STANDARD SPECIFICATIONS
FOR PUBLIC WORKS CONSTRUCTION
Architectual
LESTON
B-SUBGRADES AND FOUNDATIONS
FOR PAVEMENTS
B1-Earth Subgrade
B2-Pavement Foundation of New Macadam
B3-Pavement Foundation of Reconstructed Macadam
B4-Pavement Foundation of Portland Cement Concrete
B5-Pavement Foundation of Asphaltic Concrete
B6-Pavement Foundation of Tar Macadam
(Hot Penetration Type)
B7-Pavement Foundation of Tar Macadam
(Cold Penetration Type)
and other th
B8-Pavement Foundation of Reconstructed Brick, Block
or Concrete Pavement
B9-Pavement Foundation of Asphalt Macadam
(Penetration Type)
AMERICAN PUBLIC WORKS ASSOCIATION
CHICAGO, ILLINOIS
UNIVERSITY OF MICHIGAN LI
4
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
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Specification for
EARTH SUBGRADE
A.P.W.A.-B1-36
ARCHITECTURAL
LIBRARY
1. General. The grading and preparation of earth subgrades
for pavement foundations or bases of all types shall conform to
the requirements of these specifications.
2. Stakes. The extent of the necessary grading is shown ap-
proximately upon the plans which form a part of this contract.
The engineer will from time to time set stakes which, taken in
connection with the cross-section shown upon the plans, will
indicate the exact amount of cut or fill.
3. Resetting Stakes at Contractor's Expense. After stakes.
have been set, it shall be the duty of the contractor and his em-
ployees to protect them. Stakes which become moved or dis-
turbed will be reset by the engineer at the contractor's expense,
and the cost of such replacement shall be paid by the contractor
into the public treasury before payment under this contract is
made.
4. Excavated Material Used for Fill on Job. Material removed
in excavation shall be used in fills on the same job, if, in the opinion
of the engineer, it is suitable for this work.
5. Disposal of Surplus Material on Public Property. If ex-
cavation is in excess of filling, the excess material shall be hauled
and spread on streets, alleys, highways or other public property
if so indicated on the plans, or if ordered to do so by the engineer,
on public places, as above, within fifteen hundred (1500) feet of
the work. Provided that such filling in the public places shall
not be carried above the proposed or established grades, and that
it shall be spread in such a manner as to leave the streets, alleys
or public highways in a condition satisfactory to the engineer;
provided, further, that the city does not guarantee to provide
dumping spaces for all surplus earth under this contract.
6. Disposal of Surplus Material on Private Property. Material
removed in excavation in excess of the amount required for filling
on this contract, or filling on other streets, alleys, highways, and
public property as shown on the plans or as ordered by the
engineer, may then be deposited on any private property within
the benefit or taxing district of this contract should any owner of
said property so request and make arrangement for filling on his
property with the contractor; provided, further, that said ar-
rangements shall consist of only a reasonable charge to cover the
cost of moving excess material from source on job to property to
be filled.
K
B1
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
7. Material Unsuitable for Filling and That in Excess. Ma- B1
terial removed in excavation and not suitable for filling or in
excess of the amount required for the filling on this contract
or for filling on other streets, alleys, highways, and public places
as indicated on the plans, or as ordered by the engineer, or for
filling in private property in the taxing district, shall become
the property of the contractor and shall be disposed of at such
places as he may secure. The cost of such disposal shall be in-
cluded in the price bid for "Grading." If the material is disposed
of on private property he must secure the written consent of the
owner.
G
8. Excavation Below the Subgrade. Where the work is in
cut, the contractor will in general be expected to remove the ex-
cavation down to the true surface of the subgrade. Should he cut
below the true surface of the subgrade as much as four (4)
inches, he will be permitted to refill up to the subgrade with ma-
terial satisfactory to the engineer, and this material will be com-
pacted in connection with the final rolling of the subgrade.
Should the contractor cut more than four (4) inches below the
true surface of the subgrade, he shall refill up to the subgrade
with macadam. In connection with the work of refilling, no pay-
ment will be made for the refilling with earth for four (4) inches
below the true surface of the subgrade or for refilling the whole
cut with macadam if more than four (4) inches below the true
surface of the subgrade.
9. Borrowed Material. If filling is in excess of excavation, the
contractor shall secure the necessary material from such borrow
pits as may be indicated on the plans accompanying this contract,
or if no such location is indicated or if the amount in the indicated
location is insufficient he shall furnish material satisfactory to the
engineer. If material is obtained from public streets or alleys, it
shall be removed in such manner as to leave the streets or alleys in
a condition satisfactory to the engineer.
10. Removal of Sod. No fills shall be made on sod without first
breaking this sod to a depth of at least six (6) inches by means of
a plow or by other means satisfactory to the engineer.
11. Filling in 12-Inch Layers. All fills exceeding twelve (12)
inches in depth to the proposed subgrade, shall be made in layers
not more than twelve (12) inches thick, and shall be thoroughly
compacted by means of a self-propelled roller weighing not less
than six (6) tons. Inaccessible places and those places where
rolling is not practical on account of possible damage to sub-
surface structures, shall be compacted with hand rammers weigh-
ing not less than one-half (½) pound per square inch of face of
rammer. Payment for compacting of layers in fills by rolling or
by ramming will be included in the price bid per cubic yard for
"Grading."
