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, 2 JBLIC R
A JOURNAL OF HIGHWAY RESEARCH _
UNITED STATES DEPARTMENT OF AGRICULTURE
BUREAU OF PUBLIC ROADS
MKS
= ARS we, 8 f. . a
s < - : y ,
4 . ees y
; 4 Ks
THE CONNECTICUT AVENUE EXPERIMENTAL ROAD
U.S. GOVERNMENT PRINTING OFFICE: 1928
PUBLIC ROADS
A JOURNAL OF HIGHWAY RESEARCH
U. 8S. DEPARTMENT OF AGRICULTURE
BUREAU OF PUBLIC ROADS
CERTIFICATE: By direction of the Secretary of Agriculture, the matter contained herein is published as administrative information and is required
for the proper transaction of the public business
The reports of research published in this magazine are necessarily qualified by the conditions of the tests from which the data are
obtained. Whenever it is deemed possible to do so, generalizations are drawn from the results of the tests; and, unless this is done,
the conclusions formulated must be considered as specifically pertinent only to the described conditions
R. E. ROYALL, Editor
VA CEO Rs MAY, 1928
TABLE OF CONTENTS
Page
49
Report on Connecticut Avenue Experimental Road
A Cantilever Testing Apparatus for Mortar Beams. ; . ; 70
Gasoline Taxes, 1927 ; , 72
THE U. S. BUREAU OF PUBLIC ROADS
Willard Building, Washington, D. C.
REGIONAL HEADQUARTERS
Mark Sheldon Building, San Francisco, Calif.
DISTRICT OFFICES
DISTRICT No. 1, Oregon, Washington, and Montana. DISTRICT No. 8, Louisiana, Alabama, Georgia, Florida, Mississippi,
Box 3900, Portland, Oreg. South Carolina, and Tennessee.
DISTRICT No. 2, California, Arizona, and Nevada. Box J, Montgomery, Ala.
Mark Sheldon Building, San Francisco, Calif.
DISTRIC TanosaColoradainey Mereomnd Weemice DISTRICT No. 9, Connecticut, Maine, Massachusetts, New Hamp-
shire, New Jersey, New York, Rhode Island, and Vermont.
301 Customhouse Building, Denver, Colo. Federal Building. T
DISTRICT No.4, Minnesota, North Dakota, South Dakota, and eceheh UU CuNe wa TON ate
Wisconsin. 410 Hamm Building, St. Paul, Minn. chee yee ee ae North Carolina, Ohio, Penn-
: 2 ’ ’ i e
DISTRICT No. 5, Iowa, Kansas, Missouri, and Nebraska. Willard Building, Washington, D. C.
8th Floor, Saunders-Kennedy Bldg., Omaha, Nebr.
DISTRICT No. 6, Arkansas, Oklahoma, and Texas. DISTRICT No. 11, Alaska.
1912 F.& M. Bank Building, Fort Worth, Tex. Goldstein Building, Juneau, Alaska.
DISTRICT No. 7, Illinois, Indiana, Kentucky, and Michigan. DISTRICT No. 12, Idaho and Utah.
South Chicago Post Office Building, Chicago, III. Fred J. Kiesel Building, Ogden, Utah
ee EE EEE
Owing to the necessarily limited edition of this publication it will be impossible to distribute it free to any persons or
institutions other than State and county officials actually engaged in planning or constructing public highways, instructors
in highway engineering, periodicals upon an exchange basis, and Members of both Houses of Congress. At the present
time names can be added to the free list only as vacancies occur. Others desiring to obtain Pustic Roaps can do so
by sending 10 cents for a single number or $] per year to the Superintendent of Documents, U.S. Government Printing
Office, Washington, D. C.
REPORT ON ie eS EXPERIMENTAL
A DISCUSSION OF CONSTRUCTION AND MAINTENANCE METHODS AND PRESENT CONDITION OF
VARIOUS TYPES OF SURFACE LAID IN 1911, 1912, AND 1913
By the Division of Tests, United States Bureau of Public Roads
ing from Chevy Chase Circle to Chevy Chase Lake
in Montgomery County, Md., was constructed as
two separate projects by the Bureau of Public Roads
during the years 1911, 1912, and 1913. These two
projects included a number of different types of con-
struction which have since been subjected to a very
heavy traffic and which have been maintained by the
bureau. The behavior of each section has been closely
observed and the cost of maintenance carefully re-
corded. This report summarizes the methods of con-
struction employed on the 16 experimental sections,!
their present condition, and the yearly cost of pre-
serving their surfaces in serviceable condition.
The dividing line between the two groups of experi-
ments is at Bradley Lane (fig. 1), the sections lying south of
this intersecting road having been constructed as water-
bound macadam with subsequent bituminous surface
treatments or as bituminous macadam. The experi-
ments north of Bradley Lane are characterized by use
of Portland cement concrete as a wearing surface and as
a foundation for bituminous and vitrified brick surfaces.
Figure 1 shows the location, grade, and nature of
the experimental sections. As indicated, a double-
track street railway divides the thoroughfare. At the
time of construction the east side of Connecticut
Avenue was not improved north of Bradley Lane,
consequently the north experimental sections were
subjected to traffic traveling in both directions, whereas,
those lying south of Bradley Lane have carried only
one-way traffic. In 1924, with the extension of the
pavement on the east side from Bradley Lane to Wood-
bine Street, experiments 1, 2, and most of 3 of the north
eroup were relieved of the northbound traffic. How-
ever, the remainder of experiment 3 and all of experi-
ments 4, 5, and 6 still carry traffic in both directions.
Traffic counts were made periodically from the time
of construction up to the end of 1921 on the sections
south of Bradley Lane and up to the end of 1922 on
the sections north of Bradley Lane. Observers were
on duty for the full 24 hours of each thirteenth day,
thus obtaining 28 counts, one of which was made on
each day of the week four times during the year.
From these data the average number of vehicles per
day was obtained. Traffic counts were made again in
1927 and showed a tremendous increase in traffic over
all the sections. This was found to be true also of
those sections between Bradley Lane and Woodbine
Street, in spite of the fact that they have been relieved
of the northbound traffic.
The car-track area occupying the center of the street
has never been paved with an impervious surface and
has provided a means for water to gain entrance to
the subgrade. Surface drainage afforded by the narrow
cobble gutters on the sections south of Bradley Lane
has not been entirely satisfactory. Automobiles fre-
a Bas Connecticut Avenue experimental road extend-
1 Reports describing the construction and behavior of these experiments are in-
cluded in Circulars 98 and 99, Office of Public Roads, U. 8. Department of Agricul-
ture Bulletins 105, 257, 407, and 586 and U. S. Department of Agriculture Circular 77.
101304—28——1
% 2
4
‘a babe 5%
9; ee ee Seg Page
k
a
ey
-
STEPS IN CONSTRUCTION AND FINISHED PAVEMENT OF PENE-
TRATION MAcADAM, EXPERIMENT 3
quently park with their wheels in the gutter and in
some places the gutters are no longer at grade. The
street is narrow for the traffic which it carries and
without adequate side support for the road. Conse-
quently the edges of the bituminous-treated surfaces
present a rather ragged appearance.
49
50
BITUMINOUS MACADAM EXPERIMENTS DESCRIBED
The first experiments constructed on Connecticut
Avenue were seven bituminous macadam sections of
the penetration type built in 1911. Table 1 shows the
extent of these sections and the nature of the bitumi-
nous materials entering into their construction. The
characteristics of the bituminous materials, as indicated
by laboratory tests, are shown in Table 2; and the
quantity of application at the time of construction and
in subsequent retreatments is shown in Table 3.
In preparation for the bituminous wearing course,
the existing waterbound macadam was scarified, re-
shaped, and sufficient crushed limestone added to give
a compacted foundation course 514 inches thick. The
improved roadway was approximately 19 feet wide.
Originally the 2-foot strips adjacent to the street-car
rails were left as waterbound macadam. About two
PUBLIC
years later those were scarified and treated with bitu-
minous material by the street railway company, and
subsequent surface treatments by the bureau flowed
over them. A cobblestone gutter was constructed at
the outer edge of the new pavement and, as required,
French drains 214 feet deep were installed under the
cutters and next to the tracks, and some herringbone
drains were laid under experiment 6.
The work was done in the fall of the year and condi-
tions were unfavorable for bituminous construction.
Much of the penetration work was done when the
average air temperature was 45° to 50° F. In virtu-
ally all cases the stone chips and screenings were dried
and heated before they were used. All of the bitu-
minous binders were distributed by means of hand
pouring cans, except on experiments 1 and 2, where
the hand-operated pressure-nozzle method was used.
<i e z y © &
» st nN? Pa res }
wo
a/ 3
o 3B “
Zs tu j= iw = li + Cue
“BITUMINOUS ele Gi ts 7 S| {2 ZS} |] fw
O MACADAM >| lz fe ce a «|| «| |>™ =| [>a ‘> =
| 1° o & 6 bh E] [zs e| [¥> Kia $
= GB} joo 2| [bo SS
wr fat lu
%, MODIFIED
De COAL TAR | BITUMINOUS | BitumINOUS MACADAM, | BITUMINOUS MACADAM, | © OMINOUS | BITUMINONS
OS Prine MACADAM, J MACADAM MACADAM
4NL, COAL TAR FLUXED NATIVE ASPHALT | GILSONITE OIL ASPHALT , ,
x REFINED OlL ASPHALT OIL ASPHALT
CHEVY CHASE CIRCLE DOUBLE CAR TRACKS OF STREET RAILWAY
SURFACE SURFACE SURFACE TREATMENT, BITUMINOUS | | BITUMINOUS BITUMINOUS
BITUMINOUS} TREATMENT, | TREATMENT, :
SEE IDUAL UT ASPHATHIC. Loe relay WATER GAS TAR MACADAM, || MACADAM, MACADAM
\ ’
< EMULSION | cecoon ene. | PETROLEUM PREPARATION OIL ASPHALT | OIL ASPHALT | OIL ASPHALT
> © 4 a = >
x 2 x S S|) 2 Ie a} |G | S|} |S | ot tt Wy
Pe a = = =} |x ro) | =| |= =) ie a
eo & = = =) (5 Se l rae al |b &
S$ <= fo) j a. ys “” ao
& as |
lbh 10 : 9 .: 8 5 6
© - on 3 a: 3S @
ar tt SF oS & on
2.00 "a
SpER CENT “oT lieveL -0.72 PER CENT , 1.67 PER CENT
* tics 8
N o + és
EXPERIMENTS SOUTH OF BRADLEY LANE
30+20
61+80
wn a e = 2
o : 3 = = iS
vis a L—+— 5 6
tJ = ao
» tu a> S w] [2 ne!
a ef fs S}) | |3& bs a] erga fs lel |b = 9] |< =
= as} [se = >= tus Bl jew a} fu |e x =<} |= <x
bm cx Se x x =| la 1G o a} |=
ar Sf fr = Qe = Clie F&F wie |Z < ei I= =
= 9 i oD A pe te bd a) Gi is =
SECA | sec.B | seca ! secs SECA ; — SEC.B J SEC.C |SECA) SEC.B | SECC | ceo SEC.B he con Paice
BITUMINOUS CONCRETE] BITUMINOUS CONCRETE CEMENT CONCRETE OIL CEMENT CON. JOIL-CEM.| Cement | concrete | CEM Iconc|CEMENT pa Ned es &
hese veel Peers kepaataell heen SURFACE TREATED WITHIBITUMINOUS MATERIALS. | CONC. ] CON. {UME tconcRETEFOONCRETEL ty t 1 EET T tI!
l GRAVEL! LIMESTONE ! GRAVEL [LSTONE! GRAVEL |GrAveL| GRAVEL | LIMESTONE |) } TRAP AIBC 101 E [FIG HIT YIKILIMINN |,
5 la
DOUBLE CAR TRACKS OF STREET RAILWAY <
1 t =
>
=
END OF PAVEMENT NO THOROUGHFARE *
f+ concre re PAVEMENT CONSTRUCTED IN 1924 ns
lu aan)
= S ile slit wall Sli Silsic
<f > wy tr Z = = = = s 2
z < x=] jw =<] Ih & ra) = So
a 7 2 = = =
= —_
- LEVEL |
~0.35 PER CENT ~20 PER CENT — 1,50 PER CENT —5.00 PER CENT LEVEL
= ty o95 PER CENT
Qo
cam ]
wo
-
m~
~N
58+50
6i+80
Q
wo
+
oa
T+
EXPERIMENTS NORTH OF BRADLEY LANE
Fig. 1.—LocaATION OF VARIOUS EXPERIMENTAL SECTIONS.
Tur GRADES ARE APPROXIMATELY THE SAME ON Bota SIDES
OF THE TRACKS AND THOSE DESCENDING TOWARD THE NORTH ARE SHOWN AS NEGATIVE
May, 1928
PUBLIC ROADS 51
Ps Beek ge ' . ies : ae
RDM a Bears " rene J 3 " ee he ee a Pee
EXPERIMENT-2
EXPERIMENT-S
CONDITION OF SURFACE-TREATED
In some cases the construction procedure was varied
slightly as will be noted from the following descriptions
of the several sections:
- jExpervment No. 1.—The wearing course consisted of
limestone, graded in size from 3 inches to 1 inch, laid
to a dep th of 3 inches loose measurement, and rolled
lightly. Heated coal tar was then applied at the rate
of 1.8 lane per square yard, covered with screenings
(three-fourths-inch to dust). and thoroughly rolled.
After the excess screenings had been swept from the
surface, a seal coat of tar was applied at the rate of 0.8
gallon per square yard, covered with screenings and the
road completed by rolling.
The seal coat of this section wore off rather rapidly
and was replaced by an application of crude coal tar in
EXPERIMENT-6
SECTIONS IN 1928
1914. Following this treatment no more than normal
wear took place. Some waviness developed adjacent
to the gutter and occasional patching was required,
but in general the appearance remained that of a uni-
form, well-bonded mosaic surface. In 1918 this sec-
tion was given a surface treatment of 0.19 gallon of re-
fined coal tar with a covering of 14-inch stone chips.
A similar treatment consisting of 0.337 gallon of refined
coal tar and sand was applied in 1924. This is the
only section of this group of experiments which has
required a surface treatment since 1918.
As this section is located on a curve, the more severe
scouring action of traffic is probably the cause of the
need for the additional maintenance treatment. At the
present time this later treatment has worn off in the
o2
PUBLIC
Vol. 9, No. 3
traveled area and some pitting and wear of the coarse
stone is noticeable. ;
Experiment No. 2.—This section was constructed as a
modification of the Gladwell method. A 1-inch cushion
of sand was spread evenly over the foundation and
given an application of 1.18 gallons per square yard of
light refined coal tar. After the tar had been absorbed
by the sand a layer of limestone (3 inches to 1 inch)
was spread to a depth of 3 inches and thoroughly rolled.
The surface was completed as in the case of experiment
No. 1, using 1.95 gallons and 1.02 gallons per square
yard of heavy refined coal tar for the penetration and
seal applications, respectively.
The surface showed a tendency to bleed and the non-
uniform application of chips made to correct this con-
dition resulted in some surface irregularities. The
surface was resealed in 1918, but no general treatment
has been applied since that time. Next to the car
tracks the unprotected edge has been broken by traffic
and presents a ragged appearance. Some pitting of
the aggregate has occurred, but the surface in general
is in very good condition.
Experiment No. 3.—This section differed somewhat
from experiment No. 1 in details of construction.
Limestone from 2 inches to 1 inch was used in the sur-
face course and was thoroughly compacted before the
bitumen was poured. Clean chips, three-fourths to
one-fourth inch in size were used both after the pene-
tration and seal-coat applications. The initial pouring
of fluxed native asphalt was at the rate of 1.46 gallons
per square yard. One-half gallon per square yard was
used for the seal coat. A shortage of material neces-
sitated using a refined semiasphaltic oil on a small area.
