand approximates in tensile strength
to the neat cement and the material is sold as cement.

The extreme fine grinding also improves cement that contains
expansives, but nevertheless sand cement should not be pur-
chased in the market, but should be made on the work from
approved materials, if used for other purposes than for grout-
ing, for which it is peculiarly adapted.

Whether this material should be used in important works for
mortar and concrete, the board considers a question of cost and
expediency.

Over against the saving in cement may be placed the royalty
on a patented article, the cost of the plant and of manufacture,
the inconvenience of attaching a manufacturing establishment
to a work under construction, and other elements bearing not
only on first cost of cementing material but also involving the
element of time. When cement is high priced, means of trans-
portation limited, labor, sand, and concrete materials cheap
and abundant, the conditions may justify the use of sand
cement on economic grounds. In any case, the cement from
which the product is made should be tested precisely as other
cements.

Slag Cement. This term is applied to cement made by inti-
mately mixing by grinding together granulated blast-furnace
slag of a certain quality and slaked lime, without calcination
subsequent to the mixing. This is the only cement of the puz-
zolan class to be found in our markets (often branded as Port-
land), and as true Portland cement is now made having slag

70 HANDBOOK FOR CEMENT USERS.

for its hydraulic base, the term a slag cement" should be
dropped and the generic term puzzolan be used in advertise-
ments and specifications for such cements.

Puzzolan cement made from slag is characterized physically
by its light lilac color ; the absence of grit attending fine grind-
ing and the extreme subdivision of its slaked lime element ; its
low specific gravity (2.6 to 2.8) compared with Portland (3 to
3.5) ; and by the intense bluish green color in the fresh fracture
after long submersion in water, due to the presence of sul-
phides, which color fades after exposure to dry air.

The oxidation of sulphides in dry air is destructive of puz-
zolan cement mortars and concretes so exposed. Puzzolan is
usually very finely ground, and when not treated with soda
sets more slowly than Portland. It stands storage well, but
cements treated with soda to quicken setting become again
very slow setting from the carbonization of the soda (as well
as the lime) after long storage.

Puzzolan cement properly made contains no free or anhy-
drous lime, does not warp or swell, but is liable to fail from
cracking and shrinking (at the surface only) in dry air.

Mortars and concretes made from puzzolan approximate in
tensile strength similar mixtures of Portland cement, but their
resistance to crushing is less, the ratio of crushing to tensile
strength being about 6 or 7 to 1 for puzzolan and 9 to 11 to 1
for Portland. On account of its extreme fine grinding puzzo-
lan often gives nearly as great strength in 3 to 1 mixtures as
neat.

Puzzolan permanently assimilates but little water compared
with Portland, its lime being already hydrated. It should be
used in comparatively dry mixtures well rammed, but while re-
quring little water for chemical reactions, it requires for per-
manency in the air constant or continuous moisture.

Proper Uses of Puzzolan Cement. Puzzolan cement never
becomes extremely hard like Portland, but puzzolan mortars
and concrete are tougher or less brittle than Portland. The
cement is well adapted for use in sea water, and generally in
all positions where constantly exposed to moisture, such as
in foundations of buildings, sewers and drains, and under-
ground works generally, and in the interior of heavy masses
of masonry or concrete. It is unfit for use when subjected to
mechanical wear, attrition, or blows. It should never be used
where it may be exposed for long periods to dry air, even after
it has well set. It will turn white and disintegrate, due to
the oxidation of its sulphides at the surface under such ex-
posure.

TESTING OF CEMENT. 71

OTHER TESTS.

The following points are not touched in the foregoing re-
ports :

Microscopical Tests. These are generally considered to be
unnecessary, but they are of some value in determining adul-
terants and the character of the grains of cement, thus giving
some check on burning and grinding. From a hand-microscope
to magnifying powers of 80 to 600 diameters are recommended
by various engineers.

Compressive Strength. The foregoing report dismisses tests
of compressive strength as unnecessary, "the ratio of com-
pressive to tensile strength of the same class of cements being
quite uniform" and the tensile test being much more easily
made. The most prominent German manipulators of cement
do not report this uniformity, and in recent discussions before
technical societies are reported to consider compressive tests
more important than tensile tests, though recommending that
both be made. Some American engineers recommend them,
a few depending upon them to the exclusion of those of tensile
and transverse strength. The opinion seems to be general that
the tests can not be made in a temporary laboratory, must be
made in permanent commercial or college laboratories having
the necessary machines and experience. Too few have used
the method to have any fixed idea as to form and dimensions
of test pieces. All would treat the mortar the same as for
tension tests. There are several methods of getting a true
bearing in the press, truing with trowel, setting against glass
and the use of sheets of lead, thick paper or cardboard, plaster
of paris, or fine sand. All the prominent machines are men-
tioned, and the rate of applying the stress varies up to 1,000
pounds a minute.

Adulterations. Microscopic examination may detect adul-
teration. Slag adulterant may be detected by stirring the
cement into a mixture of methylene iodide and benzine. When
allowed to stand the cement will settle to the bottom, with the
slag on top. The density of the mixture must be carefully
fixed at the desired amount, say 2.95, by adding the proper
amount of benzine. Machines are made for tests of abrasion
of cement and concrete. A number of other tests are proposed

72 HANDBOOK FOR CEMENT USERS.

for special purposes, but they need not be considered here, as
the tests given are those which are of most value for commer-
cial purposes, and those not mentioned are of little value unless
made and interpreted by experts.

In a paper by Prof. W. K. Hatt before the Indiana Engineer-
ing Society occurs the following paragraph, indicating a method
of detecting slag adulteration of cement :

The appearance of the slag cement is characterized by a del-
icate lilac color, in some cases almost white. When cement js
made from slag by a process involving roasting, the cement is
of a dark color like that of ordinary dark colored Portland. It
has not the coarse or gritty feeling which characterizes most
Portland cement. It works fat, sets slowly and passes ordinary
tests of permanence of volume.

A pat of the cement exposed to the air has to be well covered
to prevent the surface from cracking. After drying out, it will
exhibit discolorations, yellowish or brown, whereas the pat
hardened under water will not exhibit such discolorations.
The characteristic color of the fracture of a water-hardened
briquette is green, but when the briquette dries out the frac-
ture becomes white. The writer has noticed this green color
with a subsequent change to white in the case of a well known
Portland cement, and also the discolorations in the pat, indi-
cating slag adulteration. The green color is due to the pres-
ence in slag cement of sulphide of iron or sulphide of calcium.
This sulphide becomes oxidized on exposure to the air and
changes color. Slag cements usually contain from 1 to 1% per
cent, of sulphides. It is this tendency to oxidization on ex-
posure to air which is destructive to mortar made of slag
cements containing an excess of sulphides and makes it neces-
sary to use the product in underground situations or the in-
terior of thick walls. A parallel test of briquettes hardened in
air and water should be made to check up presence of sulphides.
This disintegration does not occur in case of all slag cements.
It is not a necessary defect.

Accelerated Tests. Other accelerated tests than those
given above will be found in forms of specification in the fol-
lowing chapter. In the methods proposed by Prof. Tetmajer,
the pats are put in cold water as soon as possible after gaug-
ing, the water is raised in about one hour to boiling tempera-
ture and the boiling is continued for three hours. Some slow-
setting cements can not be put into the water until they have
set. The pats should not have thin edges but should be rolled

TESTING OF CEMENT. 73

into balls and carefully flattened. Le Chatelier makes the pats
in cylindrical form, 3 centimeters long and the same diameter.
An American would make the dimensions each one inch.
Needles are set in each end and observations on the distance
apart of their points show the amount of swelling. The water
is raised to boiling point in fifteen to thirty minutes and main-
tained there for six hours. The pats are allowed to cool before
measurements are taken. The pats are allowed to set and the
test is made within twenty-four hours after the time of final
set. Other accelerated tests use moist hot air, steam 'and hot
water, steam or water under pressure, dry closets under a tem-
perature above boiling point, and a gas flame. The steam and
hot water tests are most uniform and satisfactory and the boil-
ing test is much the easiest of application.

Bending, adhesion, abrasion, resistance to freezing and re-
sistance to action of sea water are all advised by a few experts,
but there are no settled opinions as to their general value and
the methods of making them.

SPECIFICATIONS FOR CEMENT.

The general principles upon which specifications for the ac-
ceptance or rejection of cement should be prepared may well
be stated, and the practical application of these principles ex-
emplified by selections from various specifications in use in
various parts of the country. The great variations in speci-
fications for cement for the same uses would seem to be due
largely to the failure to recognize such principles, though,
when stated, they seem to be axiomatic.

The cement should be suited to the work in which it is to
be used. This will decide whether natural hydraulic, puzzo-
lan, or Portland cement shall be used and the grade of the lat-
ter. Economy should be one of the elements considered and
may turn the decision to a natural cement in one locality while
some grade of Portland cement would be used in another. The
decision regarding the cement to be used affects the specifica-
tions for mortar and concrete also.

The exposure of the work to the weather or its protection
from external conditions by position in the interior of piers
or foundations or in rock or deep excavations under constant
conditions of temperature, moisture, etc., will be prominent
in deciding what specifications to adopt for the cement to be
used.

For external work the conditions of variation in tempera-
ture, drainage, possibility of shocks, blows and abrasions, ap-
pearance, determine the grade of Portland cement to be used.
Here, too, the specifications for mortar and concrete are closely
connected with the specifications for cement.

In cases of joint action of concrete with other materials,
as in reinforced concrete, fireproofing or other combination
structures, other qualities than the tensile or compressive
strength may make the decision.

Cement for mortar for laying stone must often be selected
for its non-staining qualities.

The rate of setting is freqquently a prime factor in making
the decision, especially in sidewalk, curb and facing work,
and in structures under water.

SPECIFICATIONS FOR CEMENT. 75

STANDARD SPECIFICATIONS FOR CEMENT, ADOPTED BY THE AMERICAN
SOCIETY FOR TESTING MATERIALS.

1. General Conditions. All cement shall be inspected.

2. Cement may be inspected either at the place of manufac-
ture or on the work.

3. In order to allow ample time for inspecting and testing,
the cement should be stored in a suitable weather-tight building
having the floor properly blocked or raised from the ground.

4. The cement shall be stored in such a manner as to permit
easy access for proper inspection and identification of each
shipment.

5. Every facility shall be provided by the contractor and a
period of at least twelve days allowed for the inspection and
necessary tests.

6. Cement shall be delivered in suitable packages with the
brand and name of manufacturer plainly marked thereon.

7. A bag of cement shall contain 94 pounds of cement net.
Each barrel of Portland cement shall contain 4 bags, and each
barrel of natural cement shall contain 3 bags of the above net
weight.

8. Cement failing to meet the seven-day requirements may
be held awaiting the results of the twenty-eight day tests be-
fore rejection.

9. All tests shall be made in accordance with the methods
proposed by the Committee on Uniform Tests of Cement of the
American Society of Civil Engineers, presented to the Society
January 21, 1903, and amended January 20, 1904, with all sub-
sequent amendments thereto. (See addendum to these spe-
cifications.)

10. The acceptance or rejection shall be based on the follow-
ing requirements :

11. NATURAL CEMENT. Definition. This term shall be ap-
plied to the finely pulverized product resulting from the calci-
tion of an argillaceous limestone at a temperature only suffi-
cient to drive off the carbonic acid gas.

12. Specific Gravity. The specific gravity of the cement
thoroughly dried at 100 degrees C., shall be not less than 2.8.

13. Fineness. It shall leave by weight a residue of not
more than 10 per cent, on the No. 100, and 30 per cent, on the
No. 200 sieve.

14. Time of Setting. It shall develop initial set in not less
than ten minutes, and hard set in not less than thirty minutes,
nor more than three hours.

15. Tensile Strength. The minimum requirements for ten-
sile strength for briquettes one inch square in cross section

76 HANDBOOK FOR CEMENT USERS.

shall be within the following limits, and shall show no retro-
gression in strength within the periods specified :*

Age. Neat Cement. Strength.

24 hours in moist air 50-100 Ibs.

7 days (1 day in moist air, 6 days in water) 100-200 Ibs.

28 days(l day in moist air, 27 days in water) 200-300 Ibs.

One Part Cement, Three Parts Standard Sand.

7 daysfl day in moist air, days in water) 25-75 Ibs.

28 days(l day in moist air, 27 days in water) 75-150 Ibs.

16. Constancy of Volume. Pats of -neat cement about three
inches in diameter, one-half inch thick at centre, tapering to
a thin edge, shall be kept in moist air for a period of twenty-
four hours.

(a) A pat is then kept in air at normal temperature.
(~b) Another is kept in water maintained as near 70 de-
grees F. as practicable.

1.7. These pats are observed at intervals for at least 28
days, and, to satisfactorily pass the tests, should remain firm
and hard and show no signs of distortion, checking, cracking
or disintegrating.

18. PORTLAND CEMENT. Definition. This term is applied to
the finely pulverized product resulting from the calcination to
incipient fusion of an intimate mixture of properly propor-
tioned argillaceous and calcareous materials, and to which no
addition greater than 3 per cent, has been made subsequent to
calcination.

19. Specific Gravity. The specific gravity of the cement,
thoroughly dried at 100 degrees C., shall be not less than 3.10.

20. Fineness. It shall leave by weight a residue of not more
than 8 per cent, on the No. 100, and not more than 25 per cent,
on the No. 200 sieve.

21. Time of Setting. It shall develop initial set in not less
than thirty minutes, but must develop hard set in not less
than one hour, nor more than ten hours.

22. Tensile Strength. The minimum requirements for ten-
sile strength for briquettes one square inch in section shall be
within the following limits, and shall show no retrogression
in strength within the periods specified.**

Age. Neat Cement. Strength.

24 hours in moist air 150-200 Ibs.

7 days(l day in moist air, 6 days in water) 450-550 Ibs,

28 days(l day in moist air, 27 days in water) 550-650 Ibs.

* For Example The minimum requirement for the 24 hour neat cement test should
be some value within the limits of 50 and 100 pounds, and so on for each period stated.

**For Example The minimum requirement for the 24 hour neat cement test should
be some value within the limits of 160 and 200 pounds, and so on for each period stated.

SPECIFICATIONS FOR CEMENT. 77

One Part Cement, Three Parts Standard Sand.

1 days(l day in moist air, 6 days in water) 150-200 Ibs.

28 days(l day in moist air, 27 days in water) 200-300 Ibs.

23. Constancy of Volume. Pats of cement about three
inches in diameter, one-half inch thick at the centre, and taper-
ing to a thin edge, shall be kept in moist air for a period of
twenty-four hours.

(a) A pat is then kept in air at normal temperature and

observed at intervals for at least 28 days.-
(~b) Another pat is kept in water maintained as near 70

degrees F. as practicable, and observed at intervals

for at least 28 days.
(c) A third pat is exposed in any convenient way in an

atmosphere of steam, above boiling water, in a

loosely closed vessel for five hours.

24. These pats, to satisfactorily pass the requirements, shall
remain firm and hard and show no signs of distortion, check-
ing, cracking or disintegrating.

25. Sulphuric Acid and Magnesia. The cement shall not
contain more than 1.75 per cent, of anhydrous sulphuric acid
(SO 3 ), nor more than 4 per cent, of magnesia (MgO) .

SPECIFICATIONS OF THE CORPS OF ENGINEERS U. S. ARMY.

The great variations in requirements for cement upon work
under various officers of the Corps of Engineers of the U. S.
Army, shown in a table in the first olition of this book, have
been eliminated by referring the matter to a commission con-
sisting of Major William L. Marshall, Major Smith S. Leach
and Captain Spencer Cosby, w T hose report is given in No. 28 of
the Professional Papers of the Corps of Engineers U. S. Army.
The methods recommended for use in making tests have been
given in a preceding chapter. The specifications for cement
follow. The first specification is for American Portland
cement.

(1) The cement shall be an American Portland, dry and
free from lumps. By a Portland cement is meant the product
obtained from the heating or calcining up to incipient fusion
of intimate mixtures, either natural or artificial, of argil-
laceous with calcareous substances, the calcined product to
contain at least 1.7 times as much of lime, by weight, as of
the materials which give the lime its hydraulic properties,
and to be finely pulverized after said calcination, and there-
after addition or substitution for the purpose only of regulat-
ing certain properties of technical importance to be allowable

78 HANDBOOK FOR CEMENT USERS.

to not exceeding 2 per cent, of the calcined product.

(2) The cement shall be put up in strong, sound barrels,
well lined with paper, so as to be reasonably protected
against moisture, or in stout cloth or canvas sacks.
Each package shall be plainly labeled with the name of the
brand and of the manufacturer. Any package broken or con-
taining damaged cement may be rejected or accepted as a
fractional package, at the option of the United States agent
in local charge.

(3) Bidders will state the brand of cement which they pro-
pose to furnish. The right is reserved to reject a tender for
any brand which has not established itself as a high-grade.
Portland cement and has not for three years or more given
satisfaction in use under climatic conditions of exposure of
at least equal severity to. those of the work proposed.

(4) Tenders will be received only from manufacturers or
their authorized agents.

(The following paragraph will be substituted for para-
graphs 3 and 4 above when cement is to be furnished and
placed by the contractor. :

No cement will be allowed to be used except established
brands of high-grade Portland cement which have been made
by the same mill and in successful use under similar climatic
conditions to those of the proposed work for at least three
years.)

(5) The average weight per barrel shall not be less than
375 pounds net. Four -sacks shall contain one barrel of
cement. If the weight, as determined by test weighings, is
found to be below 375 pounds per barrel, the cement may be
rejected, or, at the option of the engineer officer in charge,
the contractor may be required to supply, free of cost to the
United States, an additional amount of cement equal to the
shortage.

(6) Tests may be made of the fineness, specific gravity,
soundness, time of setting and tensile strength of the cement.

(7) Fineness. Ninety-two per cent, of the cement must
pass through a sieve made of No. 40 wire, Stubb's gauge, hav-
ing 10,000 openings per square inch.

(8) Specific Gravity. The specific gravity of the cement,
as determined from a sample which has been carefully dried,
shall be between 3.10 and 3.25.

(9) Soundness. To test the soundness of the cement, at
least two pats of neat cement mixed for five minutes with 20
per cent, of water by weight shall be made on glass, each pat
about three inches in diameter and one-half inch thick at the
center, tapering thence to a thin edge. The pats are to be

SPECIFICATIONS FOR CEMENT. 79

kept under a wet cloth until finally set, when one is to be
placed in fresh water for twenty-eight days. The second pat
will be placed in water which will be raised to the boiling
point for six hours, then allowed to cool. Neither should
show distortion or cracks. The boiling test may or may not
reject, at the option of the engineer officer in charge.

^10) Time of Setting. The cement shall not acquire its
initial set in less than forty-five minutes and must have ac-
quired its final set in ten hours.

(The following paragraph will be substituted for the above
in case a quick-setting cement is desired:

The cement shall not acquire its initial set in less than
twenty or more than thirty minutes, and must have ac
quired its final set in not less than forty-five minutes, nor in
more than two and one-half hours.)

The pats made to test the soundness may be used in deter-
mining the time of setting. The cement is considered to have
acquired its initial set when the pat w T ill bear, without being
appreciably indented, a wire one-twelfth inch in diameter
loaded to weigh one-fourth pound. The final set has been
acquired when the pat will bear, without being appreciably
indented, a wire one twenty-fourth inch in diameter loaded to
weigh one pound.

(1) Tensile Strength. Briquettes made of neat cement^
after being kept in air for twenty-four hours under a wet*
cloth, and the balance of the time in water, shall develop
tensile strength per square inch as follows :

After seven days, 450 pounds; after twenty-eight days, 540
pounds.

Briquettes made of 1 part cement and 3 parts standard
sand, by weight, shall develop tensile strength per square
inch as follows:

After seven days, 140 pounds; after twenty-eight days, 220
pounds.

(In case quick-setting cement is desired, the following ten-
sile strengths shall be substituted for the above :

Neat briquettes: After seven days, 400 pounds; after twen-
ty-eight days, 480 pounds.

* Briquettes of 1 part cement to 3 parts standard sand:
After seven days, 120 pounds; after twenty-eight days, 180
pounds.)

(12) The highest result from each set of briquettes made
at any one time is to be considered the governing test. Any
cement not showing an increase of strength in the twenty-
eight-day tests over seven-day tests will be rejected.

(13) When making briquettes neat cement will be mixed

80 HANDBOOK FOR CEMENT USERS.

with 20 per cent, of water by weight, and sand and cement
with 12% per cent, of water by weight. After being thor-
oughly mixed and worked for five minutes, the cement or
mortar will be placed in the briquette mold in four equal
layers, and each layer rammed and compressed by thirty
blows of a soft brass or copper rammer three-quarters of an
inch in diameter (or seven-tenths of an inch square, w.ith
rounded corners), weighing 1 pound. It is to be allowed to
drop on the mixture from a height of about half an inch.
When the ramming has been completed, the surplus cement
shall be struck off and the final layer smoothed with a trowel
held almost horizontal and drawn back with sufficient
pressure to make its edge follow the surface of the mold.

(14) The above are to be considered the minimum require-
ments. Unless a cement has been recently used on work
under this office^ bidders will deliver a sample barrel for test
before the opening of bids. If this sample shows higher tests
than those given above, the average of tests made on subse-
quent shipments must come up to those found with the
sample.

(15) A cement may be rejected in case it fails to meet any
of the above requirements. An agent of the contractor may
be present at the making of the tests, or, in case of the failure
of any of them, they may be repeated in his presence. If the
.contractor so desires, the engineer officer in charge may, if he

deem it to the interest of the United States, have any or all
of the tests made or repeated at some recognized standard
testing laboratory in the manner herein specified. All ex-
penses of such tests to be paid by the contractor. All such
tests shall be made on samples furnished by the engineer
officer from cement actually delivered to hini.

Then follow specifications for natural hydraulic cement.

(1) The cement shall be freshly packed natural or Rosen-
dale, dry, and free from lumps. By natural cement is meant
one made by calcining natural rock at a heat below incipient
fusion, and grinding the product to a powder.

(2) The cement shall be put up in strong, sound barrels,
well lined with paper so as to be reasonably protected against
moisture, or in stout cloth or canvas sacks. Each package
shall be plainly labeled with the name of the brand and of
the manufacturer. Any package broken or containing dam-
aged cement may be rejected, or accepted as a fractional
package, at the option of the United States agent in local
charge.

(3) Bidders will state the brand of cement which they pro-
pose to furnish. The right is reserved to reject a tender for

( UNIVERSITY

\ OF

N^^ALIFOSSi^
SPECIFICATIONS FOR CEMENT. 81

any brand which has not given satisfaction in use under cli-
matic or other conditions of exposure of at least equal se-
verity to those of the work proposed.

(4) Tenders will be received only from manufacturers or
their authorized agents.

(The following paragraph will be substituted for para-
graphs 3 and 4 above when cement is to be furnished and
placed by the contractor. :

No cement will be allowed to be used except established
brands of high-grade natural cement which have been in suc-
cessful use under similar climatic conditions to those of the
proposed work.)

(5) The average net weight per barrel shall not be less than
30 pounds. (West of the Allegheny Mountains this may be
265 pounds.) . . . sacks of cement shall have the same
weight as 1 barrel. If the average net weight, as determined
by test weighings, is found to be below 300 pounds (265
pounds) per barrel, the cement may be rejected, or, at th
option of the engineer officer in charge, the contractor may be
required to supply free of cost to the United States an addi-
tional amount of cement equal to the shortage.

(6) Tests may be made of the fineness, time of setting, and
tensile strength of the cement.

(7) Fineness. At least 80 per cent, of the cement must
pass through a sieve made of No. 40 wire, Stubb's gauge,
having 10,000 openings per square inch.

(8) Time of Setting. The cement shall not acquire its ini-
tial set in less than twenty minutes and must have acquired
its final set in four hours.

(9) The time of setting shall be determined from a pat of
neat cement mixed for five minutes with 30 per cent, of
water by weight and kept under a wet cloth until finally set.
The cement is considered to have acquired its initial set when
the pat will bear, without being appreciably indented, a wire
one-twelfth inch in diameter iloaded to weigh one-fourth
pound. The final set has been acquired when the pat will
bear, without being appreciably indented, a wire one twenty
fourth inch ;n diameter loaded to weigh 1 pound.

(10) Tensile Strength. Briquettes made of neat cement
shall develop the following tensile strengths per square inch,
after having been kept in air for twenty-four hours under a
wet cloth and the balance of the time in water:

At the end of seven days, 90 pounds; at the end of twenty-
eight days, 200 pounds.

Briquettes made of one part cement and one part standard

82 HANDBOOK FOR CEMENT USERS.

sand, by weight, shall develop the following tensile strengths
per square inch :

After seven days, 60 pounds; after twenty-eight days, 150
pounds.

(11) The highest results from each set of briquettes made
at any one time is to be considered the governing test. Any
cement not showing an increase of strength in the twenty-
eight-day tests over the seven-day tests will be rejected.

(12) The neat cement for briquettes shall be mixed with 30
per cent, of water by weight, and the sand and cement with
17 per cent, of water by weight. After being thoroughly,
mixed and worked for five minutes the cement or mortar is
to be placed in the briquette mold in four equal layers, each
of which is to be rammed and compressed by thirty blows of
a soft brass or copper rammer three-fourths of an inch in
diameter (or seven-tenths of an inch square with rounded
corners), weighing 1 pound. It is to be allowed to drop on the
mixture from a height of about half an inch. Upon the com-
pletion of the ramming the surplus cement shall be struck off
and the last layer smoothed with a trowel held nearly hori-
zontal and drawn back with sufficient pressure to make its
edge follow the surface of the mold.

(13) The above are to be considered the minimum require-
ments. Unless a cement has been recently used on work
under this office, bidders will deliver a sample barrel for test
before the opening of the bids. Any cement showing by sam-
ple higher tests than those given must maintain the average
so shown in subsequent deliveries.

(14) A cement may be rejected which fails to meet any of
the above requirements. An agent of the contractor may be
present at the making of the tests, or, in case of the failure
of any of them, they may be repeated in his presence. If the
contractor so desires, the engineer officer may, if he deems it
to the interest of the United States, have any or all of the
tests made or repeated at some recognized standard testing
laboratory in the manner above specified. All expenses of
such tests shall be paid by the contractor, and all such tests
shall be made on samples furnished by the engineer officer
from cement actually delivered to him.

Puzzolan or slag cement is to fulfill the following condi-
tions :

(1) The cement shall be a puzzolan of uniform quality,
finely and freshly ground, dry, free from lumps, made by
grinding together without subsequent calcination granulated
blast-furnace slag with slaked lime.

(2) The cement shall be put up in strong sound barrels well

SPECIFICATIONS FOR CEMENT. , 83

lined with paper, so as to be reasonably protected against
moisture, or in stout cloth or canvas sacks. Each package
shall be plainly labeled with the name of the brand and of
the manufacturer. Any package broken or containing dam
aged cement may be rejected, or accepted as a fractional
package, at the option of the United States agent in local
charge.

(3) Bidders will state the brand of cement which they 'pro-
pose to furnish. The right is reserved to reject a tender for
any brand which has not given satisfaction in use under cli-
matic or other conditions of exposure of at least equal sever-
ity to those of the work proposed, and for any brand from
cement works that do not make and test the slag used in the
cement.

(4) Tenders will be received only from manufacturers or
their authorized agents.

(The following paragraph will be substitued for para-
graphs 3 and 4 above when cement is to be furnished and
placed by the contractor.

No cement will be allowed to be used except established
brands of high-grade puzzolan cement which have been in
successful use under similar climatic conditions to those of
the proposed work and which come from cement works that
make the slag used in the cement.)

(5) The average weight per barrel shall not be less than 330
pounds net. Four sacks shall contain 1 barrel of cement. If
the weight as determined by test weighings is found to be
below 330 pounds per barrel, the cement may be rejected or,
at the option of the engineer officer in charge, the contractor
may be required to supply, free of cost to the United States,
an additional amount of cement equal to the shortage.

(6) Tests may be made of the fineness, specific gravity,
soundness, time of setting, and tensile strength of the cement.

(7) Fineness. Ninety-seven per cent, of the cement must
pass through' a sieve made of No. 40 wire, Stubb's gauge, hav-
ing 10,000 openings per square inch.

(8) Specific Gravity. The specific gravity of the cement,
as determined from a sample which has been carefully dried,
shall be between 2.7 and 2.8.

(9) Soundness. To test the soundness of cement, pats of
neat cement mixed for five minutes with 18 per cent, of water
by weight shall be made on glass, each pat about 3 inches in
diameter and one-half inch thick at the center, tapering
thence to a thin edge. The pats are to be kept under wet
cloths until finally set, when they are to be placed in fresh

84 HANDBOOK FOR CEMENT USERS.

water. They should not show distortion or cracks at the end
of twenty-eight days.

(10) The cement shall not acquire its initial set in less than
forty-five minutes and shall acquire its final set in ten hours.
The pats made to test the soundness may be used in deter-
mining the time of setting. The cement is considered to have
acquired its initial set when the pat will bear, without being
appreciably indented, a wire one-twelfth inch in diameter
loaded to one-fourth pound weight. The final set has been
acquired when the pat will bear, without being appreciably
indented, a wire one-twenty-fourth inch in diameter loaded
to 1 pound weight.

(11) Tensile Strength. Briquettes made of neat cement,
after being kept in air under a wet cloth for twenty-four
hours and the balance of the time in water, shall develop
tensile strengths per square inch as follows :

After seven days, 350 pounds; after twenty-eight days, 500
pounds.

Briquettes made of one part cement and three parts stand-
ard sand by weight shall develop tensile strength per square
inch as follows:

After seven days, 140 pounds; afetr twenty-eight days, 220
pounds.

(13) When making briquettes neat cement will be mixed
with 18 per cent, of water by weight, and sand and cement
with 10 per cent, of water by weight. After being thoroughly
mixed and worked for five minutes the cement or mortar will
be placed in the briquette mold in four equal layers and each
layer rammed and compressed by thirty blows of a soft brass
or copper rammer, three-quarters of an inch in diameter or
seven-tenths of an inch square, with rounded corners, weigh-
ing 1 pound. It is to be allowed to drop on the mixture from
a height of about an inch. When the ramming has been com-
pleted the surplus cement shall be struck off and the final
layer smoothed with a trowel held almost horizontal and
drawn back with sufficient pressure to make its edge follow
the surface of the mold.

(14) The above are to be considered the minimum require-
ments. Unless a cement has been recently used on work
under this office, bidders will deliver a sample barrel for test
before the opening of bids. If this sample shows higher tests
than those given above, the average of tests made on subse-

SPECIFICATIONS FOR CEMENT. 85

quent shipments must come up to those found with the
sample.

(15) A cement may be rejected in case it fails to meet any
of the .above requirements. An agent of the -contractor may
be present at the making of the tests, or, in case of the failure
of any of them, they may be repeated in his presence. If
the contractor so desires the engineer officer in charge may,
if he deems it to the interest of the United States, have any
or all of the tests made or repeated at some recognized test-
ing laboratory in the manner herein specified, all expenses of
such tests to be paid by the contractor. All such tests shall
be made on samples furnished by the engineer officer from
cement actually delivered to him.

The only criticisms of importance regarding the preceding
specifications which have appeared are regarding the amount
of water used in making briquettes, the specific gravity, and
the fineness for the Pacific coast. Mr. E. Duryee calls atten-
tion to the fact that to produce the normal consistency of
mortar according to Russian and other foreign specifications,
the amount of water must be varied according to the brand
of cement, and even according to the age of the shipment
from which sample is taken, and that the amount required is
almost always more than 20 per cent, by weight, sometimes
running as high as 30 per cent.; that very finely ground
cement may have a specific gravity of less than 3.1.

U. S, NAVY DEPARTMENT SPECIFICATIONS.

Quality. The cement to be of the best grade or quality.

Aeration. Contractor shall give a certificate to the effect
that the cement furnished has been seasoned or subjected to
aeration for at least thirty days before leaving the works.

Packing. The cement is to be packed in strong and well
coopered barrels, lined with moisture-proof paper. The gross
weight of the barrels is not to be less than 400 pounds; the
weight of the cement is not to be less than 375 pounds.

Storage. Immediately upon, receipt, the cement is to be
stored in a dry, well-covered and well-ventilated place and
thoroughly protected from the weather.

Chemical Analysis. On every lot of eight hundred barrels
or more, the contractor shall supply an abstract of the chem-
ical analysis of a mixed sample of the cement taken from
any ten barrels of the lot. Specific gravity shall not be less
than 3.

Samples for Test. Samples of the cement are to be taken
from the interior. of the barrels with a suitable instrument.

HANDBOOK FOR CEMENT USERS

Samples are to be taken from every fifth barrel, in lots of
twenty or more, up to one hundred barrels. If less than one
hundred barrels are to be tested, the samples are to be taken
from at least three barrels. The separate quantities so taken
shall be mixed thoroughly together, while dry, and the com-
pound regarded as the sample for test.

Fineness. Ninety-five per cent, by weight must pass
through a No. 100 sieve having 10,000 meshes per square inch,
the wire tp be No. 40 Stubb's wire gauge, and 75 per cent, by
weight must pass through a No. 200 sieve having 40,000
meshes per square inch, the wire to be No. 48 Stubb's wire
gauge.

Setting Qualities. Cakes of the paste, mixed as specified
in the following paragraph, are to be molded on glass; these
cakes to be circular in shape, three inches in diameter, one-
half inch thick in center and drawn down to one-eighth inch
at circumference. One cake is to set in air, and one cake is
to set immersed in water. Two wires are to be used to de-
termine setting qualities: The first, called wire A, is to be
one-twelfth inch in diameter at the lower extremity and
loaded with 14 H>- a t the upper end; and the second, called
wire B, is to be one twenty-fourth inch in diameter at the
lower extremity and loaded with 1 Ib. at the upper end.
Cement will be considered as quick-setting if it bears needle
A without making an indentation during any time between one
hour and six hours after having been mixed. The slow-set-
ting cement must have its final set at the end of eight hours
that is, it must bear needle B without being indented by it.

Neat Cement Paste for Test. All neat cement for test is
to be mixed on glass with clean, fresh water of a temperature
between 60 degrees and 70 degrees F. ; the quantity of the
water to vary between 20 per cent, and 25 per cent, by weight
of the quantity of cement used.

Change of Volume. A small quantity of the same cement
specified above is to be mixed with only sufficient water to
give it the consistency of wet sand, and it is to be immedi-
ately pressed into a glass tube of about one-half inch in diam-
eter. Within two or three days any swelling will be shown
by the glass bursting; or shrinkage, by the cement becoming"
loose in tube; either defect is a cause for rejection of the
cement.

Checking and Cracking. Three cakes of neat cement are to
be prepared as specified in paragraph for setting quality.
One cake, after having set hard on the glass on which it was
moulded, is to be placed in cold water and examined from
time to time during a period covering seven or twenty-seven

SPECIFICATIONS FOR CEMENT. 87

days. If it warps, checks on surface, cracks at the edge, or
leaves the glass, such defects are cause for the rejection of
the cement. One cake is to be placed in air, and one cake in
water kept at a temperature of 212 degrees for 24 hours and
similarly examined.

Sand. The sand that is to be mixed with the neat cement
for compounding mortar briquettes for test shall be No. 4
standard crushed quartz, passing through a No. 20 sieve (400
meshes to the square inch), wire of No. 31 Stubb's wire gauge.

Making the Briquettes. Neat Briquettes: moisten the ce-
ment with 20 per cent, to 22 per cent, of water, mixing and
kneading it quickly by hand, using rubber gloves for protec-
tion. When thoroughly worked fill the molds at once, hav-
ing first wiped them on the inside with an oily cloth to pre-
vent sticking. Mortar briquettes : one part by weight of
cement to three parts by weight of the kind of sand specified
in the preceding section shall be thoroughly incorporated
while dry and then moistened with 10 per cent, or 12 per cent,
of water in the manner specified above for neat briquettes.
Both the neat and mortar briquettes shall be prepared by the
Bohme Hammer Apparatus, which is a tilt hammer with
automatic action. The hammer is driven by a cam wheel of
ten cams actuated by a simple gearing. The steel hammer
weighs 4!/2 Ibs., and when the intended number of blows has
been delivered the mechanism is automatically checked, the
proper setting having been made for this purpose before be-
ginning the work. The number of blows for each briquette
shall be 150. The briquettes while drying in air should be
covered with a damp cloth to prevent rapid surface drying,
and to conduce to a uniform set.

Tensile Strength. The neat briquettes prepared as speci-
fied above, shall stand a minimum tensile strain per square
inch, without breaking, as follows :

For 12 hrs. in air and 12 hrs. in water 200 Ibs.

For 1 day in air and 6 days in water 550 Ibs.

For one day in air and 27 days in water 650 Ibs.

The mortar briquettes prepared as specified above, shall
stand a minimum tensile strain per square inch, without
breaking, as follows :

After 12 hrs. in air and 12 hrs. in water 150 Ibs.

After 1 day in air and 6 days in water 200 Ibs.

After 1 day in air and 27 days in water 250 Ibs.

Notes. The boiling water test is designed to ascertain the
durability of the cement, and is intended to show in a few
hours what would take a long period otherwise. This test is
supposed to show. whether an excess of free lime is in the

88 HANDBOOK FOR CEMENT USERS.

cement. Some cements stand well for short periods, but dis-
integrate after three or four months, due to an excess of
free lime.

In making the mortar bricks, the sand and cement should
be thoroughly mixed while dry, and then the specified per-
centage of water added quickly.

The neat tests are of less value than those of briquettes
made of sand and cement. The fineness of cement is impor-
tant ; for the finer it is the more sand can be used with it.

Good cement should be a uniform bluish gray color through-
out; yellow checks or places indicate an excess of clay or-
that the cement has not been sufficiently burned; and it is
then probably a quick-setting cement of low specific gravity
and deficient strength.

Cement that will stand a high test for seven days may have
an excess of lime, which will cause it to deteriorate. The
twenty-eight day test is, therefore, very useful.

The trip hammer machine for making briquettes removes
all variability in their preparation.

The most dangerous feature in Portland cement is the pres-
ence of too much magnesia and an excess of free lime, the
latter indicated by the cracks and distortions in the test
cakes, and the former in the deficiency of tensile strength of
the briquettes. Over 3 per cent, of magnesia is excessive and
dangerous.

The cement that is to be made into briquettes and cakes
shall not be sifted, but it is to be used exactly as it comes
from the barrels.

Five briquettes should be broken to test the tensile
strength, and the extra variation from the mean of the five
should not be over 15 per cent.

The test for change of volume is very important, for expan-
sion in any work into which the cement enters would be fatal
to reliability.

The test cakes should be made by rolling the cement into
balls and then flattening.

The expanding, cracking and disintegrating of the cement
is technically called blowing.

If the cake at the end of three days in water shows no sign
of cracking or disintegrating at the edges, it can be consid-
ered safe.

In examining cakes for cracks, the fine hair cracks found on
the surface, that cross and recross each other, are not due to
blowing, but are merely the result of changes of temperature.
The cracks due to blowing are wedge shaped, running from
the center and usually accompanied by a certain amount of
disintegration, especially at the edges.

SPECIFICATIONS FOR CEMENT. 89

Either Fairbanks or Riehle machines should be used for
breaking briquettes in a test for tensile strength.

The weight per barrel and the weight of barrel vary and
the specification given above is a valuable one. Thus in 25
barrels of standard American and foreign cements the aver-
age weight of cement per barrel of the seven brands tested
varied from 370 to 387 pounds, the weight of barrel varied
from 21 to 29 pounds, and the weight of unbroken package
varied from about 394 to 410 pounds.

SPECIFICATIONS OF RAILROADS.

For railroad work the specifications have heretofore been
very discordant. Some sample specifications and abstracts
from specifications for railroads in different parts of the
country are given, showing the best practice for this class of
work. The rapidly increasing use of Portland cement for
railroad structures demanded material improvement in speci-
fications, and such improvement has been quite marked in the
last year or two.

The following are the specifications for cement of the engi-
neering department of the New York Central & Hudson River
railroad :

Tests.
Sieve

No. 50 of 2,500 meshes per square
inch of No. 35 Stubbs' wire gauge.

Light Wire

Cement to bear A " diameter wire,
weight 4 oz., without imprint, in
not less than

Hfitnj Wire

Cement to bear 2," diameter wire,
weight 1 lb., without imprint, in
not less than

('//'<-/cinq. Cracking and Hot

Tett*-

Flat cakes or "pats" of stiff plas-
tic neat cement paste, two to three
inches diameter by half inch thick-
ness, with thin edges to be im-
mersed in water not less than two
days.

Natural Bock.
95 per cent, "fine"

25 minutes.
50 minutes.

Must not crack nor
become contorted
along the edges.

Portland.
97 per cent- "Fine"

25 minutes.
50 minutes.

Shall withstand with-
out cracking a tem-
perature of steam or
water at 212 Fahr.
after 24 hours set in
cold water.

Tensile Strength. Standard briquettes of one square inch
of breaking section. Stress applied at a uniform rate, from
zero, of about 400 Ibs. per minute.

Neat. Natural Rock. Portland.

1 hour in air 23 hours in water 60 Ibs. 100 Ibs.

24 hours in air 6 days in water 90 "

24 13 115 "

24 " 20 132 "

24 27 " .143 "

Average 108 Ibs. 314 Ibs.

350
410
450

90 HANDBOOK FOR CEMENT USERS.

Standard Sand. 1 to 2. 1 to 3.

1 hour in air 23 hours in water 27 Ibs. 60 Ibs.

24 hours in air 6 days in water 35 " 90

24 13 43 " 115 "

24 " 20 50 " 132 "

25 27 56 " 143 "

Average 42 Ibs. 108 Ibs.

Weight. Natural fiocfc. Portland.

1 barrel shall contain of neat

cement, not less than 300 Ibs. 386 Ibs.

The following are selected from the standard specifications
of the maintenance of way department of the Pennsylvania
Railroad Company:

Sampling. The cement for testing shall be selected by tak-
ing from each of six well-distributed barrels in each car-load
received, sufficient cement to make five to ten briquettes;
these six portions, after being thrown together and thorough-
ly mixed will be assumed to represent the average of the
whole car-load.

Fineness. Not more than 10 per cent, of any cement shall
fail to pass through a No. 50 sieve (2,500 meshes per square
inch, wire to be No. 35 Stubb's wire gauge), and not more
than 10 per cent, of Portland cement shall fail to pass a No.
100 sieve.

Cracking. Neat cement mixed to the consistency of stiff
plastic mortar and made in the shape of flat cakes, 2 or 3
inches in diameter and one-half inch thick with thin edges,
when hard enough shall be immersed in water for at least
two days. If they crack along the edges or become contorted,
the cement is unfit for use.

Tensile Strength. The test for tensile strength shall be
made with briquettes of standard form recommended by the
Amercian Society of Civil Engineers, in molds furnished by
the engineer of maintenance of way. They must have an av-
erage tensile strength not less than that given in the table
below :

1 Day 1 Week. 4 Weeks.
Natural Hydraulic Cement

Neat 70 95 150

1 sand to 1 cement 50 120

2 sand to 1 cement 30 60

American and Foreign Portland Cement

Neat 100 320 450

2 sand to 1 cement 120 175

Proportion of Water. The. proportion of water used in
making briquettes varies with the fineness, age and other
conditions of the cement and the temperature of the air, but
is approximately as follows: Neat cement, Portland, 20 per
cent, to 30 per cent. ; 1 sand, 1 cement, about 15 per cent, total
weight ; 2 sand, 1 cement, about 12 per cent, total weight.

SPECIFICATIONS FOR CEMENT. 91

Mixing. The cement and sand in proper proportions shall
be mixed dry and all the water specified added at one time,
the mixing to be as rapid as possible to secure a thorough
mixture of the materials, and the mortar, when stiff and plas-
tic, to be firmly pressed to make it solid in the molds with-
out ramming, and struck off level.

Molding. The molds to rest directly on glass, slate, or
other non-absorbent material. As soon as hard enough,
briquettes are to be taken from the molds and kept covered with
a damp cloth until immersed. In the one-day test, briquettes
shall remain on the slab for one hour after being removed
from mold and twenty- three hours in water. In one week
or more test, briquettes shall remain in air one day after
being removed from molds and balance of time in water.
Briquettes are to be broken immediately after being taken
from the water. Stress to be applied at a uniform rate of 400
pounds per minute, starting each time at zero. No record to
be taken of briquettes breaking at other than the smallest
section.

Sand. The sand used in test shall be clean, sharp, and dry,
and be such as shall pass a No. 20 sieve (400 meshes per
square inch, wire to be No. 28 Stubb's wire gauge), and to be
caught on a No. 30 sieve (900 meshes per square inch, wire to
be No. 31 Stubb's wire gauge).

Water. Ordinary fresh, clean water having a temperature
between 60 degrees and TO degrees F., shall be used for the mix-
ture and immersion of all samples.

Proportions. The proportions of cement and sand and
water shall in all cases be carefully determined by weight. In
preparing briquettes for test, sufficient material is to be
taken to make one briquette at a time, and enough of water
added to make a stiff paste as above stated.

The temperature of the testing room shall not be below 47
degrees F.

For concrete work to take the place of stone masonry, Mr.
V. K. Hendricks, now an engineer on the Baltimore & Ohio
Railway, makes the following requirements in addition to those
made above for ordinary work.

Portland Cement. The cement shall be a true Portland
cement, made by calcining a proper mixture of calcareous and
clayey earths, and if desired a certified statement shall be fur-
nished of the chemical composition of the cement, and the
raw materials from which it is manufactured. Without writ-
ten authority no Portland cement will be accepted which con-
tains more than two per cent, of magnesia in any form.

92 HANDBOOK FOR CEMENT USERS.

The fineness shall be such that at least ninety-nine per cent,
shall pass through a standard brass cloth sieve of 50 meshes
per linear inch, at least ninety per cent, shall pass through
a sieve of 100 meshes per linear inch, and at least seventy
per cent, shall pass through a sieve of 200 meshes per linear
inch.

Samples for testing may be taken from each and every bar-
rel delivered.

Specimens prepared from neat cement shall after seven
days develop a tensile strength of not less than 450 pounds
per square inch. Specimens prepared from a mixture of one.
part cement and three parts sand, by weight, shall, after
seven days, develop a tensile strength of not less than 160
pounds per square inch.

Cement mixed neat with about 27 per cent, of water to form
a stiff paste, shall, after thirty minutes, be appreciably in-
dented by the end of a wire one-half inch in diameter,
loaded to weigh one-quarter pound. Cement made into thin
cakes on glass plates shall not crack, scale or warp under the
following treatment : Three pats shall be made and allowed
to harden in moist air at from 60 to 70 degrees F.
One of these shall be subjected to water vapor at 176 de-
grees F. for three hours, after which it shall be im-
mersed in hot water for forty-eight hours; another shall be
placed in water from 60 to 70 degrees F., and the third be left
left in moist air.

Natural Cement. Natural cement shall be of such fineness
that not less than 90 per cent, shall pass through a standard
brass cloth sieve of 50 meshes per linear inch.

Neat cement briquettes shall have a tensile strength of not
less than 120 pounds after remaining one day in air and six
days in water and shall gain in strength with age. Briquettes
of one part cement and one part sand, by weight, shall at
the end of seven days develop a tensile strength of not less
than 85 pounds per square inch.

A boiling test will also be made by mixing cakes as above,
placing them at once in cold water, raising the temperature of
the water to boiling in about an hour, continuing boiling for
three hours, and then examining for checking and softening.

The specifications of the Philadelphia & Beading Kailway
Company for cement are as follows :

All cements purchased by this company must conform to the
following requirements :

(1) Sampling. A one-pound sample will be taken from each
of five barrels or bags in every carload or fraction thereof.
These five portions will be thoroughly mixed and the accept-

SPECIFICATIONS FOR CEMENT.

ance or rejection of the entire carload will depend upon the
results of the examination of this sample.

(2) Fineness. No. 50, 100, and 200 sieves made of brass wire
cloth, having approximately 2,400, 10,200, and 35,700 meshes
per square inch, respectively, with diameter of wire of .0090,
.0045, and .0020 inch, respectively, shall retain not exceeding
the following residue:

Portland Cement. Natural Cement,

No. 50 sieve 3 per cent 2 per cent

No. ] 00 ' ' 10 per cent 15 per cent

No. 200 " 30 per cent 35 per cent

(3) Composition. Magnesia (MgO), not exceeding, Portland
5 per cent., Natural 5 per cent. Sulphuric acid (SO 3 ), not ex-
ceeding, Portland 2 per cent., Natural 2% per cent.

(4) Specific Gravity. Not less than, Portland 3.05, Nat-
ural 2.90.

(5) Time of Setting. Neat cement of normal consistency, at
temperature between 60 degrees F. and 70 degrees F., shall con-
form to the following time of setting, as determined by Gil-
more's wire test:

Portland. Natural.

Initial set, not less than 30 min. 10 min.

Hard set, not less than 30 min.

(6) Constancy of Volume. Pats of neat cement of normal
consistency, one-half inch thick, with thin edges, immersed in
water after hard set, shall show no sign of checking or disin-
tegration.

(7) Tensile Strength. Briquettes of cement, one square inch
in cross section shall develop the following tensile strength :

Portland. Natural.

Neat, 24 hours, (in water after hard

set) 175 Ibs. 100 Ibs.

Neat, 7 days (1 day in air, 6 days in

water) 450 Ibs. 200 Ibs.

Neat, 20 days (1 day in air, 27 days

in water) 500 Ibs. 300 Ibs.

Portland Natural

one part cement one part cement

and three part and two parts

sand. sand.

Sand, 7' days (1 day in air, 6 days in

water) 170 Ibs. 115 Ibs.

Sand, 20 days (1 day in air, 27 days

in water) 240 Ibs. 200 Ibs.

(8) Briquette Making. Six ounces of the cement will be
quickly and thoroughly kneaded up with water in such propor-
tions that a ball of the mixture taken at once and dropped upon
the slab from a height of three feet shall neither flatten ma-
terially nor crack. This proportion of water will then be
added all at once to another batch of the cement and quickly

94 HANDBOOK FOR CEMENT USERS.

worked up until the mass is homogeneous. The paste will then
be pressed into standard molds without ramming, and struck
off upon both sides with the trowel. Pats of neat cement for
determining the time of setting and constancy of volume will
be made from the same paste.

(9) Sand Briquettes. Sand and cement to be thoroughly
mixed dry, and all the water required to be added at once.
The sand used shall consist of crushed quartz which will pass
a No. 20 sieve and be retained by a No. 30 sieve. As soon as
the briquettes are hard enough to handle they are to be re-
moved from the molds and kept m a damp closet or covered
with damp cloths until placed in water. The briquettes to be
broken in test machine immediately after removal from water.

(10) Rejected Cement. Cement not in accordance with
above' specifications, to be returned at expense of shipper, and
in case of rejection, sample upon which test is based to be held
for one month at the disposal of the shipper.

The specifications of the Chicago & Alton Railway Company
for cement are as follows:

Weight. All cement purchased by the railway company
shall be packed in barrels or in sacks, four sacks per barrel for
Portland, and two or three sacks per barrel for Natural cement ;
380 Ibs. net of Portland cement and 265 Ibs. net of Natural
cement shall be considered a barrel, and all cement accepted
shall be paid for on this basis.

Damaged Cement. Any packages in which the cement has
been damaged by moisture before delivery to the company, will
be rejected, and, if numerous, the whole carload or boatload
may, at the discretion of the chief engineer, be rejected with-
out further test.

Rejected Cement. All cement rejected by the company,
through failure to stand the following tests, or for any other
good and sufficient reason, shall be at once removed at the ex-
pense of the contractor.

Contract Work. Cement used on contract work for the com-
pany shall be subject to the same requirements and tests as
that purchased direct by the company and the contractor will
be required to keep on hand a supply of accepted cement, suf-
ficient to keep the work going until more is accepted.

Sampling. From 5 per cent, to 20 per cent, of the packages
will be sampled for testing purposes. These samples may be
tested separately, or mixed and then tested, at the discretion
of the chief engineer.

Test Requirements. The cement shall equal the following
requirements :

SPECIFICATIONS FOR CEMENT.

KIND OF
CEMENT

FINENESS.

TENSILE STRENGTH.

POUNDS PER SQUARE INCH.

TIME OP SETTING.

PER CENT. PASS
ING SIEVES.

NEAT,

1 C, TO 1 S.
BY VOLUME

1 C. TO 3 S.
BY VOLUME

INITIAL

FINAL.

50 minutes
to 10 hours.

No. 50

No. 100

7 Da

28 Da

7 Da

28 Da

7 Da

28 Da

Portlar.d

400

480

150

200

30 minutes
to 5 hours.

Natural

100

150

110

10 minutes
to 2 hours.

20 minutes
to 3 hours.

Thin pats or cakes of neat cement allowed to take final set
in moist air must withstand indefinite exposure in water or
air at any temperature, to which the cement may be exposed in
work, without giving any evidence of swelling, checking or
warping out of shape, or softening.

Pats of neat Portland cement allowed to take final set in
moist air must withstand exposure for six hours in steam at
atmospheric pressure above the surface of boiling water, or
three hours in steam and three hours in boiling water, with-
out becoming soft or showing any signs of swelling, checking,
or warping out of shape. Pieces of briquettes broken in ten-
sile tests of Portland cement, either neat or mortar, must re-
main hard and sound after the same exposure to steam or
boiling water as specified for the pats.

Consistency of Mixing. The briquettes for tensile tests shall
be mixed with sufficient water to render the mortar plastic, so
that the moulds can be easily filled by thumb pressure.

The neat pats for setting and soundness test should be mixed
somewhat wetter than the briquettes, so that they can be
readily finished smooth with thin edges on glass.

The following table gives the amounts of water usually re-
quired to accomplish these results :

WATER REQUIRED IN PER CENT. BY WEIGHT OF TOTAL

DRY INGREDIENTS, i- e.

CEMENT AND SAND.

KIND OF CEMENT

OR BRIQUETTE

FOR PATS.

NEAT

1 c. to 1 SD.

1 C. to 3SD.

NEAT.

20 to 24

8 to 12

28 to 30

Natural

32 to 36

14 to 18

38 to 42

96 HANDBOOK FOR CEMENT USERS.

Explanations and Definitions. The briquettes for tensile
test shall set twenty-four hours in moist air and the remainder
of the time in water of 55 degrees to 65 degrees F.

The sieves for fineness test shall be standard No. 50 and No.
100 sieves, i. e., having 50 and 100 meshes per linear inch, re-
spectively.

Initial set shall mean that the pat supports % of a pound
on a wire 1-12 inch in diameter, and final set that it supports
one pound on a wire 1-24 inch in diameter, without indentation.

In making the mortar briquettes the proportions by volume
shall be on the basis of 100 Ibs. per cubic foot for the sand,
100 Ibs. for the Portland cement, 67 Ibs. for the Natural cement.

Sand. The sand used in making the mortar briquettes shall
be clean and shall be screened through a No. 8 sieve, 8 meshes
per linear inch, and caugkt on a No. 50 sieve, 50 meshes per
linear inch.

Uniformity of Product. When a given brand of cement has
been tested for some time and found to be fairly uniform ID
its action under the different tests, a sudden wide variation
from this normal action in any kind of test shall be looked
upon with suspicion and should lead to more extended and
longer time tests.

The chief engineer shall have the right to make any other
tests, or use any other means in his power, to gain informa-
tion as to the quality of cement, and reserves the right to reject
any cement which he is not fully satisfied is suitable for the
work for which it is intended.

CONCRETE ARCHES.

Three specifications are given for the cement for concrete
arch construction to show the variations in requirements in
first-class structures. The specifications for the work are given
in a subsequent chapter. The first is for a concrete bridge at
Pine Road over Pennypack Creek, Philadelphia, built in 1893,.
Monier construction, and said to be the first concrete arch
high'way bridge in the United States. It was designed and
construction superintended by the Bureau of Highways of
Philadelphia. After careful examination of various brands of
cement a single brand of German Portland cement was speci-
fied and used, without further specification.

The second, for a Melan arch bridge constructed at Topeka,
Kansas, in 1896, is as follows: The Portland cement shall be
a true Portland cement, made by calcining a proper mixture
of calcareous and clayey earths; and the contractor shall fur-

SPECIFICATIONS' FOR CEMENT. 97

nisk one or more certified statements of the chemical compo-
sition of the cement and of the raw materials from which it
is manufactured. Only one brand of Portland cement shall
be used on the work, except with permission of the superin-
tendent, and it shall in no case contain more than 2 per cent,
of magnesia in any form. The fineness of the cement shall be
such that at least 98 per cent, shall pass through a standard
brass cloth sieve of 74 meshes per linear inch, and at least 95
per cent, shall pass through a sieve of 100 meshes per linear
inc)i. Samples for testing may be taken from each and every
barrel delivered as superintendent may direct. Tensile tests
wiU be made on specimens prepared and maintained until
tested at a temperature of not less than 60 degrees F. Each
specimen shall have an area of 1 square inch at the breaking
section, and, after being allowed to harden in moist air for
twenty -four hours, shall be immersed and retained under water
until tested. The sand used in preparing the test specimens
shall be clean, sharp, crushed quartz, retained on a sieve of 30
meshes per lineal inch, and shall be furnished by contractor.
No more than 23 to 27 per cent, of water by weight shall be
used in preparing the test specimens of neat cement and in
making the test specimens, 1 of cement to 3 of sand, no more
than 11 or 12 per cent, of water shall be used. Specimens pre-
pared from neat cement shall after seven days develop a tensile
strength not less than 400 pounds per square inch. Specimens
prepared from a mixture of 1 part cement to 3 parts sand (by
weight), shall, after seven days, develop a tensile strength of
not less than 140 pounds per square inch, and after twenty-
eight days not less than 200 pounds per square inch. Speci-
mens prepared from a mixture of 1 part cement and 3 parts
sand (by weight), and immersed after twenty-four hours in
water to be maintained at 176 degrees F. shall not swell or
crack, and shall after seven days develop a tensile strength
of not less than 140 pounds per square inch. Cement mixed
neat with about 27 per cent, of water to form a stiff paste,
shall, after 30 minutes, be appreciably indented by the end of
a wire 1-12 inch in diameter, loaded to weigh 14 pound. Cement
made into thin cakes on glass plates shall not crack, scale or
warp under the following treatment: Three pats shall be
made and allowed to harden in moist air at from 60 degrees
to 70 degrees F. ; one of these shall be subjected to water vapor
at 176 degrees F. for three hours, after which it shall be im-
mersed in hot water for forty -eight hours; another shall be
placed in water a't from 60 degrees to 70 degrees F., and the
third shall be left in moist air. Samples of 1 to 2 mortar and
of concrete shall be made and tested from time to time as

98 HANDBOOK FOR CEMENT USERS.

directed by the superintendent. All cement shall be housed
and kept dry till wanted in the work.

The third specification given is for Melan arch bridges con-
structed in Indianapolis, in 1900.

All cement used for the arches shall be either (one of four
brands of German and Danish cement mentioned). Cement
for the other parts of the work shall be such as is satisfactory
for cement sidewalks, class "B," standard specifications form
Q, and must also conform to the general specifications for
cement (formH).

The specifications for class "B" sidewalks is as follows :
For class "B" sidewalks, the following brands of cement
shall be allowed: (Fourteen German, Danish and Belgian
cements and four American Portland cements are named).

The general specificatipns for cement (form H) are as fol-
lows:

1. Any cement without maker's name and brand on the
barrel or package will be rejected without test.

2. All required samples for testing must be furnished by the
contractor.

3. A supply of accepted cement must be kept on hand by
the contractor.

4. Rejected cement must be removed by the contractor from
the work at once.

5. Cement shall be subject to reinspection, test and rejec-
tion, if necessary, at any time.

6. All desired information as to place, materials and method
of manufacture, and name of makers and agents, shall be fur-
nished whenever desired by the Board of Public Works and
City Engineer.

7. Hydraulic cement shall be of the best quality of natural
cement, newly manufactured, well housed and preserved dry
until required for use. It shall be finely ground, not less than
80 per cent, passing through a sieve of 80 meshes to the linear
inch. When tested neat in the usual manner, it must stand a
proof tensile strain of 60 pounds per square inch on specimens
allowed to set 30 minutes in air and twenty-four (24) hours
under water. It shall also stand 100 pounds when allowed to
set one day in air and six days in water, and 150 pounds per
square inch when allowed to set one day in air and 27 days in
water. When mixed one part of cement and two parts of sand>
by weight, it shall stand 30 pounds when allowed to set one
day in air and 27 days in water. Cakes one-half inch in thick-
ness, with thin edge, shall show no cracks or softness after

SPECIFICATIONS FOR CEMENT. 99

seven days in water. Certificates of inspection at the mills
that the cement fulfills these requirements may be required by
the Board of Public Works, the cost of said inspection to be
paid by the contractor.

8. Portland cement for concrete, plastering catch-basins and
other miscellaneous purposes, shall be equal to the best quality
of Portland cement made from selected rock, carefully manu-
factured, which has been well seasoned and housed and kept
dry until required for use. It shall be finely ground, not less
than 90 per cent, passing through a sieve of 80 meshes to the
lineal inch. Neat cement shall not set in less than one hour
unless quick setting is specifically called for, when it shall not
set in less than 10 minutes. When tested in the usual man-
ner it must stand a proof tensile strain of 125 pounds per
square inch when allowed to set in air until hard, and the re-
mainder of 24 hours in water. It shall also stand 350 pounds
when allowed to set one day in air and six days in water, and
500 pounds when allowed to set one day in air and 27 days in
water. When one part of cement is mixed with three parts
of sand, by weight, it shall stand 100 pounds per square inch
when allowed to set one day in air and six days in water, and
200 pounds when allowed to set one day in air and 27 days in
water. Cakes one-half inch in thickness, with thin edges, shall
show no cracks, blowing or softness after seven days in water.

9. Portland cement for sidewalks and other work requiring
special qualities shall be equal to the best quality of German
Portland cement, made from an artificial mixture of proper
materials and according to the best methods of mixing, burn-
ing and grinding. It must be well seasoned and have been
thoroughly well protected from injury by moisture and other-
wise. It shall be finely ground, not less than 95 per cent, pass-
ing through a sieve of 80 meshes to the lineal inch, and 90 per
cent, through a sieve of 100 meshes to the lineal inch. When
tested neat in the usual manner, it must stand a proof tensile
strain of 475 pounds per square inch when allowed to set one
day in air and six days in water, and 550 pounds when allowed
to set one day in air and 27 days in water. When mixed one
part of cement with three parts of sand, by weight, it shall
stand 150 pounds when allowed to set one day in air and six in
water, and 250 pounds when allowed to set one day in air and
27 in water. Cakes of cement left 24 hours in boiling water
shall show no signs of cracks, blowing or softness. Any brand
of Portland cement which at any time appears inferior or
shows a backward tendency, signs of deterioration or blowing,
will be at once rejected, no matter how good previous tests may
have been, and anv work done with such cement must be at

100 HANDBOOK FOR CEMENT USERS.

once removed and replaced as the engineer may direct, and
without extra allowance to the contractor therefor. Uniform-
ity in quality is essential in this grade of cement, and any
cement which fails to give uniform results under uniform and
approved treatment will be rejected even if it complies with
the specifications in other respects. Evidence of the actual
conduct of cement in sidewalks will also be required in case of
cements not now in use in the city.

10. Brands of Portland cement which have been tested in
the laboratory and are satisfactory for sidewalk construction
are more specifically mentioned under specifications for.
"Cement Sidewalks, Form Q." The brands of cement specified
under "Cement Sidewalks, Form Q," as may be tested and
found to comply with these specifications, can be used pro-
vided the following conditions are fulfilled :

First. All cement shall be shipped here in barrels.

Second. The cement companies shall send with every ship-
ment of cement a sworn statement, showing the length of time
the cement has been stored, the result of seven-day, twenty-
eight-day, and fifty-six-day tests, using one part of cement to
three parts of sand, by weight, in making briquettes. Cement
from one barrel out of each lot of ten barrels of a shipment
shall be tested. The test shall be made by a firm of cement
testers, satisfactory, to the City Civil Engineer, and each barrel
of a shipment shall be stamped with the initials of the cement
tester, the date when cement was tested, and the number of the
barrel.

Third. A chemical analysis of the cement shall be made by
a chemist, satisfactory to the Board of Public Works arid the
City Civil Engineer ; all expense of said analysis shall be borne
by the cement company furnishing the cement, or its agent.