12. Removal of Unfit Material. All organic or other perishable
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
and spongy material will be excluded from fills, and when B1
directed by the engineer must be removed to a depth of at least
eighteen (18) inches below the finished surface of the subgrade.
When the contractor is directed to remove unfit material from
the subgrade, he will be paid for removing it at the price bid for
"Grading" and shall bring the surface to correct elevation as
directed by the engineer by means of earth, concrete, or macadam
which will be paid for at the prices bid for grading or materials
used.
13. Removing and Grubbing of Stumps. Trees that rise less
than two (2) feet above the ground and the trunks of which, as
nearly as may be determined, would have measured three (3)
inches or more at the point two (2) feet above the ground, shall
be construed to be stumps. When it is found necessary to re-
move stumps thus defined, time shall be kept on the labor in-
volved, and paid for as an extra.
14. Solid Rock. Should solid rock (boulders of one (1) cubic
yard or more in content, or ledges in their original bed) be en-
countered, it shall be removed to grade and shall be estimated
and paid for by the cubic yard at a price of three (3) times the
price bid, per cubic yard, for "Grading."
15. Sidewalk Grading. Sidewalk grading included in this con-
tract shall be done at the same time the roadway is rough graded.
16. Protection of Inlets and Manholes. Due care must be
taken not to disturb inlet covers, manhole heads, valve boxes,
public utility boxes, sprinkling plugs or fire plugs, house con-
nections or private water pipes. If not set to proper grade, they
will be adjusted by the various public departments or public util-
ity corporations or property owners, unless otherwise directed by
the engineer. The contractor will be held responsible for any
damage done to inlet covers, manhole heads, boxes, and plugs;
also for any damage done to house connections or private water
pipes and accessories if two (2) feet or more below top of curb or
one (1) foot or more back of face line of curb, in the case of street
construction, or if two (2) feet or more below the grade of the
finished pavement in connection with alley construction.
Challen
17. Drainage. Wherever water collects on the work under
construction or adjacent to it on account of broken water pipe,
the washing of streets or alleys, or rain or other causes, such
water must be drained at the earliest possible moment to a man-
hole, inlet, or natural drain, and if no such place be available, the
water shall be pumped or bailed out in order to advance the dry-
ing out of the subgrade and to prevent damage to building or
other foundations and the seeping of water into cellars or base-
ments of adjacent buildings.
18. Payment for Grading. The price bid shall include the
whole cost of excavating or filling as above specified, of grubbing
of stumps necessary in carrying out the work, except as other-
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
wise herein specified, of excavating and removing all materials of B1
every description that may be encountered, unless otherwise
herein specifically provided for, of shaping the subgrade to exact
lines and grades given, of sloping cuts and street, alley, and side-
walk intersections and approaches, and of rolling or tamping be-
low the subgrade in the case of fills; and in connection with street
construction, the sloping and filling between the curb and side-
walk pavement, and the grading and shaping of sidewalk spaces
where shown on plans. The work will be estimated to the grades
and slopes shown on the plans unless other lines shall have been
given by the engineer.
19. Rolling the Subgrade. Before the subgrade will be con-
sidered ready for foundation, it must have been compacted with
a self-propelled roller weighing not less than six (6) tons. On in-
accessible places where rolling cannot be carried out, the sub-
grade shall be compacted by tamping to the satisfaction of the
engineer. If after the subgrade has been rolled to the satisfaction
of the engineer and has been accepted by him, it is disturbed by
hauling over it or in some other manner, it shall be restored to its
condition at the time of acceptance by rolling and reshaping or by
filling the ruts with macadam without any additional compensa-
tion.
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20. Payment for Rolling. Payment for compacting the surface
of the subgrade by rolling, or tamping in inaccessible places,
as directed by the engineer, will be made at the price bid per one
hundred (100) square yards for "Rolling the Subgrade.
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21. Crossings and Driveways. Where indicated on the plans
or ordered by the engineer, the contractor shall provide tem-
porary crossings, driveways or walks of the character designated
over the subgrade, foundation, or finished pavement. Where
macadam, gravel, sand, limestone screenings, or cinders are
ordered and used, they will be paid for to the amount ordered
and placed at the prices bid, which prices shall include the placing
and removing of the material. Where lumber is ordered and
placed, it shall be paid for at the price bid for "two (2) inch
plank," per one thousand (1000) feet, board measure, which price
shall include the furnishing of the plank, laying same, spiking or
wiring to the necessary longitudinal plank, maintaining and re-
moving. Material once used and removed shall be the property
of the contractor and may again be used and paid for if in satis-
factory condition.
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF NEW MACADAM
A.P.W.A.-B2-36
I. GENERAL
The macadam foundation shall consist of mineral aggregate
laid in courses each composed of coarse aggregate and filler and
having a compacted thickness of not less than three (3) inches.
nor more than four (4) inches. The whole shall form a founda-
tion having a compacted thickness of not less than six (6) inches
and shall conform to the grades and cross-sections shown on the
plans.