During the early period of its life, this experiment
developed the appearance of a sheet-asphalt pavement.
Later, as the seal coat wore uniformly, as mosaic sur-
face was presented. It was conspicuous for its uniform
cross section and it is still the smoothest of the bitumi-
nous macadam sections. <A seal-coat treatment of
refined asphaltic petroleum and 1%-inch stone chips
was applied in 1918. Throughout its life maintenance
costs on this section have been lower than on any other
section of this series.
Experiment No. 4.—This section was constructed of
2-inch to l-inch limestone, spread to a depth of 3
inches and lightly rolled. The first application of
asphalt was at the rate of 1.65 gallons per square yard,
and the second at the rate of 0.55 gallon per square
yard. A light covering of stone chips was spread after
the first application while after the second application,
screenings from three-fourths inch to dust were used
on a part of this section and clean chips on the remain-
der. The surface was completed by rolling with a
3-ton roller.
This section lies at a low point in the grade and drains
experiments 3, 5, and 6 on the west side. The placing
of the asphalt binder course was completed late in the
evening, and rolling and pouring of the seal coat was
TABLE 1.—Cost and description of experiments on Connecticut Avenue, Chevy Chase, Md.
BITUMINOUS MACADAM (PENETRATION) EXPERIMENTS, SOUTH OF BRADLEY LANE, BUILT IN 1911
| * :
| | Original construction Annual cost of surface ae See ha maintenance in cents per
@ —
a 5. 1912 1913 1914 1915 1916
Tos) = “ _
2 4 = iS 3 Q © 2 © 2)
2 eae ae Ble | & z H
SS ae at Bituminous material or type £3 | se = 3 a es = a = a =| a
= > ag D a D = 2 a © q © =|
5 ra a “st 3 Ss e g 2 = 2 S & = 8
Aan ee: Be | S |e24i's |] 8) 3 )8 )3 145 724 oi
i S = ic ° m . Ea = pa S a S a ba
S ny | 6 | oO Ba! oe ae Pee a ee) ee ee ee
| | Square
| Feet | yards Cents
PTR UBS bd, B81 Tl Cal tar, Tempe sos ec oneness eee eee 260 4? BO 9S ToS ee es okt at 5. Od oO. 74 1 Se Died taceees 0. 28
a eet “Ole 105.) (Coal tar, refined. (modified). 1.4... bes oneeatbecscneascus Ret & 26.) Bh de ie, 2) wreck nuke del oee Met looonm bcs paiiemeee 2.293 ae oe . 64
Boze est ) S25 || 1, O8h)| Pinxed native agnialls 7. oie coe uetoa eek eee eee eae ee 1.062). OS: GO Mo AL cclena Shale ore en Ee tea cece ln ee aieaere <O6 aes | .38
$e) 9823 || 2,568 | Of asphalt (Giisonite) =. seen cae ees ee eee ee BAe, BLAS eee {ear > Bel RARE see C20 Bence 2.) See 2.09 Nace . 67
Tie ee 810°) 2,447 || Of asphalt ve. 242502) ee cb ces oe ee Nees eeoncer ote DeLee Hesoane 17.08. Wewows , 00 loan ce » OB Re anal 208 locaste i 6 53
Geena Ae6 1 a BRR" (OD asplall, Ss eee eye Soe eee ee ee rre cee Seni 2.09 1 63.22 |nc..8 eae ae Ap og een ee ce of BOF. at ae . 57
TA aunt) 9 449 130) OF] Basalt se ne os cee Site ee ee 2: 26. 1) 50. 96. 12.2... LN PE el eee be ee Jew. ee 7 ee \ 29
i Ee 60) 849) Of atphalt.oc. coe cen cals ewe a rene ae ean ew ene 1,86 | 64.80 | 8.01 |------+-|------|------|------ Si Paven en FBO to lace .
SURFACE TREATMENT EXPERIMENTS ON WATERBOUND MACADAM, SOUTH OF BRADLEY LANE, BUILT IN 1911
| |
fae | 7821 L477 | Water-tas tay praparaiion-y. eee core oe ee eee 0. 54 | 2 39. 59 | pre | ere a CE ee (Bn ee | Jaume | 3.40 | 6.55 | a7
Be wt 403 46.1 Aspliaitic petroleaits | sc yen eee: Seas ee ee ee ie Pat oo aa BABE ee aon, 4.7 1.18 | 7.50 | .88| 8 76| 1.48
1) ¢ See 482) LOS | Besidusl petroleum 8 oe ee ee ae ewe ee ee ee SCs REDD hee De tae Heese 1.88 | 8.11 | 20.17 | 7.80 | 5.24 | 8.90 | 4. 08
pees: 201 | '377 | Native asphalt emulsion........-..----------------------------- 339) | HOLDS Ho git kos eae clea meee aw —- een sae | 1.56
’ i} | |
EXPERIMENTS NORTH OF BRADLEY LANE, BUILT IN 1912
1 Pca a, | 635 | 1,498 | Bituminous concrete (Topeka specification) 2 inches thick on |
Bm 2 827 Gemment vonereies sce oe ea oe eee Se oe by es Ce SN PE. 8) A ee ee O22 SexansicLeteeee
cae | 630) 1,400 | Bituminous concrete (District of Columbia specifications) 2 |
| | ' inches thick, on 6-inch 1: 3:7 cement concrete and seal coat
Of O.41 galion fluxed native mepliali 2. on. ce omece eee ulseeeee 590: BO i 2, Se OS ee Ae ee A: Ae ee ee ee 0. 25
= 5 1,840 | 4,178 | Cement and oil-cement concrete as in experiment No. 2, surface |
'- treated with various types of bituminous materials___._._.___.!-_-__- (7: eee Ore oe Aes Soe fee 5 OS a hcrnaalersesh | .06 | 7.81 . 29
ee ee 771 | 1,744 Oil-cement concrete, 1:134:3 and 5 pints residual petroleum
per Dag af cament..«<.ce5icl ee at oe dee Co eb at eee cee eee ts es eee | See ak Ee ec, Ss | Ord dt Medes 1 HS ee 1. 02
ee 1. Bed 1 Bs) Goethent concrete, 2 PIES Be onnterere Deets vee es eee ee Lace 14%) St |. cs: ealadee bale os tas lea OT Pos A) ee . 28
Rinseridcens 980 | 2,055 Vitrified brick, with base as in experiment Nos. 1 and 2, 2-inch | |
| sand cushion grouted with 1 : 1 sand-cement_______.________-- he ee PE ST = a | A ae See | TP CP oe 8 » OB ee OF t58 co Ge
| |
1 Some of the sections were of varying widths.
2 Includes cost of wearing course.
Mary, 1928
postponed. That night there was an extremely heavy
rain, and water drained from experiments 3, 5, and 6
came up through the stone of experiment 4, so that it
was necessary to tear out the cobble gutter at a number
of places to drain the subgrade. About a week later
an effort to resume work on the section was discon-
tinued because the subgrade was still wet and soft,
and it was not until some time later that the laying
of the surface could be completed.
This surface gave early evidence of requiring repairs,
but bleeding, which began with the advent of warm
weather, caused the surface to seal itself. Some depres-
sions occurred along the west edge and waviness and
lack of stability in the surface were more apparent on
that portion on which screenings containing dust were
used in covering the original seal coat. In 1918 a sur-
face treatment was applied consisting of 0.305 gallon
per square yard of oil asphalt and a %-inch stone cover.
At the present time the section is in good condition, but
in general the surface has worn more unevenly and has
developed more waviness than that of experiment 3.
Experiment No. 5.—This is a divided section located
on both sides of the car tracks. The stone of the wear-
ing course, which was the same as that used in experi-
ment 3, was thoroughly compacted before the applica-
tion of the binder. The first application consisted of
oil asphalt applied hot at the rate of 1.69 gallons per
square yard. Chips from three-fourths to one-half
inch in size were then spread sparingly and the surface
PUBLIC
ROADS
thoroughly rolled. The second application consisted
of 0.56 gallon per square yard of the same material and a
covering of stone three-fourths to one-fourth inch. The
surface was then rolled until firm and smooth.
During the first few years after construction this
section required considerable maintenance due to unsat-
isfactory subgrade conditions. Weak places as they
appeared were dug out and patched. With the gradual
elimination of these weak places the condition of the
section has been materially improved and the cost of
maintenance decreased. In 1918 a light surface treat-
ment consisting of 0.227 gallon per square yard of hot
asphalt and %-inch stone was applied. The surface at
the present time is unbroken and in good condition
except for some waviness.
Experiment No. 6-—This section also is located on
both the east and west sides of the car tracks. The
Wearing course consisted of 3-inch to 1-inch limestone
spread to a loose depth of 34%inches. After a thorough
rolling, the first application of asphalt was made at the
rate of 1.56 gallons per square yard. ‘This was covered
with clean stone chips, three-fourths to one-half inch in
size, the excess of which was swept off after rolling.
The second application of 0.53 gallon per square yard
of a harder grade of the same material was then made,
covered with stone chips, and rolled.
Herringbone drains were laid on the west side of this
section. Their installation, however, was apparently
not entirely effective. Subgrade conditions were simi-
TABLE 1.—Cost and description of experiments on Connecticut Avenue, Chevy Chase, Md.—Continued
BITUMINOUS MACADAM (PENETRATION) EXPERIMENTS, SOUTH OF BRADLEY LANE, BUILT IN 1911
io)
Annual cost of surface treatments and maintenance in cents per square yard a
| | a ee
1917 | 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 35
S a — ——- - — as
| @ © 2 mo | | @ | © >) ro) fi. 8 2 2 S|
— | oO i) Q S | o az i oQ } 2 oO © 2 © rhe
3 ae ie: s])/9ais8i1 4 | al & a | @ ie} | FB tl ae | ube a | a 2 | as
g o is en) qi So i a i) a | ee ST o | A Di ait © | ) a) q ro) r= eg
a g = g q§ | 2 = 2 rei;}S hth 2 12 x | 2 S| g SI ol B 2 = 2 aS
3 Pea See oe eel ha | es Meee |B Pe? Siig et Sl Be epg 7s
2 eerie Wasi es eh ee ee at ep) a eT Sp eS 2 SP Soe abe ze
a Pas) a Poe ete] eB Lae fa Pe Pap ey spe oe] Beles | Oe a ae eee Be,
“4 | net ; a a —— aye
| | | | Cents
| per
} i | } ] sq. yd.
| 7 | Si) 1282 pe GeV eee 0.72| 43.01
‘ee ee Le IB Pe ye CA ee eR to PO Pete bE Weacrcanl eect Brece lee erie OCW a Art aed el | 1
ee eaten 2e8t | 2e.42))) 2984. ae. RENE ee ae Sees Se EEC EERE FS ee CE eeoeres Pee ee ae te Oe RS (RRS ma Cee ene . 89 33. 37
i Oe PER Pea Ska ed acel ca ccattane came ewtierefetiec or HEY Re Ee Ceres Somes ee Ty) 2 a SE a ac Mean .65| 29.18
ee 8) SES EDT S (Cie CORR RS nee TERE Desa FEA i: | RU ORE 3 ROA Wee Dewees 08 Seen 2 ae 2.51" et | 3.29} 43.05
ee en e70 | NGOS, (2.75 bcs oc Ti Ot eas Oa eet ieee Iie ES PEA AS oad ee ee eto 5 TY ieee Sasa | 56.59
rae Cee ZT Be keer ATS? 7p Lace ROR eRe eats, eae DE Nea eral eat Rec: ce sg Bel aacens SS aaa Gh as aad
Bt — Peet Jes) eee ee ett etons ee fests es dece ee gen aS RO eet WEE. Pn | A Cg eae | 3.36] 57.76
| | j . ee
SURFACE TREATMENT EXPERIMENTS ON WATERBOUND MACADAM, SOUTH OF BRADLEY LANE, BUILT IN 1911
: | | |
| | 57 | | 55 | 5.79 | 11.41 | 11.94 | | 0.33 | 85.48
tin & 69 | 0/37 |-.--.-- Geet E She RMh o Ne een Ne eee Reece 0.05 | eee ees cone G21 1 0/55)) 2.62 |... .79 | 11.41 | 11.94 |... | 0.33 | 48
Behan | 593 | .71 | 11.50) 3.43 | 11.36 |1.08 || 8.18 |.--..- 17.21 | 4,23 |... Nene kee FD Ve macinel BR TO Parra ee AT Laecearod PBB RT ene | 85 | 163. 75
BY fteeretcrncs 5.36 | 1.39] 9.11 | 2.04 | 10.49} .81| 6.89) 2.27 | 17.54 1.06 |... cea AREA ARE WL Secs BB eed BTA ead | BL. 86 tac] 2.33 | 155.35
(Ta RE ee 1.35 | 12.80 | 6.89 J----=--|------ PAOD iS Tlie nyc (8.44 |----- eae hu 92 | 268 | 708 | B76 |e e | 6.63 ------| 9.18 |-----. 1.32 | 79.22
Fe ee ee ee ee ar eesrsueameen aimaneaannn nanan REA
EXPERIMENTS NORTH OF BRADLEY LANE, BUILT IN 1912
a OT il ee LDN ee de a ge ee
| | | |
1 TE rae eee feet ae (6 Benmen a eae Eee i Oh bc ceuens R87 les. (eR | eee Ry seers | one I Bos 5 Rea 1.18/ 9,54
7“ pueeies | alls i : |
! | | i { }
2 | | 30 AE eee! 06 (bee AT cae | .79 — PRA C aeen LOH cmd AGN we 1.86} 10.25
o> an Cn ian: ead air 1, ee ee | 7
fee | ees | 0.04 |..----- Ci OT ce. OU eed i3 bea | .16 | 10.45 | 1.38 |---| 3.52 |_-...-| Wy eee +) a oe | 253) 87.79
ir 7 | | | | | i a Soe | 4.86 | 47.40
WS aoe £29 Wosbee gh sem MOG. Scores | 1.93 | 10.46 | 3.31 }.--.-- Ty eae 4.99 |....-- te ne oe 11. 9 | 4.86] 47.4
eee peat ETD isa a oo) eee fe BR Were ca de | 122 | 10.45 | 1.69 |--._-- 3.49 |_-__. A ESA Me ces . } ee ra | 1.07 | 22.7
| | | i afte | By | ' | 6 C
hee | ai we | Lo & peer | 00 — 66 | ec | -66 |... | 08 es 8 | Aeon id coe pease |---=-- 28 |------ 4.42 |._.... | 1.69 9. 26
OR aR a a ling eT ER RR | SY | ee Se a ee ee eee ee
PUBLIC ROADS
Vol. 9, No. 3
Hanvp PouRING THE SEAL COAT ON ONE OF THE PENETRA-
TION MACADAM SECTIONS
lar to those of the adjoining experiment 5, necessitatin’
similar maintenance treatment. ‘The extensive early
repairs gradually eliminated the weak places and, as in
experiment 5, lowered the maintenance costs during
later years. The north end of this section on the west
side is so located that it was subjected to much more
traffic up to the year 1924 than the other sections.
The highway up to that time was not improved be-
yond Bradley Lane on the east side, and north and
west-bound traffic therefore crossed the tracks at this
point to remain on pavement. During 1918 it was
deemed desirable to smooth and seal the surface by
adding a surface treatment of 0.293 gallon per square
yard of hot asphalt and one-half inch stone. The east
side of the experiment has continued generally better
than the west side. Its present condition is similar to
that of experiment 5.
Experiment No. 7.—This experiment was located en-
tirely on the east side of the car tracks and comprises
two tests designated as sections A and B. Section A
was constructed with two applications of bitumen as
in the other bituminous macadams of this group, but
in section B the second treatment was omitted. The
asphalt used was of a considerably harder grade than
that used in other experiments.