The increase in the requirements made of cement since 1900
is shown by comparing the above specifications with the fol-
lowing adopted for use in Indianapolis in January, 1904 :

1. Inspection. All cements shall be inspected, and those
rejected shall be immediately removed from the work by the
contractor.

2. Storage. On all main sewers, bridges (unless otherwise
ordered) and such branch sewers or other work as the City
Civil Engineer may designate, and shall be provided a suitable
house for storing the cement.

3. Protection. Accepted cement, if not used immediately,
must be thoroughly protected from the weather, and never
placed on the ground without proper blockings, and may be re-
inspected at any time.

4. Failure. The failure of a shipment of cement on any

SPECIFICATIONS FOR CEMENT. 101

work to meet these requirements may prohibit further use of
the same brand on that work.

The acceptance of a cement to be used shall rest with the
Board of Public Works and the City Civil Engineer, and will
be based on the following requirements :

NATURAL CEMENT. By natural cement is meant one
made by calcining natural rock at a heat below incipient fusion
and grinding the product to powder.

Weight. Each bag of natural hydraulic cement must con-
tain 150 Ibs. net ; each barrel 300 Ibs. net.

5. Specific Gravity and Fineness. The cement shall have a
specific gravity of not less than 2.9.

Ninety-five (95) per cent, by weight must pass through a
sieve made of No. 35 wire, Stubbs gauge, 2,500 openings to the
square inch.

Eighty (80) per cent, by weight must pass through a sieve
made of No. 40 wire, Stubbs gauge, 10,000 openings to the
square inch.

0. Constancy of Volume. Round pats of neat cement, about
three (3) inches in diameter, one-half (%) inch thick at the
center and tapering to a feather's edge, mixed in the same man-
ner as the neat cement briquettes on a glass plate, shall not
show any signs of warping or cracking after twenty-eignt (28)
days in either air or water.

7. Time of Setting. The cement shall get its initial set in
not less than thirty (30) minutes. This being determined by
means of the Vicat needle, from pastes of neat cement of nor-
mal consistency, the temperature being between 60 and 70
degrees F.

8. Tensile Strength. Briquettes, one (1) square inch in
cross section, shall develop the following ultimate tensile
strength :

Ages. Strength.

24 hours ( in water after hard set ) 90 pounds

7 days (1 in air, 6 in water) 150 pounds

28 days (1 day in air, 27 in water) 250 pounds

7 days (1 day in air, 6 in water), 1 cement, 2 stan-
dard sand 120 pounds

28 days (1 day in air, 27 in water), 1 cement, 2 stan-
dard sand 175 pounds

PORTLAND CEMENT. The cement shall be a true Port-
land cement, made by calcining a proper mixture of calcareous
and clayey earths, and if desired a certified statement shall be
furnished of the chemical composition of the cement, and the
raw materials from which it is manufactured. It shall be free
from lumps, dry and finely ground.

102 HANDBOOK FOR CEMENT USERS.

Weight. Each barrel must at least weigh 400 pounds gross
and be properly lined so as to be effectually sealed from
dampness.

Specific Gravity and Fineness. The cement shall have spe-
cific gravity of not less than 3.1.

Ninety-eight (98) per cent, by weight must pass through a
sieve made of No. 35 wire, Stubbs gauge, 2,500 openings to the
square inch.

Ninety per cent, by weight must pass through a sieve made
of No. 40 wire, Stubbs gauge, 10,000 openings to the square inch.

Constancy of Volume. Round pats of neat cement about-
three inches in diameter, one-half inch thick at the center and
taperjng to a feather's edge, mixed in the same manner as the
neat cement briquettes and placed on a glass plate, shall not
show any signs of warping or cracking after twenty-eight days
in air or water, or when placed six hours in boiling water.

Time of Set. The cement shall get its initial set in not less
than thirty minutes, and its final set in not less than fifty min-
utes nor more than ten hours. The test being made in the
same way as for the natural cement.

Tensile Strength. Briquettes one square inch in cross sec-
tion shall develop the following ultimate tensile strength.

Ages. Strength.

24 hours (in air) 100 pounds

7 days (1 in air, 6 in water) 400 pounds

28 days (1 in air, 27 in water) ,. . . .575 pounds

7 days (1 in air, 6 in water), 1 of cement, 3 of stan-
dard sand 120 pounds

28 days (1 in air, 27 in water), 1 of cement, 3 of

standard sand 200 pounds

Sulphuric Acid and Magnesia. It shall contain not more
than one and three-quarters per cent, of anhydrous sulphuric
acid (SO 3 ) nor more than 3.5 per cent, of magnesia.

PUZZOLAN. By puzzolan cement is meant one made by
grinding together without subsequent calcination granulated
blast furnace slag with slaked lime.

Weight. The average weight per barrel shall not be less than
330 pounds net, four sacks shall contain one barrel of cement.

Specific Gravity and Fineness. The cement shall have a spe-
cific gravity not less than 2.7.

Ninety-seven per cent, by weight must pass through a sieve
made of No. 40 wire, Stubbs gauge, having 10,000 openings to
the square inch.

Constancy of Volume. Round pats of neat cement about
three inches in diameter, one inch thick at the center and taper-
ing to a feather's edge, mixed in the same manner as the neat

SPECIFICATIONS FOR CEMENT. 103

cement briquettes, and placed on a glass plate, shall not show
any signs of warping or cracking after 28 days in water.

Time of Setting. The cement shall not acquire its initial set
in less than 45 minutes, and shall acquire its final set in 10
hours. The test made in same way as for natural cement.

Tensile Strength. Briquettes one square inch in cross sec-
tion shall develop the following tensile strength:

Ages. Strength.

7 days (1 in air, 6 in water) 350 pounds

28 days (1 in air, 27 in water) 500 pounds

7 days (1 in air, 6 in water), 1 cement, 3 standard

sand 130 pounds

28 days (1 in air, 27 in water), 1 cement, 3 stan-
dard sand 220 pounds

If a sample of cement submitted for test shows higher test
than those given above, the average of tests on subsequent ship-
ments must come up to those found with the sample.

Brands of Portland cement which have been tested in the
laboratory of the City Civil Engineer and found to comply with
these specifications can be used, provided the following condi-
tions are fulfilled :

First. All cement shall be shipped in strong paper bags or
barrels.

Second. With each shipment of cement a certificate of tests
made at the mill and the time that the cement has been stored
shall be submitted.

Third. Contractors must submit the cement and afford every
facility for inspection and testing at least fourteen (14) days
before desiring to use it. The engineer in charge of the testing
laboratory shall be notified at once on the receipt of the ship-
ment of cement.

Fourth. Any cement without the stamp of the engineer in
charge of the laboratory, the maker's name, and the brand on
the barrel or package, will be rejected without test.

Additional Requirements. Should there be discovered at any
time, any characteristics in any cement furnished for the work
that would be objectionable in that work, the further use of
cement of the same brand on all work of that class will be pro-
hibited regardless of the fact that it has successfully withstood
the tests hereinbefore specified.

All cement shall meet such additional requirements as to the
"chemical tests" as the City Civil Engineer may determine.
The requirements for set may be modified where the conditions
are such as to make it advisable.

CEMENT SPECIFICATIONS FOR BRIDGE AT HARTFORD,, CONN.

The following specifications and method of sampling were

104 HANDBOOK FOR CEMENT USERS.

adopted by Edwin D. Graves for a bridge at Hartford, Conn.,
erected by the Connecticut River Bridge and Highway District
Commission in 1904, in which about 100,000 barrels of Port-
land cement were used:

All cement shall be pure American Portland. All cement
shall be dry and free from lumps, well seasoned and free from
slag or other waste products, such as ground limestone or sand.
Manufacturers must guarantee that all cement has been sea-
soned or subjected to aeration at least thirty days before leav-
ing the works. Only high grade American Portland cements of
established reputation, which have been made by the same mill
and process and used successfully under similar conditions to
to those of the proposed work, will be considered, and the de-
cision of the engineer shall be final. The contractor shall fur-
nish the engineer with all the information which he may re-
quire in regard to the record or history of the cement which
he proposes to use. It is desirable that no change in the brand
or quality of cement' be made throughout the work, and con-
siderable preference will be given to that cement whose makers
can guarantee to supply regularly and on time the entire quan-
tity required.

Tests, in general, are to be in accordance with the rules of
the American Society of Civil Engineers, except where other-
wise noted or required by the engineer.

All cement is to be furnished either in first-class barrels or
duck bags, and each package must be perfect, and have the
name of the manufacturer clearly marked upon it.

The contractor must keep on hand in the storehouse at the
work a sufficient supply, in the original packages, to allow a
thirty day test of each lot or consignment of cement before any
of it will be allowed to be used in the work. The cement must be
stored in tiers in a suitable dry storehouse, at least one foot
above the ground, so that every bag or barrel is accessible for
sampling and marking. Each lot or consignment received
must be piled by itself and its date of receipt plainly indicated.
In general, samples shall be drawn from one barrel in 25 or
one bag in 100, but the engineer reserves the right to sample
any or all packages received, and to order a retest at any time.

No cement can be used in the work until it has been accepted
by the engineer, and each package, after acceptance, must bear
an acceptance tag or label, to be affixed by the engineer to each
lot which has satisfactorily passed all the tests which he
desires.

Any cement which has been rejected shall be immediately
removed from the storehouse and from the vicinitv of the work.

SPECIFICATIONS FOR CEMENT. 105

As the accepted cement is removed from the storehouse for
use in the work, the tags or labels must be removed or destroyed
by the engineer.

Each barrel of cement must weigh at least 375 pounds net,
and will be figured as four cubic feet of cement, loose measure.
Each bag is figured to contain one fourth of a barrel, both in
weight and measure.

The proportion of lime to silica shall be about three to one.
Sulphuric acid, less than 1,75 per cent. Magnesia, less than
3 per cent.

Fineness shall be tested by sieves of best standard make:
No. 100 sieve, 10,000 meshes per square inch. No. 200 sieve,
40,000 meshes per square inch. Ninety -five per cent., by
weight must pass a No. 200 sieve. The specific gravity shall be
between 3.10 and 3.20. Initial set not less than one hour.
Final set not over eight hours.

Two cakes of neat cement shall be molded on glass and be
made about 3^2 inches in diameter, %-inch thick at the center,
drawn down to a sharp edge at the circumference. One cake
shall be immersed in cold water, after having set hard, and
then examined from day to day for a period of seven days, in
order to detect surface cracking and warping. The other cake,
after having set hard, shall be immersed in water at 70 degrees
F., supported on a rack above the bottom of the receptacle and
the water gradually raised to the boiling point and maintained
at this temperature for 24 hours. Examination of the cake at
the end of that time must show no signs of checking, cracking
or distorting. The surface color of these cakes, when left in the
air until they are set hard, and after immersion in both hot
and cold water, must be uniform throughout, of a bluish-gray,
and free from light yellowish blotches.

Should the sample fail to pass the hot water test, the engi-
neer reserves the right to reject the lot or to order a retest, or
to subject the sample to chemical analysis in order to deter-
mine whether said failure to pass the hot water test was oc-
casioned by free lime or other deleterious conditions. The en-
gineer may withhold his approval until the result of the twenty-
eight day test of the cake in cold water can be observed, or he
may order a new boiling test from new samples drawn from the
same lot but from different packages. If the twenty-eight day
cold water test or the second boiling test is unsatisfactory, the
lot must be rejected.

Neat briquettes must stand a minimum tensile strain per
square inch : 24 hours in air, 200 pounds ; 24 hours in air and 6
days in water, 500 pounds ; 24 hours in air and 27 days in wa-
ter, 650 pounds.

106 HANDBOOK FOR CEMENT USERS.

Sand mortar briquettes, three parts sand (standard crushed
quartz) to one part neat cement, must stand a minimum ten-
sile strain per square inch without breaking : 1 day in air and
6 days in water, 175 pounds ; 1 day in air and 27 days in water,
275 pounds.

The standard quartz sand shall pass a standard sieve of 20
meshes per lineal inch, 400 meshes per square inch, and be all
retained upon a standard sieve with 30 meshes per lineal inch
or 900 meshes per square inch.

The tensile strength of both neat and sand briquettes shall,
show a satisfactory increase of strength up to periods of one
year. The contractor shall, if required, furnish previously ob-
tained evidences of the strength of the cement at periods of
three, six, nine and twelve months.

When making briquettes, weH dried cement and sand will
be used. Neat cement will be mixed with 20 per cent, of water
by weight; three to one sand and cement mixture, with 12%
per cent, of water by weight.

Sampling is thoroughly and systematically done, and one of
the most notable features of this division of the work lies in
the way in which the samples are used. On the arrival of a
car containing 600 bags or thereabouts, a sample is taken from
every 100 bags as they are being taken to the storehouse, and
these are mixed to form the sample by which that car will be
judged for acceptance or rejection. The tests made on this
sample are embodied in what is called the "acceptance" cement
report, and they include the fineness, soundness, setting time,
tensile strength neat and sand seven days and twenty-eight
days. Four such car samples are subsequently taken and
mixed to furnish the data for the "mixed sample" cement re-
port, in which the features already determined are entered by
their average, and in addition briquettes are made so that data
will be furnished for the three months, six months, and one
year reports. It is believed that the chief engineer has by this
method the fullest knowledge of the character of the cement
which is offered to him, and of that which has gone into his
work that it is possible to have of it, and at a very reasonable
cost. Five-inch concrete cubes are also made from the mixer,
and these are laid away for testing at long periods. Mr. Graves
discovered that he secures better results by making a prism
of such concrete several feet long and having the cubes sawed
out of it by the marble cutter.

A modification of the procedure of sampling has later been
introduced to further facilitate the direct transmission of the
cement to the concrete mixer without passing through the store-
house, and this may be adopted for all of the open season. It

SPECIFICATIONS FOR CEMENT. 10T

consists in sampling certain bins at the cement mill by means of
numerous samples, and locking and sealing these bins until the
samples have been through the regular series of tests at the
laboratory at the bridge site. Cars are loaded only from the
accepted bins, and the cement is sent forward for transship-
ment at Jersey City, where another representative of the lab-
oratory certifies to the proper transshipment and sends for-
ward to the Hartford office all information about the partic-
ular lot of cement on the barge. Complicated as this may seem,
the system and conditions are such that the engineer of this
great work can congratulate himself on having cement in-
spected at a cost which is very reasonable.

CEMENT IN SEA WATER.

The following specification for cement used in sea-water is
taken from those for Wallabout Improvement, Brooklyn, N. Y. :

All the cement to be furnished under this contract must be
of the class of such material known as high-grade Portland
cement, free from lumps, dry and finely ground, and unless as
otherwise specified must be of one or more of the following
brands (three German brands named) . Cement of other brands
may be furnished provided the contractor submits proof satis-
factory to the engineer that it has been used in making large
masses of concrete, which have been exposed to the action of
sea-water for at least two years previous to the date of this
contract, and that such concrete now shows no signs of de-
terioration which might be imputed to defective qualities in
the cement.

All the cement shall be composed of lime, silica and alumina
in their proper forms and proportions, be as free as possible
from all other substances and contain no adulterant in in-
jurious proportions. The ratio of the weight of silica and
alumina to the weight of the lime in the cement shall not be
less than 45 to 100. The cement shall not contain more than
3 per cent, of magnesia nor more than 1 per cent, of sulphuric
acid.

The cement shall not have a lower specific gravity than 3.10.

All the cement shall be of a fineness so that 99 per cent, by
weight shall pass through a No. 50 sieve of No. 35 wire; 90
per cent, shall pass through a No. 100 sieve of No. 40 wire; and
70 per cent, shall pass through a No. 200 sieve of No. 45 wire,
Stubbs' gauge.

The cement must not take its initial set in less than 30 min-
utes after mixing. It shall take its hard set in not less than
3 hours, and in not more than 8 hours.

The cement will be said to have attained its initial and its

108

HANDBOOK FOR CEMENT USERS.

hard set when it bears without indentation, respectively, a wire
1-12 inch in diameter loaded to weigh 1-4 pound, and a wire of
1-24 inch in diameter loaded to weigh 1 pound, it having been
previously mixed neat with about 25 per cent, of its weight of
water and worked for from 1 to 3 minutes into a stiff plastic
paste.

All the cement shall be capable of developing a tensile
strength under various conditions as follows :

Age.

Tensile
Strength

Mixed neat with about 25 per
cent, of water by weight and

'24 hours, in water after hard set
7 days 1 in air 6 in water 60

150
400

worked to stiff plastic paste.

28 days, 1 in air 27 in water 70.

600

Mixed with 3 parts sand by
weight and 12 percent, water
to stiff plastic paste.

7 days, 1 in air 6 in water 70
28 days, 1 in air 27 in water 70

150
240

To determine the tensile strength four briquettes of the
cement under each of the above conditions will be broken in a
Riehle or Fairbanks or other testing machine satisfactory to
the engineer.

The sand to be used in making briquettes will be clean, dry,
crushed quartz, trap-rock or granite, passing a No. 20 sieve of
No. 28 wire and caught on a No. 40 sieve of No. 31 wire, Stubbs'
gauge. The briquettes will be of the form recommended by the
American Society of Civil Engineers.

All cement must be sound in every respect and show no indi-
cations of distortion, change of volume or blowing when sub-
jected in the form of pats to exposure in air and fresh and sea
water of temperature from 60 degrees to 212 degrees, as fol-
lows: The pats will be made of neat, unsifted cement, mixed
with fresh water to the same consistency as before stated for
briquettes, and will be about 3 inches in diameter, having a
thickness at the center of about % inch, tapering to about %
inch at the edges. They will be moulded on plates of glass and
kept thereon during examination, (a) One or more of these
pats will, when set hard, be placed in fresh water of tempera-
ture between 60 degrees and 70 degrees for from 1 to 28 days,
(b) One or more of these pats will be allowed to set in moist
air at a temperature of about 200 degrees for about 3 hours.
It will then be placed and kept in boiling water for a period of
from 6 to 24 hours, (c) One or more of these pats will be
allowed to set in moist air at a temperature of about 100 de-
grees for 3 hours; it will then be placed and kept in water of
temperature of 110 degrees to 115 degrees for a period of from

SPECIFICATIONS FOR CEMENT. 109

24 to 48 hours, (d) One or more of these pats may be sub-
jected to any or all of the above indicated tests (a, b and c),
using sea water instead of fresh water, (e) One pat will be
kept in the air for 28 days and its color observed, which shall
be uniform throughout, of a bluish gray, and free from yellow
blotches. A failure to pass test (b) will not necessaril/ cause*
the rejection of the cement, provided it passes the other tests
for soundness as noted in (a, c, d and e) and is satisfactory
in other respects to the engineers.

All the above tests may be modified and other tests in addi-
tion thereto or in substitution therefor required at the discre-
tion of the engineer to practically determine the fitness of the
cement for its intended use.

The contractor pays the cost of tests of cement which are to
be made by the engineer of the work or by one or more of three
testing laboratories mentioned.

As many tests as desired by the engineer must be made for
composition and specific gravity and one sample shall be tested
for each 100 barrels for fineness, set, tensile strength and
soundness.

All the cement must be furnished in the original package in
strong, substantial barrels, which shall be plainly marked with
the brand or mark of the maker of the cement. Each barrel
must be properly lined with paper or other material so as to
effectually protect the cement from dampness. Any cement dam-
aged by water to such an extent that the damage can be ascer-
tained from the outside will be rejected in toto and the barrels
unopened. Barrels containing a large proportion of lumps will
also be rejected. Broken barrels of cement, if otherwise satis-
factory, will be counted as half-barrels.

The engineer makes the tests upon such proportions of the
whole amount of cement as he sees fit and his decision is final.
He can refuse to accept cement without test and without giv-
ing his reasons.

MUNICIPAL PUBLIC WORKS.

There are one or two interesting points in the following from
the specifications for the Pennsylvania Avenue Subway, Phil-
adelphia.

All the brick work of the sewers except that in the well-holes
was laid in natural hydraulic cement mortar. In the well-
holes Portland cement was specified. In all cases the propor-
tions were 1 of cement to 2 of sand. All concrete used was
composed of 1 part natural hydraulic cement, 2 parts sand and
4 parts of stone or furnace slag.

Briquettes 1 square inch in section made from the natural

110 HANDBOOK FOR CEMENT USERS.

hydraulic cement mortar in the mixing box on the work were
required to develop tensile strength of 40 pounds after 1 day
in air and 6 days in water. Portland cement mortar under
like conditions must show 150 pounds tensile strength.

The other requirements of natural hydraulic cement were as
follows: Weight shall not be less than 112 pounds per im-
perial bushel; residue on No. 50 sieve not over 4 per cent, by
weight, on a No. 100 sieve 25 per cent., on a Xo. 200 sieve 50
per cent. Pats of cement % inch thick, 60 degrees to 70 de-
grees F., shall develop initial set in not less than 10 minutes
and hard set in not less than 30 minutes, the amount of water
being just sufficient to form a stiff plastic paste. The tensile
strength required was 75 pounds in 24 hours, in water after
hard set; 150 pounds, 1 day in air and 6 days in water: 250
pounds, 1 day in air and 27 days in water. Mortar of 1 cement
to 1 of standard quartz sand must show 75 pounds tensile
strength in 7 days.

For municipal work the city of Philadelphia has the strong-
est specifications for cement. The city has a complete testing
laboratory under the Bureau of Surveys, Department of Pub-
lic Works, and a complete organization for keeping close watch
of the materials in use, and can do so at comparatively slight
expense.

1. Inspection. All cements shall be inspected, and those
rejected shall be immediately removed by the contractor. The
contractor must submit the cement, and afford every facility
for- inspection and testing, at least twelve (12) days before de-
siring to use it. The engineer in charge of testing laboratory
shall be notified at once upon the receipt of each shipment of
cement on the work.

-. Packages. No cement will be inspected or allowed to be
used unless delivered in suitable packages properly branded.

3. Storage. On all main sewers, bridges (unless otherwise
ordered), and such branch sewers or other work as the chief
engineer may designate, shall be provided a suitable house for
storing the cement.

4. Protection. Accepted cement, if not used immediately,
must be thoroughly protected from the weather, and never
placed on the ground without proper blockings, and may be
re-inspected at any time.

5. Failure. The failure of a shipment of cement on any
work to meet these requirements may prohibit further use of
the same brand on that work.

The acceptance of a cement to be used shall rest with the
chief engineer, and will be based on the following requirements :

SPECIFICATIONS FOR CEMENT. Ill

Xatural Cement.

6. Specific Gravity and Fineness. Natural cement shall
have a specific gravity of not less than 2.9, and shall leave, by
weight, a residue of not more than two (2) per cent, on a Xo.
50 sieve, fifteen (15) per cent, on a Xo. 100 sieve, and thirty
(30) per cent, on a Xo. 200 sieve. The sieves being of brass wire
cloth, having approximately 2.400. 10,200 and 35,700 meshes
per square inch; the diameter of the wire being .0090, .0045
and .0020 of an inch, respectively.

7. Constancy of Volume. Pats of neat cement one-half
inch thick with thin edges, immersed in water after "hard" set
shall show no signs of "checking" or disintegration. Similar
pats .in air shall show no signs of blotching, checking, or disin-
tegration.

8. Time of Setting. It shall develop "initial" set in not less
than ten (10) minutes, or "hard" set in less than thirty (30)
minutes. This being determined by means of the Yicat needle
from pastes of neat cement of normal consistency, the tempera-
ture being between 60 degrees and 70 degrees F.

9. Tensile Strength. Briquettes, one (1) square inch in cross
section, shall develop the following ultimate tensile strengths:

Age. Strength.

24 hours (in water after "hard" set) 100 Ibs.

7 days ( 1 day in air, 6 days in water) 200 Ibs.

28 days ( I day in air, 27 days in water) 300 Ibs.

7 days (1 day in air, 6 days in water) 1 part of

cement to 2 parts of standard quartz sand. .120 Ibs.
28 days (1 day in air, 27 days in water) 1 part of

cement to 2 parts of standard quartz sand. .200 Ibs.

Portland Cement.

10. Specific Gravity and Fineness. Portland cement shall
have a specific gravity of not less than 3.1. and shall leave, by
weight, a residue of not more than one (1) per cent, on a Xo.
50 sieve, ten (10) per cent, on a Xo. 100 sieve, and twenty -five

per cent, on a Xo. 200 sieve. The sieves -being the same as
previously described.

11. Constancy of Volume. Pats of neat cement one-half
inch thick with thin edges, immersed in water after "hard"
iall show no signs of "checking" or disintegration. Sim-
ilar pats in air shall show no signs of blotching, checking or
disintegration.

12. Time of Setting. It shall require at least twenty (20)
minutes to develop "initial" set under the same conditions as
specified for natural cement.

13. Tensile Strength. Briquettes of cement one (1) inch
square in cross section, shall develop the following ultimate
tensile strengths :

112 HANDBOOK FOR CEMENT USERS.

Age. Strength.

24 hours (in water after "hard" set) 175 Ibs.

7 days ( 1 day in air, 6 days in water ) 500 Ibs.

28 days ( 1 day in air, 27 days in water) 600 Ibs.

7 days ( 1 day in air, 6 days in water ) 1 part of

cement to 3 parts of standard quartz sand. .170 Ibs.
28 days ( 1 day in air, 27 days in water ) 1 part of

cement to 3 parts of standard quartz sand . . 240 Ibs.

14. Sulphuric Acid. It shall not contain more than one
and three-quarters (1%) per cent, of anhydrous sulphuric
acid (SO,).

. 15. Additional Requirements. All cements shall meet such
additional requirements as to "hot water/ 7 "set," and "chem-
ical," tests, as the chief engineer may determine. The require-
ments for "set" may be modified where the conditions are such
as to make it advisable.

The specifications for cement of the Department of Public
Works, Buffalo, N. Y., vary somewhat from those at Philadel-
phia. Kef erring to the paragraphs in the Philadelphia speci-
fications the differences are as follows :

Paragraphs 1 to 5 omitted.

6. Fineness of natural cement 85 per cent, on No. 50 sieve.

7. Cement shall be without free lime, and pats made of neat
cement shall show no cracking when immersed in water imme-
diately 'after set and left for 7 days, nor when subjected to hot
test for 24 hours.

8. Initial set in not less than 10 minutes, Gillmore needles.

9. Tensile strength: Neat, 1 day, 60 pounds; 7 days, 100
pounds; cement 1, sand 2, 7 days, 30 pounds; 28 days, 70
pounds.

10. Fineness of Portland cement 90 per cent, on No. 100
sieve.

11. Same as 7 above.

12. Initial set of Portland cement in not less than 30 min-
utes; final set in not less than 3 hours nor more than 8 hours.

13. Tensile strength : Neat, 1 day, 125 pounds ; 7 days, 300
pounds; cement 1, sand 3, 7 days, 90 pounds; 28 days, 150
pounds.

14. Sulphuric acid requirements omitted. Portland cement
shall not contain more than 3 per cent, by weight of magnesia.

15. Tests shall be made as directed by the engineer in gen-
eral accordance with the American Society of Civil Engineers
standards.

The following differences from the Philadelphia specifica-
tions are noted in the specifications of the City Engineer's
office, Baltimore, Md. :

SPECIFICATIONS FOR CEMENT. 113

Paragraphs 1, 3, 4 and 5 are omitted.

6. Ninety-five per cent, of natural cement must pass a No.
50 sieve.

7. Cakes or pats of neat cement must show no indication of
cracking, checking or warping, when exposed in air and water
at normal temperature.

9. Tensile strength : Natural cement, 1 day, 75 pounds ; 7
days, 150 pounds; 28 days, 225 pounds; 1 cement, 2 sand, 7
days, 80 pounds ; 28 -days, 140 pounds.

10. Ninety-eight per cent, of Portland cement must pass a
No. 50 sieve.

11. Same as 7 above.

12. Initial set shall not develop in less than 30 minutes in
slow-setting, and 10 minutes in quick-setting Portland cement.

13. Tensile strength : Portland cement, neat, 1 day, 125
pounds; 7 days, 400 pounds; 28 days, 500 pounds; 1 cement, 3
sand, 7 days, 125 pounds ; 28 days, 200 pounds.

14. Omitted.

15. Each bag of natural hydraulic cement must contain 150
pounds net; each barrel 300 pounds. Each barrel of Portland
cement must weigh 400 pounds gross, and be properly lined
so as to be effectually sealed from dampness.

The specifications in use by the Bureau of Engineering, Pitts-
burg, Pa., were revised in 1901, and the following is their
present form:

All cement required on the work shall be delivered at a ware-
house within the limits of the city, and the director notified
of each delivery, at least two weeks before it will be needed in,
the work.

Cement shall be so stored, in a dry place thoroughly pro-
tected from rain and dampness, that each shipment is piled
to itself and at all times readily accessible for inspection and
tests.

Cement will be accepted from reliable manufacturers of well-
established reputation only, and the cement will not be tested
or permitted to be used unless delivered in original packages
properly labeled. .

Tests of the cement will, unless otherwise specified, be made
at a temperature of from 60 to 70 degrees Fahrenheit.

Samples for test may be taken from every package in each
shipment of cement, and unless they meet the requirements
herein specified, the whole shipment from which the samples
were taken will be rejected.

The sieves used for testing cement for fineness and for gaug-
ing the sand to be used in making briquettes for sand tests shall
be as follows :

114 HANDBOOK FOR CEMENT USERS.

No. 20 sieve shall have 400 meshes to the square inch, and
shall be made of wire cloth, No. 28 wire Stubbs' wire gauge. -

No. 30 sieve shall have 900 meshes to the square inch and
shall be made of wire cloth, No. 31 wire Stubbs' gauge.

No. 50 sieve shall have 2,500 meshes to the square inch and
shall be made of wire cloth, No. 35 wire Stubbs' gauge.

No. 100 sieve shall have 10,000 meshes to the square inch, and
shall be made of wire cloth, No. 40 wire Stubbs' gauge.

Briquettes for testing strength of cement will be made both
of neat cement and sand in the proportions hereinafter speci-
fied, with only enough water added to thoroughly moisten the
mixture and make it coherent.

After being thoroughly mixed on glass plate the mortar shall
be firmly pressed into the molds by hand, and the briquettes
so formed placed upon a glass plate and kept there until put in
water.

The sand used in preparing briquettes shall be, unless other-
wise specified, clean, sharp, crushed quartz, crushed so that
the whole of it will pass through a No. 20 sieve and be retained
on a No. 30 sieve.

Kound pats of neat cement, about three (3) inches in diam-
eter, one-half an inch thick at the center and tapering to a
feather's edge, mixed in the same manner as the neat cement
briquettes and placed on a glass plate, shall not show any
signs of warping or cracking after twenty-eight (28) days in
either air or water.

Any cement which shows signs of swelling, after being mixed,
will be rejected.

Portland cement shall be ground to such a degree of fineness
that not less than 98 per cent, by weight shall pass a No. 50
sieve, and not less than 90 per cent, by weight pass a No. 100
sieve.

Natural cement shall be ground to such degree of fineness
that not less than 88 per cent, by weight will pass a No. 50
sieve, and not less than 77 per cent, by weight pass a No.
100 sieve.

The tensile strength ^of cement will be determined from an
average of not less than five briquettes, made of samples taken
from the same shipment of cement.

The average ultimate tensile strength of briquettes made of
neat Portland cement shall be, after being kept in air one day
and in water six days, not less than 400 pounds, and after
being kept in air one day and in water 27 days, not less than
550 pounds.

The average ultimate tensile strength of briquettes made of
one part by weight of Portland cement and three parts of sand

SPECIFICATIONS FOR CEMENT. 115

shall be, after being kept in air one day and in water six days,
not less than 120 pounds, and after being kept in air one day
and in water 27 days, not less than 175 pounds.

The average ultimate tensile strength of briquettes made of
neat natural cement shall be, after being kept in air one day
and in water six days, not less than 110 pounds, and after
being kept in air one day and in water 27 days, not less than
ISO pounds.

The average ultimate tensile strength of briquettes made of
one part by weight of Portland cement and three parts of sand
shall be, after being kept in air one day and in water six days,
not less than 40 pounds, and after being kept in air one day
and in water 27 days, not less than 175 pounds.

In addition to the tests above specified, all cement furnished
for the work shall be subject to such other tests as may be
necessary to determine whether the cement possesses the proper
qualities for the particular work for which it is designated.

Should there be discovered at any time, any characteristics
in any cement furnished for the work that would be objection-
able in that work, the further use of cement of the same brand
on all work of that class will be prohibited, regardless of the
fact that it has successfully withstood the tests hereinbefore
specified.

The above specifications have been changed from those used
the previous year as follows: Neat Portland cement tensile
strength raised from 375 pounds at seven days and from 510
at 28 days ; 3 to 1 sand and Portland cement lowered from 190
pounds at 28 days ; neat natural hydraulic cement, 24-hour test
omitted; 2 to 1 sand and natural hydraulic cement lowered
from 50 pounds at 7 days.

The city of Detroit does not require so much and may secure
cement under its specifications which, while passing the tests
required, is deficient in a marked degree in other respects.
The specifications in use are as follows :

Cement to be put up in cloth or paper sacks, original pack-
ages, each sack to be branded- with the name of the manufac-
turer or manufacturers, and to contain 95 pounds net of Port-
land cement, or 132 1 / pounds net of natural cement, and to be
delivered in such quantities and at such times as the Board of
Public Works may direct, unloaded in a warehouse which shall
be located on the railroad, between 12th and Riopelle streets,
south of Michigan avenue, or Gratiot avenue, in the city of De-
troit, and no extra charge shall be made for storage or de-
livery.

116 HANDBOOK FOR CEMENT USERS.

A man satisfactory to the Board of Public Works shall be
furnished by the contractor to assist in loading.

The sacks to be the property of the city of Detroit, and each
bidder shall state in connection with his bid, the price per cloth
sack he will pay for each empty sack delivered at the ware-
house aforesaid.

The Board of Public Works reserves the right to reject any
cement considered by said Board not equal in quality to the
standard above mentioned.

Portland Cement shall be of American manufacture, and
shall stand a test of 130 pounds per square inch tensile strain,
when made into briquettes and exposed in air until final set
and the balance of 24 hours immersed in water. One day in
air and 6 days in water shall show a tensile strength of 380
pounds; 1 day in air and 27 in water shall show a tensile
weight of one of cement to two of sand, in 7 days it shall stand
a tensile strain of 146 pounds, and in 28 days a strain of 216
strength of 520 pounds, and when mixed in proportion by
pounds.

In fineness, 95 per cent, shall pass through a No. 50 sieve.

Natural Cement shall be of American manufacture, and shall
stand a test of sixty (60) pounds per square inch tensile strain
when made into briquettes, exposed 1 hour in air and immersed
for twenty-three (23) hours in water; and when mixed in pro-
portions by weight of 1 of cement to 2 of sand, and exposed 1
day in air and 6 days in water, it shall stand a tensile strain
of at least fifty (50) pounds per square inch; and in fineness
not less than 90 per cent, must pass through a sieve of twenty-
five hundred (2,500) meshes to the square inch.

INSUFFICIENT SPECIFICATIONS.

The following cement specifications for 1901, from a city of
90,000 inhabitants, are presented as an unsatisfactory set,
which will permit the use of poor cement of both kinds unless
arbitrary rejections are made outside of the specifications.

Cement shall be of the best quality of Louisville cement or
of cement equal in all respects thereto, fine ground, quick set-
ting, capable when made into testing blocks of withstanding a
tension of 60 pounds per square inch of section, when mixed
pure and exposed in air 1 hour and 23 hours in water.

The contractor must furnish the cement in strong, perfect
paper sacks to any part of the works, and in such quantities
as the Commissioner of Public Works may direct, and only
upon the written order of said Commissioner. Bids to specify
the price per hundred pounds at which the cement is to be fur-
nished. To be weighed on the public scales.

SPECIFICATIONS FOR CEMENT. 117

The cement used for the curbing and tiling shall be of the
best quality of American or imported Portland cement, capable
of withstanding a tensile strength of 500 pounds to the square
inch when mixed neat and allowed to stand 1 day in air and 6
days in water.

FOR SEWERS.

For sewer work the following are given as examples of prac-
tice:

The Department of Sewers, Reading, Pa., requires :

Composition. Magnesia not over 2~y 2 per cent.; sulphuric
acid not over 2 per cent.

Fineness. Ninety-five per cent, through a No. 100 sieve; 80
per cent, through a No. 200 sieve.

Checking and Cracking. Two cakes of neat cement to be
moulded on glass. One to be immersed in cold water, after
having set hard, and examined from day to day for surface
checking and warping, the other having been set hard to be
immersed in water at 212 degrees F., and allowed to remain in
water of that temperature for 24 to 36 hours. Examination
of the pat at the end of that time for constancy of volume and
checking. Should the pats become contorted or show signs of
warping or cracking the cement will be rejected.

Tensile Strength. Neat, 24 hours, 200 pounds; 7 days, 500
pounds; 28 days, 650 pounds; mortar, 3 to 1, 7 days, 150
pounds; 28 days, 250 pounds.

The City Engineer's office, Peoria, 111., requires :

Natural Hydraulic Cement. All cement shall be what is
commonly known as American natural hydraulic cement, of
quality equal to the best obtainable in the market. It will be
subject to rigid inspection and must be able to stand the fol-
lowing tests : Two cakes 3 inches in diameter and % i nc h thick
with thin edges, will be made. One of these cakes as soon as
set will be placed in water and examined from day to day. If
the cake exhibits checks, cracks or contortions, the cement will
be rejected. The other cake described will be used for setting
and color tests. The time will be noted when the cake has be-
come hard enough to sustain a wire 1-12 inch in diameter loaded
with !/4 pound. When the wire is sustained the cement has
begun to set and this time shall not be less than 30 minutes.
When the cake will sustain a wire 1-24 inch in diameter with 1
pound, the test is complete, and this time must not be less than
1 hour nor more than 3 hours. The cake used for setting test
will be preserved, and when examined from day to day must be
of uniform color, exhibiting no blotches or discolorations. The
cement must be evenly ground and when tested with the follow-

118 HANDBOOK FOR CEMENT USERS.

ing standard sieves must pass at least the following per-
centages :

No. 20 sieve, 100 per cent.; No. 74 sieve, 80 per cent. All
cement for test briquettes, whether to be used neat or with
sand, will be mixed with barely sufficient water to make a stiff
dough or mortar. The sand for cement tests will be of such
fineness that all will pass a sieve of 20 meshes per llineal inch,
and none of it pass a sieve of 30 meshes per lineal inch. It
will be the best quality obtainable of washed river sand. The
required tensile strength per square inch shall be as follows:
Neat cement, 1 day, till set in air, remainder of time in water,,
60 pounds ; 1 day in air, 6 days in water, 100 pounds ; cement 1
part and sand 2 parts, 1 day in air, 6 days in water, 65 pounds.

FOUNDATIONS.

A few samples of specifications for cement for foundations
are given ; first for foundation of standpipe, used by the Water
Works Department, St. Louis, Mo.:

All cement for the work herein specified shall be of the best
quality of American Portland. Cement without the manufac-
turer's brand will be rejected without test. All cement fur-
nished will be subject to inspection and rigorous tests of such
character as the Water Commissioner shall determine, and any
cement which in the opinion of the Water Commissioner is un-
suitable for the work herein specified, will be rejected.

If a sample of the cement shows by chemical analysis more
than 2 per cent, of magnesia (Mg O) or more than V/ 2 per cent,
anhydrous sulphuric acid (SO 3 ) the shipment will be rejected.

To secure uniformity in cement of approved brands, all
cement received on the work shall be subject to tests for check-
ing or cracking and to the following tests for fineness and ten-
sile strength :

All cement shall be fine ground and 85 per cent, shall readily
pass a sieve having 10,000 meshes to the square inch.

All cement shall be capable of withstanding a tensile stress
of 400 pounds per square inch of section when mixed neat, made
into briquettes and exposed 24 hours in air and 6 days in water.

All cement shall be put up in well-made barrels and all short
weight or damaged barrels will be rejected. Samples for test-
ing shall be furnished at such times and in such manner as may
be required. On all barrels of rejected cement inspection marks
will be placed, and the contractor shall in no case allow these
barrels to be used.

In measuring cement for mortar or concrete, the standard
volume of a barrel of cement shall be determined by compar-
ing its net weight with the weight of one cubic foot of thor-
oughly compacted neat cement.

SPECIFICATIONS FOR CEMENT. 119

All cement for use on the works shall be kept under cover
thoroughly protected from moisture, raised from the ground
by blocking or otherwise, and dry until used. The contractor
shall keep in storage a quantity of accepted cement sufficient
to secure the uninterrupted progress of the work.

Accepted cement may be re-inspected at any time and if
found to be damaged or of improper quality will be rejected.
All rejected cement shall be at once removed from the work.
Philadelphia Architects.

PORTLAND CEMENT. Chemical Composition. The cement
must show less than 2 per cent, of sulphuric acid and less than
2y 2 per cent, of magnesia.

Fineness. Ninety per cent, shall pass a No. 70 sieve; 85 to
90 per cent, shall pass a No. 100 sieve ; 68 to 70 per cent, shall
pass a No. 200 sieve.

Checking, Cracking and Color. Three cakes of neat cement
are to be moulded on glass 2 or 3 inches in diameter and about
y 2 inch thick at the center, the edges being very thin. These
cakes are to be made from a mixture of the cement and water
to the consistency of a stiff plastic mortar. Cake No. 1 is to
be left in the air for a determination of color. The color must
be uniform throughout, of a bluish or greenish gray for Port-
land, and the cake must be free from yellowish blotches. The
cake must show no signs of cracking or lis^ortion after being
kept indefinitely. Cake No. 2 is to be put n old wi ter as soon
as set stiff enough for the purpose, and to remain there 2 or 3
days, when it will be put in water at 200 degrees F., and kept
there for 24 or 48 hours. At the end of this time the cake should
show no signs Of cracking, swelling, blowing or distortion.
Cake No. 2 when hard enough is to be placed in water and ex-
amined from day to day to ascertain if it becomes contorted,
or if cracks show themselves at the edge.

Tensile Strength. Neat cement, 7 days, 400 to 500 pounds;
28 days, 600 pounds; mortar, 3 to 1, 7 days, 150 pounds; 28
days, 250 pounds.

TWO ENGLISH REQUIREMENTS.

Two requirements in English type specifications for impor-
tant works cover points which have heretofore not required
much attention in this country, but, under the changing condi-
tions in the cement market, may become of importance. One
provides that if the rise in temperature in a sample of cement
mixed with water for the purpose is more than 6 degrees in an
hour after mixing, the cement is not ready for use or testing,
and the other provides for aerating the cement found to be too

120 HANDBOOK FOR CEMENT USERS.

young, by spreading it on a perfectly dry floor in a water-tight
shed near the works, not more than one foot deep, and turning
it over from time to time until tests show that it has prop-
erly aged. The introduction of the rotary kiln in England and
the consequent use of gypsum to temper cement reduces the
latest English practice, where the cements made in this way
are used, to the same basis as American practice.

THE USES OF CEMENT.

The expansion of the field occupied by cement construction
is so great and so rapid that such a chapter as this requires
frequent revision to keep it up to date. Many of the uses to
which cement is put are considered in detail in the following
chapter on Specifications for the Use of Cement. Some others
may be mentioned here as well as some methods of modifying
the quality, characteristics and appearance of cement for vari-
.ous reasons.

The first and most important use of cement is in making
mortar, for brick and stone masonry and concrete. There are
so many variations in materials and proportions that the chap-
ters on Specifications can give but a part of them, those in most
common use, and those chapters contain > perhaps, sufficient de-
tail regarding the proper places to use the various mixtures.
Some consideration of the cost of mortars of various propor-
tions and of concrete may be of value, not as giving exact fig-
ures for such cost, but as giving the principle upon which an
investigation may be made in any particular case. The follow-
ing is from a consideration of some experiments in this line by
L. 0. Sabin, U. S. Assistant Engineer, in Municipal Engineering
Magazine :

INGREDIENTS OF A CUBIC YARD OP CEMENT MORTAR AND OP CON-
CRETE AND THE COST.

1. The character of the ingredients used in making cement
mortar varies so much that it is difficult to accurately deter-
mine the cost of a proposed mortar except by experimenting
with the materials that are to be employed. The weights per
cubic foot of both cement and sand vary greatly according to
the conditions of packing, the moisture, etc. The percentage of
voids in the sand is one of the most important variations affect-
ing the amount of mortar made with certain materials mixed
in given proportions. The consistency of the mortar also has
a marked effect, and different cements show a considerable
variation in the volume of mortar that a given weight will
yield. In any general treatment of the question, then, we
may expect only approximate results, and the discussion here
given must be considered in this light.

122 HANDBOOK FOR CEMENT USERS.

2. The experiments, from which tables 1 and 2 are de-
rived,* were made with a natural sand weighing 100 pounds
to the cubic foot, dry, and having about three-eighths of the
bulk voids. The grains varied in size from 0.01 inch to 0.1
inch in diamaeter, with a few grains outside of these limits.
The consistency of the mortar was such that when struck
with the shovel blade the moisture would glisten on the
smooth surface thus formed. In the experiments the propor-
tions were determined by weight, and the results for pro-
portions by volume w.ere deduced from them. The results for
neat, natural cement mortar and for the natural cement mor-
tars containing more than four parts sand by weight wore
derived by analogy.

EXPLANATION OP TABLES.

3. The first section of table 1 gives the amount of ma-
terial required for Portland cement when the proportions are
stated by weight; the second and third sections refer to pro-
portions by volume of loose sand to packed cement when the
size of the cement barrel is assumed at 3.65 cubic feet and
3.33 cubic feet, respectively. The fourth section gives the
materials required when the proportions are given in terms
of volume of loose sand to loose cement. Likewise, the first
section of table 2 for natural cement refers to proportions by
weight; the second, third and fourth sections, to proportions
by volume of loose sand to packed cement when the cement
weighs 265 pounds, 280 pounds and 300 pounds net per barrel
respectively; while the fifth section refers to proportions of
loose sand to loose cement.

The method of stating proportions by weight is the most
accurate, but when the sand does not approximate the weight
of 100 pounds per cubic foot when shoveled dry into a meas-
ure, the sections of the tables referring to weight proportions
may require a correction, and it may be simpler to use the
sections giving proportions by volume of loose sand to packed
cement. The method of stating proportions by volume of
loose sand to loose cement is to be deprecated, but since it is
occasionally used provision is made for it in the tables.

In using those portions of the tables where the proportions
are stated by volume it should be borne in mind that if the
sand is damp when used it will weigh less per cubic foot;
hence more, by measure, will be required to make a cubic
yard of mortar.

COST OP MORTAR.

4. With the data given in tables 1 and 2 and a knowledge

Annual Report of Chief of Engineers, U. S. A.. 1894, p. 2312.

THE USES OF CEMENT.

123

of unit prices of the materials used in the mortar, one may
estimate the cost of the materials in a given quantity of mor-
tar. The cost of mixing will, of course, depend upon the cost
of labor, the method employed, etc., and may vary from fifty

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124 HANDBOOK FOR CEMENT USERS.

cents to a dollar and fifty cents per cubic yard. If we as-
sume for illustration that natural cement can be delivered on
the mixing platform for $1.10 per barrel of 280 pounds net,
that sand costs 60 cents per cubic yard and the mixing costs
$1.00 per yard of mortar, then we have for the cost of a mortar
composed of one part cement to two parts sand by weight,

3. 46 bbls. cement at $1.10

.72 cu. yd. dry sand at .60

Cost of mixing per cu. yd

Total cost of one cu. yd. of mortar $5.23

5. For approximate results diagrams 1 and 2 give the cost
of the materials used in a cubic yard of mortar for different
prices of cement. In diagram 1 the proportions by weight
only are indicated, since, for Portland, the proportions by
volume of loose sand to packed cement vary so little from
proportions by weight. In diagram 2 the proportions of nat-
ural cement mortars are given by volume of packed cement
(280 pounds net per barrel) and loose sand, as well as by
weight. The diagrams are made upon the assumptions that
the sand is similar to that used in the experiments recorded
in tables 1 and 2, and that the cost of sand is fifty cents per
cubic yard.

Example.

6. To indicate the use of these diagrams let us determine
the cost per cubic yard of mortar containing two parts sand
to one of natural cement by weight when cement costs |1.30
per barrel of 300 pounds net, and sand is thirty cents per
cubic yard. One dollar and thirty cents per barrel of 30
pounds is equivalent to 0.43 cents per pound, and entering dia-
gram 2 with this quantity, we follow the corresponding
abcissa till we reach the line marked 1 to 2 by weight; we
find this to be the ordinate four dollars and fifty cents per
cubic yard. But in the diagram the sand is assumed to cost
fifty cents per cubic yard instead of thirty cents as in the
example, and as .72 cubic yard sand is used (see table}, we
must subtract .72 of twenty cents, or fourteen cents, from
this result, making the materials for the mortar cost $4.36
per cubic yard of mortar. If the proportions were by vol-
ume of packed cement and loose sand the cost of the ma-
terials per cubic yard of mortar would be $3.75 less twenty
times .78, or $3.59.

It is understood that the cost of the materials alone is
given by the diagrams; the cost of mixing the materials must
be added to obtain the total cost.

7. The rules given for determining the proportions of in-

THE USES OF CEMENT.

125

gredients to use in concrete are not all to be commended,
and while this article is concerned chiefly with the quantities
of materials required when the proportions have been de-
cided upon, we may suggest briefly the principle which should
underlie the determination of these proportions.

-d

DIAGRAM N 6 1

From Table N 1.
Portland.

1.60 180 2OO 2.20 2.4O 2 6O L.8O

Price of cement per bbl of 38O pounds net - dollars

3.00

126

HANDBOOK FOR CEMENT USERS.

215

Trie of cement per pound cente
.J85 355 43O 500 37O

640

DIAGRAM N 2
Table N* ^.

Natural

0.60 0.80

1.00

1.20

L4-0

1.60

1.80

Price of cement per bblof 28O pounds net - dollars.

8. Concrete is simply a class of masonry in which the
stones are small and of irregular shape. The strength of the
concrete is largely dependent upon the strength of the mor-
tar ; in fact, this dependence will be much closer than in other
classes of masonry, since it may be stated, as a general rule,

THE USES OF CEMENT. 127

that the larger and more carefully cut are the stone, the less
will the strength of the masonry depend on the strength of
the mortar. In deciding, then, upon the proportions of in-
gredients to use in a given case, the quality of the mortar
should first be considered. If the concrete is to be subjected
to a moderate compressive stress, the mortar may be com-
paratively poor in cement; but if great transverse strength is
required, the mortar must be of sufficient richness; while, if
the concrete is to be impervious, the mortar must possess this
quality as well.

9. In making concrete the general rule should be that
enough mortar be used to just fill the voids in the stone. If
either less or more mortar than this amount be employed the
concrete will in general be weakened thereby. The last state-
ment is subject to one exception. If the mortar becomes
stronger than the stone then an excess of mortar does not
weaken the concrete; this case, however, should never be per-
mitted to occur, the aggregate used should have a strength
at least equal to that required of the concrete. It is a simple
matter then to determine the required amount of mortar for
a given volume of broken stone or aggregate, and the amount
of cement and sand for a given volume of mortar has already
been considered.

10. The bulk or volume of a given mass of broken stone is
not so variable a quantity as the volume of sand. The volume
of the aggregate will vary considerably with the degree of
packing, but the packing is influenced appreciably by the
amount of moisture present. The percentage of voids in the
aggregate may be determined as follows : Obtain the weight
per cubic foot of the broken stone in the condition in which
the percentage of voids is sought. Also obtain the specific
gravity, and hence the weight per cubic foot, of the solid
stone. Then one, less the quotient obtained by dividing the
weight per cubic foot of the broken stone by the weight per
cubic foot of the solid stone will be the proportion of voids
in the former. Another method is to ,611 a vessel of known
capacity with the aggregate to be used, and to pour in a meas-
ured quantity of water until the vessel is entirely filled. , The
volume of water used indicates the necessary quantity of
mortar. In using this method the stone should be moistened
before placing in the vessel to avoid an error from the ab-
sorption of the water used to measure the voids.

11. As to the degree of jarring or packing to which the
stone should be subjected in filling, if the stone is put in
loose, and it is proposed to ram the concrete in place, the
amount of mortar indicated will be somewhat more than the

128 HANDBOOK FOR CEMENT USERS.

required quantity; if the concrete is to be deposited without
ramming (as in submarine construction), the amount of mor-
tar indicated will not be too great. On the other hand, if the
aggregate is shaken down in the vessel to refusal, the voids
obtained will be less than the amount of mortar which should
be used, because it is not possible to obtain a perfect distribu-
tion of mortar in a mass of concrete, such that the concrete
will occupy the same space as did the broken stone when
thoroughly shaken. And again, for perfect concrete, pieces
of stone should be separated one from another by a thin film,
of mortar, and hence the volume of the concrete will be
greater than the volume of the aggregate measured in com-
pact condition without mortar. A deficiency of mortar is
usually more detrimental than an excess. It is, therefore,
safer to measure the voids in the stone when but slightly
jarred and make the amount of mortar correspond to the
voids so obtained.

12. We may say, then, that the rational method of pro-
portioning concrete is to let the duty required of the con-
crete fix the quality of the mortar, and let the quantity be
sufficient to fill the voids in the aggregate. Knowing the per-
centage of voids in the aggregate, and consequently the per-
centage of mortar which should be found in a cubic yard of
the finished concrete, we may obtain the approximate cost per
cubic yard of the latter for a given quality of mortar and
given unit prices.

Thus, suppose we have stone in which the voids are such
that the mortar will amount to 40 per cent, of the finished
concrete, and we wish to have the mortar composed of two
parts sand to one part natural cement, by weight, unit prices
being as follows:

Cement, $1.30 per bbl. of 30> pounds, net
Sand. .30 per cubic yard.

Stone, 1.25 per cubic yard.

As in paragraph 6 we find the ingredients in one cubic yard
of mortar to cost |4.36. Since 40 per cent, of the concrete is
to be mortar, the mortar in one cubic yard of concrete will
cost 40 per cent, of $4.36, or fl.75, and one yard of stone at
f 1.25 will make the total cost of the materials in the concrete
f 3 per cubic yard.

13. Diagram No. 3 may be used to get the approximate
cost of the concrete after having obtained the cost of the mor-
tar from either diagram 1 or 2. Thus, if we enter diagram 3
with cost of mortar $4.36, and follow the abcissa to the diag-
onal line marked 40 per cent., we find this to be on the ordi-
nate $2.75, the cost of the ingredients in a cubic yard of the

Cost of concrete dollars per cu yd.,wKen stone costs l^per cu yd

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130 HANDBOOK FOR CEMENT USERS.

concrete when the stone costs fl per cubic yard. Hence,
|2.75 + $0.25= $3, the approximate cost of the materials in a
cubic yard of the finished concrete as desired. The qualifica-
tion "approximate" is used advisedly, because it is well
known that since the amount of concrete made from given
quantities of ingredients is subject to slight variation from
so many causes, accurate estimates of cost are not possible.

14. The usual method, however, of stating proportions in
concrete is to give the volume of sand and stone to one voK
ume of cement. Thus, one of cement, three of sand and six
of stone, would usually mean one volume of packed cement,
three volumes of loose sand and six volumes of loose broken
stone. When proportions are thus arbitrarily stated, we may
determine, from the tables and diagrams already given, the
amount of water which a given quantity of dry ingredients
will make, and the consequent cost of the mortar per cubic
yard. Then a knowledge of the voids in the broken stone will
permit of a close estimate of the amount of concrete made,
whence the cost of the latter.

For example, suppose it is desired to determine the cost of
materials in a cubic yard of natural cement concrete under
the following conditions:

One bbl. cement containing 280 pounds net at $1 per bbl.

Three bbls. sand weighing 100 pounds per cubic ft. at $0.75 per cu. yd.

Six bbls. loose broken stone having 45 per cent, voids at $1.25 per cu. yd.

1 bbl. cement 3.75 cu. ft. -0.239 cu. yd. cost , $1.000

3 bbls. sand 11.25 cu. ft-. 417 cu. yd. cost 313

6 bbls. stone-22.50 cu. ft .833 cu. yd. cost 1.041

Total cost $2.354

From table 2 we find that it requires 2.03 barrels of cement
to make one cubic yard of one to three mortar; then one bar-
rel of cement would make 0.493 cubic yard. As 45 per cent, of
the stone is voids the amount of solid stone in six barrels of
broken stone would be .833 x .55 = .458 cubic yard. Then the
mortar plus solid stone would be .493 + .458 = .951 cubic yard.
It has been found by experiment that the amount of concrete
made will usually exceed the sum of the mortar and solid
stone by from two to five per cent., hence we may assume in
this case that .98 cubic yard concrete resulted from the above
materials and 2.354 -*- .98 = $2.40, the cost of the material in
one cubic yard of finished concrete. To obtain the actual cost
of concrete in place, the cost of mixing and deposition must
be added.

The following table prepared by Mr. C. E. Fowler shows the
amounts of each material required to make one cubic yard of

THE USES OF CEMENT.

131

Barrels

Cu Yds.

Cement

Sand.

1.77

0.51

1.68

0.49

1.59

0.47

1.48

0.44

1.39

0.42

1.30

0.40

1.30

0.57

1.22

0.54

1.16

0.52

1.09

0.50

1.04

0.48

1.00

0.55

0.96

0.55

0.92

0.51

0.88

0.49

0.83

0.47

Stone
0.4 voids

Stone
0.5 voids.

0.85
0.81
0.95
1.00

1.05
.10
.15
.20

1.04
1.08
0.83

.26
.30
1.00

0.89
0.92
0.97
1.00

1.06
1.11
1.16
1.20

091
0.94
0.67
1.00

1.09
1.13
1.17
1.21

1.03

1.25

Portland cement concrete with various proportions of cement,
sand and stone. It is made by comparison with actual cases
and gives very satisfactory results in practice.

Proportions.

1-2-3

1-2-31

1-2-4

1-2-4*

1-2-5

1-2-5J

1-3-4

1-3-4*

1-3-5

1-3-5J

1-3-6

1-4-6

1-4-6*

1-4-7

1-4-71

1-4-8

The heavy lines are put in the table to aid in selecting those
mixtures in which the voids of the stone are completely filled
and those which are but partly filled.

William B. Fuller's rule for determining the quantities of
ingredients in a cubic yard of concrete for various proportions
is as follows :

The sum of the proportions of cement, sand and stone is taken
and the number 11 is divided by this sum. The result is the
number of barrels of Portland cement required for a cubic
yard of concrete. The proportions are stated in the usual
form, one part of cement to assumed numbers of parts of sand
and stone. The number of barrels of cement multiplied by the
proportion of sand and by 3.8, the number of cubic feet in a
barrel, and the product divided by 27, gives the number of cu-
bic yards of sand required and a similar computation gives the
number of cubic yards of stone.

The results of this formula may be compared with Mr. Fow-
ler's table, above, and will be found in substantial agreement
as to quantity of cement, being usually larger for rich concrete
and less for leaner concrete. It will be noted, also, that the
formula would give the same amount of cement for a 1:2:5
mixture as for a 1 :3 :4. The same may be said regarding the
quantity of sand, except that for the richer concretes the for-
mula reduces the amount of sand. For broken stone the for-

132 HANDBOOK FOR CEMENT USERS.

mula gives results about 8 per cent, less than the table.

A paper on the Theory of Concrete, by George W. Rafter, be-
fore the American Society of Civil Engineers, describes some
experiments made by him. Concrete blocks made part with
mortar equal to 33 per cent, of the stone and part with 40 per
cent, were made, part with the dryest mixture possible, part
with enough water to make the mixture plastic, and part with
an excess of water. Four brands of natural cement and two
brands of American Portland cement were used. In all, 173
blocks of concrete, each one cube foot, were made and crushed.

The blocks made with 40 per cent, of mortar and an excess
of water averaged 2,227 pounds crushing strength per square
inch, with plastic mortar 2,329 pounds, with dry mortar 2,532.
A similar ratio exists in the case of 33 per cent, mortar. The
40 per cent, concrete averaged 4 per cent, stronger than the
33 per cent. This excess of strength was as high as 7 per
cent, with mortar made of one part cement to two parts sand,
and there was no excess with mortar of 1 to 4.

In a paper before the Indiana Engineering Society, Mr. S.
B. Newberry discusses the relations of the proportions of ma-
terials to the strength of concrete, and makes several points
which are in effect as follows: The purpose in combining the
sand, gravel and broken stone is to produce the greatest pos-
sible density, which can be accomplished by adjusting the pro-
portions of the finer material to fill the voids in the coarser
material as completely as possible. The variety of sizes from
smallest to coarsest must be the greatest possible. Screen-
ing is undesirable between these limits unless by separating
and remixing better proportions can be obtained. Voids in
various materials were reported as follows:

Sandusky Bay sand, not screened 32.3 per et.

Kentucky sand 31 per ct.

Gravel 4 -in. to 1-20 in ... ..35.0 per ct.

Gravel passing 1^-in. screen and freed from sand

by a fine screen . . 35 per ct.

Broken stone, l-in..to 2-in., from Marblehead, .. .47 per ct.
Broken stone, 2}-in. and less 48 per ct.

Voids in broken stone can be found by the weight of water
a given volume will contain. Voids in sand are best obtained
by comparing the weight of a given volume with the weight

THE USES OF CEMENT. 133

of a similar volume of the solid rock, as derived from the spe
cific gravity of the sand material.

From a paper by Dyckerhoff before the German Portland
Cement Manufacturers' Association, Mr. Newberry quotes
the following table showing greater strength for less propor-
tion of cement up to the limit of proportion of voids:

Strength under compression
Portland Cement Sand Gravel in Ibs. per sq. in.

1 2 2,125

1 2 3 2,747

1 2 5 2,387

1 5 978

1 3 1,383

135 1,682
1 3 6} 1,515

1 4 1,053

145 1,273

1 4 81 1,204

Mr. W. B. Fuller's rule is quoted with approval, to "mix the
sand and stone or gravel in a definite fixed proportion as de-
termined by experiment for the material in use and add
cement as economy dictates, possibly up to 10 per cent, in
excess of the voids in the combined material." Using the ma-
terials above named, the theoretical proportions of cement,
sand and gravel for the best concrete would be 1, 3.1 and 8.6,.
and for cement, sand and broken stone, 1, 3.1 and 6.5. In
practice the proportion of sand should be increased slightly.
These concretes will give a crushing strength of over 2,000
pounds a square inch after 28 days, and can be increased in
strength to 4,000 or 5,000 pounds by increasing the proportion
of cement. Increasing the proportion of sand at the same
time will make the increase in strength less noticeable. The
mixture 1 cement, 3 sand, 8% gravel is stronger than the mor-
tar without the gravel. Wet concrete is preferred.

The yield of concrete for given quantities of materials,
using gravel with 35 per cent, voids is reported by Dycker-
hoff as follows:

Cement Sand Gravel Concrete

1 2 4 4.4

136 6.65
148 8.85

Were the proper proportion of sand to fill the voids used,
the resulting volume of concrete would be nearer equal to the
volume of gravel.

134 HANDBOOK FOR CEMENT USERS.

Professor W. K. Hatt reported some results of tests with
natural hydraulic cement showing similar increase in
strength for the complete filling of voids in sand. For 28
days' age of cubes, mixtures of one part Utica cement, two
parts of sand and varying proportions of broken stone gave
the following results for compressivjb strength per square
inch : Four parts stone, 680 pounds ; five parts, 910 pounds ;
six parts, 610 pounds; seven parts, 600 pounds. Similar re-
sults for other times of setting, from 1 day to 6 months, were
observed.

Practice is not yet settled as to the factor of safety to be
used, and it must depend to some extent upon the local con-
ditions, but in general it may be said that the safe loads for
various kinds of concrete may be obtained by dividing the fig-
ures for crushing strength given in this book by from 6 to 8,
unless the structure is subject to vibration, in which case 10 to
12 should be the divisor.

Variation in volume of cement packed and loose makes
much difference in proportions of cement in mortar, a point
which is frequently neglected in carrying out specifications,
even when it is properly taken care of in the specifications
themselves. In regard to this reference may be made to the
specifications for concrete of the Chicago & Alton railroad
in the chapter on "Specifications for the Use of Cement," and
also to the chapter on "Data for Estimates."

The excess in cost of laying a cubic yard of concrete with
dry mortar over that with wet mortar is shown by Herman
Conrow by figures from actual experience, as follows :

Cost of Cost of

Laying Wet Laying Dry

Concrete. Concrete.

