Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

rae
Pat Con =~

ee

UNITED STATES DEPARTMENT OF AGRICULTURE

4 BULLETIN No. 1077 MA

Washington, D. C. Vv October 21, 1922

PORTLAND CEMENT CONCRETE ROADS.

By JAMES T. VosHELL, District Engineer, and R. E. Toms, Senior Highway
Fingineer, Bureau of Public Roads.

CONTENTS.
Page. Page.

TATMVERELOY OID KO| IT U0Y 0 Veep t= ee ees 1 | Constsuction—Continued.

Materials used. in concrete roads____ 3 Preparation of the subgrade____ 29
Waemenb= tet sere Pale see tog 3 BE TTS pe ee ie eg re ee 30
Hineiacvoresa terms (sess fe 3 Handling and hauling materials_ 3
Conrsesacerevate = a 4 Mixiney and placnc= sss 40
WV aii einer ree veto NR ah i 5 Finishing the surface __--_____ 42
HeindOrCeMeN ta mes oe ee 6 Protecting and curing the con-

| EA AG) OXON PLEO NOTH 6 Fc ee ieee Ee ES oe ea Bis 6 CLEt Gs aes a2 ee Ne eee 46

Quantities of materials required____ 10 Placing conerete in freezing

JOSS Cth asc ae es ae iy ee 10 Wea theme: {set ie ise eee eee AT
Widthe of pamement= == 2.20. 11 | Organization and equipment _______ AT
Thickness of pavement________ 197) Capital requircd{_— sae a 55
Grownrof- pavement... | 14 | Cost of concrete pavements________ 5D
Superelevation of curves_______ 5p eViaintenancci = =... ee eee 58
Wadenins? onicurves——— 16 | Resurfacing old concrete pavements_ 59
a \Oniah Ree Shane ee ee S157 | eANSED TN CU ect SS oO ies ee 61
Steel reinforcement _—__ = = 23 A. Quantities of materials re-
Shoulders and ditches_________ 24 Quinéd 25425 03 61
Gurbsvand cutters. = =) Sa 25 B. Tables for determining the
Bituminous surface treatment__ 25 size of pump required for
lie a CLOSS-SCCHON: oe. a 27 delivering water == _---_—_— 63

WOMNERUCHION fe 8 are ee 27 C. Cost of Federal-aid concrete
‘(Gae U Tis Pe eo ee See, eens 27 pavement sso 22 et ee 64
TOTES Oa ere: ae eee Set ya a ere eater 7.

INTRODUCTION.

|
The purpose of this bulletin is to supply reliable information on
the subject of concrete pavements for the use of highway engineers
and others interested in the improvement of public roads. The meth-
ods of construction described are believed to represent the best prac-
tice at this time; but, as experience and research are continually sug-
gesting improvements, those who have charge of concrete-road con-
101130°—22——1

==

2 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

struction should be careful to keep themselves informed regarding
results obtained by others engaged in similar work, and by laboratory
experiments.

The earliest concrete pavement in the United States of which there
is reliable record was constructed at Bellefontaine, Ohio, in 1893 and
1894. This pavement, which contains 4,400 square yards, was con-
structed in two courses and in squares similar to those employed in
concrete-sidewalk construction. Prior to 1909 the total area of con-
crete pavements was comparatively small, and in most cases these
pavements were frankly regarded as experiments. During 1909 the
road officials of several communities concluded that the results already
obtained were sufficiently encouraging to warrant them in undertak-
ing the construction of concrete pavements on a larger scale, and since
that time a large mileage has been completed. Wayne County, Mich.,
was one of the first communities to adopt this form of construction,
and at present probably has a greater mileage of roads paved with
concrete than any other county in the United States.

The majority of the concrete pavements which have been construct-
ed have proved entirely satisfactory where traffic conditions were not
unduly severe, and their use has increased rapidly. This is evidenced
by the following tabulation, showing the approximate number of
square yards of such pavements that have been placed under con-
tract in the United States each year beginning with 1909, and the

ER Oe ll RN etal Rt Set PGS RECESS Fe

a7 CE eit DWE Peiak ;

total constructed prior to 1909: 7
Concrete pavement constructed or under contract in the United States.

Year. Roads. Streets. Alleys. | Totals.

Sq. Yds. SQa ase Sq. Yds. Sq. Yds.
rtOr tO 909s ict fre aie eee 34, 061 444, 864 112, 491 591, 416
ILGXO Sia ae an PEE aseee Soa ee 32, 626 325, 158 86, 825 444, 609
TIO) Re ae aya nee 151, 148 682, 637 107, 874 941, 659
TOTTI Sen eR Ne Hird 291,077 | 1,011, 440 136, 674 1, 439,191
[CILLA er Rae SAE ee PSs SS 1, 869,486 | 3,326, 029 185, 703 5, 381, 218
QUNG SA 5s cane 2. ee eae a ee 3, 009, 185 | 3,946, 219 308, 365 7, 593, 769
C1 Sa eae ani pea gS oN 10, 608,421 | 4, 830, 604 300,138 | 15,739, 163
GH eae a te ole a eee eae 12,050, 909 | 5, 933, 879 612,921 | 18,575, 709
OMG ae Cee es SOR bot sei 15, 906, 801 | 7,395, 975 880,179 | 24,182, 955
Ofek ove eom 2 Uae. Nemes 15, 333, 087 | 5,238,062 | 1,200,030 | 21,771,179
GWG eY Seek oe eh ey ep ee 12, 990, 519 | 3,295, 817 585, 948 | 16,872, 284
NON Seok epatis Bete tke LR oe 41, 335, 342 | 11,086,419 | 1,038,173 | 53, 459, 934
OD ec oa’ S ade tac pe ere 29, 326, 689 | 8, 814, 782 907,164 | 39, 048, 635
Total to Jan. 1, 1921. . - ./143, 269, 351 | 56,331,885 | 6,465,485 | 206, 063, 721

The principal advantages which concrete pavements possess may
be briefly stated and commented upon as follows:
1. As far as can be judged, they are durable under ordinary sub-

urban and rural traffic conditions.

PORTLAND CEMENT CONCRETE ROADS. 3

2. They present a smooth, even surface, which offers very little
resistance to traffic. i

3. They are practically dustless and may be easily cleaned.

4. They may be maintained at comparatively small cost.

5. They may be made to serve as a base for some other type of
surface when resurfacing becomes necessary.

The principal disadvantages are:

1. They are somewhat noisy under steel-tired traffic.

2. They are subject to cracking, and wherever a crack develops it
must be given frequent attention in order to prevent deterioration of
the pavement.

3. On account of the sharp line of separation between the pave-
ment and the shoulders and the marked difference in hardness, an
abrupt and dangerous depression is sometimes formed at the edge of
the pavement which reduces the effective width of the roadway.

A finished concrete road is shown in Figure 1, Plate X.

MATERIALS USED IN CONCRETE ROADS.

Concrete consists of a mixture of water, cement, sand, and gravel
or stone or other similar materials. It is customary to refer to the
sand as the fine aggregate, and to the gravel or stone as the coarse
ageregate. Durable, clean, well-graded aggregates are absolutely
essential to the success of a concrete pavement. Mixed aggregates,
such as bank-run gravel or crusher-run stone, should not be used
except under rigid laboratory control. For a successful concrete
pavement, each of the different aggregates should be properly graded
and kept clean and separate until proportioned to place in the mixer.

CEMENT.

Portland cement of a character satisfactory for use in pavement
construction is at present manufactured in nearly every section of
the country. The product of all cement plants is not always en-
tirely uniform and of equal excellence, and even if it were uniform
immediately after manufacture this condition might easily be
changed by age or exposure. These facts make it imperative that
cement for use in concrete pavements be subjected to very rigid tests.
It should meet the requirements of the specification for Portland
cement contained in Circular 33 of the United States Bureau of
Standards and also issued by the American Society for Testing
Materials, and accepted generally as the standard specification.

FINE AGGREGATE.

Sand is almost universally used as a fine aggregate for concrete
pavements. In exceptional cases stone screenings have been used,
but the use of screenings is not recommended, as the presence of dust

4 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

in the screenings makes the proper mixing rather difficult and re-
duces the strength of the concrete, unless the time of mixing is con-
siderably increased. Sand for use in concrete pavements should be
selected with especial care. The strength of the mortar depends
largely upon the quality of the sand and a strong mortar is impera-
tive if the best results are to be obtained. Preference should be given
to sand composed of a mixture of coarse and fine grains, with the
coarse grains predominating, though sand consisting entirely of
coarse grains is preferable to that in which the fine grains predom-
inate. Sand which contains more than 3 per cent of foreign mate-
rials, such as clay or silt, or the grains of which are coated with clay
or other objectionable material, should not be used. Sand which
contains even a small percentage of organic impurities is unsuitable
because the presence of such impurities seriously affects the strength
of the concrete. The presence of these impurities can not be de-
tected by the eye but may be readily detected by means of the re-
cently developed colorimetric test, which is suitable for use in the
field. In order that the mortar may develop the necessary strength,
it is usually specified that mortar made from the sand proposed for
use in the concrete pavement shall develop a tensile or compressive
strength equal to that developed by mortar made of the same cement
and standard Ottawa sand when mixed in the same proportions and
tested at the same age.

It is generally specified that fine aggregate for concrete pavements
shall consist of particles smaller than one-quarter inch in size. A
well graded fine aggregate should meet the following requirements:

Per cent.
Passing a. 4-ineh SCTeen.. S650) 2 Sake ees oe a ee er 100
Passing a 4-inch screen and retained on a standard No. 10
SIO@V Gs 2 02 Soe oe ae ig CS a Be es, nae N—-25
Passing a standard No. 10 sieve and retained on a standard
NOx D0 SICViCL 2 = oak at x eee Seas Pia ae ae ae 50-90
Passing a standard No. 100 sieve, not more than __________ 10
Weight removed by elutriation, not more than______________ 3

COARSE AGGREGATE.

Coarse aggregate for concrete pavements usually consists of gravel
or crushed stone, although occasionally blast-furnace slag is used.
The choice between these materials depends largely upon local condi-
tions. Satisfactory concrete pavements have been constructed with
each, but so far as cracks are concerned limestone appears to have
made a better record than gravel or any other variety of stone which
has been used to any considerable extent.

1¥or a description of this test see U. S. Department of Agriculture Bulletin 949, Stand-
ard and Tentative Methods of Sampling and Testing Highway Materials.

——— a ee

PORTLAND CEMENT CONCRETE ROADS. 5

The coarse aggregate, whether crushed stone, gravel, or slag, should
possess at least as great resistance to wear as the mortar which fills
the voids of the aggregate. Any sound stone or gravel, moderately
hard and tough, will meet this requirement, but in general the harder
-and tougher the coarse aggregate, the greater will be the resistance
to wear offered by the concrete. The best available stone should
always be used.

The difficulties experienced in securing coarse aggregate of satis-
factory quality are frequently caused by a lack of proper facilities
for preparing the natural materials available. Very few gravel pits
furnish a gravel suitable for use in concrete pavements without wash-
ing; and properly equipped washing plants are both difficult and ex-
pensive to construct. On the other hand, a great many stone quarries
contain pockets of clay or inferior stone which should not be per-
mitted in the aggregate, and it is sometimes very difficult to remove
the objectionable materials while the stone is being crushed and
screened. It is also frequently difficult to screen out the dust formed
in crushing some varieties of stone. These difficulties can be largely
overcome by obtaining the coarse aggregate from commercial sources
that are properly equipped to supply clean, well-graded ageregates.

The coarse aggregate should be free from shale, slate, coal, ocher,
or other materials which easily disintegrate and should meet the
following requirements:

Stone: French coefficient of wear, not less than 7.

Gravel: When subjected to the abrasion test as described in Bulletin 555,
United States Department of Agriculture, page 30, the loss by abrasion should
not be more than 12 per cent.

Slag: The slag should be an approved blast-furnace product, weighing not
less than 80 pounds per cubic foot.

A well-graded coarse aggregate is necessary in order that the per-
centage of voids may be as small as practicable. The grading of the
coarse aggregate is usually accomplished by specifying the various
percentages of material which will pass or be retained on screens
with circular openings of different sizes. The maximum size of
aggregate used varies according to the practice of various States and
the character of materials available. The maximum size most com-
monly specified is 24 inches. A well-graded coarse aggregate should
meet the following requirements:

Per cent.
fei Sonneee AITChin SCLCCH = oe ee a a Ue es Ee 100
Passing a 2-inch screen and retained on a 1-inch screen____ 25-60
Bassine 24-inch sereen; not) more: thant ——_V=-_- = 22 -----2-_- 10

WATER.

Water used in mixing concrete should be practically free from oil,
acid, alkali, or organic matter and reasonably clear. Brackish water

6 BULLETIN 1077,.U. S. DEPARTMENT OF AGRICULTURE.

and water carrying sewage or manufacturing wastes should not be
used until tests have shown that it will not impair the strength of
the concrete. For a description of a test to determine the quality cf
water, see United States Department of Agriculture Bulletin 949.

REINFORCEMENT.

Wire mesh, expanded metal, or steel rods may be used to reinforce
the pavement. In any case the reinforcement should be reasonably
free from rust, or other coatings, and should be so handled prior to
use that it will not be coated with mud or clay when placed in the
pavement.

PROPORTIONING.

The physical characteristics of the concrete are determined not
cnly by the quality of the several materials which enter into it, but
also, and perhaps to a greater degree, by the proportions in which the
materials are mixed, especially by the amount of water used. A
number of theories are offered concerning the proportions required
to produce strong and economical concrete. All are based on experi-
mental data, but at present no particular one is generally accepted,
and a great deal of investigation is being carried on in the attempt to
evolve a theory which will be generally acceptable.

The theory most generally accepted in the past is called the maxi- |

mum density theory? and is based on the assumption that with a
given amount of cement the strongest concrete is secured with aggre-
gates graded and mixed so as to have the least amount of voids,
without an excess of fine material. It has been found from a large
number of tests that the average ratio of fine to coarse ageregate
for maximum density is approximately 1 to 2, a fact which accounts
for the rule-of-thumb mixes, as, for example, the 1:2:4 mix, which
means 1 part of cement to 2 parts of sand and 4 parts of coarse ag-
geregate. If greater strength is required a 1: 14:3 mix is used; if less
strength is needed the proportions 1: 24:5 or 1:3:6 may be adopted,
but the practice is to maintain the ratio of 1 to 2 between the volumes
of the two aggregates. A large amount of concrete has been mixed
according to these rules, but objection is made to them on the ground
that the particular aggregates used may differ materially from the
average. Good aggregate and cement mixed according to the maxi-
mum density theory with a proper amount of water will produce a
good concrete, but the theory itself does not take into account the
amount of water to be used. Lately the amount of water has been
found to exert a most important influence on the strength of the
concrete. Iixcess, it has been found, invariably brings about a de-
crease in strength.

2“ Concrete, Plain and Reinforced,” by Taylor and Thompson.
>

PORTLAND CEMENT CONCRETE ROADS. 74

The theory * has recently been advanced that the strength of the
concrete depends entirely on the ratio of the amount of water to the
amount of cement so long as the mix is workable. According to this
theory variation in the grading of the aggregates affects the strength
of the concrete made with a given amount of cement merely because
it affects the amount of water that is required to produce a work-
able consistency. If the proportion of cement be varied to main-
tain a constant ratio of cement to water, any reasonable grading of
aggregates can be made to yield a concrete of approximately any
desired strength. An arbitrary quantity known as the “ fineness
modulus” is determined by sieve analysis of the aggregates and this
quantity together with the maximum size of the aggregate determines
the amount of cement to be used. The strength of the concrete made
from the cement and aggregate in the determined proportions will
depend upon the amount of water used. Tables and charts based
upon experimental] data supply the means for the practical applica-
tion of the theory.

Another theory * is based on the assumption that to produce con-
crete of a given strength a certain amount of cement is required for
each unit of surface area of the aggregate, taking into account the
amount of water used in mixing. The particles are assumed to be
spheres, and tables have been worked out from which the surface
area of a given amount of the aggregate can be determined from the
sieve analysis. |

It is worthy of note that each of these theories tends to the use
of well-graded aggregates and rich mixes where strong concrete is de-
sired. They have all been evolved in the attempt to design concrete
of high strength, which is needed in pavement concrete to enable
the pavement to resist temperature and impact stresses without
excessive cracking. That concrete high in compressive strength is
also highly resistant to abrasion is the conclusion drawn from tests
conducted by Prof. Duff A. Abrams, Lewis Institute, Chicago. It
was observed in these tests that the resistance to abrasion fell oif
sharply when the compressive strength dropped below 3,000 pounds
per square inch. The tests conducted by the Bureau of Public Roads
do not support this conclusion, but indicate, rather, that the amount
of wear of the concrete depends upon the character of the coarse
ageregate. It should be noted that in the tests conducted by Pro-
fessor Abrams only two kinds of coarse aggregate were used. For
any given coarse aggregate, however, it is likely that increase in
compressive strength will result in corresponding decrease in wear.
From experience it has been found that pavement concrete should
be proportioned to have a compressive strength of not less than 3,000

3 Bulletin 1, Structural Materials Research Laboratory, Lewis Institute, Chicago.
4 Proceedings of the A. S, T. M. for 1918, pt. 2, p. 236.

8 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

pounds per square inch. Pavements composed of concrete of less
strength have generally proved unsatisfactory.

In practice it is generally not feasible to follow strictly any of
the theories in the proportioning of the materials. The aggregates
must usually be obtained from commercial sources and the specified
grading of these aggregates must be such that they can be supplied
without excessive expense or decreased output. The maximum size
usually specified ranges from 14 to 24} inches. When the 24-inch
size is permitted it is usually provided that 90 to 95 per cent of the
aggregate shall pass a 2-inch circular opening. Tor sand graded as
described on page 4 and a coarse aggregate, well graded from + inch
to 14 inches, the proper proportions for concrete pavements would
be 1 part of cement to 2 parts of fine aggregate to 3 parts of coarse
aggregate. For coarse aggregate from + inch to 24 inches in size,
a proportion of 1:2:34 or even 1:2:4 may be used provided there
is sufficient mortar to finish the concrete properly. These propor-
tions may have to be altered slightly, but for good commercial ag-
gregate graded as described on page 5 the proportions given will
prove satisfactory. Where it is not possible to obtain commercially
graded aggregates of the sizes mentioned, different proportions of
ageregate should be used. The following table,> which gives a
large number of proportions designed to produce concrete of ap-
proximately 3,000 pounds compressive strength at 28 days when
mixed with the water necessary to give a workable consistency,
indicates the great variety of combinations that can be used.

Abrains’s table of proportions and quantities for one cubic yard of concrete.

[Based upon laboratory investigations, using approved materials, compressive strength, 28 days, with
workable plasticity, 6 by 12-inch cylinders, 3,000 pounds per square inch.} .

Cement in barrels, aggregates in cubic yards.

Fine aggregates, screen openings per inch.

Coarse aggregates.

0-28 0-14 0-8 0-4 0-2 in.
Ee { + - ne ae) +
qj o q cS) q o q ro) =| ro)
Size, inches. SW Sle BSS eels | als Slee coeale etal see [ieee
Be Ps Bo go eB) los ok | Gupis ee ainee es
oO cy .@) oO ei iS) 1S) Py 2) i) ic ie) .@) Ry Oo
No. 4 screen to 3:
Proportions........] 1 1.3|2.4] 1 ViG5|) 2e4at a Listes |p yey || al 97251 Del PD, sh Let 2k Vea
Quantities. .......-. 1.96} .37} .69) 1.85 +H 66) 1.82 48 62) 1.75 52 9} 1.79 72| .40
No. 4 screen to 1: |
Proportions........| 1 LOH PQei hel 1.6,|. 2.6) 1 HS p enon et 2 2.5 | 1 2.6} 1.8
CHAN TIiNES so. aaeiae 15 90| wets0|s eG] chev ln | Sele OSlmboiel neeor Obl eG, 50} .62) 1.72) .66] .46
No. 4 screen to 14:
Proportions........| 1 Leu ee sad EG Sea a 1a mete boul 22 Qa oO ut 2.4 |} -2.4
-Quantities.......-. 1,82) .32| . 84) 1.68) .40) . 79) 1.63) .41) .75) 1,61 47 72) 162i, Sv eid
No. 4 screen to 2: |
Proportions......-.] 1 1.2) 3.5] 1 LLM) (Seo; |, L5G) |eSavill 1.9} 3.6.) 1 2.2 | 3.1
Quantities......... 1.75; .31} .90) 1.68) .36 85] 1.55) .36 85) 1.52) .43 81] 1.53} .50} .70
®°'Table prepared by A. N. Johnson, based on results of investigations by Brot 7DwAe

Abrams, Structural Materials Research Laboratory, Lewis Institute, Chicago, Ill.

PORTLAND CEMENT CONCRETE ROADS. 9

Abrams’s table of proportions and quantities for one cubic yard of concrete—
Continued,

Fine aggregates, screen openings per inch.

Coarse aggregates.