ADAM SECTION
TABLE 2.—Analyses of bituminous materials used in original construction of the experiments south of Bradley Lane
POCINERE TU DOr..: on Soe Leak isaeces week land 2 2 3 4 5 6 3 8 9 10 10 | ll
ent Refined .,| Residual | Asphaltic
Coa] tar | Fluxed | Gilsonite . : Asphaltic . Native
Material et are refined | native oi ek It Rett aA. aia petro- ae 4 Ree asphaltic .
(light) asphalt | asphalt PLE Pp Pp ete leum ! 1912 1914 emulsion
Specs sravity-25°/25" C onc scesacecstanceuc 1, 258 1, 219 1. 058 0. 974 0. 999 0. 989 0. 973 dis 0. 949 0. 976 0, 964 1. 038
Specific viscosity, Engler:
SE 7 dl Oe Ct 0 re, en MT ee ae aS ee en ee, (me ae eee Os see Rll ee A eee ee 1ST once a coe Olea
O BOF Oi, BO Qin cces ec lies e SeB illest apc b lees Phot zocee cece aes sere nO et oe ee ee re ee Te Ne Sie Says Ae . saip erica
“ell CA 1; ne clk Lo) en Oe wa ee ee ae Sed) me eee SP ee yt Tis 2. slaw ee 118.3. {case
Float test: |
Ts, DO Os BOON. eas eee 01 ere aa eee | ee ae oe eee ee! Ch ee me eee ee Sep BS
ey OR" C),. GOCOTOS., Soo wee wide COL lee eee ere Yh Se ee ee ees Ce ey ee Se ee ee ak Berl a) Bewe e Vs, ee ee oe br soins eee
Eg CTR nts Dc) le 6 a 2 nn eS Pe ee hee eee, Pe yet ee ae RE eh Ee coe ee eee £6 i eee
be yot gy siiey di oft) bth ea, 0 neh oe iA Sei TOA we Mae ets Sy Ra See I NR ea Pi Se Sen eh Sea i ee ee BE Liveenn seen
EW Lape) dele) 6 ila! bb oe a ee eo Sy Ol ue ey A Sew fp 46 52 7 47 OO oo. Sel dckn cose dalle ee eceewkanek Sap es
Panstration, 25° C., 100 f., 6 Second$. ooeec ois cans wee eee ne 128 146 73 94 68 cc cont adlleeecaccustlowaws eens h peewee lice hacer
re oent tors, ha? O., Sy a0 woe ce aoe alent eek occ 2.14 0. 87 0. 05 0. 68 hy Ee Re ee eek 27.10 «18. } 26. 46 8 3.35
ree Cant loss, 106" 6.5 Sire. 20 oo coc wtien op tad ohm wl Paualwacwetalletue.. cecal lta bates fale cence ad eee eee eee 16; 7 Ue atd erase eee §2. 54
PP MTIGTS CLAS OLN TOSEOTIOL. cade 0 nre aut SoM ec ere a ee oe 456 5 99 6 65 479 1) ees } Meee Se ak EO Nec Se a ce 8195
Frioat test on residue, 50" 0; -aecomis.. oc. vcteaw deed caslbs leceucedl cuae eee che tek wecec lence oben eee eee enna eee eee $100 | casas oe 81 v7
Fidat test on residid, 82° 0, seconds... «ceeet ahiuccedadenlud clunker Ghetckaaculk dtco re ote ee ee ae ee ee eee 8 32 229 AAO Nias tea
rer centage soluble i O84... vscusce tee ated lw ete eeseeceee 94, 51 99. 81 99. 46 99. 59 ty ees 99. 88 99. 74 | 99. 92 36. 30
Percebtage organic insoluble. -.cc<5 2. cen fee ee nobcuele andicecie 1. 00 0.12 0. 50 0. 28 ae al 0. 08 0. 23 | 0. 06 1.10
Fercentage inorganic insoluble s ... <a acenl-asacesacnleke dans ar 4.49 0. 07 0. 04 0.13 0. O82 eon kee 0. 04 0.03 | 0. 02 3. 30
Bitumen insoluble in 86° B. naphtha__.-..__|_........-|_....--_-- 20. 78 21.13 24. 68 20. 10 SAO Le eae 9. 10 9. 93 4. 43: | eee ee
Dees CREDO TION OOD Es 55. eh dorian Stace wanton a cee ctica aaa eee 10. 64 7.79 13. 53 8. 36 iL) boy ee eat. 4,91 7. 67 DOL Laivcnstca
POG CATON: DBE CONG. x oenkxncontdiatucenceenn 29. 60 26 SOr esd ap boleh wreck ci ene ae 8. OA) Wate. ag casket eatedenahee 49. 50
na | Ammonia... ..-...--s------s-- 35
Distillation, percentage by weight: Fatty and resin acids._.-._-.- 9. 45
et, a he EP Ee, es eee | 0 LE ey nN MP aie AE Fg a mS Re wien Week fm ath 0
RITE TAY Ral Clit et cess ct one ee Loe ae eS 10,2 ay G | Ree rene ie me Mek eb oe Ce es Pe 0
P1006 S709 Oicascec eta. see ote 10.6 Bay? et, Ae Se a ee ee ee | en ee ee 16
ETO Sis Bite Lice eee oo ee ek eee 1210, 2 Lt eee er ee SP Rhy Less 9 A I, See ee De” a 11 24.8
Oe Sey Bae Raa See oe eo 107, 5 ts Pay) Re ee ee ee NPE ete Se ey 19,7
POOH E i catieddn. Poehce tobe ieee beds | 16 81.4 Li, yt one eee ee, we ee! Se et «ee ere 17 64.9
gE er 99.9 ee ie eee Se ed! a a eG Ms 8 Ae 100. 0
1 Fairly thin fluid with strong naphtha odor. 10 Solid.
? Viscous, sticky fluid. 1 Clear.
? Loss in addition to loss at 105° C.
4 Sticky, glossy surface.
§ Mottled surface.
§ Sticky, slightly mottled surface.
’ Hard, fairly lustrous.
* Residue from percentage loss test at 105° C.
§ Residue from percentage loss test at 163° C.
2 Turbid.
13 One-third solid.
4 Two-thirds solid.
18 One-sixth solid.
16 Hard, dull, brittle.
17 Sticky, semisolid. A 350-375°
dimethy. sulphate.
C. fraction showed 7.5 per cent insoluble in
May, 1928
PUBLIC ROADS
ay)
Stone ranging in size from 21% inches to 1 inch was
spread to an uncompacted depth of 31% inches. The
first application of bitumen was made at the rate of
1.66 gallons per square yard for the two-coat test and
was followed by 0.6 gallon per square yard, chips being
spread sparingly following each application.
In the case of the single-application experiment
stone chips 1 inch to one-half inch were spread over
the coarser stone layer after it had been thoroughly
compacted. The hot oil asphalt was then applied at
the rate of 1.86 gallons per square yard, covered with
chips, and rolled. |
Within a year after construction the binder appeared
to be lifeless. It was considered also that the asphalt
used was too hard and had a melting point too high
for this type of construction. A number of worn
depressions occurred in both sections A and B, although
to a much greater extent in the single-application area.
These defects were repaired and a surface treatment of
0.29 gallon of cold asphaltic oil and one-half inch stone
was applied to the patches on section A and to the
whole of section B. This treatment undoubtedly
saved section B from total failure.
From 1912 on, with the exception of the year 1915,
this section required only light repairs up to 1918 at
which time it received a surface treatment of 0.29
gallon of hot asphalt and 1%-inch stone.
Subsequently section A required considerable patch-
ing and section B developed many short irregular waves.
These waves have not, however, developed serious
roughness although considerable cracking has occurred
on a 3-foot strip adjacent to the car tracks. At the
present time the appearance and condition of this sec-
tion compares favorably with the other experiments of
this group, although the maintenance costs for the past
few years have been somewhat higher than the average.
BITUMINOUS MACADAM IN GOOD CONDITION AFTER 16 YEARS
Approximately 16 years have elapsed since these ex-
periments were constructed. During this period they
have carried very severe traffic and in their broken
edges and repaired local failures they show the effect
of the stresses to which they have been subjected.
Nevertheless, all are still in serviceable condition and,
with continued careful maintenance, should not require
reconstruction for some years to come.
TABLE 3.—Gallons of material per square yard and type of material used in the construction and retreatment of the experiments south of
Bradley Lane
Exper- Year
iment 7
No. 1911 | 1912 1913 1914 1915 1916 1917 | 1918
_| : | _ a: 2)
a ORSON. 2.09 .-- ---<enessncmmma CN 0.316 coal tar, xX sn | 0.190 coal tar, re-
coal tar, refined. | | crude.! fined.?
J [eas See ee MS eh Se. Se ee ape SO Lek LL. ees. . - See oees Glenn e ' 0.255 coal tar, re-
coal tar, refined. fined.2
Xe eee a see ee oe 2S os ee eee man ccs ce eee tec asa le le nee See eee 5 SIO - on SEB Sw ' 0.299 residual as-
fluxed native as- | phaltic petrole-
phalt. | | um.2
- Sena ae Consrragmoneo:20 !...........---...... Pe ee ed dT get OO js Pe et 0.305 residual as-
Gilsonite oil as- | phalitic petro-
phalt. | | leum.3
essen cee Se ERI Eo ee, 5 5 en ec Pr eee 3. | 0.227 residual as-
oil asphalt. phaltic petro-
| leam.? ©
Oienceee a et |e oe ee ee os ow oi | + 2 ee eee be ee |e ese as ee ue. 2d 0.293 residual as-
oil asphalt. phaltic petro-
' Jeum.?
(ees Construction, 2.26 | ee ee ee IR ee ee ek. ~ pe a ee |. es, . ees ' 0.290 residual as-
and 1.86 oil as- phaltic petro- phaltic petro-
Phalt. | _leum.? | ' Jeum.?
So tee | Sos Construction) 540i) 0.250 watenmpasiiaae|. see... see. --.- | . cee 0.149 water-gas tar, | 0.156 water-gas tar, |........__-------.--
water-gas tar refined.! preparation. preparation.
preparation.
eee a kee Construction,0.530 | 0.204 asphaltic pe- | 0.209 asphaltic pe- | 0.197 asphaltic pe- | 0.289 asphaltic pe- | 0.213 asphaltic pe- , 0.204 asphaltic pe-
asphalt petro- troleum.$ troleum.$ troleum.$ troleum,$ troleum.é ' troleum.é
leum.
U2 ok | ee Constriceen,0.790))..........--....-... Reconstruction | 0.172 asphaltic pe- | 0.299 asphaltic pe- | 0.172 asphaltic pe- _ 0.178 asphaltic pe-
residual petro- 0.476 asphalt pe- troleum.5 troleum.° troleum.é troleum.$
leum. troleum.§
os ee Osea Rp | i a eS ae ae 0.225 asphaltic pe-
native asphalt , troleum.$
emulsion. |
Year
Exper-
iment - EES Say . . S ee a —
No. 1919 1920 1921 1922 1923 1924 1925 : 1926
| ine |
nn MN egy ee, eee ee (ee ne eet COMmmUaT, (FO Bete en oo cae ce soe Selene eee eee ses
| fined.3
, ae ee eee | eee EE | 8 Eee ee
ee = em a a ee ee ew = a aia wae ee ee won ew ee eee we
| 2 eee ee coe ee NCEP) UN en gn ae | DE ne ee es! 5 ee SS) Pena ee a Oe
- J ee conc A a SS ee ee en eee
(3 eee : Deal eg = oe = oa “Agggll apee e a eeene So aan lL. ee a
= "0.339 water-gas tar |.._____._.--- | ~~ se § ae. eee 0.348 coal tar prep- ee ee 0.406 coal tar prep-
preparation.’ aration.3 aration.
om... - 0.140 asphaltie pe- | 0.118 asphaltic pe- | 0.453 asphaltic pe- |_....._.._....------|--------------------|-------------------- eee ee Oe anes oe Sr
troleum.§ troleum.§ troleum.5 — :
— 0.140 asphaltic pe- | 0.069 asphaltic pe- | 0.449 asphaltic pe- |......-..-----------|--------------------|-------------------- pees meee era Se eee
troleum.5 troleum.$ troleum.$ | |
ee ee. ee ee ne a ee 0:132g6 phodiMGibes: |- .2eue-2sseenesesee D teierriitaenceaiacieraaiiee
troleum.$ troleum.? | |
1 34-inch gravel cover material.
2 14-inch stone cover material.
3 Sand cover material. ;
41-inch screenings cover material.
§ Torpedo sand cover material.
PUBLIC
ROADS Vol. 9, No. 3
CONSTRUCTION OF SURFACE-TREATED SECTIONS DESCRIBED
Late in the year 1911 an 8-inch limestone water-
bound macadam road was constructed for a distance of
approximately 1,700 feet on the east side of Connecticut
Avenue, beginning at the District line at Chevy Chase
Circle. Cobblestone gutters were constructed along
the east edge and drainage installations made as re-
quired. After being exposed to traffic for several
months this highway was divided into sections for sur-
face treatment with bituminous materials. These ex-
periments are listedin Table 1. Laboratory tests of the
bituminous materials used in the original applications
are shown in Table 2.
eae ee ORES et. TS BR AE AI RSS AES
= oe
he
: :
cet e:. 7 eS ¢ ie. :
; é P aan ee Sa gS sie — ' oe :
oe - a ee i ald . 2S eae auc ‘
x “oe oe Agen ey a i cee ne : —
Sia i a ey
APPLYING BITUMINOUS MATERIAL FOR SURFACE TREATMENT
Exepervment No. §.—Surface treatment was applied
under favorable weather conditions in August, 1912.
The cold water-gas tar preparation was applied by
means of an automobile distributor at the rate of 0.54
‘gallon per square yard after sweeping the bonded
macadam surface. Several hours were allowed for the
tar to penetrate into the road before the cover material
of limestone, 1 inch to one-half inch in size, was spread
at the rate of 1 cubic yard to 72 square yards of surface.
Under traffic the tar mat wore away rapidly, but it
had penetrated well into the macadam surface and
effectively bonded the upper layer of the stone. A year
after construction several holes were patched and the
whole section was given a surface treatment of 0.25
gallon of the same type of tar as used in the original
treatment and a cover of l-inch screenings. In 1915
the surface mat showed some signs of instability. Six
retreatments have been required during the period
between 1912 and 1926, the first four using a water-gas
tar preparation similar to that constituting the original
application. A cold-application coal-tar preparation
was employed in the retreatments of 1924 and 1926.
Torpedo sand was used as the mineral cover in all of the
retreatments except in those of 1913 and 1924 when 1-inch
screenings and sand were used, respectively. In August,
1927, this section presented a smooth fine-textured
surface. In numerous small spots the last application
of tar has picked up, revealing the underlying treat-
ment. Indications of instability were very slight.
This experiment at present is in better condition than
the other surface-treated macadam sections which,
however, have not received retreatments since 1921.
Experiment No. 9.—Surface treatment with cold as-
phaltic petroleum was applied in June, 1912, at the
rate of 0.53 gallon per square yard. The macadam
surface was well swept and application made with a
street sprinkler and covered with 1-inch to Y%-inch
limestone at the rate of 1 cubic yard to 72 square yards
of surface. Several hours elapsed between the distrib-
ution of the oil and the application of the mineral cover.
The oil mat withstood the abrasion of trafic better
than the preceding section treated with tar. How-
ever, a tendency to become muddy in wet weather
was noticeable and deterioration developed in the more
lightly traveled areas of the section.
A very considerable amount of patching has been
required on this experiment and treatments of asphaltic
petroleum were applied annually from the time of
construction until 1921. Retreatments were applied
by pouring the oil on the road surface and obtaining
distribution by hand brooming. Since 1921 main-
tenance has consisted only of patching.