Cement (1 barrel Portland) $1.50 $1,50

Sand 50 .50

Stone 1.00 1.00

Labor.... . 1.13 2.12

Totals , $4.13 $5.12

The gang for wet concrete was 1 foreman, 9 mixers, 1 ram-
mer, laying 15 cu. yds. a day. For dry concrete, 1 foreman, 6
mixers, 4 rammers, laying 8 cu. yds. a day. The foreman re-
ceived |2 and the men $1.50 a day.

THE USES OF CEMENT. 135

The question of the use of gravel in place of broken stone
in concrete frequently arises. Experiments reported in the
report of the Engineer Commissioner of the District of
Columbia for 1897 indicate that with natural cement the
gravel concrete has one-half to three-fourths the strength of
broken stone concrete, and with Portland cement there is but
little difference, the experiments being somewhat in favor of
broken stone. It is noticeable that there is a material in-
crease in the relative strength of gravel concrete with age so
that if the concrete is not to receive its load for some months
it will be very nearly as good as that made with broken
stone.

Mr. C. K. Neher, in a paper before the Engineers' So-
ciety of Western New York, reports tests of the compressive
strength of concrete of various materials as follows: in pro-
portions of 1 cubic foot of Portland cement to 2% cubic feet
of limestone between i/o-inch and 2-inch screens and 2y 2
cubic feet of lake gravel, the ultimate compression after 7
days was 135 tons per square foot. A mixture of one part
Portland cement with five parts of gravel gave 60 tons per
square foot after 7 days. Copper slag in place of the lime-
stone gave 80 tons, but with the amount of gravel reduced
slightly, as the breaks showed excess of gravel in spots, the
slag concrete reached an ultimate compressive strength of
over 140 tons per square foot in 7 days. Where weight is de-
sired the slag is valuable, as it weighs 3,300 pounds per cubic
yard for run of crusher against 2,800 pounds assumed for
limestone.

A discussion of the effect of size of sand upon the strength
of mortar by Mr. A. S. Cooper leads him to the conclusion,
based on experiments by himself and several others, that
coarse sands produce stronger mortar than fine sands up to
the size passing a No. 12 sieve and refused by a No. 16. Sand
passing a No. 50 sieve is all practically without variation in
its effect upon the strength of mortar. The shape and condi-
tion of the surfaces of the grains of different sands have as
much to do with their value for cement mortar as the size,
rough grains like crushed trap rock and granite being better
than those with smooth surfaces, and river sand being better

HANDBOOK FOR CEMENT USERS.

than beach sand. The proportions of mortar used in the tests
were usually one to one.

The effect of increase in amount of sand in mortar was
shown by a series of experiments at the Holyoke dam, Massa-
chusetts, upon an American Portland cement of the highest
grade. The results for tensile strength of mortar of various
proportions at the end of 28 days set in water were as fol-
lows :

Lbs. per
Sand to Cement. sq. in.

Neat cement 889

1 to 1 805

2 to 1 ... .... 589

3 tol 343

4 to 1 ... ... 204

Lbs. per
Sand to Cement. sq. in.

5 tol 133

6 tol 121

7 tol 71

8 tol 53

9 to 1.... .. 44

The effect upon strength of varying proportions of aggregates
in cement is shown by the following values for the modulus
of rupture of concrete beams in pounds per square inch, selected
by Taylor and Thompson from William B. Fuller's experiments
on 6-inch beams: In each case the proportion of cement to
total aggregate is 1 :6. If the proportions of cement, sand and
broken stone by weight are 1 :1 :5, the modulus is 504 pounds ;
if 1 :2 -Aj the modulus is 439 pounds ; if 1 :3 :3, the modulus is
355 pounds ; if 1 :4 :2, the modulus is 210 pounds ; if 1 :6 :0, the
modulus is 93 pounds.

VARIATIONS IN QUALITIES OF MATERIALS FOR CONCRETE.

Broken stone and gravel are compared in what has gone be-
fore. Other comparisons follow.

In a paper before the Engineers' Society of Western Pennsyl-
vania, Mr. Joseph A. Shinn describes the formation of what he
terms slag sand, by cooling the molten slag from blast furnaces
with jets of water under pressure. He gives a number of com-
parisons of the strength of this material in mortar with river
sand in the same proportions. His tests show that the tensile
strength of mortars made of one part Portland cement and
three parts slag sand are from 26 pounds at 7 days to 159
pounds per square inch at 3 months stronger than river sand
mortars of same proportions and ages. These increases in
strength are respectively 10.3 and 36.5 per cent, above the
strength of river sand mortars. With Louisville cement the

THE USES OF CEMENT. 137

gain with slag sand is not so pronounced, varying from 15
pounds or 34 per cent, at 7 days to 25 pounds or 21 per cent,
at 3 months. With lime mortars the increase is materially
greater, soft mortars with slag sand gaining 114 pounds or 771
per cent, at 28 days and 139 pounds or 580 per cent, at 3
months ; stiff mortars show gain with, slag sand of 126 pounds
or 371 per cent, at 28 days and 208 pounds or 441 per cent, at
3 months.

Numerous experiments in the laboratory and in practical
use have shown some increase in the strength of mortar made
with clean limestone screenings containing a considerable per-
centage of crusher dust in place of sand. Nelson A. Hallett
reports laboratory experiments in which he used the screen-
ings passing a sieve with 100 meshes to the square inch, con-
taining about 33 per cent, of fine dust. A rather wet mixture,
15 per cent, of water to 1 part of cement and 2% parts of
screenings by volume, thoroughly mixed and tamped as con-
crete is tamped gave results "easily 50 per cent, stronger than
the best sand mortar that could be obtained." These are re-
sults pf five years of experiment, some of the briquettes having
been kept three years in water.

The usual specification for sand requires that it be clean,
sharp, free from loam, clay or organic matter. The successful
use of sand containing from 3 to 7 per cent, by volume
of alkaline earth and organic matter in building the "Golden
Gate" viaduct in Yellowstone National Park, led Prof. C. E.
Sherman to make some experiments upon the effect of loam
and clay upon mortar. Dyckerhoff and Lehigh cements were
used in proportions of 1 of cement to 3 of sand. The standard
sand of the American Society of Civil Engineers, sand from
Lake Erie and bank sand were used. Part of the sand was
displaced by Mayfield, Ky., ball clay in some of the briquettes,
2, 4, 6, 8, 10 and 15 per cent, being used respectively. In an-
other set the same percentages of loam, common field soil from
a field in the Ohio State University campus, were used.
Roughly stated, the addition of 15 per cent, of clay increased
the tensile strength of briquettes 50 per cent, at 1, 2, 3, .4, 5, 6,
9 and 12 months, there being some variations above and below.
Also roughly speaking, the increases in strength were approx-

138 HANDBOOK FOR CEMENT USERS.

imately proportional to the percentage of clay in the sand.
With more variations in individual results, similar statements
will apply to the substitution of loam for part of the sand,
the maximum increase in strength being about 25 per cent,
with 15 per cent, of loam at 12 months. Of the different kinds
of sand, bank sand stood highest, the standard next and lake
sand last in about the average proportions of 6, 5 and 4.5.

Mr. J. C. Hain made for the Chicago, Milwaukee & St. Paul
railroad during three years many tests of sand from various
pits along the lines of the system to determine what sands
would be satisfactory for use in concrete work. He presented
a paper before the National Association of Cement Users, giv-
ing the results of his observations from which the following
conclusions are taken :

To sum up the situation, it is quite evident that clay in lim-
ited quantities (say not to exceed 12 per cent.) is beneficial if
thoroughly distributed throughout the sand. Before using,
however, it ought to be compared with an established standard.

Soil, on the other .hand, is detrimental. Sand containing
it shows up irregularly. Such sand should prove satisfactory
by tests before using.

Washed sand may be less desirable than unwashed. Wash-
ing removes the fine particles as well as the foreign material.
The fine grains, if not in excess, are needed to fill the voids of
the larger.

The only safe way to decide whether sand ought to be washed
would be to test it under both conditions.

A fine sand may show up well if the grains are well graded.
A coarse sand may show up poorly if there are too few fine
particles to fill the voids. The best graded sand is one in which
the grains held on a uniform series of sieves are so arranged
that the voids in one lot are filled, and not overfilled, by the
grains in the next smaller size, and so on. This grading
should begin with large grains in order to limit the surfaces
exposed to cement, and still these grains must not be so large
that the voids will not be filled with the smaller particles.

Briefly, then, the best mortar sand found in nature is one
with sharp corners, rough surfaces, with grains neither coarse,
medium nor fine, but with the proper mixture of all these sized
particles which will result in the least voids. The sand also
should not be washed, but may contain up to 12 per cent, of
clay which will not injure but will perhaps improve it.

Edward K. Coe, Assistant City Engineer, Duluth, Minn.,

THE USES OF CEMENT. 13

giv-es in a report to the City Engineer the following results of
tests, giving some indication of the proportion of clay which
may be used to advantage:

The sand used was standardized Lake Superior "clean, sharp
sand." The clay was red, dried, pulverized and thoroughly in-
corporated with the sand. The results here given are averages
of four and eight breaks each.
1 to 5 mortar, standardized sand, Atlas cement:

Age Per Ct. clay in
7 days. 28 days. the sand.

135 21 L none.

172 279 8

175 284 13i

153 220 21

1 to 5 mortar, Universal cement :

Age.

7 days. 28 days. 3 mos. 1 yr.

140 176 252 310 Clean sand.

203 301 402 10 per ct. clay in sand.

The following were made with an excess of water, and too
soft to ram.
1 to 5 mortar, Universal cement :

-Age.

7 days. 28 days. 3 mos. 1 yr.

104 ISO 204 251 Clean sand.

90 161 250 317 15 per ct. clay.

He says also that Louisville natural hydraulic cement in
every case gives the highest results with clear sand.

Mr. C. C. Huestis, Asso. M. Am. Soc. C. E., suggests in En-
gineering News that the fact that crusher dust, clay or loam
increased the strength of mortars made of 1 part cement and
3 parts sand, but diminished the strength of 1 to 2 mortar,
led him to the conclusion that the increase in strength is due
to the more complete filling of the voids in the sand by the
fine material so that the proportion of cement used was suffi-
cient to make the mass solid, while if the fine material is not
retained the cement is not sufficient in volume to fill all the
voids. Clean sand in mortar of proportions of 1 to 2 has its
voids completely filled by the cement and the addition of fine
material simply increases the proportion of sand in the mor-
tar and reduces the strength of the mortar in about the same
proportion. Washed sand in proportions of 1 to 3 or more
does not have its voids completely filled with cement. The con-

140 HANDBOOK FOR CEMENT USERS.

crete is therefore not homogeneous. Fine stone dust, clay or
even loam adds more to the strength of the mortar by reducing
the percentage of voids to what the cement can fill than it de-
ducts from it by reason of its quality. It will be noted that
all the experiments described above are upon mortars of 1 ce-
ment and 2y 2 to 5 of sand.

MORTARS OP CEMENT AND LIME.

The demand for mortars for building purposes containing
proportions of cement and lime has led the manufacturers of
Louisville natural hydraulic cement to put on the market
"Bricklayer's Cement," which is made by grinding 15 per cent:
of hydrated lime with calcined cement stone to a fineness of
92 to 95 per cent, through a No. 100 sieve.

Mr. E. S. Wheeler made some experiments to determine the
effect of lime upon Portland cement mortar, using proportions
of cement of 1 :3 to 1 :6 and percentages of lime to weight of
cement of 10 to 50. The addition of 10 per cent, of lime to
the 1 :3 mixture increased the tensile strength of the mortar at
3 months from 236 pounds per square inch without lime to 265
pounds with it. The substitution of 10 per cent, of lime for
the same weight of cement, making the proportion of cement
to sand 1 :3 1-3 and of cement and lime together to sand 1 :3,
gave a strength of 264 pounds per square inch. Further in-
crease in proportion of lime decreased the strength of the mor-
tar quite rapidly.

The lime must be thoroughly hydrated. Unslaked lime in
mortar may produce expansion of mortar or concrete and sub-
sequent disintegration.

CEMENT SIDEWALKS AND FLOORS.

Development of the use of cement in sidewalks has been very
rapid, and hundreds of miles of new walks are constructed
each year. Its use for this purpose has spread to the smallest
towns, which have in many cases constructed several miles
each in a single season. Full specifications as prepared for
use under the conditions in different parts of the country will
be found in the next chapter.

The question of foundation is one of much interest and
there are many expressions of opinion as to the depth of foun-

THE USES OF CEMENT. 141

dation necessary. The specifications in the next chapter show
what various engineers consider necessary. Albert Moyer, of
the Vulcanite Portland Cement Company, prepares three spe-
cifications under the following principles :

In laying a cement sidewalk keep constantly in view the fact
that the form of construction is artificial stone slabs or flags,
each slab subject to all the conditions surrounding artificial
stone, such as careful selection of materials, thorough mixing,
tamping and seasoning, allowance in the joints for expansion,
upheaval by frost and wear. Portland cement concrete ex-
pands and contracts with temperature changes in practically
the same ratio as steel. Upheaval by frost is obviated by pro-
viding an under drainage.

Specifications Nos. 1 and 2 : Sidewalks in cold climates or
where frost occurs, should consist of a foundation of coarse
cinder or broken stone extending below frost line, a concrete
base and a top coat or wearing surface.

Specification No. 3 for cement sidewalks in warm climates
where freezing does not occur: Excavate to a depth of 4
inches below established grade of the sidewalk, tamp the
ground well and evenly, omit the cinder or broken stone drain-
age foundation ; remainder of specification same as that for
sidewalks in cold climates.

With reference to the amount and quality of sand to be used
in the wearing surface of cement walks the following para-
graph from a letter by U. S. Assistant Engineer A. S. Cooper,
in Engineering News, is valuable:

A walk with a surface of neat cement is not as durable as
one with a mortar of one cement to one sand, because the ce-
ment is not as hard as the sand; and a mortar of one cement
to one sand is not as durable as one of one cement to two
sand, because in the former case the voids are more than filled
and some of the cement forms part of the wearing surface, and
will therefore wear out quicker than the mortar which has a
complete wearing surface of sand. The strength is derived
from the concrete below, and the life of the walk is entirely
dependent upon the hardness of the surface. The most durable
sidewalks are made from crushed trap rock, using the small
rock for concrete, and the finer particles with the dust screened
out, as sand for the mortar. This is not only the strongest
mortar 'and concrete that can be obtained, but also makes a
very hard surface, that will resist wear better than any other
sand. In making the mortar for the wearing surface the writer
would advise the use of - a large percentage of coarse sand, say
50 per cent, held on a 20 mesh sieve.

142 HANDBOOK FOR CEMENT USERS.

He also objects to the use of limestone screenings in the
wearing surface, as limestone is softer and less durable than
sand grains; but would permit the limestone screenings in the
base.

In England flagstones for sidewalks are made in factories
and set in place. The aggregates used are crushed granite
and limestone, also the clinker from garbage cremation plants.
The use of steel reinforcement, such as wire netting, expanded,
metal, bars, etc., in such flags has not yet extended very far,
and in this country the making of the walks in place is so
much more popular that the making and laying of concrete
flags is seldom heard of.

The use of natural hydraulic cement in the base of walks and
floors and of Portland cement in the wearing surface is recom-
mended by some contractors who have had good results with
this combination, but the great majority of those who have ex-
perimented in this method of construction report failures.
The great differences in rate of setting, in expansion or contrac-
tion in crystallizing and even in chemical actions set up strains
which are often too great for the walk to stand, and the two
kinds of concrete are separated from each other or one or the
other is cracked and by the aid of the weather is ultimately dis-
integrated.

Many inquiries are received asking the best method of repair-
ing or renewing a cement walk or floor, the surface of which
has been worn off or broken on account of hard usage or defec-
tive construction. The replacing of the wearing surface with-
out removing the base and replacing the entire thickness of
concrete is difficult. There is occasionally a cement worker
who meets with success, but usually the 'permanency of the re-
pair can not be predicted. The essentials seem to be perfect
cleanliness of the old concrete surface, all loose particles and
dust being completely removed, thorough Avetting of the old
concrete, a thin coat or wash of neat Portland cement on this
wet surface, followed, before the cement has set, with the wear-
ing surface coat.

The use of cement for concrete floors in stables, cattle and
hog pens, breweries and factories, where a smooth, durable
surface is required, has developed equally with its use for

THE USES OF CEMENT. 143

sidewalks. It makes an ideal floor for almost all such pur-
poses, is easily repaired when cut entirely through for any pur-
pose, and is practically indestructible when properly con-
structed, except for wear of traffic. Special care must be taken
to allow for expansion and contraction when there are great
variations in temperature, and special construction to insure
water-tight joints is necessary in such cases. Ample joints
filled with asphalt or similar elastic and water-proof material
are nearly always satisfactory. In case a floor must be at
the same time water-proof, a layer of continuous asphalt or
other water-proofing under the concrete blocks will answer the
purpose. Slight inclination toward one side or corner or
outlet conveniently placed will often aid in removing the
liquid reaching the asphalt layer and thus reduce the cost of
repairs. There are several special devices for laying wooden
floors in stalls where horses stand, to add to their comfort and
protect the concrete from the constant wear of their steel shoes.
The wooden portions should be readily removable for cleaning
and renewal.

CONCRETE ROADWAYS.

Street crossings of cement concrete are made in some
smaller cities whose streets are not paved, and they are a
sufficient improvement over the usual wood or flag stone
crossing to repay the increase in cost. They are made accord-
ing to the specifications for driveways in the next chapter,
with wings or approaches on each side, on a slight slope, ex-
tend down into the earth on each side a distance depending
upon the depth of mud in wet seasons, that wagon wheels
may not strike the edges of the concrete and disintegrate
them.

Pavements for driveways to public and private stables, to
railroad freight stations, factories, storehouses, etc., are
equally valuable and their use is rapidly increasing.

In New Orleans the neutral ground on Canal street was
paved with concrete in 1901. This neutral ground is 60 'feet
wide in the center of a street 170 feet wide and contains five
street car tracks. Concrete is placed under the railway tracks
and between the ties and on top is laid 4 inches of concrete of
one part Portland cement, three parts sand and seven parts

144 HANDBOOK FOR CEMENT USERS.

TRACK CONSTRUCTION. NEW ORLEANS CONCRETE PAVEMENT.

NEW ORLEANS CONCRETE PAVEMENT.

THE USES OF CEMENT. 145

broken stone with one inch top layer of one part Portland ce-
ment and one part sand. Sand joints in the concrete and tar
paper joints in the top divide the pavement into blocks and
there are 8-inch sand joints next the rails as shown in the ac-
companying cuts. The cost was 25 cents a square foot. Com-
plaint has been made of the excessive heat from the reflection
of the sun and it has been found necessary to keep the pave-
ment wet on this account during the hot season.

In 1903 City Engineer W. J. Hardee reported upon failures
in some portions of the pavement, attributing some of them
to settlements in the railway tracks extended by the vibrations
of running cars under the changed conditions produced by the
settlement. Some of the pavement failed because the top
course was not thoroughly bonded with the bottom course
and the great heat to which the pavement surface is subjected
in summer separated the two layers on account of the weakness
of the junction, which could not stand the strains set up by the
differences in expansion of top and base. Part of the top course
was delayed so that it could not be laid before the base had sec.
Some of the area thus delayed is in good condition, showing
good bond of base and top, while part of it has failed as de-
scribed. This pavement is not subjected to vehicle traffic.

The city of Belief ontaine, O., has constructed several blocks
of concrete pavement, the first of which, laid about 1890 ; is still
in very fair condition. The specifications for the pavement
were practically the same as those for cement driveways given
in the next chapter. A square yard of the pavement required
144 pounds of cement and 4 cubic feet of gravel.

Grand Rapids, Mich., has recently built several short concrete
pavements on narrow streets on similar specifications.

Toronto, Canada, has laid several concrete pavements with
specifications and cross sections as shown in the next chapter.
Jiiclnnond, Ind., has entered upon this class of construction and
quite full specifications are given in the same place.

In various parts of England, Germany and other European
countries concrete macadam pavements have been laid, made
of 1 part Portland cement and 4 parts broken stone, laid in two
layers each 3 or 4 inches thick in the center of the street and
1 inch thinner at the sides. Some of them have failed promptly

146

HANDBOOK FOR CEMENT USERS.

and some have lasted ten years without repairs, but they are
not popular.

CURB AND GUTTER.

Since the invention of the Parkhurst combined curb and gut-
ter the use of cement for making street curbing has increased
very rapidly. Over 120 miles of the Parkhurst curb and gutter
alone have been constructed during the last ten years, and
many miles of concrete curb and gutter and of curbing alone.
The combination of curb and gutter solves a problem for mac-
adam streets by giving a smooth gutter for drainage, and for
asphalt by removing the danger of injury to the asphalt sur-
face by water standing in flat or in obstructed gutters. The
appearance of well-constructed curb is much in its favor, and it
is more durable than most kinds of natural stone, the use of
which is popular in some districts. The addition of strips of
steel to take the wear on edges and face is made with success
where the amount or character of traffic makes this precaution
necessary for either stone or concrete curb, and the metal is
most easily put in place and kept there when the cement curb
is used.

The following diagrams show two somewhat different meth-
ods of laying concrete walk, curb and gutter.

CROS3-SE*nON OF COMBINED CEMENT CuRS AND GuTTEF

TWO DESIGNS FOR CONCRETE WALK, CURB AND GUTTER.

In a description of the construction of the Forbes Hill reser-
voir at Quincy, Mass., Mr. C. M. Saville states that the bottom
and slopes were lined with concrete. The bottom layer of con-
crete was made of cement, sand and broken stone in proportions
of 1:3:6. When this was finished a layer of Portland cement
plaster made of 1 part Portland cement and 2 parts sand, with
a finishing surface of 4 parts cement to 1 sand, was laid in strips

THE USES OF CEMENT.

147

about 4 feet wide and finished like a granolithic walk. Long
strips of coarse wet burlap were used to keep this layer wet and
cool, but some cracks appeared. They were thoroughly grouted,

WAINWRIGHT STEEL BOUND CONCRETE CURB AND GUTTER.

and the top layer was then put on. It was laid in alternate
blocks. These blocks were 10 feet square for the bottom of the
reservoir and 8x10 feet on the slopes. When the first set of
blocks had hardened the remaining blocks were laid. These
blocks were made the same as the bottom layer except that for
the stone in top arch was substituted stone dust and fine broken
stone, passing through a %-inch screen, laid before the base of
the block had set.

The accompanying illustration shows the method of placing
the groined concrete floor and roof of the water filter basins at
Philadelphia, Pa.

SUBWAYS, TUNNELS AND SEWERS.

The use of concrete and cement mortar for lining subways
and tunnels is rapidly extending. The surface can be made non-
absorbent, smooth and light colored where distribution of light
is desirable, is quite as durable as stone or brick and usually
more pleasing to the eye. By far the most extensive use in this
way is in the subways of the New York Rapid Transit Railway.
It was used to a large extent in the construction of the Boston
subways. Samples of the specifications for concrete for this
class of work will be found in the next chapter. The subways
in Boston have also been largely constructed of concrete and
reinforced concrete.

The Aspen tunnel on the Union Pacific Railway, in exceed-

148 HANDBOOK FOR CEMENT USERS.

ingly difficult ground, was lined with 6-inch steel ribs 2 feet
apart, surrounded and filled in with concrete. Another inter-

PHILADELPHIA FILTER BED UNDER CONSTRUCTION. CONCRETE FLOOR AND PIERS
AT LEFT. CONCRETE GROINED ARCH ROOF AT RIGHT.

esting application of a concrete lining of a tunnel with steel
beams in the soffit is found in the Third-street tunnel in Los
Angeles, Gal. The special form of specification used will be
found in its proper place in the next chapter.

The Musconetcong tunnel on the Lehigh Valley Railroad in
New Jersey was lined with concrete without stopping the run-
ning of trains. A traveling platform was erected on rails
along the side of the tunnel 'for making the necessary excava-
tions. Following this, forms were erected in 16-foot sections
on the face of the completed tunnel and concrete was filled
behind them as they were built up until the springing of the
arch was reached. Then posts were put in to support the plates
on which the steel arch ribs were rested, the centering and lag-
ging was put in place and the concrete deposited for the arch
and its filling on each side until the crown was reached, the
centering being braced as necessary to keep it from rising at
the crown from the load of green concrete on the sides. The
arch was laid in 10-foot sections carefully, as the bracing for
the centering was very light on account of the necessity of leav-
ing room for passage of cars. Each section was allowed to set

THE USES OF CEMENT. 149

until hard before the next section was begun. Where water
was encountered 3-inch iron pipes were placed in the concrete
to drain it into the drainage channel of the tunnel.

Concrete has been used for sewers in Europe for many years.
In the United States comparatively little use has been made of
abandoned it. New York ; Boston ; Wilmington, Del. ; Salt Lake
City, Utah; Vancouver, B. C.; Coldwater, Mich., and Chicago
railroads have all been users of concrete to some extent and ex-
amples are also to be found in Texas and elsewhere.
The city of Washington, D. C., has the most elaborate specifica-
tions and is at present the largest user of concrete for the larger
sizes of sewers. Circumstances dictated a peculiar meth-
od of constructing sewers in Coldwater, the invert being a
concrete monolith and the arch built of concrete blocks made in
a yard at leisure and put in place in the same manner as stone
blocks.

The main outlet sewer of the Chicago Transfer and Clearing
Yards was built as a monolith, sewers from 36 to 48 inches
diameter having 8-inch walls, and those 84 and 90 inches in
diameter walls of 12 inches thickness. The invert was laid on
a sub-grade carefully made and brought to proper surface by
suitable tamping, troweling and smoothing with templets.
After the invert had set the center for the arch was put in place.
It consisted of circular ribs resting on the invert and support-
ing 2x4-inch lagging with edges planed to radial lines. Con-
crete was rammed on this centering and brought to proper
thickness by means of templets. This would seem to be a sim-
pler and cheaper construction for the arch than that using
concrete blocks.

The list of cities using concrete for sewers is extending rap-
idly. A few of those using plain and reinforced concrete in
addition to those already named are Newark, N. J., Beverly,
Mass., Cleveland, O., Indianapolis, Ind., Truro, N. S., Corning,
N. Y.

Walter C. Parmley, of Cleveland, O., is the inventor of a sys-
tem of reinforcing concrete sewers and also of reinforced con-
crete blocks for building sewers and conduits. The blocks are
conveniently made as quarters of the perimeter of the sewer
and of any length desired. They have grooves in which rein-

150 HANDBOOK FOR CEMENT USERS.

forcing rods can be laid in mortar similar to the reinforcement
in the monolithic sewer, around the barrel of the sewer and
longitudinally, binding adjacent blocks together.

In the construction of the tunnel of the New York Eapid
Transit Kailway many sewers must be reconstructed. In a
number of instances they have been built of concrete molded in
place at a cost about one-third less than brick sewers. Forms
were used for making the inverts consisting of strong frame-
work and closely matched planed lagging greased with machine
oil. Forms for arches were similar. They were made 12 feet
long. The concrete was first put in place and brought within
% inch of the grade, a template being used as a guide. The
form was then accurately set in position and the remaining
,space filled with 1 to 1 Portland cement mortar. The form was
then braced by struts to the sheeting of the trench and vertical
planks set for the outside of the spandrel wall. Concrete was
then carefully rammed in and made smooth. After 24 hours
or more the form was withdrawn and a thin cement grout
brushed over the surface. Concrete was in proportions of 1 :2 :4,
Portland cement, sand and broken stone 1 inch and less. When
arch centers were put in place the lagging was first plastered
with 1 inch of 1 to 1 mortar, and concrete was then rammed
in to a depth of 8 inches. Side forms on slope kept the side
concrete in place and the crown was formed by hand. Some
sewers had concrete invert and brick arch.

The borough of Brooklyn, New York, formerly used cement
pipe in sewers. This practice seems to have been discontinued,
but the sewer department is now using concrete very exten-
sively in constructing large storm water and outlet sewers in
open cut and tunnel. Concrete lends itself most readily to the
peculiar constructions necessary at junctions, overflows, con-
nections with intercepters, and the like, and, with reinforce-
ment where most needed, is more readily put in place, carries
the loads with more satisfaction and reduces the cost. It would
be necessary to devote a large part of the book to this system
if an attempt were made to show the many interesting features
of the designs and methods of construction.

WATER AND SEWER PIPE.

Cement mortar has been used with more or less success as a

THE USES OF CEMENT. 151

lining for light steel or iron pipes, the cement preserving the
steel from corrosion and keeping the pipe constantly of the
same area of cross section. Owing to errors when making con-
nections, and other similar reasons, this construction has never
been very popular and it is now seldom used.

Cement pipe reinforced with wire cloth, expanded metal or

CEMENT SEWER PIPE.

steel rods, according to the size, strength required and system
of reinforcement adopted, are made for carrying water under
pressure. These pipes are sometimes made in place and some-
times made in sections and laid and jointed as other pipes are
placed.

Sewer pipes are made in molds, the concrete being tamped
by hand or compressed by hydraulic or other power. Occasion-
ally they are reinforced with steel, but ordinarily they are given
sufficient thickness so that concrete alone is required. The
pipes are laid in the same way as other sewer pipes.

PIERS, BREAKWATERS, DAMS, LOCKS A*ND OTHER MASSIVE MONO-
LITHIC CONCRETE STRUCTURES.

Bridge piers are frequently constructed with a heart of
cement concrete and in rapidly increasing numbers are con-
structed entirely of such material, the exterior receiving a coat-
ing of Portland cement mortar specially prepared with the best
of materials. One recently constructed in Tennessee is entirely
of concrete made with 1 part Portland cement, 3 parts sharp
sand and 5 parts broken stone to pass through a 2-inch ring,
and is 63 feet high, 24 feet wide .under the coping, 8 feet thick,

152 HANDBOOK FOR CEMENT USERS.

with a batter of % inch to the foot. This is the highest con-
crete pier in this country.

The conservative railway managers are rapidly extending
the use of cement and concrete for all railway structures, and
it is not impossible that within a comparatively short term of
years nearly all structures from pipe culverts to station build-
ings on some railroads will be at least externally of concrete.

There are several notable examples of the use of monolithic
concrete for such structures as the walls of canal locks, and
some instances of the use of blocks made of concrete and set.
in place after completion.

In the construction of piers and breakwaters cement has been
used very largely in recent years. Very large blocks of concrete
stone are built, sometimes in place and occasionally elsewhere,
and then laid in place as natural stone blocks would be. Heart
walls and filling may then be constructed of concrete laid in
place. Some specifications for this class of work follow in the
next chapter.

The dam of the Lynchburg, Va., water works is of the gravity
type. Its crest is 415 feet long, of which 150 feet is a spillway.
The maximum height above bottom of foundation of the main
dam is 66 feet and maximum bottom width 39.25 feet. The
maximum section of the spillway has about the same height
above the foundation and a bottom width of 44.25 feet. The
down stream face is stepped. The crest of the spillway is 10.5
feet above the top of the dam. The masonry is of concrete
blocks in which large stones are imbedded. The blocks are rec-
tangular and irregularly shaped on such designs as insure
thorough bedding. The outside blocks are made with Portland
cement, and those within with natural hydraulic cement. The
wing walls each side of the spillway, the gate chamber wall and
the parapets are reinforced with square twisted steel rods. The
down stream edge of the spillway crest is of cut stone and the
treads of the spillway steps are of granite blocks. See next
chapter for specifications for blocks.

A solid concrete dam has been built across the Maquoketa
river at Manchester, Iowa. It is 185 feet long, about 101 feet
being from 9 to 11 feet high and the remainder 1.5 to 9 feet.
The back of the dam is vertical except for a batter of 1 in 10

THE USES OF CEMENT. 153

where the sluice gates are located. The top of the dam is 3
feet wide and has a 10 by 10 inch pine timber bolted on the crest
and a G by 6 inch on the rear of the top, with 2-inch planking
between to take the shock of floating ice. A flash-board 2 feet
high can be raised on the outer timber. The base is 9 feet wide
and the face is a reversed curve. The concrete is of 5 parts
good gravel to one part Portland cement, this proportion being
slightly more than enough to fill the voids. Although there
was no plastering of rich mortar on the back of the dam, it is
tight. The faces of the dam were tamped with oblique tampers
and are smooth and dense. Cement cost fl.50 a barrel and
gravel 50 cents a cubic yard, and the contractor's bid on labor,
forms, etc., was $2.50 a cubic yard of concrete. The volume
of the dam was 260 cubic yards, and it required 280 loads of
gravel and 350 barrels of cement, and was built in 15 days.

A concrete sea-wall at Scarborough, England, which has
taken seven years to build, has recently been completed. It is
built of about 1,500 concrete blocks weighing 2 to 9 tons each.
Its length is 4,200 feet, height 40 feet, width at foundation 30
feet, and at top 10 feet.

Wm. Watts, an English engineer, recommends concrete in-
stead of clay puddle for an impervious core to an embankment
or earth dam, more especially in the trench made in the founda-
tion of a dam, which is sometimes required to carry the core
down to an impervious stratum, so that there will be no leak-
age under the dam. He prefers clay puddle for the core of the
embankment above.

At Barossa, South Australia, is an arched concrete dam 472
feet long on the top, with a radius of 200 feet, a height of 95
feet above the ground line, 4.5 feet thick at the top and 34 feet
at the ground line. It is built of concrete with about 5 cubic
yards of granite boulders placed by hand not less than 6 inches
apart in every 30 cubic yards of concrete, and about 40 tons of
old rails in the upper 15 feet of the dam where it is too thin to
warrant placing the boulders. Observation of extremes of 50
degrees in temperature on 6 different days showed an expansion
of the length of the top of the dam of about 1.5 inches and a
motion of the crown up stream of % inch.

The new Walden Pond dam of the Lynn, Mass., water works

154 HANDBOOK FOR CEMENT USERS.

is of earth with a concrete core wall. Below the base of the
wall sheet piling was driven to hard material, about 18 feet
down. The foundation of the concrete core wall was begun 3
to 6 feet below the top of this piling, the top of the piling being
19 feet below the original ground surface and 70 feet below
the top of the dam, or 67 feet below the top of the concrete. The
foundation is 9.5 feet thick and reduces to 8 feet before the
ground surface is reached and to 4.66 feet at the top. Concrete
was mostly 1 part Portland cement, 2 parts sand and 5 parts
gravel, mixed with Dromedary mixers, gravity mixers and by
hand. About 20 per cent, of the wall is composed of boulders
up to 2 cubic yards volume, bedded in the concrete. The front
face is plastered with 1 to 1 mortar. The earth filling was de-
posited in layers and puddled or rolled. The entire dam will
be 2,200 feet long, 200 feet wide at the base and 52 feet at the
crest. The pond being filled by pumping, there is no spillway.

BUILDINGS AND PARTS OF BUILDINGS.

Every city now has examples of houses, stores, factories and
other buildings constructed wholly or in part of concrete.
Foundations, walls, floors, roofs, partitions are all in use and
may be made solid or hollow, monolithic or of blocks, of plain
concrete or reinforced with various forms of steel. Descrip-
tions of a few to indicate the various materials and methods
of construction are given. Where the descriptions partake of
the nature of specifications they are given in the following
chapter.

Many handsome buildings have recently been constructed
in Florida of a concrete made of Portland cement and coquina
shells from the vast deposits of that material on the seacoast
of that State.

Some Northern Pacific railway stations are notable exam-
ples of concrete construction. In one case the walls are hollow,
two walls each 5 inches thick, and an 8-inch space between, with
4-inch cross walls every 2 feet. Tower walls are solid and 18
inches thick. The foundations were made of broken stone or
gravel concrete in proportions of 1 :3 :5. The walls were made
of gravel concrete in proportions of 1 :2 :5, with a facing 2 inches
thick made of 1 part cement, 1 part sand and 3 parts marble
chips. The walls were laid up inside the forms in layers 10

THE USES OF CEMENT.

155

inches thick, and before the cement was too hard the entire out-
side surface was brushed over with a steel brush, making the
surface rough and exposing the marble chips.

The shops and roundhouse of the Central Railroad of New
Jersey at Elizabethport have recently been built of concrete
with steel reinforcement, where desired, from foundation to
roof, both inclusive.

Many factory buildings are built like the mills of the Lehigh

CONCRETE SHELTER HOUSE, RIVERSIDE PARK, INDIANAPOLIS, IND.

Portland Cement Company. The proportions for the concrete
in this case were 1 part Portland cement, 4 parts sand, 8 parts
crushed stone and 2 l / 2 parts rough stone, one barrel of cement
making 1.35 cubic yards of concrete. As the concrete was de-
posited the rough building stones, weighing from 30 to 50
pounds, were bedded in it, the concrete being well rammed
about them. A cubic yard of the concrete was found to consist
of 295 pounds of cement, 880 pounds of sand, 2,400 pounds of
crushed stone and 700 pounds of rough building stone. The
walls were left rough as they came from the forms, except
about the windows, which were finished off with cement and
sand. The walls can be smoothed somewhat by applying with
a whitewash brush a coat composed of cement and lime. A
much better finish can be given by plastering the surface with

156

HANDBOOK FOR CEMENT USERS.

a mortar of 1 part Portland cement and 3 parts fine, sharp sand,
using a mason's wooden trowel. The thickness of the walls
varies with the height. One 45 feet high is 17 inches thick for
the first 30 feet and 12 inches for the remainder. Those 16 to
25 feet high are 10 to 12 inches in thickness. The forms for
placing the concrete were made of 1%-inch boards held in place
by a framing built up of scantling 3 inches wide by 6 inches
and 3 inches bv 8 inches, and IVo-inch boards. The frames for

FORMS FOR BUILDING SOLID CONCRETE WALLS.

the two sides of the wall are built up together and bolted to-
gether through the uprights, and the concrete is filled in as
the framework rises. When the concrete work is done the
frames are taken down,, the bolts are removed and the holes
filled with cement mortar.

The walls of the power house of the Virginia Electric Kail-
way and Development Company at Richmond, Ya., were built
of massive concrete blocks molded in boxes, where they were
allowed to remain until set. They were lifted by means of
irons running through them and bearing on thin iron strips
imbedded in the bottom, as they were moved before full strength

THE USES OF CEMENT.

157

was developed. Such special forms as cornices, window courses,
etc., were molded separately for architectural effect.

In foundation walls it is well to insert wooden pins of proper
size where water, gas and sewer pipes are expected to enter, as
the concrete is very difficult to cut. .

Portland cement tiles for floors, bases of walls, and special
uses have been made for a number of years. Colors are readily
used as desired, and no heat being necessary, form and color
may be as exact as is desired. Roofing tile of Portland cement

SHELTER HOUSE OF HOLLOW CONCRETE BLOCKS, MILITARY PARK,
INDIANAPOLIS, IND.

are also very successful. They are light, durable, fire-proof, not
breaking on contact with water when white-hot, and frost-proof.
They are compressed under very heavy pressure and can be
made of any desired shape or color.

CONCRETE BLOCKS AND MACHINES FOR MAKING THEM.

One of the most rapid growths in the cement trade has been
that of the use of concrete blocks. Although Mr. H. S. Palmer
had been at work upon the development of the first practical
machine for making hollow concrete blocks for some ten or
twelve years prior to 1902, there was no pronounced effort to
extend the use of the machine until January of that year. In
but little more than three years the industry has grown until

158 HANDBOOK FOR CEMENT USERS.

the number of patents on machines and blocks now approxi-
mates one hundred, and there are probably 2,000 manufactur-
ers of the blocks more or less actively engaged.

There are two principal methods of making the blocks, the
dry and the wet. By the dry method the materials are mixed
with the smallest practicable amount of water and are thor-
oughly tamped into the molds. The blocks are made on pallets
on which they can be carried away from the mold or machine
as quickly as they have been formed, thus leaving the machine
ready to make another block. It is therefore possible to make
blocks by this process as rapidly as the sides of the machine
can be put in place, the mortar mixture tamped into it, the
mold opened and the block on its pallet removed. The expense
for apparatus is thus reduced to a minimum and the speed of
operation is limited only by the number and expertness of the
operators, the facility with which the machine can be handled
and the convenience of the plant for handling the raw materials
and the finished product.

The simplest machines are merely molds with removable
sides, ends and cores, and there are many methods of combining

A SIMPLE BLOCK MOLD.

and operating these elements. In some cases the machine or
mold is moved away from the block, rather than removing the
block from the machine. Other machines have mechanical de-
vices for raising and lowering cores and blocks, for operating
the removable sides and ends of the mold, for lifting and trans-
porting the blocks, etc. This gives opportunity for the applica-
tion of much inventive genius and the variety of machines is
added to at least monthly. The tamping may be done by hand
or by mechanical tampers, of which there are several designs on
the market, handled in various ways. A few machines apply

THE USES OF CEMENT.

159

pressure to the blocks instead of the tamper, some by means
of levers operated by hand or by machine, others in hydraulic
presses.

A BLOCK MACHINE WITH CORES REMOVED BY LEVER AND FORK FOR
COMPLETED BLOCKS.

Some of the molds are fixed in size, fractional blocks being
made by inserting plate partitions, and a different mold being
required for each size or shape of full-sized block. Others have

it,

A MACHINE FOR MAKING PRESSED BLOCKS.

adjustable beds on which various sizes and designs of side and
end plates and cores can be operated. Others are adjustable in

160

HANDBOOK FOR CEMENT USERS.

all dimensions with the help of some extra plates. The forms
and sizes of blocks are endless in their variety, each inventor
having his own ideas of the best form and size of block. Some
have worked out in detail all nossible forms of blocks for

VARIOUS FORMS OF TAMPED HOLLOW CONCRETE BLOCK.

straight walls, pilasters, corners, bay windows, chimneys, chim-
ney breasts, window and door caps, sills and sides, string
courses, water tables, cornices, etc., and are prepared to fur-
nish anything which may be needed for any sort of building.
There is but little uniformity in the blocks on the market, and

ONE FORM OF PRESSED HOLLOW CONCRETE BLOCK.

yi fact in some instances there seems to have been an effort to
make blocks which cannot be used with those made on any other
machine.

By the wet method the blocks are cast in molds, in which
they must remain for some hours or days until they have set,
while the blocks made by the dry process can be removed on

THE USES OF CEMENT.

161

pallets as soon as formed. Molds are made of wood, iron or
steel, or in some systems of sand. The molds with solid sides
can be used indefinitely, a number being required sufficient to

A CAST STONE BLOCK.

keep the working force busy until the cement has set and the
molds can be removed to use aain. Sand cores are sometimes

iff in 11 ii I
ii f 1 1! ii ii f 1

AN OFFICE BUILDING OF HOLLOW CONCRETE BLOCKS.

used to take up some of the excess of water in the concrete and
hasten the time of setting. According to two or three systems

!62 HANDBOOK FOR CEMENT USERS.

sand molds are used, partly to give a special texture to the
surface, partly to regulate the amount of water automatically
to the requirements of the cement in crystallizing, and in one
instance, it is claimed, to apply a chemical for hastening the
hardening of the surface.

This is not the place to make suggestions regarding the op-
eration of cement block plants, but it may be well to make some
suggestions regarding the materials and methods of manufac-
ture of blocks.

A concrete block wall should be as nearly waterproof as pos-
sible. Stone or brick masonry walls absorb water from the
atmosphere, and it is necessary to use studding and lath, or
devices producing the same results in order to preserve plaster-
ing. The ordinary concrete block made by the dry process is
of the same porous nature. If the plastering is to be put di-
rectly upon the inner surface of the concrete block wall, the
passage of water through the block must be prevented. The
hollows in the ordinary concrete block are there to save con-
crete and to save weight of block, the thickness of wall required
for lateral stability being greater than is necessary for carry-
ing the weight on the w r all, if made solid. Some have assumed
that these hollows would make the wall waterproof, but it has
been learned from experience that the moisture passes through
the remaining concrete and reaches the inner surface of the wall
unless other precautions are taken. One form of block has two
rows of hollow spaces, staggered, so that moisture must follow
a to/rtuous course in reaching the inner surface. Several man-
ufacturers make blocks in two pieces, which together make a
hollow wall, the two tiers of blocks being bonded together in
various ways, and the passage of water through the wall being
prevented by the lack of continuity of block through the joint,
even, it is claimed,, if the joint is made with a dense cement
mortar which holds the blocks firmly together. There are sev-
eral preparations for making blocks waterproof which are de-
scribed under the head of "Waterproofing Concrete." One
very important adjunct to all these methods of keeping water
out of a wall is the density of the block itself. This should be
the first consideration in determining the proportions of ma-
terials to be used in making blocks, and it is in reality given

THE USES OF CEMENT. 163

no thought whatever by the average block maker. It is pos-
sible to make concrete waterproof by using the proper propor-
tions of cement, sand and gravel and working the mixture with
the proper amount of water and with the proper attention to
the finishing of the outside surface, as elsewhere described in
this chapter. It is not commercially practicable to take this
care of the surface of a hollow block nor to use the full amount
of water desirable in blocks made by the dry process, so that ap-
proximation to water tightness is all that can be made.
The most satisfactory mixture of gravel or broken stone,
sand and cement must be determined by experiment with the
materials to be used, according to the principles stated else-
where in this book.

Faces of blocks must be of pleasing designs, architecturally
correct. They must be well finished, by using proper molds,
by tamping faces thoroughly, using better materials for the
face if the best appearance is to be secured at lowest cost, and
by carefully removing molds, and handling blocks so that faces
and edges shall show no marks of cement sticking to molds or
of careless marring. Crazing or hair cracks appear on faces
sometimes because blocks are subjected to changes in tempera-
ture before the surfaces are fully cured, and sometimes because
there is an excess of cement on the surface. Brushing of the
surface at the exact stage of hardening which is best will im-
prove the faces in this regard. Experiment is necessary to
learn the exact time for the conditions of temperature, setting
time of cement, amount of moisture, etc.

Each machine has its own method of operation and its own
best kind of mixture, so that only general directions can be
given here. The materials, when the best proportions have been
determined, must be mixed thoroughly. The small plant can
not afford a power mixer, and must take all the more pains.
Too much must not be prepared at a time, so that partial set
takes place in the pile while standing, thus weakening the
block, and especially preventing thorough consolidation.

Blocks must be made on a hard floor, that no dirt may get
into the concrete, and the floor must be kept clean that no
lumps of partially or wholly hardened concrete may get into
the concrete and prevent consolidation of the block. Molds

164 HANDBOOK FOR CEMENT USERS.

and tools must be kept perfectly clean and should be wiped
frequently with an oiled cloth to keep them smooth and prevent
sticking, care being taken not to discolor the face of a block
by using too much or too dirty oil.

Blocks are very often injured by jars in handling, especially
in taking out of the machine and in setting in rack, also on
cars running on a rough track. The blocks must be stored for
the first few days where the changes in temperature will be as
slight as possible, and should be protected from the direct rays
of the sun. At the same time they must be so stored that they
can be sprinkled thoroughly without danger of injury to the
faces. Blocks are often rushed into the wall too quickly and
careless handling mars their appearance. There are several
preparations on the market for hardening blocks quickly,
whose composition and mode of action should be fully known
before they are used in important work. If the substance acts
by setting up a favorable chemical action and crystallization
ical which ultimately produces a disintegration of the cement-
ing substances in the concrete, the ability to handle blocks
and hastening it, there can be no objection, provided there is
not a future reaction; but if this action is produced by a chem-
quickly is gained at too great a cost of reduction in durability.
Some of these substances also contain matters which are sol-,
uble in water and produce efflorescence and discoloration.

ARCHES.

Many arches have been constructed of concrete without any
steel reinforcement. One at Westvale, Mass., has a span of 66
feet and a clear roadway of 35 feet. The arch is a semi-ellipse,
with a rise of 11 feet. The foundations of the abutments rest
on firm gravel and sand, the concrete composing them being
made of sand and gravel from the vicinity in proportions of
1 :3 :6. The gravel ranged in size up to 4 inches. The center was
built of old material from the replaced bridge and the lagging
was 2-inch planed spruce plank matched and put together
closely. The arch concrete was made with gravel of 2 inches
diameter and less in proportions of 1:2:4, hand mixed. Fail-
ures to make a smooth surface next to the lagging were reme-
died in the hardened concrete by cutting out pockets, setting
in half-inch bolts with nuts on for anchors and filling the

THE USES OF CEMENT.

165

pockets with concrete to a smooth and regular surface.
After everything had set the entire face of spandrel walls
and arch ring was dressed to line by stone chisels, which
gives a fairly good appearance.

A concrete arch of 14 feet at Piqua, O., was constructed on
a center formed of earth filled into the opening between the
completed abutments so that its upper surface was the form
of the soffit of the arch. The concrete was filled in on a layer
of 1-inch boards and tar paper, wooden forms on the sides
giving the side walls. A 3-inch layer of 1 Portland cement, 2
fine crushed stone and 5 coarse broken stone was spread
first, then 6 square iron rods of 1 inch cross section were
laid on from one abutment to the other, being 3 feet apart.
The concrete was then filled in to give an arch 16 inches
thick at the springing line and 10 inches at the crown, and
side walls 10 inches thick. The facing of the walls, laid at
the same time, was made of 1 part of cement and 2 parts of
stone dust and was 1 inch thick.

Quite an elaborate arch bridge of two spans was built by
the Central Railroad of New Jersey at Northampton, Pa.,
using sheets of expanded metal laid in radial lines similar
to the radial joints in a stone arch and four joints of the
same sort made with sheets of paper, two on each side of

A CONCRETE ARCH.

166 HANDBOOK FOR CEMENT USERS.

the crown, running entirely through the arch masonry. The
molds were built of 2-inch plank planed on one side and
nailed to 3x5-inch and 4x6-inch studding on 3 to 3V2-foot
centers. The braces were made of 2x9, 4x6 and 6x6-inch stuff.
Proportions of cement were 1 cement, 3 sand, 6 slag from
%-inch to 2V2-inch screen in foundations ; 1 :3 :7 in wings ; 1
cement, 2 sand, 4% to 5 broken stone, from 1/4 to 2y 2 inches
in arch ring and parapet; and 1 cement, iy 2 to 2 sand in
facing. All cement was Portland cement made in the neigh-
borhood.

The concrete viaduct of the San Pedro, Los Angeles and Salt
Lake railroad near Kiverside, Cal., is a notable example of
plain concrete work. Its total length is 984 feet, width 17
feet, and average height 55 feet. There are eight main arches,
each of about 87 feet span and 37 feet rise; piers are 16 by 28
feet at the footings; approaches are double retaining Avails
connected with the abutment by an arch of 38.5 feet span.
Local cement and washed bank gravel in proportions of 1 to
11 were used in foundations, piers and spandrel walls. For-
eign cement, sand and crushed rock were used in the arch rings
in proportions of 1, 2 and 4.5. "Standard" (California) Port-
land cement was used in coping and parapet walls. There is
probably but one longer concrete viaduct, the Glenfinnen iir
Scotland, which is 1,248 feet long.

On the St. Louis and San Francisco railway concrete bridges
without reinforcement have been built at Lindenwood and
Cheltenham, Mo., and elsewhere on the theory that under the
c6nditions on this road a saving of 50 per cent, in concrete is
necessary to warrant the use of reinforcement and this can not
be done under the existing conditions. The concrete in the
bridges referred to cost |4.60 and |4.80 a cubic yard, respec-
tively, in place.

MISCELLANEOUS USES.

The street railway company in Minneapolis, Minn., made a
novel use of concrete in reconstructing some of its lines and
making the rails continuous by welding the joints. A longi-
tudinal beam of concrete was constructed, to which the rails
were spiked before the cement was set, thus making a con-
tinuous support to the rails, and a tight fastening for them.

THE USES OF CEMENT. 167

Concrete is frequently used as a foundation for the wooden
ties of street railroads, but in this case the ties are displaced
entirely. The usual concrete foundation for an asphalt street
was laid over the street, and the pavement completed by
laying the asphalt. Constructions of slightly different de-
signs have been adopted with greater or less success in other
cities, for example, Scranton, Pa., and Indianapolis, Ind.

Within the past ten years there have been several in-
stances of making solid foundations in gravel and sand, espe-
cially if under water, by injecting a thin cement grout by
means of tubes run down to the stratum which it is desired
to solidify. Open gravel can be very successfully treated in
this way. Fine sand will refuse the grout if already filled
with water.

For such small uses as cistern tops, horse blocks, steps,
caps and sills, plastering cisterns, basins and manholes,
Portland cement is the best material. Specifications for
sidewalk mixtures are applicable to most of these uses, with
slight modifications.

Tiles made of 100 parts by weight of damp sawdust, 240 parts
Portland cement and 48 parts water can be nailed without
cracking. The sifted sawdust should be thoroughly wet and
allowed to stand 24 hours before mixing and the tiles should
be frequently sprinkled while setting for successful results.

Concrete coal bunkers with concrete chutes are used at the
Dumferline Power station, Scotland.

Fences and ornamental gateways in cement concrete are
very successful.

Cement can be used for statuary, fountains, monuments,
where the color is satisfactory, and js frequently very
effective.

Concrete, without any reinforcement, was used. as long ago
as 1800 in Germany for a factory chimney about 160 feet high.

There are several forms of burial caskets in concrete, mono-
lithic and in slabs which fit together so as to be locked and
water-tight. One French form uses steel rods as reinforcement.

The ornamental work for buildings is very easily and cheaply
made of concrete. Care is needed to make good mixtures
especially for the faces and to cure the blocks thoroughly and

168 HANDBOOK FOR CEMENT USERS.

under uniform conditions of temperature and moisture that
there mar be no. crazing or hair cracks. One contractor re-
ports excellent results using one part of Portland cement and
six parts of gravel for the body of the block and one part of
Portland cement of exceptionally uniform color to two parts
of ground Bedford stone chips for the face, at cost about one-

ORNAMENTAL CEMENT WORK ON A CUBAN RESIDENCE

half that of stone for plain work and about one-quarter for
molded work. Porch piers, columns, and caps, newel posts,
balustrades, vases, seats, fences, horse blocks, hitching posts,
fountains, including elaborate designs of molded work and fig-
ures make a list illustrative of the many ornamental and use-
ful objects which can be constructed of concrete.

The cements required are usually those of lightest color, and
in some works it is necessary that they be non-stainin'g. Uni-
formity of color is most essential.

For the faces of stones fine white sand is usually demanded.
One good mixture is 1 part cement to 1% parts ground Bed-
ford chips and % part of fine white sand. An excellent granite
face is given by hard crushed granite (such as granite boul-
ders), of pea size and smaller.

THE USES OF CEMENT.

169

The molds should be somewhat porous to absorb any excess
of water in the mortar. Wooden molds are good if the patterns
are not too delicate and the surface need not be too fine. Iron

CONCRETE FACING AND ORNAMENTAL WORK ON GERMAN RESIDENCES.

molds are not sufficiently porous. Plaster molds are excellent,
but require expert men to mold the patterns in clay. This
class of work is best made with wet mixture, and the porous
mold prevents the formation of air holes on the surface and

170 HANDBOOK FOR CEMENT USERS.

trouble with excess of water when curing. The stones are also
less porous when finally set. The wet processes of making
concrete blocks and. artificial stone in sand molds, elsewhere
described, are applicable. Trowel finish on artificial stone is
not usually advisable. It brings neat cement to the surface
and hair cracks are almost certain to appear, even under the
most careful manipulation in curing.

The Greek amphitheatre at the University of California, is
built of concrete, three-fourths in excavation and one-fourth
above th'e original ground surface. A central circle 50 feet 8
inches in diameter has about it on one semi-circle in order, a
tier of 12 steps 3 feet broad and 5 inches rise, a 9-foot aisle, a
wall 5 feet high and 10 inches thick with a bench on its front,
and 19 rows of steps with 30-inch tread and 18-inch rise form-
ing seats, with radial aisles, having steps of 1,5-inch tread and
9-inch rise, and a wall 2 feet high and 10 inches thick. On the
other side of the central circle is an 18-foot walk from the side
entrances sloping down from the base of the seats to the central
circle; the stage, 134 feet long, about 50 feet wide and about 5
feet above the central circle ; and the wall with its classic orna-
mentation and end pylons, molded in place, surrounding the
stage on three sides. All is of concrete, some steel reinforce-
ment being used where it was appropriate, with the exception
of the central circle, which is of disintegrated granite on a foot
of loose rock, well underdrained. The effects of contraction of
of concrete and local settlements are concentrated by No. 30
sheet steel plates placed vertically in the steps every 8 or 10
feet, and in the panels of the wall back of the stage. This
construction has prevented any temperature or settlement
cracks.

METHODS OF REINFORCING CONCRETE.

There has been a very rapid development in the use of rein-
forcement for concrete in structures in this country since the
last edition of this book was published. The study of the action
of such structures has proceeded with great thoroughness and
some approach has been made toward the formulation of meth-
ods of computation of strength and dimensions of structures
of various sorts, with strong indications that formulae will
shortly become as definite as those for steel construction, pro-

THE USES OF CEMENT. 171

vided methods of construction can be given similar uniformity.
It is not the purpose of this book to give methods of calcula
tion and design, but simply to give some description of the
various systems which have been proven to have considerable
value and some examples of actual construction. The various
systems and modifications of systems which have received
names are aranged in alphabetical order. Following them are
mentioned other methods of using reinforcement which have not
received specific names and structures containing one or more
of the systems are described. It will be noted that many of the
systems differ very slightly, often only in the details of con-
nections of rods or bars, and that there are many designs in
use w^hich have never received specific names.

In the Ambrosius system the principal reinforcing bars
have projections to carry a wire cloth which furnishes the
necessary transverse tensile strength.

The Armored Concrete Construction Company (English)
construct piles with angle irons in corners, connected by straps
at intervals and wire spring diaphragms alternating

The IBone reinforcement for walls, especially retaining walls,
consists of steel bents of angles and plates embedded in the
back part of the wall at fixed distances apart and tied back
into the greatly widened foundation of the wall by angle irons
with brackets attached to prevent pulling them out of the
concrete. A similar anchor extends toward the front of the
wall when deemed necessary. The ends of these anchors are con-
nected by an angle bar running the length of the wall and the
bottoms of the bents are connected together by an angle bar.
Mr. Bone recently made a comparison of bids for a plain con-
crete wall for the same locality and the same work, showing
that the plain concrete wall woulld cost $21.20 a linear foot
as compared with a cost of $13 for a reinforced concrete wall.

The Bonna (French) system uses steel 'cross-shaped sections
for reinforcement, the relative strength of one arm of the cross
having considerable variation for various situations. It is
specially used in making pipes, the reinforcement being ar-
ranged with a number of longitudinal bars and a spiral encir-
cling them, the longitudinal bars being notched to receive the
spirals. The Columbian fire-proofing system uses a double
cross section devised by Bonna.

172 HANDBOOK FOR CEMENT USERS.

The Bordenave (French) system uses small steel I-beams
and round rods. It has been used in floors, reservoir coverings
and pipes, the bars being tied with wires at their intersections.
For pipes machinery is used for winding the helical rod around
the longitudinals (placed outside if the pressure is from the
outside) and the coil is then drawn out along the pipe to the
spacing desired.

The Boussiron and Garric (French) system consists of series
of rods on the tension lines in the concrete, and on diagonals
in deep beams. Floor slabs have two sets of rods at right an-
gles. Columns have vertical rods tied together with hoops of
flat bars. The system is also used in circular tanks above
ground.

The Bramigk (German) system for floors uses bars near the
lower surface and concrete or earthenware pipes parallel with
them about which the concrete is laid, thus making a hollow
floor with the steel reinforcement in one direction on the ten-
sion side.

The Buckeye floor construction consists of steel floor beams
and joists supporting continuous corrugated iron plate arches
of a few inches span with concrete filling above.

The Busso system is similar to the Boussiron in principle.

The Chassin system is similar in principle to the Boussiron.

The Chaudy (French) system has two sets of longitudinal
bars near top and bottom of beam, which are rigidly connected
by rods, closed hoops, or flat bars riveted to them. A series of
beams laid close together, but monolithic as to laying of con-
crete, forms a floor. Walls, stairways, tanks and aqueducts
are also constructed in this system. It also uses transverse
rods bent in rectangles about the longitudinal rods, which are
near the lower surface, the loops or waves thus formed extend-
ing along the upper surface of the slab until they reach the next
longitudinal rod when they are bent back to enclose it.

A similar system of the "Societe des Chaux et Ciments de
Creches" (French) uses a small rod at the top of a beam to
keep in place the rods used for connecting the lower rod in the
beam and the floor slabs on the top of the beam.

The Chicago system of Theo. Kandeler uses steel floor joists
and transverse channels supporting sheet iron arches on which

THE USES OF CEMENT. 173

concrete is deposited, steel bars embedded in the concrete sup-
porting wooden strips, also embedded, which in turn carry the
wooden floor. The Roebling ceiling is attached to the bottom
of the floor joists.

The Clinton Wire Cloth Company supplies a wire fabric
which has the intersecting wires welded together by electricity
and is used for all purposes for which wire cloth or intersecting
rods are adapted.

The Coignet (French) system in floors uses two sets of rods
at right angles near the lower surface with sometimes a similar
system of lighter rods near the upper surface, the two systems
being connected with stirrups. Beams have rods near top and
bottom of section connected with stirrups or a rod running
between the upper and lower rod in zigzag and tied to these
rods at the points of contact with them, thus forming a sort
of triangular system of girder bracing. Columns, foundations,
walls, retaining walls, stairways, pipes, elevated tanks, etc.,
are made with modifications of the system. This was the ear-
iest system suggested, 1888, but was not put in practice so early
as some others. For pipes hoops are made with the ends
hooked together, a rod passing through all the hooks to hold
them together. The longitudinal rods are tied occasionally to
the hoops, and additional diagonal rods or wires are used when
deemed necessary.

The Columbian fireproofiing system uses rolled beams em-
bedded in concrete with Bonna double cross sections as rein-
forcement for floor slabs, also embedded in the concrete and
attached to the top flanges of the floor beams by flat iron
stirrups over the flange and slotted .to receive the ends of the
cross bars. The bottom flanges of the beams are covered with
concrete held in place by hoop iron clips hanging from the lower
flanges.

Considere (French) has developed a number of applications
of reinforcement and the system of hooped columns of concrete
may properly be given his name, though it is used in one form
or another in several systems.

The Cottancin (French) system was patented in 1889. It
uses a woven net work which does not require fastening of the
wires or bars together at their intersections. Floor slabs are

174 HANDBOOK FOR CEMENT USERS.

supported often enough to be thin and the net work is embedded
near the center. The stiffeners are vertical slabs of similar con-
struction with the webs interwoven with that of the horizontal
floor slab by means of the projecting ends of the wires of the
stiffener. Thin partition walls, roofs, domes, pipes, rectangular
and circular tanks are also constructed according to this
system.

The Coularou (French) system uses rods near the lower edge
of beam and also rods running from ends toward center of
span near top, bending down on 45 degree diagonal to bottom
near center of span, with diagonals connecting the two series
of rods. Floors, columns, roofs and walls differ only in details
from the preceding system.

The Cunimings system uses bars of varying lengths bent near
ends to diagonal for resisting shear and looped at ends.

The Czarnikow system does not connect the reinforcing flat
bars with each other except by means of the embedding con-
crete.

The Degon (French) system has two sets of rods near top
and bottom of beam connected by wire wound round and also
projecting up between in the general form of a letter W closed
by extending each wire across the top. They may then be ex-
tended through the intervening floor slab to the next beam.
The floor slabs have these rods near the lower surface connected
by transverse wires of sinuous form embedded in the concrete,
and without the longitudinal rods near the upper surface.
Reinforcement of walls and posts is modified in position to
conform to the change in lines of stress but follows the same
system of closely connecting all the lines of reinforcing to-
gether, so that they are capable of considerable resistance to
the stresses without the aid of the concrete. For pipes bent
rods of form above described are used for the circular reinforce-
ment and the longitudinal rods are placed in the outer bends
and tied there.

The DeMan bars for reinforcing are rolled in wave-like form.
The bars are square in cross section increasing and decreasing
in dimensions with the undulations.

The Demay (French) system uses flat bars very thoroughly
connected together by interlacing bars of smaller cross section.

THE USES OF CEMENT. 175

Columns are reinforced with round bars which are partly in-
terlaced with the bars in the beams above and below them
and partly carried to the columns above and below.