II. MATERIALS
I. Coarse Aggregate. The coarse aggregate shall consist
of broken stone, mine tailings, or slag, of reasonably uniform
quality throughout and free from an excess of flat or elongated
pieces. Broken stone or mine tailings shall have a percentage of
wear of not more than eight (8). Slag shall weigh not less than
65 pounds per cubic foot. Ninety-five per cent shall pass a three
and one-half (3½) inch screen and not more than 15% shall pass
a two and one-half (2%) inch screen.
2. Filler. The filler shall consist of stone screenings or sand,
95% of which shall pass a three-quarter (34) inch screen and 40%
to 80% shall pass a one-quarter (4) inch screen.
3. Methods of Testing. Methods of testing shall be as follows:
(a) Per cent of wear, Standard Test D2-33, American Society
for Testing Materials.
(b) Weight per cubic foot of broken slag, Standard Method
C29-27, American Society for Testing Materials.
(c) Screen tests, Standard Method D18-16, American Society
for Testing Materials.
III. CONSTRUCTION
1. Spreading Coarse Aggregate for First Course. The coarse
aggregate shall be spread upon the prepared subgrade or subbase
course in a uniformly loose layer of correct depth, from piles or
by means of approved spreading devices, in such manner that
uniform compaction may be secured. In no case shall the mate-
rial be dumped directly in place and suitable precautions shall be
taken to prevent rutting of the subgrade during spreading. The
coarse aggregate shall not be spread upon a wet subgrade nor
B2
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
more than an average day's work in advance of rolling and filling. B2
2. Compacting and Filling Coarse Aggregate. (a) The coarse
aggregate shall be rolled with a three-wheel power-driven roller
weighing not less than ten (10) tons, until it has been thoroughly
compacted to a firm, even surface. Rolling shall start longitu-
dinally at the sides and gradually proceed toward the center of
the roadway, overlapping on successive trips by at least one-half
the width of the roller and shall continue until the aggregate does
not creep or wave under the weight of the roller.
(b) Filler shall then be spread with shovels from piles along the
side of the roadway. It shall be placed in thin layers and worked
into the voids by brooming and rolling, without the use of water,
until no more can be forced into the road. The surface shall then
be sprinkled with water and rolled as previously described. Dur-
ing rolling additional filler shall be spread in thin layers where
bare spots appear and shall be broomed off spots where an excess
has been applied. Filler shall be used only in such quantity as
required to fill the voids and leave least possible surplus on the
surface after sprinkling and rolling are completed.
3. Second Course. The second course of coarse aggregate and
filler shall be constructed upon the compacted first course exactly
as described in Section III, 1 and 2.
4. Admission of Traffic. In order to complete the consolidation
of the base and to remove surplus filler from the surface when di-
rected by the engineer, traffic shall be permitted upon the prepared
base course for a period after it has thoroughly dried out. During
this period the surface shall be maintained by the addition of new
filler where there are indications of raveling, or by brooming
back toward the center of the road any filler which may have been
removed by traffic and may have accumulated along the sides.
5. Condition Prior to Laying Wearing Course. (a) If at any
time, prior to laying the wearing course or pavement proper, the
subgrade material becomes churned up or mixed with the base
course materials, such mixture shall be dug up and removed. At
such places the subgrade shall then be reshaped and compacted
and the base relaid, filled with clean aggregate, and compacted.
If any irregularities develop in the surface of the base they shall
be remedied by loosening the surface and removing or adding
coarse aggregate as may be required, after which the entire area
including the surrounding surface shall be rolled with the addi-
tion of filler and water until it is compacted satisfactorily to a
uniform surface, such that it will not vary more than one-half (½)
inch from a twelve (12) foot straight edge.
(b) Immediately before the laying of the wearing course the
base course shall be cleaned of all loose or caked filler, dirt, or other
foreign material, so as to present a uniformly rough or granular
appearance, admitting of complete bond with the wearing course.
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF RECONSTRUCTED MACADAM
I. GENERAL
com-
The base course shall consist of an existing stone or slag
road to which, after scarifying, there shall be added a mineral
aggregate composed of coarse
coarse aggregate and filler
pacted so as to form a base course having a total thickness of not
less than six (6) inches, and conforming to the grades and cross-
sections shown on the plans.
II. MATERIALS
1. Coarse Aggregate. The coarse aggregate shall consist
of broken stone, mine tailings, or slag. It shall be of reasonably
uniform quality throughout and free from an excess of flat or
elongated pieces. Broken stone or mine tailings from which it is
produced shall have a per cent of wear of not more than 8. Slag
from which it is produced for each size specified shall weigh not
less than sixty-five (65) pounds per cubic foot.
2. Filler. The filler shall consist of stone screenings.
Size
A.P.W.A.-B3-36
3. Gradation. When tested by means of laboratory screens the
coarse aggregate and screenings shall meet respectively the fol-
lowing requirements and be uniformly graded between the limits.
given:
Coarse Aggregate
2½-3½".
0 - 3/4"
Screenings
0 - 1½"..
½”………….
Per Cent Passing Screen
3/4″
1/2"
312"
22"
.95-100 0-15
95-100
1/4"
40-80
95-100
40-80
4. Methods of Testing. Methods of testing shall be as follows:
(a) Per cent of wear, Standard Test D2-33, American Society
for Testing Materials.