The surface is fairly smooth and intact in the traveled
way, but somewhat more uneven adjacent to the car
track and the gutter. Fully 25 per cent of the south
half of the section has been patched. Fewer patches
have been required on the remainder of the section.
Experrment No. 10.—This section was treated with
a hot residual petroleum apphed under pressure. The
process of application was hampered by the cold weather
of late November and by a small amount of water
contained in the oil. The application of 0.79 gallon
per square yard was immediately covered with stone
chips of the type used on the two preceding sections
but in a somewhat greater amount.
This experiment gave promise of becoming trouble-
some from the beginning. The subgrade was soft and
there was difficulty in bonding the macadam. With
the advent of warm weather the thick mat began to
bleed, necessitating the addition of more stone covering.
It also proved unstable under traffic and developed a
marked degree of waviness. Continued maintenance
; | ry ] sl
j
~
CONDITION OF EXPERIMENT 11 IN FEBRUARY, 1928.
WatTER-BounpD MacapDAM SuRFACE TREATED WITH
ASPHALT EMULSION
failed to correct this condition and in 1914 it was
scarified, brought to grade by the addition of new
stone and refinished as water-bound macadam. After
being opened to traffic for a few days a new bituminous
treatment of asphaltic petroleum was applied. This
material was the same as that applied to the adjacent
experiment, No. 9, in fact, constituted an extension
of the same treatment. Unfortunately, the work of
reconstruction was done late in the fall and numerous
small potholes soon formed. Persistent waviness and
the tendency to become muddy in wet weather were
characteristic of this section during its early life.
Additional treatments of asphaltic petroleum were
applied at the time such work was done on experiment
May, 1928
PUBLIC ROADS il
No. 9 and the two sections have similar records of serv-
ice behavior and cost.
| The surface of this experiment is now in good con-
dition although heavily patched. The accumulation of
material resulting from the several surface treatments
constitutes a rough strip about 3 feet wide adjacent to
the gutter and has pushed over the cobblestone edging
in some places. :
Experiment No. 11.—This section was originally
intended as a part of experiment No. 10 but a shortage
of oil necessitated the installation of an additional sec-
tion which was constructed by a method of grouting.
The existing macadam was scarified and harrowed
and new 21-inch to 1-inch limestone was added to
EXPERIMENT-7
EXPERIMENT-9
CONDITION OF PENETRATION MacabDAM (EXPERIMENT 7)
sive a 3-1Inch layer of loose stone. A mortar prepared
in the proportions of approximatley 4 cubie feet of trap
rock screenings to 101% gallons of native asphalt emul-
sion was mixed in a concrete mixer and spread to a
thickness of 244 inches over the stone. As soon as the
emulsion began to dry out, screenings were scattered
over the surface and a 10-ton roller forced the mortar
into the voids of the loose stone until only a thin layer
remained on the surface. It was intended to apply an
emulsion flush coat in finishing this section, but, owing
to adverse weather conditions, this operation was
postponed until spring.
For five years maintenance on this experiment was
very slight and the first surface treatment was not re-
quired until 1918 when 0.225 gallon per square yard of
asphaltic petroleum with a torpedo-sand cover was
applied. Subsequently, a very considerable amount of
10 1604——28———2
patching has been necessary. This experiment, as in
the case of experiment 1, is located almost entirely on
a curve and consequently is subjected to the same
scouring action of traffic. The condition of the pave-
ment at present is fairly good although there are many
cracks on the inside of the curve near the sidewalk.
MAINTENANCE COSTS MUCH LOWER ON BITUMINOUS MACADAM
SECTIONS THAN ON SURFACE TREATED SECTIONS
Traffie carried by the east and west lanes did not
differ widely up to 1921. Later traffic counts, made
during 1927, show that this relationship still holds.
Subgrade conditions are believed to have been reason-
ably uniform throughout the length of these experiments
EXPERIMENT-IO
AND THREE PENETRATION MACADAM SECTIONS IN 1928
and the maintenance costs on the several sections may
therefore, be regarded as fairly comparable.
As might be expected the cost of maintaming the
bituminous macadam surfaces (shown in Table 1 and
fig. 2), has proved to be far less than the costs on the
three strictly superficial bituminous treatments on
waterbound macadam. For the former the average
yearly maintenance cost for the 16 years since construc-
tion has been 2.60 cents per square yard as compared to
8.30 cents per square yard on experiments Nos. 8, 9, and
10 over a period of 15 years. Experiment No. 8 of the
surface-treated group has proved more economical than
experiments Nos. 9 and 10, but nevertheless its average
annual maintenance costs have been more than double
the average of those on the bituminous macadams.
The bituminous grouted section, No. 11, partakes more
of the nature of the bituminous macadam than of the
08
PUBLIC
ROADS Vol. 9, No. 3
surface treatments. However, as it is not closely
related to any type at present being. constructed,
its costs are omitted from this comparison. Yearly
maintenance costs and traffic on the experiments south
of Bradley Lane are shown graphically in Figure 2.
EXPERIMENTS WITH HIGHER TYPE SURFACES CONSTRUCTED
NORTH OF BRADLEY LANE
The six experimental sections located north of
Bradley Lane constitute a continuation of the work
previously discussed, but are located only on the west
side of Connecticut ‘Avenue, as indicated in Figure 1.
As previously stated, these sections carried traffic
traveling in both directions up to the end of 1924, at
which time that portion on the east side of the car tracks
was paved from Bradley Lane to Woodbine Street
BITUMINOUS MACADAM SECTIONS
I-WAY TRAFFIC
4000
3000
2000
1000
AVERAGE DAILY NUMBER OF VEHICLES
180
140
1eo
i900
80
a
LY
60
Pewee |
SECTION NO.5
pt
\
40
ACCUMULATED MAINTENANCE COSTS-CENTS PER SQUARE YARD
[
ae
ESN
mmm mmm meme eee
SURFACE TREATED SECTIONS
I-WAY TRAFFIC
AAI
Heat HA)
[EZ Lo
ie Prom) Dea
Da) 42)
meee relieving experiments Nos. 1, 2, and most of 3 of
the north-bound ‘traffic. The average ‘daily traffic carried
by these experiments 1s shown graphically i in Figure 2.
Up to 1921 they carried slightly heavier traffic than did
those sections south of Bradley Lane. However, dur-
ing later years the continual development of the adja-
cent territory has greatly increased the traffic on the
latter sections. The traffic counts made in 1927 show
that the sections south of Bradley Lane carried approx-
imately 50 per cent more traffic than did those north of
Bradley Lane.
However, in comparing the effect of the traffic car-
ried by the various experiments consideration should
be given to the higher concentration necessarily ob-
taining on those sections carrying vehicles traveling
in both directions.
EXPERIMENTS NORTH OF BRADLEY LANES
2-WAY TRAFFIC
fall
Y
is el
eee
m ~ nm NN PO w i
Sa A Ga a & ws wow © Swe = @eainant CBR a es Ss
see e28 282 & oo ao 7m oanadgcstrnAan=nNAfM @
= badd $44 Qa — — _ = = — — a —_ = —_
YEARS
Fic. 2.—MAINTENANCE Costs AND TRAFFIC ON EXPERIMENTAL SECTIONS
May, 1928
The construction of these sections was begun Sep-
tember 9, 1912, and continued until December 13,
during which time experiments Nos. 1 and 2 and por-
tions of Nos. 3, 4, and 5 were built. Due to the late-
ness of the season, the construction of the remaining
portions of the latter experiments and all of No. 6
was postponed until the spring of 1913, and the road
was finally completed May 17, 1913. Table 4 shows
the character of the six experiments, and a summary of
their construction details and subsequent service
behavior follows.
TaBLeE 4.—Character and extent of experimental sections con-
structed on Connecticut Avenue north of Bradley Lane
|
Eee Location
=a = - Area Type Aggregate
No. A From—| To—
Square
yards
A 0-15} 3+19 2 inches bituminous concrete | Limestone.!
1 1, 498 (Topeka specification).
B | 3419! 6-+20 ee Trap.
A 6+20 | 9+04 2 inches bituminous concrete | Limestone.'
3 District of Columbia specifica-
a 1, 400 tion)
B 9+-04 | 12+-50 Eee ee ee Trap.!
A 12+50 | 15+84 ‘Cement concrete surface treated | Gravel.
with bituminous material.
B 15+84 | 21+60 RUMUCME eee Sn so Limestone.
3 C 21+60 | 25+03 4.178 ee rere Gravel.
A 25+03 | 27-+29 |(” '}Oil-cement concrete, surface | Limestone.
eee with bituminous mate-
rial,
| B | 27+-29 | 30+90 =e 9 ee eee a a Gravel.
(ae 30+90 | 33+60 '(Oil-cement concrete.__.__....___- Do.
4 | D 42+-50 | 44+-61 fi 74 SOG (See eee DO mes Limestone.
'| B | 46+10 | 49-400 il gM ee Trap
A 33+60 | 37+85 WSmient coberete..........2.....- Gravel
5 | B 37+85 | 42-+-50 3 013 |J----40-------------------+------- Limestone.
C 44+61 46+10 Z Hee OIee eee eae Do.
D | 49+00 | 524-00 ee Otte ee Oe ee Trap.
re §2+-00 | 61+80 | 2,055 | Vitrified brick.......-_._-.-.-.-- See Table 9.
{
1 Aggregate used in the bituminous concrete. Gravel used in the cement concrete
of the base.
Prior to the construction of the experimental sections
the road surface was 8 inches of waterbound limestone
macadam in very bad condition. This old surface was
spiked, plowed, and scarified, and the suitable stone
was reclaimed and used to backfill the trenches of
French drains which were constructed at both sides of
the new pavement. The installation of these drains
was suggested by the character of the subgrade soil,
which is a decomposed mica schist that absorbs water
very readily. The drain along the east side was 3 feet
deep and extended throughout the entire length of all
experiments; that on the west side was laid under the
eutter with the 4-inch tile at a depth of 2 feet below
the subgrade. The latter extended through all sections
except experiment 6, which lies on a fill.
The barrel-shaped concrete gutter which was laid
along the west side of the experiments was built to a
width of 3 feet with a depth of 4 inches at the center.
The base of this gutter was 1:2:4 gravel concrete
laid very dry and the top, immediately applied, was
one-half inch of 1:2 mortar. The entire length of
eutter was laid before any of the pavements were con-
structed, and the concrete surfaces and bases were
struck off with a strike board which rested upon the
cutter. There were no joints in the gutter except the
joints at the ends of day’s work. When the forms
were removed the base was found to be very porous.
PUBLIC ROADS
By the time the concrete pavement sections were
laid against this gutter it had attained considerable
tensile strength, and, in contracting, had cracked at
frequent intervals. When the pavement concrete was
poured against the porous side of the base it apparently
bonded to it; at any rate the majority of the first con-
traction cracks that appeared in the pavements were
opposite the cracks in the gutter and were undoubtedly
caused by the contraction of the stronger gutter.
ae sae hee Bete kee ac & : ae aiken ~— F che
CONCRETE BaSE FOR ASPHALTIC CONCRETE SECTIONS
ASPHALTIC CONCRETE SECTIONS HAVE GIVEN GOOD SERVICE
Expervment No. 1.—A hot-mixed asphaltic concrete
surface, 2 inches in} thickness, was laid on a 6-inch
1:3:7 gravel concrete foundation. Afcurb of 1:2 mor-
tar 6 inches wide and 2 inches high was constructed
integrally with the foundation along the edge adjacent
to the car track. The concrete base was compacted by
tamping and its surface was slightly roughened by
striking with arattan broom. The bituminous wearing
surface was not laid until a month after the completion
of the foundation.
An effort was made to secure a composition conform-
ing to the ‘‘Topeka”’ specification by using only crushed
rock and limestone dust for the aggregate. This was
found to be difficult without the addition of sand, but
TABLE 5.—Analyses of bituminous concrete mixtures
Experiment Experiment
No.1 No. 2
District of
Topeka speci- Columbia
Coarse aggregate
fication specification
Lime Lime- | -n..,
stone Trap stone © rap
|
Bitumeneeluble insGSeo... ..c2es. -- <osew cee - fol 8.7 6.7 6.7
Sieve analysis of aggregate:
Pass 14-inch screen, retained l-inch sereen_-__j-._.___.|-.-.---. 2.1 | 0
Pass 1-inch screen, retained 84-inch screen. --j..-..---|-.------ 13.2 6. 5
Pass 8-inch screen, retained !4-inch screen_ - - 1.8 2.0 16.7 | 1s, 2
Pass \%-inch sereen, retained 44-inch screen_. - 1L.3 14.0 13,5 |} 1Y, 2
Pass j-inch screen, retained %-inch screen_ _ - 20. 5 13. 0 12% | 1: &
Pass 14-inch screen, retained 10-mesh sieve__.-- 14.5 8.8 6. 5 | 7.4
Pass 10-mesh sieve, retained 20-mesh sieve. .-_- 15.8 17.0 728 | 8. 7
Pass 20-mesh sieve, retained 30-mesh sieve..-- 5. 8 4.3 3.5) 4.0
Pass 30-mesh sieve, retained 40-mesh sieve_._. 3.8 4.0 o. a | 3.3
Pass 40-mesh sieve, retained 50-mesh sieve-.-__| 1.6 2.3 2. 0 1.9
Pass 50-mesh sieve, retained 80-mesh sieve --_-- 3.3 4.4 4.] 4.0
Pass 80-mesh sieve, retained 100-mesh sieve __- 1.5 1.8 1.1 | 1.2
Pass 100-mesh sieve, retained 200-mesh sieve - - 2.9 4.6 2.0 | 2.6
Pass 200-mesh sieve....._-..-.--..-..--------- r 6 6TE 1 12.1 5. 0 | 5.8
4 a ST a ee, ee 100. 0 100. 0 100. 0 | 100. 0
60 PUBLIC ROADS Vol. 9, No.3
owing to impending winter conditions and the conse-
quent necessity for completing the pavement as quickly
as possible, the mixtures were laid as indicated by the
analyses of Table 5. From stationO— 15 to3 +19 lime-
stone screenings were used and from 3+ 19 to 6+ 20 trap
rock was used. The binder was a fluxed native asphalt
of the characteristics shown in Table 6.
The mixture arrived upon the road at a temperature
of about 280° F. Initial compression was obtained by
a 3-ton roller and completed by means of a 10-ton
tandem roller. The surface between stations 4+ 26
and 6+20 was laid during a drizzling rain.
This pavement in general has remained in good con-
dition throughout its 15 years of service and has re-
quired remarkably low expenditures for maintenance.
Depressions have occurred from time to time along the
west edge of section A and to some extent on the north
end of section B, due, apparently, to the tendency of
heavy trucks to follow the line of the gutter. Shortly
after construction slight indications of waviness were
observed, especially near the north end in the trap-
rock section adjacent to the curb. This condition has
not increased to a marked degree, although in a few
places transverse cracks have developed in the base,
resulting in a slight bulge in the wearing surface.
On a number of scattered areas in the limestone sec-
tion, especially near the west edge, the surface has been
broken by the formation of fine irregular cracks.
These areas have remained firm and smooth and have
required no additional maintenance up to this time.
However, it may be reasonably expected that they will
eventually affect the life of the pavement and will
require more maintenance.
Some pitting has occurred, which is more noticeable
in the limestone section, and the section on which trap
rock was used appears richer and more plastic. A
study made on the base showed the condition of the
concrete was fairly well reflected in the appearance of
the wearing surface. Cores were drilled in both good
and poor areas. On those areas over which the wearing
surface was cracked, the concrete base was found to
have suffered pronounced deterioration, in some cases
to such an extent that it could be removed with little
difficulty with a shovel. On the other hand, where the
surface was intact and free from cracks, the concrete
base was also in good condition.