The Donath (German) system us^s steel floor joists with
small T-bars transversely, which are tied together by hoop i-on
perpendiculars and diagonals, bolted to the T-bars. S-shaped
bars are a special form peculiar to this system. The space b >-
tween beams is then filled with concrete, a wire netting below
carrying the ceiling of the room below. Molded blocks fitting
the S-shaped bars are sometimes used instead of the mono-
lithic concrete, these blocks being hollow. Partition walls aie
also made of these hollow blocks with as much reinforcement
as circumstances require.

Duesing uses flat bars twisted while hot so that the convolu-
tions prevent the pulling out of the bars from the concrete.

The Expanded Metal system has for its principal character-
istic a net work formed in a special way by cutting slits in a
sheet of steel and then pulling it out sidewise so as to produce
a net work with vertical flat ribs and diamond shaped openings
with the metal at the intersections solid because uncut. This
metal can be used for any purpose for which wire cloth and sys-
tems of intersecting rods are used, apparently with some ad-
vantages of either strength, stiffness or cheapness over most of
them. Kods, bars, straps, etc., are used as they seem to be
needed as adjuncts.

The Fairbairn system for spanning wall openings has
straight rods for the extrados and rods curved to fit the arched
intrados, all having turns at ends to give hold on the concrete
in the wall.

The Ferroinclave system uses a sheet steel corrugated in dove-
tail shape and used like wire cloth.

The Gesche system for walls is like the Huguet and permits
making in advance and setting in place.

The Gruening system is similar to the Fairbairn.

The Habrich system uses twisted flat bars in various combina-
tions with floor beams in making beams, floor slabs and floor
arches.

The system Harel de la Noe uses steel rolled shapes and is
self-supporting.

176 HANDBOOK FOR CEMENT USERS.

The Helm system uses independent flat bars embedded in the
concrete.

The Hennebique system was brought out in 1892, the inventor
having constructed reinforced concrete floors as early as 1879.
For floors rods are used, one set straight and another set bent
up near the points of support to pass over them, placed alter-
nately. Sometimes the rods are used in both directions across
a slab. Near the points of support stirrups may be set passing
under the rods and up into the concrete, being turned over at
upper ends to give a hold on the concrete. Eeams have simi-
lar construction modified to suit the work. Foundations, col-
umns, stairways, arches, dock walls, piles, sheet piles,
etc., are constructed on similar principles, the straight and
bent rods taking the tension and the stirrups giving resistance
to shear. For arches the stirrups take the form of rods hooked
about rods bearing on the main rods near top and bottom of
arch rib.

The Holzer (German) system uses I-beams.

The Huguet system for walls uses vertical round baiN inter-
laced with network. The pieces are made in factory and set in
place.

The Hyatt system uses flat bars with holes punched in them
through which are passed transverse wires. Floor slabs are
the principal place of application, but beams have also been con-
structed with this form of reinforcement on the tension side.

The International system of floor construction uses wire net-
ting supplemented by steel-wire ropes in reinforcing floor s'abs
and girders. The cables in floor slabs are anchored to the walls
at both ends and are carried over the girders, sagging in middle
of spans to lower side of floor slab, and the wire netting is on
top of the cables.

The Johnson bar for use in reinforcing is a corrugated bar,
rectangular in cross section and with rectangular projections
on all four sides, alternating in position on adjacent sides.

The Kahn system uses diamond or other shaped cross sections
of reinforcing bars which permit of shearing projecting wings
for given lengths along the bar, these sheared portions being
then bent to an angle of about 45 degrees with the bar, thus
causing the shear members to be rigidly connected with the

THE USES OF CEMENT. 177

tension members of the reinforcement. The shear bars may be
flat bars with one end riveted to the plate and the bar then bent
through 135 degrees to the position for use.

The Kindle system was one of the early American systems.
The transverse beams of a floor system were formed of hollow
tiles reinforced with flat iron straps suspended from the top
flanges of the floor beams with transverse rods joining them to
the tiles.

The Klett (German) system for floors has flat iron bars, so ne
extending from floor beam to floor beam and bent ro;md tie
upper flanges, or projecting into the next span, the bai's being
depressed in the center of the span to the tension side. Trans-
verse flat or angle iron bars are used as needed, attached to the
main bars at intersections.

The Koenen (German) system uses round bars hooked over
the upper flanges of floor beams or anchored in walls, ani de-
pressed to bottom surface at middle of span. Concrete is
filled in about floor beams, thus showing flat arch form in ceil-
ing of room below. This system is used in this country for
spans up to about 20 feet.

Kuhne's sheet metal is slit in the game manner as expanded
metal, but alternate points of uncut metal are pres-ed up so
as to form a reticulation on two parallel planes with diagonal
bur connections between them. It can be used like other wire
cloth and has the special characteristic of the double i-Mnfoiv-
ing giving it properly the name of trussed metal lath.

Lefort's system is like that of Boussiron and he is said to
have devised it. The reinforcing rods are not connected by
metal. It uses parallel pairs of roils in two horizontal planes,
symmetrical about an axis.

The system of Lilienthal is very simple, with continuous
wires or bars in floor slabs extending over and supported by the
floor beams, whose vertical reinforcing bars are attached to
the floor-reinforcing wires.

The Locher (German) system for beams uses layers of flat
bars horizontal at center and near lower surface of beam and
bent up toward the top surface at different distances from the
center in curved form, thus carrying tension and shear in a
beam supported at both ends.

178 HANDBOOK FOR CEMENT USERS.

The Lock- Woven Steel Fabric is a steel wire mesh locked at
the intersections in the process of manufacture and u<(d like
other wire mesh reinforcement.

The Luipold system is very similar to the Hennebique.

The Luten system of arch construction uses round rods in
the arch ring, following the lines of tensile stress as nearly as
convenient. Its principal feature is the tie bars under the
bed of the stream to which the stresses in the arch are trans-
mitted, thus reducing materially the weight of abutments.
These rods are embedded in a concrete paving for the bottom of
the stream under the arch.

The Luther system is like the Huguet and is made in advance
and set in place.

The Maciachini (Italian) system utilizes the principle of
hooping, using four rods bent backward and forward for the
four sides of a beam, the bottom and side rods being threaded
together before they are put in place after the concrete has
been placed for the bottom section of the beam. After placing
the concrete with whatever other reinforcement is necessary,
the upper rod is bent and threaded into place and the final
layer of concrete is deposited.

The Matrai (Hungarian) system uses steel wires or cables
sufficient to carry the entire load under tension, the concrete
being used simply as filling and to distribute the weight. For
floors diagonal wires are run between the main and the second-
ary beams as well as wires parallel to each set of beams, thus
forming a close network of suspension wires about which the
concrete is deposited. The wires in columns form parabolic
curves, are wound about a ring at the top and hooked into an-
chor rods at the bottom. Walls have combinations of I-bars
and rods.

The McCarthy bridge floor uses two sets of wires, one run-
ning horizontally from floor beam to floor beam and the other
in suspension form passing continuously over the floor beams
from end to center of the bridge, where an expansion joint for
the floor is located. Each group of wires of the two sets is
encased separately in concrete and these ribs below are joined
by the concrete floor foundation above. Thus the wires carry
the tension and useless concrete is omitted below, and the con-

THE USES OF CEMENT.

crete in the upper surface carries the compression stresses.

The Melan (Austrian) system for arched floors and bridges
uses I-beams or other rolled shapes, bent to the arch form and
filled around with concrete. A tie rod is used if necessary.
In long spans the beams become built-up girders.

The Metropolitan fireproofiing system uses I-beams with
transverse two-wire cables stretched over them, on which are
laid round rods at the center of the span to secure uniform
position. The concrete is laid about this reinforcement. Ends
of cables are hooked over flanges of beams or anchored in wall.

The Moeller (German) system for floors and beams uses flat
bars in tension side of beams to which are attached short
pieces of angle iron to resist pulling out. Floors are reinforced
with I-beams in the concrete.

The Moreland system is like the Falrbairn, but uses bent
rods in the reinforcement of the arch.

The Monier (French) system was perhaps the earliest general
method of application of reinforcement to concrete. It is sim-
ply two series of wires or rods at right angles, tied together
at the intersections. Floor slabs, ceilings, arches, beams, col-
umns, partition walls, pipes, sewers, tanks, piles and all sorts
of ornamental and useful objects have been made on this systein
and many of those in this list are merely modifications in ap-
plication or in form or material for avoidance of patent, which
has now expired, or for some improvement in detail. Monier
cylinders have been used to surround and protect wooden piles
in sea water. -^

The Mueller, Marx & Company's (German) system uses for
floors upright flat bars extending from joist to joist, tied to-
gether with similar zigzag bars secured by iron clips. For long
spans the bars may take the suspension form and are firmly at-
tached to floor beams or anchored in walls. Stairs are self-
supporting if built on this principle. A notable application of
this system is to bridge abutments having only a screen wall on
the face and a concrete floor behind, supported on one or more
reinforced concrete walls running back into the fill of the
approach.

The Multiplex steel plate floor system uses a steel plate cor-
rugated with alternately two waves near an upper plane and

180 HANDBOOK FOR CEMENT USERS.

two near a lower plane, the lower corrugations resting on the
floor beams, and the space above the plate being filled with cin-
der concrete.

The Neville system uses two sets of reinforcement in beams
and connects the two sets by diagonal ties or braces, thus giv-
ing them some mutual support.

The Parmley system for sewers, conduits and arches uses
bars around the arch with bent ends to engage the concrete, so
placed as to resist the tension in the haunches and crown of the
arch.

The Pavin de Lafarge (French) system for beams uses two
rods at top and bottom tied together by zigzag flat bars tied to
the rods, or round wires or rods wound once around each rod
at each turn. Floors and ceilings are similar to Monier con-
structions, floor slabs often being made on the ground and laid
in place after the rest of the construction is finished. For
pipes longitudinal rods are used wound spirally with small
wire or hooped at intervals if section of reinforcing bar is heav-
ier. Reservoir covers and tanks are readily constructed on
this system.

, The Picq system is another analogous to the Hennebique,
using rods near lower surface of slab and bent rods which are
near upper surface at points of support and near lower surface
in middle of span.

Piketty (French) prefers round rods, gradually increases
the angle of his transverse reinforcement for beams, from verti-
cal at the center to 30 degrees with the vertical near the points
of support, inserts his reinforcing rods where they are needed
to carry tension.

Rabitz (German) uses wire network with diamond or hex-
agonal meshes in rolls. A specialty in this system is the pro-
tection of reservoir and. canal slopes with reinforced concrete
slabs.

The Ransome system uses square bars twisted cold with a
definite angle to the twisted surfaces. Forms of construction
are similar to those in other systems.

The Rapp floor has inverted T-bars, supported on the flanges
of floor beams, which carry on their flanges brick or tile upon

THE USES OF CEMENT. 181

which a layer of concrete is deposited. For arch form of ceil-
ing the T-bars are bent to the form desired.

Rechtem, Vernig and Dopking (Dutch) piles have I-beams
framed together and embedded in concrete.

The Renton system of fire-proof floors consists of a flat cinder
concrete arch reinforced with barbed wire, there being various
designs to meet conditions as to strength, kind of flooring ma-
terial, depth and weight of floor required, etc.

The Roebling fireproofing system uses the ordinary floor
beams and built steel columns, protecting them from fire by con-
crete surrounded by woven wire on which concrete plaster is
laid. Floors, when arched, are stiffened by steel rods woven
into the wire cloth, which is arched as a support for the con-
crete in laying. The ceiling is of reinforced wire cloth sup-
ported from the crown of the arch, on which the plaster is laid.
For flat floors, flat reinforcing bars on edge are used, clamped
to the supporting beams and connected by flat bar separators.
The concrete is preferably made with cinders or other fireproof
material. There are several modifications of these central ideas,
the intention being always to protect the steel from the action
of fire.

The Roessler system uses flat bars which have no metallic
connection with each other.

The Rossi system uses wires or bars bent in sinusoidal form.

The Schlueter (German) system uses intersecting bars tied
together like the Monier system, except that the bars run
diagonally.

The Siegwart (Swiss) system for floors uses hollow beams
which are made in a factory and when cured they are taken to
the building and laid in place side by side and grouted with
cement. The beams are hollow and reinforced with rods and
stirrups as the spans and loads may require. Deeper beams
are constructed as supports for the ends of floor slabs when
spans are long enough to require them.

The Staff system uses flat bars stamped with circular pro-
jections about and into which the concrete is deposited.

The Stellet system is similar to the Coignet and depends
largely upon the diagonal bracing between the main reinforcing
rods.

182 HANDBOOK FOR CEMENT USERS.

The Stolte (German) system uses hollow concrete blocks
which have longitudinal hollows between which upright flat
bars are embedded. The blocks are joined with cement mortar
and the floor slabs thus formed are supported on steel or timber
floor beams.

The Thacher system uses flat bars in pairs, one bar near ex-
trados and one near intrados, each bar having projections for
increasing their hold on the cement. The bars are bent in arch
form and the system is similar in intent and application to the
Melan system, but there is no connection except the concrete
between the bars of a pair. Mr. Thacher also has a round bar
which is flattened out alternately on planes at right angles
to each other, which is of more general use than the bar flrst
mentioned.

The Turner system uses in columns a grill of vertical rods
banded at intervals by strong riveted hoops with one of the
rods bent outward into each beam resting on its top, the whole
wrapped or hooped with netting. The column thus acts as a
whole and is thoroughly bonded to the adjacent beams. In the
construction of beams he makes them continuous over their
points of support, thus requiring the reinforcing metal to
change position from the lower side of the beam in the center
of the span to the upper side over the supports, and supplying
the proper resistance to shear in the length of beam in which
this change in location takes place. The centering to support,
forms is reduced to a minimum and on many spans is omitted
altogether for beam construction.

The Yallerie and Simon (French) system as applied to reser-
voirs consists of rods bent to the circular form of the reservoir
and attached at proper distances apart to temporary uprights
until the vertical rods could be put in and tied to the circular
rods, and the concrete could be placed.

The de Valliere (French) system uses a rod on which is
threaded a wire bent back and forth, each loop extending a
given distance from the rod and on its return forming an eye
for the rod to pass through. The rod being threaded into these
loops, they are spread out along the rod to any spacing desired.
Floor slabs have series of these rods and wires, and floor beams
may have one, two or more as size and loads require.

THE USES OF CEMENT. 183

The Veyhe system is similar to the Fairbairn.

The Viennot system is similar to the Busso and Boussiron.

The Visintini (Swiss) system is one of lattice girder con-
struction, being in appearance a system of girders on the same
principle as a steel lattice girder. The reinforcing bars are
found on all the lines of possible tension. The members of a
structure are made in a factory and laid in position after the
concrete has thoroughly set. The latticed floor sections are
laid side by side and grouted together. When the length of
spans requires, larger floor beams of similar construction are
put in as supports for the floor sections. Stairways, columns,
walls and partitions are readily made on this system.

The Von Emperger reinforced arch uses instead of the arch
ribs of the Melan system bars of metal embedded in the con-
crete near extrados and intrados and parallel thereto, and con-
nected by bars, this forming a less rigid truss system.

The Walser-Gerard (Swiss) system uses two sets of rods in
beams and floors, one set near upper surface and one near the
lower and a transverse wire entering from an adjoining slab,
passing round in succession rods in the upper and lower sets
alternately and on into the next slab. This wire may run
vertically between sets or on a diagonal to aid in taking care
of shear. This interlacing may be run on diagonals and verti-
cals over the whole length of the beam, the verticals being
spaced to correspond with the shear stresses.

The Wayss system is a modification of the Hennebique,
changing the form of flexure of the bars near the points of
support.

The Weber system for chimneys uses T-bars connected at the
intersections by special forms of sheet metal clamps.

The Weyler system uses light steel strips with large circular
holes stamped in them and bent to show in cross section of slab
the I-form. They extend almost the full depth of the floor slab.

The Williams (English) system for piles uses an I-beam,
sharpened at one end by cutting away the web and forging the
flanges together to a point, flat steel tie bars fastened near ends
of pile and trussed out to serve as stiffeners under heavy loads,
and hoops of flat steel to strengthen the concrete against exces-
sive compression. Piles are closely bound to reinforced con-

184 HANDBOOK FOR CEMENT USERS.

crete beams serving as caps. In floors are used longitudinal
I-beams with flat bars bent over and under them transversely
showing lenticular form in view of cross section of floor. In
beams of long span the reinforcement is of angle irons near top
and bottom of beam, connected by diagonal flat bars riveted to
them.

Wilson's system uses flat bars suspended from the top flange
of the floor beams by hooking around them, the bar in the cen-
ter of the floor slab span being near. the lower surface, and
near the top at the points of support.

The Wuensch (Hungarian) system uses T-shaped beams,
the flat floor slabs resting on the upper flanges of floor beams
and the arched lower section resting on their lower flanges, the
T-bars being riveted thereto. For arches angles may be used
and the entire space between arch ring and horizontal extrados
filled with concrete. Mr. A. W. Buel has modified this by mak-
ing both extrados and intrados curved and adding longitudinal
angles connecting the ribs, with diagonal bars connecting the
upper and lower ribs.

REINFORCED CONCRETE DAMS.

The Ambursen and Sayles method of building reinforced
concrete dams uses an inclined concrete slab continuous from
pier to pier, reinforced with Thacher bars and expanded metal,
supported on solid concrete buttresses about 12 inches thick
and 6 feet apart. It is a gravity dam, although a large amount
of concrete is saved in the spaces between the buttresses under-
neath the concrete slab. Several of these dams have been con-
structed in the last two years.

CONCRETE GRAND STANDS.

Washington University built a grand stand for its athletic
field which was in use by the St. Louis Exposition in 1904, of
concrete with steel reinforcement in the seats and in the front
and rear walls, at a cost of $32,000.

The Harvard Stadium is another notable example of this
application of reinforced concrete.

Perhaps the earliest structure of this sort is the grand stand
at the baseball park in Cincinnati, O., built according to the
Ransome svstem.

THE USES OF CEMENT. 185

CROSS TIES FOR RAILROADS.

There are now innumerable designs and patents for the appli-
cation of concrete, plain or combined with wood or steel, to
the manufacture of cross ties for railroad use. The longi-
tudinal beam for supporting the rail has been used to some ex-
tent for street railways, but is not sufficiently flexible for steam
or interurban railroad conditions. The Kimball tie has two
rectangular blocks of concrete, one for each rail, connected by
two channel bars. Hard wood blocks on top of the concrete
carry the rails. The Burbank tie is a solid concrete tie with a
special form of twisted steel plate embedded in it. These rep-
resent the principal classes of reinforced concrete ties.

CONCRETE PILES.

The Raymond concrete pile has a round steel bar in the axis
of the pile and three smaller bars equally spaced around the
circumference. The apparatus for forming these piles in place
is somewhat elaborate, but the piles are very rapidly con-
structed.

The Simplex concrete pile is reinforced with expanded metal
in cylindrical form. It is constructed in place, the previously
formed concrete head being driven to place by means of a steel
cylinder fitting it, into which the expanded metal cylinder is
slipped and the concrete is poured, the driving cylinder being
withdrawn as the concrete is filled in. For piles in water an
outer steel cylinder is slipped into place to form the outside of
the pile.

Many of the preceding systems of reinforcement can be ap-
plied to the construction of piles, as is stated in connection
with the mention of several of them.

FENCE POSTS.

The number of patents on reinforced fence posts is only ex-
ceeded by the number on hollow concrete blocks. Wooden rods
were first used and they were soon displaced by iron or steel,
including gas pipe, round, square, corrugated, or twisted rods
or wires, barbed wire and cables. The methods of fastening
the fence to the post are various also, including wooden plugs
or blocks as nailing pieces, various forms of clamps, eyes,
wrapping wires and staples. Some use simply holes in the

186

HANDBOOK FOR CEMENT USERS.

post through which bolts, staples or wires can be passed. All
these chances for variation give rise to many patents.

Posts are usually made of gravel, not too large in size. Many
of the natural mixtures of gravel and sand are nearly correct
and can be tested by trying the effect upon the percentage of
voids of adding sand to or subtracting it from the natural
mixture. The proportional amount of sand depends upon the

REINFORCED CONCRETE FENCE POSTS. SHOWING LINE, CORNER, STRAINING
AND ANCHOR POSTS AND SECTIONS.

variety in sizes of the gravel and that mixture should be used
which, when made into concrete and rammed in place will
give the smallest volume of concrete. An average proportion
of cement for good work is about 1 to 4 of the mixture of gravel
and sand. If there is too little sand the proportion of cement
must be increased. It may be necessary to increase it also if
there is too large a proportion of sand. The voids in the aggre-
gate must be filled by the cement and, except a small excess to
insure this, a larger proportion of cement is unnecessary.
An easy approximate way to find how much cement is needed
is to fill a box of known size with the gravel and then see what
volume of water can be added to the box without overflowing,
this will be the volume of cement to be used, adding about 10
per cent, if it is measured loose or if the mixing is not most
thoroughly done.

Molds for posts are usually made of wood, metal ends being
desirable. It is well to mold posts on a bed on which they can
remain until they are cured, and if they are moved away from

THE USES OF CEMENT. 187

the machine or place of molding for storage the pallets must be
stiff and unyielding and must be handled without shocks.
Many posts are weakened if not destroyed by breaks or shakes
in handling before the cement has fully set. Sometimes molds
are made in sections so that two to five posts can be made with
the same setting. The reinforcing wires must be carefully
placed so that the concrete can be thoroughly rammed, and the
placing of the fastening devices must be provided for in the
faces of the molds.

Posts should be thoroughly cured, being sprinkled at inter-
vals for some days. Posts are frequently used in three or four
weeks after making, but should be left to cure for three to six
months or more for the best results.

REINFORCED CONCRETE RESERVOIR COVERING.

The roof of the covered reservoir at Newton, Mass., is sup-
ported on brick piers 20 inches square, each panel being 11
feet 10% inches by 11 feet 8 inches.

The covering of the reservoir may be briefly described as a
monolithic floor of concrete, reinforced with ribbed steel bars,
and supported on the tops of 12-inch I-beams, the latter also
incased in concrete. The I-beams weigh 3iy 2 pounds per foot
and were cut long enough to span two of the 11-foot 8-inch
spaces and leave 14 inch for expansion. The specified loading
is 275 pounds per square foot, plus the weight of the flooring.
There was 150 pounds per square foot of loam placed on the
reservoir, and it was estimated that 125 pounds per square
foot would be equivalent to the maximum strain which might
come on the concrete due to any moving load such as a crowd
of people or teams passing over the reservoir. Such a load,
however, would be extremely unlikely to occupy a large portion
of the reservoir at any one time, so that it need only be used
in determining the strength of the concrete-steel filling between
the beams.

The flooring itself has a span of 11.9 feet, center to center
of the I-beam supports. It consists of 7 inches of Portland
cement concrete in which are embedded 3%-inch Columbian
bars spaced 22 inches apart and resting directly on the I-beams.
This is but a sample of many similar structures.

188 HANDBOOK FOR CEMENT USERS.

REINFORCED CONCRETE GIRDERS.

At Purfleet, England, is a reinforced concrete girder, having
a straight lower chord of 60 feet length, a curved upper chord,
giving a depth of girder of 6 feet at the center, and verticals
dividing the web into panels 5 feet long with clear open spaces
in each panel. The floor is also of reinforced concrete. The
following is a brief description of the girder :

The upper chord is 18 inches wide by 9 inches deep, and is
reinforced by eight 1%-inch round bars. Cross bars are in-
serted transversely at frequent intervals, and serve to check
any tendency of the concrete to bulge laterally when the load
comes on the bridge. The lower or tension chord is also stif-
fened by eight iyg-inch round bars, which are connected to-
gether by stirrups of No. 12 S. W. G. iron 2 inches wide. These
stirrups are placed at intervals of every 10 inches and add
much to the solidity of the compound chord. The verticals are
cross-shaped in plan, each arm of the cross being 7 inches long
by 5 inches thick. Vertical bars, having hooked ends which
lap over the main bars in the upper and lower chords, are used
to strengthen these verticals. To avoid delicate adjustments
these vertical stiffening bars are made in two parts, which, af-
ter putting in place, are securely bound together by iron wire.
Along the top and bottom edges of each panel opening strength
is afforded by two %-inch bars extending from end to end of
the girder. Iron reinforcing bars are carried round each cor-
ner of the panel opening and prevent any tendency of the con-
crete to crack or open at these corners under the shearing
stresses.

The bridge on the Wabash railroad over the main drive in
Forest Park, St. Louis, Mo., is a through plate girder, on ac-
count of the requirements of head room. The abutments are
hollow and are built of reinforced concrete. Curved orna-
mental wing walls are also of reinforced concrete. To conceal
the steel girders, ornamental concrete balustrades have been
constructed. They are supported on brackets from the main
plate girders and are fully reinforced with steel bars of. the
Johnson type.

A similar structure more elaborate and more extensive is
provided for the Kiver Avenue bridge in Indianapolis, under
construction. In this case the plate girders are located be-
tween the roadway and the sidewalks. The ornamental gir-

THE USES OF CEMENT. 189

ders form the outside girders supporting the sidewalks, but
are aided in their work by brackets from the main girders.
The specifications for these girders and for the reinforced con-
crete bridge floors will be found in the following chapter.

BRIDGE FLOORS.

The Wabash railway has adopted standard designs for rein-
forced concrete bridge floors. One design for through bridges
uses a reinforced concrete slab, 6 inches thick, supported on 15-
inch I-beams 18 inches apart. The concrete is carried up the
sides of the main gk-ders to form a trough in which to deposit
the ballast for the roadbed and keep it away from contact with
the steel. This floor may be located anywhere from the bot-
tom of the girder up. For deck bridges the concrete slab and

PIPE CULVERT WITH CONCRETE END WALL.

trough are on top of the main girders. The concrete used is
made in proportions of 1 part cement, 2 parts sand and 4 parts
of stone passing 1-inch mesh. Mortar concrete is 1 part ce-
ment and 3 parts coarse sand. Reinforcing bars are y 2 -inch.
The River Avenue bridge in Indianapolis, is designed with

190

HANDBOOK FOR CEMENT USERS.

DOUBLE CONDUCT OF NEWARK, N. J., WATER WORKS. SHOWING METHOD
OF REINFORCEMENT.

a reinforced concrete floor under roadway, steel railway tracks
and sidewalks, using corrugated bars and supplying troughs

SHOWING COMPLETED SECTION.

THE USES OF CEMENT.

191

for the ballast of the street railway tracks, the roadway pav-
ing being laid on the concrete directly.

CULVERTS FOR HIGHWAYS.

The Iowa State Highway Commission recommends in place
of pipe or wooden box culverts in highways rectangular rein-
forced concrete culverts. The reinforcement is woven or
barbed wire, or for longer spans is of steel bars, placed near the

CONDUIT OF INDIANAPOLIS, IND., WATER WORKS.

PANDED METAL.

REINFORCED WITH EX-

inner or tension side. The concrete bottom is first formed,
then the sides and top in plank forms and wing walls are con-
structed, especially on the up stream side. Care must be taken
to put the reinforcement in its proper place and to stretch it
so that it will do its full duty in aiding the concrete to carry
any tension which may come upon it.

REINFORCED CONCRETE CONDUITS AND SEWERS.

A reinforced concrete conduit has been constructed for an
irrigation system near San Antonio, Tex., which is under pres-
sure as an inverted syphon, and exemplifies the application of

192

HANDBOOK FOR CEMENT USERS.

this method of construction to conduits and sewers, whatever
system of reinforcement may be used.

REINFORCED CONCRETE BUILDINGS.

This is not the place for detailed descriptions of reinforced
concrete buildings. A few of the most notable examples may
be mentioned as indications of what has been done recently in

A REINFORCED CONCRETE BUILDING IN HALIFAX, N. J.

this line. The Ingalls building in Cincinnati, O., was the first
large building built on this system. The U. S. Naval Academy
at Annapolis, Md v has recently built a chapel of reinforced
concrete, one feature of which is a dome 09 feet in diameter,
with a cupola 110 feet above the main floor and a second
cupola 33 feet above, supporting a lantern 48 feet high. The

THE USES OF CEMENT. 193

plans for a reinforced concrete round house on the Canadian
Pacific railway look very much like those for a frame struc-
ture. The walls are plain concrete. The columns supporting
the roof are I-beams surrounded with expanded metal in con-
crete; roof braces being angle iron, encased in concrete. The
radial roof beams are I-beams enclosed in concrete. The trans-
verse roof beams are of concrete reinforced with rods and ex-
panded metal, and they support reinforced concrete roof slabs
of similar construction, using cinders to save weight.

ADHESION OF CONCRETE AND STEEL.

Professor Monsch, of Zurich, Switzerland, found the follow-
ing results of tests of the adhesion of cement and sand mortar
to steel rods, pulled out endwise :

Proportions Percentage Adhesion

Cement to Sand. of Water Lbs. per Sq. in.

1 1 10 654

1 2 15 697

1 3 569

1 4 540

Steel plates torn off by pull normal to the surface, plates
being 1% by 2% inches, and mortar in which they were set
being 31.2 pounds of cement to 1 cubic foot of sand, showed the
following results :

Time of Setting. Adhesion.

2 days 4 Ibs. per sq. inch.

7
12
17
24
27

9.5
13.5
16.2
18.5
18.8

Prof. Charles M. Spofford gives as the resistance of round
and square rods to pulling out of concrete of 1 part cement, 3
parts sand and 6 parts stone after one month, 219 to 274 pounds.
Flat bars had resistance of 42 to 226 pounds, and three special
forms had resistance of 138 to 508 pounds. Minimum embed-
ding of plain bars and rods was 24 inches and of special forms
12 inches, and in nearly every case the minimum resistance was
by rods with maximum length embedded in the concrete.

PRESERVATION OF STEEL IN CONCRETE.

A sidewalk around Bowling Green Park, in which were em-
bedded steel rods when the walk was laid in 1883, was recently
torn out in constructing the subway in lower Broadway, New

194 HANDBOOK FOR CEMENT USERS.

York City, and the rods were found to be in perfect condition.

The effect of concrete on iron was shown by embedding a
piece of galvanized iron in cement for six months. It was
then found that the galvanizing had all disappeared but the
iron was clean and bright.

Steel has rusted in concrete but the reason has usually been
found in too dry mixtures, especially of cinder concrete. The
true protection seems to be given by a thin film of cement on
the surface of the steel and this can not be insured unless the
mixture is wet enough to carry the cement to the steel and de-
posit it there. The cement apparently removes any rust which
it finds and prevents the formation of more. Some cements
have been successfully used as paints for the protection of
steel.

In- 1892 Wayss and Freytag, of Germany, built a water pipe
system of concrete reinforced with small wires. Eecent inves-
tigation of one pipe relaid in a new location showed the rein-
forcement to be still in perfect condition.

CONCRETE AS FIREPROOFING MATERIAL.

W. N. Hazen in a report on the Baltimore fire, says :
For the fire protection of steel the first requisite is conscien-
tious workmanship. Lime or its products have proved worth-
less. All stones in bulk spall and are not to be trusted. Broken
stone in concrete does not act the same as in a solid mass, as
evidenced by the floors of the United States Fidelity & Guar-
anty Co.'s building. Concrete stood the test remarkably well.
Terra cotta should be heavier, and under no consideration
should it be used in single thickness of %-inch. For vaults I
would recommend that a rich mixture of cement and sand be
used for inside and outside, with at least 5-inch terra cotta
blocks forming the core. That good, soft-burned brick will
stand fire is without question. Where facing brick is used, it
should be substantially bonded to the main wall, preferably
with brick.

John R. Freeman, in his report to the National Fire Under-
writers on the Baltimore fire, says the following:

The behavior of Portland cement compounds was in marked
contrast to the plaster of paris compounds. After studying
the Baltimore ruins I am very optimistic on the fire-resisting
quality of Portland cement construction. One great advan-
tage of Portland cement construction is that if you put it in
wet and soft, and almost semi-fluid, it will fill the voids and

THE USES OF CEMENT. 195 ,

leave no bad blow holes or cavities, even under mediocre care
and incompetent supervision. The careless workman thus has
less chance to get a poor joint than in brick work. With the
modern finely ground cements, if a slight excess of cement is
used above that theoretically needed to fill the voids between
the grains of sand, and, if the whole is thoroughly mixed, as
it can be easily by modern machines for this purpose, it ex-
cludes air and moisture and opportunity for corrosion. The
Portland cement concrete possesses far greater tensile strength
and shearing strength than the best brick work, and, in brief,
I believe that it presents a material for fire-resisting construc-
tion which is not excelled by anything yet known.

The Engineers' report to the Board of Fire Underwriters on
the Home building fire in Pittsburg, contains the following
paragraphs :

Owing to the fact that steel columns or girders or beams af-
ter being subjected to a long-continued fire will assume the
same temperature as fire-proofing, and owing to the fact, fur-
thermore, that the rate of expansion of the steel is much
greater than that of the fire-clay tile, destructive movements
are permitted which, as shown in this experience, will result
in considerable damage, and which damage will increase in di-
rect proportion to the height of the building.

In view of these important developments, it is our opinion
that important structures of this class should have a radically
different method of fire-proofing. The fire-proofing should be
in itself strong and able to resist severe shocks, and should, if
possible, be able to prevent the expansion of the steel work.

There seems to be but one material which is known that
could be utilized to accomplish these results, and that is first-
class concrete. The fire-resisting qualities of properly made
concrete have been amply proven to be equal to, if not better
than, fire-clay tile, as shown by the series of tests carried on
by the building department of the city of New York,

From the experience gained in street railway construction
in laying continuous rails, it is to a large degree possible to
prevent the metal from expanding. In street railway work
this has been accomplished merely by the adhesion of the pave-
ment to the side of the rails. In building construction the
same results could be obtained by encasing the columns and
girders with concrete placed directly against the steel work.
The adhesion of the concrete would to a large degree prevent
unequal expansion of the concrete and steeL The floor arches
should also be constructed of concrete, but of sufficient depth
to be able to resist lateral forces. With the prevention of in-
jurious expansion and the protection of columns with mater-

196 HANDBOOK FOR CEMENT USERS.

ials that can stand severe shocks of any nature whatever, the
modern steel frame constructed building would be more thor-
oughly protected against fire.

Both Siegwart and Visintini reinforced concrete beams are
fireproof. The Siegwart beams, which were tested in New York
city in August, 1904, withstood a fire of 1,800 degrees F. all
right.

The Visintini beams stood fire tests at the London Exposi-
tion fire in 1903, and a new test, which was made in the au-
tumn of 1904, in Trieste, showed the best results for the pro-
tection of the iron against the fire, although the concrete pro-
tecting the steel bars is only %-inch thick. The test w T as car-
ried out on two girders, each 10 inches high, 8 inches wide, and
a length of about 17 feet; between the two beams was sup-
ported one Monier slab, 1% inches thick and about 4 feet wide.
These two supports, attached to the beams, were I 1 /? inches
high and 1% inches wide. The clear span of the girders was
about 16 feet. The floor had a dead load of 32 pounds per
square foot, and was loaded with 2,000 pounds. The fire,
which was made to test this floor, lasted half an hour, and was
of a temperature of about 2,000 degrees F. It was extin-
guished by water, then the floor was allowed to cool off and was
loaded with 2,620 pounds, which is nearly five times the safe
load. -The girder showed not the slightest cracks only a de-
flection of about % inch, and broke down under a load of
2,800 pounds. The beams had an age of only a few days.

A floor made of steel beams, 5-inch ribbed bars of the
Columbian system, spaced 2 feet apart and embedded in 8%
inches of concrete, was recently subjected to severe tests to
show the value of concrete as a fireproofing. The main body
of the concrete was made in proportions of 1 part Portland
cement, 2y 2 parts sand and 5 parts ' broken stone, and its
under side \vas veneered with 2 inches of cinder concrete.
After a test loading of 1,000 pounds a square foot, the floor
was subjected to a temperature of about 1,700 degrees by
fire for 2 1 / 4 hours. Water was applied from a fire stream, the
fire repeated for 38 minutes and water again applied. The
floor was again loaded with 1,650 pounds a square foot. The
result was a deflection of 1% inches, 15-16 inch of which was

THE USES OF CEMENT. 197

due to the fire, a few cracks in the ceiling, and the washing
awav of some of the cinder concrete by the fire stream, in one
case to a depth of % inch. The test of the fireproofing and
floor was highly satisfactory.

Tests of concrete blocks at Oklahoma City, Okla., and their
successful resistance to fires in Estherville, Iowa, and Carbon,
Ind., are additional evidence of the fire-resisting qualities of
concrete.

The tests in progress at the fire testing station of Columbia
University, one or two of which have been published, are
finding additional valuable evidence on this subject. The first
of these tests the results of which were published, was made
in a test building, the roof of which was built as a concrete
floor reinforced with Kahn bars. The stone used was trap rock.
The floor stood a temperature averaging 1,200 degrees F. for
four hours, with very little injury except pitting of the surface
of the concrete ceiling where the stream of water used in ex-
tinguishing the fire struck it, a few small cracks and a slight
increase in deflection under the load of 150 pounds per square
foot which the floor carried. The test was eminently success-
ful and the method of construction and the materials were ap-
proved in New York city.

FACING OF CONCRETE WORK.

Concrete which is deposited in molds takes any imperfec-
tions of surface which the molds may have. It is necessary,
therefore, to have the molds as perfect in form and finish as
the concrete is expected to be. Even the grain of the wood
of a form is shown in a fine grained cement surface. If the
timber is used for forms for smooth concrete work it must be
planed perfectly smooth and must be clear and as straight
grained as possible. The planks must be joined in such man-
ner that the expansion of the timber when moisture is ab-
sorbed from the concrete will not break the continuity of the
surface, and they must be laid together so that adjacent planks
will form an unbroken surface. One edge of a plank may be
beveled almost to a sharp edge and then laid on the preceding
plank with this edge adjacent to it. When the planks expand
this thin edge will be crushed and the triangular space behind
it partly filled with the crushed wood, thus reducing the danger

198 HANDBOOK FOR CEMENT USERS.

of deformation of the concrete surface. The surface of the
planks may be filled with soap or paraffine to prevent the ap-
pearance of the marks of the grain on the concrete and the
joints may be filled with putty, soap or plaster of paris. Crude
petroleum may be used to fill the pores of the wood. Occasion-
ally strips of cloth are used to prevent the cement mortar
finding its way into the joints between boards. For very fine
work the molds may be covered with plaster of paris. A sand
finish is also possible by using oil or varnish on the molds and
sanding the surface before the oil is dry. The mold may be
lined with sheet iron or steel to give a perfectly smooth sur-
face.

The finer the grain of the surface, the greater care must be
to prevent form marks. With a coarse concrete the joints
between boards may be the only troublesome thing, but if a
jiner concrete or mortar is used on the surface much more care
must be taken to prevent marks.

Joints such as are seen in ashlar masonry can be indicated
by tacking to the forms triangular strips of wood, sheet iron
or sheet steel, which will project into the the concrete arid form
the triangular depressions which represent the bevels cut on
the edges of such ashlar masonry. Any other form of joint can
be made in like manner. These joints can be used to cover the
junctions of metal sheets when molds are lined with sheet iron
.or steel. Ornamental moldings and panels can be constructed
in place by making the molds of proper form and using fine
stone in making the mortar and concrete. Many ornamental
portions of a structure can be made more satisfactorily in sep-
arate molds and set in place as stone would be set. The sec-
tion on artificial stone gives descriptions of methods of con-
struction.

To give a mortar face to a wall, a special mixture may be
deposited next the form as the concrete is deposited, which
must be an inch or more in thickness so that stones from the
concrete will not work through. Frequently this mortar face is
produced by spading back the concrete from the form, thus
forcing the stones back from the face and allowing the mortar
to come to the front. Special tools may be used for this work.
In other cases a plank is set next the form and is removed after

THE USES OF CEMENT. 199

the concrete is in place, its space being filled with the face mor-
tar. A better method is to use a plate partition set the thick-
ness of the mortar face from the mold. The face mortar is
deposited and the plate is withdrawn as the concrete backing
is deposited, thus insuring complete bond of the face and
backing.

. There are several methods of treating the surfaces of con-
crete structures after the molds have been removed in order to
improve the appearance of the face.

The New York Central railroad specifications frequently re-
quire the following procedure when a mortar face is used.
Hard soap is used to fill joints in the forms and the matched
pine surfaces are painted with soft soap. While the concrete
is still green after the removal of the forms the surface is
rubbed with ne grained white fire brick, or with cement brick,
made 1 to 1, into which handles have been cast. The surface
is then dampened and a brush coat of a 1 to 1 grout with fine
sand is applied. This is rubbed in with a wooden float. A cir-
cular motion is given to brick or float and the entire surface is
made as uniform in texture and color as possible. Sidewalk
edgers and jointers are used in making corners, re-entrant an-
gles and joints.

With green concrete a very good effect can be secured in this
way, using water to wash off the surface as the state of the con-
crete will permit.

Railroads use for less conspicuous work a wash made of 1
part cement and 2 parts sand applied with a brush and of a
consistency of whitewash, applied after any cavities in the
face of the concrete have been neatly filled with mortar of the
same proportions as the original, and any marks of joints in
the forms have been rubbed off. The mortar filling should be
well rubbed in. Several specifications for finishing faces of
walls will be found in the next chapter.

The Wabash railway uses for facing concrete abutments a
wash of one part plaster of paris and three parts of cement
made very thin and put on with whitewash brushes. It is
reported to be very satisfactory.

A coat of cement plaster an eighth of an inch thick or more
is sometimes applied as a finish. Occasionally such a coat

200 HANDBOOK FOR CEMENT USERS.

keeps its place and makes a fairly good appearance, especially
if it is applied when the concrete is quite green, the forms hav-
ing been taken off at the earliest possible moment, but the most
frequent experience is the cracking of the plaster and ultimate
scaling off in sections.

When special kinds of stone are used, such as crushed granite,
quarry waste of Bedford stone, or even uniform fine gravel, a
handsome finish can be obtained by dressing the surface of the
concrete as stone would be dressed, with point, pick, chisel or
similar tool. Hammers would not be satisfactory unless the
concrete had become very hard. Any stone can be imitated
by using the same stone crushed in the concrete and coloring
the cement and then dressing the face as may be desired. A
pneumatic hammer with a number of points may be used.
The stones in the surface concrete must not be more than
scinch and the concrete must not be too green. On the other
hand, if it has set too long the work will take greater time and
expense.

Concrete slabs or artificial stone may be used as facing for
monolithic concrete; also natural stone and brick. Natural
stone has been much used for some years, especially in facing
arches and piers, but as men become more expert in finishing
concrete surfaces, concrete or artificial stone is taking its place
and as the troubles with expansion and surface cracks are re-
moved, the necessity for facing is removed so that there is an
increasing tendency toward the use of concrete without facing.

The facing of a bridge in the National Park at Washington,
D. C., was made according to the following specification :

The concrete, which will be on the exterior faces of the
bridge and the parapet walls for a thickness of 18 inches, will
be made of gravel and rounded stone varying in the con-
crete below the belting course between iy 2 and 2 inches in
their smallest diameters. This gravel will be mixed in the con-
crete as aggregate instead of broken stone. The mixture will
consist of one part Portland cement, two parts sand and five
parts of aggregate. The parapet walls will be made in a sim-
ilar manner, with the aggregate composed of gravel not ex-
ceeding 1 inch in its smallest diameter. When the forms are
removed the cement and sand must be brushed from around the
face of the gravel with steel brushes, leaving approximately
half of the gravel exposed.

THE USES OF CEMENT. 201

The line of the roadway, as indicated in*the drawings, will
be marked by a belting course of rock-faced, roughly-squared
stones, or large cobble stones from 6 to 8 inches in size, and a
row of rounded cobbles will be inserted below the top of the
parapet walls, both on the outside and the inside, as shown on
the drawings, composed of stone between 3 and 4 inches in their
smallest diameters.

The soffit of the arch shall have a mortar face of at least
i/^-inch thickness, composed of one part cement and two parts
sand. This facing must be built up at the same time as the
concrete.

Preliminary experiments showed that the concrete was too
green when 12 hours old and too hard when 36 hours old to be
brushed properly, but that good results could be obtained when
the concrete was about 24 hours old.

CRACKING OF CONCRETE.

The cracks which occur in concrete may be assigned to two
general classes, those which are merely surface cracks and
those which extend through the mass.

The fine hair cracks which appear on the surface of some ce-
ment work are attributed to several causes and some of them
have not been very satisfactorily explained. If the surface is
too thoroughly troweled in finishing, or if the concrete forms
a more or less continuous skin on the surface, the difference in
constitution of this thin neat cement skin and the concrete be-
low is sufficient to cause difference in contraction in setting
which produces fine cracks in the surface, which do not enter
the concrete. This cracked skin is soon worn off a sidewalk
or floor, but a vertical wall or the risers of a stairway retain
the cracks often with considerable detriment to their appear-
ance. The rubbing which is described 'in preceding para-
graphs as specified by the New York Central railroad is one
way of removing the objectionable layer from the surface. Ce-
ment washes which are not well rubbed in and cement plasters
are subject to the same troubles.

Cracks in the body of concrete are usually due to the expan-
sion and contraction of the mass, with changes in temperature.
Some of this effect has been attributed to contraction of the
concrete in setting.

Professor W. D. Pence of Purdue University made some ex-

202 HANDBOOK FOR CEMENT USERS.

periments to detertnine the coeefficient of expansion of con-
crete which he reported to the Western Society of Engineers.
The concrete was made according to Thacher's specification,
given in the following chapter. The temperature was changed
by means of a steam jacket surrounding the bar of concrete
and the expansion and temperature were observed by means of
suitable instruments. The results of four tests of bars made
of 1 part Lehigh cement, 2 parts sand and 4 parts broken Bed-
ford stone ran from 0.0000052 to 0.0000057 and averaged
0.0000054 per degree of temperature change. Three results
with Medusa cement and Kankakee stone averaged 0.0000056.
The coefficient of expansion of a bar of solid Kankakee stone
was found to be 0.0000056. One experiment on concrete, 1 part
Lehigh cement, 2 of sand and 4 of gravel gave a coefficient of
0.0000054. Three experiments on concrete, 1 part Medusa
cement and 5 parts gravel gave an average coefficient of
0.0000053. The average of all results for broken stone con-
crete was 0.0000055 and for gravel concrete was 0.0000054.

Professor Hallock of Columbia University gives 0.00000561
as the coefficient for mortar 1:2 and 0.00000655 for broken
stone concrete 1 :3 :5. The latter figure is approximately that
for the linear expansion of steel.

The only method of -preventing injury to the structure in
strength, stability, or most often in appearance only, is to
design it in such manner that the change in volume is properly
taken care of. The method ordinarily applicable is to make
joints entirely through the concrete, that the effects of change
of volume may be concentrated at these joints and thus pre-
serve the integrity of the mass of concrete. Special designs of
of joints must be made if they must be waterproof or if the sec-
tions must be bonded together to act as one. The cracking of
the concrete occurs in a monolithic structure at intervals
averaging about 30 feet and it is customary to make joints at
distances apart of 25 to 50 feet. If a stone or brick facing is
used there must be similar provision of joints in both backing
and facing. Stone masonry and brick masonry to a less extent
are subject to similar cracks but, being usually less homo-
geneous, the cracks occur oftener and along the faces of stones
or bricks rather than directly through the mass.

THE USES OF CEMENT. - 20S

METHODS OF CHANGING TIME OP SETTING OF CEMENT.

Various chemical mixtures are in use for hastening the set-
ting of cement. One of these consists of four different sub-
stances, the action of which seems to be to produce an amor-
phous silica which is in very small proportion to the amount
of material in the mortar in which it is used. The mixture
certainly hardens the concrete rapidly and thoroughly. It has
been suggested by a chemist that the result is obtained by the
action of the small amount of amorphous silica put into the"
mortar in starting a form of crystallization favorable to rapid
hardening. The mixture contains as by-products of the chemi-
cal actions taking place before it is completed ready for addi-
tion to the mortar, some sulphate of iron, which may discolor
the surface, some sulphate of soda, which may produce efflores-
cence and some lead salts, which, so far as they are located on
the surface, may darken in a smoky atmosphere.

Chloride of calcium is frequently used for hardening cement
quickly, small quantities having this effect, while larger quan-
tities may delay the setting.

Chloride of barium is reported by A. Moffatt, chemist, to be
the most satisfactory of this class of substances for hastening
the hardening of concrete.

Sulphate of lime or gypsum retards temporarily the setting
of cement. Professor E. C. Carpenter's experiments show that
1.5 per cent, of gypsum has the maximum retarding effect,
greater or less quantities having less effect. Other cements
would probably give somewhat different results. French ce-
ments, according to Candlot's experiments, take 2 to 4 per
cent, of gypsum to produce the maximum effect. These small
quantities increase the strength of the cement slightly except
in sea water, in which the briquettes with gypsum ultimately
disintegrate. The retarding effect of gypsum seems to be lost
after the cement has stood some days or weeks. Hydrated
lime added to this cement restores the power of the gypsum,
though lime added to cement not containing gypsum has little
retarding effect on the setting.

A weak solution of chloride of calcium in the water used in
making mortar, say 10 grams per liter, retards the setting of
the cement, while larger amounts, such as 100 to 400 grams per

204 HANDBOOK FOR CEMENT USERS.

liter, hasten the setting. It does not seem to injure the cement
or concrete. Experiments in the Cornell University laboratory
indicate that 1 per cent, of chloride of calcium, corresponding
to 30 grams per liter in the French experiments, has the maxi-
mum effect, extending the time of final setting over 3.5 hours.

EFFLORESCENCE.

Efflorescence on concrete surfaces is caused by the carriage
by moisture of soluble substances in the cement or in the aggre-
gates to the surface, where the evaporation of the water leaves
the substance until it is washed or brushed off. If there is too
little water in the concrete when it is deposited, complete com-
bination does not occur in the cement, the concrete is likely to
be somewhat porous and subsequent moisture from any source
has an opportunity to bring the soluble substances mentioned
to the surface. When too much water is used it may separate
the lime from the other ingredients in the cement to some ex-
tent and when it evaporates it leaves the concrete somewhat
porous and brings soluble matters to the surface. Efflores-
cence is its own cure if a sufficient amount of the soluble mat-
ters is brought to the surface to close the pores and make the
mass waterproof, but removal of the deposit prevents this act-
ion and the efflorescence will continue to some extent until the
soluble matters are all brought out. Waterproofing a block will
prevent efflorescence by keeping out the water which brings the
soluble salts to the surface. Mr. Clifford Richardson recom-
mends the addition of a small proportion of slag or some active
form of silica to combine with the free alkali, but lays special
stress on using exactly the proper amount of water in mixing
the concrete.

The efflorescence can be removed by a wash of 1 part hydro-
chloric acid and 5 parts of water well scrubbed on and im-
mediately washed off with a stream of water from hose. In
Washington, D. C., this process applied to a bridge cost about
20 cents a square yard on flat work, but was 60 cents for the
whole work, including balustrades.

In monolithic work efflorescence takes place on vertical
or inclined surfaces most frequently at the plane of junction of
old work with new. A slight skin of denser mortar forms on
the upper surface during tamping, which makes a compara-

THE USES OF CEMENT. 205

tively water-tight layer. Water seeping into concrete from the
rear or from above works it waj- to the outer surface at this
impervious layer and deposits the soluble materials, which it
has brought with it, upon the surface of the concrete as it
evaporates. If this impervious skin, which is very thin, is
removed by brushing and washing with a little more vigor than
is needed to remove loose material before depositing the new
layer of concrete, the water getting into the wall will find its
way farther down and may not get out until it gets below the
surface on which its appearance is objectionable. Sloping
these surfaces of division between layers so that the water will
tend to flow to the back of the wall will aid in some cases.

WATERPROOFING CONCRETE.

Italian experiments show that the porosity of concrete de-
pends on three classes of voids, those in the sand which are not
completely filled with cement, those due to air adhering to the
sand grains and those due to evaporation of excess of water
used in mixing. However, porosity does not follow the same
laws as permeability of the concrete and the conclusions re-
garding permeability of cement by water are as follows : Mor-
tars of fine sand are less permeable than those with coarse
sand ; permeability decreases as proportion of cement increases
and neat cement is the least permeable; concrete made with
700 pounds Portland cement,, 1 cu. yd. mixed sand and 1*4 cu.
yds. of small gravel made into a cylinder with 21/2-inch shell
was impermeable under 13 feet head and barely permeable
under 27 feet, while without the gravel the 'mortar was some
what permeable under 13 feet and very easily so under 27 feet
head. The concrete with the amount of cement increased to
1,150 pounds was impermeable under 40 feet head.

American experiments by Hyde and Smith showed that 1 to
1 mortars were impermeable under 80 pounds pressure per
square inch, (184 feet) when 30 to 45 per cent, of the concrete
aggregate. Some of the concretes with 1 to 2 mortars were
impermeable but others were not. All others leaked under
high pressure. The thickness of concrete was 5 inches and
time of application of pressure 24 hours on all which showed
no leak in 2 hours, with same result. Mixtures of 1 :2 :4 and
1 :2Vi :4 well mixed and placed are practically impermeable.

206 HANDBOOK FOR CEMENT USERS.

but in extreme cases the mixture should probably be somewhat
richer.

If it is desired to make leaner concretes or those not well
compacted waterproof some of the following methods may give
satisfaction :

Mr. Robert W. Lesley, in a discussion before the American
Society of Engineers, states his conclusion that the best addi-
tion to cement mortars for making them impermeable is a
reasonable proportion of slaked lime. If thoroughly hydrated
the lime is safe, it slightly delays the setting of the cement,
and it will effloresce to some extent, but the ultimate formation
of the carbonate of lime closes the pores in the concrete and
makes it impermeable permanently.

One form of preventing the passage of water through a con-
crete or brick wall is that of a thin coat, say %-inch, of a mix-
ture of Portland cement, sand and a chemical termed hydro-
lite. This coating can be applied to the inside of basement,
pits and the like as weir as of swimming pools and tanks and is
said to give satisfaction by adhering to the wall even under
50 pounds of water pressure on the other side of the wall. A
hard finish can be applied on the waterproof coat.

U. S. Government engineers have used Sylvester's process in
fortification work. One specification prepares a wash of 1
pound concentrated lye, and 5 pounds of alum in 2 quarts of
water, to one part of which is added 10 pounds of cement, dark
color preferred. The wash should be applied on a cloudy day
after the wall has been well wet with a hose. The solution
must be kept well stirred after the cement is added.

For cistern work the usual wash is a simple cement grout
applied with a brush in one or two coats, usually to a well-
troweled surface. If the head of water is more than 10 feet,
a coating of asphalt % inch thick in addition will serve up to
60 feet head. Tanks and conduits receive a coat similar to a
cement sidewalk wearing surface, which is well troweled and
applied as wet as it can be to remain in place. Arch rings and
spandrel walls of arches receive similar coats usually without
so much attention to troweling.

When perfect water-tightness is required, however, this class
of work receives a coat of asphalt which is mopped on the mor-

THE USES OF CEMENT. 207

tar coat to a thickness of about % inch and again plastered
with cement mortar before the concrete or filling above is de-
posited. Asphalt mastic is sometimes used with thickness of
y 2 inch, omitting the rich cement mortar. Silicate of soda is
applied with a brush and forms a water proofing by filling the
surface pores. Professor W. K. Hatt added silicate of soda
to the water used in mixing the mortar, diminishing strength
and permeability 50 per cent. It seems to be more satisfac-
tory, therefore, to apply the silicate of soda with' a brush.

Professor W. K. Hatt made a 5 per cent, solution of ground
alum in water and a 7 per cent, solution of soap, used the
alum solution in mixing mortar half as much as the usual per-
centage of water, then added the other half in the form of the
soap solution. The resulting mortar of sand and cement has its
permeability decreased one-half and strength is not affected.
The Sylvester method of applying the alum and soap is appar-
ently more satisfactory, though much more difficult.

Mr. Edward Cunningham added to the cement and sand one
per cent, of powdered alum by weight and to the water one
per cent, of yellow soap, the proportions of cement and sand
being 1 to 2. Mortar without the additions was about 12 times
as permeable as the treated mortar, the passage of water
through the latter being through "pin holes" apparently due
to carelessness in placing. The walls of the test vessels were
% inch thick. A 1,4-inch plaster of similar nature on the inside
of a clear water well rendered it water-tight. The materials
required add about f 1 to the cost of a cubic yard of concrete.

Liebold's (German) patent adds to 100 kilograms Portland
cement clinker 300 grams of Japanese berry wax and 20 grams
of caustic lime dissolved in 8 liters of boiling water thoroughly
mixed and dried. The clinker is then ground in the usual way.
Concrete made with this cement in proper* proportions is said
to be waterproof.

There are numerous secret preparations on the market for
hastening the setting of cement and for making it waterproof,
nearly all of which are probably composed of one or more of
the substances here named or of chemicals which are ultimately
detrimental to the strength or durability of the concrete.

208 HANDBOOK FOR CEMENT USERS.

Care must be takerr in accepting such compositions without full
knowledge of their nature and effects.

There are now on the market solutions of paraffine which are
applied with brush and close the surface pores of concrete,
thus preventing absorption of water and efflorescence.

Anhydrosol, lockpore, Szerelmey stone liquid, dehydratine,
anhydrine, antihydrine, are names of some of the preparations
on the market.

Almost complete impermeability can be attained by proper
selection of sizes of grains of sand and stone, and proper pro-
portions of cement. The principle on which this method is
based is the reduction of the voids in the cement and stone to
a minimum, and the complete filling of these voids with ce-
ment, with as little excess of cement as practicable. An ex-
cess of water seems to aid in producing the proper mixture
and is preferred to a deficiency of water.

A pump room in San Francisco, 50 feet in diameter, with a
thin -reinforced concrete floor and walls of cement 5 feet thick
at bottom and 2 feet at top, is waterproofed by a sheet of as-
phalt roofing felt with asphalt cemented joints laid on the sand
under the floor and a cement coat of asphalt % ^ ncn thick on
the outside of the concrete walls. It is tight under about 18
feet head.

Removal of portions of the old Park avenue tunnel north
of the Grand Central station in New York city uncovered wa-
terproofing of the tunnel masonry laid 33 years ago, which con-
sisted of tarred felt and coal tar. It was in perfect condition.

EFFECT OF OIL ON CONCRETE.

Mr. James C. Hain has made some experiments on the effect
of oil upon concrete which are not conclusive, but show very
serious effects in some instances of animal oils in disintegra-
ting cement mortar. These results were observed in some of
the experiments with lard oil and with signal oil, which is a
mixture of animal and mineral oils. Vegetable oils had less
effect upon concrete and mineral oils, such as petroleum and
its products, had but little effect. In some instances no effect
was produced by any of the oils. Thus far, therefore, it is only
possible to call attention to the fact that sometimes oils of
certain kinds have very serious effects upon concrete. Mr.

THE USES OF CEMENT. 209

Hain made a search for a coating to prevent the action of the
oil but has not vet succeeded in finding it. ^

RETEMPERING CEMENT MORTAR.

It is a common belief among cement workers that cement
mortar is improved by allowing it to take a partial set and
then retempering it. Notwithstanding the fact that there
are a few statements of results of tests which seem to bear
this out, the weight of testimony is to the effect that this
process is detrimental to the strength of the mortar. This is
perhaps shown on the work by the fact that the retempered
mortar sets more slowly than the fresh mortar. The following
results of tests at the Manhattan Railway Company's power
station during its construction, made by Thos. S. Clark, resi-
dent engineer, show the actual effect of retempering upon na-
tural hydraulic cement mortar:

EFFECT OF RETEMPERING ROSENDALE CEMENT MORTARS.

Neat cement with 28 per cent, water. *-~.^_

Libs, per sq. in.

Tensile Strength Retempered

Hours in Water. Age in Days. not Retempered. After 60 Min.

3 1 139 27

24 7 166 64

24 14 180 80

24 28 219 94

24 56 322 180

Mortar 1 cement, 3 sand, 14 per cent water.

24 28 39 31

24 56 73 59

24 112 113 56

The first two lines give averages of 20 to 43 tests; the other
results are averages of 5 to 7 tests.

Portland cement sets more slowly but it will be injured in
like manner by retempering after its first set has begun to
show, probably for most brands within the second hour after
mixing.

EFFECT OF FROST ON CONCRETE.

The effect of cold is to stop the setting of cement. Most
cements set very slowly if at all below a certain tempera-
ture, which is usually between 30 degrees and 40 degrees F.
When the temperature is raised the cement sets, unless in the
meantime the water has evaporated sufficiently to leave an in-
sufficient quantity for the chemical action, so that the freezing

210 HANDBOOK FOR CEMENT USERS.

of work laid in cement mortar usually has the effect simply of
delaying the hardening of the mass. If too much water is used
in the mortar the expansion of the water in freezing may disin-
tegrate the mortar by the mechanical action of the ice in
forming. Either of these effects is most apparent near the
surface of the mass of masonry, and often requires pointing
up of the joints of brick or stone masonry while the remain-
der of the work will be found in good condition. Alternate
freezing and thawing increases the danger of injury. Port-
land cement is seldom injured by freezing, but many natural
cements are more or less injured, and mortar of natural
cement is the more liable to disintegrate even under the best
of conditions, if the temperature is long enough or often
enough below freezing point before it has an opportunity
to set. In a few instances some setting of mortar frozen for
a long time has been observed, but as a rule the setting is
delayed until the temperature again rises above freezing point.
The first method of aiding the setting of mortar which
suggests itself is to delay the time of reaching the freezing
point by heating the stone or brick, the sand/ the cement and
the water. The amount of heat required depends upon the
temperature of the air and the rapidity with which the work
can be done after heating stops. This method is seldom
entirely satisfactory unless very q'uickj-setting cements are
used. Slow-setting cements will evidently give more trouble
than those which set as quickly as can be permitted under
the conditions of time necessary to get the mortar into the
work after the water is added. Mortar should be made
richer than for use at ordinary temepratures, say 1 to l 1 /^
instead of 1 to 2, and other mixtures in the same proportion.
As little water as possible should be used, although this will
increase the probability of requiring pointing of joints or the
crumbling of outer surfaces of concrete. It is frequently
possible to delay freezing by covering the work with straw or
even tarpaulins. If stable manure can be kept in place in
sufficient quantities to keep up its fermentation, it is the
most efficient material for covering, but one complaint of sur-
face disintegration from its use has been reported in Municipal
Engineering. Perhaps the most common method of prevent-

THE USES OF CEMENT. 211

ing the freezing of mortar is the use of a solution of common
salt for mixing. The usual rule is to add 1 per cent, of salt
to the water for every degree of temperature below freezing,
using the minimum temperature to which the masonry will be
subjected for the computation. This amounts to about 1.3
pounds of salt per barrel of cement per degree below freez-
ing. The cold delays the setting of the cement, but there
is no mechanical action from freezing, and the results of this
method are usually quite satisfactory, the pointing of joints
being the only additional operation expected. It is evident
that work to be placed upon concrete laid in freezing weather
must be delayed until the setting of the cement makes the
mass sufficiently stable to carry the weight. Laying of ma-
sonry, especially of massive stone masonry, in freezing
weather is quite easy, but the placing of masses of concrete
in exposed situations or of small sections of concrete is not
so easy nor so certain of success.

In France some experiments have shown that 0.7 pound of
carbonate of soda, dissolved in each gallon of luke warm
water used in making mortars, will gain time in the setting
of cement in cold weather. The amount mentioned corres-
ponds to a temperature of about 14 degrees F., and the
amount of the carbonate of soda may be doubled if necessary,
or reduced. The increase in cost is about 20 cents a cubic yard
of mortar.

Some experiments on the freezing of mortar at the Holyoke
dam showed that freezing reduced the strength about 50 per
cent, except in the case of quick-setting Portland cements,
which were affected but little.

Buildings, and at Chaudiere Falls, Quebec, a dam, have
been built under the protection of canvas or frame sheds in
which the temperature was kept up by means of stoves.

CEMENT IN SEA WATER.

An investigation of the action of sea water upon cement,
made by Mr. Le Chatelier upon rather meager data, leads
him to the conclusions that the principal cause of decomposi-
tion of cements in sea water is the formation of supho-
aluminate of lime, and that the presence of 4 per cent, of
alumina in the cement in form capable of combinations sus-

212 HANDBOOK FOR CEMENT USERS.

ceptible to hydration is dangerous. Cements in which iron is
substituted for alumina are better, the resistance of such
cements to decomposition by sea water being much greater.
Keduction in the amount of lime improves the cement in this
respect, but at the expense of other qualities if too great.
Silicious puzzolan seems to improve cement intended for use
in sea water. Too much importance must not be given to this
report until further experiments or observations are made.