0-28 0-14 0-8 0-4 0-2 in.
ee + ~~ + ~ ;
ssh APSA es ROS UN SIREN en Va f= na at
Size, inches. Hi elsi8i/sisei8/siaei8@/8ie/8l]els
Sea meee Op | Oma ie OT ne ee eA Red Fee
| No.4 screen to 24:
IPTOpPOLWONS-24..~- = 1 A Tey ll es okE al W4aos oe TSG ee KO eal 1.8) 4.0) | 1 PAU REG

Quantities. ........ 1.72} .28 .97) 1.58) .33) .91) 1.51) .35] .89) 1.49] .40] . 88! 1.50} .46] .78
No.4 screen to 3:

Proportions........| 1 He oe! ot 1.4/4.1] 1 1.5] 4.1} 1 Mest fe 4d | al 2.0 | 3.7
- Quantities Benn Serie 1.69} .28) .97) 1.58) .33) .97] 1.49) .33] .90) 1.49} .37) .90) 1.49] .44) .81

03:
a Proportions. een (ie | Sey) ss) 1) a US? lee58) |p al TON 28 li PP MP2, Dk 2.8 | 1.4
4 Baavatlies > ae as EOC EE OdanOt|laSo|nee 40! meGal te Sain oll Oil. Odie od eco] ovals sod
Ztol

Proportions. Eee Sac 256n) 17 -f 2.65)-1 1 Oue23 On |e Daan Aa te GAME || Wey
at Bian ties Ree Sena 1,90) .36) 274) 1.77) .44) 2.68) 1.72) .48) 164) 1.67) .54) 259) 1.72] .68) .43

ol

Proportions........ 1 Fito) |PosO.| au US 7f BRU) pal 19) | SHON EL 2} 2. 9h 256 2.2
~ Quantities... 22... .. 1,82) .35) .80) 1.68) .43| .75] 1.63) .46) .73] 1.61) .50) .68) 1.62) .63) .53
3 to 2:

3 Proportions........ 1 Hoe} {| She) ira igiios aa el They 844) [Pal 2.0] 3.4] 1 2.4 | 2.9
st oe a 8 Bs 8 1.75) .34) .86) 1.63) .41) .83) 1.55) .42) .80) 1.52) .45) .77| 1.53) .62) .66
6

Proportions........| 1 1683 lish relia Tp BH eal ee eco ule 2.0 |335 8) 1 2.3 | 3253
ee ppentities Seer se 1.72) .33) .95) 1.58) .37| .87| 1.51) .37) .87| 1.49) .44) .84) 1.50! .51] .74
2 to 3:

; Proportions........| 1 1.2) 3.8] 1 ia) CeO eal lg eA Ole 1.9} 4.0/1 A159) |) Be
a Quantities Eee a ae 1.68} .30) .95) 1.58) .37) .91) 1.49} .37| .88) 1.49) .42) .88) 1.49) .48) .77
3 tO f:

Proportions........ 1 Leper 2i3 el 1.9} 2. 210 BR OR a PRS || Fah] A 2:\8 1 1.3
bs Quantities. = 22 -: SOG es 44 Ee OU ple Soln roa! ae OL ee 82s 56) 259 t. 75i 591) 304) Te 7G) 75 | 334:
$to 1:

Proportions... 1 611.5) 2.5)1 OME Za oll 2.1 | 2.4 | 1 203, 2.4.) 1 2.8 | 1.6
re Quantities......... COO S42 Ol aleiaien OO) sOGite (20). bole. Ol) DG) Soci. o9|) lov2i zie beak
5 to 13: |
: Proportions........] 1 WAG 258 ORES) tia 2oL' 2.9) 1 2: 2a\e2s Sail Pe Th | Pal
é Quantities! ©... =. IES2 ecole coll LOS) 347) fol oleOa|) voll.) s69h 1 6L 521) (66) 16215 .65|aoL
5 to 2:
fs Proportions........| 1 1 Au 3.3 | 1 15) Besa 2.0 | 3.411 DAN eyes |i PAST ONS
A Quantities byt dey 29. 1.75| .36} . 86] 1.63] .46/ .79| 1.55] .46/ .78| 1.52] .50| .74| 1.53) .62) .62
4 to 2

Proportions......-- 1 1.4/3.6) 1 TESeoaGEl yl 1.9} 3.7) 1 Ppa Vat fap 2 Guledaa
‘ poets ae Eee ete fgeesole ON debs 243) 85) eon) 42° 683) 1.49) 46), St) Lalo 7i0. 69
tto3

Proportions.......- 1 USB Bi7F|eds 1.8} 3.8] 1 1.8] 3.9 | 2 2.1 | 4.0} 1 2.4 | 3.3
4 Quantities. ........ 1.68} .33} .92| 1.58] .42| .89) 1.49) .40) .86) 1.49) .46) .88) 1.49 .53) .63
Shoe
- Proportions........| 1 La yae An 1 2 AGED AP el DAM 2) Dahl PAN P57) |i a | ae

Quantities. ..__..-. 1290 AS SOS lesa) 05|) ocO3|) Leva) OL|) oa|) 1.67) 64) soold. al 9] oo
3 to 13:

: Proportions........| 1 Ieper thi|li ah 2.0, |) 2.8 |) 1 PENS 2 OMle eda 3.0 | 2.0
Aa Quantities......... 1.82} .46]) .73) 1.79) .50) .70) 1.63) .55) .65) 1.61) .59) .64) 1.62) .73) .48
2 to 2:

Proportions........| 1 Ley Ae shi al 2.0} 3.1] 1 Det moa tay el 2.5 | 3.0} 1 3.0 | 2.4

Quantities. ........ 175) AST #2 80! 12631). 48]| .75| 1-55) 03). 72) 1252) 256) 67) 1053) 68) 0
3 to 22:
©” Proportions.......}1 | 1.713.3|1 |20|3.5/1 |23|/3.4/1 |24]34]1 |29/28

Quantities......... 1.72} .43| .84] 1.63} .47] .83/ 1.51) .52) .76) 1.49) .53) .75) 1.50) .64) .62
to 3:

r Proportions........ 1 17 4a ee at DO |e yee Qesiliouee Wak 2.4/3.6] 1 2:13.4| eoeil

Quantities......... 1-68] .43) .88) 1.58! .47| .87) 1.49) .51) .81) 1.49) .53} .79) 1.49) .62) -68
1 to 13:

Proportions........| 1 TS TAH sed 2.0] 2.9} 1 PAS Pee Ay al PG) | PAGE PL 3.1 | 2.0

aaufities Se ee 1, 82} . 46) . 75) 1.68) .50| .73) 1.63] .55) .65) 1.61) .62) .62| 1.62) .75) .48
1to2

Proportions........ 1 IRs Weer Ay aL DOSS) |b Q2alises, |e 2.4} 3.3] 1 3.0 | 2.6

Quantities......... 1.75} .39| .83] 1.63} .46] .85] 1.58] 251) .76) 1.52) .54) .74) 1.53) .68) .59
1 to 23:

Proportions.......}1 |1.4]/34/1 | 1.9] 3.8 SOLS a seay a leary | aa

Quantities......... 1.72| .35| .86] 1.58] .45] .89) 1.51) .44] .83) 1.49) .51) .81) 1.50) .59) .69
1to3:

Proportions........} 1 teouios On| TES 4,04 2.0} 3.9] 1 222 ea abe 2.7 | 3.3

Quantities... <. 1,67] .33) .90) 1.58) .42) .94/ 1.49) .44/ .86) 1.49 sap] Ge 1.49} .59| .73

10 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

QUANTITIES OF MATERIALS REQUIRED.

The quantities of materials theoretically required for concrete pave-
ments of various proportions, thicknesses, and widths are given in
the appendix, pages 61 and 62. The quantities of aggregates are given
in cubic yards. To correct to an approximate tonnage basis, the fine
ageregate quantities should be multiplied by one and one-half and the
coarse aggregate quanties multiplied by one and one-third. In prac-
tice an allowance must also be made for waste or loss in handling
these materials. This allowance should be approximately 2 per cent
for cement, from 2 to 4 per cent for fine aggregate, and from 3 to 7
per cent for coarse aggregate, depending upon the method used in
handling the material.

DESIGN CF CONCRETE ROADS.

There are two general types of concrete pavement, known, respec-
tively, as one-course and two-course pavement. The former con-
sists of one course of concrete, all of which is mixed in the same pro-
portion and composed of the same kind of materials, while the latter
consists of two courses, usually mixed in different proportions and
containing different kinds of aggregate. The one-course pavement
is much simpler to construct than the two-course type. For the one-
- course construction it is customary to employ a coarse aggregate of
average wearing qualities, which can readily be obtained from com-
mercial sources.

Where a very large volume of steel-tired traffic is anticipated, how-
ever, it is sometimes desirable to provide a surface of exceptionally
good wearing quality to resist the abrasive action of this particular
kind of traffic. Inasmuch as aggregates having high resistance to
wear, such as granite and trap, frequently have to be imported from
long distances at great cost, the cost of a road composed entirely of
this aggregate would be almost prohibitive. This has led to the
development of the two-course type of construction in which local
coarse aggregate of average or low wearing qualities is used in the
lower course and imported aggregate with high resistance to wear
is used in the top course. For example, if the only materials locally
available for use as aggregate are of inferior quality, it would usually
be more economical to use them for aggregate in the lower course of
a two-course pavement and import aggregate for the wearing course
than to employ a one-course pavement and import all the aggregate.
The coarse aggregate in the top course is somewhat smaller than in
one-course construction and the thickness of the top course is usually
about 2 inches.

In the two-course construction it has been somewhat general
practice to permit leaner proportions for the lower course than would

PORTLAND CEMENT CONCRETE ROADS. sap

be required for one-course construction, but it is not believed that this
practice is justifiable unless the thickness is correspondingly increased.
With the development of modern traffic, the load-carrying capacity of
the pavement is an important consideration, and the requirements of
strength should govern the proportions of the lower course in two-
course construction to the same extent as in one-course construction.
The construction of a two-course pavement involves construction diffi-
culties in mixing and handling two kinds of concrete and usually in
securing two kinds of coarse aggregate, especially if one kind is
shipped by rail, and therefore usually costs correspondingly more to
build than the one-course pavement.

Under modern traffic conditions the amount of abrasive traffic on
main roads is rapidly decreasing and observations of concrete pave-
ments built with aggregates of average wearing qualities that have
been in service from 6 to 8 years fail to show any serious wear from
abrasion. Except under unusual conditions, therefore, it would not
appear necessary to resort to two-course construction.

Besides the two general types of concrete pavement described
above, there are several patented types, but so far as is known these
do not possess any particular advantages and will not be discussed in
detail. The one-course pavement is believed to be better adapted to
most ordinary conditions than any other type of concrete pavement
and will be principally considered in the following discussion.

WIDTH OF PAVEMENT.

The width of pavement necessary will depend upon the frequency
with which vehicles are expected to pass each other, the character of
the vehicles, and their speed. For single-track roadways a width of
10 feet is usually adopted. This width is ample for a single line of
traffic, but passing vehicles will be forced to use the shoulders of the
road which consequently will require considerable maintenance. The
frequency with which vehicles pass each other has made it necessary
in some instances to construct shoulders of broken stone or gravel.

It is believed that all trunk-line roads and roads of primary State
systems should be constructed to accommodate two lines of tratfic,
whether the necessity for such a width exists at the time of con-
struction or not. The history of highway improvement shows that
there is always a tremendous increase in traffic upon the completion
of the improvement. This potential increase usually justifies the
double-track road. Where funds are the controlling factor in the
construction of the primary system, it may be desirable to construct
a single-track pavement in certain sections and make provision for
widening the pavement at a later date when the volume of traffic
justifies the expense. In doing this the road should be graded the

12 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

necessary width for a double-track pavement and a 9-foot pavement
built to one side of the center line of the grade. In widening a pave-
ment of this type to 18 feet it would only be necessary to lay a slab 9
feet in width adjacent to the original slab. A typical cross-section
for a pavement of this type is shown in Figure 7, page 28.

The character of vehicles, together with the clearance necessary
for safety in passing, will largely determine the width of pavements
for double-track roads. Motor-truck traffic has grown to such pro-
portions that it has been necessary in many States to limit by statute
the size of load and the total width of body. The maximum width
of truck body generally permitted is 8 feet. If ample clearance is
provided for the passing of trucks of maximum size a desirable
factor of safety will be provided for smaller trucks and passenger
motor vehicles. For slow-speed traffic, such as truck traffic, a clear-
ance of 3 to 3} feet is necessary for safety, while for high speed
traffic, such as automobiles, a clearance of at least 5 feet should be
provided. The amount of truck traffic is small, in comparison to au-
tomobile traffic, except in the neighborhood of large cities, so that
the frequency with which one truck passes another is almost neglible
in comparison with the frequency with which automobiles pass
trucks. If, therefore, ample clearance is allowed for the passage of.
an automobile and a truck, the maximum of safety will be obtained
at the minimum of cost.

The diagram, Figure 1, shows the width of pavement necessary
for reasonable clearance for trucks passing each other and for an
automobile passing a truck. At an average speed of 30 miles per
hour it is unreasonable to expect the driver of an automobile to drive
with the wheels closer than 14 feet to the edge of the pavement. For
trucks at an average speed of 15 miles per hour, this distance should
not be less than 12 feet on account of the great width of the rear
wheel. Inasmuch as a certain amount of truck traflic is to be ex-
pected on all main country roads, the minimum width of pavement
for this class of road should be 18 feet. Where the frequency with
which trucks pass each other becomes a big factor, as in the neigh-
borhood of large cities, the minimum width of pavement should be
20 feet.

THICKNESS OF PAVEMENT.

The determination of the proper thickness of a concrete pavement
for different kinds of traflic is a very complex problem in applied
mechanics, and depends to a large extent on certain factors which at
present are more or less indeterminate. In the first place, the loads
acting on a pavement are not merely static loads, but are apphed with
considerable impact. This impact varies with the roughness of the

PORTLAND CEMENT CONCRETE ROADS. 13

pavement, the speed of the vehicle, the character of the tires, and
the percentage of the total load which is carried above the springs
of the vehicle. Under very unfavorable conditions it may be as high
as five times the amount of the static load.

The pavement itself depends upon the subgrade for support, and
this support is extremely nonuniform in character. The supporting
power of a subgrade depends upon the type of soil, its capillarity, the

| (eed

eas bea. 5-0 —— = /-6---—— §-2 —e|5-_— 4- —/-6
/8-0

AS
ea ae eee
a ee ae
20-0 ”

TRUCK PASSING TRUCK .

Fig. 1.— Width of road required for safe passage of vehicles.

proximity of ground water, the condition of surface drainage, the
amount of sustained rainfall, and the extent of freezing and thawing.

All of these factors are extremely variable, and in combination are
almost indeterminate, so that it 1s almost impossible to reduce the
determination of pavement thickness to a simple mathematical com-
putation. The behavior of concrete pavements of known thickness
under known soil conditions and known conditions of traflic is the
most satisfactory index of the thickness of pavement required.

It has been more or less customary in the past to use a flat subgrade
for concrete pavements, and obtain the necessary crown in the pave-

14 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

ment by making the concrete thicker at the center than at the sides.

The flat subgrade was adopted originally, no doubt, for the reason
that it was simpler to construct than any other form. For a double-
track pavement, however, where two lines of traffic are accommodated,
the use of a flat subgrade imposes the maximum wheel load on prac-
tically the thinnest part of the pavement. Under heavy traffic con-
ditions this has often led to complete breakdowns of the edges of the
pavement. ‘This action is greatly accentuated where diagonal trans-
verse cracks occur. For a double-track pavement where the volume
of traffic confines the limits of travel in each direction, it is essential
that the edges be of the same thickness as the remainder of the pave-
ment. This can be secured by using a crowned subgrade and a uni-
form thickness of pavement.

On a sandy or sandy-loam soil, where the traffic consists mainly
of horse-drawn vehicles and passenger automobiles, with compara-
tively few trucks, a thickness of pavement of 6 inches will often
prove satisfactory. As the volume of truck traffic and the weight
per truck load increase, the pavement should be made correspond-
ingly thicker. A greater thickness should also be used on soils of
poor bearing quality which are difficult to drain than on soils of
good bearing quality which are easily drained.

For the average condition of soil under traffic conditions up to
and including 150 trucks per day, a thickness of 8 inches is believed
desirable. In the neighborhood of large cities where a large volume
of heavily loaded truck traffic 1s to be expected, the thickness should
preferably be 9 inches, and under very unusual conditions a thick-
ness of 10 inches may be necessary. A failure of a thin concrete
pavement is shown in Figure 2, Plate X.

CROWN OF PAVEMENT.

A concrete pavement lends itself readily to the construction of
low crowns. A Jow-crowned road is very desirable for the traffic.
Water does not damage the surface of a concrete road and under
present traffic conditions the wear of the surface is comparatively
small, so the necessity for a high crown does not exist in this type.
The amount of crown need not be any more than is necessary to
shed the water from the surface, taking into consideration the small
imperfections and depressions which exist in it. A crown of one-
eighth to one-fourth inch per foot is sufficient. In the operations of
finishing a concrete pavement surface a slight amount of crown will
be lost, so that if the tamper is cut to a true 2-inch crown, the re-
sulting crown in the pavement will closely approximate 13 inches.
This fact should be taken into consideration in specifying the amount

PORTLAND CEMENT CONCRETE ROADS. 15

of crown. The crown of a pavement may be either an arc of
circle or a parabolic curve. In road construction it is generally cus-
tomary to make it an arc of a circle.

SUPERELEVATION OF CURVES.

For modern traffic it is becoming customary and desirable to
superelevate pavements on all curves. Superelevation of pavements
compensates centrifugal force, reduces the danger of skidding on
curves, and induces traffic to keep to the right side of the road. The
amount of superelevation necessary will depend upon the radius of
the curve and the speed of the traffic, but under no circumstances

ine ee URVE |SHOWING
AMOUNT | OF SUPERELEVATION| PER |FOOT, 0.13

aS

OF WIDTH FOR VARIOUS RADII.
Based ona speed of 25 mi. per hr Ol

net Pe tot uh en ean .
d PRE E= Slope in feet per ft. of width. oO.

S= Speed in miles per hour
R= Radius of curve in feet.

Ht} Note} For radii from 2000' to 2500'use "or .02'per ft.
(a eee M | 2500 to 4000 use g or .014 per ft 0.08
a | 4000' to 6000' use gor .Ol per ft at
t For radii qreater than 6000 no superelevation. | 007
aed In choosing rate of superelevation | from
curve use nearest 0! ft. _| e606

a

°o
=
%&

O
5
e
Olin eel e ae
ale is os | ~

AMOUNT OF SUPERELEVATION IN INCHES PER Foot of WIDTH
OD Ply
AmMouNT OF SUPERELEVATION IN FEET PER Foot oF WIDTH

poles | ae eee

Fie. 2.—Curve showing superelevation per foot for curves of various radii.

should it be so great as to be objectionable or dangerous to horse-
drawn traffic. The maximum superelevation for this latter class of
traffic should not exceed 1 inch per foot of width. The speed of
other vehicles on curves of short radius must therefore be reduced
to conform to this superelevation. If this maximum be adopted, the
amount of superelevation for the various radii of curvature may be
easily computed. The curve, Figure 2, shows the amount of superele-
vation per foot of width for curves of various radii and a superele-
vated curve is shown in Figure 2, Plate IX.

Superelevation may be accomplished by rotating the pavement
about its central] axis, i. e., lowering the inner edge of the pavement
and raising the outer edge. If drainage conditions will not permit

16 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

the lowering of the inner edge, the superelevation may be obtained
by rotating the pavement about the inner edge, 1. e., by raising the
outside of the pavement. The maximum superelevation should be
obtained at the point of curve and continued for the entire length
of the curve. The pavement should begin to gain superelevation at
a point on the tangent approximately 100 feet from the beginning of
the curve, reach a maximum at the point of curve, and ease off to the
regular pavement cross section the same distance beyond the point
of tangency.
WIDENING ON CURVES.

In rounding a curve the rear wheels of a vehicle travel on a shorter
radius than the front wheels. On this account a greater width
of pavement is occupied by the vehicle on curves than on tangents.
The additional width varies with the radius of the curve, the gauge
of the wheels and the length of the vehicle. To allow the same
clearance between passing vehicles on curves as on tangents the
width of the pavement on the curves should be increased by an
amount equal to the sum of the additional widths required by the
two vehicles. If two vehicles of maximum size are assumed, l. e.,
trucks of 204-inch wheel base with a 5-foot gauge, it will be found
that for curves of 30-foot radius the amount of widening required
is 12.5 feet, while for curves of 150-foot radius the additional width
is 2 feet and for a radius of 500 feet, only 0.5 foot. For curves of
more than 500-feet radius the additional width required is neghegi-
ble.

If the passing vehicles are two automobiles of averge size instead
of two large trucks the additional width required will be less
on account of the shorter wheelbase and narrower gauge of the
smaller vehicles. If provision is to be made for the passage of
a truck and an automobile the extra width required will be between
the larger and the smaller amount. In widening curves the added
width should be consistent with the provision that has been made
on tangents. If the normal section on tangents is 16 feet wide the
road will accommodate two automobiles in passing and the addi-
tional width on curves should be designed to provide for two such
vehicles. The 18-foot normal section provides for the passage of
an automobile and a truck, and the 20-foot section accommodates
two large trucks. The additional width on curves, therefore, should
provide for the passage of vehicles of the same type. The method
of computing the amount of widening required is illustrated in
Figure 3.

Theoretically the amount of widening determined in this manner
is all that is required, but an additional allowance of a foot or two

PORTLAND CEMENT CONCRETE ROADS. T?

is generally made to allow greater clearance between the passing
vehicles on curves for additional safety. As the clearance allowed

EDGE OF STANDARD SECTION

Rg. R /
EDGE OF WIDENED Bearley
PAVEMENT /

R= Radius oF CENTER OF STANDARD SECTION OF PAVEMENT.

W=WIDTH OF STANDARD SECTION OF PAVEMENT.

@= DISTANCE FROM EDGE OF PAVEMENT TO CENTER OF NEAREST
WHEEL (TAKEN AS Iz FT. FOR PASSENGER CARS AND [3 FT. FOR
TRUCKS).

C=CLEARANCE BETWEEN VEHICLES.

L=LENGTH oF WHEEL BASE OF VEHICLES (TAKEN AS 12 FT. FOR
PASSENGER CAR AND !7 FT. FOR TRUCK).

G= GAUGE OF VEHICLES (TAKEN AS 4 FT FOR PASSENGER CAR
AND 5 FT FOR TRUCK).

b=WIDTH. OF VEHICLES OVERHANGING WHEELS (TAKEN AS 3 FT FOR
PASSENGER CAR AND [3 FT FOR TRUCK).

R=R+5W-@ (R+@*=R5-L? R,+G=VR3-Le
R,=-VRE-U°-G R3=R,-(C+2b. (Rat G)=RZ-LE
z 1 a Pa =\/ CE ae Ne ToTAL WIDTH REQUIRED =
R4+G= R3 E Ra= R3 Ee G. R-R4gtat+ sw.
Fig. 3.—Method of computing amount of widening on curves.

on the tangents is from 3 to 34 feet, it is believed that a minimum
of 5 feet should be provided on the curves.
~ 101130°—22——_2

18 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

The table on page 19 gives the amount of widening for curves
on iG, 8; and 20 foot pavements, computed on the basis of the
above wesnu son for curves up to 500-foot radius. For curves of
greater radius than 500 feet the amount of widening would be
practically constant and would be based upon the greater clearance
required on curves for additional safety. At what point widening
should be discontinued is somewhat problematical, but it is believed
no additional clearance in passing is required for curves of 1,000
feet radius or greater.