Experiment No. 2-—This is an asphaltic concrete
surface proportioned in accordance with District of
Columbia specifications laid 2 inches thick on the
concrete foundation described in connection with ex-
periment No..1. |
This experiment was also divided into two sections,
stations 64+20 to 9+04 and 9+04 to 12+50, upon
which limestone and trap-rock screenings, respectively,
were used in the surface mixture. In this case, how-
ever, the finer particles of the stone were augmented
by the addition of a coarse sand. Limestone dust as
filler and the fluxed native asphalt binder were used as
in the Topeka mixture. The south 80 feet of this
pavement was laid in a drizzling rain. Analysis of the
mixture as laid appears in Table 5.
After a delay of one week, due to unfavorable
weather, a seal coat of fluxed native asphalt was applied
at the rate of 0.51 gallon per square yard and covered
with clean stone chips. The temperature at the time
was only 35° F., and the asphalt hardened as soon as
TaBLE 6.—Analyses of bituminous materials used in original construction of experiments north of Bradley Lane
| Experi- Experiment No. 3 (surface treatments) Experi-
| ment . ment
| dNaset Nos. 3
; and 2: and 4:
Bitumi- Sections , Sections Sestione Oil-
' nous Sections | D and F:; Band H:| Section CoD and Seamer | emi cement
con- Aand G:| Water- | Water- |E: Fluxed L Flused re Oil T. OIL con-
crete— | Refined | gas tar gas tar native |". eee a it isan ‘tt crete—
Fluxed | coal tar | prepara- | prepara- | asphalt aa ae aSpanit | aSPRay |i
native tion tion ee petro-
asphalt leum
Serio elavityaeo 25>) Coc2 ic... 2c ee Be 2 ee eee a Ae eo 2 1.074 | 1, 219 1.108 1, 144 1.045 1. 043 1.031 1.012 0. 933
Specific viscosity, Engler:
cho US TD (ea meee ed BP at Se OE RSE eae eee ee ce eee le n|ooe eee cee eee oes Eee Soe pel nr | Sian sn 21.8
Uaoo O.,00) CC. 5.2.22 Bae os i= 31 rr err Pee eee | ee 1420 |<... ee eee Soe eee,
oteedmee,. 20° ©. AOUE.. OUBOC. ..... 2 caneemocche Spec eee woes seis ee eee a S| a ee 184 148 1 26 147 |. 22ers
Rilremtesl, G2, 0c. -SeCOmGls:....._ cade wae se doe Senn eae er Bs | eee eens 207 |...---s-ccles-2=-~ 20 Ae
PON Get, 00 -O. pscemmiule:..... 225. deeemee seers Duta eal. AVAIE, adore, RON a. See EN ET EON
Wremmomoint, “OC... eke te seen deseo i ee ee eee OO tae ee een teks wm anna eee 39 48 92 2)
Lossgiltes ., 5 His... 20 eee... eee ss oo so ee 2, BOE dee aerate ees 3. 50 2.73 0.32 0. 59 2. 63
Pemetr on Ol resigtie... =. ee 33.0225 2 nee | ee, ee |. 63 64 1s |
Float test on residue at 32 °C., seconds. __-_. -- Sh Ta 25 ese Pee no eee || ee eee ee ee 5
Bemecm sOluiisiginm Cpe. ...2.. 2. 2-42.c-cene 2 ies a. 2's) | ee 1 ae sec ||. 94, 70 96. 56 99, 74 99, 72 99, 90
Peerenimmeommlein CS>. .......-..--s-scc-05 9-8 bees ++ e-ae besos e Helse = 1,86" | ee | ee 128 ee es . a 08
erreeiiuiniGpmamiC INSOMENNC. ou... --.-seeeeedaeees-ai=scbo,ceeeeseeees-a Oto ee |, = es ee 4.07 2. 09 .09 ail . 02
Per cent itminen insolabheamse® GB.,amgltha.......---.--0._. .-_...--..-.--- 2a cBRe |. 22 ees «|. ee 19, 60 21, 87 34, 84 Palle epee 2051
emo Mi CemCHMOOT..._....... -s225 he aacacee eee ee ee ea 1G yt ee een ee coe ae 9. 83 Ly, 17, 15, 62 T0592 3. 01
Peieenmroe CANNON. 222.0cesd....---.---2...--- nee oe i 16. 29 Q. 25 CN | |
Distillation, per cent by weight:
Wer - 2. = - Se ee eos enol Ee Oy eae ne ee RE ho 2 Se 0. Q 0. 0 0.0 | ~ acne Jae eer Ree he |
(Op oe | i — ee eee i... , 2.5 31.4 $8.1 |... lees
110 to 17 CC. . - Bea ee Ae Wie oo eee ene ee . se, 3,4 BD | ake eR ee Nn ee | | ele
MeO LO 2re ©... een eee oe cee, ee ee eae ae [Bang . #. Sedan | 514.7 316.3 8 G04) |. - ee ee ee
ee a ee 2: 2 SS Re ee EY. en 68.7 ee § 1034 |... 2 ae ee ee ee > eee ||
Me@siMMRe 88s we es SSeS ©. eee a (Aron emer io. 8 64.8 S280... ..235 ee | eeeiec Jnnccnee see
Oba)... nis 99,9 99.9 GORE 2 cig |. .— — . ee.
1 Penetration at 0° C. (200 g., 1 min.) 14; penetration at 46° C. (50 g., 5 sec.) 58.
? One-half solid.
3 Clear.
4 Cloudy.
5 ‘Two-thirds solid.
6 Solid.
‘Clear. Showed 7.5 per cent insoluble in dimethyl suplhate. A 315 to 350° C. fraction showed 7.5 per cent, and a 350 to 375° C. fraction showed 17.5 per cent insoluble
ndimethy] sulphate.
§ Clear. This fraction and also a 315 to 350° C, fraction and a 350 to 375° C. fraction each showed 7.5 per cent insoluble in dimethyl sulphate.
a i
ii
se
CONDITION OF BITUMINOUS CONCRETE SECTIONS IN 1928S.
THE THE UprgerR PICTURES ARE OF [EXPERIMENT 1 AND
THE LoweR 18 oF ExpERIMENT 2
it touched the surface. As a consequence the asphalt
was unevenly distributed and the chips were not prop-
erly bedded, so that most of the stone was swept off
by the traffic during the winter and when spring came
the surface was very soft. <A reapplication of chips in
the amount of 0.011 cubic yard per square yard was
made in July, 1913, and this greatly stiffened and
improved the surface.
The service record of this experiment is virtually the
same as that for experiment No. 1. The surface has a
PUBLIC
ROADS
THe LOWER
EXPERIMENT 1, Nortu oF BRADLEY LANE.
PIcTURE SHOWS THE CONDITION OF THE CONCRETE BASE
WuicH CouLtp Bre REMOVED WITH A SHOVEL
mottled appearance and seems richer than the Topeka
mixture. Wear and depressions near the gutter have
developed and have been maintained with cold patch
mixtures of tar and stone chips. The surface is gen-
erally smooth and unbroken excepting for a few trans-
verse cracks which are reproductions of base cracks.
The trap-rock section, as in experiment No. 1, appears
richer and more plastic than does the limestone section.
Specimens taken from the base show the conerete to be
in good condition generally.
BITUMINOUS SURFACE COAT EXPERIMENTED WITH ON CONCRETE
PAVEMENT
Experiment No. 3.—-This section consists of 4,178
square yards of 6-inch Portland cement concrete
pavement which it was desired to surface coat with a
number of bituminous inaterials.
In mixing the concrete for 1,341 square yards of this
experiment there was added a light fluxed residual
petroleum in the proportion of 5 pints to each sack of
cement, The analysis of this material is shown in
Table 6.
The proportions of the concrete throughout this
experiment were 1 part of Portland cement, 134 parts
of sand and 3 parts of coarse aggregate. The experi-
ment was divided into sections as shown in Figure 1,
and Table 4. Both plain and oil-cement concrete
PUBLIC ROADS
Vol. 9, No. 3
were laid with limestone and with gravel coarse ag-
eregate, the analyses of which are given in Table Ae
The concrete was mechanically mixed to a ‘‘quaky’
consistency, shoveled and raked into place, ee
by means of a strike board, and finished from a bridge
by hand with wooden floats. Expansion joints were
CONDITION OF 2 OF THE SURFACE-TREATED PORTLAND CE-
MENT CONCRETE SECTIONS IN 1914
TaBLe 8.— Materials used in bituminous surface treatments on
> atest omitted and no joints of any other kind were
constructed except those between the several day’s
work. These were placed at an angle of 80° to the
center line of the road; and before work was continued,
the exposed face of the concrete was washed with a
10 per cent solution of muriatic acid, followed by
water. The mixer was of the rotary-distributor
type, now obsolete; and there was probably a con-
siderable segregation of the aggregates.
TaBLE 7.—Mechanical analyses of coarse aggregates used in
concrete Experiments 3, 4, and 5, north of Bradley Lane
Gravel
Size stone | Trap
Pass 2'4-inch, retained on 114-inch screen___.--------.----- 2200 \c..5ecee ae ae
Pass, 114-inch, retained on 1)4-inch sereen_..--.----------- N38. ae Pee.
Pass 14-inch, retained on I-inch screen.._---------.-- -s2s.|)) 2a \} 13.2 6. 6
Pass 1-inch, retained on 84-inch screen__.._..-------------- 25. 8 19, 5
Pass 84-inch, retained on 44-inch screen________-.-------.-- 26. 4 34. 2 40. 6
Pass 14-inch, retained on “A “INeleserOeNl. ...--2-5----+- eee 9.8 47.4 24.9
PRS YG he ee ee .9 5.2 | 8. 4
Det... eee. 100.0) 100. 0 | 100. 0
The fresh concrete was covered with canvas as soon
as practicable and, after it had set, a 2-inch layer of .
loam or sand was spread, kept wet for a period of 8
days, and removed after 15 days.
The bituminous surface treatments were omitted
from the original construction on account of the cold
weather and were not applied until the following year.
In preparation for the application of the bituminous
mat, the concrete surface was washed, swept, and
allowed to dry. Table 8 indicates the nature of the
materials which were applied as protective coatings
and Table 6 shows the results of laboratory tests made
upon the bituminous materials used in original con-
struction.
In certain instances it will be noted that two appli-
cations of bituminous materials were made, the first
being in the nature of a paint or priming coat to facili-
the concrete experiments Nos. 8, 4, and 4, north of Bradley Lane
Maintenance treatments
Location Original treatments
Experi —_, : 7
ment 1916 1922
No ;
From—| To— Paint coat Carpet coat ! Amount
Materials 2 Amount Material 3 Amount
Gallons Gallons Gallons
a 12-F50 | 15--O0 WRPWONC. 2.22222 eee. @oaltar, retingd.-.._--.-. 0.33 | Water-gas tar preparation 0.307 | Coal tar, refined_....-...-- 0. 385
| 1542000; 17-+-50' |... do- abot _| Water-gas tar preparation wu. 22-2 Siig cee ae eet ceo Si Wosnes 0 0 age es gee RY » 885
No. 2.
Oe 2 .--| Teeo0| ZO nOie 22-8 d02ae624 ese es | ixed mative asphalt 50 | Residual asphaltic petro- 4 A ena (¢ oP NIT, 8 bn . 385 |
No. 2. eum
42D aie 20+00 | 21+25 eee tar preparation |..__- yee Oe | fl pee (10... ee es 2 ton eee CO eeeeteen 3c. . 385
| 0. 1.
38-E___..} 21+25 , 22+50 | Native asphalt emulsion 4..| Fluxed native asphalt No. S|. & W256 i ktememeeees 5 GM ee oe tc eee . 385
le
San. - .-.|224-00e|625-1-00 Visa einen tar preparation | Oil asphalt No. 1.._---_--- 60) LC: ea a AE Te ae Gee. ..-<ocaeeeeeeee = . 385
Onl.
ot Coac00', 204-000) INONC sue cnn os eee Coal tar, refined____._____- ,a6 Waist -gas tar preparation. rc a ae U3 — a2 Se . 385
i eeeoU! | 2800s. . . do. _...2-2 on mes tar preparation Poot een... ys | Ea eee Ds eo. 2. SU » 385
oO. 2.
a 285-00 | 29-260) |. ..2e AO weeonneconcnce ee Fluxed native asphalt No. 50 | Asphaltic petroleum ___-_- #409 |... NOs sacece2- nee ~ 385
Ze
a 29+-50 | 304-90 |___-. plie>....:. 22222. Oil asphalt No. 2.__._.___- et eee oe (ib. 2S uae oe OO | See... Oe... (Gee... oe 2385
j30+90 33-+60 il
yee eee: 442+50 , 44461 OP GWE®. . 8 ne (8015; 5) ne hr NOner |) NDC: .. <2. ee None.’ |... - Gime... 262. aes ee = . 260
\46+10 | 494-00 ||
33-60 | 37-+85 |
! = i
5 aes ra | irae; } an, ae i (2 er None. |.---- G68... J: oes None. |___-- a) i cane 260
| 49+-00 : 52+00
|
Cover consisted of limestone screenings or pea gravel.
2 ‘Torpedo-sand cover.
_
3 Pea-gravel cover. _ ;
4 Same type of bituminous material used in experiment No. 11.
May, 1928
PUBLIC ROADS
63
tate the adhesion of the heavier carpet material. The
first application was broomed over the concrete without
heating. The heavier products were heated in kettles
and spread by means of a hand-drawn distributor.
The treatments were covered with pea gravel or lime-
stone grit and immediately opened to traffic.
The bituminous mats were purposely permitted to
wear without maintenance and in February of 1916
were reported to be in the following condition:
(A) Refined coal tar. Twenty to twenty-five per
cent of the treatment worn off. The west side showed
more exposed concrete than the east side.
(B) Water-gas tar preparation, No. 2. Slightly
better than A, but deteriorating.
(C) Fluxed native asphalt, No. 2. Eighty-five per
cent of the mat was gone on the west half but only
about 1 per cent had disappeared from the east half.
(D) Fluxed native asphalt No. 2 over water-gas tar
preparation No. 1. About 85 per cent had disap-
peared from the west side and about 5 per cent from
the east side.
(I) Fluxed native asphalt over native asphalt emul-
sion. About 85 per cent worn off of the west half
and about 10 per cent from the east half.
(F) Oil asphalt No. 1 over water-gas tar prepara-
tion No.1. Only a few scattered patches of the treat-
ment remained.
(G) Refined coal tar. Surface treatment was worn
off to a great extent over the entire section.
(H) Water-gas tar preparation No. 2. Seventy-five
per cent of mat had worn off of the west half of the
pavement. The east half remained almost intact.
(1) Fluxed native asphalt No. 2. About 60 per
cent of the treatment was gone from the west half.
The east half remained almost intact.
(J) Oil asphalt No. 2. About 35 per cent of the
surface treatment had disappeared from the west
quarter of the pavement. The remaining three-quarters
was almost intact.
The mats of sections A to F, inclusive, were laid on
plain concrete. The concrete of sections G to J con-
tained oil as previously described. Although earlier
observations had indicated that oil-cement concrete was
not better adapted to bituminous surface treatment
than cement concrete, a comparison of these groups, on
the basis of observations made three years after con-
struction, leads to the conclusion that the asphaltic ma-
terials at least, proved somewhat more durable on the
former.
The west half of the pavement carried much heavier
traffic than did the east half, and this condition is
clearly reflected in the behavior of the bituminous
treatments.
During the fall of 1916 the entire experiment was
once more surface treated with bituminous materials.
Sections A, B, G, and H, which originally had tar mats,
were at this time treated with a hot water-gas tar
preparation. A residual asphaltic petroleum was
applied to sections C, D, E, and F, upon which materials
of an asphaltic nature had been previously used.
Sections I and J received a carpet coat of cold asphaltic
petroleum applied at the rate of one-half gallon per
square yard in two applications. ‘Torpedo sand was
used as the top-dressing for all of these treatments.