STORAGE OF CEMENT.

Several of the specifications for cement in the preceding
chapter give instructions for the storage of cement. The prin-
cipal requirement of the storage room is dryness. Rain falling
or driven by the wind must be kept from the packages and the
floor must be high enough above the ground to insure that no
ivater can be absorbed from it. Nearly all cements are im-
proved by proper storage and it is a common requirement in
English specifications that cements be spread on a floor in a
perfectly dry warehouse and allowed to "aerate" or "cool" or
""cure" for a fixed number of days. In America this curing is
supposed to take place in the storage bins at the cement fac-
tory, but does not usually seem to be so necessary as with
English cements. The addition of about 2 per cent, of gyp-
sum is often made in grinding, one of the results of which is
that the time of storage may be diminished.

The outer portion of cement in a package may sometimes
harden somewhat from absorption of moisture from the air
without injuring the cement in the interior. The hardened or
lumpy cement should not be used without thorough test, though
sometimes it does not seem to be injured. Cement in sacks is
sometimes hardened by storing in high piles, the lower pack-
ages being compressed by the weight above, and this kind of
lumps should not be mistaken for lumps formed by absorption
of water.

COLORING AND PAINTING CONCRETE.

For coloring cement work mineral colors are generally
used. Nearly all coloring matters reduce the strength of
cement, but ultramarine in small quantities increases it.
Red oxide of iron, if it contains sulphuric acid, may cause

THE USES OF CEMENT. 213

swelling. Black and bluish gray are produced by using dif-
ferent quantities of lamp black or peroxide of manganese;
red, by the best raw iron oxide; bright red, by caput mor-
tuum (expensive) ; a cheaper red by Venetian red; brown, by
the best roasted iron oxide; buff, by ochre; blue, by ultra-
marine; bright blue, by prussian blue.

Cement manufacturers recommend the following quantities
per 100 pounds of cement :

Black, 2 pounds excelsior carbon black.

Blue, 5 to 6 pounds ultramarine.

Brown, 6 pounds roasted iron oxide.

Gray, % pound lamp black.

Green, G pounds ultramarine.

Red, 6 to 10 pounds raw iron oxide.

Bright red, 6 pounds Pompeiian red.

Yellow or buff, 6 to 10 pounds yellow ochre.

It is said that unfading colored cement can be made by mix-
ing with the raw materials before burning chromic oxide for
green, oxide of copper for a blue-green, and equal parts of ox-
ides of iron, manganese and cobalt for a black color. Such
cements are not on the general market, however. Finely
ground oxide of manganese added to the mortar will give a
black color and not weaken the concrete. Venetian red and
lampblack will fade.

White cements are often asked for. There is some difference
in shade of Portland cements and puzzolan cements are usually
the lightest. They are not satisfactory for greatly exposed
work. An English patent makes a white cement by mixing one
part of kaolin, a clay without iron, three to five parts of white
chalk, and two to five per cent, of gypsum, or three to five per
cent, of magnesium chloride. The mixture is burned as any
other cement is burned. The resulting cement would probably
not stand severe exposure to the weather. Lafarge, a French
"grappier" cement is very light colored. The use of white mar-
ble dust in place of sand and puzzolan or lighter cements pro-
duces the best results yet obtained. Sulphate of bariiim, ox-
ide of zinc and sulphate of lead produce a grayish white color,
but their permanence is not guaranteed.

Portland cement concrete must be thoroughly set before

214 HANDBOOK FOR CEMENT USERS.

painting, and a year's age is advisable. The durability of the
paint will be increased by first brushing the concrete surface
with a solution of one part sulphuric acid in 100 parts of water
and allowing it to dry. A coating of one part silicate of soda
in three or four parts of water applied two or three times, with
a washing with water between, is good as preparation for oil
paint.

MOLDS AND FORMS.

With reference to forms or molds Mr. W. A. Rogers says that
their construction for the ordinary low abutment or culvert
wall is a comparatively simple matter. He uses 4x6-inch or
6x6-inch uprights with 2-inch plank surfaced on one side and
two edges, lightly nailed against the posts to form the faces
of the wall. Ten-inch width of plank is convenient for a uniform
size. Front and back faces of form are held together by rods
through opposite posts, and the front is usually braced to
stakes driven in the ground, or to piles. For low culverts and
abutments one rod at bottom and top of each set of posts is
sufficient, the bottom rod being left in and the top rod being
above the upper surface of the finished concrete. If coming
in the concrete, they are cut off at the surface of the concrete
and left in. Sometimes each form can be braced in position
without the cross rods for low w r ork. The face planks must be
placed level and for specially smooth surface the planks are
surfaced on both sides to a specified thickness. The posts are
spaced 5 feet 4 inches or 4 feet centers where 16-foot planks are
used. For high piers posts 6x8 or 8x8 inches are used or two
3-inch planks with 1-inch blocks between them, placed so that
the face planks are nailed against the edges and the rods passed
through the space between planks to nuts and washer against
the outer edge. For arches the lagging is beveled to give a
fairly tight upper surface. A 1-4 round is tacked on each square
turn of the forms to give a rounded corner in the finished wall

If 1-inch sheeting is used the uprights should not be more
than 2 feet apart.

Mr. C. R. Neher offers the following in the paper referred
to on page 135 :

The preparation of forms calls for considerable ingenuity
and every contract requires special study, to the end that
smooth surfaces be left, with unbroken corners, that the swell

THE USES OF CEMENT. 215

ing of the wood does not rupture the concrete or leave dis
torted surfaces ; and that the forms be so designed as to be used
several times, and readily set up and taken down and later on
devoted to other uses. As the charge for forms against the
concrete can seldom be kept below 50 cents per cubic yard for
heavy work, there is always an opportunity for the ingenuity
of the designer, as few rules can be laid down for his guidance.

The use of matched or tongue-and-grooved stuff is not de-
sirable, as concrete fills in the openings and there is no oppor
tunity to expand from moisture. Unmatched boards dry apart
and let the water in the concrete leak out, carrying with it some
of the cement. Later on they swell and buckle and, if used as
interior forms, burst the concrete. The best way devised so
far is to bevel one edge of the boards, using narrow stuff, not
to exceed 6 inches. The sharp edge of the bevel, lying against
the square edge of the adjoining board, allows the edge to crush
when swelling and closes up the joint, preventing buckling.

A coat of soft soap, before filling the forms, prevents the con-
crete from adhering to the forms, which should always be
scraped and brushed with a steel wire brush when taken down

Square corners should be avoided, as they readily chip off,
and where used as interior forms for recesses or cellular con-
struction, a fillet should always be placed in the corners.

Concrete can often be saved by introducing cells in the mass.
These are formed either by cheap hemlock boxes, which can be
left in the work, or by collapsible boxes which can be with-
drawn and used over again. Where weight is desirable, one
man stone can be rammed in the heart of the mass, reducing the
cost very materially.

Where, for economy in handling and other reasons, it is de
sirable to dump the concrete from a considerable height, some
precaution should be taken to avoid having the coarse aggre
gates separate from the rest of the mass. This can be accom-
plished in several ways either by chains loosely stretched at
intervals across a chute or by shelves extending part way across
the chute at an incline, so as to deposit on a corresponding
shelf on the opposite side, so alternating for the length of the
chute. Either of these methods is a direct benefit, as it more
thoroughly mixes the concrete.

The molds on the piers of the approaches to the Mingo bridge
across the Ohio river near Mingo island and the methods of
handling them present some interesting features. The piers
were built in rectangular courses each 8 feet high, except where
other heights were necessary for closure. Each course of each
pier was separately deposited in place, the concrete being mixed

?16 HANDBOOK FOR CEMENT USERS.

wet and filled into the form in less than two hours. Molds were
used several times over, so that not more than 20 per cent, of
the timber required to build up molds for all the piers was
actually used.

A mold was composed of three courses of siding each 2.66
feet high made with 2-inch horizontal boards fastened together
by cleats on the outside. In the largest bottom forms these
boards were 20 feet long and in the smallest forms for top
courses they were 8 feet long. The boards were 6 and 8 inches
wide, tongued and grooved and planed on both sides. The
cleats were 2 by 8 inches in cross section and spaced 4 feet or
less apart. At the ends the cleats were 2 by 4 or 4 by 4 and
served as stops in the corner joints in assembling the mold.
Similar parts of courses were interchangeable and could be cut
off at one end and made ready for the next course above by re-
placing the end cleats. The three courses forming a mold 8
feet high were placed at the same time in a fixed order of sec-
tions, and they were bolted at each corner to two 4-inch by 4-
inch by 8-foot vertical posts, which bound the courses together.
Two vertical reaction beams were placed on each side of the
form. These beams were made of two 2 by 10-inch planks,
small dimension bearing on the vertical cleats, the planks being
kept 1 inch apart by wooden fillers. The reaction beams were
18 feet long, thus fully covering two sections of concrete. On
the ends of the pier these beams were spaced 4 feet apart and
on the sides they were 6 feet apart. The beams on opposite
sides were bolted together by %-inch rods, 8 feet apart vertic-
ally, each beam thus having three such rods. As they crossed
the mold they left a central free space 6 by 4 feet for the passage
of the concrete bucket. The rods were surrounded by light
tin tubes 1 inch in diameter, which were left in the concrete
and filled with grout after the rods had been withdrawn. This
Jbracing was found to be not quite sufficient, as the wet con-
crete used deflected the 2-inch planks of the forms too much
if their span was more than 4 feet. The 6-foot spaces on the
sides of the piers were therefore braced by an intermediate ver-
tical reaction beam, the strain of which was carried by two
horizontal transverse beams to the rods on each side of the
6-foot space spanned by them.

THE USES OF CEMENT. 217

After the concrete in a mold had set, the mold below was
taken off and reset for a new section, the order of removal and
resetting of pieces being: First the long vertical reaction
beams, which were moved up one-half their length and reset on
the bolts at the bottom of the section of concrete just set and
those on the top of the section, the third set of bolts being placed
at the top of the beams, 8 feet above the concrete in place ; sec-
ond, unbolting of lower courses of mold and removal to new
position above, fillers being used and panels being cut as neces-
sary to fit the reduction in size of pier.

J. C. Van Natta has patented a clamp for a wall mold, con-
sisting of two malleable iron rods to project through the form,
and each having attached a cam. A piece of wire is hooked
over each of the projecting ends and the cams are turned untL
the tension on the wire brings the two sides of the form to the
proper bearing and distance apart. The wire tie is embedded
in the concrete, and when the form is ready to remove the cams
are released and the rods of the clamps are pulled out of the
concrete. The small hole left is filled with cement.

The Chicago, Milwaukee & St. Paul railroad uses a similar
device designed by J. C. Ham, which consists of two castings
each having a threaded core and two rounded projections,
which hold in place wires wound round them. One of these
castings is screwed on a rod on each side of the wall and these
rods bear on straining pieces on the outside of the form. The
rods and castings being in place and the wire wound round the
two castings to connect them, the nuts on the rods are tightened
up until they bring the forms into proper position and bearing.
When the concrete has been deposited and has set and the
forms are to be removed, the rods are unscrewed from the
castings and the castings and wire are left in the concrete.
The small holes left on withdrawing the rods may be filled with
cement.

Shute and Henschen have patented a movable form for mold-
ing concrete walls, using slotted gauge plates with finger and
gauge bars for holding the two sides together. A sleeve permits
the removal of these bars after the concrete has set, and the
sleeve can also be removed. The same forms can thus be used

218 HANDBOOK FOR CEMENT USERS.

for successive courses in the same wall and the work can pro-
ceed continuously.

FarrelPs clamps are in use for holding forms together during
construction and reduce the disturbance of the wall in remov-
ing forms to a minimum.

Robert K. Evans, city engineer of Haverhill, Mass., describes
a movable form for concrete sewers used by him as follows :

A plate of steel 14 inch thick and 6 feet 2 inches long, was
bent to a semi-cylinder with an inside radius of 18 inches, and
the sides extended on a tangent to the curve, about 6 inches
above the plane of the horizontal diameter. The front open
end was stiffened by a curved 3-inch angle iron riveted to it,
with a horizontal angle iron riveted across its upper ends, while
the rear open end was held apart by a 2x!/o-inch iron bent down
at the ends, and riveted to the inside of the steel plate near its
top edge. Along the inside of the shell thus formed, longitud-
inal 1%-inch angle irons were riveted with the horizontal leg up,
and 1% inch above the horizontal diameter. These angle irons
served as tracks, or ways, for the support of the inside, or core,
forms. The inside forms were made in 3-foot lengths, and con-
sisted of two ribs made of 2-inch plank, to which narrow strips
of wood were nailed, forming a semi-cylinder, which was cov-
ered with sheet iron.

To facilitate lifting these forms out of the concrete, their
upper edges were spread about *4 inch from a true semi-circle.
Along the inside bottom of each form, a 4x6 inch timber ex-
tended from end to end, passing through the ribs, which were
fastened to it, and a projection on the top of this timber, at the
rear nd of the form, prevented the front end of the following
form from lifting above it.

When all the forms were in place this timber formed a con-
tinuous column for their entire length, against which the jack
reacted in forcing ahead the outer form. Across the top of each
rib a 3x3-inch oak timber was fastened, projecting 6 inches
beyond the sides of the inner form, at such a height that, when
this inner form was dropped into the steel shell, it was held
suspended concentrically within the outer form, leaving an an-
nular space of 6 inches in which to place the concrete. It will
be readily seen that the inner form was then free to slide out at
the rear end of the outer form, while still retaining its concen-
tric position in relation to it.

A partition of 3-inch plank fastened to the back of the curved
angle iron in the forward end of the outer form, to which was
bolted the base of an ordinary track jack, and a second, mova-
ble partition to receive the thrust of the head of the jack, and

THE USES OF CEMENT. 219

made of two layers of 3-inch plank, fitting loosely in the outer
form, and hung from a cross bar sliding on the longitudinal
ways, completed the essential parts of the outfit.

In use the outer form was placed in the trench which has been
excavated to the proper depth, and set to the line and grade.
One of the inner forms was then dropped in, resting on the
ways, and the movable partition brought against the forward
end of this inner form, and held there by slightly tightening
the jack. Concrete was then deposited in the annular space
between the two forms, and rammed by a curved iron rammer.
The jack was then brought into action and, with its base
bolted, as previously stated, to the forward partition fixed in
the outer form, and its head reacting against the movable par-
tition which in turn reacted against the ends of the forward
inner form and of the newly made concrete section, forced the
outer form ahead.

The Collapsible Centering Company has a center for sewer
and conduit work made in sections, the lower sections carrying
a track on which the upper sections can be carried forward
when ready for removal and setting ahead.

Thomas A. Burrows has invented a collapsible steel form for
any cross section of sewer, the sections of the form being forced
to place and released by sleeve nuts.

DEPOSITING CONCRETE UNDER WATER.

During the construction of the Holyoke dam in Massachu-
setts an experiment was made to illustrate the effect of dump-
ing concrete into place under water. A batch of concrete was
mixed, 1 part cement, 2*4 parts sand and 5 parts broken stone,
as required on the work, and dropped before setting into a pail
of water. At the end of 12 months it was examined. About %
inch of nearly neat cement, hard set, was found as a top layer,
then about 2y 2 inches of sand, with enough cement to hold to-
gether and a few stones, then 2 to 3 inches of sand and stone
nearly separate and perfectly clean, with no adhesion what-
ever. This indicates that separation of materials dropped into
place through water is too serious to be neglected.

On a large bridge at Ottawa, Canada, a concrete "kibble"
was used for dumping concrete in the foundation under water,
which was found very satisfactory. It is a steel bucket, wedge
shaped and hung by six chains to the four corners and the
hinges at the middles of the short sides, which meet in a ring

220 HANDBOOK FOR CEMENT USERS.

above the center of the bucket by which it is hung from the
operating cable. The box is filled with concrete and the top
covered with a canvas securely tied, lowered to the place of de-
posit and the latch of the bottom tripped, when the long sides
swing on the hinges mentioned, enough to let the concrete slide
out. The wedge shape causes little disturbance to the water in
passing through and the batch of concrete is deposited with a
minimum of unprotected movement through the water. Tests
for wash were made by dropping the filled kibble 60 feet
through the water at the usual speed and again elevating it to
the surface and depositing the concrete in barrels on the sur-
face, and also by depositing it in a box 8 feet under the sur-
face, where it was obliged to drop the 3 feet of depth of the box
through the water, a very severe test. The first test was satis-
factory, an excellent core being -obtained with a diamond drill %
The second test gave no core, but the walls of the drill hole stood
hard and firm.

In building the pier at Superior Entry, Wis., the concrete
was deposited in molds under water, by using buckets with
drop bottoms. Each bucket had two canvas covers 3 by 4 feet
in size, weighted with 110 pieces of lead each 3 by 1 by 1-16
inch. One was fastened on each side of the top of the bucket,
and \vhen the bucket was filled with concrete they were folded
over it, thus effectually preventing wash of the concrete as the
bucket descended through the water, discoloration of the water
being seldom seen during the lowering of the bucket. The con-
crete was mixed quite wet, and when the bottom latch was
tripped it slid out of the bucket and into its place easily and
quickly.

At the Nussdorf lock, Vienna, Austria, three trolleys were
run over the lock, the three covering the entire area. Each
trolley carried a vertical tube which was telescopic, and thus
could be shortened as the work progressed. Three chutes on
each car made delivery of concrete to the tube convenient, from
dump cars running on service tracks.

MIXING CONCRETE BY HAND.

The specifications in the next chapter give instructions re-
garding mixing of concrete. The important points are careful
measurement and thorough mixture, dry and wet. Specifica-

THE USES OF CEMENT. 221

tions are often not definite in regard to the method of deter-
mining the exact amounts of material required. Usually the
cement and sand are mixed dry and the stone or gravel and
water is then added, practice varying as to order of doing this.
The gravel or stone is occasionally added dry and water then
added in a central basin formed in the mass or by hose,
sprinkler or bucket, as the mass is turned over. More fre-
quently the water is added to the mortar and it is then thrown
over the stone and turned over with it or the stone is dumped
into the mortar and the mass then turned over until it is thor-
oughly mixed according to the specifications in use, there being
considerable difference in requirements as to methods of mix-
ing and number of times turning over, dry and wet, as the speci-
fications referred to will show.

Perhaps the most common method, where accuracy in propor-
tions is required, is to deposit the stone or gravel in a measur-
ing box, preferably bottomless, so that it can be removed read-
ily, to a fixed and uniform depth, then put in a layer of sand
of proportionate thickness and complete with a layer of
cement. This mass is then turned over dry with shovels by
four men working at the ends and turning out. It is then
turned back again toward the center, and this is repeated as
often as the specifications require. The water is then added,
partly in a crater cut in the top of the rounded pile of concrete
and partly by sprinkler, while the men are again turning the
mass over from and towards the center until it is thoroughly
mixed.

CONCRETE MIXERS.

Concrete is more quickly mixed by machine and more thor-
oughly. A smaller amount of cement, say ten per cent,
can, therefore, be used to secure the same strength of
concrete. The uniformity of the concrete makes expansion
and contraction of all parts of the mass the same under the
same conditions, thus preventing disintegration on this ac-
count.

The simplest concrete mixer is the portable gravity mixer,
which is a simple chute of rectangular cross section, pro-
vided with deflecting plates arranged alternately on two
opposite sides of the tube and also perhaps with pins project-

222 HANDBOOK FOR CEMENT USERS.

ing into the path of the materials. The materials are depos
ited in layers on measuring platforms or boxes and shoveled
into the chute, or may be discharged into it by tipping the
measuring boxes. Water may be added with the other ma-
terials or, as in one machine, may be sprayed upon the other
materials as they pass through the chute, the rate of delivery
of the water being under the control of the man at the deliv-
ery end. The mixed concrete is received in carts or barrows
and is ready for deposit in its place upon the work. With
proper care in shoveling or discharging the materials into the
chute, and a careful man in control of the water, very excel-
lent results are obtained. Another gravity mixer consists of
four hoppers each of which receives the concrete ingredients in
layers, cement at bottom, then sand, then stone. They are
dumped through chutes into a single large hopper below and
thence as desired to a second large hopper and from this to
carts.

Another simple form of mixer which is also continuous in
its action is a screw-conveyor in a box of proper form, the
materials being dumped in at one end by shovel or tip, as in
the case of the gravity mixer, and discharged at will from
the other end. In some cases two or more of these mixing
troughs are so set that the first will discharge into the sec-
ond, and so on, and the mixtures of cement and sand, of water
and of stone or other aggregate can be made separately or in
any form desired. The water is usually applied by hose in the
mixer of cement and sand, if more than one is used, and if the
delivery of materials is continuous and uniform can be auto-
matic. Practically, the hose nozzle must usually be in the
hands of a man or boy with some experience. There is a
slight opportunity to correct errors in discharge of materials
into the machine by delaying delivery at the outlet. Power,
from electric motor, gas or steam engine or other motor is ne-
cessary to run the machine. Arms on an axis, so formed as to
move the material toward one end of the machine, take the
place of the screw conveyor in one design.

There are many styles of batch mixers, into which a given
quantity of the materials is discharged, the mixing per-
formed and the concrete discharged. These are under per-

THE USES OF CEMENT. 223

feet control, and any desired amount of mixing can be given
each batch. Several of the designs are cylinders or double in-
verted truncated cones, with deflecting blades, so arranged
that materials deposited in one end by hopper and tube at the
axis of the machine, are gradually moved toward the other
end of the machine while being turned over by the revolution
of the cylinder on its axis. In one machine the batch is
dumped from the discharge end without stopping the ma-
chine, so that it is practically continuous in its action, the
barrow full of materials dumped in at one end being dropped
out mixed at the other, and one batch following another as
rapidly as the barrows can be wheeled up and tipped at one
end and filled and wheeled away at the other. An addition
of bins with automatic measuring devices for depositing ma-
terials in the cylinder makes an automatic and continuously
acting batch mixer, which, at some expenditure of power, will
mix the concrete with less manual labor if properly super-
vised by expert machinists. In another design the cylinder
or double cone is tipped, at will, to dump the mixture into
the cart.

Still another batch mixer is a trough with a series of arms
set on a revolving axis, which turns over the materials de-
posited in the box until they are thoroughly mixed, when the
bottom of the box is opened and the mixture dumped through
a hopper into cart or barrow beneath. Some of this class have
two such sets of revolving arms meshing together on their up-
ward turn.

Most of the batch mixers require power from gas, gaso-
line or steam engine or electric motor, though some of the smal-
ler and simpler machines can be run by hand. A gearing for
use with horse power, one, two or four horses, as desired, is
furnished by some manufacturers of machines. A batch mixer
for use on street work, or in places where a horse can be driven,
is composed of a cylinder set on an axle supported on two
wheels. A cover opens to let the materials in, the cylinder
turns while the horse is drawing the cart from the material
supply to the place of deposit, where it opens and drops the
mixture.

A cube hung on trunnions at two opposite corners is a thor-

224 HANDBOOK FOR CEMENT USERS.

ough mixer of materials without the necessity of guides or arms
so that the chance for sticking of concrete to the machine is
reduced to a minimum, the inside of the box being smooth and
the passage of materials unimpeded. This is a batch mixer
and water may be introduced in exactly measured quantities
through the hollow axis.

The revolving pan mixer consists of an open circular revolv-
ing pan with plows on a fixed axis which stir up the materials
as they are brought round by the pan. The mixture is dumped
through trap doors in the bottom.

One form of automatic concrete mixer measures the propor-
tions of materials, the cement, sand and stone being deposited
in hoppers from which they are fed in fixed proportions by
means of spiral conveyors to buckets on an endless chain ele-
vator which discharge into one end of a drum, where the dry
mixing is performed by means of steel paddles, which thrust
the mixture to the other end, where a spray of water is applied,
proportioned to the speed of operation of the machine. The
^wet mixture is then discharged into barrows or conveyors.
This machine is continuous in its action.

Another automatic machine is all contained in a single cylin-
der and a hopper with as many divisions in use as there are
materials to mix for the concrete. Buckets on the outside of
the cylinder pick up the materials from a trough at the bottom
of the hopper, are struck off level as they rise and discharge
at the top of the revolving cylinder upon deflectors inside the
cylinder, which mixes the materials dry as they are moved on by
the deflectors. Water is added through the axis of the ma-
chine and the final wet mixture is discharged into barrows by
means of a chute which receives it near the top of the cylinder
from the last deflector. The chute can be tipped to stop the dis-
charge of the concrete temporarily.

One machine has a traveling belt on which the wet mixture
is deposited. The belt runs to the end of a boom which can be
revolved through an angle of several degrees. The concrete
drops off the end of the boom and, when the machine is used
for street work, can be leveled off and tamped with a minimum
of handling. The machine can also be fitted with apparatus

THE USES OF CEMENT. 225

for hauling it forward slowly as the sheet of concrete is com-
pleted.

Since the establishment of the cement block industry there
has been a demand for small mixers run by horse or hand
power, or small gas, gasoline or electric motor. Several of
these machines using the same principles as those described
above are now on the market.

In a recent report of the Chief of Engineers, U. S. Army, is a
description by Clarence Coleman of a device for supplying a
fixed quantity of water to a concrete mixer. It is a barrel
fitted with a 2%-i n ch inlet pipe, on the side near the bottom,
a 2-inch outlet pipe in the bottom movable by means of a lever
to vary the point of taking the discharge from the barrel, and a
%-inch vent pipe in the top, extending up to the level of the
surface of the water in the reservoir- from which the water is
drawn. The outlet pipe slides in a larger pipe set in the bot-
tom of the barrel and has a valve to stop the discharge of water
at will. The valves on the outlet and inlet pipes are operated
by the same rod, so that one is closed while the other is open.
The amount of water to be discharged for each batch of con-
crete being known, the top of the 2-inch pipe is set so that this
amount will be discharged through it from the full barrel when
the outlet valve is opened, any water below the level of the top
of the pipe remaining in the barrel. A weight keeps the inlet
valve open and the outlet valve closed and water runs in until
it reaches in the vent pipe the level of water in the reservoir.
When the water is to be added to a batch of concrete, the opera-
tor pulls the valve rod, opening the outlet and closing the inlet.
When the water has run out, he lets go the rod and the weight
sets the valves for filling the barrel again.

SPECIFICATIONS FOR THE USE OF CEMENT

A number of sample specifications for the use of cement
will be given in this chapter. The list could be very largely
increased without entirely covering all the corners of the
field, but it is believed that enough forms for all the principal
kinds of work have been given to make it possible to deter-
mine the average specifications for good work which will con-
form to the standards of good work which are here presented.

Special uses, such as statuary, tiling, etc., and its use in
large work requiring special study and special machinery are
not considered, as the space at command is more than full of.
the requirements for uses which are general in their charac-
ter. It is not possible to follow any single program in ar-
ranging these specifications, but they will be found to be
grouped as nearly as possible according to similarity of use
or of composition of material, and the index will serve to
locate any particular specification which is desired.

EXTRACTS FROM SPECIFICATIONS OF ILLINOIS CENTRAL RAILWAY
FOR CONCRETE WORK.

Concrete materials are specified as follows:

Crushed Limestone. This shall be made by crushing
tough, hard, clean limestone and screening same through
2-inch meshes or holes. The engineer or inspector in charge
shall reject crushed limestone which may have any of the
following defects: A, containing more than 1 per cent, of
earthy or clayey matter; B, more than 20 per cent, of fine
stone or stone dust, less than % inch in size; C, more than 5
per cent, of soft or rotten limestone which can be crushed
or powdered up in the fingers; D, more than 10 per cent, of
flat stones larger than 2 inches in greatest dimensions; E,
more than 15 per cent, of crushed stone larger than specified
(passing through a 2-inch mesh), unless there be an equal
amount of fine material less than y 2 inch size ; F, if any of the
five classes of defective stone above named can be modified
by mixing with additional material or by breaking large stone
by hand, its use may be permitted under the direction of the
engineer or inspector in charge; G, the use of clean gravel in
place of not more than half of the specified amount of crushed

SPECIFICATIONS FOR THE USE OF CEMENT. 227

limestone may be permitted at the option of the chief engi-
neer, or his authorized representative; but the work shall be
done under such special instructions as shall be given in each
individual case, depending on the quality of the gravel used
and other existing conditions.

Crushed Granite. This shall generally be used of two
sizes; a fine crushed granite, to be used as a substitute for
sand, and a coarser size, particles of which are not larger
than % inch in greatest dimensions, and to be used as a sub-
stitute for crushed limestone in making bridge seats, pedestal
stones, etc. All crushed granite shall be clean, entirely free
from dust and earthy or clayey matter, and each grade shall
be of practically uniform size. This material shall always be
handled on platforms or plank, or in some way kept entirely
free from admixture of earth, sand, etc.

Sand. This shall consist of clean, sharp sand ("pit" or
"bank" sand being preferred), and sand shall not be rejected
if containing occasionally pieces of small gravel. A sand is
preferred which will not pass through a sieve having 30
meshes to the inch. Sand shall be free from earth or alluvial
matter; and, when tested by stirring with water or by rub-
bing in the hands, shall not show the existence of more than
0.5 per cent, of loam, clay or earth. No sand shall be used
for the outside finish of any concrete which contains small
particles of coal or lignite, although sand of this character
may be accepted for foundation concrete, or for the interior
portion of any heavy piece of concrete work.

Cement. This shall in all cases be approved by the engi-
neer of bridges, and the inspector in charge of the work 'shall
receive a written approval before permitting concrete to be
made from any cement delivered. Where possible?, cement
shall be delivered in time to have samples properly taken and
sent to the office of the engineer of bridges, for making the
usual one-day and seven-day tests of neat cement. Contrac-
tors shall provide store-houses at the site of the several pieces
of work in which to unload and store cement. Cement which
is delivered on board cars must be unloaded promptly and
stored in such warehouse, and the cars returned to the com-
pany's service. In no case will it be permitted to retain box
cars on the work for the storage of cement. Cars which may
be so held shall be charged to the contractors at the rate of
one dollar ($1.00) per day for each day after the second day so
held not unloaded. Contractors shall be responsible for the
proper care of this cement after it has been received and
stored, and any cement injured through carelessness or neg-
lect shall be rejected promptly by the inspector in charge. No

228 HANDBOOK FOR CEMENT USERS.

brand of cement shall be used in any concrete work which has
not been accepted in writing by the engineer of bridges, such
acceptance to be based upon regular tests, where possible.
The inspector shall from time to time, make small pats of
pure cement, and of cement mixed with sand, to satisfy him-
self that the cement actually used is of uniform character,
and has not been injured by exposure to weather or in any
other way, and may reject any cement which is wet or
lumpy, or which fails to set properly in sample pats, and the
contractor shall remove the same promptly from the work.

Natural Cement Concrete. This may be used where foun-
dations are entirely submerged below low-water mark or
where there is no risk of the same being exposed to the action
of the weather by cutting away the surrounding earth. It,
however, shall be used only where a firm and uniform foun-
dation is found to exist after excavations are completed. In
all cases where foundations are liable to be exposed to the
action of the water, or where the material in the bottom of
excavations is soft or of unequal firmness, Portland cement
concrete must be employed for foundation work.

The natural cement concrete shall usually be made in the
proportions (by measure) of 1 part of approved cement to 2
parts of sand and 5 parts of crushed stone, all of character as
above specified. For Portland cement concrete foundations 1
part of approved cement, 3 parts of sand and 6 parts of
crushed stone may be used. Wherever in the judgment of the
engineer or inspector in charge of the work, a stronger con-
crete is required than is above specified, the proportions of
sand and crushed stone employed may be reduced, a natural
cement concrete of 1, 2 and 4, and a Portland cement concrete
of 1, 2 and 5 being substituted for those above specified.

Portland Cement Concrete. Concrete for the bodies of
piers and abutments, for all wing-walls for same, and for the
bench walls of arch culverts shall generally be made in the
proportions (by measure) of 1 part of cement, 2% parts of
sand and 6 parts of crushed stone. Where special strength
may be required for any of this work, concrete in the propor-
tions of 1, 2 and 5 may be used; but all such cases shall be
submitted to the judgment of the engineer of bridges, before
any change from the usual specifications is to be allowed.

For arch rings of arch culverts and for parapet headwalls
and copings to same, Portland cement concrete, in propor-
tions of 1, 2 and 5 shall generally be used. Concrete of these
proportions shall also generally be used for parapet walls
behind bridge seats of piers or abutments, and for the fin-
ished copings (if used) on wing-walls of concrete abutments,

SPECIFICATIONS FOR THE USE OF CEMENT. 229

also for arch work in combination with I-beams or in combi-
nation with iron work for transverse loading.

Bridge seats of piers and abutments and copings of con-
crete masonry which are to carry pedestals for girders or
longer spans of iron work, shall generally be made of crushed
granite and Portland cement, in the proportion (by measure)
of 1 part of approved cement, 2 parts of fine granite screen-
ings and 3 parts of coarser granite screenings, the larger
of which shall not exceed % inch in greatest dimension.

Mixing Concrete. All concrete must be mixed on substan-
tial platforms of plank or boards securely fastened together,
so that the various materials of the concrete can be kept en-
tirely free from admixture of foreign matter. Hand-mixed
concrete shall not be made in batches of more than one yard
in each batch. The proper amount of the several kinds of
material shall be measured in some way which is entirely
satisfactory to the engineer or inspector in charge of the
work, so that they may be satisfied that the requisite pro-
portions of each kind of material are delivered for each batch
of concrete. Satisfactory methods of measurement will be
the use of headless and bottomless barrels for measuring
sand and broken stone; the use of boxes into which the sand
and stone may be cast and leveled off (the boxes then being
removed), or the use of square and uniform sized wheelbar-
rows, expressly designed for this purpose. The measurement
of sand and broken stone in the ordinary shallow, round bot-
tom wheelbarrows will not be considered satisfactory, and
shall not be permitted.

The detail of mixing concrete by hand shall be generally as
follows: The proper amount of sand shall be measured out
and spread upon the concrete platform, and the proper
amount of cement shall be delivered and spread upon the
same; the sand and cement shall be turned over dry, either
by means of shovels or hoes, until they are evenly mixed.
They shall then be wet and made into a rather thin mortar,
and shall then again be spread into a uniform and thin layer
upon the concrete platform. The proper amount of concrete
stone (the same having been previously drenched with water)
shall be spread upon the mortar, and the whole shall be
turned over at least twice, either by shovels or hoes, before
it is loaded into wheelbarrows, or in any other way taken to
be placed in the work. In wetting the mixture of sand and
cement to make the mortar, and in wetting the subsequent
mixture of stone, sand and cement (if necessary), a spray
or sprinkler shall be used. The water must not be dashed
upon the mass in buckets or large quantities, or by means of

233 HANDBOOK FOR CEMENT USERS.

a jet. The inspector shall insist that the resultant mixture
of sand, cement and stone be as nearly as possible uniform in
character, the mortar being equally distributed throughout
the mass of the stone. The inspector shall also see that the
mixture is neither too wet nor too dry. It should be of such
a consistency that, when thoroughly rammed, it will quake
slightly, but it should not be thin enough to quake in the
barrow, or before ramming. The inspector shall satisfy
himself that the proper proportions of cement, sand and
stone are used, checking from day to day or from time to time
with the total amount of each which is received and used.

Machine-mixed concrete shall be made of the same general
consistency as the hand-mixed concrete above specified.
Proper precautions shall be taken to see that the requisite
proportions of the different ingredients are used. If machines
are used which are not provided with devices to deliver each
of them, the process of making the concrete shall generally
be as follows : The proper amount of sand, cement and stone
for a batch not to exceed one yard of concrete shall be deliv-
ered on the platform and roughly mixed together so that
when the dry mass is cut down and delivered to the mixer
by means of shovels proper amounts of each of the ingredi-
ents are handled in each shovelful.

It will not be regarded as a satisfactory process to deliver
crushed stone, sand and cement at random to the mixer with-
out taking some special means, as above described, to insure
the delivery of the proper quantities of each ingredient as
nearly as may be simultaneously.

Molds. Molds of substantial character shall be made in
which to construct all concrete work. The material for these
molds shall be furnished by the contractor, and the expense
of furnishing this material and of constructing and removing
all molds shall be covered in the price per yard paid to the
contractor for the several classes of concrete work called for.
The face of the mold next to the concrete shall be finished
smooth, planks which are dressed at least on one side being
employed for this purpose. Material for the molds shall be
of sufficient strength so that they shall be practically unyield-
ing during the process of filling, tamping, etc. The different
gether, if desired, by tie rods or wires extending through the
parts of the frame work for the mold may be fastened to-
concrete. If tie rods are used they shall be so designed that
no iron work will be left outside of the concrete or within less
than 2 inches from the face of the same when the molds are
removed. This may be accomplished by sleeve nut connec-
tions which will permit the removal of the projecting ends of

SPECIFICATIONS FOR THE USE OF CEMENT. 231

bolts or rods, etc., leaving only small holes in the concrete
which can be stopped with pointing mortar after removing
the molds. Another satisfactory method of bracing molds is
to construct them with cross ties between the front and back,
these ties to be placed at frequent intervals above the lower
portion of the mold and to be removed as the concrete is
built up, the studding out of which the molds are constructed
being sufficiently long to extend above the top of the finished
masonry, and at least one set of ties being used above this
level. In general 2-inch plank, sized to approximately 1%
inches thickness, shall be used for the facing of all molds,
and studding for frames shall be placed at intervals of not
more than 4 feet. The planking forming the lining of the
molds shall invariably be fastened to the studding in per-
fectly horizontal lines, the ends of these planks shall be
neatly butted against each other, and the inner surface of the
mold shall be as nearly as possible perfectly smooth, without
crevices or offsets between the sides or ends of adjacent
planks. Where planks are used a second time they shall be
thoroughly cleaned, and, if necessary, the sides and ends
shall be freshly jointed so as to make a perfectly smooth fin-
ish to the concrete.

The molds for projecting copings, bridge seats, parapet
walls and all finished work shall be constructed in a first-
class, workmanlike manner, and shall be thoroughly braced
and tied together, dressed surfaces only being exposed to the
contact of concrete, and these surfaces shall be soaped or
oiled if necessary, so as to make a smoothly finished piece of
work. The top surfaces of all bridge seats, parapets, etc.,
shall be made perfectly level, unless otherwise provided in the
plans, and shall be finished with long, straight edges, and all
beveled surfaces or washes shall be constructed in a true and
uniform manner. Special care shall be taken in the construc-
tion of the vertical angles of the masonry, and where I-beams
or other iron work are not used in the same, small wooden
strips shall be set in the corners of the mold, so as to cut off
the corners at an angle of 45 degrees, leaving a beveled face
about li/2 to 2 inches wide, instead of a right-angled corner.

Where wing walls are called for which have slopes corres-
ponding to the angle of repose of earth embankments, these
slopes shall be finished in straight lines and surfaces, the
mold for such wing walls and slopes being constructed with
its top at the proper slope, so that the concrete work on the
slope may be finished in short sections, say from 3 to 4 feet
in length, and bonded into the concrete of the horizontal sec-
tions before the same shall be set, each short section of

232 HANDBOOK FOR CEMENT USERS.

sloped surface being grooved with a cross line separating it
from adjacent sections. It will not be permitted to finish the
top surface of such sloped wing walls by plastering fresh con-
crete upon the top of concrete which has already set, but the
finished work must be made each day as the horizontal layers
are carried up, to accomplish which the mold must be con-
structed complete at the outset; or, if the wing wall is very
high, short sections of the mold, including the form for the
slopes, must be completed as the horizontal planking is put
in place.

Foundation concrete may be put into excavations without
the use of molds, provided the sides of the excavations are rea-
sonably true and the material is sufficiently firm, so that the
concrete may be rammed thoroughly without yielding to the
adjacent earth. Where a cheaper kind of concrete is used for
foundation work, the top of the same shall be finished smooth
and level, the corners and edges being thoroughly rammed
and compacted, and the whole surface filled full of mortar.
It will not be satisfactory to leave a honey-combed surface or
one on which a lot of loose concrete is left scattered about.

It is not expected that the surface of such foundation work
shall be accurately leveled unless cut-stone masonry is to be
built upon it, but the inspector must insist that that portion
of such foundation concrete which projects outside of the
masonry which is to be built upon the foundation must be
thoroughly rammed and compacted, and must have a finished
surface. If this can not be accomplished without constructing
a mold for the upper portion of such foundation, the con-
tractor shall furnish material and construct such mold, and
the cost of the same shall be included in the price of the foun-
dation concrete.

Iron rails to be furnished by the railroad company shall be
laid and embedded in such manner as may be specified in such
foundation concrete as in the opinion of the engineer of
bridges needs such strengthening, and no extra charge, except
the actual cost of handling the same, shall be made by the
contractor for such work, but the volume of such iron shall be
estimated as concrete.

Where I-beams are to be placed in the angles of concrete
piers as a protection against ice, drift, etc., these shall be set
up and securely held in position so that they will extend 1
foot or more into the foundation concrete. The planking of
molds shall be fitted carefully to the projecting angle of
these I-beams and small fillets of wood shall be fitted in be-
tween the inner faces of the mold and the rounded edges of
the I-beam flanges so that no sharp projecting angle of con-
crete will be formed as the work is constructed.

SPECIFICATIONS FOR THE USE OF CEMENT.

These fillets may be made in short pieces and fastened
neatly into the mold as the layers of concrete are carried up.
Such I-beams will generally be furnished of sufficient length
to extend at least 6 inches above the top of the battered ma-
sonry into the concrete coping, and special pains shall be
taken to tamp the concrete thoroughly around the I-beams,
and to finish the coping above and around the ends of the
iron work.

Where anchor bolts for bridge-seat castings are required
they shall be set in place and held firmly as to position and
elevation, by templets, securely fastened to the mold and
framing. Such I-beams and anchor bolts shall be embedded
in the, concrete work without additional expense beyond the
price to be paid per yard for the several classes of concrete
in which such iron is placed, the volume of iron being esti-
mated as concrete.

After the work is finished and thoroughly set all molds
shall be removed by the contractor. They shall generally be
allowed to stand not less than 48 hours after the last con-
crete work shall have been done. In cold weather molds
shall be allowed to stand a longer period before being re-
moved, depending upon the degree of cold. No molds shall be
removed in freezing weather, nor until after the concrete
shall have had at least 48 hours, with the thermometer at or
above 40 degrees F., in which to set.

Placing Concrete. Concrete shall generally be placed in
the work in layers not exceeding 6 inches in thickness, and, in
general, one layer shall be entirely completed before another
one is commenced. If delivered by wheelbarrows it shall be
dumped as closely as possible where required, so as to avoid
as much as possible the handling or turning over of the same by
means of shovels within the excavation or mold. Where it is
not practicable entirely to complete one layer before com-
mencing a second one, a plank 6 inches wide or more shall
be securely fastened into the excavation or mold, against
which the end of the layer of concrete shall be rammed, thus
providing for a vertical joint in this layer of concrete, and if
a second layer has to be stopped short of the full length of
the work, a second cross plank, placed at least 1 foot back
from the end of the first layer, shall be secured to the excava-
tion or to the mold, against which to ram the second layer of
concrete. Layers of concrete masonry must not be tapered
oft' in wedge-shaped slopes, but must be built with square
ends in the method above described, and the surface of each
projection shall be finished hard and smooth, and flushed full
of mortar, no porosities or loose stone being left thereon.

234 HANDBOOK FOR CEMENT USERS.

Layers must not be made of greater thickness than 6 inches,
unless specially permitted, and each layer must be thor-
oughly rammed,, and the concrete must be of such consistency
that heavy ramming will produce a slight quaking action. In
other words, the concrete must be so thoroughly compacted
that there will be no pores or open spaces between the stone
of which it consists, which are not thoroughly filled with
mortar.

The inspector shall insist upon the thorough compacting
and ramming of all concrete, and shall see that a sufficient
number of men, furnished with suitable rammers, are as-
signed to this work. Enough men shall be employed ram-
ming so that each batch may be spread and rammed before
another batch is dumped within the mold. The ramming
must be completed as the work progresses.

Foundation concrete, if put into excavations which are not
protected by molds, need not have any special attention given
to the finish of the concrete against the earth around it.
Where it is necessary to use molds in the construction of
foundation work the finer material of the concrete shall be
worked to the outer portion of the mass against the molds,
so as to insure the filling with mortar of all pores or open
spaces between the concrete stone. As before described, the
top surface of all foundation concrete shall be finished so
that no loose stone or open and porous places are left upon
the same, especially in the portions of the foundation which
project outside the upper portion of the work. If necessary,
the inspector shall have the contractor make batches of mor-
tar, consisting of 1 part of cement to 3 parts of sand, the
same being thoroughly mixed, and shall cover the whole sur-
face of the foundation concrete with enough of this mortar
to flush full all such open, porous places.

A facing of mortar, consisting of 1 part of cement (by.
measure) to 2 parts of sand, shall be put in next to the molds,
for all Portland cement concrete work for piers, abutments,
arches, wing walls, parapet walls, and any other places where
directed by the engineer in charge, to form a finish for all
such parts of the above classes of work as are to be exposed
to the weather, or which are liable to become exposed. A
similar facing shall be used for the top surface of all con-
crete masonry not finished in the style of sidewalk work.

It is not intended to use such a facing on the backs of abut-
ments or wing walls, against which earth filling is to be
placed, and where the same must necessarily be maintained,
but the same shall be used for the faces and for the upper 12
inches on the backs of all wing walls, for the backs of parapet

SPECIFIPATIONS FOR THE USE OF CEMENT. 235

walls, for the intrados of all arch work,, and as a plastering
on the outside of the same, and in all such places where the
washing away of earth may expose concerte work to the
action of the weather. It is not intended to use such facing
for any copings, bridge-seats, parapets, etc., which are to be
of granitoid construction. The exact thickness of l 1 /^ inches
for this facing shall be secured in the following manner: A
piece of sheet iron 6 inches in width (the height of one course
of concrete) and of any convenient length, say from 6 feet
upwards, having small angle irons, the projecting leg of
which shall be iy 2 inches in width, riveted to its face at inter-
vals of about 2 feet and provided with handles standing above
the upper edge at or near each end, shall be furnished by the
contractor for use at each piece of work where necessary.
This piece of iron plate, if placed with the projecting angles
against the face of the mold, will leave a space of IVo inches
between it and the mold. This space shall be filled with the
mortar required for the facing, which mortar shall be mixed
in small batches from time to time as needed for the work.
When the space between the iron plate and the mold is filled
and tamped with a shovel or other tool to insure complete
filling of the whole space between the iron plate and the face
of the mold, and when the layer of ordinary concrete is backed
up against this iron plate, it is to be withdrawn by means of
the handles and the whole mass of concrete rammed in one
uniform layer. The inspector shall see that the space of l 1 /^
inches is entirely filled with the mortar, which should be of
such consistency that it will flow somewhat freely. At the
same time this mortar must not be made so thin that the
crushed stone may be forced through it in the process of
ramming. By using the mold in the manner above described
the face of each layer may be made of exactly the right
amount of mortar, and the proper thickness of the layer may
be accurately determined. The intention is that the facing
and the backing shall be rammed and set together. In no
case is one to be put in in advance of the other, or so that
either may be set before the other. In no case shall the inspec-
tor or engineer in charge permit any work to be finished by
plastering mortar on concrete which has set, but should it be-
come -necessary at any time to refinish a surface which has
set, it shall be picked off so that at least 3 inches of mortar
can be added, and the surface of the old concrete shall be
roughened and thoroughly wet before new material is added,
such new material being mortar as specified for facing.

Layers of concrete shall be kept truly horizontal, and if,
for any reason, it is necessary to stop work for an indefinite

236 HANDBOOK FOR CEMENT USERS.

period, it shall be the duty of the inspector and of the con-
tractor to see that the top surface of the concrete is properly
finished, so that nothing but a horizontal line shall show on
the face of the concrete, as the joint between portions of the
work constructed before and after such period of delay. If,
for any reason, it is impossible to complete an .entire layer,
the end of the layer shall be made square and true by the use
of a temporary plank partition. No irregular, wavy or slop-
ing lines shall be permitted to show on the face of the con-
crete work as the result of constructing different portions of
the work at different periods, and none but horizontal or ver-
tical lines shall be permitted in such cases.

Where concrete is to be put into a foundation below water
level, all water shall as far as possible be removed from the
excavation. If it is impossible by means of the ordinary
pumping facilities to control the flow of water, the excava-
tion may be taken out in sections, and the concrete may be
placed in the foundation, section by section. Special care
should be taken to ram thoroughly the bottom layer of con-
crete, and to remove all mud and clay from the vertical face
of each section of concrete, as additional sections are exca-
vated and prepared for addition of concrete work. Where
the foundation is soft, as, for example, where piles are used,
either fine or coarse broken stone may be spread over the
bottom of the excavation and thoroughly rammed into the
earth before putting in any concrete. In no case shall a dry
mixture of sand, cement and crushed stone be put into a foun-
dation without thorough mixing. Wher-\ strata of gravel and
sand permit the entrance of water into the foundation with
such freedom that small sections of the same can not be exca-
vated and pumped out for concreting, a grout of pure cement
or of a mixture of cement and 1 or 2 parts of sand may be in-
jected through a pipe into the loose gravel and sand in the
bottom of the foundation ; this work being done while the ex-
cavation is filled with water. The pipe through which this
grout is passed should be pushed a few inches below the
surface of the gravel, and a bucketful or more of grout should
be poured down through the pipe, the pipe being then moved
1 or 2 feet and the operation repeated, distributing the grout
over the whole area of the bottom to be thus cemented and
the work then should be allowed to stand for 24 to 36 hours.
It will generally be found that the sand and gravel will be
converted into a water-tight concrete, permitting the pump-
ing out of the excavation.

Where it is impossible to complete parapet walls, copings,
etc., on account of stringers or other wood or iron work nee-

SPECIFICATIONS FOR THE USE OF CEMENT. 237

essary to maintain structures over which tracks are in use,
all work shall be finished to horizontal and vertical lines,
and with surfaces filled with mortar, so that when possible to
complete the concrete work the joint between the new and
the old work shall show nothing but straight, level and ver-
tical lines.

Expansion Joints. Where masonry structures are more
than 100 feet in length, such provision for expansion joints
shall be made as may be specified by the engineer of bridges
or his assistants. Generally in the construction of large
arches, or of smaller, long concrete arches, the work shall be
subdivided into sections of approximately 25 feet in length,
each section being separated from the adjacent one by a ver-
tical joint extending entirely through the bench walls, arch
rings, etc.; but the foundation work shall be stepped as pre-
viously explained, and made in one continuous monolithic
mass. Temporary vertical partitions shall be put into the
molds, against which the concrete shall be thoroughly
rammed, where arch culverts are subdivided into short
lengths as above specified, these partitions being removed as
each section is completed, and the next adjacent section being
rammed against the concrete already constructed and set.
The joints thus made shall not be flushed with mortar, nor
shall any attempt be made to make the fresh concrete adhere
to the older work, but a small beveled strip of wood shall be
set in the angle next to the temporary partition so as to make
a "V" groove, defining the joint and leaving a depth of, say,
%-inch on the finished face of the work, it being the intention
that any contraction shall open or that settlement shall effect
a sliding action at such vertical joints, rather than to break
up the concrete in the separate sections.

'Pointing. After the molds are removed, if there should be
found any small pits or openings on the exposed faces of the
concrete (or if bolts are used for securing the molds, the ends
of which are removed, leaving small holes), all such holes, pits
or porous places shall be neatly stopped with pointing mor-
tar, made of equal parts of cement and sand and mixed in
small quantities to be used before the same shall set. Al-
though it has not been specified to use a facing of mortar for
such masonry as is to be permanently buried or covered by
earthwork, such masonry shall not be constructed and left
with pores and honey-combed surfaces. All such pores and
openings shall be stopped with a pointing mortar, composed
of 1 part of cement and 2 parts of sand, the same to be neatly
filled into all openings and smoothly finished, in advance of
any filling against such work.

238 HANDBOOK FOR CEMENT USERS.

Name Plate and Date. A name plate and date shall be fur
nished by the contractor and put upon one piece of masonry
at each bridge or job constructed by him, such plate to be of
brass or copper or other durable metal, furnished with bolts
or projections on the back to be buried in the concrete and to
secure it firmly to the same, and having on it the contractor's
name and the date of the year in which the concrete work is
constructed. These plates should be placed upon the parapet
walls of abutments, concrete arches and pipe culverts, and
upon the ends of the bridge seats of piers, where they can be
plainly seen and easily read. These should be set as the con-
crete work is finished and should be level with the surface of
the same.

Extra Work. It is the intention of the foregoing specifica-
tions that work of all kinds shall be done by unit prices. It
shall be paid for at rates per unit of measure of the several
kinds of work required. Wherever, in the judgment of the
engineer in charge, such prices are unfair to the contractor,
the conditions shall be fully explained to the engineer of
bridges, whose permission shall be obtained in writing for all
extra work to be done. .Generally such work shall be done at
the actual cost, and the contractor shall be allowed 10 per cent,
in addition, to cover the superintendence, the use of tools, etc.
No other rate will be allowed, unless specially provided when
the work is ordered.

A daily report of forces employed and material used in all
extra work shall be made by the foreman on the work to the
assistant engineer or inspector in charge of the work, who
shall check the same from day to day and settle all disputed
questions as to labor and material used. A return of all such
extra work shall be made by the contractor (or by his fore-
man) at the end of each month, which shall be given to the
engineer or inspector on the work for certification, and shall
be sent to the engineer of bridges, with the estimate of work
done at contract prices, so that the monthly estimate may
cover all work done during the month. In general, all bills for
extra work claimed to have been done by the contractors shall
be rendered monthly and shall be certified to by the engineer
or inspector in charge of the work.

EXTRACTS FROM THE RULES AND INSTRUCTIONS FOR MASONS ON
''COMPANY" WORK OF NEW YORK CENTRAL AND

HUDSON RIVER RAILROAD.

Concrete Mixing. Mix the cement and sand as follows:
Spread about one-half of the sand to be used in a batch of
mortar evenly over the bed of the mortar box, then spread
the cement evenly over the top of the sand, and finally spread

SPECIFICATIONS FOR THE USE OF CEMENT. 239

the remainder of the sand on top. The sand and cement
should then be thoroughly mixed by turning and returning at
least six times with a shovel. The mixture is then drawn to
one end of the box and water poured in at the other end.
Then draw the mixture down to the water with a hoe, small
quantities -at a time, and mix vigorously until there is a good
stiff mortar. Enough water should be used so that the mortar
will work well under the trowel. Then level off the mixture
and spread over it the required amount of broken stone or
gravel, which should be first moistened; then thoroughly mix
the whole mass by turning and returning it with shovels in
rows, at all times preserving the same thickness of the mass,
until the mortar thoroughly fills all the interstices.

A thorough mixture of the ingredients is the first condi-
tion of a good concrete.

A mortar box with detachable sides will be found econom-
ical and convenient for concrete mixing.

Concrete Laying. After the concrete is mixed it should be
quickly laid in sections, in layers not exceeding 8 inches in
thickness; and shall be thoroughly rammed with 2-man ram-
mers, weighing not less than 30 pounds each, until the water
flushes to the surface. It shall be allowed at least twelve
hours to set before any work is laid on it. Concrete mixed
for over one hour will not be allowed in the work.

Forms of timber shall be used wherever necessary to main-
tain the dimensions of the concrete shown on the plans.

Facing Concrete. Concrete for facing old masonry shall
consist of 1 part best quality Portland cement, 2 parts clean,
coarse, sharp sand, and 4 parts of %-inch broken stone, with
outer facing consisting of a mortar of the proportions of one
part Dyckerhoff, Germania, or other approved imported Port-
land cement, to 2 parts clean, coarse, sharp sand of an aver-
age thickness of 1 inch deposited simultaneously with the
backing; to be securely fastened to the old masonry with
anchors and twisted rods as shown on the standard plan.
Use molds as specified below. (American cements are now
used.)

Molds. The concrete shall be deposited in molds made
from dressed matched siding firmly held in place by exterior
braces, posts, etc.; or by bolts or ties so made as to be re-
moved from the work and leave no iron within 1 inch of the
face of the finished work. The siding shall be set truly hori-
zontal, with butt-joints truly vertical and with the faces
against which the concrete is to be placed, dressed, and set
to true planes, and covered with soft soap or other approved
material to prevent "sticking." After the molds are re-

240 HANDBOOK FOR CEMENT USERS.

moved, any open or porous places shall be neatly stopped with
pointing mortar; and if so directed by the engineer, the ex-
posed faces of the work shall be washed with neat Portland
cement to give a uniform, smooth finish to the exposed sur-
faces.

Temperature Changes. In large structures, provision for
expansion and contraction shall be made by tarred paper,
vertical joints not less than 50 feet apart extending through
the mass. Wet down all outside surfaces each day until the
expiration of two w r eeks after the entire work is completed.

SPECIFICATIONS FOR CONCRETE OF THE CHICAGO AND ALTON
RAILWAY COMPANY.

Concrete will, in general, consist of a matrix of cement
mortar and an aggregate of broken stone or gravel, or a com-
bination of broken stone and gravel.

Materials. The cement used shall conform to the C. & A.
Ry. Co. specifications.

The sand shall be practically free from clay, loam, sticks,
leaves and other foreign substances, but may contain occa-
sionally pieces of small gravel. The sand shall be so coarse
that not more. than 40 per cent, of it will pass through a No. 50
sieve, 50 meshes per linear inch.

The broken stone shall be of sound lime stone, which shall
be composed of angular fragments, no piece of which shall
exceed two inches in greatest dimension. It shall be clean
and free from dust, dirt or other foreign matter, but may
consist in part of fine screenings and medium-sized pieces,
the intention being to take all of the product of the crusher
except the fine dust.

The gravel shall be clean and free from dust, dirt and other
foreign substances, and shall contain no stones over two inches
in diameter. When gravel containing considerable quantities
of sand is used, several trials must be made to determine the
proportion of sand it contains that will pass through a No. 4
screen, and a corresponding deduction shall be made from the
sand used in making the mortar, so that the final proportions
of the cement and sand in the complete mixture shall be as
specified for mortar.

Only the gravel remaining after screening out the sand
shall be treated as aggregate during the experimenting for
voids referred to later.

Proportions. In general, the following proportions will be
used:

In footing courses and foundations below frost line the
matrix or mortar shall be 1 part packed natural cement to
parts loose sand.

SPECIFICATIONS FOR THE USE OF CEMENT.

241

In the body of the structure the matrix shall be 1 part
packed Portland cement to 3 parts loose sand.

When the cement is packed in barrels the barrel shall be
the basis of measure for the sand and also for the aggregate.
But when the cement is packed in sacks, 3% cubic feet shall
be considered a barrel of sand or aggregate.

When the aggregate is composed of both broken stone and
gravel they shall be mixed in such proportions (to be deter-
mined by experiment) as will give the ieast per cent, of voids
when mixed.

In general, the amount of mortar mixed with the aggregate
shall be at least 10 per cent, more than the voids in the loose
aggregate, which the engineer shall determine by experiment.

In experimenting for voids, where possible, the method of
weights shall be used, assuming the weight of dry gravel and
broken stone to be 165 pounds per solid cubic foot, and exclud-
ing from the aggregate the sand which occurs in the gravel.

In copings and the top foot in depth of parapet walls the
concrete shall contain about y 8 less aggregate for a given
amount of mortar than the standard mixture for the body of
the structure.

The amount of mortar made by given amounts of cement
and sand shall also be determined by experiment, but in the
absence of such experiments for special cases the following
may be used as an approximation, the units of cement being
a barrel of 380 Ibs. net for Portland, and 265 Ibs. net for nat-
ural cement.

PROPOR-
TIONS.

CEMENT.

SAND.

RESULTING
MOKTAR.

Portland Cement

1 to 1
1 to 2
) to 3

1 bbl.
1 bbl.
1 bbl

3.5 CU. ft.

7.0 cu. ft.
10.5 tu. ft.

6 CU. ft.

8.0 cu. ff
10.7 cu. ft.

Natural Cement ....

1 to 1
1 to 1 5

1 bbl.
1 bbl

3.50 cu. ft.
5 25 cu ft

5.7 cu. ft.
6 9 cu ft.

J to 2

Ibbl.

7.00 cu. ft.

7.8 cu. ft.

When necessary to use concrete without making the above
experiment for voids in the aggregate, the following propor-
tions shall be used unless others are specified :

Footings 1 bbl. natural cement to 5*4 cubic feet loose
sand to 17 cubic feet loose aggregate.

In the body of the structure, 1 bbl. Portland cement to 10.5
cubic feet loose sand to 25 feet loose aggregate.

For copings and the upper foot of parapet walls, 1 bbl.

242 HANDBOOK FOR CEMENT USERS.

Portland cement to 10.5 cubic feet loose sand to 22 cubic feet
loose aggregate.

In all cases the proportions shall be reduced to such a
basis that they can be stated as follows in terms of the actual
materials as delivered on the ground for use :

One bbl. cement to cubic feet sand to

cubic feet gravel to cubic feet broken stone.

The proportions so stated, together with descriptions of all
experiments leading thereto, shall be submitted to the chief
engineer for approval, and after approval shall be followed in
measuring the materials until there is reason to change them
through change in condition of materials received. The neces-
sity for such change shall be determined by the engineer and
approved by the chief engineer.

Mixing. Great care must be used to get even mixing, and
preference will be given to approved mechanical mixers.

When the mixing is done by hand, the sand shall be spread
first and the cement on top of it, and they shall be mixed dry
by turning with shovels or hoes, until the mixture is of uni-
form shade and free from lumps of sand or cement. Water
shall then be applied by sprinkling the mixture while turning
it. The mixing shall then continue until the mortar becomes
of a uniform dampness throughout. It shall then be spread
out, and the aggregate having been thoroughly wet down,
shall be spread upon the mortar and the two turned together
from three to five times, or until the mixture appears to be
perfectly uniform throughout.

The aggregate shall be frequently wet down, especially in
warm weather, so that the pieces of broken stone and gravel,
when mixed with the mortar, will be saturated and will not
absorb water needed for the compacting and setting.

Sufficient water shall be used in the mixing to insure the
closing of all voids by a moderate amount of ramming. This
can only be insured by slight quaking during the ramming.

Placing. The concrete shall be thoroughly rammed in lay-
ers of from six to nine inches, as directed by the engineer.
The tamping tools shall be at least six inches square at the
bottom, and the bottoms shall be kept clear of hardened mor-
tar so as to pack the concrete with flat surfaces. The layers,
or courses, must be horizontal and should be placed contin-
uously over the whole area within the forms. Where this is
impracticable, and one or two benches are necessary, care
must be taken to prevent the appearance on the face of the
structure of any irregular lines due to the concrete in these
benches setting before they are covered with fresh concrete.

When permitted to set before being covered, footing
courses must be left rough- on top to give a good hold for the

SPECIFICATIONS FOR THE USE OF CEMENT. 243

superimposed concrete. This shall, at the discretion of the
engineer, be accomplished by embedding pieces of plank in the
top of the footing course, to be removed after the concrete
has set, leaving depressions. Beveling the edges of these
planks will facilitate their removal.

This method, or other methods approved by the engineer,
shall be used whenever it is necessary to leave work unfin-
ished over night or for a longer time. When work is resumed
the surface of the concrete already set shall be thoroughly
wet down and washed over with a thin mortar of 1 part
cement to 1 part sand just before depositing the next layer of
concrete. Work shall never be stopped within two feet of the
top of the coping, unless absolutely necessary.

All mortar shall be mixed fresh for the work in hand, and
no mortar or concrete shall be used which has begun to set
before tamping in its final position.

Exposed Surfaces. All faces to be exposed or liable to be-
come exposed in the finished structure shall be given a good
smooth surface by working the mortar and finer concrete next
to the form with a shovel or spade. No plastering on any ex-
posed surface after forms are removed, will be permitted,
and pointing of holes in the face must be reduced to a min-
imum by the above method.

Top surfaces, both horizontal and inclined, shall be finished
by covering with one-half inch of mortar composed of 1 part
cement to 2 parts sand, and placed before the concrete under
it has begun to set. It shall be rubbed smooth.

Vertical Joints. In long, continuous concrete structures
liable to considerable changes of temperature, such as retain-
ing walls, provision shall be made for expansion and contrac-
tion. This shall be accomplished by the use of temporary
vertical partitions extending from the footing course to the
top and dividing the structure into sections approximately
25 feet long. Each section shall be finished to the top before
the adjoining section is started, and no attempt shall be made
to make the sections adhere to each other, so that when cold
contracts the structure it will open up slightly in these ver-
tical joints, and not in an irregular crack.