It is now seine le agreed that the merenced width should be added
to the inside rather than the outside of the curve; but there is con-
siderable difference of opinion as to where the widening should
begin. If the path of a vehicle around a circular curve is analyzed,
it will be found that as the front wheels conform. to the curve, the
rear wheels effect a gradual transition to concentric curves of shorter
radu and then follow these concentric curves around the circle. This
transition of the rear wheels to curves of shorter radii begins on the
tangent approximately one vehicle length from the point of curve
and is generally completed in from one to one and one-half vehicle
lengths on the curve. The necessity for curve widening, therefore,
exists practically for the entire length of the circular curve; and
for curves ordinarily used in highway practice, full widening should
obtain both at the point of curve and the point of tangency.

The logical method of widening curves, therefore, is on the inside,
full amount of widening for the entire length of circular curve. To
gain this width at the two ends of the circular curve it is necessary
that the widening of the pavement he begun at some distance from
the points of curvature and tangency, thus providing a widening
approach section to the curve. Theoretically, the length of this ap-
proach section should be varied with the degree of the curve, but in
practice it is customary to employ a uniform length for all curves.
A simple design which has proved satisfactory is shown in Figure 4,
in which the approach section is in the form of a taper and the
widening is begun at a distance of 100 feet from the ends of the
circular curve. Instead of a straight-line taper, a transition curve
may be used. In this case the offset from the tangent to the circular
curve would be equal to the amount of widening and would deter-
mine the length of transition curve which would have to be used.
A transition curve, however, cannot be used on widened curves of
very short radii, because the amount of widening is so great and the
length of circular curve so small that a true transition curve will not
satisfy the conditions. For curves of 200-foot radius and over the
transition curve will give satisfactory results.

If it is desired to use transition curves to connect the circular
curve and the tangents, widening may be accomplished as shown in

PORTLAND CEMENT CONCRETE ROADS. 19

Figure 5. As the offset from the tangent to the inner circular curve
in this case will be increased by the amount of widening required,
the length of the transition to the inner edge of the pavement will
always be longer than the transition used on the outer edge of the
pavement. The use of transition curves will materially increase the
field operations of staking out the work, but it is believed their use
is desirable on curves of from 200 to 1,000 foot radius,

EDGE oF. Sab esse SECTION

TAPERED PORTION OF PAVEMENT

CENTER LINE OF STANDARD SECTION

R= Rapius oF CENTER LINE OF STANDARD SECTION OF PAVEMENT.
PC.= PoINT oF CURVE.

PT.= Point OF TANGENT.

W= WipTH OF STANDARD SECTION OF PAVEMENT.

A=ADDITIONAL WIDTH OF PAVEMENT ON ACCOUNT OF CURVE.
100 Feet = LENGTH OF TAPER.

NOTE:THE TAPER WILL NOT STRICTLY BE TANGENT TO THE WIDENED
PORTION OF THE CURVE AT THE PC. THE PoINT OF TANGENCY IS
SO NEAR THE PC, HOWEVER, THAT A SLIGHT SHIFTING OF THE
FORMS AT THIS POINT DURING THE SETTING WILL CONNECT THE
TAPER WITH THE CURVE WITHOUT ANY NOTICEABLE BREAK.
IN NO CASE WILL THE FORMS AT THE PC. HAVE To BE MOVED
MORE THAN .I5 Foor.

lic. 4.—A simple method of widening curves.

Table of curve widening.

Additional width of pave- Additional width of pave-

Radius ment required for— Radius ment required for—
of (0)
center center |
line 16-foot 18-foot 20-foot line 16-foot 18-foot 20-foot
curve. pave- pave- pave- curve. pave- pave- pave-
ment. ment. ment. ment. ment. | ment.
Feet. Feet. Feet. Feet. Feet. Feet. Feet. Feet.
30 8.0 11.0 14.0 125 ay 4.0 4.0
40 6.0 8.0 Le 150 ae 34 ah i
50 5.5 6.5 (ie 175 3.0 3.0 3.0
60 5.0 5.5 6.5 200 3.0 3h (0 30
70 4.5 5.0 aD 250 350) 3.0 2.5
80 4.0 4.5 5.0 300 3.0 200 2a
90 4.0 4.5 4.5 400 3.0 PA 2.0
100 4.0 4.0 4.5 500 2A. 5S 2.5 PY)

20 BULLETIN 1077, U. S: DEPARTMENT OF AGRICULTURE.
JOINTS.

Concrete contracts or expands with changes in temperature and
differences in moisture content. It also shrinks materially during the
period of setting and initial drying out. In practically all early
concrete pavements transverse expansion joints were constructed 25
to 30 feet apart, with the idea of relieving the pavement slabs of all
stresses due to expansion and contraction, thereby preventing trans-
verse cracking due to tensile stresses or failures due to compressive

tc)

acy = COORDINATES OF POINT OPPOSITE PC.
2C,U,;= COORDINATES OF PC,
F="OFFSET FROM TANGENT TO CIRCULAR CURVE.
2,= LENGTH OF TRANSITION CURVE.
°= CENTRAL ANGLE OF TRANSITION CURVE,
= CENTRAL ANGLE OF CIRCULAR CURVE FROM PC To PC,.
us= AMOUNT OF PAVEMENT WIDENING.

dle

7U
=I

M =HLOIM AWWYON

Fic. 5.—Method of widening curves using transition curves.

stresses. In these pavements it was found, however, that a majority
of the slabs cracked transversely, that it was very difficult to secure
a pavement with good riding qualities in the neighborhood of the
joints, and that if the expansion joints were not constructed so as to
be perpendicular to the surface of the pavement the end of one slab
was very likely to rise above the end of the adjacent slab. Not in-
frequently this relative movement amounted to 2 or 3 inches and in-
convenienced traffic very materially, If the joint varied from the

al te snp Bente sec sided 1

a

PORTLAND CEMENT CONCRETE ROADS. se |

vertical as little as 5°, this movement was likely to occur and
it was found difficult in construction work to avoid even greater
variations.

These findings led to the experiment of building pavements with-
out expansion joints, and it was found in pavements so built that the
_ transverse cracks did not occur more frequently than in those built
with expansion joints and that the shrinkage due to the setting and
initial drying out of the concrete provided sufficient room for such
expansion as occurred later from changes in temperature and mois-
ture content, except in pavements laid in cold weather. In pave-
ments laid in cold weather it appeared that the shrinkage due to set-
ting and initial drying out did not provide sufficient space for subse-
quent expansion caused by changes in temperature and moisture, and
local failures of the pavement were not infrequent.° Experience,
therefore, indicates that transverse joints are unnecessary in pave-
ments laid when the air temperature is generally above 50° F., but
are necessary in pavements laid in cold weather. The majority of
plain concrete pavements are now constructed without joints. Trans-
verse cracks will occur in pavements so constructed at more or less
regular intervals, averaging 30 to 50 feet apart. These cracks in
general are less objectionable than joints. They do not adversely
affect the riding qualities of the pavement, slipping of the slabs rarely
occurs, the cost of maintaining them is no greater, and, if properly
maintained, they do not materially injure the pavement.

It is customary to construct transverse joints in reinforced pave-
ments. They are generally spaced from 40 to 80 feet apart. The
method most often used in constructing transverse joints is to sep-
arate the sections of the pavement by means of specially prepared
bituminous felt boards. These are usually held in place by means
of properly shaped steel templates until the concrete is deposited
against them, after which the templates are removed and the con-
crete flows around the boards. The thickness of this joint has varied
in common practice from one thickness of two-ply tar paper up to
about one-half inch. A thickness of one-quarter inch seems to give
very satisfactory results when the joints are spaced not more than
40 feet apart. Joints of this kind are sometimes provided with metal
armor, which is intended to keep the adjacent edges of the concrete
from spalling off. It is claimed that armored joints require less
maintenance than other types, but. they are more expensive to con-
struct. As the amount of abrasive traffic on country pavements is
steadily decreasing, there does not appear to be any necessity for this
type of joint except under unusual conditions.

6A full discussion of the expansicn and contraction of concrete roads may be found in
U. 8S. Department of Agriculture Bulletin 532.

22 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

The use of longitudinal joints along the central axis of the road —
has generally been confined to pavements exceeding 20 feet in width. —
Where such joints have been used, it has been customary to construct —
one-half of the pavement width at one operation. After this portion
of the pavement has been completed, the remaining half portion is —

constructed. The edges of the longitudinal joint are rounded with }

an edging tool, and after curing the joint is filled with bituminous
material. The method of constructing a pavement in two half sec-
tions is particularly advantageous on some heavily traveled roads
where it is not possible to divert the traffic. The construction of a
pavement of this type can be carried on without diverting the traffic,
although the operations of the contractor are hampered somewhat,
resulting in slightly increased costs.

It has not been general practice to use a longitudinal joint in
the construction of pavements 16 to 20 feet wide, when the full
width of pavement has been constructed at one operation, but there
are several arguments in favor of this form of construction. From
observation of a large mileage of concrete pavements, it is found
that longitudinal cracks rarely occur in pavements 9 or 10 feet wide,
but frequently occur in pavements exceeding 16 feet in width. It is
reasonable to assume, therefore, that a longitudinal joint along the
central axis of the pavement would practically eliminate cracking.

Longitudinal cracks are more objectionable than transverse cracks
because they have a tendency to gradually increase in width. When
they occur along the line of wheel traffic the edges of the cracks
deteriorate rapidly unless carefully maintained. Another important
advantage of a longitudinal joint along the central] axis of the road
is that it serves to define sharply the limits of travel in each direc-
tion, thus providing a desirable factor of safety for road travel.

A longitudinal joint for full-width pavement construction should
be of the submerged type. A joint of this type usually extends from
the bottom of the pavement to within approximately three-fourth
inch of the surface. The purpose of the submerged joint is to facili-
tate and simplify the operations of striking, tamping, and finishing
the surface of the pavement, which would otherwise be rather difficult
with the joint extending through the pavement. A strip of 18 or
20 gauge metal, held rigidly in place by pins driven into the sub-
grade, will usually prove satisfactory. The metal should prefer-
ably be corrugated or deformed sheets so as to key the two sections
together. Reinforcing steel should be used to tie the two sec-
tions of the pavement together and prevent any lateral movement.
The reinforcing steel should be placed halfway between the top
and bottom of the slab. The practice of the Illinois highway de-
partment is to use five-eighths-inch deformed bars, 5 feet long, spaced

- ea

PORTLAND CEMENT CONCRETE ROADS. 23

10 feet center to center, extending an equal distance into each sec-
tion of the pavement. The metal joint may either be punched or
slotted to provide for the reinforcing steel. When the surface of
the pavement cracks above the submerged joint, the crack is filled
with bituminous material.

STEEL REINFORCEMENT.

Steel reinforcement in the past has been used in concrete pave-
ments, primarily to prevent excessive cracking. For this purpose
it has been customary to use wire mesh or expanded metal weigh-
ing from 25 to 40 pounds per hundred square feet. Equally satis-
factory results, however, can be obtained by the use of $-inch de-
formed bars spaced 24 inches center to center in both directions.
This reinforcing should be placed not less than 2 inches from the
finished surface of the pavement and should extend to within 2
inches of all joints, but not across them. Adjacent lengths of wire
mesh or expanded metal should be lapped from 4 to 8 inches. For
ease in handling, the wire mesh or expanded metal should be ob-
tained in flat sheets. The use of this kind of reinforcement will
add from 30 to 60 cents per square yard to the cost of the pavement
and this additional cost is no doubt responsible for the fact that con-
crete pavements have not generally been reinforced in the past. Re-
inforcement of this type, moreover, does not entirely prevent cracks,
but distributes them and keeps them small.

Under very severe traffic conditions and for pavements laid on
exceptionally soft subgrades which cannot be materially improved,
reinforcement may be necessary to give greater strength to the pave-
ment by distributing the load over a larger area. Deformed bars
should be used for this reinforcement and the percentage of rein-
forcement required will depend on the traffic loads, the condition
of the subgrade, and the range of temperature and the variation in
percentage of moisture. The reinforcement should preferably be
placed both at the top and the bottom of the pavement and may vary
from 4 to 3 inch bars spaced from 18 to 24 inches center to center
in both directions. Reinforcement to give added strength to the
pavement is rapidly gaining favor among engineers, and it 1s now
being extensively used in localities where a large volume of heavy
traffic is to be expected.

Another form of pavement reinforcement—circumferential rein-
forcement—consists of 2-inch bars, placed half way between the top
and bottom of the pavement, approximately 6 inches from the edges,
and completely around the slab. This form of reinforcement gives
added strength at the edges where cracks usually begin, and on a soft
subgrade serves to hold the pavement together should cracking occur.

al ee eee

24 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.
SHOULDERS AND DITCHES.

The width and kind of shoulders necessary for concrete pavements
will depend upon the width of pavement and the volume of traffic.
On single-track pavements the shoulders must be sufficiently wide
to provide for safety of passing vehicles and must be composed of
material which will support them satisfactorily. On double-track
pavements the shoulders should be of sufficient width to allow for
irregular and unexpected actions by inexperienced drivers or fright-
ened animals, and, where the volume of traffic is large, to permit auto-
mobiles to turn out onto the shoulders for minor adjustments or
tire repairs without blocking the traveled way. The width of each
shoulder, then, should be not less than 5 feet; a width of 6 or 7 feet
is preferable.

It has generally been customary to construct gravel or macadam
shoulders to single-track roads on clay soils. This may be accom-
plished by constructing gravel or macadam strips 3 feet wide on
each side of the pavement, or in the case of a single-track pavement
built on one side of the center line by placing the gravel or macadam
strip all on one side and making the width 6 feet. These gravel or
macadam strips are usually 4 to 6 inches thick. On soils of a
eravelly nature which have rather good supporting power when wet,
metaled shoulders are not used. A double-track road should be wide
enough to permit the passing of vehicles without turning out on the
shoulders, so no shoulder should be necessary for this pavement other
than the natural soil.

The slope of the shoulder should be such as will readily dispose of
the water, and at the same time not be so steep that it will appear dan-
gerous to drive on. Shoulders along a low-crowned pavement should
have a slope as flat as possible so as not to accentuate the change in
slope. A slope of $ inch to 1 foot should prove satisfactory. Inas-
much as the shoulders of a concrete road are seldom rolled, some slight
settlement takes place, and it is usually found that if a very flat shoul-
der is constructed it will have all the slope necessary after the road
has been opened to traffic for a short time.

Surface ditches are usually constructed of two general shapes—the
V shape, and the trapezoidal shape. In rolling country, where the
surface water can be turned away from the road at frequent intervals,
the V-shaped ditch has proved very satisfactory. Where it is neces-
sary to carry water in the ditches for considerable distances the trape-
zoidal ditch should be used. The bottom of the ditch should be at
least 18 inches lower than the center of the road; and when a large
volume of water is to be carried the minimum depth should be 24
inches. The slopes to the ditches from the shoulder should not be
steeper than 2 to 1.

| :

PORTLAND CEMENT CONCRETE ROADS. 95
CURBS AND GUTTERS.

To prevent erosion of the side ditches and the danger of washouts
on relatively steep grades, some form of paved gutter, or combined

curb and gutter, must be used. The amount of erosion depends upon
the velocity of the water and the kind of soil. On soils of loose tex-
ture a small accumulation of water on grades as low as 3 per cent is

sufficient to cause considerable erosion; while some soils of dense tex-

ture are not materially eroded on grades as high as 6 per cent. The

grade, therefore, on which it will be necessary to use a paved gutter
will depend upon the kind of soil. In general, it will be found desir-
able to provide paved gutters on all grades greater than 5 per cent.

A paved gutter, or the combined curb and gutter, may often be
used to advantage in reducing the amount of grading in through and
hillside cuts. For example, in deep cuts the amount of grading can
often be reduced as much as 35 per cent by omitting the shoulders

and side ditches and providing curbs along the edges of the pavement,

so that the sides of the pavement serve as gutters. Similarly on
heavy hillside work, by omitting the shoulder and ditch next to the
hill and using a curb on one side, a considerable saving in grading
can be effected. Inasmuch as the use of curbs confines traffic to the
pavement, the width of the pavement should be slightly mcreased
where curbs are employed. If curbs are used in connection with a
standard 18-foot pavement with earth shoulders, the width between
curbs should be at least 20 feet.

The paved gutter, or the combined curb and gutter, can be con-
structed as an integral part of the pavement, but this operation is
a slow, tedious one which slows up the laying of the main body of
the pavement and prevents the use of a mechanical finishing machine
to the best advantage. Better results will be obtained if the regular

width of pavement is constructed first and the gutter, or curb and

eutter, constructed later. If this procedure is adopted, the gutter, or
eurb and gutter, should be tied to the main pavement by short pieces

_of reinforcing steel. This can be accomplished by drilling holes in

the pavement forms midway between the top and bottom and insert-

ing bars 3 feet long, spaced 24 to 3 feet apart, so they will project into

the pavement about one-half their length. The bars should not be
bent to conform to the gutter section until the forms have been re-

‘moved. Joints should be placed in the gutter, or the curb and gutter,

at points where joints exist in the pavement. Typical details of

.

circular and V-shaped gutters and a combined curb and gutter are
shown in Figure 6.

BITUMINOUS SURFACE TREATMENT.

A coating of bituminous material and sand, gravel, or stone chips
applied to the surface of a concrete road is known as a bituminous

26 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

surface treatment. The thickness of the coating is generally from
one-fourth to three-eighths inch. Bituminous surface treatments
have been used to some extent, principally because it was thought
that they served to protect the concrete pavement by cushioning the

: ES 7 : Z 074
PS es 2fods 3-6 /09
WIIvrES, . 2-6 centers

DETAIL OF V SHAPED GUTTER ;

C = CROWN OF PAVEMENT

DETAIL OF CURB N

3 rods 3-6 ‘tong
2~6° Centers

DETAIL OF CURVED GUTTER

Fic. 6.—Typical details of gutter and curb.

impact of traffic and preventing the abrasion of the surface. Their
use is now being generally discontinued. It is found that a bitu-
minous surface approximately one-fourth inch thick has little, if
any, cushioning value and consequently does not lessen the impact

PORTLAND CEMENT CONCRETE ROADS. Dar

to any appreciable extent. The amount of abrasive traffic on country
roads is steadily decreasing and a well-constructed concrete pave-
ment no longer shows any marked deterioration through abrasive
action. The chief advantage of a bituminous surface treatment lies
in the fact that cracks are automatically bridged over as they appear
and surface water is prevented from reaching the subgrade through
these cracks. The difficulty of securing proper adhesion of the bitu-
minous surface to the concrete, its cost, and the necessity for continu-
ous maintenance of the surface constitute its greatest disadvantages.
It is believed that these disadvantages greatly outweigh any possi-
ble advantages which might be obtained through its use.

THE CROSS-SECTION.

Typical cross sections of pavements based upon the foregoing dis-
cussion of design are shown in Figure 7.

CONSTRUCTION.
GRADING.

The grading requirements for concrete pavements are essentially
the same as for other types of pavement. The shoulders may either
be roughly built at the time the heavy grading is done or be con-
structed after the pavement has been placed. If the shoulders are
roughly built before the pavement is placed, frequent drainage open-
ings must be left in them to insure the rapid drainage of the sub-
erade during periods of rainfall. This is very essential if the pave-
ment operations are not to be delayed by a poor subgrade.

DRAINAGE.

Surface drainage is secured by means of the pavement crown, the
slope of the shoulders to the ditches, and frequent outlets for the
water from the side ditches through culverts and bridges. In addi-
tion to surface drainage, soil conditions are sometimes such as to
require subdrainage. Subdrainage is usually desirable over low,
swampy ground and at points where ground water is encountered on
hillsides or in deep cuts. Subdrainage may be effected by the use of
drain tile, laid in trenches back filled with stone, gravel, or other
porous material, or by the use of V-drain foundations in which large-
sized stone is used and outlets are provided at all low points in the
gerade. The use of a V-drain foundation or any other form of pre-
pared porous foundation under concrete pavements serves only to
lower the point of support of the pavement. A somewhat wider dis-
tribution of pressure is secured by the use of these foundations; but
on soils requiring this wider distribution of pressure it is believed it
can be more cheaply obtained by reinforcement than by the use of
the prepared foundation. The most effective subdrainage for con-
crete pavements is obtained by the use of tile laid under the outer

28 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

edges of the concrete pavement, back filling the trench to the level
of the bottom of the pavement with stone or gravel. Whether the
tile should be used under both edges of the pavement will depend

TYPICAL SECTION OF I8FT. CONCRETE ROAD
WITH FLAT SUBGRADE

TYPICAL SECTION OF 16 FT. CONCRETE ROAD
WITH CROWNED SUBGRAOE
“C SHOULD GE FROM 13 TO FS

SECTION WITH ONE CURB
FOR SIDE HILL CUTS

UL rods 3-6 long, 2-6 Choc. gr0ds 3-6 long 2-6 Ehoc

SECTION WITH GUTTERS
USE EITHER STYLE OF GUTTER ACCORTING TO CONDITIONS

“C “SHOULD BE FROM 15 To2”

Fic. 7.—Typical pavement cross-sections.

upon the location of the pavement. On sidehill work one line of
tile under the edge of the pavemént nearest the hill will often suffice,
but through cuts it will probably be necessary to use the tile on

PORTLAND CEMENT CONCRETE ROADS. 29

both sides. For a more detailed description of the use of tile drains
see Bulletin 724, United States Department of Agriculture.

PREPARATION OF THE SUBGRADE.

The essential qualities of the subgrade are uniformity in grade,
in cross-section, and in firmness.

The purpose of the rolling to which it is customary to subject the
subgrade is to secure uniform firmness. Whether it accomplishes
this result is a point upon which opinions differ considerably. Cer-
tainly no amount of rolling will result in uniform firmness if trucks
or teams are driven over the subgrade to supply the mixer, Under
certain conditions it is believed that no rolling is required. In par-
ticular it is not believed necessary to roll a newly graded road which
has been closed to traffic and which has thoroughly settled before the
pavement is placed, providing the concrete materials are hauled to the
mixer by means of an industrial railway.

It is difficult to obtain uniform firmness by the use of the customary
three-wheel type of macadam roller, because a small strip of the sub-
grade, wheel-gauge distance from the sides of the road is subjected
to twice as much rolling as the edges. The tandem roller is not
open to this objection, and it is believed that a condition of uniform
firmness can be more nearly secured with a roller of this type than
with any other kind.

Any soil with a clay content that 1s unduly compressed by rolling
will swell considerably upon addition of moisture. Unless uniform
firmness has been secured by the rolling, the subsequent absorption
of moisture will result in uneven swelling which will outweigh any
advantage which might have been obtained by rolling. For these
reasons it is believed that, in general, light rolling is to be preferred
to heavy rolling.