By 1922 these mats had virtually disappeared and
refined coal tar with pea gravel was applied to the
whole experiment at the rate of 0.385 gallon per square
yard. Inspections made in 1926 and again in 1927
showed that the last treatment had for the most part
worn off, although on the east side considerable areas
remained intact, especially in the gravel oil-cement
section, and small patches were scattered over the
remainder of the surface.
All the sections in this experiment are in poor condi-
tion and will require heavy maintenance from now on.
Very little difference in appearance is noted between
the gravel and crushed-stone aggregate and between
the cement and oil-cement sections.
CONDITION OF SURFACE-TREATED CONCRETE SECTIONS IN
1928, ExpEeRIMENT 3-B. THE Upprer Picturr SHows
CONCRETE Not CONTAINING OIL AND THE LOWER Pic-
TURE SHOWS OIL-CEMENT CONCRETE
PORTLAND CEMENT CONCRETE TEST SECTIONS DESCRIBED
Experiment No. 4.—This was a test of Portland
cement concrete mixed with oil as a wearing surface.
Gravel, limestone, and trap rock were used as the
coarse aggregate and, due to irregularity in the delivery
of these materials, it was necessary to separate the
sections in which they were used, as shown in Table 4.
The concrete mixture was composed of 1 part Port-
land cement, 134 parts of sand, and 3 parts of coarse
ageregate. After the cement, aggregates, and water
were partially mixed, 5 pints of light residual oil was
added for each sack of cement and the mixing com-
pleted. The analysis of the oil is given in Table 6.
The construction details of this experiment were
identical with those of experiment No. 3 which has been
described.
Hydrated lime was also added to the concrete con-
stituting 153 lnear feet at the northern end of the
section containing trap-rock coarse aggregate. The
64 PUBLIC ROADS Vol. 9unvene
BX SRP ERE LEY!
STEPS IN THE CONSTRUCTION OF THE CONCRETE SECTIONS AND CONDITION OF A PORTION OF THE FINISHED
CONDITION OF CONCRETE SECTIONS IN 1928. Tue Upper
PictURE SHows EXPERIMENT 5-A AND THE LOWER
PicrurE SHows EXPERIMENTS 4—-E anp 5-D
V = y “ Ae E, aig -
nee ait pile ~ .. eo
BADLY CRACKED CONCRETE PAVEMENT IN 1928 WuicH
PrRopucED Cores oF Farrty HicH STRENGTH
proportions of this mixture were as follows: Hydrated
lime, 20 pounds; cement, 188 pounds; sand, 4 cubic
feet; coarse aggregate, 714 cubic feet; oil, 10 pints.
Table 7 shows mechanical analyses of the coarse
ageregates employed in the concrete experiments.
trperiment No. 5.—This section was identical with
expermnent No. 4, except that oil was omitted from the
mixture. The same coarse aggregates were used and
the experiment was constructed in separate sections, as
shown in Table 4.
Hydrated lime was added to the conerete of the trap
section adjacent to the oil-concrete area in which
hydrated lime was included. The proportions were
the same as in experiment No. 4, except, of course, for
the omission of the oul.
The wearing quality of the concrete seems not to
have been affected by the presence of the oil. Both
types have worn uniformly and disintegration has not
May, 1928
ROADS
developed except where the pavement has cracked so
badly that the small slabs have been progressively
broken into still smaller pieces.
In the sections using trap rock the abrasion of the
mortar has left the more resistant coarse aggregate
prominently exposed. .
At the present time nearly all of the sections are
badly cracked and certain areas are maintained with
the greatest difficulty. The sections located north of
Blackthorn Street are in the best condition of the con-
crete group, with transverse cracks frequently located
at greater than 25-foot intervals. This may be due to
the better drainage conditions existing at this point.
STEPS IN THE CONSTRUCTION
In 1922 these experiments were surface treated with
a hot application of 0.26 gallon refined coal tar and
pea gravel. This mat surface has now entirely disap-
peared except for two small isolated areas.
The presence of hydrated lime in portions of the trap
rock sections of experiments No. 4 and No. 5 apparently
hasnot affected the behavior of the concrete. Coreswere
taken both from the badly cracked portions and from the
larger areas of the various sections of the concrete experi-
ments. The compressive strengths of the two types of
cores are approximately the same and consequently are
not indicative of the true condition of the pavement.
In the summer of 1914 and subsequently at other
times, expansion of concrete sections resulted in a blow-
up at station 12+ 50, the junction of the second bitumi-
nous concrete and the first concrete section, and a point
at which there is a convex vertical curve. Removal of
a strip of concrete on each of the several occasions
finally put a stop to the phenomenon.
PUBLIC
BRICK TEST SECTION SHOWS BUT LITTLE WEAR
Experiment No. 6.—This section included tests of
vitrified brick wearing surfaces on a Portland cement
concrete foundation. The foundation was constructed
of 1:3:7 gravel concrete as in experiments No. 1 and
No. 2, except that in this case the curb was made 8
inches wide and 6 inches high of 1: 134:3 gravel con-
crete placed integrally with the base.
On the foundation a cushion of sand was spread and
rolled with a 300-pound hand roller and struck off to a
true depth of 2 inches. The brick were laid in straight
courses at right angles to the curb and no driving was
permitted to straighten the courses.
After the brick
OF THE Brick EXPERIMENT AND ONE OF THE FINISHED SECTIONS
were laid and imperfect ones replaced, the surface was
rolled with a 5-ton tandem roller until they were firmly
bedded in the sand cushion. Portland cement grout,
composed of 1 part cement to 1 part of sand, was applied
in two applications. The first was of such consistency
that it would flow freely and was swept into the joints.
After the first application had settled well into the
joints, the second application of the consistency of thick
cream was squeegeed over the pavement, leaving the
joints well filled. Immediately after the grouting was
completed, sand was spread over the pavement to a
depth of one-half inch and kept wet for seven days.
Longitudinal joints were provided along each curb,
but no transverse expansion joints were constructed,
and the ends of the pavement were practically fixed.
The experiment was constructed with brick obtained
from many sources and possessing widely different test
characteristics. Results of tests made upon samples
of the brick laid in each section are listed in Table 9.
PUBLIC ROADS
Vol 9, No. 3
TaBLE 9.—Tests on vitrified brick used in experiment No. 6 north of Bradley Lane
[Length of section, 978.1 feet]
Water
Section | Length Type of brick a ad absorp-
a tion
Feet Per cent| Per cent
a. 51.5 | Shale, wire-cut lug.....-.- 211, 1. 39
ees. Tee tiie Olea I ow sax SS 16. 36 1.31
108.7 | Shale, re-pressed _...----- 20,07 . 88
.. .=...- 15. 0 las222 Mn. 3 Seo on oe ee 17. 67 1. 65
| eee Die 4 eS. a ee 22. 04 Lalo
2 Gundy |e CU oe oa a nee oe 18, 80 Metall
@....-. GURS |_..-2 ) |e oe 5 ee, Sa Dia Oe 2. 29
): ae aio Oe ae es... cl ee we aS 22. 68 3. 74
| ee MO) We eee (ein aR 2 c= 22. 59 2. 86
ee 61.3 | Fire clay, re-pressed _._.-- 19. 11 1. 56
very hard.
) ane ee oe CM eee 0.) eee 37. 68 2. 38
uniform.
Dceprege: . 58.8 | Shale, re-pressed _......-- 38, 89 4.04
uniform,
i 60.1 | Fire clay, re-pressed -..__- 24, 31 3. 73
a 51.3 | Fire clay, wire-cut lug....| 31.19 3. 68
Tue Upper Picturt SHows CoRES TAKEN FROM THE CON-
' CRETE SECTIONS AND THE TWO LOWER PICTURES SHOW
CORES FROM THE BRICK SECTIONS
Sections K, L, M and part of N were constructed
over a heavy fill which some years ago settled to a
considerable extent, causing failures in the overlying
pavement necessitating heavy repair during 1919,
1920, and 1922. The cost of such repair is not prop-
erly chargeable to surface maintenance and therefore
has not been included in the accumulated cost data of
Figure 2 and Table 1. <A foundation failure occurred
also at the junction of this experiment and the adjoin-
ing concrete pavement. This was apparently due to
expansion of the concrete, and the brick on a strip 2
feet wide across the section are cracked and worn.
The brick of section N are rough and badly broken.
The mortar grout is generally in good condition,
and in several sections, notably those of wire-cut
brick, the joints are filled to the top. In no case is
the mortar disintegrated, but directly in the traffic
lanes some joints are unfilled to a depth of about one-
quarter inch. This is particularly true of the sections
paved with re-pressed brick.
eee eeeeEEeEeEeEeeeeeSSsSsSssssfh CO
Description
Hard-burned brick having a good structure.
Medium hard-burned brick having a very good structure.
Brick well vitrified; losses in rattler mainly due to chipping.
Brick molded from coarsely ground shale; had a fairly good structure and was hard burned.
Brick very hard burnea; losses in rattler due to chipping.
Brick molded from coarsely ground clay; had a good structure.
Medium hard-burned brick which wear evenly though excessively in the rattler test.
Medium hard-burned brick made from finely ground clay and having a fairly good structure.
Medium hard brick made from coarsely ground clay and wearing down uniformly in the rattler.
Brick made from coarsely ground fire clay; had an excellent structure, free from laminations; not burned
Comparatively soft-burned{brick made from coarsely ground fire clay; wear in rattler excessive though
Comparatively soft-burned brick made from coarsely ground clay; wear in rattler excessive though
Fairly soft-burned brick'made from medium finely ground clay; worn down evenly by rattler.
| Losses in rattler due mainly to open laminations; brick burned hard.
No transverse cracks exist in the experiment although
a considerable number of fine longitudinal cracks have
developed and sometimes extend through several con-
secutive sections. However, they seem not to have
affected the bahavior of the wearing surface which still
remains in excellent condition and shows no evidence of
raveling. Except for the repair of defects directly
caused by subgrade and foundation failure, mainte-
nance on this experiment has been confined to the filling
of these cracks with bituminous material.
A slight amount of pitting is noticeable in sections.
L and N in the traveled areas but on a major portion
of the sections the surface has the same smooth unworn
appearance as originally.
At the time of construction two courses of brick from
each section were measured before laying and a record
made of their thickness and location in the pavement.
In February, 1928, a number of these brick were re-
moved from the heavily traveled areas and measured.
The results of these measurements are given in Table
10. Sections not appearing in the table gave indications
of no wear and consequently were not measured.
TaBLE 10.—Loss in thickness of brick taken from portions of
pavement subjected to greatest wear
Water
: ’ Rattler Measured
Section Type of brick face abe wee
ion
Per cent | Per cent Inch
(Ae ee Shale, wire-cut lug.._____._______--------- Pa ing . 39 0. 08
Bee. COS 2 oe. oc. ee oo 16. 36 1.31 . 00:
Geo Mitele, T6-PierseG.__ 22. skeen scucuanses 27. G2 2.20 . 06
pS Cee. ire clay, Te-presswe..........--------c.--- 37. 68 2. 38 pei
yon eee Shale, re-pressed__.......__.__..-...-..--- 38. 89 4.04 a
Nae. 31.19 3. 68 .70
Wire clay, wire-cut lWg___..._..........28e8 |
In a few isolated cases individual bricks show circular
scaled areas indicative of internal laminated structure,
while some other bricks have cracked but have not
spalled and would not be noticeable to the casual
observer.
With the exception of section N and the sections
located over the unstable fill, whose failure can not be
attributed to the nature of the surface, this experiment.
is in excellent condition.
No deterioration in the concrete base was found
such as was noticed on certain portions of experiment
1-A although that portion over the fill was badly
broken.
May, 1928
COMPARATIVE DATA ON TEST SECTIONS PRESENTED
The accumulated maintenance costs of the six sec-
tions north of Bradley Lane are given in Table 1, and
the costs by years are shown graphically in relation to
the traffic in Figure 2.
The results of a crack survey of all sections made in
February, 1928, are plotted in Figures 3 and 4, and
digested in Table 11.
Table 12 gives the result of tests of cores taken from
the concrete pavements and bases, and Table 13 shows
the results of analyses of samples of bituminous con-
crete taken from experiments 1 and 2, the samples of
both materials having been taken in February, 1928.
The two bituminous-concrete experiments and the
brick experiment, exclusive of that portion over the
fill, have required the least maintenance up to this
time and are still in excellent condition and to all
appearances should continue to give economical service
for some time to come.
On the other hand, the concrete experiments have
required comparatively heavy maintenance and, with
the exception of the north 1,400 feet, are in very bad
condition. To what extent the deterioration of these
sections has been caused by the impact resulting from
the rough condition of the surface which was developed
when the surface mats were allowed to wear off in
patches, is problematical. That the lack of mainte-
nance of these mats has to some extent caused cracking
of the pavement, is a probability. The maintenance
TABLE 11.— Digest of condition survey made in February, 1928
BITUMINOUS CONCRETE
Per cent of section in— Cracking per_100 feet
Section No. . At —— P —_ |
rans- ongi-
Class 1! | Class 22 1 Class 3 3 verse | tudinal Corner
Feet Feet ' Number
Lo a ee 60 8 328 109 29 OF
la | oe) | Sees iA 66 | 3 | aff
o>) Vi 3 20 7 | 4 eee
Oe. ../.--------.-- | 93 6 itl le, | aaa
PORTLAND GHRAGENT CONCRETE
| | Cracking per 100 feet
Comgued ea
. wi : : :
meen surface oes. " Broken | Transverse Longitudinal
eee treat-
ment |
ment Not Not
| , Covered | aoverea | COVETED | covered
Per cent | Per cent | Per cent | Feet Feet Feet Feet
Co) || Ohne <2. ain 2 A Pr. 391
* oe 9 89 a 23 i iol 388
eC... 2... 74 90 3 ee eee ; 437
— — — —=. - 95 oe A) | iil
62 | 26 12 | 106 405 76 187
>) 1 91 Rp ss | a S7
[a 3 | &9 Slee 1 430
|) ee es 99 - | 290
) OS 1 ae, J 27) a Za
a ee OM i ates See 17 | reer Pai Fh
C-lb ee| ———e NOON |Beteee oe eS AQa ere oe. SL 126
eee |. .-....--! | ee | ne 125
BRICK
Section._..........-- A,B pCc|D| Blew) a|H|1/s|K\/u|MiN
= bt | ef Se - |
Longitudinal cracks | | I |
per 100 feet (in
ee. __...-.....2 550 |332 195 620 ; 73 |606 496 723 480 |196 403 735 800 | 488
Per cent of section
broken or replaced-
fe | ee te
21| 31
Tlecdlebeeledeebeobehnl a?
! Smooth, without surface cracking.
4 Moderate surface cracking and slightly uneven. :
3 Excessive surface cracking, marked unevenness, maintained or patched areas in
combination or separately.
PUBLIC ROADS
67
g-
CONDITION OF Brick SECTIONS IN 1928
work now being done does not improve the condition
of these experiments as concrete pavement but serves
somewhat to keep them serviceable. In spite of the
badly cracked condition of these sections there is no
appearance of settlement or subgrade failure and, for
this reason, those areas which seem to have reached
their service limit as a concrete pavement might econom-
ically serve as a base for some type of surfacing.