A plank shall be spiked vertically to the face of the parti-
tion against which the concrete is to be rammed, so that a de-
pression will be formed in the end of the section, giving the
effect of tongue and groove joints in the finished wall.

Protection of Surface. When work is stopped, either be-
fore or after completion, the. surf ace of the concrete recently
placed shall be wet down and covered in some manner accept-

244 HANDBOOK FOR CEMENT USERS.

able to the engineer to protect it from the weather and from
rapid drying out through evaporation.

Footings. The laying of concrete below water line, or in
wet ground, shall be protected by cofferdam or sheeting in
manner acceptable to the engineer, and if in his judgment it
is demanded, Portland cement concrete shall be substituted
for natural cement concrete.

Cold Weather. When it is necessary to make concrete in
freezing weather only Portland cement concrete will be used,
and the materials shall be heated by steam or otherwise, and
hot water used in the mixing.

In general, less water shall be used for mixing in cold than
in warm weather, and in no case shall a surplus of water be
allowed to accumulate and freeze on top of a layer of concrete
and then be covered up with more concrete before thaw-
ing out.

Forms. Forms shall be constructed so that their inner
surfaces will conform strictly to the dimensions called for by
the plans of the structure. The plank used for exposed faces
shall be dressed on both edges, and at least on one face to a
uniform thickness, and such care shall be used in construct-
ing the form that the finished concrete structure will present
a smooth, unbroken surface.

The facing plank shall be of sufficient thickness and the
uprights sufficiently strong and frequent to prevent any
springing of the form when the concrete is rammed in place.

Where rods are used to hold the front and back of the form
together they may left in the concrete if a sleeve nut is
used at least three inches back from the face, and the outer
end of the rod removed, and the hole rammed full of mortar 1
part cement to 3 parts sand.

Provision shall be made for rounding off all angles between
exposed surfaces by using in the form small quarter-rounds
and coves to fill these angles.

The walls of the wooden forms shall be kept wet during the
progress of the concrete work.

Forms shall not be removed sooner than directed by the
engineer.

Interpretation. The requirements of these specifications
in any particular are subject to modification by the chief
engineer, who will decide all questions as to their interpreta-
tion.

NEW YORK RAPID TRANSIT RAILWAY.

The proportions of mortar by volume are for the various
classes of work as follows :

SPECIFICATIONS FOR THE USE OF CEMENT. 245

Brick masonry: 1 portion of Portland cement and 2 por-
tions of sand.

Column footing stones : 1 portion Portland cement and 2
portions sand.

Stone masonry: 1 portion Portland cement and 2 l / 2 por-
tions of sand.

Rubble masonry: 1 portion natural cement and 2 portions
sand.

Pointing: 1 portion Portland cement and 1 portion sand.

The requirements for concrete are as follows :

The concrete shall be composed of sound, clean, screened
all dirt and dust, and mixed together with the proportion of
mortar specified below. The broken stone or gravel used for
concrete for the finishing floor of the railway, must not exceed
gravel or sound broken stone, or a mixture of both, free from
1 inch at their largest diameter. For all other concrete the
maximum diameter for broken stone or gravel, unless specif-
ically permitted by the engineer, must not exceed in any direc-
tion 2 ins., with a minimum diameter of %-in. In all concrete
where the thickness is 30 ins. or more, the contractor may
imbed in the same broken pieces of sound stone whose great-
est diameter does not exceed 12 ins. and whose least diameter
or thickness is not less than % the greatest diameter. These
stones shall be set by hand in the concrete as the layers are
being rammed, and so placed that each stone is completely
and perfectly bedded. No two stones are to be within six ins.
of each other and no stones within 4 ins. of an exposed face.

The proportions of mortar and stone used in making con-
crete shall be as follows : Concrete in arches of roof and side
walls, where the thickness does not exceed 18 ins., 1 portion
Portland cement, 2 portions sand, 4 portions stone. Concrete
in side walls or tunnel arches, where backing is rock in place,
1 portion Portland cement, 2% portions sand and 5 portions
stone. Concrete in foundations in wet ground, where thick-
ness, exclusive of finishing floor concrete, does not exceed 24
ins., 1 portion Portland cement, 2 portions sand, 4 portions
stone. Concrete in foundations in wet ground where thick-
ness, exclusive of finishing floor concrete, exceeds 24 ins., 1
portion Portland cement, 2% portions sand, 5 portions stone.
Concrete in foundations in dry ground, 1 portion Portland
cement, 2% portions sand, 5 portions stone. Concrete in
foundations, where on rock, if not exceeding 12 ins. in thick-
ness, 1 portion Portland cement, 2% portions sand, 5 portions
broken stone; if exceeding 12 ins., 1 portion Portland cement,
3 portions sand, 6 portions broken stone.

(Note. If the rock is dry, natural cement may be substi-

246 HANDBOOK FOR CEMENT USERS.

tuted for Portland cement in above, but increasing the quan-
tity of cement used 30 per cent..) Concrete in mass, such as re-
taining walls, or backing of masonry retaining walls, in dry
ground, 1 portion natural cement, 2y 2 portions sand, 5 por-
tions stone. If such retaining walls or backing are in wet
ground, or subject to extraordinary strain, then Portland ce-
ment shall be substituted for natural..

The broken stone or gravel shall be spread on a platform
sprinkled with Water, and then thoroughly mixed with the
mortar in the proportions as specified above. Machinery for
the mixing of concrete may be used if approved by the engi-
neer. The concrete shall be laid immediately after mixing
and be thoroughly compacted throughout the mass by ram-
ming. The amount of water used in making concrete shall
be approved by the engineer. The concrete shall be allowed
to set for 12 hours, or more, if so directed, before any work
shall be laid upon it ; and no walking over or working upon it
shall be allowed while it is setting. Before laying concrete on
rock surfaces the latter shall be swept clean of all debris and
dirt. Whenever it becomes necessary to lay fresh concrete
next to or on top of concrete in which the mortar has already
set, the surface of the old concrete shall be well washed, and
a thin layer of clear cement shall then be spread over it imme-
diately previous to the laying of the fresh concrete. Suitable
molds shall be provided by the contractor to support the con-
crete while being rammed in the walls or roofs. These molds
shall be immediately replaced by new ones as soon as they
commence to lose their proper shape. Before being used they
shall be carefully cleaned of cement and dirt and shall present
to the concrete on the surface afterwards exposed to sight
a perfectly smooth surface, to be obtained by covering each
portion of the molds with sheet metal, or by carefully planing
the wood and coating the face of the same with black oil. In
no case on an exposed surface of the concrete must the joints
of any component pieces of the mold, nor the grain of the
wood, be visible. The molds shall be set true to line, firmly
secured, and be so tight as not to allow water in the mortar
to escape. They shall remain in place until the concrete is
thoroughly set/and in event of pressure coming at once on
the concrete, such additional time as the engineer may direct.
On removing the molds, if any voids or irregular connections
with the steel framework are discovered, such defective work
shall be cut out and filled with a rich concrete or mortar, in
such proportions and in such manner as the engineer may
direct.

SPECIFICATIONS FOR THE USE OF CEMENT. 247

MAINTENANCE OF WAY ASSOCIATION.

The American Railway Engineering and Maintenance of
Way Association has adopted specifications for concrete from
which the following points are abstracted :

(1) Forms shall be well built, substantial and unyielding,
properly braced or tied together, by means of wire^or rods,
and shall conform to lines given.

(2) For all important work the lumber used for face work
shall be dressed on one side and both edges to a uniform thick-
ness and width, shall be sound and free from loose knots, and
secured to the studding or uprights in horizontal lines.

(3) For backings and other rough work undressed lumber
may be used.

(4) Where corners of the masonry and other projections
liable to injury occur, suitable moldings shall be placed in the
angles of the forms to round or bevel them off.

(5) Lumber once used in forms shall. be cleaned before being
used again.

(6) The forms must not be removed within 36 hours after
all the concrete in that section has been placed. In freezing
weather they must remain until the concrete has a sufficient
time to become thoroughly set.

(7) In dry but not freezing weather, the forms shall be
drenched with water before the concrete is placed against them.

The specifications require that the concrete shall be of such
consistency that when dumped in place it will not require much
tamping. It shall be spaded down and tamped sufficiently to
level off, and the water should rise freely to the surface.

The surface finish is described thus :

After the forms are removed, which should be as soon
as possible after the concrete is sufficiently set, any
small cavities or openings in the face may be neatly
filled with mortar, if necessary in the opinion of the
engineer. Any ridges due to cracks or joints in the lumber
shall be rubbed down with a chisel or wooden float. The entire
face may then be washed with a thin grout of the consistency
of whitewash, mixed in the same proportion as the mortar of
the concrete. The wash should be appplied with a brush. The
earlier the above operations are performed the better will be the
result.

In the discussions it appeared that expansion joints are
needed at lengths of about 30 feet, and that with proper care
in the selection of lumber and in constructing the forms it may

248 HANDBOOK FOR CEMENT USERS.

not be necessary to go to further expense in finishing the faces
of concrete work after removing the forms.

Freezing Weather. Ordinarily concrete to be left above the
surface of the ground will not be constructed in freezing wea-
ther. Portland cement concrete, however, may be built under
these conditions by special instructions. In this case the sand,
water and broken stone shall be heated, and in severe cold salt
shall be added in the proportion of about 2 pounds per cubic
yard.

Reinforced Concrete. Where concrete is deposited in con-
nection with metal reinforcing the greatest care must be taken
to insure the coating of the metal with cement, and the thor-
ough compacting of the concrete around the metal. Wherever
it is practicable the metal should be placed in position first.
This can usually be done in the case where the metal occurs
in the bottom of the forms by supporting the same on trans-
verse wires, or otherwise, when the bottoms of the forms can
be flushed with cement mortar, so as to get the mortar under
the metal at the same time, and the concrete deposited im-
mediately afterward. The mortar for flushing the bars should
be composed of one part cement and two parts sand. The
metal used in concrete shall be free from dirt, oil or grease.
All mill scale should be removed by hammering the metal, or
preferably by pickling the same in a weak solution of muriatic
acid. No salt shall be used in reinforced concrete.

In the discussions attending the adoption of the foregoing
clauses, it appeared that a considerable amount of reinforced
concrete work has been done recently on railroads centering
ing in Chicago during freezing weather. It was stated that
where the materials are properly heated, as specified above,
the mass of concrete does not fall to a freezing temperature
for about 24 hours later even when the temperature is below
zero during the period. It was suggested by a chemist present
at the meeting that where the metal is pickled in acid it should
be thoroughly washed afterward so as to remove the acid be-
fore depositing the concrete.

HEAVY MONOLITHIC CONCRETE MASONRY.

From a description given in a paper by Jas. 0. Long before
the Western Society of Engineers, the following specifications
and instructions regarding the construction of canal lock ma-
sonry on the Illinois and Mississippi canal are taken :

Proportions and mixing of concrete:

SPECIFICATIONS FOR THE USE OF CEMENT. 249

Proportions and ingredients are measured by volume, and the
numbers of cubic feet given below represent the quantities to
be used for each charge of concrete put into the mixer.

Portland cement concrete shall in general consist of :

Portland cement 1 part 5 cu. ft. 5 sacks.

Gravel 4 parts 20 cu. ft.

Broken stone 4 parts 20 cu. ft.

For the wall supporting the upper gate and in the vicinity
of the quoins the concrete shall consist of:

Portland cement 6 cu. ft. 6 sacks.

Gravel 20 cu. ft.

Broken stone 20 cu. ft.

Natural cement concrete shall consist of :

Natural cement 2 parts 8 cu. ft. 4 sacks.

Gravel 5 parts 20 cu. ft.

Broken stone 5 parts 20 cu. ft.

Facing material shall consist of, by volume:

1 part Portland cement.

3 parts Torpedo sand passing No. 5 sieve.

The piles of gravel and broken stone shall be kept thoroughly
sprinkled with water to clean surface of dust and to prevent
absorption by the dry stone of the water used in mixing the
concrete.

When delivered in bags, each bag of cement shall be emptied
directly into the charging box, as the division of a barrel of
cement into several bags diminishes the chances of injurious
effect of a defective barrel, and hence the usual requirements
of drawing charges from a mixture of five or more barrels may
be dispensed with. When delivered in barrels this latter re-
quirement will be observed.

All bags and sacks shall be carefully preserved for return to
the dealer furnishing cement, in order to secure to the United
States the rebate thereon, to be deducted from subsequent bills
for cement.

The proper measures of ingredients shall be emptied into the
charging box in the following order : 1st, gravel, 2d, cement ;
3d, broken stone; 4th, water.

Enough water shall be added to make the concrete cohere
after a thorough mixing. A greater degree of plasticity than
that possessed by damp sand is required. The object is to have
the consistency such that a thorough ramming will bring water
to the surface. The mass of concrete should not quake on ram-
ming; incipient quaking marks the limit, and any excess of
water in one charge may be corrected by making the next charge
a little dryer. The proper amount of water can be determined
only by experience, and must be varied from time to time to

250 HANDBOOK FOR CEMENT USERS.

suit the conditions of the weather and the ingredients. It is
very important that Portland cement shall have sufficient water
for its complete hydration. Natural cement requires less water
for hydration than Portland.

The contents of the charging box shall be dumped immedi-
ately into the cubical mixer, which shall be revolved for not
less than two minutes at a rate not exceeding nine revolutions
per minute. The product is improved by long mixing, and all
the time less than period required for initial set available be-
tween deliveries required at the forms should be utilized for
extra turns to the mixer. The facing material shall be mixed
by hand, and a very small gang will be able to keep the forms
supplied. For a facing of uniform thickness of 2 inches, about
70 cubic yards only will be required for a lock, or about 3 l / 2
cubic yards to each section. A close watch must be kept of the
quantity used, and the above limit must not be exceeded.

Depositing and ramming concrete :

Each lock shall be built in sections, averaging about 20 feet
in length, making 10 sections to each wall. The planes of divi-
sion between sections shall be at right angles to the axis of
the lock, and are indicated on drawing furnished from this
office.

Each section shall be a monolithic mass of concrete built
continuously from the bottom to completion without horizontal
joints. The sections shall be filled with horizontal layers about
6 inches thick, each layer to* be deposited before the "initial"
set of the previously deposited layer and then be well rammed
in place.

The vertical planes of division between sections shall be made
by transverse bulkheads built in the forms, and at each bulk-
head a dovetail or recess shall be made for the interlocking of
adjacent sections, the dovetails reaching from foundation to
one foot below the coping of the sections.

Alternate sections shall be 'built first, then the bulkheads
shall be removed and the remaining sections filled with concrete.

Before .beginning a section, its foundation shall be swept
clean with wire brooms and covered with a wet layer one inch
thick of 1 to 1 cement mortar to make a close joint between the
wall and the foundation.

The walls of the wooden forms shall be kept well wet during
the progress of the concrete work to prevent their absorption
of water from the newly placed concrete.

The lowest step or thickest part of the lock walls shall con-
sist of not less than two feet of Portland cement concrete next
to the face of the wall and a backing of natural cement concrete.
All other walls or parts of walls shall be of Portland cement
concrete.

SPECIFICATIONS FOR THE USE OF CEMENT. 251

The exposed faces shall consist of Portland cement and tor-
pedo sand, 1 to 3. The thickness of facings shall not exceed
iy 2 inches nor be less than % inch.

The facing and backing must go on simultaneously in the
same horizontal layers. In order to gauge the thickness of the
facing accurately, a light board or diaphragm of thin metal
with convenient handles shall be set on edge parallel to and
1% inches from the front wall of the forms. The facing ma-
terial shall be deposited in the space between this board and
the form. The concrete of the backing shall then be deposited
and spread against the back of the board, which may then be
withdrawn and the whole mass thoroughly rammed" so as to
bond the facing and backing by destroying the surface of de-
marcation between them ; but no stone must be forced nearer to
the front wall of the form than % inch. No attempt shall be
made to secure a definite surface between the Portland and
natural cement concrete in the lowest step of the lock walls,
but they shall be thoroughly bonded, blended and interlocked
one into the other by long lap or splice joints in every layer de-
posited.

The top 6 inches of wall should have no broken ston'e 1 part
Portland cement, 4 parts gravel with large stones cast out.
The top of coping for not more than 1 inch should be placed as
soon as practicable upon this gravel concrete, mixed 2 parts
cement and 3 parts torpedo sand, of consistency of mason's
mortar, but quite wet, not stiff. It should be dumped and rap-
idly spread over the concrete and roughly finished. It should
then be left to begin to stiffen and "shed its water" ; but before
its "initial set," and while still plastic, it should be finally fin-
ished smooth, well pressed and compacted into a firm, smooth
coat and slightly crowned in the center.

As soon as the setting is sufficient to stand it, the coping
should be well sprinkled with water, and covered from air and
sun for several days, keeping it well wet until set hard.

The facing and coping shall show a smooth, dense surface
without pits or irregularities. This is most likely to be se-
cured by thorough and systematic ramming.

Concrete shall not be laid in water nor exposed to the action
of water until thoroughly set. Concrete or mortar shall not
be made when the temperature is lower than 35 degrees Fah-
renheit in the shade, nor when rain is falling on it. All con-
crete work shall cease November 20, and not be resumed before
April 1. Forms and molds must be left in position for not
less than four days after concrete is deposited. Freshly depos-
ited concrete shall be protected from the direct rays of the sun
and from wind by boards or tarpaulins, and as soon as a section
of wall is completed the exposed coping must be covered with a

252 HANDBOOK FOR CEMENT USERS.

thick layer of wet sand, and the whole mass of wall must be
kept sprinkled until the concrete is thoroughly set.

Twenty-one Vocks were built as dbove. They are 170 feet
long between gates, 35 feet wide in lock chamber, and have an
average lift of 9% feet. They contain, exclusive of foundations,
an average of 2,567 cubic yards of concrete masonry to each
lock, which cost f 6.78 per cubic ?tard.

The average time consumed in placing this concrete masonry
was 10 days for each lock. The longest time was 13 days and
the shortest time was 8 days. The average amount of concrete
placed per day was 256.7 cubic yards, and the largest average
per day on any one lock was 320 cubic yards.

A CONCRETE BLOCK DAM.

The following is an abstract of the concrete portion of the
specifications for the dam of the Lynchburg, Va., water works,
built of concrete blocks:

Portland cement concrete shall be composed of one part Port-
land cement, two and one-half parts sand and four and one-
half parts ballast. Hydraulic cement concrete shall be com-
posed of one part hydraulic cement, two parts sand and four
parts ballast.

The concrete in the dam shall be built up in large blocks,
each block being formed in place and completed at one opera-
tion. The blocks on the upstream face of the dam, the crest,
and the downstream face shal/ be formed of Portland cement
concrete. The blocks in the hart of the dam shall be formed
of natural hydraulic cement concrete.

Each block of concrete shall be built between substantial tim-
ber forms securely braced in place. The surfaces of the forms
against which the concrete is to be deposited shall be smooth,
laid close together and spiked to the vertical posts or frame-
work. The lumber need not be planed. The vertical grooves
in the concrete blocks shall te formed by securing 2xlO-inch
planks against the interior surfaces of the forms. The hori-
zontal tongues on the tops of the blocks shall be formed be-
tween pioperly prepared molds laid upon the surface of the
wet concrete after bringing the same up to the proper level,
and the concrete forming the tongue shall be deposited in
place before the concrete underneath shall have set, and
shall be thoroughly tamped and bonded thereto. All vertical
and horizontal tongues and grooves shall be continuous
throughout the length and depth of each block of concrete.

The b/ocks forming the upstream face of the dam shall be
laid alternately as headers and stretchers, the depth of the
courses being 5 feet. The stretchers shall be 2 feet 6 inches deep

SPECIFICATIONS FOR THE USE OF CEMENT. 253

on their beds and 6 feet long, and the headers 3 feet wide and 4
feet 6 inches long.

The blocks forming the heart of the dam shall be, in general
dimensions, not larger than about 10 feet by 15 feet, but shall
be of irregular rectangular shapes, with horizontal beds and
vertical sides. The beds of the large blocks shall be stepped,
in a manner to break joints with other continguous blocks, so
as to give a thorough bonding both horizontally and vertically.
On the tops of the blocks in the interior of the dam the tongues
shall be run approximately parallel to the upstream face of the
dam, shall not be less than 6 inches high and shall vary in width
from 12 inches to 24 inches, according to the way the blocks
interlock. In horizontal planes the large blocks shall be off-
setted in the general manner shown on the plans, but the actual
form of each block will depend upon the shapes of those in the
lower layers, the forms being arranged so that thorough bond-
ing and breaking of joints will be secured.

The concrete shall be deposited in the blocks in the following
manner : Over a portion of the prepared bottom a layer of con-
crete about 6 inches thick shall be spread, leveled off and thor-
oughly tamped ; upon this shall be lowered a large stone, a pro-
per mortar bed having been prepared to receive it. The stone
shall be jolted and worked down to secure a perfect bed, and
shall be raised and rebedded as often as necessary to secure
a perfect bedding. Another large stone shall be similarly
bedded, and the operation kept up until the entire area of the
bottom of the block is covered with concrete. The selecting
and placing of the large stones shall be so done that no stones
will be nearer together, or nearer to the forms, than 6 inches at
any place. The spaces between the stone and forms shall then
be filled with concrete in layers about 9 inches thick, each
layer being thoroughly and solidly tamped to secure perfect
bonding with the stones and forms.

During the placing of the concrete around the stones the lat-
ter shall be kept wet by sprinkling with clean water, and all
stones, before being placed in the blocks, shall have been
roughly trimmed up to remove all feather edges, splinters and
checked portions, and shall have been washed clean with clean
water to remove all dirt, dust and loose particles. None
but sound quarry stones, roughly rectangular in shape, free
from checks, cracks, decomposed faces, sliver edges, and other
undesirable qualities, shall be used.

The sizes of the stones will vary according to the yield of the
quarry, but it is desirable to use stones as large as can be
economically gotten out, transported and handled. Their
sizes will depend somewhat upon the quality of their beds, as

254 ' HANDBOOK FOR CEMENT USERS.

the difficulty of forming a good bed joint increases with the
sizes of the stones. The quality of the beds must be good for
materials of this class, and present such even surfaces that,
when lowering a stone into place, there can be no doubt that
the mortar will fill all spaces.

The sizes of the concrete blocks shall be such that each block,
including the tongues on the top therof, can be finished in one
day. Each block, when finished, must have its top surfaces hor-
izontal, comparatively even and smooth, absolutely dense and
compact, with no voids showing between the stones of the con-
crete, and exhibiting a surplus of mortar all over the top.
After each block is completed the forms shall be left in place
until permission to remove them is given by the engineer. The
top of each block shall be covered with boards, canvas, damp
sand and other protective covering, and shall be kept dampened
with water, if so directed by the engineer, until the concrete
has thoroughly hardened and set and there is no longer dan-
ger of drying and cracking. The contractor shall so lay out
and arrange his work that each block shall have had at least
one week to set before another block is joined to it, or built
upon it, to allow for the change in volume following the setting
of the concrete.

Eefore starting a new block between those already con-
structed, the contractor shall remove all feather edges, and all
portions of the work that may accidentally have been injured,
sweep up all dust and debris and thoroughly drench, with clean
water, the surfaces of the old concrete against which the new
work is to join. He shall then paint over all vertical and hori-
zontal joints in the surrounding blocks with a thick wash com-
posed of equal parts of Portland cement and slaked lime, the
lime, before using, having been slaked for at least fourteen days
and having been run through a fine screen to remove lumps and
particles of unburned stones. This wash shall be applied in a
strip about 8 inches wide, 4 inches each side of and covering
the joint, put on thickly with short handled brooms or brushes,
and thoroughly filling all corners and angles.

Wing walls either side of the spillway, the walls of the gate-
chamber and the parapets of the main dam are to be reinforced
with twisted square steel rods. The downstream edge of the
crest of the spillway will be of cut stones doweled together with
1-inch steel pins 6 inches long and anchored to the concrete by
means of %-inch twisted square steel rods bent around the
dowels into the form of a long U and extending 6 to 7 feet into
the concrete. The treads of the spillway steps will be of sound
granite blocks 18 to 27 inches deep and large enough to extend
about 2 feet under the next step above. Exposed faces of these

SPECIFICATIONS FOR THE USE OF CEMENT. 255

blocks are to be rough pointed and the joints between them are
not to exceed 1 inch.

The top of the main dam is to be 10 feet wide at an elevation
8 feet above the spillway crest, and at both downstream and
upstream faces parapets will rise 2 l / 2 feet above the ordinary
full-reservoir level. Each parapet is to be reinforced near its
top by a 1-inch steel rod extending its entire length. The sur-
faces of the parapets and of the top of the dam between them,
the top of the spillway and the tops of the steps of the wing
walls, will be finished with a 1-inch coat of 1 to 1 Portland
cement mortar, applied to the concrete before the latter has
set and troweled down hard and smooth. The coating on the
vertical faces, however, is to be deposited in the forms with the
concrete.

CONQEETE RESERVOIR LINING.

The following from a paper before the New. England Water
Works Association by O. M. Saville, gives the method and the

CONCRETE LINED RESERVOIR, HAVANA WATER WORKS. -

important specifications for lining the Forbes Hill Reservoir
at Quincy, Mass.

The bottom and slopes of the reservoir were lined through-
out with two layers of concrete masonry, separated by a layer
of Portland cement plaster, iy 2 inches in thickness.

256 HANDBOOK FOR CEMENT USERS.

Concrete masonry (Class C), composed of 1 part of Amer-
ican natural hydraulic cement, 2 parts of sand and 5 parts of
stone, was used for the under layer of concrete on the bottom
of the reservoir.

Concrete masonry (Class D), composed of 1 part of Port-
land cement, 2y 2 parts of sand and Qy 2 parts of stone, was
used for the under layer of concrete on the slopes of the
reservoir.

Concrete masonry (Class E), composed of 1 part of Portland
cement, 2y 2 parts of sand and 4 parts of stone, was used for
the upper layer of concrete on the bottom and slopes of the
reservoir.

It was specified that the cement should be properly tested,
that the sand should be of approved quality, and that either
clean gravel, stone or crushed rock should be used in the con-
crete.

None of the stones were to be larger than 2y 2 ins. in their
greatest diameter and those used in the upper layer of the
reservoir lining were limited to iy 2 ins.

The layer of plaster between the concrete layers was put
down in strips about 4 ft. wide and finished similar to the sur-
face of a granolithic walk. This layer was mostly composed
of 1 part Portland cement to 2 parts sand, with a finishing
surface composed of 4 parts cement to 1 part sand. Long
strips of coarse burlap soaked in water were used to keep
this layer wet and cool. In spite of these precautions some
cracks appeared which were grouted before being covered
with concrete. Three gangs, each of a plasterer and helper,
were employed on this work, each gang laying about 700 sq.
ft. per day.

The upper layer of the concrete lining was formed in blocks
about 10 ft. sq. on the bottom of the reservoir and 8x10 on
the slopes. These blocks alternated in both directions, one-
half being first laid and allowed to set. The surface of these
blocks on the slopes was left about 1 in. low and finished with
a layer composed of the same proportions as the balance of
the block, but stone dust, and stone less than %-in. was sub-
stituted for the l^-in. stone. This layer was applied before
the under concrete set and was finished to a firm, smooth
surface, true to the required slope. About 3,850 Ibs. of Atlas
Portland cement were used on the work. The greater part of
this cement came to the worfc in bags. The sand was of ex-
cellent quality, some coming from Avon, Mass., and the rest
from local pits. The best was that which came from a near-
by sewer excavation, where a water-bearing sand stratum was
encountered. The bulk of the stone used in the concrete came

SPECIFICATIONS FOR THE USE OF CEMENT. 257

from the hardpan excavation, and was crushed on the work.
This stone was quite dirty and had to be washed before crush-
ing.

Previous to setting up the crusher about 750 cu, yds. of
gravel stones were used, brought from a local pit. These
were very dirty, also, and needed to be washed.

At first everything smaller than 2y 2 i ns - was used, but it
was found that so great a quantity of dust was coming as to
give the result of adding more sand to the mixture. On this
account the screens were changed and a portion of the dust
discharged into a separate pile, and was later used in the
surfacing of the upper layer of concrete on the slopes. The
stone crushed on the hill weighed about 95 Ibs. per cu. ft. and
had about 46 per cent, of voids. The gravel stones weighed
about 111 Ibs. per cu. ft. and had about 40 per cent, of voids.

Instead of barrels for measuring the proportions of sand
and cement, gage boxes, without bottoms, were used. The
following sizes were found convenient.

. Sand Box , Stone Box v

Proportions Vol. Vol.

Size cu. ft. Size cu ft.

12^4 2'9"x2'xl'8" 9.25 5'x4'5^" 14.80

13 6 2'9"x2'x2'0" 11.10 5'x6'8 " 22.20

12 5 2'9"x2'xl'4" 7.40 5'x6'6^" 18.50

2'9"x2'xl'8" 9.25 5'x7'.2K" 24.05

All concrete except that on the sides was put in rather
wet and rammed till it quaked. On the sides of the reservoir
a drier mixture was necessary to prevent flowing down the
slope. Where possible a spade was used to puddle the con-
crete next to the forms and a fine smooth finish was given to
the work.

As to the possibility of a concrete wall being impervious to
water, attention is called to the partition wall in the gate
house between the water chamber and the gate chamber. This
wall is 23 ft. high, 11 ft. wide, and 3 ft. thick, and there is a
head of 19.5 ft. of water against it. In dry weather there is
no moisture on this wall, although no more care was taken
with it than with other portions of the work.

All the concrete, when laid, was kept continually wet for at
least a week, and after that occasionally sprinkled until it
was covered or the work was completed.

The ordinary concrete gang was made up of a sub-foreman,
2 men gauging materials, 2 men mixing mortar, 3 men turning
the concrete, 3 men wheeling concrete, 1 man placing, and 2
men ramming. All the concrete was mixed and placed by
hand. Two gangs were ordinarily employed, placing about
20 cu. yds. per day, each, or about 1.43 cu. yds. per day per

258 HANDBOOK FOR CEMENT USERS.

man. The concrete was turned at least three times before
placing.

Besides the gang on the concrete three plasterers and three
helpers were employed on the upper layer on the slopes.

After the banks were finished a granolithic walk, 6 ft. wide,
was constructed about the top of the bank. This walk has a
foundation stone about 12 ins. thick, on top of which is a
concrete layer 4 ins. thick at the sides and 5 ins. thick at the
middle). This concrete is surfaced with granolithic finish
about 1 in. thick. The walk was laid in separate blocks, about
6 ft. square, a steel templet being used to keep adjacent
blocks entirely separate. The average gang employed on the
concrete of the walk was six men and a single team, while two
masons and a tender did the finished surface. The average
amount of work finished per day was 60 lin. ft.

There are various rather unimportant variations from this
method. In regard to dimensions of blocks, in Pittsburg the
blocks were made 9 inches thick and 7 feet square, the joints
%-inch wide at bottom and %-inch at top and filled with
.asphalt. A half inch of Portland cement was put on as a top
coat. At Albany the blocks are 7 feet square and asphalt
joints are % inch wide and half the depth of the block.
Blocks are made in some cases as large as 20 feet square.

In regard to proportions of materials, Pittsburg used con-
crete in proportions of 1, 2, 4, of Portland cement, sand and
broken stone, the top coat being 1 to 1 mortar. Havana.
Cuba, used two 6-inch layers of proportions 1, 3, 5. Syracuse
used a 9-inch layer of 1, 2, 3, using natural cement. Special
treatment is sometimes necessary, using asphalt, clay or
other impervious materials in foundation or lining to prevent
leakage.

CEMENT WALKS.

Some general instructions and specifications for laying
cement walks are given, and they are followed by samples of
full specifications from St. Louis, Pittsburg and Indianapolis
as examples of the variations in specifications which produce
good walks.

It is especially important in this class of work to use the
best materials, carefully selected, and to exercise great care
in every part of the work.

Thorough drainage of tlie foundation course of gravel,
broken stone or cinder must be assured, and this foundation

SPECIFICATIONS FOR THE USE OF CEMENT. 259

must be at once firm and porous, and well compacted. It is
well to do the excavating and filling some time before the
concrete is put in, thus securing thorough setting. But cross
boards should be placed on the fill and plank laid lengthwise
on these to prevent packing of one portion more than another,
where the wall is much used.

The thickness of the porous bed is not important if it be
certain it is .sufficient to insure solidity and perfect drainage
at every part.

The bed should be well wet down before putting in the con-
crete.

Two by four inch strips should be firmly staked on edge
with upper edge to grade, and braced apart to desired width
with cross pieces between.

A thoroughly mixed body of concrete composed of one part
cement, two parts sand and four parts gravel, pebbles or
broken stone, is shoveled between the strips, having been
tempered to such degree of dampness that when rammed
solidly to place some water will be forced to the surface.

Sufficient concrete is used that about three-quarters inch
space remains uniformly between the surface of grade and
the surface of concrete. The concrete is then cut into blocks
with an ax or wedge-shaped tool which leaves a Y opening or
groove between the blocks. The blocks should not be larger
than 4x6 feet.

The position of the grooves should be carefully located on
the strips or otherwise.

Finally a coat of cement mortar of one part cement and one
and one-half parts sand (of excellent quality, coarse, sharp
and clean), so tempered that it can be worked to a surface
with a straight-edge shifted on the surface of the side strips,
is applied to the surface of the concrete. A thin film of mor-
tar is troweled on to the surface in advance of the main body,
being spread over by the straight-edge.

After the straight-edge, a float is used. This is applied just
as the surface film of water is being absorbed, and immedi-
ately after it a slight troweling to a smooth surface is ap-
plied. The troweler then cuts entirely through the walk in
the lines of the joints already formed, with his trowel and
bevels the edges of the cut or rounds them with an edging
tool. The outer edges are also rounded or beveled.

The walk is then covered with sawdust, fine sand or canvas
to protect it from the sun and air, and kept well wet for at
least 48 hours when it may be uncovered and allowed to dry
out slowly, with frequent w'ettiugs for several days. The
strips may then be removed.

260 HANDBOOK FOR CEMENT USERS.

Do not dust the surface or trowel very long.

Inside of yards or lawns less thickness of concrete and less
proportion of cement may be used.

The following, selected from specifications for cement walks
prepared by Albert Moyer, of New York City, gives the opin-
ions of a practical man upon some questions in sidewalk con-
struction concerning which there is much discussion.

In laying a cement sidewalk keep constantly in view the fact
that the form of construction is artificial stone slabs or (lags,
each slab subject to all the conditions surrounding artificial
stone, such as careful selection of materials, thorough mixing,
tamping, and seasoning, allowance in the joints for expansion,
upheaval by frost, and wear. Portland cement concrete ex-
pands and contracts with temperature changes in practically
the same ratio as steel. Upheaval by frost is obviated by pro-
viding an under drainage.

For drainage foundation excavate to a sufficient depth so as
to get below the frost line, fill in with clean cinders or broken
stone to within 4 inches of top of established grade of the pave-
ment. Tamp well and evenly and thoroughly wet the cinders
or stone.

For cement sidewalks in warm climates where freezing does
not occur excavate to a depth of 4 inches below established
grade of the sidewalk, tamp the ground well and evenly, omit
the cinder or broken stone drainage foundation.

Screenings or crusher dust if used for wearing surface must
be of crushed quartz, granite or other hard, tough stone, free
from mica or foreign matter and crushed so that the largest
piece will pass through a sieve of i4~i ucn meshes, the particles
graded in size from fine to coarse; the crusher dust to contain
not over 30 per cent, of fine dust. Sand does not make as good
a wearing surface as screenings or crusher dust.

Cinders or broken stone for foundation drainage must be
broken so that the largest piece will not exceed 3 inches, and the
smallest to be not less than 1 inch in diameter, free from dirt
or other foreign matter. The cinders to be carefully selected
furnace cinders. Blast furnace slag, broken as above, may also
be used.

Ketempering of cement mortar should never be permitted.

Do not allow any block to bear directly against any
solid body, such as stone curb, building, post, manhole-
rim, etc. Leave the same space (about % inch) between
pavement and such fixtures as is between the blocks them-
selves. This note applies to the base and top as designed
to avoid cracks and chipping due to expansion and

SPECIFICATIONS FOR THE USE OF CEMENT. 261

contraction from temperature changes. This space can be
conveniently provided for by the use of thick tar paper or felt.

Immediately cover the pavement with canvas, tar paper, or
boards, raised a few inches so as not to come in contact with
any part of the pavement.

After pavement has been down 15 to 20 hours, wet thoroughly
with a sprinkler. Keep pavement covered for a week and con-
stantly wet; do not let it dry for a moment at any time during
the first week.

Do not put any water on the pavement until it has set
hard, usually after 15 or 20 hours, then it becomes very neces-
sary to keep the pavement wet thoroughly and continuously for
as long a time as economy will permit. Artificial stone is best
when kept entirely under water for at least one month. It be-
comes stronger and harder the longer it is kept wet; the same
law applies to cement sidewalks as to artificial stone.

Do not use coloring matter unless absolutely necessary.
Nearly all coloring matter reduces the strength of the mortar.

Do not lay new concrete on old concrete.

Do not spread a top coat over an old concrete base.

Cut out roots of trees that may extend under sidewalk.

Do not use a base of one brand of cement and a top surface
of another; the different quality of the cement, difference in
time of setting or hardening, contraction, expansion, etc., often
causes top to crack from base.

GRANITOID SIDEWALKS, ST. LOUIS, MO.

The sidewalks shall be of three separate and distinct thick-
nesses and kinds, and shall be classified as follows: "Ordi-
nary Single Flagging, "Extra Double Thick Flagging" and
"Driveway or Entrance Flagging," and shall be laid in the
different localities within the prescribed limits at the discre-
tion of the Street Commissioner, who shall determine which
of the above named kinds shall be laid.

Grading. All grading which may be necessary to be done
in repairing or constructing sidewalks in consequence of the
adjustment of the grade of any pavement, or in order to pro-
tect the work, shall be made of such dimensions as shall be
ordered, and all the filling required shall be spread in thin
layers, and must be well rammed, so as to render it perfectly
compact. All surplus earth shall be hauled away, and all
borrowed earth, which may be required, shall be furnished by
the contractor.

Ordinary Single Flaggin g .After the grading and shaping
is done a foundation of cinders not less than eight (8) inches
thick shall be placed upon the sub-grade, which shall be well

262 HANDBOOK FOR CEMENT USERS.

consolidated by ramming to an even surface, and which shall
be moistened just before the concrete is placed thereon.

After the sub-foundation has been finished the artificial
stone flagging shall be laid in good, workmanlike manner.

The same to consist of two parts: 1st. A bottom ' course,
to be three and one-half (3%) inches in depth. 2d. A finish-
ing or wearing course, to be one-half (i/>) inch in depth.

The bottom course shall be composed of crushed granite
and the best Portland cement, equal to the Dyckerhoff brand,
and capable of withstanding a tensile stiength of 400 pounds
to the .square inch after having been three hours in the air
and seven days in water, and shall be mixed in the proportion
of one part cement to three parts of crushed granite.

The crushed granite shall consist of irregular, sharp-edged
pieces, so broken that each piece will pass through a three-
fourths (%) of an inch ring in all its diameters, and which
shall be entirely free from dust or dirt.

The crushed granite and the cement in the above-mentioned
proportions shall first be mixed dry, when sufficient clean
water shall be slowly added by sprinkling, while the material
is constantly and carefully stirred and worked up, and said
stirring and mixing shall be continued until the whole is thor-
oughly mixed.

This mass shall be spread upon the sub-foundation and
shall be rammed until all the interstices are thoroughly filled
with cement.

Particular care must be taken that the bottom course is
well rammed and consolidated along the outer edges.

After the bottom course is completed the finishing or
wearing course shall be added. This course to consist of a
stiff mortar composed of equal parts of Portland cement and
the sharp screenings of the crushed granite, free from loamy
or earthy substance, and to be laid to a depth of one-half (%)
of an inch and to be carefully smoothed to an even surface,
which, after the first setting takes place, must not be dis-
turbed by additional rubbing.

When the pavement is completed it must be covered for
three days and be kept moist by sprinkling.

Extra Double Thick Flagging. After the grading and
shaping is done a foundation of cinders not less than six (6)
inches thick shall be placed upon the sub-grade, which shall
be well consolidated by ramming to an even surface and
which shall be moistened just before the concrete is placed
thereon. After the sub-foundation has been finished the arti-
ficial stone flagging shall be laid in a good, workmanlike
manner.

SPECIFICATIONS FOR THE USE OF CEMENT. 263

The same to consist of two parts: 1st. A bottom course
to be five (5) inches in depth. 2d. A finishing or wearing
course to be one (1) inch in depth.

The bottom course shall be composed of crushed granite
and the best Portland cement, equal to the Dyckerhoff brand,
and capable of withstanding a tensile strength of 400 pounds
to the square inch after having been three hours in air and
seven days in water, and shall be mixed in the proportion
of one part of cement to three parts of crushed granite.

The crushed granite and the cement in the above-mentioned
proportions shall first be mixed dry, then sufficient clean
water shall be slowly added by sprinkling, while the material
is constantly and carefully stirred and worked up, and said
stirring and mixing shall be continued until the whole is
thoroughly mixed.

This mass shall be spread upon the sub-foundation and
shall be rammed until all the interstices are thoroughly filled
with cement.

Particular care must be taken that the bottom course is
well rammed and consolidated along the outer edges.

After the bottom course is completed the finishing or wear-
ing course shall be added. This course to consist of a stiff
mortar composed of equal parts of Portland cement and the
sharp screenings of the crushed granite, free from loamy or
earthy substances, and to be laid to a depth of one (1) inch
and to be carefully smoothed to an even surface, which, after
the first setting takes place, must not be disturbed by addi-
tional rubbing.

When the pavement is completed it must be covered for
three days and be kept moist by sprinkling.

Driveway or Entrance Flagging. After the grading and
shaping is done, a foundation of crushed limestone and hy-
draulic cement mortar shall be laid to a depth of six (6) inches
on the sub-grade. The stone used in this concrete shall be
broken so as to pass through- a two (2) inch ring in its largest
dimensions. The stone shall be cleaned from all dust and dirt
and thoroughly wetted and then mixed with mortar, the gen-
eral proportion being one part of cement, two parts of sand
and five parts of stone. It shall be laid quickly and then
rammed until the mortar flushes to the surface. No walking
or driving over it shall be permitted when it is setting, and
it shall be allowed to set for at least twelve hours, and such

264 HANDBOOK FOR CEMENT USERS.

additional length of time as may be directed by the Street
Commissioner or by his duly authorized agent before the
pavement is put down.

Pavement. After the sub-foundation has been finished the
artificial stone flagging shall be laid in a good, workmanlike
manner. The same to consist of two parts: 1st. A bottom
course to be five (5) inches in depth. 2d. A finishing or wear-
ing course to be one (1) inch in depth.

The bottom course shall be composed of crushed granite
and the best Portland cement, equal to the Dyckerhoff brand,
and capable of withstanding a tensile strain of 400 pounds to
the square inch after having been three hours in air and
seven days in water, and shall be mixed in the proportion of
one part cement to three parts of crushed granite.

This mass shall be spread upon the sub-foundation and
shall be rammed until all the interstices are thoroughly filled
with cement.

Particular care must be taken that the bottom course is
well rammed and consolidated along the outer edges.

When the pavement is completed it must be covered for
three days and be kept moist by sprinkling.

CEMENT SIDEWALKS,, PITTSBURG, PA.

Pavements of this class shall consist of a foundation of
coarse cinder, or broken stone, six (6) inches deep; a layer of
Portland cement concrete, three (3) inches thick, and a wear-
ing surface of Portland cement mortar, one (1) inch thick,
making the total thickness of the completed pavement at
least ten (10) inches.

SPECIFICATIONS FOR THE USE OF CEMENT. 265

The broken stone or cinder to be used in the foundation
shall be of approved quality, broken so that the largest di-
mension of any piece will not exceed three (3) inches, nor the
smallest dimension of any piece be less than one (1) inch, and
must be free from dust, dirt or other foreign matter.

Broken stone for concrete shall be a good, hard stone that
will not be affected by the weather^ broken so that the largest
dimension of any stone shall not exceed one and one-half (l 1 /^)
inches, nor the least dimension of any stone be less than one-
quarter (i/4) of an inch, and must be free from dust, dirt or
other foreign matter.

Gravel used for concrete shall be washed river gravel of
such sizes that the greatest diameter of any pebble will not
exceed one and one-half (l 1 /^) inches, nor the least dimension
of any pebble be less than one-quarter (%) of an inch, and
must be free from dust, dirt or other foreign matter.

The sand shall be of the best quality of coarse, sharp, clean
Allegheny river sand, free from dust, loam or other foreign
matter, or a sand equal in quality there to.

Portland cement shall be equal in every respect to that
hereinbefore specified under the heading "Specifications for
Cement." [See the chapter on "Specifications for Cement"
for the same.]

The screenings to be used in the wearing surface shall be
crushed quartz, granite, Ligonier stone or other stone equal
in quality thereto, crushed so that the largest piece will pass
through a sieve of one-quarter-inch meshes.

Water shall be fresh and free from earth, dirt or sewage.

The width of the pavement shall be such as the director
may specify.

The foundation shall be of cinder or broken stone as here-
inbefore specified, and shall be drained to the curb ditch by
10-inch by 12-inch stone drains placed every 25 feet along the
line of the walk.

The concrete shall consist of 1 part in volume of Portland
cement, 3 parts of sand and 6 parts of broken stone or gravel.

The cement or sand in the specified proportions shall be
thoroughly mixed dry on a tight platform with shovels or
hoes until no streaks of cement are visible.

Water shall be added to the sand and cement, mixed in
accordance with the foregoing directions, in sufficient quanti-
ties to produce a mortar of the desired consistency, and the
whole thoroughly mixed with shovels or hoes until a homo-
geneous mass is produced.

The mortar, prepared as hereinbefore specified, shall be
spread upon the platform, the proper quantity of broken

266 HANDBOOK FOR CEMENT USERS.

stone 1 or gravel, after having been thoroughly wetted, shall
then be spread over the mortar and the mass thoroughly
turned over with shovels or hoes not less than three (3)
times, or until every pebble or piece of broken stone is com-
pletely coated with mortar.

Water shall be added by sprinkling during the process of
mixing if required to secure a better consistency.

All surfaces on or against which concrete is to be laid
shall be thoroughly cleaned and dampened by sprinkling with
water just previous to placing the concrete.

The concrete shall be evenly spread upon the foundation,
as soon as mixed, in a layer of such depth that after having
been thoroughly compacted with rammers of approved pat-
tern it shall not be in any place less than three (3) inches
thick, and the upper surface of it shall be parallel with the
proposed surface for the completed pavement.

The slab or flag divisions shall be formed by cutting the
concrete clear through, on the required lines, as soon as laid.
The space made by the cutting tool shall be immediately filled
with dry sand and well rammed.

Concrete should not be mixed in larger quantities than is re-
quired for immediate use, and no batch shall be larger than
can be made of one barrel of cement with the proper propor-
tions of sand and stone.

Concrete shall not be dropped from too great a height or
throAvn from too great a distance when being placed upon
the work.

The wearing surface shall be composed of one part in vol-
ume of Portland cement and two (2) parts of screenings of
the quality hereinbefore specified.

The cement and screenings in the specified proportions
shall be thoroughly mixed dry, on a tight platform, witli
shovels or hoes, until no streaks of cement are visible.

Water Tshall be added to the screenings and cement, mixed
in accordance with the foregoing directions, in sufficient
quantities to produce a mortar of the desired consistency,
and the whole thoroughly mixed with shovels or hoes until a
homogenous mass is produced.

The mortar while fresh, shall be spread upon the concrete
base before the latter has reached its first set, in such quan-
tities that after being thoroughly manipulated and spread
over the concrete it will make a layer one inch thick, con-
forming to the required grade and cross-section.

A coating of equal parts of Portland cement and dry, fine
sand or screenings thoroughly mixed, shall be swept over the
surface and the surface dressed and smoothed. On steep

SPECIFICATIONS FOR THE USE OF CEMENT. 267

grades the top dressing shall consist of coarse granite or
Ligonier stone screenings and cement.

The surface shall then be cut into flags, the markings to be
made directly over the joints in the concrete and cut clear
through the wearing surface.

The flags shall then be trued up and marked all over, with
the exception of a border of about an inch in width along the
edges, with a toothed roller.

The pavement shall be kept moist and protected from the
elements and travel until it has set.

Entrances from adjoining streets or walks to all private
or public premises shall be preserved by the contractor.

The completed pavement shall, unless otherwise ordered,
have a rise of one-quarter (*4) of an inch to the foot rising
from the curb.

Board or timber forms shall be provided by the contractor
to mold the concrete and mortar to the required shape, and
shall be left in place until the concrete or mortar is set.

Retempering of concrete or mortar will not be permitted,
and mortar or concrete that has begun to set before ram-
ming is completed shall be removed from the work.

Concrete or mortar that fails to show a proper bond or
fails to set after, in the opinion of the director, it has been
allowed sufficient time, shall be taken up and replaced with
new concrete or mortar, of the proper quality, by the con-
tractor.

If at any time during the guarantee period any cracks,
scales or other defects develop in the pavement, the pave-
ment at that point shall be taken up and relaid with new ma-
terials, in accordance with these specifications, by the con-
tractor.

CEMENT SIDEWALKS, INDIANAPOLIS, IND.

1. Stakes will be set by the engineer to define the line of
one edge of the walk, and the grade marks will indicate the
top of the walk at said time. The transverse slope of the
walk will be one-fourth inch per foot, and will be determined
with level and grade board made according to drawing in
engineer's office.

2. The sidewalk shall be graded to the width as shown on
plan for the entire length of the improvement, including all
wings and crossings, as shown on plan, and sixteen inches
below the finished surface of the walk. The grading must be
smoothly and neatly done, all large stones, bowlders, roots,
sods and rubbish of every description being removed from the
grade, and the entire work must be made to conform fully
to the profile and the grade of the walk when finished.

268 HANDBOOK FOR CEMENT USERS.

Soft, spongy or loamy spots in the sub-grade must be taken
out and refilled with good material and the grade solidified
by ramming.

3. Trees shall not be injured, cut down or otherwise dis-
turbed except by order of the engineer. Roots of trees
which are not removed, but which are contiguous to the line
and grade of the walk or in any way interfere therewith,
must be trimmed and cut away as the engineer shall direct,
and where the engineer directs the stones shall be fitted to
the trees and roots covered with earthenware half-pipes.
Any tree removed must be grubbed for the entire width of
the sidewalk and also its roots that rise above the level
of the sub-grade. No extra compensation for such work will
be allowed.

4. Upon the sub-grade thus prepared and after inspection
and acceptance of the same, a foundation of clean creek or pit
sand and fine gravel, or broken stone, in such proportions as,
when rammed, will form a solid and compact mass, shall be
spread to a uniform depth of twelve inches, all to be rammed
and tamped until it presents a hard, smooth surface. It shall
be sprinkled with water as required, enough remaining to ren-
der the surface as moist as the concrete at the time the latter
is laid.

5. Wooden frames four inches in height will be placed in
the manner necessary to outline both external edges of the
walk accurately, the top of the frames being located to coin-
cide with the established grade of the walk. Gauges must be
used to render surface of foundation layer and of concrete
parallel to the top of the walk. Concrete will be made as
follows: One measure of Portland cement of the kind else-
where specified for sidewalks, and two measures of clean, sharp
sand shall be mixed thoroughly, while dry, and then made into
mortar with the proper amount of water as determined by the
engineer; broken stone or gravel not over one inch in any di-
mension, thoroughly cleansed from dirt and dust and drenched
with water, but containing no loose water in the heap, will then
be mixed immediately with the mortar in such quantities as
will give a surplus of mortar when rammed. This proportion,
when ascertained, will be regulated by measure. The engineer
may accept a clean, natural mixture of sand and gravel if it
is uniform and contains no dirt or other foreign matter, or
stones larger than above specified. The proportions will be
one part of cement to five parts of the mixture, to be mixed
dry, the water being added afterward. Each batch of concrete
will be thoroughly mixed, and the engineer may prescribe the
number of times it shall be turned over, wet and dry, to accom-

SPECIFICATIONS FOR THE USE OF CEMENT. 269

plish this result. In general it shall be turned (or cut) four
(4) times dry and three (3) times wet. It will then be spread
to fill the frames even full and be at once compacted thor-
oughly by ramming until free mortar appears on the surface
and until a one and one-fourth (l 1 /^) inch gauge, furnished by
the inspector, will pass over the concrete. It is the inten-
tion that the surface of the concrete, when thoroughly
rammed, shall be at least one and one-fourth (l 1 /^) inch below
the top of the frame. The whole operation of mixing and
laying each batch of concrete will be performed as expedi-
tiously as possible.

6. After each batch of concrete is laid, as required, it
shall be immediately covered with the wearing surface. Any
portion of the foundation which has been left long enough to
have any appearance of setting shall be taken up and relaid
before the top is put on, and under no circumstances will
concrete be allowed to remain over night before top is put
on. The wearing surface or top shall be composed of five parts
of the same kind of cement used in the concrete and seven parts
of clean, sharp sand, thoroughly mixed dry and made into mor-
tar with the proper amount of water as determined by the engi-
neer. It shall be evenly and compactly spread to the finished
surface of the walk and made smooth and even by troweling
and floating. The top and concrete foundation shall be cut into
blocks of dimensions approved by the engineer, forming an ex-
pansion joint between adjoining blocks. The pavement shall be
properly fitted around all fixtures in the sidewalks, the edges of
the pavement to be beveled from top surface to bottom of con-
crete with the material used on the top.

7. Coloring matter of quality and quantity approved by the
engineer will be required for the top surface. On business
streets the engineer may require the surface to be carefully
rolled with a toothed roller when the finish is completed.

8. Where walks of any description that now exist on the
street shall be accepted by the Board of Public Works or the
engineer they shall be relaid if the engineer deems it neces-
sary, to the grade and line established, and if the price there-
for is not fixed in the contract, it shall be determined by
adding 15 per cent, to the actual cost of the work as deter-
mined by the engineer. Similar procedure will be taken for
extra work in resetting area ways and similar structures to
grade and line. When a driveway occurs in the line of the
walk the walk will be increased in thickness and laid accord-
ing to plans furnished by the engineer, the additional expense
to be paid by the owner.

9. All blocks used shall be perfect and of good quality in

270 HANDBOOK FOR CEMENT USERS.

all respects, free from cracks, warps and similar imperfec-
tions. Special care shall be taken to protect the walk at
night. If found not to comply with the specifications in any
respect at any time up to the end of the guarantee period they
shall be taken out immediately and replaced by the contractor
at his own expense.

10. A list of Portland cements which have been tested in
the laboratory and found satisfactory for use in the construc-
tion of cement walks will be found in the office of the city
engineer.

11. Embankments shall be formed of compact earth free
from large stones or perishable materials and shall be raised
to such a height as to conform to the grade and line after
such embankment shall have become well settled by properly
tamping, ramming or rolling the same.

12. The lawns shall be graded to conform to walk and curb
grades and dressed with fine earth, raked and left smooth. If
sodding is specified the lawns shall be sodded with blue grass
sod, free from weeds and such as to meet the approval of the
city engineer. All joints will be broken in laying and the sod
shall be laid to a uniform and even surface. The sodding
must be kept sprinkled until such time as the entire improve-
ment is accepted by the city. If the lawns are already in grass
they shall be left in proper condition satisfactory to the city
engineer and any unnecessary damage shall be repaired. Traf-
fic on the street must not be interfered with any more than is
necessary, and the walk must be laid in sections which will
interfere as little possible with pedestrians. As soon as the
walk has been completed in front of any lot, the contractor
shall clean the street in front of completed sidewalk of all
surplus material, cement, sand, gravel, barrels, etc., used
in its construction, and permanently improved streets shall
be kept clean in front of completed sidewalk until accepted by
the city.

TYPICAL SIDEWALK SPECIFICATIONS.

The following notes on typical specifications for concrete
sidewalks, by Sanford E. Thompson, Asso. M. Am. Soc. C. E.,
in Cement, are of interest and value in this connection :

The specifications for the construction of concrete side-
walks in various localities throughout the United States
show considerable uniformity, and yet vary sufficiently so
that an outline of methods employed in different places may
be of interest.

It is not intended to draw from these fragmentary notes
a set of ideal specifications, for the difference in construction

SPECIFICATIONS FOR THE USE OF CEMENT.

271

followed in different cities may be due partly to the character
of the soil upon which the walk is to be laid, partly to the
climate that is, to the extent to which the sidewalk may be
affected by frost, and in part to the kinds of material which
can be most readily obtained. The amount of wear which the
pavement is to receive may also influence the thickness or the
construction. It is believed that the data given, however, will
furnish hints of value to those interested in this line of work.

In the cities selected to -illustrate the different methods of
paving throughout the country scarcely two of them desig-
nate concrete sidewalks in their specifications by the same
terms. They are variously called "Artificial Stone Side-
walks," "Portland Cement Flag Stonewalks," "Granolithic
Cement Concrete," "Cement Sidewalks," "Portland Cement
Concrete Sidewalks," "Artificial Stone Flagging," or simply
"Artificial Walks."

The styles of construction in the several cities vary less
than the names by which the sidewalks are designated. The
following table gives a meagre outline of the dimensions
and the character of the materials employed in several cities
selected in different parts of the United States :

City.

Foundation.

Base

Wearing

Surface.

Dry
Coat.

Size of
Blocks.

Yrs
10
3

Thick-
ness

Material

Thick-
ness

Pro-
por-
tions.

Thickne's

Pro-
por.

Pro.
Por.

1 1

Boston

Rochester,
N. Y
Philadelphia,
Pa

Washington,
D. C
Chicago. Ill-
Milwaukee,
Wis

St. Louis, Mo.
Omaha, Neb

12"
6"
3"

Oorl2"*

8"
4"

Broken stone, gravel
or cinders,
Sand, gravel, broken
stone or cinders
Sand, gravel, broken
brick, stone or cin-
ders

Cinders
Cinders or broken
stone

Cinders

4V4" av.
2V 2 "

3V4"
3"

1:2:5
1:5

1:2:5
1:2:5
1:3:5

1:3
1:2:4

1"
1"

%"
1"

Vz"
1"

1:1
2:3

1:2

2:3

1:1

1:1
1:2

1:1
1:1

Bet. 3V 2 -6
ft. sq.

5ft.X6ft.

Bet. 24-36
ft. sq.

5
10

1
5

Gravel, slag or stone,

3:1

* 12" cinders required where the soil is not clean sand.
** Specified for each contract.

This table merely illustrates some of the differences in con-
struction. To show more clearly some of the special methods
followed, the various divisions of the work will be considered
more in detail, using for the sake of uniformity the same cities
classified in the table.

Foundation. In all of the cities the specifications require
that excavation, or fill, shall be made to a definite sub-grade,
and that all insecure or spongy material below this sub-

272 % HANDBOOK FOR CEMENT USERS.

grade shall be dug out and refilled with gravel or its equiva-
lent and thoroughly puddled, rammed or rolled. Foundation
to be placed upon this sub-grade varies considerably in dif-
ferent localities, both in the character of the material and
the thickness of the layer. The character of the sub-soil and
the climate influence the thickness necessary for good work.
Many places require that the material used shall pass
through a iy 2 or 2-inch ring. All cities require that it shall
be thoroughly rammed, and sometimes puddling is specified.

Concrete Materials. Portland cement is always required,
and in general the selection of the brand is limited to the best
German or American cements. Some cities specify only Ger-
man Portland; others give a list of German and American
Portlands from which selection may be made; while others
give representative brands and allow some discretion to the
superintendent.

The specifications for the cement in most of the cities re-
quire that when sifted through a sieve of 10,000 meshes per
square inch there shall not be left over 10 per cent, residue.
St. Louis allows 15 per cent, residue, and Chicago allows only
8 per cent. In addition to this test, Boston and Cambridge,
Mass., require that when sifted through a sieve of 32,500
meshes per square inch, there shall not be left over 45 per
cent, residue. Chicago requires that, when mixed with 20 per
cent, of water by measure, the initial set shall not take place
in less than 45 minutes. Chicago also requires that the cement
shall meet the requirements of the "boiling" test.

For tensile strength part of the cities require 50 pounds
per square inch for neat briquettes which have remained
twenty-four hours in air and six days in water, while others
require 40 pounds, with the same test. Some of the cities re-
quire an additional test of cement mixed with sand or
screenings. In Chicago one part of cement and four parts
fine granite screenings, exposed one day in air and six days
in water, must show a tensile strength of 200 pounds per
square inch and a gradual increase of strength of 15 per cent,
at the end of twenty-eight days. In the District of Columbia
the specifications for the cement must conform to the cur-
rent specifications for the Engineering Department of the
District of Columbia.

The sand for use in the base is generally a clean, sharp
sand. In Chicago clean torpedo sand is specified, ranging
from y$ inch size down to the finest. Voids there are not
to exceed 30 per cent., and the weight must not be less than
190 pounds per cubic foot. Washington requires that sand
shall range from fine to coarse, and shall be free from im-

SPECIFICATIONS FOR THE USE OF CEMENT. 273

purities, but may show when shaken with water and after
subsidence not more than 3 per cent, by volume of silt or loam.

The kind of material used for the coarse stuff of the con-
crete base varies considerably in different places. Boston re-
quires that it shall consist of sharp gravel or broken stone,
not exceeding % inch in size. Rochester, N. Y., specifies that
fine, clean gravel, not over % inch in size, shall be delivered
on to the work and sifted through an inclined screen having
16 meshes per square inch. For the base of the pavement is
taken the clean, medium, fine gravel from the front of the
screen, and for the wearing surface is used the sand behind
the screen. In Philadelphia the stone must be solid trap
rock, or other approved hard slag or stone, and must pass
through a li^-inch ring. Chicago specifies crushed limestone
not more than 1 inch in any direction. Milwaukee states that
there shall be used cubical broken limestone not over % inch
in any direction. Omaha allows broken stone or slag up to
~L~y 2 inch in greatest diameter.

The material for the wearing surface also varies largely
in different localities. Boston requires one part of fine
crushed trap or granite rock, screened through i/4-inch mesh,
or one part of Newburyport sea sand to one part of Portland
cement. In Philadelphia two parts of crushed granite to one
part imported Portland cement 'are used, and the granite
must be free from dust and of such size that the largest par-
ticles shall pass through a i/o-inch sieve. In Washington the
same sand is used for the surface coat as is used for making
the concrete of the base. Chicago uses one part Portland
cement to one part torpedo gravel. Milwaukee requires one
part Portland cement to one part finely crushed granite, which
shall have square or cubical fracture and not measure
over 14 i nc 'h i anv direction. Omaha requires substantial
stone or granite which will pass through i/^-inch mesh screen,
mixed one part cement to two of crushed stone.

A few other cities require that dry cement shall be floated
on top of the surface when finishing. In Philadelphia this
dryer is to be one part cement to one part sharp flint sand.
In Omaha, Neb., three parts Portland cement to one part
sand.

Concrete Curl}. In Boston the foundation for a curb is
12 inches thick and consists of broken stone, screened gravel
or soft coal cinders thoroughly rammed. Upon this founda-
tion is laid concrete 12 inches wide and 8 inches deep, and
before this is dry a layer of concrete 7 inches wide at the
bottom and 11 inches deep is placed, tapering on the outside
to 6 inches wide at the top. The inside face is vertical. On

274 HANDBOOK FOR CEMENT USERS.

the face and top a 1-inch wearing surface is laid. The ex-
posed face is brushed with a little brush before becoming en-
tirely dry.

Combined Curl} and Gutter. In Milwaukee a combined
curb and gutter is often laid. This consists of a curb 5 inches
wide at the top, having 7 inches of face above the gutter and
a gutter 15 inches in width. It is constructed in alternate
sections of stone 6 feet in length. The face corner of the curb
is rounded to a radius of 1% inches. The gutter flag is
laid to a pitch corresponding to the 'crown of the street. Ex-
cavation is made to a depth of 11 inches below the gutter
flag, except where a sub-soil drain is required, when a 3-inch
drain tile is placed below this sub-grade. The foundation con-
sists of cinders or broken stone 6 inches thick,, and upon this
is laid the concrete core of the combined gutter and curb,
which is 4 inches thick on the bed and 4 inches in width in
the molds set for the curb. A 1-inch finishing layer is placed
upon the surface of the gutter and the face of the curb be-
fore it is dry, troweled as usual, and then finished with a
broom.