When an old macadam or gravel road is to be surfaced with con-
erete, the entire surface of the road should be scarified and plowed
to the full depth of the existing surface before the subgrade is shaped
to receive the concrete. If this is not done it will be almost impossi-
ble to secure a uniformly firm subgrade. In case the concrete sur-
facing is to be wider than the old road surface, the failure to loosen
the old surfacing to its full depth will leave a hard, compact core
in the subgrade. The uneven support afforded by subgrades with
such hard cores is the cause of frequent longitudinal cracks in con-
crete pavements constructed over old macadam or gravel roads.

‘The uniform firmness of the subgrade should extend for a dis-
tance of at least 1 foot beyond the edges of the pavement, in order
to provide a solid support for the side forms.

After the rolling the forms are set true to line ard grade and they
are then used as a guide for the finishing or trimming operations.

80 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

y]

The finishing may be accomplished either by picks and shovels or
by the use of a subgrade planer which rides upon the side forms.
When materials are delivered to the mixer by hauling over the sub-
grade it is generally necessary to finish with picks and shovels. If
materials are delivered by industrial railway, so that the subgrade
is not used for hauling, it will usually be economical to use a sub-
grade planer. The planer, which is generally drawn by the roller,
has its cutting edges so arranged that the slight excess of material
trimmed from the subgrade is deposited in windrows at the quarter
points, from which it is shoveled to the shoulders. For efficient use
of the planer the rough grade should be slightly higher than the
finished surface, a condition which is desirable in any case for the
reason that it leads to the construction of subgrades of more nearly
uniform firmness. Plate I, Figures 1 and 2, illustrate the construc-
tion and use of the subgrade planer and the finished subgrade.

The cross section may be either flat or shaped to conform to the
finished surface of the pavement. In either case the allowable varia-

6 aS —/ less thon half width of PQVEMENT

Fic. 8.—Details of nail template used to test the subgrade.

tion from the true grade and cross section is usually limited to one-
eighth inch. This small variation is intended primarily to insure
that the fuil thickness of pavement will be secured at all points. The
subgrade is tested by means of a nail template (Fig. 8), which is
moved back and forth over the forms. Should the test show that
any portion is too low, the low area is generally filled with concrete
as an integral part of the pavement, though sometimes the contractor
is permitted to fill it with hand-tamped earth. While the engineer is
charged with securing the full thickness of pavement required by
the plans, the contractor aims to furnish that thickness and no more,
because any additional concrete represents loss which rapidly runs
into a large sum. The natural result is a subgrade as true to grade
and cross-section as it is practicable to obtain.

FORMS.

The side forms for concrete pavements may be of steel or wood.
Steel forms are preferable and should be used whenever the pave-
ment to be laid exceeds one-half mile in length, and when machine fin-
ishing is to be used. A number of makes of steel forms can be pur-

PORTLAND CEMENT CONCRETE ROADS. 81

chased. If the pavement is to be machine-finished, heavy forms
are desirable and usually are more economical than light ones, as
they hold their shape much better under the vibrations set up by the
finishing machine. The forms should always be set true to line
and grade before the subgrade is finished, in order to serve as a guide
_ for the finishing. It is very essential that the forms be firmly sup-
ported and bear uniformly upon the subgrade, as any sag produces
an irregular surface in the pavement. The ends of the different
sections of forms should be fastened together so that no relative dis-
placement occurs. The joints between the sections on the two sides
of the road should not be opposite each other, but should be stag-
gered. The height of the forms should preferably be equal to the
thickness of the pavement at the edge. Forms 1 inch less in height
than the edge of the pavement can be used satisfactorily, however,
by bolting under them a 1-inch strip of wood. These wood strips
should be somewhat wider than the base of the forms, so that addi-
tional bearing can be secured. In States that use a variable thick-
ness of pavement at the edge this arrangement reduces the amount
of forms required for different classes of work.

Forms for concrete pavements should always be oiled before the
concrete is placed against them. This oiling prevents the concrete
from sticking to them, makes cleaning easy, and prolongs the life
of the forms. Any crude oil can be used for this purpose and
approximately 1 barrel per mile will be required.

The use of bent forms should be prohibited. It is usually specified
that variations in the surface of the pavement of over one-fourth
of an inch in 10 feet will not be permitted, These variations in the
surface of the pavement are caused to a large extent by the forms,
so it would appear that no greater variation should be permitted in
the forms than is permitted in the pavement. Forms, therefore,
should not be used if their top surfaces vary more than one-fourth
inch when tested with a 10-foot straightedge. A sufficient number of
forms should be provided so that it will not be necessary to remove
them within 12 hours after the concrete is placed.

HANDLING AND HAULING MATERIALS.

For handling and hauling the materials used in concrete pave-
ment construction a number of different methods may be used. The
most economical method to employ will, of course, depend upon the
particular problems of the work in question. The discussion of
this subject will be confined to the general methods which may be
employed and the advantages and disadvantages of each.

Nearly all of the materials used in concrete pavements are shipped
by rail. The method of unloading the materials from railroad cars
will depend to a large extent upon the method of handling the re-

Sa BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

mainder of the work. The following methods may be employed: —
(1) Unloading by hand into wagons, trucks, or into light movable

bodies which are hung against the side of the car and from which

the material is dumped into wagons or trucks; (2) mechanical un- — |
loaders, using belt conveyors, discharging into wagons or trucks; —
(3) bucket elevators or skip hoists from pits below the track, dis- —
charging into bins; (4) a clam-shell bucket on a stiff-leg, or guy-line —

derrick; (5) a clam-shell bucket on an auto crane or locomotive
crane. (See Fig. 1, Pl. VI.) The first three of these methods can

be employed to advantage where a comparatively small amount of —

material is to be handled and this material can be obtained in bot-

tom dump gondola or hopper cars. They can only be used, how- |
ever, where the materials, are distributed on the subgrade or placed
in stock piles on the shoulders of the road at short intervals. None —

of them affords any storage capacity at the unloading station.

Pavement construction is seasonal work. The peak demand for
materials naturally occurs during the midst of the construction sea-
son, and it frequently happens that because of this increased demand
regular deliveries and sufficient quantities of materials can not be
obtained for the work at hand. With uncertain transportation
facilities and a known shortage of railroad equipment for normal
business conditions, the storing of materials is practically imperative
if work is to proceed without interruption during the construction
season. ‘The storing of a considerable quantity of materials can best
be done by means of a clam-shell bucket on either a derrick or a
crane. On account of its ability to swing through a complete circle,
a guy-line derrick can store more material than a stiff-lege. If a
stiff-leg derrick is used, the maximum storing capacity will be
reached by setting the derrick with one leg parallel to the railroad
track. Cranes are considerably more flexible in operation than der-
ricks, and it is possible to store a large amount of material if the
storage piles parallel the track. In their principles of operation
auto and locomotive cranes are the same, the only difference being
that locomotive cranes are considerably heavier, have longer booms,
and operate on railroad tracks. If the reloading bin is stationary,
the amount of material that can be stored within reach of the bin
without rehandling will depend upon the boom length of the derrick
or crane. For large storing capacity a boom length of from 50 to
60 feet is desirable. With movable bins, however, good storing
capacity without rehandling can be obtained with cranes having a
boom length of 30 feet. The use of derricks and cranes combines the
labor-saving feature with the storage feature, and where the mate-
rials are proportioned or mixed at the unloading yard, their use is
practically indispensable.

Bulletin 1077, U. S. Dept. of Agriculture.

FIG. |.—SUBGRADE PLANER IN OPERATION.

Fic. 2.—THE FINISHED SUBGRADE.

PLATE

Bulletin 1077, U. S. Dept. of Agriculture.

PLATE Ii.

Fic. |1.—HAULING WITH TRACTOR TRAIN.

Fic. 2.—FINE AND COARSE AGGREGATE PILED ON SUBGRADE READY FOR USE.

Bulletin 1077, U. S. Dept. of Agriculture. PLATE III.

Fic. |.—CHARGING THE MIXER WITH A BELT CONVEYOR LOADER.

Fic. 2.—LOADING BATCH BOXES FROM SMALL STOCK PILES ON THE SIDE OF
THE ROAD WITH A BUCKET ELEVATOR.

Bulletin 1077, U. S. Dept. of Agriculture. PLATE IV.

Fic. I.—CHARGING MIXER WITH PROPORTIONED BATCHES HAULED iN
TRUCKS.

FIG. 2.—INDUSTRIAL RAILWAY HAULING PROPORTIONED BATCHES IN BOTTOM
DUMP BOXES.

PORTLAND CEMENT CONCRETE ROADS. 33

The equipment used for hauling must fit in with the general
method of conducting the work. The proper hauling equipment
will depend upon which of the three general methods of operation
are employed. By the first method, the materials entering into
the construction of the pavement are hauled separately to the work;
by the second, they are proportioned at the unloading plant; and
when the third method is used, the concrete is mixed at the unload-
ing plant and hauled to the road. If the first method of opera-
tion is employed the materials must be distributed on the sub-
grade (see Fig. 2, Pl. IL) or placed in stock piles on the road. Teams,
trucks, tractors, or an industrial railway may be used for this haul-
ing. Team haul is generally not economical where the maxi-
mum haul exceeds 38 miles. The economy of truck haul depends
largely upon the condition of the road hauled over and the care ex-
ercised in the operation and maintenance of the trucks. It should
not be attempted on a sandy or sandy-loam grade. No class of
equipment used in pavement construction depreciates as rapidly as
motor trucks if they are improperly operated. Constant changing
of drivers and the overloading of the truck are two of the prac-
tices which contribute to this rapid depreciation. Trucks for this
class of hauling should be equipped with power dump bodies.
_ractors are usually used in conjunction with a train of 4 or 5
ottom-dump specially constructed wagons each with a capacity of
about 5 cubic yards. The success of the tractor train is due to
‘he large quantity which it is possible to haul at one time. (See
“ig. 1, Pl. IL.) On account of the great width of pile which the
tractor train spreads, the proper distribution of the materials on
the subgrade is rather difficult. On roads of average width some
shoveling of the materials is necessary before the forms can be
set. An industrial railway may be used for delivering the material
to the subgrade, but when it is used, it would appear to be doubtful
economy to dump the materials on the subgrade and rehandle them
into the mixer when they can be handled directly into the mixer
from the industrial railway by the use of batch boxes.

When the materials are proportioned at the unloading point, the
only practicable method of hauling is with trucks or by industrial
railway. Under this method of operation the properly propor-
tioned materials for each mixer batch of concrete are dumped di-
rectly into the mixer skip. Each batch, therefore, constitutes a
distinct unit and must be handled so that it is kept separate from
other batches. Trucks of various sizes may be used for this work.
The light trucks are usually equipped to haul only one 4-sack batch.
Trucks of larger size, however, may be used by dividing the body
of the truck into compartments separated by swinging transverse

f61.130° 223

34 ULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

doors provided with a locking mechanism so that they can be re- ©
leased separately. (See Fig. 1, Pl. IV.) The number of compart- —

ments will depend upon the size of the batch and the capacity of

a

the truck. For truck haul the proper proportions are obtained by —

the use of measuring hoppers attached to the bins in such a way

that the materials will flow into them by gravity and discharge into —

the trucks by the same process. A measuring hopper should be pro-
vided for each kind of aggregate. Where the aggregates are handled
from a single divided bin it is possible to arrange the measuring
hoppers so that they can both be discharged into the truck at one
operation. This arrangement is much preferable to the use of two
separate and distinct bins for the aggregates, as the time of load-

ing is practically cut in half. After the truck has received its load —

of proportioned aggregate it is driven past the cement house, where
the proper amount of sacked cement is thrown into each compart-
ment. As the truck is turning around on the road preparatory to
backing to the mixer the sacked cement is emptied into the compart-
ments. Where light trucks are used, the sacked cement is sometimes
carried on the truck frame, just back of the driver’s seat, and un-

loaded and emptied into the mixer skip by hand as the truck is dis-

charging. The purpose of hauling the cement to the mixer in sacks
is to avoid any loss occasioned by high winds. In dumping trucks
containing more than one compartment, the dump body is raised
and the end gate released, allowing the first batch to run into the
loading skip. The truck is then run forward sufficiently to give
clearance for the raising of the skip. After the skip is discharged
and lowered the truck backs into position for unloading again and
the first swinging compartment is released for the discharge of the
next batch. With efficient truck operation and a good road to haul
over this method of operation may be successfully employed.

The industrial railway is particularly well adapted for hauling pro-
portioned batches. By this method the materials are hauled in re-
movable car bodies or in batch boxes set directly upon the frame or
platform of the industrial cars, from which they can be lifted by a
suitable hoisting device. (See Fig. 2, Pl. IV.) Greater train
capacity is obtained with batch boxes, and they are the more widely
used than cars with removable bodies. Three general types of batch
boxes are used, distinguished by their method of discharge, as fol-
lows: (1) Tip-over boxes; (2) side-discharge boxes; (3) bottom-
dump boxes. These boxes are generally rectangular in shape and
are constructed either of steel or wood. The wood box has one
important advantage over the steel box; it can be easily repaired in
case of a train wreck, while steel boxes, once they have become bent,
are difficult to straighten. The tip-over box is provided with trun-

PORTLAND CEMENT CONCRETE ROADS. oD

nions, placed below the center of gravity of the load, to which the
lifting yoke attaches. During the lifting the box is prevented from
turning over by a hook attached to the yoke. When the box is in
position te dump, the hook is released and the box turns over on the
trunnions. If the trunnions are properly located very little “ kick
back” is noticeable and the load is rapidly discharged. The side-
discharge box is provided with a false bottom, which slopes toward
the front of the box, where discharge is effected by releasing a hinged
door which usually makes up one-half of the front side of the box.
The side-discharge box throws the material well to the front of the
loading skip, but is somewhat slow of discharge and has a slight
tendency to “kick back.” The sloping bottom necessitates a larger
box and also places the center of gravity of the load higher above the
rail than otherwise. The bottom-dump box is discharged by releas-
ing the 2 hinged doors which constitute the bottom of the box.
This type of box discharges very rapidly and is practically free
from any “kick back.” Batch boxes may be loaded by means of
measuring hoppers attached to the loading bins, but this arrangement
is not necessary, as the box itself serves as a measuring device. The
proper height to which the boxes are to be filled with each material
may be marked by means of thin nailing strips or bolt heads. The
loading plant should be designed so that 4 or more boxes can be
loaded at the same time.

Batch boxes are usually loaded from open bins or a loading tun-
nel. In tunnel loading the industrial train is run under the stored
material and loaded from overhead traps. (See Fig. 2, Pl. VI.)

The tunnel may be partly or wholly excavated into the ground or
it may be constructed of wood on the surface of the ground. The
material in either case is stored over the tunnel This method of
loading permits practically the entire length of train to be loaded
at one time, but it is open to the disadvantage that a considerable
amount of material is required in storage which can not be used
for loading purposes. The material is simply piled over the tunnel
and all of it that lies to the side of the tunnel chutes is practically
dead, so far as loading is concerned, unless it be rehandled. Tun-
nels are rather expensive to construct and this expense does not
seem to be justified when the advantages of the tunnel method are
compared with those of open bins holding two to three trainloads
of material. Open bins with this capacity have successfully loaded
trains where the maximum output with one mixer exceeded 1,200
square yards of pavement, 8 inches thick, per 10-hour day, and
where the average output was well over 900 square yards per day
for weeks at a time. If two mixers are to be operated on a long-
and-short haul basis from one central porportioning plant, rapid

36 BULLETIN 1077, U. 8. DEPARTMENT OF AGRICULTURE.

loading is essential and a tunnel may be desirable, but for a single-
mixer operation open bins are believed to be preferable. Indus-
trial cars may be loaded from open bins either by chutes on the sides
of the bins or by running the cars directly under the bins and
loading from traps. (See Fig. 1, Pl. VI.) After the aggregates are
loaded into the batch boxes the train is run past the cement house,
where the required number of sacks of cement are dumped into the
boxes. The cement house should be provided with a loading plat-
form at approximately the same elevation as the top of the batch
boxes.

A 24-inch gauge is commonly used on industrial railways for
pavement construction and the track is generally laid along one
shoulder of the road. Passing switches are provided where neces-
sary. Both steam and gasoline locomotives are used to furnish trac-
tive power. The limiting factor in industrial railway hauling is
the rate of grade. On sustained grades exceeding 23 per cent the
speed and capacity of trains begins to be measurably reduced. On
a 6 per cent grade the capacity is reduced to approximately one-
fifth of the amount generally hauled on grades of less than 24 per
eent. ‘The capacity on grades may be increased by the use of geared
locomotives, but a locomotive of this type is much slower than a
direct-acting locomotive. The great advantage of industrial railway
hauling les in the fact that the subgrade is not cut up by hauling
over it, and that hauling is affected comparatively little by weather
conditions. The delay on account of bad weather, therefore, is
reduced to a minimum. Another important advantage is that the
aggregates are kept clean and material is not wasted on the subgrade.

Attempts have been made to haul batch boxes on trucks and on
wagon trains, but they have not generally been successful. A der-
rick independent of the mixer is necessary to discharge the boxes
and it has been found that there is not sufficient room on the sub-
grade to maneuver these large machines or wagons without losing a
considerable amount of time.

A combination of batch-box truck haul and industrial railway
haul, however, has proved very satisfactory under certain conditions.
Where the beginning of the pavement is a mile or more from the un-
loading plant and the road from the plant to the work contains
erades as high as 5 or 6 per cent, an all-industrial-railway haul is not
feasible. However, if the road from the plant to the work is in
good hauling condition, trucks may be used to haul batch boxes to
the beginning of the new pavement, where the boxes may be trans-
ferred by means of a portable overhead crane to an industrial railway
train for the rest of the trip to the mixer. The transfer of 4 batch
boxes from a truck to the industrial cars may be effected in from 5 to
7 minutes. (See Fig. 1, Pl. VII.) The pavement in this case is

PORTLAND CEMENT CONCRETE ROADS. 87

begun at the point nearest the unloading plant and as it becomes
sufficiently strong to permit traflic the point of batch-box transfer
is moved ahead on the new pavement.

The principal advantage of this method of hauling is that it permits
the partial use of the industrial railway on work where it could not
otherwise be used, thereby securing so far as possible the advantages
of industrial railway haul. As the point of transfer is moved ahead
an excellent road is made available for a part of the truck haul, and
the wear and tear of the trucks is reduced to a minimum. The in-
creased speed of the trucks on the new pavement over the industrial
trains compensates for the time lost in effecting the transfer of the
boxes from the trucks to the industrial cars. The amount of in-
dustrial railway equipment is reduced to a minimum. Usually not
more than two locomotives and 14 miles of track are required for the
industrial railway feature of this operation.

If the concrete is mixed at the unloading plant and hauled to
the road, trucks are about the only hauling equipment than can be
used satisfactorily. Trucks for this purpose should preferably be
equipped with turn-over dump bodies rather than hoisting dump
bodies. (See Fig. 2, Pl. V.) In hauling, the concrete has a tendency
to compact and stick to the truck body, making the discharge rather
difficult. If hoisting dump bodies are used, a high angle of hoist is
desirable. A comparatively dry concrete is more readily discharged
from trucks than a wet, sloppy mix. It is generally accepted
that concrete mixed at a central plant should be deposited in the
pavement within 30 to 35 minutes after being mixed, though tests
made by the Bureau of Public Roads show that the final placement
may be delayed by as much as three hours without materially affect-
ing the strength of the concrete. This limitation of time necessarily
determines the limit of haul for mixed concrete. Under extremely
favorable conditions mixed concrete may be hauled as far as 6 miles.
The hauling of mixed concrete is particularly advantageous on
work where the supply of water along the road is limited. Its

principal disadvantages are that the subgrade must be used for haul- _

ing and that considerable delays are caused even by moderate rains.
HANDLING AND STORING MATERIALS.

Cement.—Cement for concrete-pavement construction may be pur-
chased either in bulk or in sacks. Bulk cement is not used to any
extent; in fact, its use is practically confined to operations where
proportioned aggregate or mixed concrete is hauled to the road.
Even for this use it is not recommended on account of the difficulty
of measuring the proper quantity of cement for each batch. If it
is used, the proper quantity for each batch should be weighed or
measured by means of separate compartments placed in the batch

eet er Se MEE BS

38 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

boxes. Bulk cement is usually shipped in open-top cars, covered
with tarpaulins for protection from the weather. It may be un-
loaded with a clamshell bucket. Storage for cement should always
be provided at the unloading yard. The storage house should be
leak-proof and should be lined with roofing paper to prevent the
free circulation of air. The floor of the house should be elevated
above the ground. ‘The necessary storage capacity will depend upon
the size of the job and the capacity of the equipment, but for the
average small job of approximately 4 miles, storage capacity should
be provided for about 2,000 barrels of cement. Storage capacity
is especially desirable in case it should be necessary to hold the
cement until tests can be obtained or until the cement has aged suffi-
ciently to pass the soundness test. Where the materials are hauled
to the road separately, the cement may be hauled by any of the
methods previously described for hauling aggregates separately.
With this method of operation, some storage of cement on the road
is desirable. Cement stored on the road should be piled on boards,
or racks, at convenient intervals and shelter should be provided
for use in case of rain.

A ggregate——A number of methods may be employed for handling
the materials into the mixer. Where the aggregates are distributed
on the subgrade they may be handled into the mixer skip by wheel-
barrows or by a belt-conveyor loader as shown in Figure 1, Plate
III. Wheelbarrows are most commonly used, and, where labor is
plentiful and inexpensive, this method will prove economical. The
materials should be distributed in such manner that no unnecessary
labor and time will be consumed in wheeling the materials long dis-
tances to the mixer. The belt-conveyor loader consists essentially
of a long, steel frame, on traction wheels, operated by independent
power, on which low, bottom-dump measuring boxes are placed for
measuring the materials and discharging them upon the belt con-
veyor. A wide continuous belt carries the materials forward to the
loading skip. The principal advantage of the conveyor loader is
that it does away with the wheelers. Its disadvantages are that the
ageregates must be very accurately distributed on the subgrade for
efficient operation, and on roads of average width it is very difficult
to distribute the materials within the area of the subgrade so that
no shoveling of material is necessary in setting the forms.