(b) Weight per cubic foot of broken slag, Standard Method
C29-27, American Society for Testing Materials.
(c) Screen tests, Standard Method D18-16, American Society
for Testing Materials.
III. CONSTRUCTION
1. Preparation of Existing Road. The existing road surface
B3
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
shall be lightly scarified by machine or hand picking uniformly B3
over its entire width in order to afford a proper bond for the
new aggregate, extreme care being taken in case of telford founda-
tion not to disturb the foundation stones. The old foundation
shall be thoroughly examined and all areas found unsuitable
for foundation for the new pavement shall be removed, and after
thoroughly consolidating the sub-base, be replaced with suitable
material of the same kind as the old pavement or filled with Port-
land cement concrete, asphaltic macadam, or asphalt concrete.
After scarifying, the dust, screenings, and dirt shall be separated
from the coarser stone by forking or other suitable means, and all
fine material and dirt removed, sufficient material being removed
to provide for reconstruction to uniform grade and make possible
the rebuilding of the crown to a satisfactory contour. The re-
maining coarse material shall then be brought to a grade parallel
to the proposed surface of the new pavement by filling depressions
and removing high spots and thoroughly compacting by rolling
before the addition of any new material. Suitable material from
the old pavement may, upon approval of the engineer, be used
in the preparation of the foundation. If sufficient suitable
material is not obtained from the old pavement, new crushed stone
or slag must be supplied to complete the construction of the new
foundation to the required depth below the surface of the new
pavement. The new foundation shall contain sufficient fine ma-
terial to give it a suitable rigidity. If the road is to be widened,
trenches of correct width and not less than four (4) inches below
the old road surface shall be cut along the sides of the road and
filled with coarse aggregate which shall be thoroughly tamped or
rolled so as to conform with the reshaped surface. In case the old
pavement is of telford macadam and the top stone is removed
down to the foundation stones, the irregularities in the new foun-
dation shall be built up to the required grade and contour by laying
of asphaltic macadam or asphaltic concrete foundation of the re-
quired thickness.
Ch
2. Spreading Coarse Aggregate. The new coarse aggregate
shall be spread on the prepared road surface in a uniformly loose
layer not more than four (4) inches in depth from piles or by
means of approved spreading wagons, in such manner that uni-
form compaction may be secured. In no case shall the material
be dumped directly in place. The coarse aggregate shall not be
spread more than an average day's work in advance of rolling and
filling.
3. Compacting and Filling Coarse Aggregate. (a) The coarse
aggregate shall be rolled with a three-wheel power-driven roller
weighing not less than ten (10) tons, until it has been thoroughly
compacted to a firm, even surface. Rolling shall start longi-
tudinally at the sides and gradually proceed toward the center
of the roadway, overlapping on successive trips by at least one-
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
half the width of the roller and shall continue until the aggregate B3
does not creep or wave under the weight of the roller.
(b) Screenings shall then be spread with shovels from piles
along the side of the roadway. They shall be placed in thin layers
and worked into the voids by brooming and rolling, without the
use of water, until no more can be forced into the road. The
surface shall then be sprinkled with water and rolled as previously
described. During rolling additional screenings shall be spread
in thin layers where bare spots appear and shall be broomed off
spots where an excess has been applied. Screenings shall be used
only in such quantity as required to fill the voids and leave the
least possible surplus on the surface after sprinkling and rolling
are completed.
4. Admission of Traffic. In order to complete the consolidation
of the base and to remove surplus screenings from the surface,
when directed by the engineer, traffic shall be permitted upon the
prepared base course for a period after it has thoroughly dried
out. During this period the surface shall be maintained by the
addition of the new screenings where there are indications of
raveling, or by brooming back toward the center of the road
any screenings which may have been removed by traffic and
accumulated along the sides.
5. Condition Prior to Laying Wearing Course. (a) If at any
time, prior to laying the wearing course or pavement proper, the
subgrade materials become churned up or mixed with the base
course materials, such mixture shall be dug up and removed. At
such places the subgrade shall then be reshaped and compacted
and the base relaid, filled with clean aggregate, and compacted.
If any irregularities develop in the surface of the base they shall
be remedied by loosening the surface and removing or adding
coarse aggregate as may be required, after which the entire area
including the surrounding surface shall be rolled with the addition
of screenings and water until it is compacted satisfactorily to a
uniform surface.
(b) Immediately before the laying of the wearing course, the
base course shall be cleaned of all loose or caked screenings, dirt,
or other foreign material, so as to present a uniformly rough or
granular appearance, admitting of complete bond with the wear-
ing course.
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF PORTLAND CEMENT CONCRETE
A.P.W.A.-B4-36
I. GENERAL
Upon the properly prepared subgrade shall be spread a layer of
Portland cement concrete which, when thoroughly rammed, shall
have the thickness specified and conform to line and grade and
typical cross-section.
II. MATERIALS
1. Portland Cement. (a) Cement for all concrete shall comply
with "Specifications and Test for Portland Cement" (C9-30,
A. S. T. M.).
(b) Cement, if stored, shall be placed under a suitable water-
tight covering, upon a floor properly raised from the ground.