Driveways. Driveways are sometimes made of the same
thickness as the regular sidewalk and sometimes thicker. In
Rochester, N. Y., the total thickness for driveways is 6 inches,
4% inches of this being ' base and l 1 /^ inches the top.
In this city the contract price for a driveway is 1% times the
contract price for the walk. Surfaces of driveways are usually
marked off in 6-inch squares.

Clauses. Several of the cities have special clauses which
are of interest. Some of these apply particularly to the
locality of the city, while others might generally be adopted
to advantage.

In Boston the specifications require that no work shall be
done after November 15th, or in freezing weather. In this
city a metal plate bearing the name and address of the con-
tractor and the date of the year in which the sidewalk is laid
must be placed in each sidewalk. Boston requires that no
adjoining blocks shall be laid within six hours of each other,
and the requirement is also made that, where spalling, split-
ting off or other defects occur after completion, the entire
block or division must be replaced with a new block or divi-
sion, no patching being allowed.

Philadelphia specifies that no concrete shall be kept over
half an hour after mixing before it is laid.

Washington specifications state that only one barrel of
cement shall be used to a batch. In Washington, after level-
ing off the surface of the finishing coat or wearing surface, it

SPECIFICATIONS FOR THE USE OF CEMENT. 275

is beaten with wooden battens to break any air cells and
make surfacing perfectly solid. In long walks transverse ex-
pansion pieces of dressed white pine 1 inch by 6 inches are
provided at intervals of about 200 feet.

St. Louis requires that the bottom course, which is 3 l / 2
inches thick and is composed of one part Portland cement to
three parts of crushed granite, shall receive no less than one
barrel cement to each 30 square feet of sidewalk.

In most of the cities a uniform thickness of walk is re-
quired, but in Chicago the thickness is 5% inches in the cen-
ter, sloping to 4!/9 inches at each edge. Chicago requires
that the walks shall remain at the original grade for ten
years, and thus makes its contractors responsible for the
foundation. Many cities build their walks with a slope of
about % inch to the foot toward the gutter. A few specifica-
tions require that the walk shall be covered with moist sand
until the cement is set; some specify that the length of time
shall be three days. In some cases it is specified that the walks
shall, or may, when required, be rolled with a metal roller to
give an indented finish. In one or two of the cities the authori-
ties keep back 10 per cent, of the contract price to have a guar-
antee that repairs will be satisfactorily made. In the District
of Columbia this amount may be invested in Government bonds
if desired by the contractor.

Cement sidewalks may be laid over area ways by placing steel
beams of sizes suitable for the span and weight, and ordinarily
about three feet apart and laying the walk, arched on its under
surface, in the usual manner, wooden centers being used to hold
the concrete in place until it has set. Ordinarily the thickness
at the crown of the arch will be about four inches, and at the
supports sufficient to rest on the bottom flanges of the beams,
the finishing coat being carried over the tops of the beams so
as to form a uniform level surface. In some circumstances tie
rods to prevent spreading of the beams from the thrust of the
arches will be necessary.

It is a common practice in England to make slabs for con-
crete walks, using, for example, 1 part Portland cement to 3
parts crushed granite passing a 3-16-inch sieve, mixed thor-
oughly, dry, and with the smallest possible amount of water.
The molds are preferably metal lined, true in shape, with well
defined arrises, oiled to prevent sticking. By one process the
concrete is deposited by small shovelfuls in the mold while it
is rapidly shaken up and down in a machine. As the material

276 HANDBOOK FOR CEMENT USERS.

is shaken and troweled into place the moisture rises to the sur-
face, which is finished smooth and even. Six minutes' time is
taken in making the slab, which then sets for two days in the
mold and seven to nine days in the air, when it is immersed
for from seven to nine days more in a bath of "soluble silica"
made from flint and caustic soda. Hydraulic pressure is also
used in pressing the concrete into the molds, in which case
twenty-five slabs can be turned out in an hour.

CEMENT CURBING, INDIANAPOLIS.

The specifications for cement curb and gutter in Indianapo-
lis, under which over fifty miles have been laid, are as follows :

1. The curb stone must be of the best quality of granite, blue
oolitic limestone, stratified limestone or Berea sandstone, Park-
hurst or other artificial combined curb and gutter.

2. The contractor must make good any disturbance of side-
walk or lawn and any unnecessary disturbance of trees in set-
ting curb. Special construction to protect trees shall be made
when deemed necessary by the engineer.

3. The curb shall be under the same guarantee as the street
surface.

4. Combined curb and gutter shall be set to stakes set by
the engineer at points necessary to accurately designate the line
and grade of the proposed curb and gutter and any variation
in the height of the same between grade points and catch-
basin inlets.

5. The material to be used shall be Portland cement as speci-
fied in "Class A" for sidewalks (see Cement Sidewalk Speci-
fications), clean, sharp, coarse sand, crushed granite and gran-
-ite screenings with no stone with any dimensions over one inch.

6. The combined curb and gutter, whether Parkhurst or oth-
erwise, shall be constructed upon a two-and-a-half-inch con-
crete foundation before the concrete has become firmly set, so
as to secure complete adherence between the two. The com-
bined curb and gutter shall consist of a curb six (6) inches
wide at the top and generally seven (7) inches high above the
gutter where it joins the curb, and a gutter sixteen (16) inches
wide and six (6) inches deep so constructed that the curb and
gutter shall be monolithic. It will be composed of a concrete
core or backing faced with one inch in thickness of facing or
finishing mortar as shown by drawing on file in the office of the
City Engineer. The core or backing will be constructed of con-
crete composed of :

SPECIFICATIONS FOR THE USE OF CEMENT. 277

Portland cement 1 part

Clean sharp sand 2% parts

Crushed granite, crushed bowlders, or screened

gravel 5 parts

The crushed granite or bowlders shall be clean and sound,
broken so that every fragment will pass through a screen with
meshes one square inch, and all dust and particles smaller
than a grain of corn shall be screened out. The Portland
cement and sand shall be first well mixed dry and then sufficient
water added and the mixing continued until mortar of uni-
form composition and of the proper consistency is produced.

The crushed stone shall be added and thoroughly mixed with
the mortar until every fragment of stone is coated with mortar.
The concrete will then be put in place and well compacted by
ramming. The whole operation must be completed before the
mortar begins to set.

The facing or finishing mortar shall be composed of

Portland cement 2 parts

Clean sharp sand 1 part

Crushed granite , 3 parts

The crushed granite screenings shall be made from hard, sound
stone, and the fragments shall be of such size that all will
pass through a screen having one-fourth inch meshes, and all
fine dust shall be screened out. The facing mortar shall be
mixed in the same manner as the concrete described above.

If ordinary artificial combined curb and gutter is used it
shall be constructed as specified, and there shall be no projec-
tions on back and bottom, nor shall there be any other infringe-
ment on the Parkhurst patent. If Parkhurst curb is used a pro-
jection of one inch on back and bottom according to Parkhurst
patent shall be constructed as approved by the City Engineer.

7. Concrete, immediately after being mixed as above speci-
fied, shall be placed in the necessary forms or molds as rapidly
as it can be thoroughly compacted by ramming with a twenty-
pound rammer until the molds are full and the curb is ready
for surfacing.

8. The entire exposed surface of the curb and gutter shall
be faced by floating and troweling a coat of neat cement so as
to give it a uniform color throughout.

9. The work shall be carried on uniformly and the whole curb
and gutter completed while in a soft and plastic state, so that
it will become a homogeneous solid when set.

10. Sections in the curb shall not be less than seven feet long.

PARKHURST COMBINED CURB AND GUTTER.

First. The gutter and curb must be so combined as to form
one continuous and solid stone, and the combined curb and gut-

278 HANDBOOK FOR CEMENT USERS.

ter stone must be of the same general dimensions shown in
diagram on file.

Second. No additional allowance will be made for round
corners, nor for cutting holes for catch basins, and the price
paid for curbing shall be per linear foot in place complete.

Third. The materials to be used shall be Portland cement
and clean, sharp, coarse sand, medium-sized gravel or stone
crushed to the proper size, all subject to the approval of the
City Engineer.

Fourth. One part Portland cement, 2% parts sand and 5
parts gravel or crushed stone, shall be used in the backs and
bottom part of the curb. The exposed surface of both curb
and gutter shall be faced two (2) parts Portland cement and
three (3) parts fine crushed granite or trap rock, and sand
sufficient to make a smooth and even finish, but not to exceed
one (1) part.

Fifth. Portland cement must be used which shall stand a
tensile strength of 300 pounds per square inch after seven days,
six days in water and one day in air, and which shall have a
crushing strength of 2,000 pounds per square inch after hav-
ing been immersed in water seven days, and then exposed to
the air thirteen days, and the contractor shall furnish for
testing a sample of each and every barrel of cement to be used
in the construction of artificial stone curb and gutter when-
ever the engineer may request it.

Sixth. The material of the quantity and in the proportions
herein specified shall be mixed dry, and until the mixture
has an even color. Water shall then be added slowly while
the materials are being constantly and thoroughly mixed, and
stirred until an evenly tempered and complete mortar suitable
for molding is obtained. The mortar thus obtained shall be
immediately placed in the molds as rapidly (but not more
rapidly) as it can be thoroughly rammed until the mold is
full and the top is finished in the manner herein specified.

Seventh. The entire exposed face of the curb and gutter shall
be faced by floating and troweling, so as to give it a uniform
color throughout.

Eighth. The curbing is to be set to the true line and grade
of the street, on a bed of six inches of fine gravel, sand or broken
stone, or cinders thoroughly tamped. At the street and alley
corners the curb to be made on a curve of such radius as the
engineer may direct, with true and even joints, and to be of the
same description and set in the same manner as the curb before
described.

STREET CROSSINGS AND DRIVE PAVEMENTS.

Excavate street 6 inches below grade line if sub-stratum is

SPECIFICATIONS FOR THE USE OF CEMENT. 279

gravel, sand or porous soil; if clay or an impervious soil, ex-
cavate 4 inches more and fill that with cinders, gravel or
broken stone. Thoroughly roll to proper section, lay sub-drains
of 3-inch tile inside each curb line. Pavement is laid in two
courses: 1st layer, 4 inches thick, consists of 1 part Portland
cement and 4 parts clean gravel or broken stone and sand.
Proportion of gravel to sand, 2 to 1. Materials are thoroughly
mixed by machine ; just enough water being added so that when
well rammed water will show at surface.

Second layer, or top, 2 inches thick, which takes the wear,
consists of equal parts Portland cement and clean, sharp sand
or crushed granite, including all grains to the size of a pea.
Only the best of cement should be used for this purpose. The
top layer is thoroughly rammed. Both bottom and top layers
are divided during construction into rectangular blocks about
5 feet square, with edges neatly finished. The joints of blocks
coming directly over pipes are made like the keystone of an
arch, so they can be lifted up without disturbing neighboring
blocks, when repairs to pipes are necessary. To secure a posi-
tive foothold for horses, the surface can have v-shaped grooves
1 inch wide and 3-16 inch deep, 4 inches apart and running
at right angles with the street. Surface should be finished with
an ordinary plasterer's wooden float. Curbs are part of outer
blocks and consist of 1 part cement to 3 parts fine gravel. Ma-
terials for one square yard equal 144 pounds cement and 3
cubic feet of gravel.

CEMENT ROADWAYS IN RICHMOND, IND.

The portion of the specifications for concrete street pave-
ments in Richmond, Ind., H. L. Weber, City Engineer, which
refers directly to the construction of the roadway, is as fol-
lows:

The sub-grade will be thoroughly rolled, leveled and re-rolled
until it is true to grade and cross-section of the finished road-
way, and from 8 to 12 inches below the surface of the street, as
the case may be.

If found necessary for sub-drainage, upon the sub-grade place
3 or 4 inches of gravel, thoroughly wet and consolidated by
rolling or ramming, or both.

Upon this gravel foundation will be placed a layer of con-
crete 4 to 5 inches in thickness and finished to a true crown and
grade, parallel to the finished, street surface and 3 to 4 inches
below the same. This will constitute the foundation for the
cement roadway.

When sufficiently strong to sustain the roadway, the surface
of the concrete foundation will be covered with a coating of

280

HANDBOOK FOR CEMENT USERS.

fine sand, raked off with a flat board rake, by hand, so as to
remove all sand except that which may remain in low places
and voids in the concrete foundation.

vr -*
Upon this will be placed a layer of thin tar-paper (or other

SPECIFICATIONS FOR THE USE OF CEMENT. 281

suitable paper) or material to act as a separating joint.

Upon this will be laid the concrete pavement 2 to 3 inches
thick, in sections the full width of the street and - - feet in
length, with expansion joint next the gutters and ends.

This roadway will be composed of 1 part cement, 2 parts
sand, 3 parts gravel and 3 parts crushed stone, mixed with
water to form a rather wet mixture.

Upon this will be placed the wearing surface, one inch thick,
composed of 1 part cement, 1 part clean, sharp sand, and 1
part clean stone or granite screenings, mixed with water to
form a rather wet facing mixture.

The wearing surface will be deposited in two layers, one-half
inch thick, the first to be thoroughly rammed to insure perfect
contact; the second applied immediately after, and thoroughly
troweled and worked over, and made to conform to the finished
surface of the street by the use of the proper forms.

When sufficiently hard, the surface to be floated and steel
troweled, and, lastly, raised with a cork float, and when finished
must be true to grade and cross-section.

All concrete must be machine made, or thoroughly mixed by
hand, as the Engineer may direct.

CONCRETE STREET PAVEMENTS IN TORONTO, ONT.

The concrete street pavement in the street railway tracks on
King street, Toronto, Ont., was laid in 1899 in the following
manner :

The concrete was composed of 1 part of cement, % P ar t of
sand and 2 parts of crushed granite. The cost was from 65 to
75 cents per square yard and the work was carried out by the
City Engineer's Department. Next to each rail was placed a
row of paving blocks laid as stretchers. Owing to the very
large amount of traffic, this pavement has not proved entirely
successful and had to be repaired in 1902. The pavement
cracked near the rails and the constant traffic broke up the
surface. This disintegration was probably due, to some extent,
to the settlement of the rails. A similar pavement on a resi-
dential street has given good satisfaction.

Francis street, which is a short thoroughfare subjected to a
great deal of trucking, was paved with concrete in 1903, the
foundation being composed of 1 part of Portland cement, 3
parts of sand and 7 parts of broken stone, which is a similar
foundation to that used for asphalt or brick pavements. Be-
fore the foundation had time to set, a 2%-inch surface of what
is called granolithic concrete was put on. This forms the wear-
ing surface and consists of 1 part of cement, 1 part of sand and
3 parts of crushed granite, and is marked off in blocks 5 inches

282

HANDBOOK FOR CEMENT USERS.

by 12 inches, which gives it somewhat the appearance of a
scoria block pavement. Concrete walks, with curb, were laid
on this street previous to the concrete pavement, and expan-
sion joints were therefore provided throughout the entire width
of the pavement by leaving an opening one inch along each

3 TREE T

SECTIONS OF CONCRETE ROADWAYS, TORONTO, ONT.

curb, paving pitch being run into it until the opening was com-
pletely filled. Longitudinal expansion joints were also pro-
vided by leaving an opening three-quarters of an inch wide
through the pavement, the space being filled with pitch. It
would have been better to have made the longitudinal expansion
joints only one-half inch wide, as it is noticed that heavy
traffic has a slight tendency to' break away the concrete pave-
ment at these points. With this exception, the pavement is
in very good condition, no cracks being visible. The cost of this
pavement was $1.74 per square yard, the work being carried out
by the City Engineer's Department.

A similar pavement was laid in 1904 upon McFarren's lane,
but it was dished to the Center. This street is not subjected to
as heavy traffic as Francis street. It cost $1.92 per square
yard, the work being done by the City Engineer's Department.

PREPARATION OP CONCRETE FLOORS.

For concrete floors the proportions may be as follows :

SPECIFICATIONS FOR THE USE OF CEMENT. 283

. One part Portland cement, 3 parts of clean, sharp sand and
5 parts of stone, broken small enough to pass through a 2-inch
ring. In preparing the concrete the sand and broken stone must
be carefully washed clean immediately before being used. Then
the cement, sand and broken stone are mixed together and an
additional amount of water added by means of a spray to form
a pasty matrix, the whole being well worked over and incorpor-
ated and immediately deposited in position. It must be well
tempered. In heavy work the layers should not exceed 12
inches in thickness, and should be allowed to set for 24 hours
before the succeeding layer is deposited.

Basement floors are usually finished with a i^-inch coat of
Portland cement in the proportion of two parts cement to one
part of fine, clean, white sand, and finished with a floated sur-
face; but for heavy work the coat should be one inch in thick-
ness.

The body of the concrete should not be allowed to dry before
the finishing coat is applied.

Cement expands and contracts with changes of temperature
in the same way as iron, wood, sandstone and other materials.
From this cause, if the necessary care has not been taken in
the work, cracks will result, especially in wide surfaces. These
may be avoided by dividing the flooring into smaller blocks,
which should not exceed 4 to 5 square yards in area, and should
be separated by strips of tar paper or by sand joints % inch in
width. The joints in the concrete must correspond with those
cut in the surface layer. The division of the work into blocks
is also to be recommended in concrete walls and curbs.

If necessary, lay weeping drain round the inside of all out-
side walls, fill in over drain with brick or stone chips; then
level off the bottom of cellar to an even surface and fill in 4
inches or 6 inches of broken stone, bricks or cinders, making
the excavation enough deeper to allow this foundation below
the concrete work described.

FLOORS FOR WET CELLARS.

When water flows into a cellar and cannot be drained by
terra cotta pipe it is necessary to make a very strong floor to
resist the outside water pressure.

1st. Prepare the bottom of the cellar in the shape of a shal-
low dish with the lowest part in the center.

2d. Dig a shallow well in the center and lead all the water
to this well by cutting shallow ditches from the four corners
of the cellar and laying 2-inch drain tile to the well or fill the
ditches with loose broken stone. Keep the cellar pumped dry.

3d. Pave the cellar with hard-burned bricks, set on edge, laid
in cement mortar, working from the four sides towards the cen-

284 HANDBOOK FOR CEMENT USERS.

ter, keeping the well open in order to pump out the water.

4th. On this foundation lay the cement concrete floor.

5th. When the floor is hard plug up the hole in the center
with brick and quick-setting cement.

CONCRETE STEPS.

The following description of a method of laying concrete steps
by E. B. Clement, a practical cement worker, which appeared in
Municipal Engineering Magazine, will be of interest. For ap-
proaches to buildings, stairways, etc., the differences will be
mainly in foundations and forms.

I first had the earth removed about 20 inches, and filled the
excavation to the original surface of the ground with small
field stones, well pounded down with a large sledge. I then
put on a coat of 3 inches of coarse granite and cement and had
it well rammed down. After it had set one day and night I be-
gan the steps. I put a wide 1%-inch plank each side of the
walk, 4 feet 10 inches apart, 4 feet for the length of steps and 5
inches at each end for a side railing, and then built in the
side plank for each step, setting them 14 inches apart, though
16 inches would be better. I had these cross planks dressed and
gouged out along the edge so that each step has a 2-inch half-
round mold on it. I started the steps at the top, so that there
would be no temptation to step on them while at work. The
concrete was thoroughly w^ell tamped into place. To form the
side rails the outside plank and one 5 inches from it, cut to fit
the steps, were used. The top of this railing, which was about
6 inches high, was neatly rounded off with the trowel. In join-
ing on the rail to the steps plenty of water was kept on the steps
at each end to make it stick. The surfaces of the steps were
troweled off as soon as the planks were removed. All planks
were removed after two days. Plenty of tallow was used on
them to keep the cement from sticking. The foundation con-
crete may be one part of cement to five or six parts of gravel.
The concrete for the railing and for the outside two inches of
the steps should be quite rich in cement, say two parts of
cement to one of coarse, clean, sharp sand. The steps should be
thoroughly wet frequently for three or four days after the
forms are removed to prevent checking and cracking while tak-
ing the final set. When the surfaces are thoroughly dry, thor-
ough rubbmg with coarse sandpaper and an old rasp will give
a fine appearance to the surface. Anything built without a
solid foundation that frost, rain or sun cannot touch will be
work in vain.

CEMENT MORTAR, PHILADELPHIA.

Specifications for cement mortar for sidewalks, foundations.

SPECIFICATIONS FOR THE USE OF CEMENT. 285

masonry, etc., in Philadelphia, Pa., are as follows :

1. Sand and Water. Sand shall be sharp, silicious, dry-
screened, tide-washed bar sand or approved flint bank sand,
free from loam or other extraneous matter. The water must be
fresh and free from dirt. When so directed by the Chief Engi-
neer salt water may be required to prevent mortar from freez-
ing when absolutely necessary to lay masonry in cold weather.

2. Composition. Portland cement mortar shall be composed
of one part of cement and three parts of sand. Natural cement
mortar shall be composed of one part of cement and two parts
of sand.

Mortar for pointing, grouting, bedding, coping stones and
bridge seats, shall be composed of one part Portland cement and
two parts sand. A greater proportion of cement shall be used
when required.

3. Mixing. The ingredients, properly proportioned by meas-
urement, must be thoroughly mixed dry in a tight box of suit-
able dimensions, and the proper amount of clean water added
afterwards. No greater quantity is to be prepared than is re-
quired for immediate use, and any that has "set" shall not be
retempered or used in any way.

4. Tensile Strength. Mortar taken from the mixing box,
and molded into briquettes one square inch in cross-section,
shall develop the following ultimate tensile strengths :

7 days (1 day in air, 6 days in water), 1 part of natural cement

to 2 parts of sand .' . . . 50 Ibs.

28 days (1 day in air, 27 days in water) 1 part of natural cement

to 2 parts of sand 125 Ibs.

7 days (1 days in air, 6 days in water) 1 part of Portland cement

to 3 parts of sand 125 Ibs.

28 days (1 day in air, 27 days in water) 1 part of Portland

cement to 3 parts of sand 175 Ibs.

MORTAR AND CONCRETE, BUFFALO.

Specifications for cement mortar and concrete in Buffalo are
as follows :

Sand and Mortar. All sand used in the mortar must be
clean, sharp, coarse, lake sand, free from loam or vegetable mat-
ter. The proportion of sand and cement for natural cement
mortar will be two (2) of sand to one (1) of cement by meas-
ure. Sufficient water will be used to make a plastic mass.
Pointing mortar will be mixed, one (1) of sand to one (1) of
Portland cement. All cement mortars shall be used immedi-
ately after mixing, and any that has been mixed more than
half an hour, or has commenced to set, shall be rejected and
thrown away.

Concrete. Concrete will consist of above described quality

286 HANDBOOK FOR CEMENT USERS.

of cement, clean, sharp, coarse, lake sand, and clean stone
broken so that no dimension is larger than two (2) inches.

The cement and sand shall be mixed as required for mortar,
and then thoroughly mixed by use of shovels with broken stone,
in the proportion of one (1) cement, two (2) sand, five (5) of
broken stone immediately before using. When put in place it
will at once be leveled off, and tamped as directed by the engi-
neer, but must not be touched afterwards.

When it is impossible to finish the concrete in one day, the
surface and ends thereof to be left, and also the method of con-
tinuing such concrete to form good bond or union to be as the
engineer may direct. No masonry to be built on the concrete
until the engineer permits.

CEMENT MORTAR AND ITS USE IN SEWERS, MASONRY AND CONCRETE,

INDIANAPOLIS.

Following are the specifications for mortar for all uses, pre-
scribed by the City of Indianapolis, and the specifications for
its use in laying sewer pipe, brick masonry, plastering and con-
crete for sewers and foundations :

Mortar. 1. A rectangular box shall be provided for mixing
mortar, which, if required, shall be marked with cleats or other-
wise to give quantities of cement and sand.

2. Mortar for brick and stone masonry and concrete shall
consist of one part by measure of hydraulic cement, as speci-
fied, and two parts of clean, sharp sand, free from pebbles and
vegetable matter. When properly measured into the box the
sand and cement shall be thoroughly mixed dry until the mix-
ture shows a uniform color. When wanted for use it must be
wet with the smallest quantity of water possible, and be thor
oughly mixed and tempered. The engineer may prescribe the
number of times the mixture shall be turned over, dry and wet,
if he considers if necessary. The mortar must be used imme-
diately, and none remaining on hand so long as to have set shall
be re-mixed and used.

3. For pointing and for wet ditches the proportions shall be
one of cement to one of sand.

4. Neat cement may be required for pipe-laying in wet
ditches.

5. Mortar for plastering catch-basins and pointing outside
stone or brick masonry shall be mixed as above prescribed,
using one part of Portland cement such as specified for this
work, and one pauknljean, sharp sand, not of excessive coarse-
ness, and free from pebbles and vegetable matter.

6. In any of the above mixtures the engineer may increase
the proportions of cement for special reasons in particular

SPECIFICATIONS FOR THE USE OF CEMENT. 287

places. The proportions shall all be by measure in the mortar
box prescribed. If other methods of measurement are per-
mitted, the measurements shall be based on the measurement of
the cement in the original package, and not after being re-
moved therefrom.

Brick Sewer. The bricks shall be clean and thoroughly sat-
urated with clean water immediately before laying. Every
brick shall be neatly and truly laid in line, in full joint of mor-
tar at one operation, and in no case shall mortar be slushed or
grouted in after the brick is laid, except when so directed by
the Engineer. All brick must break joints with those in ad-
joining courses.

All joints below the springing line of the arch shall be neatly
struck, and the joints of the arch shall be cleaned off to the
face of the brick work after the centers have been removed.
The joints between the courses of the inner ring shall not be
more than one-quarter inch and the outer rings not more than
one-half inch in thickness, and between the rings or shells there
shall be one-half inch of mortar.

The centers of the intercepting sewer being struck, and all
rubbish removed from the inside of the sewer, and the whole of
the interior of the sewer being washed perfectly clean, it shall
receive, while wet, a thin : and perfectly smooth plastering of
Portland cement mortar, % inch thick, laid on with plasterer's
finishing trowel over the whole surface of the inside. This plas-
tering must not be soiled or disturbed or trodden upon for at
least forty -eight (48) hours after its application. Only inter-
cepting sewers shall be plastered.

The outside surface of all catch-basins must be covered with
cement mortar % inch thick. The inside surface shall be plas-
tered to a thickness of % inch with mortar composed of one
part of sand and one part of Portland cement.

The outside of all manholes shall be covered by a coat of
cement mortar y 2 inch thick.

Flush-tanks shall be built, plastered and tested as provided
for catch-basins and of form and dimensions shown on plans.

Pipe Sewers. Each pipe shall be laid in a firm bed and in
perfect conformity with the lines and levels given. The bottom
of the trench under each socket must be excavated so as to give
the pipe a solid bearing for its whole length. The pipes must
(if required) be fitted together and matched before lowering
into the trench, so as to secure the truest possible line on the
bottom of the inside pipes. They must be marked when in this
position and laid in the trench as marlUd. No chipping of
socket or spigot other than cutting off projections will be per-
mitted, and any pipe injured in this process shall be rejected.

288 HANDBOOK FOR CEMENT USERS.

Unless otherwise specifically ordered, the pipe shall be laid
from the lower end of the line upward. The engineer may re-
quire the pipe to be laid with level, line or straight-edge or in
other manner that will produce the result above required, and
may require that a light be set in the last manhole or lamp-
hole and each pipe laid so that this light shall always be visible
through the section of pipe under construction.

When laid in the trench as above specified, the joint shall be
completely filled with mortar of one of sand and one of cement
(see mortar specifications) in a manner fully satisfactory to
the engineer. If "he is not satisfied with the methods used by
the contractor, he may prescribe the method and the materials
to be used in filling the joints. Extra precautions shall be
taken in wet ditches. Any excess of mortar on the inside of
the pipe shall be cleaned out immediately after laying the joint.

Concrete. Broken stone shall be sound, hard limestone,
broken as nearly regular as practicable, which shall not meas-
ure more than 2% inches in any direction, and which shall be
screened through a revolving screen. It shall be free from dust,
loam or dirt. When delivered on the line of the work, it shall
be deposited on platforms made for the purpose, and the sub-
grade of pavement must be protected from injury by teams in
hauling. All stone must be crushed or broken before being
hauled upon the street, and under no circumstances will any
stone be allowed to be hauled and deposited on the street and
then broken.

Concrete for sewer work shall be composed of about 1^
measures of mortar, as specified, and four of broken stone, as
above specified, or clean, screened gravel satisfactory to the
engineer. The mortar and stone shall be so mixed in a box,
or on a platform, according to the directions of the engineer,
that every stone shall be completely covered with mortar.
It shall be laid immediately and carefully placed in layers
about six inches in thickness, and shall be settled in place by
gentle ramming, only sufficient to flush the mortar to the sur-
face. Before any layer is covered by another, its surface shall
be scored so as to make a bond between the layers.

The concrete for foundations of pavements shall be made
with Portland cement, sand and gravel. The proportions shall
be 1 part of Portland cement and 5 parts of gravel. The mor-
tar and gravel shall be so thoroughly mixed, as directed by the
engineer, that every piece of gravel shall be completely coated
with mortar. It shall then be deposited in place and rammed
until the mortar is brought to the surface.

No walking or driving over the uncovered concrete founda-
tion will be permitted, and it shall be allowed to set for eight

PECIFICATIONS FOR THE USE OF CEMENT. 289

days, or such time as the engineer may direct, before any fur-
ther work shall progress on the same. Concrete shall be planked
at street and alley crossings to permit travel to cross it with-
out injujry.

Concrete shall be sprinkled at night, when considered neces-
sary by the engineer, and he may require it to be protected from
the sun in hot weather, and from frost in cold weather, by cov-
ering with suitable material.

The thickness of concrete foundation shall be 6 inches, unless
otherwise specifically stated.

The surface of the concrete shall be parallel to the finished
surface of the street, and templets shall be used as directed by
the engineer.

The engineer shall be notified before concrete laying is begun,
and no work shall be done until he has examined and accepted
the sub-grade.

If at any time, for violation -of these specifications, any con-
crete shall, in the opinion of the engineer, prove entirely, or in
any portion, inferior, it shall be removed by the contractor and
replaced in a suitable manner.

CONCRETE SEWERS.

The city of Washington, D. C., constructs concrete sewers
under two specifications for concrete.

The materials are pebbles from fine bank or river gravel thor-
oughly screened, free from earthy or other foreign matter and
small enough to pass through a ring 1% inches in diameter;
clean, sharp sand free from mud, sewage, mica or other foreign
matter equal to samples; fresh, clean water, free from earth,
dirt or sewage ; and Portland cement furnished by the city.

Mortar for concrete masonry, class A, is made of one part of
Portland cement in perfect condition and two parts of loose,
dry sand by volume; that for class B of one part cement and
2!/2 parts of sand; thoroughly mixed dry and then enough
water added to make a stiff paste, being turned over and mixed
with shovels not less than six times, if mixed by hand, before
the water is added. Mortar must be used within an hour after
the water is added to it.

Concrete masonry of each class is made of the respective mor-
tars and pebbles, the amount of mortar to be 25 per cent, in
excess of the volume of voids in the pebbles.

The pebbles are drenched with water and added to the mor-
tar in the proportions determined for the material in use, and
the mass is thoroughly turned over not less than four times
and mixed on a water-tight platform until every particle of the

290

HANDBOOK FOR CEMENT USERS.

pebbles is completely enveloped with mortar, the work being
done as expeditiously as possible.

Concrete is lowered to place in buckets, carefully deposited
so as to keep its even mixture and free from foreign matter,
spread in horizontal layers not exceeding 5 inches in thickness,
and at once thoroughly compacted by ramming.

Strong molds, forms and centers are used, made to fit the
curves and shape of all the work and kept scraped clean from
cement and dirt.

The back of every arch is thoroughly cleaned of dirt or loose
or projecting mortar and smoothly plastered from the spring-
ing line to the crown with a coat of mortar, % in. thick. The
arches are allowed to set at least 24 hours before back-filling,
walking or working on them or any weights are applied.

The back-filling is brought up evenly on both sides of the
sewer, so that no unbalanced pressure is brought upon the
masonry. It is spread in horizontal layers not exceeding 6
inches in depth and thoroughly rammed.

Water must be kept out of the trench until the cement has set
beyond the chance of injury.

The accompanying illustration shows the method of manu-

MAKING BLOCKS FOR COLDWATER, MICH., SEWER.

SPECIFICATIONS FOR THE USE OF CEMENT. 291

facture and treatment of the concrete blocks of which the upper
arch of a sewer in Coldwater, Mich., was constructed,
the invert being laid as a monolith. The invert is
8 inches thick and the blocks were 8 inches deep by
24 inches long, and 5% inches chord on the intrados^ the sewer
being 3.5 feet in diameter. Concrete was made of 1 part Port-
land cement to 6 parts of gravel, the proportion of water be-
ing particularly important in molding the blocks, too much
water causing the concrete to stick to the molds and too little
to leave the block dry and crumbly before the cement had set.
Appearance of water on the surface after ramming indicated
proper consistency. No form was used in laying the invert, the
shape being roughly made with shovels and rammers, a float or
board held along the inside aiding in making the inside shoul-
der stand up square. A semi-circular templet drawn along the
surface gave one a half-inch larger than the finished invert, a
heavy coat of mortar, made one part of cement to two parts
of sand being troweled on while the concrete was still green and
brought to true surface by another templet.

CURING OF CEMENT BLOCKS.

The following specification for curing cement blocks is ab-
stracted from a paper by James Wimmer on this subject :

One of the most important features of block manufacture is
the curing process. A block must cure uniformly. The primal
requisite in proper curing is water and plenty of it. No stated
time can be given for beginning sprinkling, as all depends on
the atmospheric conditions. Some days it can be begun in three
hours and at other times five to eight hours must elapse before
the water can be safely applied. The moment the outer surface
begins to turn light the block needs water, and it should be sup-
plied as often as this light color is noticed. Too much water
cannot be applied, provided it is sprinkled on. This watch of
the blocks and frequent application of water should continue
for at least forty-eight hours, or until the blocks are removed
from the pallets and piled in the storage house. Lath should
be placed between the tiers of blocks and the blocks should be
sprinkled frequently for five to eight days. A hose and spray
will reach the blocks if piled as specified. This watering should
be one responsible man's business. It is very important.

FILLERS FOR BRICK PAVEMENTS.

Portland cement is now very generally used as a filler for

292 HANDBOOK FOR CEMENT USERS.

the joints in brick and other block pavements. Perhaps the
Murphy grout was the first application to this purpose, this
grout being a proprietary mixture of Portland cement and
finely ground slag high in silicate of alumina, with water and
sand in proper proportions substantially the same as used with
Portland cement.

The Indianapolis specifications for cement filler are as fol-
lows:

The joints shall then be filled as nearly as possible from
bottom to top with a paving cement or grout as specified in
the bid and contract, and according to a formula for composi-
tion and consistency of same approved by the Board of Public
Works and the Engineer. Sand may be used as a filler in alleys
when specifically stated in specifications, to be applied as di-
rected by the Engineer.

When grout is used it must be equal or superior to a
grout composed of one part of Portland cement by measure and
l 1 /^ parts of fine sand, which will pass through a 3-16-inch
mesh. It shall be of such consistency as to run readily into the
joints and shall be swept in rapidly. The pavement shall be
gone over a sufficient number of times to fill every joint. When
the foundation is of broken stone, the Engineer may require the
grout to be put on in two coats, the first coat to be of such
proportions as he may direct.

Opinions vary regarding the method of applying the grout,
some first applying a coat richer in cement than above specified
and following with one similar to that specified. Experiment
has shown that, with a broken stone foundation, likely to absorb
a coat put on too thin, the first application may be with advan-
tage of a mixture of one cement to three sand, well mixed with
sufficient water to make it run freely, and applied in small
quantities with sufficient rapidity to get it into the joints with-
out too much separation of the sand and cement. This serves
to fill the lower part of the joints and the top of the sand
cushion. When it has stood a short time, it can be followed
up with the specified mixture applied often enough to fill the
joints completely. Some cement is saved in this way, as the
joints are filled without at the same time filling a good share
of the foundation.

LINING FOR DITCHES AND AQUEDUCTS.

Portland cement has been used in California for lining irri-

SPECIFICATIONS FOR THE USE OF CEMENT. 293

gation ditches to make them more nearly water-tight. The
following is a description of the process :

In preparing for the cementing work, sand is first hauled
from nearby river beds, or washes as they are called, and
dumped along the line of the ditch where it will be required
for mortar. The laborers are boarded in temporary tent camps,
in order to be near the work as it advances. With the excep-
tion of a foreman and two trowelers day laborers are em-
ployed. A mortar-bed on wheels is drawn by a horse along the
edge of the canal, keeping pace with the plasterers. Shovelers
in advance of the plasterers clean out and even off the surface,
and a man with a hose follows- and sprinkles the surface so
that it is thoroughly wet before plastering.

The sand is not screened, but is selected to contain a good
proportion of coarse as well as fine grains and to be clean.
It is mixed on the portable bed in the proportion of one of
cement to four of sand. It is mixed with hose first dry and then
wet. The mortar is then slid down the chute onto a bed from
which the shovelers spread it along the bottom and sides as
fast as the trowelers can spread it to a surface. This coat of
plaster is generally made from 14 to 3/2-inch thick on canal
work, but on this work the coat was from % to i/4-inch thick.
Within fifteen minutes after water has been added to the mortar
the last of it is plastered on the ditch. The plastered surface
is sometimes washed over with a wash of pure cement and
water applied with a brush to make it more impervious to water.
After standing a couple of days, water is allowed in the finished
section, but is kept stagnant by means of temporary dirt dams.
From these reservoirs temporary lines of %-inch iron pipes
carry water to the mortar bed as it keeps pace with the con-
struction.

STREET RAILWAY FOUNDATIONS.

For street railway work Chicago has the following form of
concrete construction under ties and of making junctions of
track with various kinds of pavements :

Concrete. The depth should be determined by the engineer
in charge, but will vary from four to twelve inches, 'according
to the exigencies of the case, or solidity of the foundations.
The concrete width is usually one foot outside the ties at each
side, or nine feet in width for a seven-foot tie. The constituent
parts of the concrete are one part of cement, two parts of sand
sharp and four or five parts of broken stone or gravel, small
enough to pass through a two-inch ring. Mix the sand and
cement dry, and turn over four times before using water. Wet
the stone before adding it to the sand and cement and mix thor-

294

HANDBOOK FOR CEMENT USERS.

oughly on a board platform with tight joints. After spreading
concrete, ram it thoroughly, until water appears on the top,
keeping it uniform and smooth. Spread one inch of coarse
sand or gravel over the concrete for tie bed. The space between

LIGHT CONCRETE CONSTRUCTION, HARTFORD, CONN., STREET RAILWAY.

the ties should be filled with concrete, broken stone, gravel or
sand, as the engineer decides, thoroughly tamped or rolled and
brought to an even surface, ready for the paving, which should
be impervious to water.

SOLID CONCRETE CONSTRUCTION, BUFFALO STREET RAILWAY.
ING BRICK PAVEMENT.

GROUT-

Paving. In cities the paving may be Belgian b'ock, brick
concrete or asphalt, and in the suburbs ordinary ea? th is used,
if ballast of broken stone, gravel, screenings or cin lers is too
expensive.

Much trouble is occasioned by the loosening of the pavement
along the rails and over the ties. It should be laid close and

SPECIFICATIONS FOR THE USE OF CEMENT. 295

compact, with the interstices filled with paving pitch or grout,
so as to insure its being impervious. Where macadam, con-
crete or asphalt is used, there should be next the rail a toothing
of block paving of stone or brick, to prevent disturb inces of
the pavement by the rail vibration.

Fine cement is used on each side of the rail web to allow the
paving to fit against the lip of the rail. The usual depth of
Belgian blocks is six inches, and they rest on a bed of sand one
inch* deep. There should be no projection to prevent the pave-
ment from fitting close to the rail.

Concrete is much preferred abroad for foundation to broken
stone; in fact, the latter is never allowed to be used

With brick paving, the concrete should be brought to within
one inch of the bottom of the bricks, then one inch of sand,
spread very evenly, and lastly the bricks, laid very true, no
brick the least bit higher than the adjoining ones.

In Cincinnati, O., a concrete stringer 12 to 15 inches deep, 16
inches wide at bottom and 18 inches wide at top is laid, using
Portland cement and limestone. This stringer extends 9 inches
below the bottom of the 9-inch rail and is continued to surrrund
the lower flange of the rail and from 3 to 6 inches up the web
according to w r hether the pavement is brick or asphalt. The
space about the rail up to the head is filled with Poitland
cement so that the rail is completely enclosed excepting the
upper wearing surface. Cross-ties of wood are used at inter-
vals of 10 feet and steel tie bars at intervals of 5 feet. Denver
uses similar construction, with cross-ties and tie-r )ds at inter-
vals of 6 feet, concrete on one portion being made of Portland
cement 1 part and gravel and sand 5 parts, and on another por-
tion of natural hydraulic cement 1 part and gravel and sand
3 parts. The rail rests on top of the concrete beam. Detroit
uses a concrete beam extending 8 inches below the rail, which
rests on it, 12 inches 'wide at top and 8 inches wide at bottom.
Wooden or steel cross-ties are used. Several cities us? construc-
tions differing only in minor details from those named. Scran-
ton, Pa., improves upon it by using pieces of old rails for cross-
ties. Concrete is made of 1 part Portland cement, 3 parts sand
and 5 parts broken stone.

METHOD OF CONCRETING. MONIER ARCH BRIDGE, PHILADELPHIA:

After the entire mason work of the old stone bridge was
torn down to low-water mark, substantial wooden cofferdams

296 HANDBOOK FOR CEMENT USERS.

were built from rock bottom up to the elevation of the spring-
ing line of the new bridge around the center pier and both
abutments, properly anchored to ,the ground, braced, and
sheet piled at the inside and outside with clay puddle between,
to make a solid and water-tight caisson for the whole con-
creting, and at the same time to serve as support for the cen-
tering and casing of the arches; 12xl2-in. yellow pine timbers
were used for the frame work of the cofferdams and for the
adjustable trusses of the centerings, and 3-in. planks, also of
yellow pine, for the covering and sheet-piling. To prevent any

ELEVATION OF MELAN ARCH, SOUTH BEND, 1ND., AND SECTIONS OF RAIL-
ING AND ORNAMENTAL WORKS.

adhesion of the concrete to the wood-work, the corresponding
surfaces were planed, oiled and sanded. In order to discharge
the surplus water at any rate accumulated at the bottom of
the concrete after its setting, small holes about % of an inch
in diameter were made in the planks when and wherever re-
quired.

As soon as the coffer-dams were completed and all water
pumped out, the old mason work below low-water mark was
excavated to said bottom, the top surface then first thor-
oughly cleaned, wetted and slushed with neat Portland
cement; and then the first layer of concrete placed in a thick-
ness not exceeding 12 inches, so as to secure a thorough level
base for all subsequent layers, 9 inches thick, up to the
springing line of the arches, laid in uninterrupted continua-

SPECIFICATIONS FOR THE USE OF CEMENT.

297

tion, until one layer was placed always through on either
part of the bridge.

Then the arches were concreted in the same manner in sub-
sequent equal layers of concrete, each one closing 9 inches
thick at the crown. The concrete was applied from a movable
platform by regular tight mortar barrows, in equal portions
central to the arches, beginning at the haunches and continu-
ing towards the crown of the arches at the same time, so as
to secure a uniform setting of the concrete. After the first

MELAN ARCH WITH CONCRETE FACE, MISHAWAKA, IND.

setting of each layer (requiring from l 1 /^ to 2 hours after its
bedding), a subsequent layer was placed, and so on. To ob-
tain a proper binding between the layers, during high tem-
perature, the top surface of each layer was kept damp ; and
during the interruption of the work at night-time and on Sun-
days the top surface was covered with damped canvas, and
during heavy rain-storms with planks.

Wire nets, a la system "Monier," were placed between each
layer, 12 inches apart square, of ~y$-mch galvanized iron wires,
anchored by upright rods to the haunches and abutments.

SPECIFICATIONS FOR MELAN ARCH BRIDGE AT TOPEKA, KANSAS.

Plans. The work shall be constructed complete in accord-
ance with the general plans, sections and diagrams herewith
submitted, and these specifications. The specifications and
drawings are intended to describe and provide for the com-

298 HANDBOOK FOR CEMENT USERS.

plete work. They are intended to be co-operative, and what
is called for by either is as binding as if called for by both.
The work herein described is to be completed in every detail,
notwitstanding that every item necessarily involved is not
particularly mentioned. The contract price shall be based
upon these specifications and drawings, which are hereby
signed and made a part of the contract.
Conditions of Calculation.

Modulus of elasticity of concrete 1,400,000 Ibs.

Modulus of elasticity of steel 28,000,000 Ibs.

Maximum stress per square inch on steel 10,000 Ibs.

Maximum compression per square inch on con-
crete 500 Ibs.

Maximum shear per square inch on concrete .... 100 Ibs.

Maximum tension per square inch on concrete. . 50 Ibs.

The above are to be exclusive of temperature stresses. The
steel ribs under a stress not exceeding their elastic limit
must be capable of taking the entire bending moment of the
arch, without aid from the concrete, and have a flange area
of not less than 1-150 part of the section of concrete at
crown.

Discrepancies. In the event of any discrepancies between
the drawings and the figures written on them, the figures are
to be taken as correct, and in cases of any discrepancy between
the drawings and the specifications, the specifications are to be
adhered to.

Foundations. All foundations shall be shown on plans,
and conform to the dimensions marked thereon. Foundations
on rock shall be prepared by removing all sand, mud or other
soft material, and by excavating the bed rock in such manner
as may be described or shown on drawings. Foundations on
hardpan, gravel and clay, cemented sand, or other material
intended to carry the load without piles, shall be excavated
to the depths shown on plans.

Foundations on piles, when not otherwise described, shall
be inclosed in a permanent coffer-dam or crib, and be exca-
vated to the depths shown on plans, and the piles shall be
driven after the excavations are made. The spaces between
the piles shall be filled with concrete, and in case it is found
necessary to lay the concrete under water proper appliances
must be used to insure its being deposited with as little in-
jury as possible. The piles shall be oak, yellow pine or other
wood that will stand the blow of the hammer, straight, sound
and cut from live timber, trimmed close, cut off square at the
butt, and have all bark taken off. The piles shall not be less
than 12 inches nor more than 16 inches in diameter at the

SPECIFICATIONS FOR THE USE OF CEMENT. 299

large end,, nor less than 10 inches in diameter at the small
end for piles having a length of 30 feet and under. For
greater lengths the diameter of small end may be reduced 1
inch for each 10 feet of additional length down to a minimum
of 7 inches. The piles shall not be loaded with a weight
greater than given by the following formula: L=2wh-*-
(s+ 1), in which L=safe load in pounds; w = weight of ham-
mer in pounds, h= fall of hammer in feet, s = last penetra-
tion in inches. The number and arrangement of the piles for
each foundation shall be shown on plans, and they shall be
sawed off at the elevation shown.

Cement. The cement shall be a true Portland cement,
made by calcining a proper mixture of calcareous and clayey
earths; and if required, the contractor shall furnish a certi-
fied statement of the chemical composition of the cement,
and the raw materials from which it is manufactured. The
fineness of the cement shall be such that at least 99 per cent,
will pass through a sieve of 50 meshes per lineal inch, at least
90 per cent, will pass through a sieve of 100 meshes per lineal
inch, and at least 70 per cent, will pass through a sieve of 200
meshes per lineal inch.

Samples for testing may be taken from each and every
barrel delivered, unless otherwise specified. Tensile tests
will be made on specimens prepared and maintained until
tested at a temperature of not less than 60 degrees F. Each
specimen will have an area of 1 square inch at the breaking
section, and after being allowed to harden in moist air for 24
hours, will be immersed and maintained under the water
until tested. The sand used in preparing the test specimens
shall be clean, sharp, crushed quartz, retained on a sieve of
30 meshes per lineal inch. No more than 23 to 27 per cent,
of water shall be used in preparing the test speciments of neat
cement, and in the case of test specimens of 1 cement and 3
sand, no more than 11 or 12 per cent, of water by weight shall
be used.

Specimens prepared from neat cement shall after seven
days develop a tensile strength of not less than 450 Ibs. per
square inch. Specimens prepared from a mixture of 1 part
cement and 3 parts sand, parts by weight, shall after seven
days develop a tensile strength of not less than 160 Ibs. per
square inch, and not less than 220 Ibs. per square inch after
28 days. Specimens prepared from a mixture of 1 part cement
and 3 parts sand, parts by weight, and immersed after 24
hours in water maintained at 176 degrees F., shall not swell
nor crack, and shall, after seven days, develop a tensile
strength of not less than 160 Ibs. per square inch. Cement

300 HANDBOOK FOR CEMENT USERS.

mixed neat with about 27 per cent, of water to form a stiff
paste, shall after 30 minutes be appreciably indented by the
end of a wire 1-12 inch in diameter loaded to weigh 14 Ib
Cement made into thin cakes on glass plates, shall not crack,
scale or warp under the following treatment: Three pats
will be made and allowed to harden in moist air at from 60
degrees to 70 degrees F. ; one of these will be subjected to
water vapor at 176 degrees F. for three hours, after w r hich
it shall be immersed in hot water for 48 hours; another shall
be placed in water at from 60 degrees to 70 degrees F., and
the third shall be left in moist air. All cement shall be kept
housed and dry until wanted in the work.

Portland Cement Concrete. The concrete shall be com-
posed of clean, hard broken stone, or gravel, with irregular
surface; clean, sharp sand, and cement, mixed in the propor-
tions hereafter specified. Whenever the amount of work to
be done is sufficient to justify it, approved mixing machines
shall be used. The ingredients shall be placed in the machine
in a dry state, and in the volumes specified, and be thoroughly
mixed, after which clean water shall be added and the mixing
continued until the wet mixture is thorough and the mass
uniform. No more water shall be used than the concrete
will bear without quaking in ramming. The mixing must be
done as rapidly as possible and the batch deposited in the
work without delay.

If the mixing is done by hand, the cement and sand shall
first be thoroughly mixed dry in the proportions specified.
The stone previously drenched with water shall then be de-
posited on this mixture. Clean water shall be added and the
mass be thoroughly mixed and turned over until each stone
is covered with mortar, and the batch shall be deposited
without delay, and be thoroughly rammed until all voids are
filled. The grades of concrete to be used are as follows:
For the arches between skewbacks 1 part Portland cement,
2 parts sand and 4 parts broken stone, or gravel, that will
pass through a 1%-inch ring; for the foundations, abutments,
piers and spandrels 1 part Portland cement, 4 parts sand
and 8 parts broken stone or gravel, that will pass through a
2-inch ring.

Concrete Facing. If concrete facing is used it shall be
composed of 1 part Portland cement and 2*/ 2 parts sand, and
shall have a thickness of at least 1 inch on all arch soffits,
arch faces, abutments, piers, spandrels or other exposed sur-
faces. There must be no definite plane or surface of dernark-
ation between the facing and the concrete backing. The
facing and backing must be deposited in the same layer, and

SPECIFICATIONS FOR THE USE OF CEMENT. 301

be well ramnied in place at the same time. If the arch faces,
quoins or other exposed surfaces are marked tp represent
masonry, such division marks shall be made by triangular
strips 2 inches wide and 1 inch deep fastened to the casing in
perfectly straight and parallel lines, and all projecting cor-
ners will be beveled to correspond.

Plastering. No plastering will be allowed on the exposed
faces of the work, but the inside faces of the spandrel walls
covered by the fill may be plastered with mortar having the
same, composition as specified for facing.

Stone Facing. If stone facing is used the ring stones, cor-
nices and faces of spandrels, piers and abutments shall be
of an approved quality of stone. The stone must be of a
compact texture, free from loose seams, flaws, discolorations
or imperfections of any kind, and of such a character as will
stand the action of the weather. The spandrel walls will be
backed with concrete, or rubble masonry, to the thickness re-
quired. The stone facing shall in all cases be securely bonded
or clamped to the backing. All stone shall be rock-faced
with the exception of cornices and string courses, which
shall be sawed or bush-hammered. The ring stones shall be
dressed to true radial lines, and laid in Portland cement mor-
tar, with 14-inch joints. All other stones shall be dressed to
true beds and vertical joints. * No joints shall exceed y 2 inch
in thickness, and shall be laid to break joints at least 9
inches with the course below. All joints shall be cleaned,
wet and neatly pointed. The faces of the walls shall be laid
in true line, and to the dimensions given on plans, and the
corners shall have a chisel draft 1 inch wide carried up to
the springing lines of the arch, or string course. All cornices,
moldings, capitals, keystones, brackets, etc., shall be built into
the work in the proper positions, etc., and shall be of the forms
and dimensions shown on plans.

Brick Facing with Concrete Trimmings. The arch rings,
cornices, string courses and quoins, shall be concrete-faced
as described above, the arch rings and quoins being marked
and leveled to represent masonry. The piers, abutments and
spandrels shall be faced with vitrified brick as shown on
plans. The brick facing shall be plain below the springing
lines of the arches, and rock-faced above these lines. All
rock-faced brick shall be chipped by hand from true pitch
lines. All brick facing shall be bonded as shown on plans,
at least one-fifth of the face of the wall being headers. The
brick must be of the best quality of hard-burned paving brick,
and must stand all tests as to durability and fitness required
by the engineer in charge. The bricks must be regular in

302 HANDBOOK FOR CEMENT USERS.

shape and practically uniform in size and color. They shall
be free from lime and other impurities; shall be free from
checks or fire cracks, and as nearly uniform in every respect
as possible; shall be burned so as to secure the maximum
hardness; so annealed as to reach the ultimate degree of
toughness; and be thoroughly vitrified so as to make a homo-
geneous mass. The backing shall be carried up simulta-
neously with the face work, and be thoroughly bonded
with it.

Artificial Stone. All keystones, brackets, consoles, den-
tils, pedestals, hand-railing posts and panels and other orna-
mental work when used, also curbs and gutters, shall be of
the design shown on plans, and be molded in suitable molds.
The mortar for at least 1 inch thick shall consists of 1 part
Portland cement and 2% parts sand, and when the size of the
molding will admit, the interior may be composed of con-
crete of the same composition as specified for the arches. When
pedestals, posts or panels carry lampposts a 4-inch wrought-
iron pipe shall be built into the concrete from top to bottom,
and at bottom shall be connected with a 3-inch pipe extending
under the sidewalk, and connected with a gaspipe or electric
wire conduit. The pipes shall have no sharp bends, all changes
in direction being made by gentle curves.

Sprinkling. During warm and dry weather all newly built
concrete shall be well sprinkled with water for several days, or
until it is well set.

Mixtures. The volumes of cement, sand and broken stone in
all mixtures of mortar or concrete used in the work shall be
measured loose.

Connections. In connecting concrete already set with new
concrete the surface shall be cleaned and roughened, and
mopped with a mortar composed of 1 part Portland cement and
1 part sand, to cement the parts together.

Arches. The concrete for the arches shall be started simul-
taneously from both ends of the arch, and be built in longi-
tudinal sections wide enough to inclose at least two steel ribs,
and of sufficient width to constitute a day's work. The con-
crete shall be deposited in layers, each layer being well rammed
in place before the previously deposited layer has had time to
set partially. The work shall proceed continuously day and
night, if necessary, to complete each longitudinal section.
These sections while being built shall be held in place by sub-
stantial timber forms, normal to the centering and parallel
to each other, and these forms shall be removed when the sec-
tion has set sufficiently to admit of it. The sections shall be

SPECIFICATIONS FOR THE USE OF CEMENT. 303

connected as specified above, and also by steel clamps or rib
connections built into the concrete.

Drainage. Provision for drainage shall be made at each pier
as follows: A wrought-iron pipe of sufficient diameter squill
be built into the concrete, extending from the center of each
space over pier to the soffit. The surface of concrete over piers
shall be so formed that any water that may seep through fill
above will be drained to the pipes. The line of drainage will be
covered with a layer of broken stones, and the top of pipes will
be provided with screens to prevent clogging.

Steel Ribs. Steel ribs shall be imbedded in the concrete of
the arch. They shall be spaced at equal distances apart, and be
of the number shown on plans. Each rib shall consist of two flat
bars of the sizes marked on plans. The bars shall be in lengths
of about 30 feet, thoroughly spliced together, and extending
into the abutments as shown. Through the center of each bar
shall be driven a line of rivets spaced 8 inches, c. to c., with
heads projecting about % inch from each face of bar, except
through splice plates, where ordinary heads will be used. The
bars shall be in pairs with their centers placed 2 inches within
the inner and outer lines of the arch respectively as shown.
All steel must be free from paint and oil, and all scale and rust
must be removed before imbedding in the concrete.

The tensile strength, limit of elasticity and ductility shall be
determined from a standard test piece cut from the finished
material and turned or planed parallel. The area of cross-
section shall not be less than y 2 square inch. The elongation
shall be measured after breaking on an original length of 8
inches. Each melt shall be tested for tension and bending.
Test pieces from finished material prepared as above described
shall have an ultimate strength of from 60,000 to 68,000 Ibs.
per square inch ; an elastic limit of not less than one-half of the
ultimate, shall elongate not less than 20 per cent, in 8 inches,
and show a reduction of area at point of fracture of not less
than 40 per cent. It must bend cold 180 degrees around a
curve whose diameter is equal to the thickness of piece tested
without crack or flaw on convex side of bend. In tension tests
the fracture must be entirely silky.

Rivet Steel. Test. pieces from finished material, prepared
as above described, shall have an ultimate strength of from
54,000 to 62,000 Ibs. per square inch, an elastic limit of not less
than one-half of the ultimate strength, shall elongate not less
than 20 per cent, in 8 inches, and show a reduction at point of
fracture of not less than 50 per cent. It must bend cold 180
degrees and close down on itself without fracture on convex
side of bend. In tension tests the fracture must be entirely
silky.

304 HANDBOOK FOR CEMENT USERS.

Inspection. The contractor shall furnish a testing machine
of the proper capacity and shall prepare and test without
charge such specimens of steel as may be required to prove that
it comes up to the requirements mentioned above.

Workmanship. The rivet holes for splice plates of abutting
members shall be so accurately spaced that when the members
are brought into position the holes shall be truly opposite be-
fore the rivets are driven. When members are connected by
bolts the holes must be reamed parallel and the bolts turned to
a driving fit. Rivets must completely fill the holes, have full
heads concentric with the rivets, and be machine driven when
practicable.

Centering. The contractor shall build an unyielding false
work or centering. The lagging shall be dressed to a uniform
size so that when laid it shall present a smooth surface, and
this surface shall conform to the lines shown on the drawings.
The center shall not be struck until at least 28 days after the
completion of the arch. Great care shall be used in lowering
the centers so as not to throw undue strains upon the arches.
The tendency of the centers to rise at the crown as they are
loaded at the haunches must be provided for in the design, or,
if not, the centers must be temporarily loaded at the crown,
and the load be so regulated as to prevent distortion of the
arch as the work progresses.

Casing. When concrete facing is used all piers, abutments
and spandrel walls shall be built in timber forms. These forms
shall be substantial and unyielding, of the proper dimensions
for the work intended, and all parts in contact with exposed
faces of concrete 'shall be finished to a perfectly smooth sur-
face, by plastering or other means, so that no mark or imper-
fection shall be left on the work.

Waterproofing. After the completion of the arches and
spandrels, and before any fill is put in, the top surface of
arches, piers and abutments and the lower 6 inches of the
inner surface of the spandrel walls shall be covered with a
suitable waterproof material, so as to exclude water effectually.

Fill. The space between spandrel walls shall be filled with
sand, earth, cinders or other suitable material, and be thor-
oughly compacted by ramming, steam road roller, saturating
with water or other effective means, and be finished to the
proper grade to receive the curbing and pavement.

Granitoid Sideivalks. The spaces over which the sidewalks
are to be laid shall first be covered with 6 inches of cinders
well compacted. On this shall be laid 4 inches of concrete, con-
sisting of 1 part Portland cement, 3 parts sand and 6 parts
broken stone or gravel small size well rammed. The flag

SPECIFICATIONS FOR THE USE OF CEMENT. 305

divisions shall then be marked off to the desired size. On the
surface of the concrete shall then be laid a wearing surface 1
inch thick, composed of 2 parts Portland cement and 3. parts
broken granite or other acceptable stone, in size from % inch
downward. It shall be well rammed and troweled to a per-
fectly even surface and rolled with a toothed roller. This wear-
ing surface must be spread on the concrete while the latter is
still soft and adhesive, and neat connections must be made
with cornices and curbs.

Roadway Pavement. The pavement shall be of the kind
shown on plans or mentioned in proposal, and shall be built
according to the specifications adopted in the locality where
used, unless otherwise mentioned.

Retaining Stone. There shall be set at each end of roadway
pavement a line of stones of approved quality, 4 inches in thick-
ness and 18 inches deep, with top surface conforming to contour
of pavement.

Balustrades and Hand-Railings. The balustrades shall be
of the material and of the form and dimensions shown on plans,
and shall be brought to true alignment and be firmly fastened
to the outside of each sidewalk in the position shown. If an
iron hand-railing is used, it shall receive two coats of approved
paint after erection.

Erection. The contractor shall employ suitable labor for
every kind of work, and all stone work shall be laid by com-
petent masons. The contractor will furnish all staging, piling,
cribbing, centering, casing and material of every description
required for the erection of the work ; also all plant, including
dredges, engines, pumps, derricks, barges, mixing machines,
pile drivers, conveyors or other appliances necessary for carry-
ing on all parts of the work. The contractor shall assume all
risks for loss or damage incurred by ice, floods, fire or other
causes during the construction of the work, and shall suf-
ciently watch and light the work at night during construction.

Cleaning Up. Upon completion of work, and before final
acceptance thereof, the contractor shall remove all temporary
work from the river and all rubbish from the streets.

Maintaining Public Travel. If public travel is to be main-
tained during the construction of the new bridge by the re-
moval of old bridge, construction of temporary bridge or other-
wise, special mention of the same shall be made.

Removal of Old Bridge. If the site of the proposed structure
is occupied by an old bridge, the same shall be removed by the
contractor. The iron work shall be piled on the bank and the
timber and stone shall become the property of the contractor.

Work Embraced by Contract. The work embraced by con-

306 HANDBOOK FOR CEMENT USERS.

tract will be for the 'structure complete from out to out of abut-
ments or retaining walls, as per plans and specifications, and
will embrace fill, pavement, sidewalks and balustrades com-
plete for this length.

Approaches. The approaches will commence where the work
above mentioned ends, and if all or any part of them is in-
cluded in contract the same shall be specially mentioned.

Changes. The committee in charge shall have power to di-
rect changes which they may consider necessary or advisable
in any part of the work, and such changes shall not in any way
violate the contract, but the value of such changes shall be
added to or deducted from the contract price, and any dispute
as to their value shall be settled by arbitration in the usual
way.

Inspection. All material furnished by the contractor shall
be subjected to the inspection and approval of the committee
in charge.

Lamp Posts, Trolley Poles and Name Plates. If used these
shall be shown on plans, or be specially mentioned.

Interpretation of Plans and Specifications. The decision
of the committee in charge or their engineer shall control as
to the interpretations of drawings and specifications during
the execution of the work thereunder, but this shall not de-
prive the contractor of his rights to redress, after the com-
pletion of the work, for any improper orders or decisions.

Estimates. Approximate estimates of work done and ma-
terial delivered shall be made on or about the last day of ev-
ery month, and a valuation of the same in proportion to con-
tract prices for the completed work will be made by the com-
mittee in charge or their engineer, which sum shall be paid
to the contractor in cash, on or about the 10th day of the fol-
lowing month, less a deduction of 10 per cent, upon said val-
ation, which shall be retained until the final completion of
the work.

Final Payment. Upon the final completion of the work the
contractor shall be promptly paid any balance of the contract
price which shall then remain due and unpaid.

One significant change in specifications since the above were
written in 1900 is seen in the requirement by Marion County,
Indiana, for similar bridges designed in 1904, that concrete
shall be mixed by machine and that hand mixing will not be
permitted. This change is very general, the improvement in
mixing machines making their use imperative on work of any
great extent, on account of both thoroughness and economy.

SPECIFICATIONS FOR THE USE OF CEMENT. 307

SPECIFICATIONS FOR REINFORCED CONCRETE ARCHES IN
INDIANAPOLIS, 1ND.