If the aggregates are stored in small stock piles on the subgrade or
on the shoulders of the road, they are usually picked up by some
form of bucket elevator and loaded in the proper proportions into
batch boxes, light trucks, or carts in which they are hauled to the
mixer and discharged directly into the skip. If batch boxes are
used, they are hauled to the mixer by horse-drawn cars running on

PORTLAND CEMBNT CONCRETE ROADS. 39

short sections of industrial track. (See Fig. 2, Pl. III.) The princi-
pal advantage of this system is that the materials can be placed on
the shoulders of the road before the grading is begun, thereby al-
lowing the teams or trucks to use the road before it is disturbed.

Where materials are delivered to the mixer in batch boxes a derrick
_ is necessary to hoist the boxes from the cars and swing them over
the mixer skip. For this purpose the derrick may either be attached
to the mixer or independent of it. A derrick attached to the mixer
may be operated either by utilizing the power developed by lowering
the skip or by independent power obtained from the mixer. That
which utilizes the power developed by lowering the skip requires
fewer working parts and less power expenditure than any other
method. It is not as flexible, however, as a derrick operated by
independent power and has the disadvantage that the same relative
elevation must be maintained between the track and the subgrade
in order that a constant height of lift may be secured to swing the
boxes free of the cars. There is no particular advantage in using
a derrick independent of the mixer when batch boxes are discharged
into the mixer skip. The added expense of operation does not appear
to be justified. However, for very large mixers, with overhead
charge, a crane independent of the mixer must be used. These mixers
are usually not equipped with traction and therefore depend upon
an autocrane for movement.

Water—The usual sources of water supply are city mains, run-
ning streams, lakes, ponds, or wells. A city main is the most
satisfactory source of supply that can be obtained, as a uniform
pressure is secured and no pump is required. It is seldom, how-
ever, that the work is located so that city water can be used. A
frequent error on the part of engineers and contractors is that
of overestimating the amount of water which can be obtained from
any given stream or pond. Information should be obtained locally
as to dry-season flow before placing dependence on small streams
for water supply.

The most practicable method of delivering water is to pump
it through a pipe line laid along the road. The diameter of the
pipe line should be not less than 2 inches. If very large mixers are
used, a pipe of larger diameter will be necessary in order to ob-
tain sufficient water for curing. Tees for supplying water to the
mixer and for sprinkling should be placed in the pipe line at
intervals of from 200 to 300 feet. Gate valves should be spaced
about 1,000 feet apart and unions about 500 feet apart. Rubber
hose of 14 inch diameter should be used for connecting the pipe
line with the mixer, while 1-inch hose is usually used for sprinkling.
Provision should be made for the expansion of the pipe either

40 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

by providing expansion devices on the pipe line or by “snaking” the
line. For cold-weather construction drain valves should be placed
at all low poimts in order that the pipe may be drained to avoid
damage by freezing.

Either steam or gasoline pumps may be used for supplying water.
The horsepower required to deliver a stated quantity of water at any
given point will depend upon the length and size of the pipe line
and the height the water has to be raised from the source to the
work. A method of computing the horsepower required for the
delivery of different quantities of water is given in the appendix,
page 63. To avoid overloading the pump, a relief valve should be
placed in the pipe line near the pump. This valve should be set
to open when the pump pressure exceeds that needed, and provision
should be made to discharge the water back into the source of supply
so that waste of water will be avoided.

The amount of water required for concrete-pavement construc-
tion is approximately 30 gallons per square yard of pavement. A
4-sack mixer laying an average of 800 square yards of pavement per
10-hour day will require 24,000 gallons of water, or 40 gallons per
minute, for mixing and curing. The failure of the water supply is
responsible for many of the delays in concrete construction. These
delays may be overcome to a marked extent by using double-unit
pumps. The added expense of this type of pumping plant is usually
justified on work of any considerable magnitude.

MIXING AND PLACING.

_ The quantities of all materials entering into the concrete should be
accurately measured before they are placed in the mixer. If wheel-
barrows are used, their capacity should be checked by means of a
1-cubic-foot measuring box. No size of batch should be permitted
which would require fractional sacks of cement. Concrete for pave-
ments should invariably be mixed by means of mechanical mixers.
‘If it is mixed at a central plant and hauled to the road, any satis-
factory type of building mixer may be used. If it is mixed on the
road, a paving mixer provided with traction and equipped with a
device for distributing the concrete will be the most economical to
use. Figure 1, Plate V, shows one type of mixer and a finishing
machine. . Me
The device to convey the concrete from the drum of the mixer to
its place in the road may consist of a bucket and boom attachment
or a chute. The bucket and boom device is believed to be preferable
for pavement work, especially if a relatively dry mix is required. In
chute distribution the tendency is to mix the concrete rather wet so
that it will readily flow down the chute, and this is objectionable

ax

Bulletin 1077, U. S. Dept. of Agriculture. PLATE V.

i

Sea
3
2
:
;
:
e
&
=
s

Fic. |.—MIXING AND FINISHING THE CONCRETE.

Fic. 2.—DUMPING MIXED CONCRETE ON THE ROAD.

PLATE VI.

Bulletin 1077, U. S. Dept. of Agriculture.

Fic. |1.—LOADING BATCH BOXES FROM OPEN BINS.

LOADING TUNNEL FOR BATCH BOXES.

Fia. 2.

PORTLAND CEMENT CONCRETE POADS. 41

_ because the excess of water reduces the strength of the concrete, and
there is a tendency for the mortar to separate from the coarse aggre-
gate.

_ The concrete should be mixed thoroughly to a uniform con-
sistency. The time of mixing bears an important relation to the
_ quality of the output. Generally speaking, the longer the time of
- mixing within practical limits, the greater will be the strength and
the resistance to wear. On the other hand, longer-mixing means re-
duced production and more expensive concrete. The time of mixing
should be long enough to secure the maximum of strength at a
minimum of cost. One minute of mixing appears to meet this con-
dition. Certainly, the time allowed should not be less, and it is
questionable whether the increased strength obtained with a longer
mix justifies the increased expense. To insure the mixing of every
batch for the proper length of time the mixer should be equipped
with an automatic timing device, or a combination timing and lock-
ing device that will prevent its discharge until all the materials have
been mixed together for the minimum time required,

The consistency of the concrete also affects its strength and wear-
ing qualities. For maximum strength and wear, only sufficient water
should be used in mixing to secure a good workable consistency. The
water-measuring tank on the mixer should be used as a means of ob-
taining the proper amount of water for each batch. A test known
as the slump test is employed as a check on the consistency. The
slump test is made by filling a metal form with the concrete to be
tested, tamping it down until all the voids are filled and a slight film
of mortar appears on the surface. The form is then removed and
the vertical settlement or slump is noted as a measure of its con-
sistency. The form may be either a cylinder or a frustum of a cone.
_ Ifa cylinder is used, it is 6 inches in diameter and 12 inches in height.
The settlement or slump in this case should not exceed 2 inches for
proper consistency. If the frustum of a cone is used, the top diame-
ter should be 4 inches, the base diameter 8 inches and the height 12
inches. The slump in this case should be not greater than 1 inch, nor
less than 4 inch for proper consistency. (See Fig. 1, Pl. TX.)

After the concrete has been mixed the required length of time it
should be placed between the side forms to the full-thickness of the
pavement and in successive batches for the entire width. If the sub-
- grade is dusty, it should be sprinkled lightly before the concrete is
placed. Each batch of concrete should be dumped as nearly in place
as practicable and leveled off with shovels. If for any cause a wet
batch or a batch in which portions of the aggregate are separated is
deposited in the road, it should be thinly distributed over the sub-

42 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

grade so that there will be no segregated material in the surface of ©
the pavement. Exceptionally wet batches should be shoveled from —

the subgrade and wasted on the shoulders. 2
FINISHING THE SURFACE.

After the concrete has been spread approximately to the required
cross-section, the finishing operations are begun. These operations —
consist of striking-off and tamping the concrete, and finishing the
surface. Two methods may be employed, viz, hand finishing and —
machine finishing. In hand finishing, each operation must be per-
formed separately, while in machine finishing all operations can be
performed simultaneously. Machine finishing is greatly to be pre-
ferred.

Hand finishing. —The concrete is first struck off with a strike board
having from one-fourth to one-half inch more crown than the fin-
ished crown of the pavement. This allows for a slight amount of
_ settlement when the concrete is compacted. The striking off is ac-
complished by advancing the strike board with a combined longi-
tudinal and crosswise motion. A slight surplus of concrete should
always be maintained ahead of the strike board. The tamping
should be done by means of short, quick, up-and-down strokes of
the tamper, which should have the same crown as the finished road.
The best results are obtained by pivoting one end of the tamper on
the side forms and advancing the other from 2 to 3 feet, at the same
time tamping the area over which the tamper is advanced... This
operation is then repeated by pivoting the tamper on the opposite
form and advancing the end which was first pivoted. As soon as
possible after the concrete has been tamped it should be rolled with
a roller having a smooth, even surface and weighing approximately
three-fourths of a pound per inch of length. The roller should pre-
ferably be 10 inches in diameter, and 6 feet in length and a long
handle or ropes may be provided with which to operate it from the
sides of the pavement. The purpose of rolling is to eliminate slight
inequalities in the surface and remove the surplus water. After the
pavement has been rolled the final finish is obtained by means of a
belt. A 10 or 12 inch canvass or rubber belt is generally used for
this purpose. The belt should be at least 2 feet longer than the
width of the pavement and should be provided with wooden handles
at each end. The first:applcation of the belt should consist of long
strokes with only a slight longitudinal advance at each stroke. A
oreater longitudinal advance and somewhat shorter stroke should be
used for the second belting. The final belting should not be done
until after the water glaze or sheen on the surface disappears. It
should consist of a rapid longitudinal advance with as short a stroke

PORTLAND CEMENT CONCRETE ROADS. 43

as possible. After the final belting the pavement should present a
smooth, uniform surface. Suitable designs for the tools used in the
hand finishing of pavements are shown in Figures 9 and 10. The
small, long-handle float can be used to great advantage in touching

Cover with hose
Se gre us nn a ae HE
Sieg og feb et

a ie WON
= /é See 3 tora! width oF pavemen. Honale
Loard trowng more than section FEQUIFES

DETAILS OF STRIKE BOARD

“

2-2/0 plank

DETAIL OF TAMPER

2x2 angle 2x/2 plank

fi Sen Eres
F 2*6 block
| ‘ “

e-6 ]
Es. /2 ee —— 3 rola! width of pavement eu ELE RLS a

DETAIL OF BRIDGE

a

STRAIGHT EDGE FOR JOINTS

Fic. 9.—Details of tools used in hand finishing.

up rough spots in the pavement when a particle of coarse aggregate
has been dislodged by the belt.

Machine finishing—Machine finishing is accomplished by means
of a power-driven mechanical finishing machine. (See Fig. 2, Pl.

44 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

/ golvonized WOR pipe or 2 22 wood

ve bar /r0N

[ese sas a eee paca eal

A DESIGN GF ROLLER FOR FINISHING

f /1 13 bar iron
/wood heads
soihed rogerher \\\\\\\\i\ 2 3
crossing rhe N\A RA f thick wood block § dra.
Grain. AW,
20nd spike

Cofter pit.

. £ hole trough pipe

eee eel

C. LONG HANDLE FLOAT

‘ } 6. HAND FLOAT
plamaie {1

E. GROOVER FOR JOINTS F. INCH-RADIUS EDGER,
Length 3, width 3; making Length 6, width 4, hasa li turned
U-shaped grooves 2 deep. edge ath a / ‘rads.

Fic, 10.—Details of tools used in hand finishing.

4

PORTLAND CEMENT CONCRETE ROADS. Ad

VII.) The machine is supphed with flanged wheels, which travel
on the side forms used for the pavement. Power for traction and op-
eration is generally furnished by an air-cooled gasoline engine. The
machine is provided with a striking template, a tamper, and a finish-
ing belt so arranged that each may be operated separately, or any
two, or all operated simultaneously. In practice, the striking tem-
plate and tamper, and the tamper and belt are usually operated at
the same time. After the concrete has been roughly spread it is
struck off by means of the striking template. On the second passage
of the machine, the strike board is still in place and the tamper is
placed in operation. The third time over usually only the tamper
is permitted to operate. For the fourth passage both the tamper
and the belt are used. For the final finishing operation either the
belt alone is employed, or the tamper and belt. A common fault
where machine finishing is used is the tendency to let the machine do
a large part of the spreading. The machine was never intended for
this purpose and will not operate satisfactorily if a large amount of
concrete must be pushed ahead of the striking template. Tor best
results not more than 2 inches of excess thickness should be ahead
of the striking template at any one time.

The principal advantages of a finishing machine from the stand-
point of cost are derived from the striking template and the tamper.
These devices replace the usual heavy timber strike board and
tamper, which require from two to four men to operate them. From
an engineering standpoint the machine serves a useful purpose by
making it possible to use a drier and hence a stronger concrete than
it would be possible to use if hand finishing methods were employed.
Its principal disadvantage is that it is not adjustable to various

widths of pavement without providing new trusses, striking template,
and tamper. The objection is not serious, however, in States that
have their road widths well standardized.

From the standpoint of the traveling public the finish of the sur-
face is the most important quality of the pavement. Regardless of
its strength and wear, the traveler invariably judges a pavement by
its riding qualities. A smooth surface should, therefore, be the con-
stant aim. The surface should be frequently tested by means of a
straightedge laid parallel to the center line of the pavement. Va-
riations in the surface of over one-fourth inch in 10 feet should be
corrected before the final belting. The joints are the chief source
of trouble in securing a good surface. High joints can practically
be eliminated by the use of the straight-edge, and its use Is particularly
recommended at joints between sections of concrete laid on different
days. The edges of the pavement and of all joints should be rounded
to about 1-inch radius with an edging tool.

46 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE. :
PROTECTING AND CURING THE CONCRETE.

The quality of the concrete depends to a great extent upon the
conditions under which it is cured. A concrete cured with the proper
amount of moisture has strength and wearing qualities almost twice
as great as the same concrete cured in the open air. Either of the —
following general methods may be used for curing: Covering the
pavement with earth or straw, and keeping this material moist; or
covering the pavement with water. Until the pavement has set
sufficiently hard so that it will not be damaged by walking upon it, it
should be protected with a canvas covering. The canvas covering
may be supported by wooden frames or laid directly on the concrete if
care is taken to avoid marring the surface. (See Fig. 1, Pl. VIIL.)
Under ordinary weather conditions about 24 hours will i required
for the concrete to set sufficiently hard not to be damaged by ee
upon it.

If an earth covering is used it should be at least 2 inches thick
and should cover the edges of the pavement. It should be thoroughly
watered twice each day for a period of 14 days and remain upon the
road for at least 20 days from the time of its application. The earth
for covering is usually obtained from the shoulders or the sides of —
the road. Where earth for covering is difficult to obtain, as for ex-
ample, where the shoulders are composed of hard compacted material,
straw may be used, in which case the covering should be not less
than 4 inches thick after wetting. The principal advantage in the use
of straw is that it can be easily loaded and hauled forward for use
again. In localities where straw can be obtained at small cost it is
believed to be more economical than earth.

The method of curing by covering the pavement with water is
commonly called “ ponding.” (See Fig. 2, Pl. VIII.) The water is
retained on the pavement by earth dams placed across and along the
edges of the pavement. The pavement is then covered with water to
a depth of 2 inches. The water should be maintained on the surface
for a period of not less than 14 days. Flooding is generally done in
the evening when the water is not needed for the mixer. The pond-
ing method is more positive than any other, and should be used wher-
ever possible. It can not be used satisfactorily, however, on grades
in excess of 3 per cent or where the earth available for the dams will
not retain the water.

During the period of curing the roadway should be kept entirely
closed to traffic. If the weather conditions are favorable for rapid
curing, as for example during midsummer, the pavement should be
sufficiently strong to be opened to traffic at the end of 21 days. In
cold weather a longer time should elapse before traffic is permitted
on the pavement.

ae

PORTLAND CEMENT CONCRETE ROADS. AT

When the average temperature is below 50° F. it is better to omit
_ covering and ponding, and sprinkle the pavement only when the con-
_ erete shows signs of drying out too rapidly. Sprinkling night and
| morning will usually be sufficient; it should be omitted altogether
_ when there is danger of freezing.

PLACING CONCRETE IN FREEZING WEATHER.

Concrete pavement construction should not be attempted during
freezing weather. Satisfactory results can not be obtained, and the
| expense of attempting to heat the water, the aggregates, and the fin-
_ ished work is not justified unless only a very short length of pavement
is necessary in order to complete an important piece of work. If
danger of freezing develops after the concrete is laid and before it
has developed a hard set, the pavement should be protected by means
of a heavy layer of straw, covered with canvas. Concrete should not
be placed upon a frozen subgrade, and should not be mixed and placed
when the air temperature is below 35° F.

ORGANIZATION AND EQUIPMENT.

When it is considered that from 50 to 60 per cent of the total cost
of constructing a concrete pavement is chargeable to the equipment
and labor employed in doing the work after the materials are deliv-
ered at the unloading plant, the importance of proper organization,
proper equipment, and economical methods becomes clearly apparent.
Failure to give these features proper consideration may easily result
in adding from 10 to 25 per cent to the cost of a concrete pavement,
and has no doubt frequently caused contractors to sustain a net loss
on projects where profits might have been made.

It is not the province of this bulletin to furnish detailed rules for
the guidance of contractors in planning and executing their work,
but it seems desirable to discuss briefly a few important points which
contractors and engineers in charge of force account work should con-
sider in concrete pavement construction. The points which are of
most importance and to which the discussion will be confined are con-
cerned first with the proper order and progress of the work; second,
the selection of equipment; and, third, the amount of capital necessary
to carry on the work economically.

CRDER AND PROGRESS OF THE WORK.

In constructing a concrete pavement it is especially desirable that
the work of mixing and placing the concrete shall proceed without
unnecessary interruption after it is begun. When the mixer is per-
mitted to stand idle for even a few days, the force of laborers em-
ployed in operating it will usually become more or less disorganized
and a certain amount of loss and unsatisfactory work will generally

AS BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

result when the mixing is resumed. On this account the order and |

progress of the work should ordinarily be planned with the primary

view to keeping the mixer going full time every working day that

the weather will permit. This means that ample provision should be

made for completing the drainage structures, the grading, and the 4

preparation of the subgrade well ahead of the mixer. Provision

should also be made for supplying the mixer with all necessary ma- ;
terials. Where the materials are obtained by rail shipment, and itis _
expected that these shipments will be rather irregular, sufficient ma-_

terial for at least $ to 1 mile of road should be stored on the subgrade
or at the unloading yard before the mixing is started. This material
can be stored with a comparatively small working force, so that an
interruption of their work will not be as costly as a delay to the full
hauling and mixing force.

The small drainage structures should preferably be completed in
advance of the grading in order to obviate the necessity of moving
embankment material the second time. They should always be com-
pleted in advance of the pavement. It is not economical to leave out
a section of the pavement over a small culvert, and this practice
should not be permitted. The extra expense involved in going back
and putting in a section of this kind after the pavement has pro-
gressed a considerable distance ahead is usually considerable and is
often underestimated. This method of doing the work also involves
a delay in opening the road, adds two extra joints, and usually re-
sults in securing an improperly cured pavement over the culvert.

Organizing a force of laborers to operate a paving mixer efficiently
requires considerable skill in handing men. The best results are
generally obtained when a mixer is fully manned and each laborer
is assigned a definite work to perform.

Diagrams showing organization and plant layout for a number of
typical methods employed in concrete pavement construction are
given in Figures 11 to 15, inclusive. These organizations and lay-
outs have been used in actual construction work and have proved
to be.very satisfactory.

EQUIPMENT.

Any discussion of equipment must necessarily be more or less gen-
eral, because the same equipment is not always best suited for each
particular piece of work. Each project possesses certain character-
istics which determine the kind of equipment best adapted for han-
dling it. A contractor may either wait until he has secured a con-
tract before he decides on the type of equipment to purchase or he
may purchase the equipment which he feels will give him the best
satisfaction and only bid on work for which this equipment is suited.

Bulletin 1077, U. S. Dept. of Agriculture. PraATeE Ve

FIG. i.—TRANSFERRING BATCH BOXES FROM TRUCK TO INDUSTRIAL RAILWAY.

FIG. 2.—MECHANICAL FINISHING MACHINE FOR CONCRETE PAVEMENTS.

PLATE VIII.

PROTECTING NEWLY LAID CONCRETE WITH CANVAS STRETCHED ON

Fig. |.

Bulletin 1077, U. S. Dept. of Agriculture.

WOODEN FRAMES

—THE PONDING METHOD OF CURING.

2.

FIG.

49

‘yuomdinbd ModIeq{ooyM “InNoAVT Juvid pue uorjezIULS10 [voIdAT— TTL ‘91

ABYSIUN, BfA19DUOD |

‘SUO/{ IPUOD buidwo, vay 2
anes Japun hop snoy 410 bulyiys usy 2
SNOIAUOUYAISIU PUD S¥10J- S/2AOYC We a spaboa se pais f a4a12U00 buipobeids Loy ¢
SW4O, 19346 O0L OL 0G WoL, bUIfD) LO 4OZf{OSUIO |
adid 1ajom puo duiny 2G0W02 $1 UOUOZIUDHIO Sy | Uowedsly |
113g Burysiuly / BAD AY 4 Of UOILIPPO Ul JaauibUuz Jaxiy |
4a/fo4 Bulysiul, afa42U0) | paplnodd ag PjNoys Yssoa YfIM JUauWad buipuoy Lay 2
saduoy / 2424202 ad bulsaAoo Ge 240621660 ality buipbo vay 2
P1009 AYIA | $ Bue, gee oh Pert 2 ajobasblo auily Buyaaym Ualyy ¢
SMO04109 /22Yf 2/ oN a0ba1bb0 asibvo2 bUIpbo/ Uay £
. 4a/joy Pooy | afbbaibbo as/002 buypeoym Uap 1
AOKI 24942U0D ¥20$-INOY | UDWU2AOY |
LNIWdAINOFT YHOrYW JIYOS SO NOLLNGIYLS/IO
LN3INdINO® anv NOILVZINVYOYO
v1uawe+ 7 14aW/aD ~

000000 W4Oy (2245 Q000000

Geibby, Wie ae

fUIMANDY \~ ee
PHapwoz = ( parbbp asypog
<F

WI0s [2216

H2g

PORTLAND CEMENT CONCRETE ROADS.
SITUOL
PAD OG 2HIL4S

101130°—22——-4

adi JON 2

= " PA eee ag) hs a ae ee ee ne nnn it ~~ 7 pe - o a a ee

‘

BULLETIN 107 , U. S. DEPARTMENT OF AGRICULTURE.