(c) Contractor shall be permitted to use only cement which has
passed the preliminary and 7-day tests of an approved testing
laboratory. Should cement fail to pass the 28-day test no addi-
tional cement from that particular mill will be permitted used in
the work until tests show that the product of that plant has
met standard requirements.
(d) Cement which has deteriorated in any way during storage
may be rejected.
2. Fine Aggregate.¹ (a) Fine aggregate shall consist of sand
or other approved inert materials with similar characteristics, or
a combination thereof, having hard, strong, durable particles and
shall conform to the requirements of these specifications.
(b) The maximum percentages of deleterious substances shall
not exceed the following values:
Removed by decantation.
Shale
Coal
Clay lumps
Other local deleterious substances (such as alkali,
mica, coated grains, soft and flaky particles)..
•
•
Per cent
By Weight
3
1
1
1
It is recognized that under certain conditions maximum per-
centages of deleterious substances less than shown in the table
should be specified.
1
The specifications for fine and coarse aggregates conform to the
A. S. T. M. Tentative Standard for Concrete Aggregates (C33-36T).
B4
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(c) The sum of the percentages of shale, coal, clay lumps, sott B4
fragments, and other deleterious substances shall not exceed 5%
by weight.
(d) All fine aggregate shall be free from injurious amounts of
organic impurities. Aggregates subjected to the colorimetric test
for organic impurities and producing a color darker than the
standard shall be rejected unless they pass the mortar strength
test as specified in (f).
(e) Fine aggregate shall be well graded from coarse to fine and
when tested by means of laboratory sieves shall conform to the
following requirements:
Passing
3/8-in. sieve
No. 4 sieve
No. 16 sieve
No. 50 sieve
No. 100 sieve
These percentages are suggested as limiting percentages but
they may be altered within these limits to suit local conditions.
Per cent
100
85 to 100
45 to 80
2 to 30
0 to 5
(f) Fine aggregates, when subjected to the mortar strength
test, shall have a tensile or compressive strength of not less than
100% of that developed by mortar of the same proportions and.
consistency made of the same cement and standard Ottawa sand.
3. Coarse Aggregate.¹ Coarse aggregate shall consist of
crushed stone, gravel, blast-furnace slag, or other approved inert
materials of similar characteristics, or combinations thereof,
having hard, strong, durable pieces, free from adherent coatings
and conforming to the requirements of these specifications.
(a) The maximum percentages of deleterious substances shall
not exceed the following values:
Removed by decantation
Shale
Coal
Clay lumps
Soft fragments
•
Other local deleterious substances (such as alkali,
friable, thin, elongated, or laminated pieces)
•
Per cent
By Weight
1
1
1
1/2/3
It is recognized that under certain conditions maximum per-
centages of deleterious substances less than those shown in the
table should be specified.
(b) The sum of the percentages of shale, coal, clay lumps, and
soft fragments shall not exceed 5% by weight.
(c) Coarse aggregate shall be well graded, between the limits
1
The specifications for fine and coarse aggregates conform to the
A. S. T. M. Tentative Standard for Concrete Aggregates (C33-36T).
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
specified, and shall conform to the following requirements:
Passing in. Sieve
Passing in. Sieve
(maximum size)
(intermediate)
(½ maximum size)
Passing in. Sieve
(intermediate) ...
(as needed)
Passing No. 4 Sieve or a 14-in. Screen..
25
Base concrete
Surface concrete
•
•
•
Per Cent by Weight
..not less than 95
.not less than 40
..not
less than 75
•
..not less than
.not more than
.not more than 10
Where a range is shown the engineer should use an appropriate.
figure within the limits recommended. The percentages given are
recommended, but may need to be altered to suit local conditions.
..
(d) In case the concrete resulting from a mixture of aggregates
approaching the extreme limits for gradation is not of a workable.
character, or when finished does not exhibit a proper surface, due
to an excess of particles approximately 8 to ½ in. in size, either
a fine aggregate having a sufficiently greater percentage of fine
material, or a coarse aggregate having a sufficiently smaller per-
centage of fine material shall be used.
(e) Blast-furnace slag that meets the grading requirements of
these specifications shall conform to the following minimum
weight requirements:
• •
...65 lb. per cu. ft.
..70 lb. per cu. ft.
(f) Coarse aggregate shall pass a sodium sulphate accelerated
soundness test, except that aggregate failing in the accelerated
soundness test may be used if it passes a satisfactory freezing
and thawing test.
4. Methods of Sampling and Testing: The properties enu-
merated in these specifications shall be determined in accordance
with the following methods of test of the American Society for
Testing Materials, except as specified in (e).
(a) Sampling: Standard Methods of Sampling Stone, Slag,
Gravel, Sand and Stone Block for Use as Highway Materials, In-
cluding Some Material Survey Methods (D 75-22).
(b) Sieve Analysis: Standard Method of Test for Sieve
Analysis of Aggregates for Concrete (C 41-36).
(c) Decantation Test: Standard Method of Decantation Test
for Sand and Other Fine Aggregates (D 136-28).
(d) Organic Impurities: Standard Method of Test for Organic
Impurities in Sands for Concrete (C 40-33).