The following provisions are from the specifications for rein-
forced concrete arches in Indianapolis, Ind., in force in 1904
and 1905. They differ from those given in previous editions
of this book only in the way of simplification and in such items
as the requirement of machine mixing, which show the develop-
ments in methods of operation.

1. Plans. The work shall be constructed complete in accord-
ance with the general plans, sections and diagrams herewith
submitted and these specifications.

The specifications and drawings are intended to describe and
provide for the complete work. They are intended to be co-
operative, and what is called for by either is as binding as if
called for by both. The work herein described is to be com-
pleted in every detail, notwithstanding that every item neces-
sarily involved is not particularly mentioned. The contract
price shall be based upon the specifications and drawings, which
are hereby signed and made a part of the contract.
Conditions of Calculation.

Modulus of elasticity of concrete 1,400,000 Ibs.

Modulus of elasticity of steel .28,000,000 Ibs.

Maximum stress per square inch of steel 10,000 Ibs.

Maximum compression per square inch on con-
crete 500 Ibs.

Maximum shear per square inch on concrete. . . . 100 Ibs.

Maximum tension per square inch on concrete. . 50 Ibs.

(The above to be exclusive of temperature stresses.)

The steel ribu under a stress not exceeding their elastic limit
must be capable of taking the entire bending moment of the
arch without aid from the concrete, and have a flange area of
not less than 1-150 part of the section of concrete at crown.

2. Discrepancies. In the event of any discrepancies between
the drawings and the figures written on them, the figures are
to be taken as correct, and in case of any discrepancy between
the drawings and the specifications, the specifications are to
be adhered to.

3. Foundations. All foundations are shown on plans and
must conform to dimensions marked thereon. Foundations on
piles when not otherwise described, shall be enclosed in a per-
manent coffer-dam or crib, and be excavated to the depths
shown on plans, and the piles shall be driven after the exca-
vations are made. The spaces between the piles shall be filled
with concrete, and in case it is found necessary to lay the con-
crete under water, proper appliances must be used to insure

308 HANDBOOK FOR CEMENT USERS.

its being deposited with as little varying as possible. The
piles shall be oak, yellow pine, or other wood that will stand
the blow of the hammer, straight, sound, and cut from live
timber, trimmed close, cut off square at the butt and have all
bark taken off. The piles shall not be less than 12 nor more
than 16 inches in diameter at the large end, nor less than 10
inches in diameter at the small end. The number and arrange-
ment of the piles for each foundation shall be shown on plans
and they shall be sawed off at the elevation shown.

4. For cement specifications, see chapter on Specifications
for Cement.

5. Concrete. The concrete shall be composed of clean, hard
broken stone or gravel, with irregular surface, clean, sharp
sand and Portland cement, mixed in the proportions herein-
after specified. Approved mixing machines shall be used. The
ingredients shall be placed in the machine in a dry state and
in the volumes specified, and be thoroughly mixed, after which
clean water shall be added and the mixing continued until
the wet mixture is thorough and the mass uniform. No more
water shall be used than the concrete will bear without quak-
ing in ramming. The mixing must be done as rapidly as pos-
sibe and the batch deposited on the work without delay.

The grades of concrete to be used are as follows: For the
arches between skewbacks: 1 part Portland cement, 2 parts
sand and 4 parts gravel that w r ill pass through a 1% inch ring ;
for the foundation, abutments, piles and spandrels: 1 part
Portland cement, 3 parts sand and 6 parts broken stone or
gravel that will pass through a 2-inch ring.

6. Stone Facing. The ring stones, cornices and faces of
spandrels, piers and abutments shall be of the best Bedford
stone. The stone must be of a compact texture, free from loose
seams, flaws, discolorations, or imperfections of any kind, and
of such character as will stand the action of the weather. The
spandrel walls will be backed with concrete or rubble masonry
to the thickness required. The stone facing shall in all cases be
securely bonded or clamped to the backing. All stones shall
be rock-faced with the exception of cornices, ring stones, rail-
ing and string courses, which shall be sawed or planed. The
ring stones shall be dressed to true radial lines and laid in
Portland cement mortar with i/i-inch joints. All other stones
to be dressed to true beds and vertical joints. No joints shall ex-
ceed one-half of an inch in thickness and shall be laid to break
joints at least 9 inches with the course below. All joints
shall be cleaned, wet and neatly pointed. The faces of the
walls shall be laid on true lines and to the dimensions given
on plan, and the corners shall have a chisel draft one inch wide
carried up to the springing line of the arch, or string course.

SPECIFICATIONS FOR THE USE OF CEMENT. 309

All cornices, capitals, moldings, keystones, brackets, etc., shall
be built into the work in proper position and shall be of the
forms and dimensions shown on plan and according to detail
plans to be furnished.

7. Sprinkling. During dry and warm weather all newly
built concrete shall be kept well sprinkled with water for sev-
eral days, or until it is well set.

8. Mixtures. The volumes of cement, sand and broken stone
in all mixtures of mortar or cement used in the work shall be
measured loose.

9. Connections. In connecting concrete already set with
new concrete the surface shall be cleaned and roughened, and
mopped with a mortar composed of 1 part Portland cement and
1 part sand, to cement the parts together.

10. Arches. The concrete for the arches shall be started
simultaneously from both ends of the arch and shall be built
in longitudinal sections wide enough at least to include two
steel ribs and of sufficient width to constitute a day's work.
The concrete shall be deposited in layers, each layer being well
rammed in place before the previously deposited layers shall
have had time to set partially. The work shall proceed day
and night continuously if necessary to complete each longi-
tudinal section. The sections while being built shall be held
in place by substantial timber forms normal to the centering
and these forms shall be removed when the section has set suffi-
ciently to admit of it. The sections shall be connected as spe-
cified above and also by steel clamps or rib connections built
into the concrete.

11. Drainage. Provision for drainage shall be made at each
pier as follows: A wrought-iron pipe of sufficient diameter
shall be built into the concrete, extending from each space over
pier to the soffit. The surface of concrete over piers shall be
so formed that any water that may seep through fill above will
be drained to the pipes. The line of drainage will be covered
with a layer of broken stone and the top of the pipes will be
provided with screens to prevent clogging.

12. Steel Ribs. Steel ribs shall be embedded in the concrete
of the arch. They shall be placed at equal distances apart,
and be of the number shown on plans. All steel must be free
from paint and oil and all scale and rust must be removed be-
fore embedding in the concrete. The tensile strength, limit of
elasticity and ductility shall be determined from a standard
test piece cut from the finished material and turned or planed
parallel. The area of cross section shall not be less than
y 2 inch. The elongation shall be measured after breaking on

310 HANDBOOK FOR CEMENT USERS.

an original length of 8 inches. Each melt shall be tested for
tension and bonding.

Tests pieces from finished material prepared as above shall
have an ultimate strength of from 60,000 to 68,000 pounds per
square inch, an elastic limit of not less than one-half the ulti-
mate, shall elongate not less than 20 per cent, in 8 inches, and
show a reduction of area at point of fracture of not less than 40
per cent. It must bend cold 180 degrees around a curve whose
diameter is equal to the thickness of the piece tested, without
crack or flaw on convex side of bend. In tension tests the
fracture must be entirely silky.

13. Rivet Steel. Test pieces for finished material, prepared
as above described, shall have an ultimate strength of from
54,000 to 62,000 pounds per square inch, an elastic limit of
not less than half the ultimate strength, shall elongate not less
than 20 per cent, in 8 inches and show a reduction at point of
fracture of not less than 50 per cent. It must bend cold 180
degrees and close down on itself without fracture on convex
side of bend. In tension tests the fracture must be entirely
silky.

14. Centering. The contractor shall build an unyielding
false work or centering. The lagging shall be dressed to uni-
form size so that when laid it shall present a smooth surf ace, and
this surface shall conform to the lines shown on the drawings.
The center shall not be struck until at least 28 days after the
completion of the work. Great care shall be shown when low-
ering the center so as not to throw undue strains upon the
arches. The tendency of the centers to rise at the crown as they
are lowered at the haunches must be provided for in the de-
sign, or if not, the centers must be temporarily loaded at the
crown and the load be so regulated as to prevent distortion of
the arch as the work progresses.

15. Facing. When concrete facing is used, all piers, abut-
ments and spandrel walls shall be built in timber forms. These
forms shall be substantial and unyielding, of the proper dimen-
sions for the work intended, and all parts in contact with ex-
posed faces of concrete shall be finished to a perfectly smooth
surface, by plastering or other means, so that no mark or im-
perfection shall be left on the work.

16. Waterproofing. After the completion of the arches and
spandrels and before any fill is put in, the top surface of the
arches, piles and abutments and the lower 6 inches of the
spandrel walls shall be covered with a suitable water-proof ma-
terial so as to exclude water effectually.

17. Fill. The space between the spandrel walls will be
filled with sand, earth, cinders or other suitable material and

SPECIFICATIONS FOR THE USE OF CEMENT.

311

be thoroughly compacted by ramming, steam road roller, satur-
ating with water or other effective means and be finished to the
proper grade to receive the curbing and pavements.

18 to 20. Paving. All curbing, sidewalks and asphalt pav-

REINFORCED CONCRETE AQUEDUCT OF INDIANAPOLIS WATER COMPANY.

ing shall be executed according to the plans and according to
the standard specifications on file in the office of the Board of
Public Works.

REINFORCED CONCRETE GIRDERS.

The Forest Park bridge for the Wabash railway in St.
Louis, Mo., was greatly limited as to cost and the design pro-
vided for reinforced concrete abutments and curved wing walls,
the cost of which could be reduced to a minimum ; the fact that
it is a bridge over a roadway aiding by reducing the necessary
foundation. The overhead structure is a through plate gir-
der with reinforced concrete slab floor, the girders being hidden
from view from the roadway by ornamental reinforced con-
crete girders supported from the main girder. The specifica-
tions for the abutments require 1 :2 :5 broken stone concrete
reinforced with Johnson bars, and the abutment is a vertical
wall about 2 feet thick, with horizontal reinforcing bars spaced
to suit the stresses and vertical bars every two feet. This
wall is set on and thoroughly connected to a floor with double
reinforcement, about 15 feet wide and projecting 2 feet outside
the wall. It is also connected with the floor by buttresses
about 8.5 feet long at the bottom and reducing to length suffi-

312 HANDBOOK FOR CEMENT USERS.

cient to carry the seat for the plate girders. These buttresses
are thoroughly bonded to the wall and are about 14 feet apart.
The wing walls are of similar construction, reducing in height
and curving to ornamental pier lamp posts. The filling on the
floor of the abutment furnishes weight for holding it in place
and resisting the thrust of the earth pressure. For forming the
vertical faces 2 by 6-inch studding was set up on proper batter
and 7 /Q-mch dressed tongued and grooved lumber was nailed to
it. The panels and the ashlar corners were provided for by
setting the dressed form boards forward on strips or setting
them back as required.

The floor of the bridge is made of slabs 8 inches thick, sup-
ported on the steel floor beams, each slab being reinforced with
two sets of corrugated bars near upper and lower surfaces.
The bars were supported and kept in proper spacing during
construction by means of notched boards of proper height, set
at the ends of the slab.

In constructing the ornamental girder, the reinforced con-
crete floor was first laid between the brackets. When this had
set the forms were set for the ornamental solid paneled part
of the girder. The studding was 2 by 4-inch lumber lined
with matched and planed lumber with added layers and
molded strips to give the panels and the molded edges their
proper form. The form was filled with 1 to 3 mortar in which
were embedded corrugated bars as reinforcement to carry the
weight of the concrete from bracket to bracket. The railing
on top of this girder was constructed separately. The balus-
ters were cast in plaster molds made by forming a box about a
wooden model and filling it with a wet mixture of 1 part plas-
ter of paris and 1 part Portland cement. This cast was divided
into three pieces by three sheets of galvanized metal inserted
in the mold box for this purpose. When fully set the inside
surface of the plaster mold was covered with a coat of shellac.
This mold being assembled, a i/^-inch corrugated rod was set
Vertically in the center and a 1 :3 Portland cement mortar
mixed wet was poured in and allowed to harden. The orna-
mental urns and balls were made in similar molds. The rail-
ing posts at the quarter points, forming panels in the railing,
were molded in three sections and then set in place. Those

SPECIFICATIONS FOR THE USE OF CEMENT. 313

at the ends were molded in place, seven separate sections and
operations being required to complete the design. The hand
rail was cast in sections and set in place.

The cost of the ornamental girders was about $1,000, made
up as follows : Balusters, 60 cents each ; intermediate posts
with urns, $12 each; end posts, $75 each; hand rail, 40 cents a
linear foot; railing base, 45 cents; frieze and coping, $2 a lin-
ear foot ; floor, 25 cents a square foot.

The River Avenue bridge over White River at Indianapolis,
Irid., built by the Marion County Commissioners, is of similar
design to the above, except that it has five 80-foot spans, has
a 40-foot roadway with double street car tracks between the
plate girders and the ornamental concrete girders are outside
of and in part support 8-foot concrete sidewalks. The follow-
ing extracts are made from the specifications:

Concrete Girders. The concrete girders for sidewalks shall
be of a size and design shown on plans. The concrete to be of
a quality hereinafter specified, and shall be reinforced with
corrugated bars.

Sidewalks. The sidewalks shall be of reinforced concrete
and shall be laid in a manner satisfactory to the engineer.

Roadway. The roadway shall be of reinforced concrete and
paved with first-class vitirfied brick upon a two (2) inch cush-
ion of sand. The quality and laying of the brifk to be in ac-
cordance with specifications used by the City of Indianapolis.

Joist Seats. The joist seats and mud walls shall be of con-
crete, as shown on drawings.

Balustrade. The balustrade shall be molded in sections and
placed in position after they are thoroughly seasoned, all joints
to be neatly pointed with Portland cement mortar, the proper
expansion joints to be provided for, as shown on drawings.

Buttresses. The buttresses over the piers shall be molded in
proper forms and be of the design shown on drawings.

Concrete. The concrete for the various parts of the work
to be as follows :

For the girders, to be a mortar of one (1) part Portland ce-
ment and three (3) parts clean, sharp sand.

For the sidewalks, one (1) part Portland cement, one and
one-half (I 1 /?) parts clean, sharp sand and two and one-half
(2i/o) parts "crushed gravel that will pass through a one-half
(i/>) inch ring.

For the roadway, one (1) part Portland cement, two (2)

SPECIFICATIONS FOR THE USE OF CEMENT. 315

parts clean, sharp sand and four (4) parts crushed gravel that
will pass through a one (1) inch ring.

For the pedestals, buttresses and balustrade, one (1) part
Portland cement, one and one-half (l 1 /^) parts clean, sharp
sand and two and one-half (2y 2 ) parts crushed gravel that will
pass through a one (1) inch ring.

For the joist seats and mud walls, one (1) part Portland ce-
ment, three (3) parts clean, sharp sand and five (5) parts
gravel that will pass through a two and one-half (2%) inch
ring.

All concrete to be machine mixed and placed in position
in a manner satisfactory to the engineer. All materials to be
measured loose and proportioned as above specified.

Mortar Facing. All concrete surfaces exposed to view or
to the weather shall have a mortar face of a minimum thick-
ness of one (1) inch. The mortar facing must in every case be
built up with the concrete, and no plane of demarcation or any
plastering will be allowed. The mortar shall be composed of
one (1) part Portland cement and two and one-half (2y 2 )
parts sand, measured loose.

Steel Bars. All steel bars used for reinforcing concrete shall
be corrugated, and of a size and design shown on the drawings ;
must be free from rust, scale or oil, and be spaced as shown on
plans.

Forms. The contractor shall build substantial forms for the
roadway and sidewalks, the same to be properly braced and in
conformity to the lines shown on drawings.

Casing. The forms for casing all concrete work shall be
substantial and of timber of such thickness and stiffness and
so braced that they are unyielding when the concrete is placed
and rammed next to them. The forms for the various concrete
structures shall be truly established and maintained by the
contractor, so that the completed work shall conform in dimen-
sions and position to the plans. In order to attain a smooth
and satisfactory finish of all concrete surfaces exposed to view,
the forms shall be plastered to a perfectly smooth finish with
rock plaster, stucco, or other plastering material that will ad-
here to the forms. Before the concrete is deposited against the
forms the plastered surfaces shall be coated with a soap sizing
sufficient to prevent the plaster from sticking to the concrete.
No plaster need be used whenever the width and length of
one planed board or plank of well-seasoned timber will cover
the whole surface of any plane, but no board marks or stains
caused by wood acid or other imperfections will be allowed.

Workmanship. All copings, moldings, scroll work and ex-
posed faces of the concrete work must conform to the lines on

316 HANDBOOK FOR CEMENT USERS.

the drawings. No patching or plastering will be permitted,
and work showing defects after the casing has been removed
must be replaced by new and perfect work.

The entire work must be built by expert workmen ; no exper-
imenting will be allowed. The contractor must satisfy the
engineer as to the experience of the workmen in charge, and
their ability to do first-class work.

Cement. The cement shall be equal to the best American
Portland, the brand to be approved by the engineer. Speci-
mens prepared for a mixture of one (1) part cement and three
(3) parts clean washed sand shall after seven days develop
a tensile strength of not less than 150 pounds per square inch,
nor less than 220 pounds per square inch after 28 days. All
cement shall be kept housed and dry until wanted in the work.

Immediately after being awarded the contract, the contrac-
tor for the super-structure must confer with the contractor for
the sub-structure, and they shall agree upon the same brand
of cement for both super-structure and sub-structure.

FINISHING CONCRETE SURFACES.

The following suggestions regarding specifications for finish-
ing concrete surfaces and constructing ornamental concrete
bridge work are made by W. J. Douglas, of Washington, D. C.,
in Engineering News:

The coping should preferably be cast on the ground and set
in place; but if for economical reasons this is not practicable,
it should be cast in place in alternate sections of about 4 to
6 ft. I would suggest in this connection that it might be well
to use lime mortar rather than cement in these joints; this
will make the joints of the coping open rather than crack the
coping itself.

In most cases where the sinking of the crown was of any mag-
nitude, this sinking had carried the parapet or balustrade down
with the crown, with the result that from the sidewalk of the
bridge the sinking was much in evidence and very disagreeable
to the eye. In order further to guard against this aesthetic
fault I would suggest that the balustrade or parapet be built
after the arch has been struck.

From a careful inspection of cement balustrades and para-
pets, with some little experience in the execution of such work,
I believe that concrete railings should not be built, because they
will not bear the close inspection, which from their position
they must necessarily receive. In the plans for our Con-
necticut Avenue bridge we have used granite coping and gran-
ite posts rather than use concrete. Even with the greatest
care we have as yet been unable to cast concrete with a cement

SPECIFICATIONS FOR THE USE OF CEMENT. 317

face without having hair cracks appear in the surface. The
hair cracks of course are not serious structurally, but to the
layman, who has a right to criticize the work, they are invaria-
bly objectionable and necessarily reflect on the engineer respon-
sible for the work.

Where the concrete railings or parapets are essential archi-
tecturally or economically, I believe much better results can
be obtained by not facing the concrete with mortar at all where
the design permits such treatment. In this case the work
should be finished either by brushing out the mortar with wire
brushes while the mortar is green, which gives a good rustic
finish, or by tooling.

If a mortar face is desired, I believe that it is essential to
use a coarse sand, low in silt, and a mortar somewhat leaner in
cement than is the custom.,It seems to have been the custom in
the past to use a richer mortar in the balustrades or parapets
than in the facing of the arches and spandrel walls, in conse-
quence of which such balustrades are invariably hair-cracked
while the balance of the bridge is in excellent condition.
(From the best available data I am advised that in some
cases the mortar has been used as rich as 1 :1 ; but I think that
it would be better to use 1 :3 or 1 :4.)

In many cases where the balustrade is hair-cracked and the
balance of the bridge is in first-class shape, I attribute the
hair-cracking largely to the fact that the balustrade has been
finished by floating on a thin skin of mortar in order to get a
better finish. This practice I know from personal experience
to be bad, and where you use exceptionally rich mortar, say
1 :li/2 or 1 :2, it is fatal. I believe the best way to treat the
surface is to tool it after taking off the form, in order to take
off the form marks and to give texture to the structure. This
tooling further carries off the efflorescence which so frequently
works to the face, and this treatment further obscures
the hair cracks if they develop. Mr. Quimby, Engineer of
Bridges of the City of Philadelphia, gets a very nice finish
with an ordinary scrubbing brush. Form marks are objection-
able to the eye, but if economy prevents the tooling or brushing
of the surface, in my judgment it is better to leave them on
rather than attempt to cover them up by floating. In fact for
such work as river piers, which do not have to bear close inspec-
tion, I would recommend leaving the form marks on and be-
lieve that the best result is obtained by simply spading the
concrete and omitting the mortar face. The bridge at Dayton
is an excellent specimen of this class of work.

I believe, though possibly from insufficient data, that con-

318 HANDBOOK FOR CEMENT USERS.

crete which has been mixed wet, commonly called "soup," gives
the best results.

I have for the last year or so been in favor of casting con-
crete blocks, particularly when of ornate design, in sand; but
I do not feel fully convinced that there are advantages other
than economy in casting in sand, if the concrete cast in wood
or iron or plaster is kept wet. In the case of iron or plaster
forms this can not be done except by removing the forms as
soon as set, say fifteen hours, and properly protecting the prod-
uct immediately upon such removal.

It is unfortunately a fact that in nearly all the concrete and
concrete steel bridges which have been built, the profession has
not made sufficient allowance for expansion. In steel bridges
expansion seems to take care of itself, but in concrete and
concrete-steel work it is a matter of vital importance. Errors
in design should be rather on the side of too much probable
expansion rather than too little. The Quarry Road bridge,
which was built in Washington several years ago, is not above
criticism in this respect. The spawling at the joint of the
hand rail and rail base and the coping is sufficient warrant of
the insufficiency of expansion joints. Another point worth
noticing in the Quarry Road bridge is, that the rail itself has a
camber, and a couple of summers ago the rail rose, when the
bridge rose, about y 2 inch (due to expansion) ; but in the winter
when the bridge went back to its normal level the hand rail
stuck fast and pulled away from the balustrade. This indi-
cated two things: one that a camber in the hand rail is not a
good thing to build and if built at all care should be taken to
overcome the trouble due to expansion.

The use of metal pipes for draining the fill above the arch
is bad practice where the soffit of the arch is subject to the in-
spection of the public, on account of the staining by the rust.
Metal trimming of any kind other than bronze should be re-
duced to a minimum for the same reason. The drainage of the
arches of the spandrel walls should be carefully studied, as in
many cases the seepage of the water through the concrete dis-
colors the cement face very much. I believe that one of the
best methods of waterproofing is tarring, and where this is
backed up with four or five inches of puddle clay the walls are
almost certain to be dry. The back fill of a concrete bridge
should never be puddled; as even with the best waterproofing
it is highly probable that the face of the bridge will be dis-
colored by the seepage of the water carrying some silt with it.

The bonding of a thick wall of concrete with a thin one
nearly always causes the thin one to crack and is a point of
decided moment in designing work of concrete. The doweling

SPECIFICATIONS FOR THE USE OF CEMENT. 319

of iron railings into concrete should be avoided if possible,
and where it is not possible the dowels should be small.

Where refuge bays or observation places are made in a con-
crete parapet, expansion joints must be made where the
straight reach of the parapet abuts against the portion which
forms the bay, for the thrust of the straight reach will invar-
iably crack the parapet of the bay.

Asphalt roadways and cement sidewalks should not be
placed on a bridge with an earth fill over the arch for at least
two years after the completion of the fill and consequently the
entire bridge pavement should be placed under a separate con-
tract from the bridge proper. About 33 per cent, of the ma-
sonry bridges inspected have badly cracked pavements, due
to paving before the fill has fully settled.

CONCRETE SLAB CULVERTS AND BRIDGES.

The following directions for making reinforced concrete cul-
verts and bridges in horizontal slab form are issued by the
State Engineer of New York for use in the highways of that
State :

Stone flagging or concrete slabs supported by steel I-beams
or rails should be used in preference to plank for covering cul-
verts having less than eight or ten feet span.

Provide a mixing bed 8 ft. wide and 10 ft. long formed of
smooth boards laid close, or of sheet iron. Never mix mortar
or concrete on the ground. Make an open box 6 ins. deep, 2 to
3 ft. wide and from 3 l / 2 to 4% ft. in length, as the span may re-
quire. Whenever the necessary width of opening exceeds 3 ft.,
I-beams of steel must be used to span it, and these must be
placed 2 to 3 ft. between centres, this distance varying inversely
with the width, and the slabs made to span this distance be-
tween the centers of the beams. Provide expanded metal of
gauge No. 4, formed of steel 3-16-in. thick, 5-16-in. wide, in
meshes 6 ins. wide and 12 ins. long and weighing 1.1 Ibs. per
sq. ft., and costing 5 cts. per pound, and cut into sheets of
sufficient size to nearly cover the proposed slabs, being careful
that the 12-in. mesh crosses the span.

To make the concrete, use one part loose Portland cement,
two and one-half parts sand and five parts broken stone or
gravel not exceeding 1-in. in size, all being measured in loose
bulk. If stone from a crusher is used, screen out the fragments
larger than 1 in., allowing the dust to act instead of one part of
sand. If gravel is to be used and is not clean, it should be
washed in running water until the w r ater runs away clear.
Before using any cement, blend the contents of several bags or
barrels about five so that if one bag or barrel is poor it will

320 HANDBOOK FOR CEMENT USERS.

be mixed with four good ones. Thoroughly mix the blended
cement and the proper amount of sand before wetting; then
add enough water to make a thin mortar which is not thin
enough to run; dampen the broken stone or gravel; and then
spread the proper quantity of the dampened stone or gravel
upon the mixing bed in a 4-in. layer, and cover it with the mor-
tar; mix thoroughly by turning with shovels or working with
hoes until all fragments are coated with mortar. The mass
thus formed should flatten and quake when put in a wheelbar-
row or pail, but should not be fluid. Spread over the bottom
of the box a coat of mortar followed by a coat of fine concrete
making a layer 114 ins. thick after ramming, and upon this
lay the sheet of expanded metal and embed it in the soft con-
crete by ramming, using care that the 12-in. length of the
mesh lies with the length of the span of the slab when it shall
be put on the culvert. Fill the box, working the stone from the
sides with a trowel so that the edges will have a smooth sur-
face; rani thoroughly until no stones or gravel can be seen and
until the wet mortar comes to the top, and also smooth the top
with the trowel. Keep this covered from the sun and wet it
night and morning for a week until hardened, when it can be
easily taken from the box. After it has set for an hour, scratch
the word "Top" in large letters in the soft mortar, so that it
may sure be thus laid in the work, as the slab will have little
strength if laid with the embedded metal up. Do not make
concrete in freezing weather, or else make it where it can be
protected from frost. Such slabs can be made in winter by
making them in a warm place free from frost and storing them
for use until they are set and hard.

The flag-stone or concrete-slab cover can be covered by the
road material, and if the culvert is properly built there will be
no expense for maintenance, as is the case with a plank top.
No culvert should be built less than 2 ft. in width so that it
may easily be kept free from obstructions at all times. The
bottoms of all culverts should be given sufficient fall to send the
water out of them quickly. The bottoms, and spaces three or
four feet wide at the inlets and the outlets, should be paved
to prevent undermining, using flat stones set on edge and close
together with the joints filled with coarse sand or fine gravel, or
using cobbles properly embedded. The side ditches should also
be similarly paved where long grades of 5 per cent, or over
occur.

For culverts or short bridges having a span of .less than 25
feet, it is usually most economical to use steel Fbeams, covered
with flagstones or concrete slabs.

In order to give proper support to the upper or compression

SPECIFICATIONS FOR THE USE OF CEMENT. 321

flanges of the I -beams, each beam should be tied to each adja-
cent beam with %-in. round tie rods spaced not over 5 ft. apart.
The centers of these rods should be 2 l / 2 ins. below the tops of
the beams and the two rods in any line which meet in any beam
should be spaced 2~y 2 ins. between centers.

The concrete slabs should be made with a shoulder %-i n -
high along each edge, with not more than %-in. clearance
against the upper flange of the beam. The boxes in which the
slabs are made should be constructed so as to provide these
shoulders. The slabs, when finished, will be 5% ins. thick at
edges and 6 ins. thick elsewhere.

All I-beams should receive two coats of good paint. The
beams should be carefully cleaned before the paint is applied,
and the paint should be well brushed in.

TABLE SHOWING SIZES AND WEIGHTS OF I-BEAMS TO BE USED FOR VARIOUS

LENGTHS OF SPAN FOR BRIDGES OR CULVERTS, USING

STONE OR CONCRETE SLABS.

Limiting: Lengths of

ill pi i!!j ill li

G^ ^'~ ^-?*I (JH j5 t o~'~' "* a-

ft. ins. ft. ins.

53 9% 0.21 46 36

5 3>i 12 % 0.36 50 40

5 3A 14# 0.50 56 40

6 3 A 12% 0.23 66 50
6 3/ 8 UK 0.35 70 56

6 3 A 17% 0.48 7 '6 60

7 3*i 15 0.25 86 70
7 3K ll l / 2 0.35 90 76

7 3% 20 0.46 96 76
84 18 0.27 11 86

8 4A 20^ 0.36 11 6 90
8 4i 3 e 23 0.45 12 96

8 4# 25 l / 2 0.54 12 6 10

9 4r s B 21 0.29 13 6 11
9 46 25 0141 14 6 11 6
9 4# 30 0.57 15 6 12 6
9 4# 35 0.73 16 6 13 6

10 4H 25 0.31 16 6 13 6

10 4*1' 30 0.46 17 6 14

10 4H 35 0.60 18 6 15

10 5% 40 0.75 19 6 16

12 5 31K 0.35 21 17 6

12 5A 35 0.44 21 6 -18

12 5% 40 0.46 22 6 19

15 5^ 42 0.41 27 6 23

15 5 A 45 0.46 28 6 23 6

15 5# 50 0.56 29 6 24 6

The accompanying table shows the sizes and weights of
I-beams which should be used to insure safety in culverts,
when crossed by a ten-ton road roller. The figures in heavy

322 HANDBOOK FOR CEMENT USERS.

type indicate the economical sizes to use. The lengths given
are the clear spans or distances between the side walls. The
I-beams should be long enough to rest a foot on each wall.
The spaces between and outside of the I-beams on top of the
side walls should be filled with concrete or masonry laid in ce-
ment mortar. If care is taken to fill with mortar the joints
between the flagstones or concrete cover blocks, the I-beams
will last many years longer than they will if the drainage from
the road is allowed to wet and rust them.

REGULATIONS FOR REINFORCED CONCRETE CONSTRUCTION, NEW YORK
BUREAU OF BUILDINGS.

1. The term "concrete-steel" in these regulations shall be
understood to mean an approved concrete mixture reinforced
by steel of any shape, so combined that the steel will take up
the tensional stresses and assist in the resistance to shear.

2. Concrete-steel construction will be approved only for
buildings which are not required to be fireproof by the Building
Code, unless satisfactory fire and water tests shall have been
made under the supervision of this Bureau. Such tests shall
be made in accordance with the regulations fixed by this Bureau
and conducted as nearly as practicable in the same manner as
prescribed for fireproof floor fillings in Section 106 of the Build-
ing Code. Each company offering a system of concrete-steel
construction for fireproof buildings must submit such construc-
tion to a fire and water test.

3. Before permission to erect any concrete-steel structure
is issued, complete drawings and specifications must be filed
with the Superintendent of Buildings, showing all details of
the construction, the size and position of all reinforcing rods,
stirrups, etc., and giving the composition of the concrete.

4. The execution of work shall be confided to workmen who
shall be under the control of a competent foreman or superin-
tendent.

5. The concrete must be mixed in the proportions of one of
cement, two of sand and four of stone or gravel; or the pro-
portions may be such that the resistance of the concrete to
crushing shall not be less than 2,000 pounds per square inch
after hardening for 28 days. The tests to determine this value
must be made under the direction of the Superintendent of
Buildings. The concrete used in concrete-steel construction
must be what is usually known as a wet mixture.

6. Only high-grade Portland cements shall be permitted in
concrete-steel construction. Such cements, when tested neat,
shall, after one day in air, develop a tensile strength of at least
300 pounds per square inch; and after ohe day in air and six
days in water shall develop *a tensile strength of at least 500

SPECIFICATIONS FOR THE USE OF CEMENT.

pounds per square inch; and after one day in air and 27 days
in water shall develop a tensile strength of at least 600 pounds
per square inch. Other tests, as to fineness, constancy of vol-
ume, etc., made in accordance with the standard method pre-
scribed by the American Society of Civil Engineers' Commit-
tee may, from time to time, be prescribed by the Superintendent
of Buildings.

7. The sand to be used must be clean, sharp grit sand, free
from loam or dirt, and shall not be finer than the standard
sample of the Bureau of Buildings.

8. The stone used in the concrete shall be a clean broken trap
rock, or gravel, of a size that will pass through a %-inch ring.
In case it is desired to use any other material or other kind of
stone than that specified, samples of same must first be sub-
mitted to and approved by the Superintendent of Buildings.

9. The steel shall meet the requirements of Section 21 of the
Building Code.

10. Concrete-steel shall be so designed that the stresses in
the concrete and the steel shall not exceed the following limits :
Extreme fibre stress on concrete in compression, 500 pounds
per square inch; shearing stress in concrete, 50 pounds; con-
crete in direct compression, 350 pounds; tensile stress in steel,
16,000 pounds; shearing stress in steel, 10,000 pounds.

11. The adhesion of concrete to steel shall be assumed to be
not greater than the shearing strength of the concrete.

12. The ratio of the moduli of elasticity of concrete and steel
shall be taken as 1 to 12.

13. The following assumption shall guide in the determina-
tion of the bending moments due to the external forces. Beams
and girders shall be considered as simply supported at the ends,
no allowance being made for continuous construction over sup-
ports. Floor plates, when constructed continuous and when
provided with reinforcement at top of plate over the supports,
may be treated as continuous beams, the bending moment for
uniformly distributed loads being taken at not less than W L =
10; the bending moment may be taken at WL=20 in. the case
of square floor plates which are reinforced in both directions
and supported on all sides. The floor plate to the extent of not
more than ten times the width of any beam or girder may be
taken as part of that beam or girder in computing its moment
of resistance.

14. The moment of resistance of any concrete-steel construc-
tion under transverse loads shall be determined by formulae
on the following assumptions :

() The bond between the concrete and steel is sufficient to
make the two materials act together as a homogeneous solid.

324 HANDBOOK FOR CEMENT USERS.

(6) The strain in any fibre is directly proportionate to the
distance of that fibre from the neutral axis.

(c) The modulus of elasticity of the concrete remains con-
stant within the limits of the working stresses fixed in these
regulations.

From these assumptions it follows that the stress in any
fibre is directly proportionate to the distance of that fibre from
the neutral axis.

The tensile strength of the concrete shall not be considered.

15. When the shearing stresses developed in any part of a
concrete-steel construction exceed the safe working strength
of concrete, as fixed in these regulations, a sufficient amount of
steel shall be introduced in such a position that the deficiency
in the resistance to shear is overcome.

16. When the safe limit of adhesion between the concrete
and steel is exceeded, some provision must be made for trans-
mitting the strength of the steel to the concrete.

17. Concrete-steel may be used for columns in which the
ratio of length to least side or diameter does not exceed twelve.
The reinforcing rods must be tied together at intervals of not
more than the least side or diameter of the column.

18. The contractor must be prepared to make load tests on
any portion of a concrete-steel construction, within a reason-
able time after erection, as often as may be required by the
Superintendent of Buildings. The tests must show that the
construction will sustain a load of three times that for which
it is designed without any sign of failure.

Several systems of reinforced concrete construction have been
tested for their fireproof qualities and some of them have been
accepted under Section 2 of the above, as more fully stated in
the section regarding the fireproof qualities of concrete in the
preceding chapter.

A REINFORCED CONCRETE FACTORY FLOOR.

The four-story factory of the Textile Machine Works, Read-
ing, Pa., is about 50 by 200 feet in dimensions, and is built of
reinforced concrete and brick. The floors are of Visintini
beams, which are in form triangular braced lattice girders, 6
inches deep, 12 feet 1 inch long and 12 inches wide. Each beam
is reinforced with three steel trusses, 4.5 inches apart. The
upper horizontal rods of these trusses are *4 inch in diameter,
the lower horizontal rods are % inch and the diagonal members
are bars 1 inch by % inch, with 6 sheet plates 1 inch wide
to help the compression diagonals during handling while green.

SPECIFICATIONS FOR THE USE OF CEMENT. 325

The diagonal bars have holes punched in them through which
the horizontal rods are passed. The beams are molded as fol-
lows in an adjoining building, where they are cured until ready
to set in place in the floors. The bottom plank for the mold has
attached to it triangular castings of the size and form for the
openings in the web of the beam, on which are set hollow cast-
iron cores of length the same as the width of the beam, 12
inches. The walls of the molds are 2-inch planks clamped
together.

After the cast-iron cores are set over the bottom spacers, the
walls of the forms are set up, and the concrete, which is mixed
in a box in a very plastic state, is carried in pails to the forms
and poured into them. At the proper depths the reinforcing
trusses are inserted, whereby the cores act as spacers for the
diagonals, but care must be taken not to have any of the diag-
onal straps come too near to them. After the forms are filled,
they are struck off level and clamped at the middle by an iron
strap fitting into a projecting pin. The beams are then left to
set. Quite a number of forms are on hand, and about a hun-
dred of cores. As they have to be cleaned and greased before
use, the cores are pulled out by a lever device three to four hours
after the forming of the beams. The beams are left in the forms
for two days or more, and can be handled at once by hooks and
triangular wooden bars fitting in the open spaces, the weight
of one of the floor beams being 480 pounds, or about 40 pounds
per square foot. The form boards and cores are then cleaned
and greased, and are ready for fresh beams. The concrete is
made of 1 part Portland cement, iy 2 parts sand and 3 l / 2 parts
broken trap rock, passing 1%-inch ring.

The beams are laid side by side, with ends supported on
large girders of the same design. They are tied together by a
set of 2 by 3 inch strips passed through alternate triangular
spaces in the web and bolted to 2 by 4-inch plank on top of the
beams by bolts passing up between the beams. The space be-
tween the planks is filled with cinder concrete and a maple
floor is laid on top.

CONCRETE WALLS FOR FILTER BEDS.

The New Haven, Conn., Water Company has constructed a
filter plant consisting of four acres of sand filter in twelve

326 HANDBOOK FOR CEMENT USERS.

beds, with operating gallery and clear-water reservoir. The
walls, roof and floor are of concrete construction, the two latter
reinforced with Ransome bars. The following description of
the construction of the walls shows the method of allowing
outlets for water from filled beds into those which are not
filled.

The forms were made of spruce boards planed on the side
next the concrete and were usually taken down at the end of
about twenty-four hours in warm weather, but were left in
place about two days in the colder weather of the late fall.
Concrete work was suspended soon after freezing weather
commenced. Special pains are taken to secure smooth sur-
faces and the efforts in this diretion have been successful. The
2-inch boards for the wall forms are slightly beveled on their
edges, so that they can be driven close together, and the joints
are calked, if necessary, with rags or jute to prevent the leak-
age of \vater and cement while the concrete is being deposited.
The upright timbers are cut to fit the profile of the wall. As
soon as the forms are removed any porous places discovered are
promptly troweled with mortar and the surfaces of the walls
are finished with cement grout rubbed with wooden floats.
New concrete has been covered with burlap kept moist to in-
sure satisfactory setting of the cement.

The walls are built in alternate monolithic sections 20 feet
long of the full height. In the ends of sections which do not
come against previously placed concrete a groove is formed
about 6 inches wide and 6 inches deep. These grooves are
smeared with asphalt pipe paint to prevent the adhesion of the
concrete of the next section, so as to make sure that any crack
caused by shrinkage due to the setting of the cement or changes
of temperature will be formed at these places and will occur
without breaking through the tongue of the next section and
thus making a through passage for water. The thin parts of
walls forming the sides of the grooves and the corresponding
tongues are reinforced with twisted rods. Almost all these
joints in the walls built during the past season have opened
slightly, but during the leakage tests have passed only minute
quanitities of water. None of these joints, however, were made
at corners, but all corners are built monolithic with a portion
of the walls extending in each direction.

The wall forms were at first braced with wooden struts in the
usual way to hold them in place, but they floated up slightly,
opening a crack at the bottom, through which the mortar of the
concrete could escape. To counteract this tendency the form
for each section was weighted with two large boxes filled with

SPECIFICATIONS FOR THE USE OF CEMENT.

327

stone. Then the braces were dispensed with and through bolts
used to hold the sides of the forms against spreading. As an
improvement bolts with short hook sections at each end, which
could be taken out when the forms were removed, were tried.

REINFORCED CONCRETE FILTER ROOF.

Later %-inch bolts made in three pieces united by two square
cast-iron sleeve nuts placed 1% to 2% inches in from the face
of the wall were adopted and are now used. The two short
outer pieces are easily unscrewed and taken out while the con-
crete is green, and the sleeve nuts act as cut-offs to prevent the
water following along the bolt and through the wall. Of
course, the small holes made in the faces of the walls are
promptly filled with mortar.

REINFORCED CONCRETE SEWER.

The following brief description gives the method of con-
structing a reinforced concrete sewer at Harrisburg, Pa. :

After the ditch was excavated to subgrade, the bottom was
shaped to the proper profile and section. A small trench was
then dug in the center, below subgrade, and the underdrain
laid with its top about 3 ins. below the invert concrete. A
wooden templet conforming to the shape of the invert was
then accurately set to grade and line, about 12 ft. beyond the
end of the completed invert, and the intervening section laid
in the following manner : The concrete below the line at which
the expanded metal was to be placed was thrown in and
tamped. The metal, previously bent to the proper shape, was
then placed with its ends extending up on both sides for lap
with the arch metal, and the upper course of concrete placed

328

HANDBOOK FOR CEMENT USERS.

REINFORCED CONCRETE CHIMNEY, 182 FEET HIGH.

thereon. Before ramming it was roughly shaped up by means
of a 14-ft. straight-edge, one end resting on the finished invert

SPECIFICATIONS FOR THE USE OF CEMENT. 329

and the other on the templet. After careful ramming the con-
crete was covered with a ^-in. coat of 1:1 cement mortar,
trued by the straight-edge and troweled smooth. Each 12-ft.
section, as it was completed was tested for grade by the in-
spector.

The arch centers were 2 1 /2x2 1 /2 xl /4-i n - steel angles bent to
the proper shape and spaced 3 ft. 4 in. apart, their ends rest-
ing on wooden wedges placed on the side slopes of the invert.
Two-inch planed pine lagging 10 ft. long w T as laid loose on these
centers and coated with soft soap. The arch metal, previously
bent to shape, was placed over this lagging and held at the
proper distance by blocking with small stones. From the mix-
ing-board the concrete was passed through a chute into a box
supported on the lower bracing, from which it was shoveled
into place. Wet concrete was used and forced through the
metal against the arch center, the outside lagging being built
up of rough lumber by outside ribs of pine. After three days
the wedges were removed from under the steel ribs and the cen-
tering collapsed. The inside and outside were then gone over
carefully and all imperfections in the concrete filled with 1 :1
mortar. The backfill was kept 48 hours behind the arch con-
struction.

REINFORCED CONCRETE CHIMNEY.

The following description of the chimney at the Leiter coal
mines, Zeigler, 111., may serve, except as to form of reinforcing
bars, as an indication of the principles of design and construc-
tion used by several builders of such structures. A chimney
of reinforced concerte 310 feet high is under construction.

The new Leiter coal mines at Zeigler, Franklin County, 111.,
have completed a concrete-steel chimney, 154 feet 10 inches
high, with a uniform inside diameter of 6 feet. The power
house with which this chimney is connected at present con-
tains three Heine safety water-tube boilers of 350 horse-power
each, and supplies power to the mines and electric light to the
town. The foundation of the chimney is carried to a depth of
9 feet 6 inches below the new grade and has a bearing 18 feet
square. The foundation reinforcing consists of four layers of
l^x^x^-inch steel T-bars. Two sets lie diagonally with
respect to the sides of the foundation and at right angles to
each other ; the former are spaced 18 inches apart and the latter
12 inches.

The chimney proper is built up around vertical T-rods
li/ixi/ixi/i-inch in size, the bottom ends of which are turned
outward and fixed between the lavers of the foundation rein-

330 HANDBOOK FOR CEMENT USERS.

forcement bars, to securely anchor the structure. Every 18
inches these vertical rods, which are placed flange out, are
banded outside by a T-ring Ixlxl i/g-inch placed with the flange
inside. The vertical rods are in lengths of 20 to 27 feet break-
ing joints around the chimney and overlapping the ends 30
inches.

For 51 feet from the top of the foundation the chimney is
built as two entirely separate concrete shells. The outer
shell, 6 inches thick, takes the wind pressure, and the inner
shell, 4 inches thick, allows for expansion changes with the
high temperature of the flue. At the top of the inner shell 2V 2
inches is left for expansion vertically before contracting the
outer shell to the 6-foot diameter. With a thickness of 5 inches
this forms the single shell of the chimney from that point to
the top. Between the two shells is left an air space of 4 inches,
and about every 18 inches within this air space are blocks, the
size of a half brick, projecting from the outer shell to within
!/2 inch of the inner, to guard against excessive relative dis-
placement. At the bottom of the air space are four openings,
each 4x4 inches in size, for allowing a circulation of air, which
is quite free to pass into the body of the stack at the expansion
joint above, the arrangement tending to keep the soot from
settling into the air space.

The concreting forms consisted of two rings of six sections
3 feet wide, and fastened together with iron latches. These
molds are held only by friction on the concrete and are discon-
nected before hauling to the next course. The flat top ring
is a patent guide ring to hold the vertical steel rods in align-
ment through holes in it. This ring is made of two %-inch
layers of wood and is pushed on up ahead of the concreting.
It also carries the beam for the hoist-pulley. All material is
hoisted inside the chimney.

The sand is Mississippi river sand, and the proportions are
1 cement to 3 sand where high compression exists, and 1 :4 to-
ward the top. The mixing was done with shovels on a plat-
form, turned four to five times dry and at least three times
wet. The concrete was mixed almost dry in very small quan-
tities, and used immediately after mixing and tamped very
hard. The outside finish is a wash of neat cement applied
after the completion of the construction proper. The total
weight of the chimney is 556,000 pounds.

REINFORCED CONCRETE STANDPIPE.

A reinforced concrete standpipe w r ith surrounding tower also
of reinforced concrete was built on the reservation at Ft. Re-
vere, Hull, Mass., in June, 1903, and has given entire satisfac-

SPECIFICATIONS FOR THE USE OF CEMENT. 331

tion. The following is taken from a description of the struc-
ture by Leonard S. Doten :

The tower is octagonal in form, 33 ft. across the base and
and 84 ft. high to the apex of the pyramidal roof. It consists
principally of reinforced concrete, but the deeply recessed pan-
els on the sides are of buff pressed brick. The winding stairs
extending to the observatory above the stand-pipe are also of
reinforced concrete. The roof is of wood, covered with slate.
The foundation course is of 1 :3 :5 Portland cement concrete,
extending only below frost, since it is founded on the "hard-
pan" or glacial drift. A part of the concrete foundation is
occupied by a valve chamber 5x9 ft. in plan and 6 ft. high. The
walls of the tower are 4 ft. thick at the base, with vertical
faces to a height of 4 ft., above which the outer faces batter to
a thickness of 2 ft. at 11 ft. above the floor, where there is a
belt course 2 ft. thick. The external faces of these lower walls
are divided by deep grooves into rectangles, giving the appear-
ance of coursed masonry. The concrete in this part of the
tower is reinforced by ^-in. steel rods. Eight reinforced con-
crete columns, 38 ft. in height, rest on these base walls and
carry a coping upon which the concrete floor of the observatory
rests. The spaces between the columns are filled with the
brick panels previously mentioned.

The stand-pipe, which is the most interesting portion of this
structure, is 20 ft. in diameter and 50 ft. high, containing about
118,000 gallons. The walls are of concrete, 6*4 ins. thick at
the base and 3*4 ins. at top, strengthened by steel rods em-
bedded in the concrete. On the inside there are three coats
of Portland cement plaster, having a total thickness of 1 in.
The concrete was mixed in 1:2:4 proportions. The steel rods
forming the horizontal reinforcement are %-in. in diameter at
the base, with two rings in each horizontal plane, the vertical
distance between the rings being 1% ins. At the top there is
but one ring in a plane and the vertical spacing is 1V<2 ins.
The reinforcement of the body of the tank is completed by
5-16-in. vertical rods wired to the rings at points of contact,
and spaced 8 ins. apart. In the bottom are two systems of
l /4-in. rods crossing at right angles, spaced 4 ins. apart. The
junction between the bottom and the sides is strengthened by
%-in. rods, 3 ft. 4 ins. long, placed radially, about 8 ins. apart.
The cost of the tower and stand-pipe complete was about
112,000.

Reinforced concrete is used for light houses, piles, a hot well,
the Harvard Stadium, wharf construction and many other pe-

332 HANDBOOK FOR CEMENT USERS.

culiar constructions in addition to those named in this and the
preceding chapter.

PORTLAND CEMENT FOR WALL PLASTER.

In an article which appeared in Municipal Engineering Mag-
zine, Mr. F. P. Van Hook presents the following methods of
preparing wall plaster using Portland cement :

Portland cement mortar should be made as follows: Take
good double strength lime, and slake in plenty of water, the
water being put in the box first, 100 gallons of water to 200
Ibs. (1 barrel) of lime. Do not stir the lime only enough to
keep the large lumps from burning. It makes strong lime
granulous to stir while slaking. It should stand a week or
ten days before using. Put in 2y 2 bushels of good, clean hair
to two barrels of lime. When ready to commence plastering,
take one barrel of a good standard brand of American Port-
land cement to three barrels of lime. First mix the Port-
land cement with four parts of sand, mixing the sand and
cement until they are thoroughly incorporated, turning over
at least three times. Second, the lime mortar should be sanded
to the right consistency to make a good, rich mortar. Third,
mix the sanded cement with the lime mortar as it is used.
It will take very little mixing to make a fine, tough mortar.

The "grounds"* to receive Portland cement mortar, fixing
its thickness on the wall, should be % f an i nc ^ f or lath work ;
for brick work or tile, y 2 inch. The proper way to apply the
mortar is to do "drawed" work that is to run on a light coat
first, then cover immediately with enough mortar to fill the
grounds full, finishing same as lime mortar.

A good flat finish can be made by mixing Portland cement
in lime putty, same as plaster of paris finish. For a granulated
finish, screen the sand so it will be clean and uniform (white
sand is the best), mix 1 part Portland cement, 1 part good
lime putty, and add this to 6 or 7 parts sand. This is an ex-
cellent finish for public buildings where water colors are to be
used.

Another very good way for mixing Portland cement mor-
tar is to take 12 cubic feet of putty, sand to the right con-
sistency for good mortar, then as it is used put 4 cubic feet,
or 1 barrel, of Portland cement into the lime mortar, thor-
oughly incorporating it, as it goes to the workmen ready to
put on. This Portland cement mortar makes a wall imper-

* "Grounds" are strips nailed at the end of lath and extending above the thickness de-
sired for the coat, making: a straight edge for the mortar.

SPECIFICATIONS FOR THE USE OF CEMENT. 333

vious to germs, and is especially adapted for hospitals, schools
and where sanitary conditions are of most importance.

CEMENT STUCCO FOR WALLS.

First coat, one-half inch thick.

For best results, the wall should be furred off with spruce
lath put on vertically, 12 inches apart and well nailed.

On these fasten firmly expanded metal lath.

Add fibre to the mortar for lathwork.

Wet thoroughly the surface to be plastered.

Mix 1 part non-staining Portland cement with 2 parts me-
dium sand, 1 part fine sand and one-half part lime flour.
When this coat has set hard, wet the surface thoroughly and
apply the second coat (one-quarter inch thick) with a wooden
float.

Mix 1 part cement as above, 1 part fine sand and 2 parts me-
dium sand or crushed granite.

Before the second coat has set hard, it may be jointed to pre-
sent the appearance of stonework.

A small addition of lime flour increases the adhesion of the
mortar.

The finished surface should be protected for at least two
weeks with canvas curtains or bagging saturated with water.

Defects are liable to appear on cement plastered walls when
(1) to much cement is used; (2) not supplied with sufficient
moisture; (3) not troweled sufficiently; (4) not protected
from variations in temperature and drafts of air.

Plastering work should be done in the spring and never dur-
ing freezing weather.

PLASTERING CISTERNS.

For plastering cisterns one part Portland cement to two
parts sand will make a job that will be impervious to water,
resist frost, and if well done, last for generations.

In cistern and cellar work, if there is any tendency of water
to come in while the cement work is being done, that tendency
must be removed by drainage or otherwise, as the water will
press the cement aside before it is hard.

WATER-TIGHT CEMENT MORTAR.

By the use of lime putty, cement mortar is made more thor-
oughly water-proof, due to the great density of the mortar ob-
tained, which hardens in the water, provided the water is not
moving and not too cold or impregnated with acids.

334 HANDBOOK FOR CEMENT USERS.

The following proportions are best for water-tight mortar:

Cement. Lime Putty. Sand.

1 part y* part 1 part

1 part 1 part 3 parts

1 part 1% parts 5 parts

1 part 2 parts 6 parts

In making cement lime mortar, it is best to thoroughly mix
the sand and cement dry, then screen the lime putty, mixed
with water, into a mortar box and mix whole, adding more
water if necessary till a uniform mortar of proper consistency
is obtained.

The coating may be about % inch thick.

MORTAR FOR BRICK AND STONE LAYING.

For common mortar that will harden quickly, reach greater
strength at less cost than any other cement mortar, Portland
cement should be used with slaked lime in the proportions
given below.

The addition of slaked lime in small proportions makes the
mortar "fat/ 7 "rich" and pleasant to work.

It greatly increases its adhesiveness and density, and con-
trary to general belief, also adds to the strength of such mix-
tures.

Any greater or any less proportion of lime to the mixtures
given, will lessen the density, the tensile strength, the crush-
ing strength and the adhesiveness.

The proper proportions are as follows :

Portland Cement. Sand. Lime Paste

1 part 5 parts ^ part

1 part 6 parts 1 part

1 part 8 parts IK parts

1 part 10 parts 2 parts

This lime paste or slaked lime is more than half water.
Soak the brick well before laying them in cement or the ce-
ment will have no water to make it harden.

DATA FOR ESTIMATES OF CEMENT WORK.

Experience of engineers and the comparison of various ta-
bles of amount and cost of materials required for various
classes of work in which cement is an ingredient demonstrate
that there are no exact rules by which the quantities required
for a given work under a given specification can be definitely
computed. It is easy to determine theoretically the amount
of cement required for a mass of concrete, given the number of
cubic yards to be filled, the percentage of voids in stone and
sand, and the proportions of cement, sand and stone. The ac-
tual result may vary materially either in excess or deficiency
from this theoretical quantity for many such reasons as the
following:

The condition of the stone when voids are determined may
vary as to moisture and compactness, the method and force
used in consolidating the stone and its previous exposure to
rain or sun not being uniform. The same may be true of the
sand. The measurement of cement in original package or after
emptying into a box will make some difference. The method
of mixing materials is an important consideration, in general
the more thorough the mixture the less the volume of the re-
sulting concrete. The method of putting in place and the
amount of tamping are also very important factors. The pro-
portion of mortar to the voids in the stone is not an exact
measure of the resulting volume. The most thorough work
shows a shrinkage in volume of concrete from the volume of
broken stone, unless the mortar is more than enough to fill the
voids in the compacted stone. The same is true to some extent
of gravel.

The following estimates of quantities are therefore simply
approximate and may be exceeded or not attained, according
to the local circumstances. While most of them are the results
of actual experiment under practical conditions, the writer
has checked but few of them in his practice, and presents them
as being correct under a single set of conditions only, and ap-
proximately so in others. For rough estimates they will answer

336 HANDBOOK FOR CEMENT USERS.

satisfactorily. Each engineer or contractor is soon able to
estimate his own quantities under the conditions of the
methods he adopts better than he can from any statements of
average results.

PACKING AND SHIPPING CEMENT.

Cement is packed in barrels, cloth sacks or paper bags, as
ordered.

A barrel of Portland cement weights about 400 pounds gross,
and should contain 380 pounds net of cement.

Portland cement, loose, weighs 70 to 90 pounds per cubic
foot; packed, about 110 pounds per cubic foot.

A barrel of eastern natural hydraulic cement weighs about
320 pounds gross and should contain 300 pounds net of cement.

A barrel of western natural hydraulic cement weighs about
285 pounds gross and should contain 265 pounds net of cement.

Natural hydraulic cement, loose, weighs about 50 to 57
pounds per cubic foot ; packed, about 80 pounds per cubic foot.
Weights of cement and volumes of barrels are not uniform.
Nearly all natural hydraulic cement is sold in sacks.

Slag cement weighs about 350 pounds gross, or 330 pounds
net.

Cloth sacks ordinarily contain one- third of a barrel of nat-
ural hydraulic cement. The standard for Portland cement is
one-fourth of a barrel. Paper sacks contain one-fourth of a
barrel.

The following on cement packages is from a circular issued
by a firm of general agents for cement :

Four paper bags or four cloth bags constitute one barrel or
380 pounds of Portland cement. The paper bags are charged
to the customer at 2% cents each or 10 cents ber barrel, and are
of no further value. They have served their purpose in carry-
ing the cement to destination and have given you service that is
worth 10 cents per barrel. The cloth bags are charged at 10
cents each or 40 cents per barrel, and are worth 10 cents each
or 40 cents per barrel if returned and received, freight paid, in
good condition at the mill.

Here has been the misleading part to the consumer. While
a few paper bags are liable to be broken in transportation
with a corresponding loss of cement, the minimum loss of ce-
ment in a cloth bag is one pound to the sack or four pounds to
the barrel. This amount remains unshaken from the bag. We
have seen laborers so careless as to waste 3 per cent, of their
cement in this manner. A paper bag is more easily handled
can be emptied with absolutely no loss of cement. It takes time

DATA FOR ESTIMATES OF CEMENT WORK. 337

to untie a cloth bag and time costs money. A paper bag can
be cut open with a hoe instantly.

The manufacturers and the railroads require bags returned
to be freight prepaid. The minimum expense of such transpor-
tation from this district is 1*4 cent per barrel, which you pay.
Use paper and save it.

The following table from Engineering News gives some idea
of the variation in size of cement barrels. The first three
brands named are American and the other two foreign Port-
land cements :

(1) (2) (3) Difference Difference

Portland Capacity Actual Volume between between

cement of bbl. contents when (1) (2)

brand. cubic packed dumped and and

feet. measure. loose- (2) (3)

Giant 3.5 3.35 4.17 4% 25%

Atlas 3.45 3.21 3.75 4" 18"

Saviors 3.25 3.15 4.05 3" 30"

Alsen 3.22 3.16 4.19 2" 33"

Dyckerhoff 3.12 3.03 4.00 3" 33"

A carload of Portland cement usually means 100 barrels
(40,000 pounds) ; 75 barrels is the minimum carload, or the
same quantity by weight in cloth or paper bags.

When cement is ordered in cloth sacks the sacks are charged
at cost, viz: 10 cents each, in addition to the cost of the ce-
ment; but when the sacks are returned to the works in good
condition, freight prepaid, 10 cents is allowed for each, with a
deduction of 2 cents for wear and tear in some cases.

For paper bags there is no charge, as they are not apt to be
returned.

Empty sacks to be returned should be safely tied in bundles
of ten or fifty giving the name of the sender.

WEIGHTS AND MEASURES OF CONCRETE MATERIALS.

Sand weighs from 80 to 100 pounds per cubic foot dry and
loose; from 90 to 115 pounds dry and well shaken.

Gravel weighs from 100 to 120 pounds per cubic foot loose
and about 20 pounds more when well rammed.

Crushed limestone weighs about 90 pounds per cubic foot,
varying somewhat either way with the size and amount of fine
dust.

Copper slag, which has been used successfully where weight
is wanted in concrete, weighs 120 to 125 pounds per cubic foot.

Concrete weighs about 140 pounds per cubic foot.

Quicklime weighs 64 pounds per cubic foot.

The weight of cinder concrete, composed of 1 part cement,
2!/2 of sand and 5% of screened cinders, tamped on a wood
center, will average ninety-five pounds per cubic foot. Eighty

HANDBOOK FOR CEMENT USERS.

pounds per cubic foot is often given as the weight of cinder
concrete, and this is probably about right where the concrete
is not tamped ; but for all concrete tamped on wood centering,
ninety-five pounds per cubic foot should be used in computing
the weight of the floor and the strength of the steel beam.

Lime mortar and ordinary concrete will average 120 pounds
per cubic foot.

Lime paste, about 50 per cent, water, one cubic foot of quick-
lime and one cubic foot of water, make 1% to l 1 /^ cubic feet of
stiff lime paste.

Lime requires about 50 per cent, of its weight in water in
slaking; natural hydraulic cement requires 28 to 31 per cent;
silica-Portland cement, 22 per cent; Portland cement, 20 to 25
per cent. ; slag cement, 22 to 28 per cent. ; cement and sand mor-
tars, 10 to 23 per cent, to complete the process of crystalliza-
tion.

To make one cubic yard of Portland cement mortar the fol-
lowing quantities of cement and sand are required for the pro-
portions stated, the cement being given in barrels, packed, and
the sand in cubic yards :

Barrels of Cu. Yds.

Proportions. Portland Cement. of Sand.

Neat cement 7.14

1 cement 1 sand .. 4.16 0.67

..2.85 0.84

..2.00 0.94

..1.70 0.98

..1.25 0.99

..1.18 1.00

The following table shows the variations in amount of ingre-
dients necessary to make a cubic yard of concrete. The table
appears in the report of a committee on the use of cement made
to the Association of Railway Superintendents of Bridges and
Buildings and is made up from reports of such superintendents
for various railways, giving their actual practice and observa-
tion:

DATA FOR ESTIMATES OF CEMENT WORK.

339

PROPORTIONS.

AMOUNT OP INGREDIENTS.

Natural
Cement.

Crushed
Stone.

Rubble

Natural m
Cement "

Portland
Cement

w o

Gravel

1
1

IVa
2
2
2
1

2
2
2

2*
.3

3
3
3

4
4
4M> or 5
5 or 6 and
2

4
5 or 6 and
6
6
4

6
6%
7%
7H

Bbls.

1.5
1 9

Bbls.

Cu.Yds.
0.35

Cu.Yds.
0.95

Cu. Yds

1.5
1.0

1
1
1
1
1
1

1
1

1 or 2 sere

eningrs.

1 00

3
11.5
jl.4
(16
il.O
I 1.2
1

0.39
0.45

0.42
0.35

0.79
0.96

0.83
0.95

3
1 or 2 sere

eningrs.

1.0

1.00
1.00

0.92

]!:?

ll.2
0.96
ll.2
11.0
1 1.2
0.82
0.96
0.9
0.68

0.36
0.51

0.5

0.5
0.55
0.37
0.43
0.35
0.35

1.00
0.87

0.9

1.00
1.00
0.72
0.94
0.85
0.96

.25

The following table of approximate quantities of materials
to make 100 cubic feet of finished concrete shows the reduc-
tion in amount of cement used if the ingredients are meas-
ured in the mixing box rather than in .the original package :

Proportions of Cement
to Aggregate.

Barrels of Cement
When Proportioned
by Barrels.

Barrels of Cement
When Proportioned
by Measurements.

Yards of
Agrgregrate.

1 to 1

18.3

15.8

2.75

1 2

11.6

10.

3.85

1 3

8.7

7.5

3.95

1 4

6.9

5.9

4.15

1 5

5.6

4.7

4.30

1 6

5.0

4.3

4.40

1 7

4.4

8.7

4.45

1 8

3.9

3.3

4.46

1 9

3.4

2.9

4.47

1 10

3.0

2.6

4.48

1 11

2.8

2.4

450

1 li

2.5

2.2

4.53

1 13

2.4

2.0

4.*5

1 14

1.9

4.57

1 IB

2.2

1.8

4.59

1 16

2.1

1.7

4.62

1 17

2.0

1.6

4.63

1 18

1.9

1 5

4.65

1 19

1.8

1.4

4.68

1 20

1.7

1.3

4.70

340 HANDBOOK FOR CEMENT USERS.

This table is given in the California Portland Cement Com-
pany's handbook.

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