50

[nBy your} ‘ynodvy, JuK{Td puv uopyvziuesio [RoIdAL—' ZT “OW
Buy aod puo
OUND AY DO UO Uy P
bum bf00 & BUA 2409 Uap Of
JOOAOGNS 10 Uj B QU0YIBU! OMY /

SUOMI IL0I Y JOHONL, 4500

Sudo, Uo Vay P BSN0Y S/O{UBPIIU! PUD GUld04 Nop doy Qf 430 API 9) YOM, B 4UBWBAD 40 f9af 108
busily {USUBO 40 UBfy 9 acid dajor pub dingy 008 Y 097 Wor bulhyy ~o a/god02 $1 Uoly~Oz/1UDL1O Sif

pio CupoHds Uj $ SUG {0 UB 2 BUIYIOU BUIYSIUy |
WOW Id — SAOD OWUMIOY/I Udy 2 Afford pooy |

Aaasba BuIKyf / UouW/adt) | SHD09 OUND YJ! SYINAL
SAOLOAIDO YINAL GQ = AO DAB DO Yd IG] | ABH) Bf O4IU0I YODS-ANOY |
YOW3d 07 | Uouladdy { — W009 ff 09 - YIIddap Pakng |

Gvou.NO 30404 ANW1d LV 39404 ]
NOILVZINVOYO LN3WdIN03
Senn

Ud fO/qf b12007. as

Tape a esa I a I a
HON, U1 Ofy Y ¥

HIS
NEADS fae

OL

MENT CONCRETE ROADS.

|
a

PORTLAND C

‘Ney YONI. “SUIXIU ["1}000 ‘{nOART JULIA pue ToOTIezZIURSIO [ROIdAT—'eT ‘DIT

--"
w<—e—o ---
--- — =.
Sy -———_a awe
-—

‘CUOIYIPUDD a/golopnby 4apunN Kop 4NPOY Of

42d api 4324 9/ WY sayIul g suallanod Jo Jaa 10IUI/ OOS oat ee
O/ OS ¢ Wod, buiho yo 290d09 $1 UolOZIUDEIO SIU -: LON _--~~ xe eae 7 ee ener reweaecs 5 ge
SIDJUAPIIL! PUD SU/LOY Ul, add _---~~ ‘sexi U0 Uap 9 7 $0014 9NIDNVHD 40 S3HILINS
aid 13j0f pub dun puo dind 12/00 U0 Uay ¢ vouladl{ { a a-¥ NOILD3S
43//04 Pooy | aposogns Uo Lap Of 410jJ01300 LAX {} / eS
auiyoou buiysiuly 1 Gullajolo pub Bu/4ano2, Uap o/ pays u/juaWlar buipuby
saypog dunp yim syond, g bulysiuy puo buipoasds Uap 9 S42 Ul Uap 2
Luo igoe-4ohanyor jag f / -- Suldof uo Uap ¢ upuats |
woog sng yyl7-yoldiop bal fs ff SHOJOIBDOHINA, G 4lojo1ad0 auDID |
ABXIM PBADUOP HIOGHIG foot |} UOWaIOJ | UDUWaLOY /
IN3WdINOS ‘GVO NO JOYOd INV 1d LY 30404”

\

Jou

BS a ISIDOD
SD :
be
oC

Se

HI/ 4d OG
0A SAMS Ze 6)

eae |
Ay

}
é

BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

52

‘[nvVy [VlaJsnpurL ‘surpvort youun) ‘sutuorjzodoid [R1jyM90 ‘ynokVT Juvild puv UorjezIuesIO [ROIdAT— FT ‘pI
8

suolylouoon xygoioADnf wapluin hop Anoy-of 120 aoim pf 9) ‘Y2IyZ ‘ul Q
fwausarod Jo 4f ui 00g % OG wotf Litho, fo xyodoo $/ Huoljoziubhio siys

auiyoopy DuUIL{S{uly | WNT 2A lio Atiny uo Ly CF S402 Lot
4+aposhgf ig) _/? fuslulaAly bildaA02 Uo 9 fuaiag huipooun UI ;
AAS/OLY POOH | HI0dL UO UIipf & aoyo Li voy / :
APY 2{8419U0Q WIOS 1104 { YboILING plio Silitoy UO LAW Q sul0D LO Luiyo1g Uopy / .
HIOL, (Old {SNPU] S2/IW # SeEsuihLLZ BAL{OLUI0I07 /Oll{SNplLi| p jaunt ll UW 2 -
ALN LOsog-SaX0g Y2OJ OB PHOLD 124 UO HI 2 I9/ffo Lil Low / H
SADQ {Old {SN Pl OF Lotuadls | 3 HOLUSA/S | fs
SPALLOLI0IOT PUI/OSOD AHYOLIAQ SIXIW | — wofolzdag auio4p | :
woog t4 09 Luisi pio Luipoasds uy F juauian buipbof uapyy 9 H
APY |JOYSLUOJI-BUDAD BALZOLUOIOT | UOLUPIIOJ | HOWIAOS fUd/d | H
LN3WdINdy YyorVW\ GvOY NO 32yN04 AINUIg Ly 30Y404 H
{J
a,

-LNSWdINdS GNY NOILWZINWDYO

sbhnob, pz yoo41, /olljsnpuy ft
pays
DAL LOLUODOT

| LLLOg {Def DUiPoo7

(OF 06
fala

‘8-VW NOILDSS

BSS SSS SSS ober Sey AUeSuee aac

5 LT
IUDAD PAIJOLUOIOT Caw

PUNDAH See ae aA ae DMR Mua ai aie ea ara cumaneem ma SS
Q
Q
Q

400g bulpooz7
xobaibbhy

Ss les al es se eft en fe ue et ffeil

bulpis 409 1 XO
ewe

DBRS WOU OSS SUES OUR UB US eo eS BESO PS ee Pe aoe ees Seo ees Ose Oe weseeeee
YIOL, HIOW YY

)

Wen)
[Ney [BIISNpUL “surpeol ulq usdo ‘Surmora0do1d [earjU90 ‘nosey Jud pue uoneziavsio [wordéy— eT 9) Gf
AIOM JO fil 5
piety Bs YjUOW B UbY) atow Jo, hop snoy-g/ 4ed yoI4,, 9 Juallasod
pipe ae J0QL-9/ £0 49a, JOAUI] O05 S340 40 abDIaND UO pios UoljoziUob JO SIY

— ‘
H1OM 40 x x

fl/Ullf Of
SAW §

5/0/UIPIIUI PUO SUIO, 1934S
adid 4ajom puo duns

SU(O1 POOH |

GUIYIOW BUIYSIUITY 7

OXI 84B1DU02 Y2O$ JHO4 |

YIOS] (DIL{SNDU LO SalI S

SIAIYOWIOIOT /OILISHPLU, PUIIOSOD fF
Uu/00G J00% O¢
AIYDND [[PYSUDJI~ BUBIZ Off |

LNIWdINOS YOrVW

ISS Serer SS 3S Ge a ee

@eeaa22a8

(Sse

~
== 6-5: 0-0-8-0- 8:2: 2-2: —

NWNEOILYTS IN/TYO7

7 TEE 477 th uae
Vi p2qg JusuiaD V7 %

PORTLAND CEMENT CONCRETE ROADS.
aso /OOf

BIN) JOAQUIN) ~ SEXO Y2JOJ 0O2/
SIO2 /OlLJSIIPU! OF

ayobaibbhy aury
/ Of

; NIG| XQ
$9)7Y2. Nia >

JUAUBADA BUIIIADD Usp 2) 6,
YIOS)] UO Lay gy
aul) adid UO Lay ¢
aposbgns UO sulsOL LO Lay 9
SIBZUIBUT IALJOWOIOT [OILISNPU/ &
- UDI JOXIW UO Lay ¢
UOWBI4 |
SIOJOIIIQ SAX 2
bulysily puo buiposids vay ¢
UOW 310, |

QvVOY NO 39u04

LNIWdINOZ. GNY NOILVZINVSHO

, O8/

7A ra ere

ajobaibby 2s1009

02 WOlf ju2Wa? BUIPbO/UN Lay ¢
juawa2 buiduinp uay %

SUI Ul Loy |

Uiol) Uo bUIYOIG Uopy |

JSOJOIEAQ IfYD /

SI)NYD JO Uap 72

SID? buiubajD Lay Z

UBUASIY |

sojosadQ 9UBID |

UBW3IOY JUO/A |

LNV1d LV J9yYO4

a0:

pa n
SSS SSS I A eS Se I I SS SSeS SSeS Se

Gy
a

Vea emt | es et refrac | ek in [| | ate a a | |) ie cl | | gs Pr] as | | | aa ef] am aga co

ERS TRE SPER PAPE =r CODY) San ree SPR rf nace Mercadante cn

02 /0£

os) eee pe Wh ee a ey — =

aC is oe 3 ? te
Ds WY SEs hae be 8 LIRER A. Sipe

ne he mer

YIOL, UlOYj~—-A
, 082

54 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

The magnitude of the work should be a guide in purchasing equip-
ment. One 2-sack mixer would be as much out of place on a 10-
mile contract as an 8-sack mixer would be on a 1-mile contract. Con-
sidering the two extremes of too little equipment and too much
equipment, the tendency of contractors, especially those just enter-
ing this class of work, is toward too much equipment. The success
of a contractor upon the completion of any work should be meas-
ured by the amount of money the work has produced, not by the
amount of equipment he has on hand. The aim of the contractor,
therefore, should be to finish the work in the specified time and use
the smallest amount of equipment with which operations can be car-
ried on economically.

The capacity of each piece of equipment purchased should bear
its proper relation to the capacity of the combined equipment in or-
der that all parts may be nicely balanced. A large mixer with a
small unloading plant or poor transportation facilities would be a
poorly balanced equipment on which the contractor would not re-
ceive proper returns in efficiency for his expenditure.

The following list, based upon 1920 prices, will give some idea
of the cost of the various kinds of equipment used in building con-
crete pavements:

Locomotive cranes with clamshells__________ each__ $15, 000. 00 to $20, 000. 00
Automotive cranes with clamshells____________ do___ 6,500.00 to 12,000.00
Derrick: cranes: ‘with: clamsheliss 243-5 Se= do___- 4,500.00 to 6,500. 00
Mixers—4-s4.ck *Capaeéitys 2) 2) oe a ee do_.= *; 6,500: 00; to + 9200000
Road rollers—macadam type_____-__ = do_____- 8, 500.00 to 4,800.00
Industrial locomotives:

ASOT ea oe a a Pe eh ae do_-. . 2,500: 00 to — 4,500: 00

RST Cg tse mR a We AR a SRE Ra ne ie Se eS SR Col FeLi do___ 5,000.00 to 8,000.00
Industrial railway 7Carss = Ae Bas ee eee eee Coes 75. 00: to 90. 00
Industrial railway track, 24-inch gauge___permile__ 4,500.00 to 5,800.00
Industriatepatceh: DOXeS 2. see ee Ea ea each__ 35. 00 to 70. 00
Concrete finishing machines.) 422 eer do_-— +4,1600; 00..to. “2.000208
Sfeclehormges. 225 see 2 ae es per lineal foot__ . 50 to . 60
SUDEACeGMlANeN 0. 27m 82) Pe ee es each=— 400. 00 to 500. 00
VV ACENE Jo UNA ee Se a 2 ee do2s4 600.00 to 1, 000. 00
2-inche wrought-1fon pipes. =) eS per lineal foot__ EEO 25
Tractors, caterpillar, 5-ton__________________each__ 5,500.00 to 6, 500. 00
Trucks, 3-ton capacity, with dump bodies______ do__- | 4.3;000.-00 to. 15, DOGG

The equipment necessary for doing the rough grading and build-
ing culverts in connection with concrete pavement work is not
essentially different from that required for other types of pavements
and needs no particular discussion here.

The total expenditure for equipment for preparing the subgrade
mixing and placing and finishing the concrete depends on the rate
at which it is proposed to carry on the work. Based on 1920 prices
for equipment, a wheelbarrow outfit, consisting of a four-sack mixer,

PORTLAND CEMENT CONCRETE ROADS. 55

finishing machine, road roller, water pump, pipe, forms, and all
other miscellaneous equipment, will cost approximately $18,000, ex-
clusive of the grading, unloading, and hauling equipment. An in-
dustrial railway outfit, consisting of a four-sack mixer, unloading
crane and clamshell bucket, 4 miles of industrial track, 60 industrial

_ cars, 120 batch boxes, 4 gasoline locomotives, road rollers, subgrade

planer, water pump, pipe, forms, and all other miscellaneous equip-
ment, will cost approximately $75,000, exclusive of the grading equip-
ment. The magnitude of this expenditure makes it imperative that
considerable thought should be given to the selection of equipment
and that a well-balanced outfit be secured.

CAPITAL REQUIRED.

The amount of capital required to carry on concrete-pavement
construction depends almost wholly on the size of the project. Asa
general rule, the amount of working capital required after the
equipment has been secured will vary from 5. to 10 per cent of the
total amount of the contract. A small project will require a larger
percentage of working capital than a large one; so that while a
working capital of 10 per cent or over might be required on a com-
paratively small project, a relatively large project can often be
handled with a working capital as low as 5 per cent of the contract
total. The usual method of paying for the work provides for
semimonthly or monthly estimates to the contractor based upon
the amount of work done, from which a nominal percentage is with-
held until the completion of the work. Ordinarily this method
should enable the contractor to meet most of his bills for labor and
materials after the first two or three estimates are paid. The amount
of working capital required also depends to a considerable extent
upon the quantities of materials maintained in storage. Some
storage of materials is nearly always necessary and it is especially
desirable that these materials be stored during the off season. The
storage of a large quantity of materials usually requires an outlay
of capital greater than the average pavement contractor can afford
to make. The buyers of the pavement, however, whether State or
local subdivision, can relieve the contractor of the burden of carry-
ing stored materials by paying for materials delivered and placed
in storage. This policy enables the contractor to secure storage of
materials at the cost of unloading, and by encouraging such storage
the time of completion of the work is generally hastened, benefiting
both the State and the contractor. This policy is recommended.

COST OF CONCRETE PAVEMENTS.

The cost of concrete pavements depends upon the amount of grad-
ing unecessary, the number and size of culverts required, the cost of

56 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURE.

cement and the aggregates, the price and efficiency of labor, and
the nearness of the work to the unloading stations. These factors
are entirely dependent upon the location of the work and are seldom
exactly the same even for two projects in the same locality.

The most satisfactory method of arriving at the probable cost of
a proposed pavement is first to ascertain by survey the amount of
the various kinds of work to be done and the quantities of the ma- _
terials required. An itemized estimate based on these quantities —
and the unit costs which prevail in the community for such work and |

materials may then be made. An intelligent estimate of cost requires
considerable experience and knowledge of construction work. An
estimate prepared without this knowledge represents nothing more
than a blind guess. No attempt will be made to outline the pro-
cedure followed in making estimates of cost, because the subject
can not be handled briefly. Following is the list of items included
in a cost estimate form for one-course concrete pavement construc-
tion suggested by the Wisconsin Highway Commission. A number
of these items frequently are overlooked in preparing estimates.

Item. Operation.

Cost of sidings and moving equip- (a) Hauling and loading mixer, clamshell, pipe, pump, tools,
ment tojob. camp equipment, industrial equipment, teams, trucks, etc.

(6) Freight on above.

(c) Unloading and hauling to job,

(d) Moving overhead (other than rail shipment).

(e) Cost of erection of camp, including water supply, storage bins,
derrick, ete. :

(f{) Return of above equipment to storage. (Note.—Item (f/f) is ap-
plicable only to job requiring whole season for completion or on last
job of season.)

Lost time in moving equipment....Number days ...--- pial sseee per day. (Lost time to include time
lost in transit to job, between jobs, or between different set-ups on
same job.)

Cements. (ee teers. fee eae Number barrels in pavement.

Cost per barrel f. o. b. destination.
Costioie=nass barrels, at ...... per barrel.
Cost of unloading, hauling, and covering.
| Cost of storing and rehandling -....- barrels.
| Insurance on stored cement and empty sacks.
| Sack loss.
Freight return on empty sacks.
Demurrage.

Total cost of cement.

Clamshell and derrick supplies. --.- Fuel, oil, etc., only. (Do not include repairs.)

| Pinte aeeregate’.2-2 820. Number of cubic yards including waste.
| Cost per ton at pit or quarry.
Cost per cubic yard at pit or quarry.
| Freight per ton.
Freight per cubic yard.
Hauling cost per cubie yard.

Estimated demurrage $.......... , divided by total yardage gives cost
per cubic yard.
Cost rehandling from stock pile ...... , divided by total yardage gives

cost per cubie yard.
Total cost per cubic yard on job.

Bulletin 1077, U. S. Dept. of Agriculture. PrATE De

Fic. |.—MEASURING THE CONSISTENCY OF CONCRETE BY THE SLUMP TEST.
Too MuUcH WATER USED IN MIXING THE SPECIMEN AT THE RIGHT.

Fig. 2.—SUPER ELEVATED CURVE BEFORE THE CONSTRUCTION OF THE
SHOULDERS.

Bulletin 1077, U. S. Dept. of Agriculture. PEATE 3

Fic. |1.—A FINISHED CONCRETE PAVEMENT.

FiG. 2.—FAILURE OF A THIN CONCRETE PAVEMENT UNDER HEAVY TRAFFIC.

PORTLAND CEMENT CONCRETE ROADS. 57

Item Operation.

Coarse aggregate..--..------------- Number of cubic yards including waste.
Cost per ton at pit or quarry.
Cost per cubic yard at pit or quarry.
Freight per ton.
Freight per cubic yard.
Hauling cost per cubic yard.
Estimated demurrage $......----. , divided by total yardage givescos
per cubic yard.
Rehandling from stock pile per cubic yard.
Total cost per cubic yard on job.

Wer ep Say -

| - SOE Perey SE Oe eee eee Preparation of subgrade.

iP’ Cost of joint material on job.

Cost of reinforcing metal on job.

Labor, mixing, and placing concrete, including engineer, fireman.
form setters, fine graders, wheelers, shovelers, cement men, pud-
dlers, baling and sorting sacks, curing, covering, uncovering, finish-
ers, water boy, watchmen, pump man, barricades, and lights.

Cost of hauling mixed concrete, including fuel, and depreciation on
hauling equipment.

Water supply and pumping, including labor, connecting pipe. setting
pump, fuel for pump, disconnecting pipe and drilling well.

Mixer supplies, fuel and oil only.

“s Miscellaneous supplies, such as boots, hardware, etc.

CiarepieSS-3 25225. EOL ea te. <2. .. Including loss on board of men on operating days as well as on idle
days, loss on full-time men not included in overhead, etc.
F (Do not include depreciation on camp equipment.)

Miscellaneous costs.....------------ (a) Cost of hiring and shipping in men.
(b) Water rent.
(c) Rent of grounds and buildings.
(d) Cost of building cross-overs.

Gontimrencies ss so oes ee os Delays due to railway embargoes, strikes at pits, quarry, or jobt
material plant breakdown, machinery breakdown, failure of water
supply, unusually bad weather, freezing of pipe line, etc.

Ra PT,
\

Compensation and public ability
TENTED OO ge Set sosc oe ae Fa ce a aa eg eee oe ae

OU GCCOSES SEE eee ore eee Personal or surety bonds.

em Clvenbead 22. 2s 2225-222 288 Per cent manager’s yearly salary.

Per cent yearly salary of stenographer and clerk.

Per cent yearly salary material man and timekeeper.

Per cent yearly expense of manager, including railway fare, hotel
bills, bidding cost, auto, ete.

Per cent yearly office rent.

Per cent yearly office telephone and telegrams

Per cent office supplies, miscellaneous.

Corporation insurance.

Interest on working capital not otherwise includez

Association dues.

Witte... tient. aes + 5 SEES IR ee Bees Ee Pe ee re See ee 0 See

For the benefit of those who may desire to have some idea of the
cost of concrete pavements, a table has been prepared showing the
weighted average cost per square yard and per mile of all Federal-
aid concrete pavements contracted for or constructed in each of the
States during the years 1919 and 1920. The costs per mile are based
on a uniform width of 18 feet. The figures given are for the con-

58 BULLETIN 1077, U. S. DEPARTMENT OF AGRICULTURz.

crete pavement only and do not include the cost of grading, cu!
verts, or bridges. This tabulation is given in the appendix, pages
64 to 66. In considering the costs given in these tables it should —
be borne in mind that the 1920 prices probably represent the peak |
of war prices.

MAINTENANCE.

The shoulders, slopes, and drainage structures of concrete roads
require the same kind of maintenance as those of other types of
improved roads. The maintenance of the pavement consists, for the
most part, in repairing cup holes, cracks, joints, and perhaps the
renewal of an occasional defective area. Cup holes are spots in the
surface of the pavement which break down under traffic and which
may result from a number of causes. The most frequent cause of
such defects is the presence of sticks, lumps of clay, particles of
unsound stone, or other soft material in the aggregates. When cup
holes first appear they are usually from 1 to 2 inches in diameter
and from 4 to 1 inch in depth, but they are gradually enlarged by
the action of traffic, which loosens the concrete around their edges,
and unless promptly repaired they may soon have an area of several
square feet and a considerable depth. The action of traffic also
gradually breaks away the concrete at the edges of cracks and joints,
and if proper maintenance is not provided a considerable area of the
surface of the pavement will be destroyed. The maintenance of
cup holes, cracks, and joints usually consists of filling them with tar
or asphalt and covering the bituminous material with coarse sand,
pea gravel, or stone chips. Satisfactory results can be secured by
this method only when a crew with proper equipment and materials
goes over the road, making the necessary repairs at least once and
preferably twice a year.

Where defects of any considerable size are to be repaired the edges
should be chiseled down until they are approximately vertical and
not less than 1 inch deep. The hole should be thoroughly cleaned
and painted with tar or asphalt, after which it should be filled with
clean, coarse stone chips, thoroughly grouted with tar or asphalt.
The surface of the patch should then be covered with coarse sand,
pea gravel, or fine stone chips. A cold mix of small stone and bitu-
minous material has sometimes been successfully used for this type
of repair work.