(e) Mortar Strength: Methods of Making Compression and
Tension Tests of Fine Aggregate for Concrete as adopted by the
American Association of State Highway Officials.
(f) Compressive Strength: Standard Methods of Making
Compression Tests of Concrete (C 39-33).
B4
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(g) Soundness: Tentative Method of Test for Soundness of B4
Coarse Aggregate (Sodium Sulphate Soundness Test). (C 89-
35T.)
(h) Freezing and Thawing: Proposed Method of Test for
Freezing and Thawing of Concrete and Concrete Aggregates
(Proc., Vol. 32, I, 364).
(i) Shale and Coal: Proposed Method of Test for Percentage
of Shale in Aggregate (Proc., Vol. 28, I, 362).
(j) Soft Fragments: Proposed Method of Test for Quantity
of Soft Pebbles in Gravel (Proc., Vol. 28, I, 363).
(k) Coal and Lignite: Tentative Method of Test for Determi-
nation of Coal and Lignite in Sand (C 123-36T).
(1) Moisture: Standard Method of Test for Field Determina-
tion of Surface Moisture in Fine Aggregate (C 70-30).
(m) Consistency: Tentative Method of Test for Consistency
of Portland Cement Concrete (D 138-32T).
(n) Weight of Slag: Standard Method of Test for Unit Weight
of Aggregate for Concrete (C 29-27).
5. Storage of Aggregates: Sites of storage piles shall be
cleaned of all debris and organic matter. Piles of both fine and
coarse aggregate shall be so stored as to avoid the inclusion of
foreign materials. Fine aggregate and coarse aggregate shall be
stored separately. Division bulkheads shall be used if necessary
to prevent adjacent piles overlapping. Piles of both fine and
coarse aggregate shall be built in layers not over three feet thick
to prevent segregation. Building piles in the shape of a cone by
dropping materials in the center of the pile is prohibited.
6. Water: Water used for mixing concrete shall be free from
any organic or mineral matter that, in the opinion of the engineer,
is injurious to concrete.
III. CONSTRUCTION
1. Proportioning. (a) Concrete shall be proportioned for the
water-cement ratio of not more than 7½ U. S. gallons of water per
94 pound sack of cement, including the water in the aggregate, and
for a proper workability.
(b) The approximate volume of Portland cement to the sum of
the volumes of fine and coarse aggregates measured separately in
a dry state shall be not less than one to nine.
2. Workability. (a) The workability will be considered proper
when the mass can be puddled readily into the corners and angles
of the forms and around the reinforcement without excessive
spading, and finished without the accumulation of water or
laitance on the surface.
(b) In no case shall the amount of coarse aggregate be such as
to cause harshness or honeycombing in the structure.
(c) When the forms are removed concrete faces shall show
smooth and sound. The concrete, when placed, shall show a
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
slump of from three (3) inches to four (4) inches when tested in B4
accordance with "Tentative Method of Test for Consistency of
Portland Cement Concrete," D138-32T, American Society for
Testing Materials.
3. Limiting Proportions of Fine and Coarse Aggregate. The
ratio of fine to coarse aggregate shall not be less than one to two,
nor more than one to one.
4. Control of the Proportions. (a) The quantity of mixing
water specified for each sack of cement is the maximum permis-
sible. The normal operation of the concrete shall be such that
with the batch to batch variation in water content, this quantity
shall not be exceeded. Free water or moisture carried by the ag-
gregate must be included when computing the total quantity of
water per batch. When dry aggregates are used, the quantity of
water may be increased by an amount equal to that absorbed by
the aggregate in a period of thirty (30) minutes.
(b) The method of measuring all the materials shall be such
that the quantity of each ingredient in the mix can be closely con-
trolled during the progress of work, and can be easily checked at
any time by the engineer.
5. Measurement of Moisture in Aggregates. Moisture in the
aggregates shall be measured by a method satisfactory to the
engineer. The results of all moisture determinations shall be open
to inspection of the engineer or his representative. The measure-
ments shall be made regularly during the day at such intervals as
directed by the engineer. The contractor shall permit the use of
his apparatus by the engineer for making independent determina-
tion as desired.
6. Uniformity of Aggregates. To avoid unnecessary or hap-
hazard changes in consistency, the aggregates shall be obtained
from a source which will insure uniform quality and grading dur-
ing any single day's operation, and they shall be delivered to the
"work and handled in such manner that variations in moisture
content will be not interfere with the steady production of con-
crete of a reasonable degree of uniformity.
7. Test of Concrete. Frequent tests shall be made throughout
the work, as directed by the engineer, to determine whether the
strength and quality is being realized in the concrete produced
under the specifications. The contractor shall furnish samples of
concrete and other materials for test specimens, and shall co-
operate in every way to the end that concrete of the desired quality
shall be produced.
8. Mixing. (a) The mixing of concrete, unless otherwise au-
thorized by the engineer, shall be done in a batch mixer of ap-
proved type. The mixing shall be done so as to insure a uniform
distribution of the materials throughout the mass. The mixture
shall be uniform in color, and homogeneous.
5
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(b) Cement shall be delivered to the mixer in bags, and bags B4
shall not be opened until aggregates are ready to be placed in
mixer.