68 PUBLIC ROADS Vol. 9, No.3
0+00 ae LANE , 1+00 2+00 3+00 4+00 ROSEMARY ST. 5+00
bIA BITUMINOUS CONCRETE-TOPEKA SPECIFICATION -LIMESTONE IA+1B BITUMINOUS CONCRETE- TOPEKA SPECIFICATION-TRAP ROCK
+00 10+00 11+00
6+00 7+00 8+00 2 4 3 9+0 2 2
BITUMINOUS CONCRETE-TOPEKA SPECIFICATION-TRAP ROCK
ZA+4+28
SYMBOLS USED FOR SHOWING CONDITION OF DIFFERENT SECTIONS
EXPERIMENTS | AND 2 ~ BITUMINOUS CONCRETE
| - SMOOTH, WITHOUT SURFACE CRACKING UNBROKEN LINES REPRESENT CRACKS
2- MODERATE SURFACE CRACKING AND SLIGHTLY UNEVEN BROKEN LINES REPRESENT CHANGE IN CONDITION
3- EXCESSIVE SURFACE CRACKING, MARKED UNEVENESS, MAINTAINED SHADED AREAS REPRESENT REPLACEMENTS
Zila OR PATGHED AREAS IN COMBINATION OR SEPARATELY *{8-LOCATION AND NUMBER OF CORE
Fre. 3.—Conpition Cuart or Biruminous CoNCRETE EXPERIMENTS IN FEBRUARY, 1928
32 13+00 14+00 15+00 MACADAM REPLACEMENT 16+00 17+00 18400
EGA - Z PER dt pk AL ph et es) ateot jie eS ann.
Sus cans S 4 PS ae aes os
BAAD Ih Mees tae oft op SIMIAN
3A CEMENT CONCRETE-GRAVEL-SURFACE TREATED 3A+1- 38 CEMENT CONCRETE -LIMESTONE- SURFACE TREATED
19+00 20400 THORNAPPLE oh 21+00 22+00 23+00/UNDERWOOD ST.
A OS ie = ,f-/ BANS (td
peak ieee aes sii — iS a al
POSER REE
| 3B---3C
24+00 if 25400 Low _MIRGILIA ST. 26400 27+00 28400 WOODBINE ST. 29+00
Ve Se De Sr -——._-s_,'"—) a ee
5 ee are eae reer oer oe es Sa ae ae i
Ao Oa eS oe ceed | A Cne re LL es SAMA Ss ae :
AMR GT 98 9 B= La MO? Hoar whaw iia Calli fawavitiM@ysmasin on eer mado eoene :
CEMENT CONCRETE-GRAVEL-SURFACE TREATED 3C--3A OIL CEMENT CONCRETE-LIMESTONE-SURFACE TREATED 3A7+3B
4 30+00 31+00 42 LELAND ST. 32+00 33+00 34+00 ASPEN ST. 35+00
Ia 7 ——- Slemiemeees=s | Hate Severe
. = 4 ari C—J
: ae me, iim SC SET ESSE = ay |
co Ce Aen Oa A a (A SA
(me eee, : Feta
OIL CEMENT CONCRETE-GRAVEL-SURFACE TREATED 3B-—-+«4C O|IL CEMENT CONCRETE-GRAVEL
ACSA
35400, ASPEN BLACKTHORN ST. 36400 39+00 40+00
SEES Se Cane crocs ee Po) I ae ee ime eee
sanity semaines ae Poe JPR el eee
4 \HIGH CEMENT CONCRETE -GRAVEL SA—b-5B CEMENT CONCRETE - LIMESTONE
CYPRESS ST al400 42+00 43400 4h+00 45+00 46+00
D Pee eee a ee
tat le IA GY oT FD on es ee A coe a
met eee nae ee Ph (SEAS cs ata rh} aa =e ja B (| 3
5B—+-4D OIL CEMENT CONCRETE-LIMESTONE 4D 5SC CEMENT CONCRETE-LIMESTONE 5C>r-4E
47+00 48+ 00 49+ 00 54 50+ 00 5| +00
OIL CEMENT CONCRETE - TRAP ROCK 4E-+=-5D CEMENT CONCRETE-TRAP ROCK
52+00 ; 53400 54+00 55+00 56+00 57+ 00 3
°55 =o — ee SSS oS | SS
—3 a oOo
He
END ofFa~ BRICK Aw 8B B te C BRICK C+D BRICK D) Sane BRICK Efi BRICK F —--h-G
PEMenETE 58+00 59+00 b 60+00 9 {1 61+00 12 62+00
———— See a ——
CHEVY CHASE LAKE
CH BRICK H+] I+ J BRICK = J +#K K tL t-++m prick men
SYMBOLS USED FOR SHOWING CONDITION OF DIFFERENT SECTIONS
EXPERIMENTS 3,4,5 AND 6 - CONCRETE AND BRICK
UNBROKEN LINES REPRESENT CRACKS SHADED AREAS REPRESENT CRUSHED OR REPLACED AREAS
CROSS-HATCHING REPRESENTS SURFACE TREATMENT STILL INTACT *33-LOCATION AND NUMBER OF CORE
Fig. 4.—ConpiTion CHART OF CEMENT CONCRETE AND BriIcK EXPERIMENTS IN FEBRUARY, 1928
May, 1928
PUBLIC ROADS
69
TABLE 12.—Tesis on concrete specimens taken from experiments north of Bradley Lane during February, 1928
a ooueSeeeeSFSeSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSeeeeeeee
i
Speci-| Experi- | Distance | Depth | Com-
men ment and) Station |from west Type | of con- | pression Remarks
No. | section | edge | crete | strength
Pounds
per square
Feet Inches inch
15_.....| I-A..... 0+57 Ooi COMmpeC Gees. 2) 2. ok oslo cewan-|eee------< — ewe! y over transverse crack; concrete base sound though cracked
ransversely.
6p...) l=A...--: 1-34 » | eee i en i Se Taken from badly cracked area; concrete badly crushed; no core obtainable.
i || Ye 1+-88 a 0 a ee oa eee re eee Same as No. 16.
18.....| 1-A._.--| 2+00 1-0) | en (Gree a ee ee oe eee 8. Base cracked horizontally with no surface indication of failure.
1m. ..| 1-A....-- 2+89 Gh COs oe eet oe Sak 6. 0 3, 140 Sound structurally.
Zim-..| 1-B.-.-. 4+-79 SS Open ae 5. 5 3, 380 Taken from good section of pavement.
@e_..| 1=B...-- | 5+00 es) Qe Sie ee a eke moe... 03 ae Taken from transverse crack; concrete shattered.
aee.-| 1.8 | 5+29 ileal) | eae Ce ee 2 ee a Mer cracked but badly shoved; concrete appeared to be weak and
isintegrating.
Zem...| 1-B-.-.-- . 5-+-51 es Pe 0) ae Re ec laoe eam nn seeamomeed Top surfacing good; concrete base apparently sound on top 3% inches; bottom
| portion disintegrated.
Zp) 2-A _ _..- | 6+55 Ue Le BAUS sll ees Top surface good; base appears to be somewhat crushed.
go--| 2 A.-..-| 64-79 1B | ae CU Re Oe nome eee eee ee ame badly cracked and wavy; concrete crushed and craeked in all
| irections.
Ziee...| 2=A..-.- 7-+05 i ne oes ae en al Taken on transverse crack; surface good; concrete specimen taken in small
pieces; base crushed.
28_...) 2-B._.-- 9+-85 2.0 |.-.-. CS eee coe | —, ots i of top good, but cracked where specimen was taken; con-
crete crushed.
208 ..| 2B. ..-- 10-+67 rs rs Re 2 a eee ae eee ee 5 Top good; concrete solid for first 4 inches; crushed and loose below.
a02.-.| 2-b...-- | 10-87! 4.0 | sees OPS Seen a ee Ce |): ee Taken on transverse crack; concrete shattered.
eo) eos. ---- H--75 Ue eee (EO ys re. aeed 6.5 3, 400 Top and concrete in good condition.
3$2..-..| 3-A_._-- 12+-67 6.0 | 1:134:3, 6-inch gravel concrete-_-- 6.0 |15,430+ | Taken from badly cracked area.
‘el Sy. 14+53 TS Opie. 10), i mem 0 6, ele Taken from uncracked slab 7 by 15 feet.
ode..-.| o-B_...-| 17+77 5. 0 : Pus 3, 6-inch limestone con- 5.5 |15,610+ | Taken from badly cracked area.
crete.
jo ..| s=B._..- 18+37 Veale... 10: ee ee men 6. 0 5, 550 Taken from good section; uncracked slab 9 by 51 feet.
ote. ..\ba-C.-... 224-03 7.5 | 1:134:3, 6-inch gravel concrete-_.- 6.0 | 15, 280+ Tage im nest of cracks; general appearanee bad; core taken from slab not over
18 inches square.
Bae 2NB=C __... 24-+55 ks: EC ne 5.5 |15,750+ | Taken from uncracked slab 5 by 18 feet
36_...| 3-A__... 25+-75 15.0 | 1:134:3, oil-cement concrete, 6; 5.5 5, 100 Taken from uncracked slab 8 by 33 feet.
inches thick (limestone).
A = 26+99 | Bice s ee a meee 5.5 |15,130-+ | Taken in nest of cracks; slab measured 10 by 24 inches.
age ._.| g-B._._. 27-51 12.0 ' 1:134:3, oil-cement concrete, 6 ooo 4, 290 Taken in nest of cracks; slab measured 12 by 24 inches,
| inches thick (gravel).
ie. .| eo... n 2 29+63 1 oe ee JO ae 6.0 2, 960 General appearance in vicinity of specimen good; core porous.
ae...) 4-C_.... ol+-12 bE Pe 0 see Ole J. | 6.0 3, 240 Taken from slab 444 by 15 feet; core porous.
ap...) 4-C_.... 32+34 12507 2. DO... ee Sie 2 eee / 5.5 | 4,500 | Taken in nest of cracks.
Qae..; O7A----- 35+35 9.5 | 1:134:3, 6-inch gravel concrete_..; 5.5 /|15,330+ | Taken in nest of cracks; surface cracked in all directions,
45__..| 5-A____- 37+71 ee... lo. .————— Sie 6.0 |15,380-+ | Taken from slab 6 by 6 feet.
ae__! 6-B__._- 39+14 : 1320 ae 6-inch limestone con-! 5.5 4, 520 Taken from slab 10 by 20 feet.
crete.
i 41+50 ce) CS aii on 5.5 |14,880-+- | Taken in nest of cracks; surface cracked in all directions.
48__..1 4-D___.. 43+91 13.0 | 1:134:3, oil-cement concrete 6 5.75 | 4,050 Taken from slab 8 by 38 feet; adjacent surface not so badly cracked.
inches thick (limestone).
Agee.) 4—D) 44++54 pk ei): ee Sc ee ofo)| 0,010 Taken in nest of cracks from slab 114 by 3 feet; surface badly cracked; core
porous.
O0ee..| 5-C__.__ 444-93 9.5 | 1:134:3, 6-inch limsetone con- es fs al ees a From small slab; road badly cracked in network; core too short for test.
crete,
meee.) o-C_. ce 45+81 Issgieeees O10 ene oe 6.75 | 5,040 Surface generally good; core from slab 914 by 15) feet.
G25---| 4-E..... 46+47 | 12.0 | 1:134:8, oil-cement concrete, 6 7.00 | 3,870 Surface generally good; core from slab 7 by 69 feet; core slightly porous
| inches thick (trap).
oae__.| 4-E__... 47+15 tea eee D0) i 6.75 | 4,630 Surface generally good; core 1 foot from transverse crack,
wae ..| 5-D....- 49+-71 6.0 | 1:134:3, 6-inch trap ¢oncrete-.-_-__- 6.75 | 4, 800 Surface generally good but slightly pitted.
oaee.., O-D___.- 51+92 4 Opies e Nn 6. 0 4, 530 Surface generally good
ee) G-A_....| 624-25. 1 4.0 | 1:3:7, base under brick_....-_..- 55 3, 380 Base concrete in the brick sections did not show indications of disintegration
a2 4.6 _—_ 57+40. 3 4. ote (10). el es Re G3 3, 835 excepting on the west side of sections K, L, M, and N where it was badly
2 | 59-+75. 4 [omens C0) ee ten aes es) 3, 790 broken over the fill,
e..| 6-t..--- 60+-25. 5 7. Sales RD ee Nee 2 ee ee 5.0 3, 660
ie. .|) Gem... _|._..-..<-. (Oller OOS oct. See eee eee eee ee 6.5 3, 360
ie | G-Wl_._..|_.....-<.- 40 3 EEE: °° Rang a te On SSE ft | ec
ia i 614+-34. 9 Coleen c= Chee eee snacacaceckee sc 0 2,170
eee IN 1... 61+-34. 9 iC.) ee oo 6.8 3, 210
1 Maximum load applied and specimen not broken. Variation in maximum-load value due to factor applied to correct for height of specimen.
TABLE 13.—Results of analyses of samples taken during February, 1928, from the bituminous concrete Experiments 1 and 2, north of
Bradley Lane
| |
NE eed. 2 apg) SU oak vs da Shines Sad aes secede oe nese 29947 | 29948 29949 29950 29951 29952 29953 | 20954 29955
TRE ih do on on oS he ew bce wedecccccecedcusussuss | No. 16 No. 18 No. 20 No. 23 Noes No. 24 No. 26 , No. 28 No. 29
; (thin) (thick)
a ee 1-A 1-A 1-B 1-B 1-B 2-A 2-A 22 Bios 28
IR Poor | Good Good , Shoved | Shoved | Good Poor Poor , Good
(cracked) | (cracked)! (cracked) |
BE 6 a Average | 134 to 275| 2}4to27%| Lto1l4% | 24 to3 | 24 to 234| Average | Average ; 2 to 24
‘1M%inches, inches inches inches inches inches {14% inches 2inches | inches
{ | i
\ ' {
Per cent | Percent | Percent | Percent | Percent | Percent | Percent | Percent ; Per cent
ene IN 2 <=. es. see es --- ----------------.------ 6.8 6.8 8.0 | 8, 2 7.6 6.0 5. 6 5. 4 | bag
fees We inchesereen, retained on l-inch sereen....-.-.-----...-.------------- -..--.---- 1 Ia a ics ge tall ee See OE ens gS |----e2e-e- | 6.9
ae eer eeneen, reedines On °4-inch eepeen _..._..-...--------------------- | nn nn en ene n nnn ene en ee ene le enn en eee 9. 2 0.8 | ae Lin?
ee. 4 -1meh Screen, rétaimed on }4-inch sereen____._........-.----.----------'.-..------ ---------- 4.0 26 4.0 16. 5 5.0 | 9.9 6.4
Haee?4-imeb screen, retained on }4-inch sereen__._.....------.0------s--s---- 9. 0 10.8 14.2 12.0 11.8 16.6 19.6 | lee 18. 6
Pass 14-inch screen, retained on 10-mesh sieve.........--.------------------- vat 22.0 15.0 137 16. 4 15.6 25.4 | 13,2 15.4
Pass 10-mesh sieve, retained on 20-mesh Sieve._.....-------------------------! 22. 6: 21.4 17.8 | Lisa 18. 0 9.6 13.8 9.4 9. 6
ase 20smeshesieve, retained on 30-mesh sieves_-_._.....-.-...---------------! 7.0 6. 4 6.2 | 6.2 6.4 3.4 4.0 a , 3.3
Pass 30-mesh sieve, retained on 40-mesh sieve__........-..----------------- Le 5.5 5. 0 4.8 5. 2 | 5. 2 3.8 4.2 | aay B.2
Pass 40-mesh sieve, retained on 50-mesh sieve...___._...--------------------- 4.0 | 3. 6 4.0 4,5 4,2 4.0 4.0 3. 0 | 3.2
Pass 50-mesh sieve, retained on 80-mesh sieve.....___.-.--------------------- 4.8 4.3 5a | 6. 0 5.8 5.0 4,7 | 3.8 4.2
Pass 80-mesh sieve, retained on 100-mesh sieve..._...-.---------------------- 2.3 | 2.0 2.0 2.2 2.0 Ly 14 | 1,4 | Nap
Pass 100-mesh sieve, retained on 200-mesh sieve..____......------------------ 3.5 3.5 3.7 6.6 5.9 3.0 2.8 | 3.0 3.7
eeerGeerten eos. 28 see ee +_ oie ee 7 18.5 14,2 15.0 | 151 a 6.1 5.7 | 7.4 7.4
A CANTILEVER re oe FOR MORTAR
Reported by D. O. WOOLF, Junior Materials Engineer, Division of Tests United States Bureau of Public Roads
HE Division of Tests of the Bureau of Public
Roads has recently designed an apparatus for
testing cement mortar beams under cantilever
loading which is similar in a general way to that devel-
oped by the Illinois Depar tment of Public Works for
tests of concrete and described by H. F. Clemmer in
the May, 1926, issue of Pusiuic Roaps. The apparatus
was designed to furnish a more rapid method of testing
mortar beams in flexure and which could be employed
in laboratories not equipped with a universal testing
machine of sufficient sensitivity to test such beams.