Either tar or asphalt may be used for making such repairs. Satis-
factory results have been obtained with each. There is some differ-
ence of opinion among engineers as to just what consistency the tar
should possess in order to give the best results, but the most.general
requirement in this particular seems to be that the tar when sub-
jected to the float test in water at 50° C. will permit the float to sink

PORTLAND CEMENT CONCRETE ROADS. 59

_-n, about 100 seconds. In order to apply a tar of this kind satisfac-

orily, it is necessary that it be heated to about 225° F.

|The repair equipment may consist of a small portable tar kettle,

4 light truck, pouring pots, wire brooms, hammers, and stone chisels.
The tar kettle is usually hauled by attaching it to the rear of the

truck.

When it becomes necessary to renew any portion of the pavement
with concrete, that portion should be entirely closed to traffic, and the
-eoncrete should be mixed, placed, and cured in the same way as a
new pavement. The edges of the old concrete should be thoroughly
cleaned and coated with neat cement mortar before the new concrete
is placed.

A properly constructed concrete pavement ought to wear down uni-
formly and develop few defects. Poorly constructed and poorly
maintained joints are probably responsible for more defects of the
kind described than can be attributed to any other one cause. Tor
this reason the joints should receive very careful attention at the time
of construction.

RESURFACING OLD CONCRETE PAVEMENTS.

Under certain traffic conditions it may be necessary at tmes to
_ resurface old concrete pavements so as to provide an additional thick-
ess of pavement for the increased traffic. The thickness of the
resurfacing layer should be not less than 8 or 4 inches at any point,
and the concrete should be mixed in the proportions of 1:14:3, using
a coarse aggregate graded from } inch to 14 inches in size. Steel re-
inforcement weighing at least 25 pounds per 100 square feet, placed
in the middle of the resurfacing layer, should preferably be used
where the resurfacing is to be 3 inches thick. If the resurfacing
layer is to be 4 inches thick, it is not believed that any reinforcement
is necessary. Where an old concrete pavement is to be resurfaced,
it should be thoroughly cleaned and all the bituminous filling used
to cover cracks and small holes removed. The new concrete is placed
and finished in the manner previously described for concrete pave-
ments. Joints should be provided in the resurfacing layer directly
over those in pavement below. The service records of a number of
resurfaced concrete pavements indicate that it is immaterial whether
or not a bond is secured between the two layers of the concrete.

ae

————

GS

Sie ee wakal, eurricee TOE Prcatt toqeary :
: aot Saad is “en wscther Vie ae Dots

Sia agi

: 64 rane be Yanee: Or Sit 7 si ii “Aawitibags pita rind ;

heibsi ay hs aS gil) ay Ess fis it paras: od: Ra heen saberto 80 l b
oT a TOP ee ish) < ee of Lede Byoe

ides ae e Be iH ‘7 mG Aid TOO, aul de Reritr of bhi Tt Fe

i agile, eg 3 reaitpe ts ED ees UE Panay ay tegal- Ju. BS a ules he
isa od eliried » [st r bt ms notte 245 eal Batts etd ie coe
ser: ie read EDT 1%) aa Bret Cages £ od. I aE hS iti Ag} rit L
Piss ORT Cue Ja vit bir bbl Souk at tt Wold scorns & 6d
ag ines sd Gt pl Jaotin eg A oraite, inG iii oat Wg

hes hey ai , a4 Dee Vi9is ot T: barons eafasil duce Fy inh ra Ab i
Oxeg isi: Wiggers oF hadtguedh “yaar VP RO ALGRAN, rice te nse

:: Bhi: — se Saas Ghee: fn
7 S00 thas & peroosd a: it ioe sas | ga
: oA re a yo o3 Bree siecle eta val coated ogthns Sane Peg -

7 Daisies core ay Tie aa

pee i tie fo a fe ne Atha arth ;

Se

aE Ta ontKa alt Ai Sere a rele | pnts! :
% hi Sguierdhi gif Dist ‘ Hie Sais fife, hee. 2 at a
ae Sats: Wate 3: pb Edson! setionty igeiiay Se Buta:

ee ae Hacaiiaeiaa Sosaus
PPad.. Pa faisiee soe: aot ts

serch Buty Soeeridipatts: floras TIE bY

Ey, ey ee er tine if ss id

2eT A maces ese ON dae: lg WATS BNE oe z

tt fy Cie ts auilsni BOG y sae cua, os Jor ar) one 97 alg

ay fyi A tere as podeni ba od lgat: Pitot beberry, | abe =

Peps i miei) vty) Asay PEs Git} ite Baw Lonuals ay a roth,

lite biasy ‘e eit urine hd ie bahia “gel Dlverts abere
xy dete £2 te alin etx V4 yyy 19 i Morse dion ry He
re dte itor fas racine at Tho be way ‘dloolfisti: eh oeny alg kes ;

get BYsria) oly Lo 218% iG oy} ol aigaetbod fresno ah ds

7” (os

a ee ee a le ee

ras 9” — hr

a oe ee

bbe ae bali alll i

A. QUANTITIES OF

APPENDIX.

MATERIALS REQUIRED FOR CONCRETE PAVE-

1 Quantities given are the theoretical quantities required.

for loss in handling.
2 For pavement on one side of center line, one-way crown.

|

MENTS.
1 4:3 mix.

le Cements sass 1.91 bbls Fine aggregate.... 0’ to 3”

ie Per cabie yard Fine: aggregate - - -40 cu. yd. Coarse aggregate. . 4/1 tO iy!"
ie, Coarse aggregate. - . 81 cu. yd.
Thickness. Area. Quantities per lineal foot.1 Quantities per mile.!
- Width. : 23 '
Per Fine | Coarse} qa Fine | Coarse
Cen- | j; Per Con- Ce- Con- Ce-

Edge.| ter. pean mile. | crete. | ment. a lee crete. | ment. Hane ae
Feet In. | In. |Sq.yds.| Sq. yds.| Cu. yds.| Bbls. | Cu.yds,| Cu. yds.| Cu. yds.| Bobls. | Cu. yds.| Cu. yds.
es ae 6 28} 1.000 | 5,280] 0.204] 0.389} 0.081 0. 165 1,077 2,057 431 872
Oe Zt 2Byle 150000 1g 51280) o20S | 407.1 . 085) 2192.15 1 toe |p 2 147 450 910
Or: 6 6 | 1.000] 5,280 - 167 319 - 067 - 135 881 1, 683 352 713
Deen fe 7 7 1. 000 5 280 . 194 dtl 078 SUG / 1,024 1, 956 410 829
Sas ae 8 8 1.000 | 5,280 + 222 - 424 . 089 . 180 1 2 5 25.2388 469 949
LG eae df She et 5 866 B2om - 453 095 . 192 1, 251 2 389 500 1,013
HO e522 6 6 1.111 | 5,866 . 185 - 393 O74 . 150 977 1, 867 391 792
nO): eee 7 7 1.111 | 5,866 - 216 413 O86 175 1,141 2,179 456 924
HD ee 2 8 8 + 1.11b |* 5, 866 - 247 472 . 099 - 200 1,304 | 2,490 o21 1, 056
NG. fo. 6 8| 1.777] 9,383 | .361| .690| .144| .292| 1,906 | 3,640 762 | 1,544
1G) eee 7 Slee ie Ohass 318 AL? - 151 -306 | 1,997 3, $14 799 1,617
rte | 6 6| 1.777] 9,383] .296] .565 118 | .240| 1,563! 2,985 625 | 1,267
1 ae ae oe 7 z/ The We 95383 . 346 - 661 - 138 . 280 1,827 | 3,489 730 1,480
GE eS 8 Se Laie 95383 . 395 - 154 . 158 . 320 2,086 | 3,984 834 1,689
Le see 6 § | 2.000 | 10,560 - A407 .778 . 163 . 330 2,149 | 4,105 860 1,741
18.. 7 8 | 2.000 | 10,560 - 426 . 814 - 170 . 345 2,249 | 4,295 900 1, 822
ieee 6 6 | 2.000 | 10,560 | .333| .637|- .133] .270] 1,758 | 3,358 703 | 1,424
RES 2 7 7 2.000 | 10,560 - 389 . 743 . 156 solo 2,053 | 3,921 821 1, 663
iG a ae 8 8 | 2.000 | 10,560 444 . 849 178 -360 | 2,344 | 4,477 938 1, 898
A ae tis 6 8 | 2.222 | 11,732 - 453 . 865 181 - 367 2,392.) 4,569 957 1,938
Qe esis 7 8 | 2.222) 11732 -473 . 904 . 189 .383 | 2,498 | 4,771 999 2,023
DOs moc 7 Ca eeDn2O0e aii (Son ereAgoely nh C25 ie a T7aely S50 |> 2228 4 357 912] 1,848
eee 8 Belge Fst MTB I. sedOd en O485 198): 2400) 29608.) 4081. | 1 043), 109
OAS eee 9 9} 2.222 ) 11,732 . 900 1. 061 . 222 -450 | 2,980 | 5,596 1,172 2,373

163325213 ix.
Cementee.-- 26.522 1.74 bbls Fine aggregate.... 0’’ to 4”
Per cubic yard, Fine aggregate.... .49 cu. yd. Coarse aggregate... 1/’ to 2”
Coarse aggregate... .74 cu. yd.

spine 6 28) 1.000} 5,280] 0.204} 0.355 | 0.100] 0.151 1,077 1, 874 528 797
ae 7 [oes le 1000.1. 5;280 | .213 | {370'] 104] 1158 | 1,124) 1,956 551 832
See 6 6 | 1.000] 5,280 - 167 . 290 - 082 ek23 881 1,533 431 652
ie Ss it 7 1.000 | 5,280 . 194 . 338 - 095 . 144 1,024 1, 782 502 758
Uae 8 8 | 1.000} 5,280 . 222 - 300 - 109 . 164 1,172 | 2,039 574 867
ONS SA 7 8} 1.111) 5,866 237 412 . 116 > Wis 1, 251 2,800 613 926
OE Re 6 6} 1.111 | 5,866 . 185 . 322 - O91 stom ie 2) OM 1, 700 479 723
Oe 3 7 Mole be tite} bs 866 . 216 3/6 - 106 -160 | 1,141 1,985 559 844
sae 23 8 8} 1.111 | 5,866 . 247 - 430 - 121 . 183 1,304 | 2,269 639 965
1 ee eee 6 8}. 1.777} 9,383 . 361 - 628 Auygi7/ . 267 1,906 | 3,316 934 1,410
Lh eee 7 8 | 1.777 | 9,383 .378 - 652 - 185 -280 | 1,997 | 3,475 979 1,478
aoe eee 6 Saleen te 9 383 . 296 - 516 . 145 . 219 1,563 | 2,720 766 1A ksy
BGR if 7 iN eats . 346 - 602 . 169 . 256 1,827 | 3,179 895 1,352
Geet SS 8 See Ai 95383 . 395 . 687 . 194 292 | 2,086 } 3,629 1,022 1, 544
eee ee 6 8 | 2.000 | 10,560 . 407 . 709 . 200 . 301 2, 149) {= 35739 1,053 1,590
RE Fa 3 7 8 | 2.000 | 10, 560 - 426 - 741 . 209 315 | 2,249} 3,913 | 1,102 1,664
BS! Seo 2 6 6 | 2.000 | 10, 560 000 - 580 . 163 247 |} 1,758} 3,059 861 1, 301
SE 2 7 7 | 2.000 | 10,560 - 389 - 677 191 -288 | 2,053} 3,572 | 1,006 1,519
MS tes. 8 8 | 2.000 | 10,560 . 444 773 . 218 329 | 2,344] 4,078 | 1,148 1,735
ee 6 BAP De ws) | F458) aR 199%] 385 [142,392 |C 4 162°) 1,172'| 1,770
AV Ss ee 7 8 | 2.222) |. 11, 732 473 - 823 - 232 300 | 2,498} 4,346} 1,224 1,849
74 | eee 7 Ue ERP abl ey) . 432 . 752 . 212 320 | 2,281 | 3,969) 14,118 1,688
74 ie ee 8 She ze2e2 | 11, 732 . 494 . 859 . 242 .365 | 2,608 | 4,537 | 1,278 1,930
PORE Lee 9 9°} 2..222)} 11,732 . 900 - 967 APTA A411 | 2,930} 5,098] 1,436 2, 168

61

In actual practice an allowance must be made

62 APPENDIX.

A. QUANTITIES OF MATERIALS REQUIRED FOR CONCRETE PAVE- eI
MENTS—Continued. |

132) 2 oe

Cement. 1.61 bbls. Fine aggregate....0’’ to 177
Per cubic yard, Fine aggregate.... .45 cu. yd. Coarse aggregate. -1’’ to 21”
Coarse aggregate.. .79 cu. yd. |
Thickness. Area. Quantities per lineal foot.1 Quantities per mile.t
Width. | Pan = oe ae
Gens | Per ShaGon= Ce- ee Pane seed eT Nye Ce- net) oe
Edge linear P aggre- | aggre- agere- | aggre-
ter rae | Inile crete. | ment. gate. gate. crete. | ment. gate gate

__—$—— | —_j ue | _ ———

Feet. | In. | In. |Sq.yds.| Sg. yds.| Cu. yds.) Bbls. | Cu. yds.| Cu.yds.| Cu. yds.; Bbls. | Cu. yds.) Cu. yds.
850

secs. 6 28) 41.000] 5,280) 0.204] 0.328] 0.092] 0.161 | 1,077} 1,734 484
Orr! 7 28 | 1.000] 5,280 . 213 . 343 - 096 .168 | 1,124] 1,809 506 | 888
ee: 6 6 | 1.000] 5,280 . 167 - 268 .075 - 132 881 1,418 396 | 696
OR sess it 7 | 1.000} 5,280 A94 yolZ . 087 .153 | 1,024 | 1,648 461 809
ee 8 8 | 1.000} 5,280 . 222 . 307 . 100 Pho: (Se hret |e ASST 527 | 926
1Qe 2 7 8 | 1.111 | 5,866 AIRY) . 381 . 107 - 187 | 1, 251° |'.2,014 563 988
IOs 23 6 6| 1.111} 5,866 185 . 298 . 083 . 146 iis Ge: 440 772
Lee ee 7 7} 1.111 | 5,866 - 216 . 348 - 097 SLL 1,141 1, 837 513 901
HOST 8 8 |. 1.111 | 5,866 . 247 . 398 ait | -195 | 1,304 | 2,099 587 | 1,030
GES 6 Selle did ed ose . 361 S5SIet 5 F162 -285 | 1,906 | 3,069 858 | 1,506
NG Se x4 7 8| 1.777 | 9,383 .378 -609:} :170 .299 | 1,997 | 3,215 899 | 1,577
1 eeseeee 6 Gils LLG |t 95383 . 296 477°; =. 138 . 234 | 1,563 | 2,516 704 | 1,235
165.2! 7 We le Leaee I 95383 346 2550 | 156 .273 | 1,827) 2,941 822} 1,448
Go 2 8 Sie Livi |" 95383 395 . 636 178 -312 | 2,086 |. 3,358 938 1, 647
SESS. 8 6 8} 2.000 | 10,560 407 655 183 322 | 2,149} 3,460 967 1, 698
Lae See 7 8; 2.000 | 10,560 . 426 . 686 192 .336 ; 2,249 | 3,620} 1,012 1,776
he ae 6 6 | 2.000 | 10,560} .333 536 150 | .263| 1,758] 2,880 791 | 1,389
ieee oe 7 .7 | 2.000 | 10, 560 389 626 175 2307 | 25053 |* 3:)305 923 1, 621
ie Same 8 8 | 2.000 | 10, 560 . 444 715 200 .30l | 2,344] 3,773 | 1,055 1, 852
741) eee 6 8 |) 25222 | 11; 732 - 453 729 204 -308 | 2,392 | 3,851 1,076 1, 889
71 ee a 8 | 22222 | 11, 732 473 762 213 3/4 | 2,498 | 4,022] 1,124 1,974
20 ae = 7 @ | 2.222) | 11, 732 432 696 194 . 341 2,281 | 3,673 | 1,026 1, 802
71) ae eee 8 8 | 2.222 | 11, 732 494 795 222 -390 | 2,608} 4,199 | 1,173 2, 060
7) eBay 9 9} 2.222 | 11, 732 50d 894 250 -438 | 2,930 | 4,717 | 1,318 2,314
Mis 2se4y Mix.
Cementienecs ace oe - 1.50 bbls. Fine aggregate....0’’ to 1’
Per cubic yard4 “ine aggregate.... .42 cu. yd. Coarse aggregate. .4’’ to 2}’’
Coarse aggregate.. .84 cu. yd.
|
Qenaecte 6 28) 1.000} 5,280) 0.204} 0.306] 0.086} 0.172] 1,077 | 1,615 452 904
Tyee ae Z| 28") 1/0009] 25,280" |" 213. |. 319 1" L088 S178 ods ea eeaeeRe 472 944
GE sos! 6 | 6; 1.000] 5.280 SLOW . 250 - 070 - 149 S81 1,321 370 740
eee 7 7} 1.000} 5,280 .194 . 291 - 082 164 | 1,024] 1,536 430 860
Ue aeee 8 8 | 1.600} 5,280 «222 . 330 093 186 1,172 | 1,758 492 984
LORS. i 8| 1.111 | 5,866 2257 . 399 099 198 | 1,251 1, 876 525 1,050
AOE Se 6 | 6} 1.111 | 5,866 . 185 . 278 078 156 | 977 | 1,466 410 820
\ eee 7 | 7}. 1.111 |) 5,866 . 216 . 324 091 182) 1, 140s IA 479 958
OES Ss 8 8} 1.111} 5,866 . 247 . 370 104 208 | 1,304 | 1,956 548 1, 096
AGH 34 6 8 | 1.777 | 9,383 . 361 541 ~152 304 | 1,906] 2,859 801 1, 602
LO. 4-3 7 8 | 1.777) 9,383 . 378 567 . 159 -318 | 1,997 | 2,995 839 1, 67
eae 6 6| 1.777 | 9,383 . 296 . 444 . 124 -248 | 1,563 | 2,345 657 1,314
MG. Foe 3 7 CONF Sa WR Re . 346 519 . 145 290 | 1,827 | 2,741 767 1, 534
ee 8 SP Lanideik, 95380 . 395 593 . 165 .332 | 2,086 | 3,129 876 1, 752
lke oe cee 6 8 | 2.000 | 10,560 - 407 611 ely -342 | 2,149 | 3,224 903 1, 806
(ae 7 8 | 2.000 | 10,560 - 426 639 .179 -308 | 2,249 | 3,373 945 1, 890
ARE Ge 5 6 6 | 2.000 | 10,560 5838: 500 . 140 -280 | 1,758 | 2,637 738 1, 476
Le ee 7 7 | 2.000 | 10, 560 . 389 583 . 163 -326 | 2,053 | 3,079 862 1, 724
1 te See 8 8 | 2.000 | 10,560 . 444 667 . 187 374 | 2,344] 3,516 984 1, 968
7 e ee 6 Siig 2e22e elle 732 . 453 679 . 190 -380 | 2,392} 3,588] 1,004 2, 008
2 ae 7 S |i) 251222) 11) 732 . 473 710 . 198 -396 | 2,498 | 3,747] 1,049 2, 098
NE Re 7 | | 2, 222 OU 482 432 648 . 181 .362 | 2,281 | 3,421 958 1,916
OO. 2 3 8 8 | 2.222 } 11; 732 494 741 . 207 414 | 2,608 | 3,912] 1,095 2,190
ZOE Fs 2 9 | 9} 2.222 | 11, 732 | 555 833 . 233 466 | 2,930} 4,395 | 1,281 2,462
|

! Quantities given are the theoretical quantities required. In actual practice an allowance must be made
for loss in handling.
2 For pavement on one side of center line, one-way crown.

OR

APPENDIX. 63

iz. TABLES FOR DETERMINING THE SIZE OF PUMP REQUIRED FOR

DELIVERING WATER.*

Loss in Friction Head.

Friction head in 2-inch pipe—

Water required per minute. ;
1 mile. | 2 miles. | 3 miles. | 4 miles.

Feet Feet. Feet Feet.
EY EERO Y ING sp SS a at See a = 51 102 153 204
| BASE ECE as Dee eae Pere haat e oe ence nee 110 220 33 440
PUCCIO TI Ge at pete pS Seon fh tes ae, AN BG ele. cba ok Se 194 388 582 776
AD SOLOS Sees Se i eR ee ee ees ete a 296 592 888 1,184
BBs H LOFTS eis rete eee Pe hen een Sey ies ae ome le ; 468 936 1, 404 1, 872

1 From anarticle by Clyde E. Learned, Highway Engineer, Bureau of Public Roads, published in Publie

_ Roads, June, 1919.

[or 4

To the loss in head in the above table it will be necessary to add the
vertical height that the water is to be pumped and to make allowance for
angles and valves.

The theoretical horsepower required to furnish water under different heads

vis given in the following table:

Theoretical Horsepower Required.

Total head.!

Water required per minute.
109 209 300 400 500 600
; feet. feet. feet. feet. feet. feet.
Horse- Horse- Horse- Horse- Horse- Horse-
power. power. | power. power. | power. power.
PANO DL OLIS Eee ee ga en eal gn Bas oe 0. 50 1.00 1.50 2. 00 2. 50 3. 00
BORMAN OHS Ree ee ee ek tea teen ek 0. 75 1.50 2, 29 3. 00 3.75 4. 50
A eoa ON Seae ee he Seep seek ee eee 1.00 2. 00 3. 00 4,00 5. 00 6. 00
FD Res Ty ee re akg a gee are | 1. 25 2.50 3. 75 5. 00 6. 25 | 7.50
BRAN OUSP tac. See. pone Se cee tres) | 1.50 3. 00 4. 50 6. 00 7.50 9. 00

5. Total head required equals friction head, plus height to be raised, plus loss of head in valves, elbows,
etc.

Multiply the theoretical horsepower by 4 for deliveries of 30 gallons per
minute or less and by 3 for deliveries of from 30 to 125 gallons per minute.

EHxample.—Required, 40 gallons per minute; maximum distance to be
pumped, 2 miles up a hill 100 feet in height.

From first table: Feet.
LEGS TED SEE ZIG hs SVCISS Onl Of eng 6 = ak eee a ae eRe 388

OS eG eS exzal 2) PRT Ta a SUS Oa ee ee 100
Estimated loss of head in valves, elbows, etec_________________ 20
ERPS Th Sve C6 [Tk RS SENS toe a a Se ie ieee ie RY a 508

From second table: Horsepower

Theoretical horsepower required
Actual horsepower required for engine and pump, three times
epee ea bellonrsepower ee 4 1b ts eR Se 15

APPENDIX.