(c) The mixer shall be equipped with suitable charging hopper,
water storage, and a water-measuring device, controlled from a
case which can be kept locked, and so constructed that the water
can be discharged only while the mixer is being charged. It shall
also be equipped with an attachment for automatically locking the
discharge lever until the batch has been mixed the required time
after all materials are in the mixer.
(d) All water valves must be kept tight to prevent leakage.
(e) The entire contents of the drum shall be discharged before
recharging.
(f) The mixer shall be cleaned at frequent intervals while in
use.
(g) The volume of the mixed material per batch shall not ex-
ceed the manufacturer's rated capacity of the mixer.
9. Time of Mixing. The mixing of each batch shall continue
not less than one minute after all the material is in the mixer,
during which time the mixer drum shall rotate from fourteen to
twenty revolutions per minute.
10. Hand Mixing. (a) When hand mixing is authorized by the
engineer, it shall be done on a water-tight platform. The cement
and fine aggregate shall be mixed dry until the whole is of uni-
form color. The water and coarse aggregate shall then be added
and the entire mass turned at least three times, or until a homo-
geneous mixture of the required consistency is obtained.
(b) No retempering of concrete shall be allowed under any con-
sideration, and the re-mixing of concrete with additional cement,
aggregates, or water, shall not be done, except by methods ap-
proved by the engineer.
11. Forms. (a) Setting: Forms shall be well staked so that
they will hold firmly to established line and grade. The inside of
forms shall be coated with mineral oil or thoroughly wetted before
depositing concrete. Special precautions shall be taken to prevent
leakage of mortar through or under side forms.
(b) Removal: Forms shall not be disturbed until the concrete
is adequately hardened.
12. Depositing Concrete. (a) Before depositing a run of con-
crete, hardened concrete and foreign material shall be removed
from the inner surface of the mixing and conveying equipment.
(b) Before depositing concrete, débris shall be removed from
the space to be occupied by the concrete, and the prepared sub-
grade thoroughly wetted.
13. Handling. (a) Concrete shall be handled from the mixer
to place of final deposit as rapidly as practicable and in a manner
that will prevent segregation of the ingredients. It shall be de-
posited in the forms and on the completed subgrade so as to main-
6
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
tain a plastic surface conforming to standard section until the B4
completion of the unit.
(b) In no case shall concrete that has partly hardened be de-
posited in the work, nor shall water be added to concrete after it
leaves the mixer.
14. Central Mixing Plants. Concrete prepared in a central mix-
ing plant may be used, provided the aggregate has not segregated
during transit. Concrete must not be hauled for a time greater
than that required for securing initial set. If water is added after
the concrete leaves the mixer, only enough shall be added that the
total specified water shall not be exceeded, and it must be
thoroughly mixed by a mechanical mixer before being placed.
15. Compacting and Finishing. (a) Concrete, during and im-
mediately after depositing, shall be puddled thoroughly and
tamped solidly on subgrade so as to eliminate voids or honeycomb
pockets, and shall be thoroughly worked around imbedded fix-
tures.
(b) The surface of concrete base shall be finished in such
manner as required by the paving surface to be applied, and shall
conform to line and grade and crown of roadway. When construc-
tion joints are necessary, same shall be placed vertically in a
straight line, or as indicated by the engineer.
16. Protection and Curing. (a) Concrete base shall be pro-
tected from workmen, or others, walking thereon before final set,
and shall be kept wet continually for three (3)¹ days, unless a
shorter time be allowed by the engineer. Sprinkling shall com-
mence as soon as the concrete has hardened sufficiently to be un-
marked by water falling on it.
(b) In lieu of sprinkling, an approved material for maintain-
ing a moist surface may be used.
17. Temperature of Concrete. Concrete, when deposited, shall
have a temperature of not less than 40° F., nor more than 120° F.
In freezing weather suitable means shall be provided for main-
taining the concrete at a temperature of at least 50° F. for not
less than 72 hours after placing, or until the concrete has thor-
oughly hardened. The methods of heating the material and pro-
tecting the concrete shall be approved by the engineer. Chem-
icals, or other foreign material, shall not be mixed with the
concrete for the purpose of preventing freezing unless approved
by the engineer.
¹ The time may be varied to suit local conditions.
7
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF ASPHALTIC CONCRETE
A.P.W.A.—B5-36
I. GENERAL
1. Asphaltic Base. The asphaltic base shall consist of a mineral
aggregate composed of coarse aggregate and fine aggregate, uni-
formly mixed with asphalt cement and shall have a compacted
thickness of ...... inches.
2. Requirements. All materials and methods of construction
shall conform to the requirements of these specifications.
II. MATERIALS
1. Coarse Aggregate. (a) The coarse aggregate for asphaltic
base mixture shall consist of broken stone, broken slag, mine-
tailings, or gravel. It shall be of reasonably uniform quality and
shall be free from dust and an excess of flat or elongated pieces.
Rock or mine-tailings from which it is produced shall have a per
cent of wear of not more than five (5). Slag from which it is
produced shall for each commercial size used weigh not less than
seventy (70) pounds per cubic foot. If gravel is used it shall be
composed of sound, hard, durable pebbles, free from clay or coat-
ings of any character.