VALVE
HANDLE
RAI
a
SHOT VALVE
FOLLOWER
RUBBER
CUSHION
SPECIMEN—$o
BEAM CLAMP
HOSE
CLAMP. a
4
eo
ei ne
» EXTENSION BEAM
Wwe
APPARATUS FOR TESTING BEAMS AS CANTILEVERS
The apparatus consists of a clamping device to hold
the beam securely and an extension arm which fastens
on the end of the beam and transmits the load as shown
in Figure 1. The beam may be loaded by any means
that is at hand. In the bureau laboratory, No. 12
lead drop shot are used to apply the load. The shot
are fed from a reservoir fastened to the wall, and
equipped with a quick-action valve which opens com-
pletely by moving the control handle through a 60° are.
The two thumbscrews shown in the clamping device
bear on a steel plate three-eighth inch thick, which
rests on the specimen. ‘The beam is tested in the same
position that it is molded, 1. e., with the troweled surface
up. Slight irregularities in the troweled surface have
70
prevented an even distribution of stress over the surface
exposed to restraint, and have consequently given poor
breaks with an accompanying wide variation in test
results. To overcome this, a piece of sheet rubber
one-eighth inch thick is placed between the bearing
plate and the specimen. ‘This has given very good
results.
The test specimens, 2 by 3 by 12 inch beams, are made
in steel molds. The use of such molds, with carefully
machined surfaces, is considered highly ‘advisable.
Computations of the modulus of rupture are made
using the formula
Mc
ae
where
S=modulus of rupture, in pounds per square inch,
A M=bending moment in inch-pounds, = W,l,+ Wel,
where
W,=test load, in pounds
l,=distance of load from support=18.12 inches,
We=weight of arm,
l,—= distance of center of gravity of arm from support,
c=distance of extreme fiber from neutral axis, or 1%
inches,
I=moment of inertia of cross section of beam about its
central horizontal axis.
Substituting the particular constants which applied
for these tests, and neglecting the weight of the over-
hanging beam we have,
S=12.4+6.04W, (pounds per square inch)
Neglecting the weight of the overhanging section
of the beam is in accordance with the usual practice in
testing beams for flexure under center loading.
To demonstrate the suitability of this apparatus for
testing beams, four series of beams were prepared for
comparative tests in the cantilever apparatus and in a
universal testing machine under center loading. Each
series included five or six 18-inch beams for test under
center loading, and an equal number of 12-inch beams
for test in the cantilever apparatus. Series B, C, and
D were made of a 1 :3 mix and series A of a 1 :2 mix
using Potomac River sand in all series. Series A was
tested at an age of 14 days, series B at 28 days, and
series C and D at 7 days.
The various series were made in the laboratory as
time permitted. Because of the small number of
molds available, no effort was made to tie the four
series together. In series A, each specimen was made
from a separate batch, the 18-inch beams being made
first. Inspection of the test results of this series indi-
cates that the water-cement ratio may not have been
exactly constant for the two sizes of beams. When
tested as cantilevers, the halves of the original 18-inch
beams check the center loading tests, whereas the
12-inch beams tested as cantilevers show somewhat
lower values. To guard against this, and to furnish a
better comparison between the two methods of testing,
in series B, C, and D each 18-inch and the corresponding
12-inch beam were molded simultaneously from the
same batch.
The 18-inch beams were tested in an Olsen universal
testing machine of 40,000 pounds capacity. A small
beam rider was used which decreased the machine
ratio by 10, and permitted accurate reading of the
applied load to the pound. <A span of 15 inches was
used and the beams were mounted on rockers in accord-
ance with approved practice. The rate of applica-
tion of the load was such that the modulus of rupture
developed at an average rate of about 100 pounds per
Square inch per minute. The broken halves were
then tested in the cantilever apparatus to serve as a
check. ‘These last tests are shown in Tables 3 and 4.
The 12-inch beams were tested in the cantilever
apparatus, applying the load at a rate of 15 pounds
per minute. This produced a stress increasing at the
rate of 102 pounds per square inch per minute. Two
breaks were made on each beam. The beam was in-
serted in the clamping device and the extension arm
hung on the free end of the beam. The beam was
then so adjusted that the base of the extension arm
was one-sixteenth of an inch from the clamping device.
This space is the minimum sufficient to permit flexure
without binding. The beam was then firmly fastened
and loaded to failure. The breaking load was weighed
to the nearest tenth of a pound.
Tables 1 to 3 give the breaking load and computed
moduli of rupture for each individual specimen.
Table 4 presents a summation of the strengths,
together with the mean variation from the average
for each series.
There appears to be little variation between the
test results obtained by the two methods of testing.
The strengths obtained are essentially the same and
the variation found between individual breaks aver-
ages the same in each case. It may be said that the
testing of mortar beams can be performed as accu-
rately with this cantilever device as by the customary
method in the universal machine.
The retests of the 18-inch beams are of interest
since they demonstrate that specimens broken under
center loading may be checked by test of the two
halves in the cantilever apparatus. In a series of
tests extending over several periods of testing, one
18-inch beam could be tested at three different ages,
the first test being by the center-loading method, and
TABLE 1.—Results of tests under center loading in universal
machine using 15-inch span
Series A, mix 1:2, || Series B, mix 1:3, Series C, mix 1:3, Series D, mix 1:3,
age 14 days age 28 days age 7 days age 7 days
Break- | Modulus |} ¢ Modulus a Modulus . Modulus
ing | ofrup- | 2 Aer te ofrup- ||P pane of rup- ei of rup-
load ture ture ture | ture
Lbs. per Lbs. per | | Lbs. per Lbs. per
Pounds| sq. in. Pounds | sqg.in Pounds | sq.in. Pounds | 8q. in.
487 608 415 519 320 406 308 385
435 544 420 | 525 316 395 363 454
416 520 420 525 315 394 345 431
396 495 379 474 . 320 400 332 415
438 ei las na lacks bate a 383 476 318 398
Average... 543 Average... 511 Average.... 413 Average.... 417
PUBLIC ROADS
ff
TABLE 2.—Results of tests of 12-inch beams in cantilever apparatus
}|
Series A, mix 1:2, || Series B, mix 1:3, | Series C, mix 1:3, | Series D, mix 1:3,
age 14 days | age 28 days | age 7 days age 7 days
ee ee jt. » ;
Break- |Modulus |, Breaking | Modulus |; Breaking Modulus | Breaking Modulus |
ing | ofrup- | load of rup- | load ofrup- | ad ofrup- |
load ture || ing iy ee ture “4. iP tars
| Lbs. per | Lbs. per | Lbs. per | | Lbs. per
Pounds; sq.in. | Pounds sq.in. || Pounds sq. in, Pounds | sq. in,
85.0 | 526 86. 3 533 | 69.5 432 Ta | 447
82.0 508 84.5 522 74.0 459 69.5 432
86.5 535 76. 7 475 63. 5 396 67.0 417
88. 5 547 84.0 519 63:5 | 396 68. 5 426
77.5 481 85. 0 525 63. 5 396 ‘| 66.0 411
85. 0 526 81.3 503 | 569.2 370 Ta;.2 455
79. 0 490 79.0 489 66. 0 411 61.0 381
87.0 538 81.3 503 || 68.5 | 426 58. 5 366
78.5 487 77.5 480 64. 5 402 76.0 472
78. 0 S| eee ae t cmetha st | 64.0 | 399 64.0 399
90. 0 Ate | Ree ho ee at Se fill pcaarce nies teen
82.0 508 Se 5 isan wathted lt catered ace tell Os fx and meen lea test crt ies ene ws crake Cie ote eat
| | rast
Average... 516 | Average.... 505 || Average.... 409 Average.... 421
| |
TABLE 3.—Results of tests of 9-inch beams in cantilever apparatus
|
Series A, mix 1:2, } Series B, mix 1:3, Series C, mix 1:3, Series D, mix 1:3, |
age 14 days | age 28 days age 7 days age 7 days
a ee | a = eld
iI |
Break- | Modulus | | Modulus || -ing | Modulus -,| Modulus |
ing | ofrup- |B septa ofrup- | ae of rup- senegal ofrup- |
load ture ture | ture | ture
Lbs. per | Lbs. per Lbs. per | Lbs. per
Pounds| sq. in. Pounds sq.in. || Pounds | sq. in, Pounds | sq. in.
84,0 518 82. 0 507 62. 5 389 «|| «=—63.0 | 393
87.0 538 88. 3 545 62. § 389 72.0 | 447
87.5 541 83. 3 515 74.0 459 71.0 441
91.0 562 | 71.3 442 65. 0 405 70.0 435
88.5 547 | Si.o)=4 539 61.5 384 72.0 447
89. 0 550 89. 0 | 549 65: 2 406 63. 5 396
100. 0 616 83.7 | 518 || 658.0 363 73.0 453
80. 0 496 81.3 | 503 || 58.0 363 66.0 411
96. 5 595 | 76. 5 474 72. § 450 69. 0 429
94. 0 J al || ener We ROY | RT ef 420 71.5 444 |
; | | : OMe |S ae
Average... 553 | Average.... 510 Average.... 403 Average.... 430
TABLE 4.—Average results of tests of each series and mean deviation
from average
Cantilever, 12-inch | Cantilever, 9-inch
Center loading Kaatne heaiis
Series Average; Mean | Average| Mean | Average! Mean
modulus |deviation| modulus |deviation’ modulus |deviation
of from of from of from
rupture | average | rupture | average | rupture | average
| Lbs. per Lbs. per | Lbs. per
sq. in. Per cent Sq. in. Per cent sq. in. Per cen
fee Ape 2 ee Bee. 543 5. 2 516 5. 2 Die 4.7
ae a ee = 511 3.0 505 3.4 510 5.0
Civcn in a, & dee oe eons 413 6.1 409 4.6 403 6.2
pw See Ee eet 417 5.0 421 6. 2 430 4.2
EOE CRE tats ela] HA Seas oc gg eee eee LY ee eee 5.0
the other two by cantilever action. Such a method
would furnish a more accurate index of the effect of
age than could be obtained with three different speci-
mens with the accompanying uncertainty of identical
preparation.
Working drawings of the cantilever apparatus may
be obtained upon request.
Loe]
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i LCOk SAXV.L ANIIOSVD
ROAD PUBLICATIONS OF BUREAU OF PUBLIC ROADS
Applicants are urgently requested to ask only for those publications in
which they are particularly interested. The Department can not under-
take to supply complete sets nor to send free more than one copy of any
publication to any one person. The editions of some of the publications
are necessarily limited, and when the Department’s free supply is
exhausted and no funds are available for procuring additional copies,
applicants are referred to the Superintendent of Documents, Govern-
ment Printing Office, this city, who has them for sale at a nominal price,
under the law of January 12, 1895. Those publications in this list. the
Department supply of which is exhausted, can only be secured by pur-
chase from the Superintendent of Documents, who is not authorized
to furnish publications free.
ANNUAL REPORTS
Report of the Chief of the Bureau of Public Roads, 1924.
Report of the Chief of the Bureau of Public Roads, 1925.
Report of the Chief of the Bureau of Public Roads, 1927.
DEPARTMENT BULLETINS
No. 105D. Progress Report of Experiments in Dust Prevention
and Road Preservation, 1913.
*136D. Highway Bonds. 20c.
220D. Road Models.
257D. Progress Report of Experiments in Dust Prevention
and Road Preservation, 1914.
*314D. Methods for the Examination of Bituminous Road
Materials. 10c.
*347D. Methods for the Determination of the Physical
Properties of Road-Building Rock. 10c.
*370D. The Results of Physical Tests of Road-Building
Rock. 15c.
386D. Public Road Mileage and Revenues in the Middle
Atlantic States, 1914.
387D. Public Road Mileage and Revenues in the Southern
States, 1914.
388D. Public Road Mileage and Revenues in the New
England States, 1914.
390D. Public Road Mileage and Revenues in the United
States, 1914. A Summary.
407D. Progress Reports of Experiments in Dust Prevention
and Road Preservation, 1915.
463D. Earth, sand-clay and gravel.
*532D. The Expansion and Contraction of Concrete and
Concrete Roads. 10e.
*537D. The Results of Physical Tests of Road-Building
Rock in 1916, Including all Compression Tests.
oC.
*583D. Reports on Experimental Convict Road Camp,
Fulton County, Ga. 25c.
*660D. Highway Cost Keeping. 10c.
*670D. The Results of Physical Tests of Road-Building
Rock in 1916 and 1917. 5c.
*691D. Typical Specifications for Bituminous Road Mate-
rials. 10c.
*724D. Drainage Methods and Foundations for County
Roads. 20c.
*1077D. Portland Cement Concrete Roads. 15ce.
1259D. Standard Specifications for Steel Highway Bridges,
adopted by the American Association of State
Highway Officials and approved by the Secretary
of Agriculture for use in connection with Federal-
aid road work.
1279D. Rural Highway Mileage, Income, and Expendi-
tures, 1921 and 1922.
DEPARTMENT BULLETINS—Continued
No. 1486D. Highway Bridge Location.
DEPARTMENT CIRCULARS
No. 94C. T. N. T. as a Blasting Explosive.
331C. Standard Specifications for Corrugated Metal Pipe
Culverts.
TECHNICAL BULLETIN
No. 55. Highway Bridge Surveys.
MISCELLANEOUS CIRCULARS
No. 62M. Standards Governing Plans, Specifications, Con-
tract Forms, and Estimates for Federal Aid
Highway Projects.
93M. Direct Production Costs of Broken Stone.
*105M. Federal Legislation Providing for Federal Aid in
Highway Construction and the Construction of
National Forest Roads and Trails. 5c.
_ FARMERS’ BULLETINS
No. *338F. Macadam Roads. — 5e.
*505F. Benefits of Improved Roads. | 5e.
SEPARATE REPRINTS FROM THE YEARBOOK
No. *739Y. Federal Aid to Highways, 1917. 5c.
*849Y. Roads. 5c.
914Y. Highways and Highway Transportation.
937Y. Miscellaneous Agricultural Statistics.
TRANSPORTATION SURVEY REPORTS
Report of a Survey of Transportation on the State Highway
System of Connecticut.
Report of a Survey of Transportation on the State Highway
System of Ohio.
Report of a Survey of Transportation on the State Highways of
Vermont.
Report of a Survey of Transportation on the State Highways of
New Hampshire.
REPRINTS FROM THE JOURNAL OF AGRICULTURAL RESEARCH
Vol. 5, No. 17, D- 2. Effect of Controllable Variables upon
the Penetration Test for Asphalts and
Asphalt Cements.
3. Relation Between Properties of Hard-
ness and Toughness of Road-Build-
ing Rock.
5, No. 24, D- 6. A New Penetration Needle for Use in
Testing Bituminous Materials.
8. Tests of Three Large-Sized Reinforced-
Concrete Slabs Under Concentrated
Loading.
Vol. 11, No. 10, D-15. Tests of a Large-Sized Reinforced-Con-
crete Slab Subjected to Eccentric
Concentrated Loads.
Vol. 5, No. 19, D-
Vol.
Vol.. 6, No. 6, D-
* Department supply exhausted.
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