64

Cor ‘og G09 "5% te seeseeessegcorMomyy ULOJTUN ,,9

969 ‘OF CCINBG eI Lt ee ee Ope

119 ‘9% nese s Ceo °c CeR DOR 0 LOMO: 1,8
096 ‘98 See e Ea cor eee vee rea RRO TOM ULIOM UL, |e
¢ ig wececceserceee é‘
SZS ZE O8P 8T sos po 149 ‘103000 4,8
PLS ‘TE wretestese|scsssrs ss sss *saspa ,,9 (101 U9 4,48
eor Fe = | Gare |777777777 7718089 ,,49 ‘50100 ,,f2
808 ‘CE 006% | 7771777777 80BDO ,,9 ‘109U0d ,,8
ers 3 I OOL 5oe A ay ieceigehaa ea iter ee
CPL ‘FE C16 ‘77777 SOBpe ,,g ‘10409 , 8
ae6‘o | POL'GG 7177777777 TT OBO ,,g ‘109 U9 ,/#2
FLY ‘62 206 FZ «I-77 *SE8P9 ,,9 61041109 ,,8

69S ‘ST i771 sespe ,,2 ‘10990 6 | FE: ZiT
“fe Ea ora ag an "7771 s0Rpe ,,9 ‘10090 {8 | FE: ZiT

ae alld cama

910 ‘sé Tp 0 | 7 77777777 78E8Pe ,,9 *409U0d ,,8 | FE: :T

Besesseren! Oop gn [ott te

GPS ‘ZE LIL ‘9G |" 777777777 *SSOUHOTY} UrsojTuN ,,8 | $E

apeeR, oe | oT|en a5 be S8S pe FG: s09t100:,,£0

089 ‘TE “Sie saa bias) fh ec at dem ea ae Te Ra ae Oe
LSE “6z omnis ns goonies SAHOO TOTUd:,)9
Ages le PS AGIs ISSN Ney} OC Ae iced Usa) jy

EET ‘GZ x yu eee ics oe eee Be aiaaies oe RODE Sic,

Q0p ogo lee ese) ee SOspe 7,G ‘107 TI00 |)

Capra | See R a9 aPI 00 fd
Ge ssouxoryy UIIOJTUN 4/49
ide) tc Ra |e Si an peep

‘ ataiwtatatete nia isi |(eiata)ainie SOCIO
GLP ‘€8 ore [pra "777 “SsOUYOTY} ULIOJTUN ,,9
CON Ta htt ae SoZ po ,,G ‘10990 ,,9 | _
esos or ofc Bick Beeb se bay RR

PE6 ‘82 eee
STS ‘0k 909 ‘9%
gee ap" ERT 96
OLT ‘0S | OFS LT
Co eats S 089 TE
199 ‘ez | - FoF ‘LTS

OZ6T 6161

*MOT}00S-SSOI)

*sootid esouy
uo peseq ‘ATUO
{USTIOACA 4OOJ-8T

IO} oytur 10d 4s09 OZ6T

nia
HINANNANANANANAIAN

Cn An oe rs cee ee ce ee ee

Ce
.

eH SH OD OD SH SH LD OD <H OD 0

eh “cS

QDOnwne
RSSSSB3
CON Od Od Nod od

09 °E
ass

£60 °€

00°§
8L°%
Sh G
8E°S
0S °G
8h G
83 °S
18%
LIS
06°

FL‘G
68 °G

“paved
eienbs
rod oo1d
OSVIOAY

“47mMq 10
popreaMe

stresses cco yOrg) UIOJIUN ,,9
Sinwieecivceeene sospo ms) ‘10409 18

sieiniwie'¢iehnle nim ---sespo 9 £10199 ,,8
ASSOC O90DGS sespe ,,#9 ‘109000 ,,F1
Concise O SOLO aUMOO 778
Presses" 6930 , 0 “1000 FR

RASS Sie ks = = AGE
nein h rk * o's > “ORICON
Buns saw encelenendcsecnaens Tega teers * as Toi TT

od PP ee eee re

ot CLT 916 ‘E9 “igs A= => CMO RST ET
SE RIEG s ee eC ee at a ae oa ee ESTES
Zt | 28% CTL ‘OFL morrees ss ** "BI OSOUUT
98% 68 066 Totcrresoos ==" TBS TOT
FPG FFL 6L Riiag:. OS a ater d 0G |

I

I
fag "7" 7 *ssouyoTy WOIJTUN 9 Te | Liew =, peiesag ag. ae opie
eae at *-="-s98pe ,,¢ ‘104U00 ,,¢2 Zo i rd Z£0 ‘CLT (TSS sesngoesseyy
cial aeidele ---sespo ,,9 ‘10909 ,,8 2:1 98 °% 098 “299 Trrrrstts ss puepArey
Ps, Re eee PF na OOO Le OIC Cd Cd ed oi ew eee CL O®>
seegdeeoae cde ageanenteivcitnaee reel gay vey eawal pepe eae ee ase res oe a eo Set 00
JOOS hyo Sistine cinsine TOD ee ge weasel £9 °Z FEE ‘L9 eee a
Dees Gk eee Se ee ODe tel orca 88% GE9 69T ©) a Hey oe pRee UL
se ianon take --sa8po ,,9 ‘104U09 , 8 69 °% 16 962 1 ie 3 ey 0 BOT
"Teor osto sess sse8pe ,,2 ‘1091180 8 || § &o % LOOeCOG STS. "|e ay ee ae a sfouTtit

oe Doe PSM S| denies Goes ante Slo pee came sn eae oyepy

Se aciace ad aa AE i aad SaneA SN, ee ee mee” aed lee RTC |r meee gal toda genie erin te |Weerer. ce gat ot eae ae al 0) @ |
nats wre Sieur! Se een en meet ae |e ir came a ee ipo eek ae ee |e eats Pp: OG
PTO TO ie RT el a ea Oke on, Gc eal ok se ge oad ba eae eae co |iey Paley ane = ge Sen IRE EOC,
Foe ee ae 0 ae vecteteee tees eecee|eseeenecee[oee ee eecec|eeeeeenecesere|eeecsereeesseegs
De eae a Bh cree todas araic te ome [Syme steers seme | ee cries oa rcteeeesecec ee [pees ee ee ec ee eeee od
CN Aa ade eee Bota ait tadetes Soe: Meme ake |i Acie aa] |) Fe, er ree Poe 2. Scie A | ae Se ee? Me rors eo OLA |
eT es ate Barer yee See ee aie a Pataca Tale |= patie it ey lie Pid ane mete a, S| ae ae i oe OT GE
Ppa ON Ree ei aA! DA a ree re MT eee Sook | ee oe ee nies \| by ey RN ae mE Cl
ah aE Set CS SRR Ce Se ee ee ew yee 7 eae ana sl ge ee tee whe ee gS “-""" BIZI004)
Sood ai du --""se8po ,,9 ‘1091190 ,,8 =n ZAT 1Z°¢ Zz9 “E9 gents 54 (et ~ SISO BIO
ee ora PR asda yo aP eT oa eee ea 2 rk | ae ae Gis 4a ie aceite Pr wi we || ae a ae “qnorjo9sUUud*y
eer “77 *"""s93po ,,9 {10}U09 ,,F) : BT 1S % 88 FIT 7) SL ae PBIOTeD)
Lana **ssouRjoryy UAIOJTUN ,,9 Z:1 | 8% O09L ‘ELT Pa aaa ase
aie aibisi=isie >= “SsoUMOTy} ULIOJTUN ,F ZiT 69 I O10 ‘FIF Sale ey SIONS
te O19 “**"s93po ,,1 {10]T90 ,/8 ite) OOKE 86I ‘18 ile eee chr ESN EY
sierceecle "- > *ssoUMOTy} WAOJTUN , -G ST | So'1$ | OIF ‘Ty gee a ROAR:
‘sph bg
“pIvaA +
tx eae HN |
*M01}00S-SSOIQ XIW | god coud | 1° PepreMe |
eseoay | PBTPIOL | 24819
6161

*SJUDUIDAR 9}019U0D Ule[d

‘SLNGWAHAVd ALAYONOO GIV-IVYUACHH AO LSOO DO

65

4
TOL ‘08 LST ‘9 cot? Drees ae MSAD OCIS ay ‘oyedo133R dAvI3- :
bd $29 ‘oe Be. - SUOT}OOS [TV |SOXTULITV| E16 °% ZLG ‘egg (glecceetetec: ir < : pues poulquLoy |
NE ES pepicae 5 cane er a PE Sa iecomeee eae nk cee be SU01}008
a OF0 “62 LEY TZ OC SE Si seabed ‘10} 009 ul (38 Go| 06 °% 006 FI ere Shae 4 ITV |SOXTOLTILY| LL °% L9G ‘eT ‘oy
A 60T ‘FE 3) C88 '62 SS anc TANS °F | BEE DS ike Rea a eaA8 Fe: G1 CLS 166 ‘269 __ Pied BS eee BES a ete lO
BECHEGE ile cta cr. PS IT . ei eG Gil = Weta otal AEC LO eT oe ce Ssospo ‘104 ir. Sagefalck Rip pole Apel ae lLLy sae =:
3 OOP ‘9G at ue Tel Ta eae ta“ seas 119 ‘104099 138 e:4Lit ez 'E NC is Bil hot ks tals oop ste "6: oT £0°S 166 ‘T¢9 9 Sp re "77 -BuruTOd MA
Ay P92 '£€ ee Soba fp ee ak eae eae) aenuee with (oS Go| (je % 668 a Soke a ions ie sodpo me) ‘19400 «8 on ae €8°S CEP TOL Bee Bite.» ne U TISUOOST
«a 6IF CE 226 is sOOn mote Ie i cede Hh) pe Sh) Ty Np Yoo cL '¢ Veh 21? pa ng Nevaeh sodpo ,.9 ‘104199 ¢) ue co C&G Ply PORE tlk eee eIurs oe
en | hdc h Sy eae Magn aS ep eRe ng) MOUUSO Lye ceT || 720 “e ee eee AES eagles ope ae ey aera ie €: 3:1 | 667% 626808 tn SGA 480A
eee ae paler au Scape li ee Saale ono signe COURT Oya Ie Teor “===> =s08po ,,¢ ‘ iaeet lit eae oe[eeevetteree. ages aueie! 1USBA\
096 ‘98 DAGKORN) oe ee fl FIGHTS eee: ea Gua Rn: Fog Shee uA eapaanis b: G1 | 98° zee ‘TOL s¥dit tn shee ee
eens Pape. n\ seer ee SOBpo ,,9 ‘10}U09 ,,4L | €: ST | 0G"€ BE aw ae Sees oe Tend MYR apres @enes| C232 9s ORG) rie am streamers ay
DRO ties |pee-a2 2 Sas acpgainn” Gia ee 7: sei |ASOlg Ur eae wt een ee ~t=Sogpo.//2 | gb) ase aleroen ele acre e a. Bie
¥29 “08 ‘a6 Be wettest eee Sespo ,,G 109U99 , ay ae ae & 6LP ‘88 ae ae See is ffs (79499 8 E: 6:1 G8 °z Ghee ee ot |sacae eeeeee “yea,
Le CTE ‘ST ae epee ete i Sregebe | 06 : Boia ab a "7777" "sad po “a 104109 a ue Se fan % ooc{201. 0 ttt ae
iss in eile a3 Margen’ gtlaninas Sai Aries a fc ak Se CO) 8) 2 EL a Bae saspo i “ oar % Tcl |t-ss* poate: a ae da
192 ‘62 ae ie CREDO OIC sespo ,,9 ‘104000 , y: 6Z" ‘ideal |e. SADT Se eee) ese08 2 ee: g: 6:1 CZ Nee per Ps eee SUXO],
PE6 (82 CRN IOC OIL TEI Cabal eal SO8po , 9 £10} 009 48 GH om € ATELIER lh oleae Sa8po- & ‘1941100 8 | ¥: oT CHT 7a a ee dassouue L,
zer‘oe | ocr ‘ez soci soap 10}100 ,,49 | €: ei alee aida iabiehaes ere cdi ae en eaealane ears T2 Ole Hes eee 225+ euToreg I
ise cia| ee see err ee cre | 9201 Se Ee reas na Samergo vanes
Da! 2 aad Sed cee ee . sabecaheeRes ee ao) bia eT Sie Boats sh tae © #9 (19100 ,/f8 =f oe OH TF’ ‘ ee ae Chik ae u03010)
2 0&2 (08 UPON ONE CHA FO CIO 0 ® ,,8 19999 ,,OT of P40, G COTM OR ena Se cat e
asia BL8 (LZ 5 Pees Seen creseesee gg po , 2 {1041109 , eFniT 80°E #10 ‘29 we ee EOOU SEG
CHS "ce OFT (62 win aeetethe Sindee ones cee tree Ss sospo ,,¥9 {104190 nts ete 2 egtTee 0 frttcttctct de
serie ea OaeG eS Sete eR wate e eee eee ies ‘ BN ge aetieioveaig: sei heats PROD ean dae i GRTAGOT ee ee es ee
Sg ae eae pep eas | a een S| ERED espe gsi. | EEE | oe |G! un eters
WI 060 e pac aweeeesec isha Bae PE Ge Ns AGE is Pate "77 s08po ,¢ ‘1o]U0d 2 | E4T:T | F2'S | 288 ee raat acts
1 GP OT ee seee a OD Bat Ae Gy Nc shee olf Eee pets Wa tts heh os) 6 F Ry ne ee end ence
198 ‘ge Ite fe Se eT 2 Sespe 8 “10}U00 X01 ee es " 129 ‘81 nid aT Mw ew ain an ceed aeanaies &! 3:1 PLS 120 ‘S21 “TTT TT OOFKOTT 40 NT
96L'28 | OBZ | ce erat eMMeR TES | GB 8 ily io eee eee 2) ye eRe epee ean oy Mea EE ig vdecese sae
8 e410: OL’s 998 ‘Sb ST Sees Mine oppuni armen @: ZiT ae Tha ea oe ean
7) 1941109 8 e:Etit I€ ‘% Sor Th Petey ulate
“> * "AGSIOL MON

J

sedpo ,,9 ‘1090199 ,,

5

101130°—22-

ee

4
bH
a
7,
&
Ay
ath
a

66

VOL “FE BBBWAG = i to “SUOTJOOS [PV fo SOXTUE ITV | 262 °€ (RANA = ee SS Sikh SUOT}OOS TTY |" "> SOXTUL TLV
Bae pes" GUL OG Si a iaes aaa Spe hgigae e|, go ook ole lem ed SOdPo ,,2 '107W99 ,,28 Lit 6:1
186 (LG 628 (8% |“ Sespe ,,¥9 “109109 ,,F2 | 9: E:1 | €: BT | $9°% GLB 'SST |" SeSpd ,,9 “19} 009 ,, ZL tL:7 ¥E:1
910 (Se 070 62 _|-- -SeB8pe ,,£4 ‘107109 6 | G: E:T | €: oT | 09'¢ STL ‘02 "7 S0spo ,,9 ‘S10JU0D 8 | G: E:T | &: BT
GLONGE eae p77 80Bpe ,,2 “10900 148 | F:F2:1 | ¥o:41:T | OL'E DLO es dk P|, ane gece ae | ge Oe e
LLZ “LE PE6 86 |" "Sespo ,,9 ‘409U90 8 | F:¥0:T | Fo:FT:T | ese OFO ‘ge =f *sespe ,,9 ‘1eyU0D = g | F:FS:T | H:ELT
Sa (S481 ies Wiaae RE ee SF ee eee eee Be ae eer ge oa sospe ,,9 “10JU90 2 | 9: E:T | ST
LIL 908 | 90S “9B |“ ~ “SeBpe ,,9 “10}T109 ,,2.| 9: S11 | SI SE | EG'zs | 002 Et ““ssoUyoryy UIOFTUN ,,9 | 9: E:T | ES! BT
“sph “bg
OZ6T 6161 oseg doy, : pie -y[mq_ 10 aseg doy,
“MLOIJOOS-SSOIO) sod ootd | PePreae *UWOTJIES-SSOIN a
“seormd oso} XT aseroay | VOT? 1P0.L “XT
uo poeseq—<Ayuo
JUSTIOABA 4100J-8T
Joy e[rur Jed 4so0g OZ6L 6I6I

SJUNWIIARG 9731907 9S1N07=0M

“UOTILING} UT POjsT] JOU SoyeIS UT poplVeMe OdAY SITY] JO YIOM ON 1

Gel % O80 “6FL |
28% O08 “OF | eae mA
CNG 992 1E) we | So aS SPXO],
CL '% BOG: Chile -1)| spa ae TINOSSTy
(Ge OR waar, GR le eames on
PLS 7G0:-0Gic blll eens sesuey
COL °% OSL 102 ee ae ae od
1S ‘2$ TO OL | ee ee Bploly
“sph “by
“pared
Saabs aim: 10
qed ood patel aie
OSRIOAV ae TEL 91819

‘ponuljuop-—-SINAWAAVE ALAYONOO GIV-IVUACAIA JO LSOO “a

67

181 6&

G88 162
6PL 9E
EIP 08
L9G "Gh

Z8E ‘LE

£99 “FF
G80 ‘eh
989 “ES

APPENDIX.

0261

FFz ‘OF

66S ‘0 __

G6T ‘86
960 “0€

1¥6 ‘08

9T0 ‘88
G88 “6G

009 ‘68
LSE ‘66
GOL “ES
T19 ‘9%

ee ee

O16 ‘28
BET ‘26
SFG ‘LES

6161

*soolid eseyy

190)

pese’gq—A uo

quoTOACd 400J-8T
oJ oTtut Jod 4sop

1
|

szOneInAe UI poysT] Jou Beoiels 4 ul peREae adel 814} JO YIOM ON

*STOTIOOS TLV “SONTUL [TV
““SSOUyory, WLOjTUN ,,2 | O9'E $6::1
ON marae Go Setar
“--sospo ,,9 “10]W99 Fi, alee ayes 3:1
“*"-sedpe ,,1 ‘19}U99 6 | Go‘ $:3:1
"“"*se8po ,,9 “10}U09 {8 | ZS 28:1
“-=-sospo ,,¢ ‘107190 ,,2 | SZ°% €:0:1
“---sospe ,,9 ‘109U0D ,,8 | Go's €:6:1
““ssouryortyy Ursojun ,,L | 06% COZaT
**ssouxoryy Ta10j;TUN ,,9 0S °S €:3:1
*---sospe ,,9 ‘10]U80 ,,8 | 09°E Cea
“-ssouyory} TaI10jTUN ,,8 | OS °% $E:0:T
"177 se8pe 2 “4070109 7,8 88 'T Hescol
“"ssouyoryy Ursojtan ,,¢ | Lp V::1
““ssouspory} UlojTun ,,h | Lys B:6o:1
“SpUunOgT
“paved
eienbs
*MOT}NOS-SSOI ree “XT,
-OD.10J
U0 YY

0661

€9L°€

€8°G
8h €
88°C
€0°F
PGE
G6 'P

08%
06°C
92 °E
66°
GGG
96 “S$

“que UL
-O LOJUIOL
SurIpnypout
‘pied
aienbs
Jod 9oT1d
OsBIOAY

000 “289 “E

G68 ‘CT
116 ‘61
O&P (9G
GCP “F9

S16 ‘82

L10 ‘LT ;
BEI “CEP ‘T
S¥8 ‘09

BLT (06
066 84
18 "6
16% ‘998 ‘T
BFS ‘6
ZG9 “CTE
“sph “by

“F0nq
10 popileMme
vole [VIO T,

~“ssouyporyy) ULLOjTUN ,,)
“--sespo ,,9 ‘109t0) 21
“"=-sespo ,,9
---sospo ,,9 ‘109000 ,,£2

“---sedpoe ,,¢ ‘10999 |)
“---sodpo ,,9 610909 ,,8

~~ -sedpo ,,8 ‘10}U109 , 01
"---sadpo ,,9 ‘10700 18
% “S03 po WL “104 U99 Gs
“=--sespo ,,¢ ‘109m00 uh

“-""sospo ,,2 ‘109u00 8
3 een) uaoj1un. ,,G

ssoUpoy} UTLOJTUN , ,f

"MLO1}00S-SSO.1,)

PSPUSMOAR 9}OIDUOD podlojuIoY

‘penutjwop—S, LNANAAVd ALAYONOO AIV-IVYAGAA FO LSOO ‘d

6161

a ee ee

SOOM SOXTUL TTY | $98 °% TLS ‘FEL “8
09° $E:0:1 G6 T CFS 6 727° °"*°UTSTOOSTAA
Son ip, Bo eee egg la gsiemens ARES ed [ca art eee | Ee soreecis""BTUTSITA ISOM
86% £:6:T 19° 619 ‘88 “=> =" OAS UTS MA,
‘TJD 8 | GOS | FETT 68% C09 ‘08 chee age 0d
G61 {i cara tess y eee: we!) G00 era ames sea Oa
0L°% (eet! 09°€ POPS | sBxOL,
GZ S:0:0 &8'°S 169 TeL‘% |" BruRAyAsuUEg
lee STS epee aang setae a tage eaeage eee LOO (0)
09% 2T0:T C26 e551 Olen indent omcl
09° Sebel! SUa 156 ‘E91 ee eon
G9"L S:4L:T 02 '€ oge ‘TI “*-eBUT[OIeD YON
96 T S:41: 1 oo °% GbE “CST "757" " "HIO X AON
otitis nas epee are ee See TSS |e eon tae eens enero CLOT UOIAT
ip oa iee We | Pc hone ect cel fae es | OES OO IO COSA AMUTEC INS |
eacienbesoeiaes neste et eecen|ecee eee eee [eee ereeceeee[eeee ere es = QC
881 $8:3:T 69''E PSI ‘6L Soe a EO
Lbs yeaa 1g °% 6F6 ‘606 Fen sae en OGh
Lvs P:GuL 89'7$ | Sh8 LP ** * BIULIOJTTD)
“Spunod “sph “by
‘ “70 UL
9 pay -90.10] UIOI
Rodi suypnpouy| — “Hm
: “XT ‘paek | 10 popreme
peuE o1enbs | Bore [BIOT,
eotey aod oot "99819
“Upa osvsoAy

ADDITIONAL COPIES
OF THIS PUBLICATION MAY BE PROCURED FROM
THE SUPERINTENDENT OF DOCUMENTS
GOVERNMENT PRINTING OFFICE
WASHINGTON, D. C.
AT

15 CENTS PER COPY
V