(b) When tested by means of laboratory screens the coarse
aggregate, which may consist of one or more commercial products,
shall meet the following requirements: 1
Passing
2½-inch screen..
14-inch screen
1/4-inch screen
not less than
Per cent
95
25 to 75
0
Material which passes the 4-inch screen in such commercial
products shall in laboratory tests and for the purpose of propor-
tioning the mixture be considered as fine aggregate.
2. Fine Aggregate. (a) The fine aggregate for asphaltic base.
mixture shall consist of sand composed of clean, hard, durable
grains, free from clay, loam and other foreign matter, together
with particles which pass a 4-inch laboratory screen which may
be present in the coarse aggregate material. When tested by
1
¹ If a finer base material is desired, in 1,(b) change the figures 2½ inches
and 14 inches to 1½ inches and 34 inch, respectively.
B5
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
means of laboratory screens and sieves the sand or total fine B5
aggregate shall meet the following requirements:
Retained on
Passing
1/4-inch screen
1/4-inch screen
10-mesh sieve
40-mesh sieve
80-mesh sieve
200-mesh sieve
•
•
•
10-mesh sieve
40-mesh sieve
80-mesh sieve
200-mesh sieve
Per cent
100
0 to 20
15 to 50
25 to 65
7 to 40
0 to 6
3. Asphalt Cement. The asphalt cement shall be homogeneous,
free from water and shall not foam when heated to 175° C.
(347° F.). It shall meet the following requirements for physical
and chemical properties:
Specific gravity 25°/25° C. (77°/77° F.) not less than 1.0.
Flash point not less than 175° C. (347° F.).
Penetration at 25° C. (77° F.) 100 g., 5 sec., 40-70.
(Between these limits the exact penetration within a 10-point
range shall be as directed by the engineer.)
Ductility at 25° C. (77° F.) not less than 30.
Loss at 163° C. (325° F.) 5 hours, not more than 3%.
Penetration of residue at 25° C. (77° F.), 100 g., 5 sec., as
per cent of original penetration, not less than 50%.
Per cent of total bitumen soluble in carbon tetrachloride not
less than 99%.
4. Sampling. (a) Approval of sources of supply of coarse and
fine aggregate under these specifications shall be obtained from
the engineer prior to delivery of material, and samples of each
shall be submitted as directed by the engineer.
(b) A one-pound sample of the asphalt cement that the con-
tractor proposes to use in his work, together with a statement
as to its source and character, must be submitted with his bid.
If the contractor proposes to prepare the asphalt cement at the
paving plant, then in lieu of the above, a one-pound sample each
of flux and refined asphalt must be submitted with his bid, to-
gether with a statement as to the source and character of each and
proportions in which they will be combined to produce the asphalt
cement which he proposes to use. No asphalt cement, flux, or
refined asphalt, other than that specified in his bid, shall be used
by any contractor except with the written consent of the engineer,
and provided that the asphalt cement used shall comply in all
respects with the requirements of these specifications.
5. Methods of Testing. Methods of testing shall be as follows:
(a) Per cent of wear of rock, mine-tailings, or slag, A. S. T. M.
Standard D2-33. When testing slag, 4000 cc. loose measure of the
size specified shall be used.
(b) Weight per cubic foot of broken slag, A. S. T. M. Standard
C29-27.
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(c) Screen test of coarse aggregate, A. S. T. M. Standard B5
D18-16.
(d) Sieve test of fine aggregate, A. S. T. M. Standard D7-27.
(e) Physical and chemical properties of asphalt cement:
Flash Point (open cup), A. S. T. M. Standard D92-33.
Penetration, A. S. T. M. Standard D5-25.
Ductility, A. S. T. M. Standard D113-35.
Volatilization, A. S. T. M. Standard D6-33.
Bitumen soluble in carbon tetrachloride, A. S. T. M.
Standard D165-27.
6. Preparation of Asphalt Cement. (a) The asphalt cement
shall be melted in kettles designed to secure uniform heating of
the entire contents and shall be brought to a temperature of
250° F. to 350° F.
(b) When refined asphalt is to be combined with a flux, the
mixture shall be thoroughly agitated until a homogeneous asphalt
cement of the required penetration is produced. The penetration
of the asphalt cement shall be tested at suitable intervals to insure
that it is maintained at a uniform consistency throughout the
period of use.
7. Preparation of Mineral Aggregate. (a) The coarse and fine
aggregates for asphaltic base mixture shall be dried and heated
at the paving plant in suitably designed revolving driers. They
shall be heated to a temperature of 225° F. to 350° F., as
determined on the mixing platform. The aggregates may be
simultaneously fed into the same drier but in such case they shall
immediately after heating be screened into coarse and fine aggre-
gate and stored in separate bins, except in plants where the aggre-
gates are proportioned and dried by the batch method.
(b) A registering pyrometer shall be installed at a suitable
point at the discharge end of the drier, with the registering device.
so located as to clearly indicate to the drum firemen the tempera-
ture of the mineral aggregate when discharged.
8. Preparation and Composition of Asphaltic Base Mixture.
(a) The coarse and fine aggregate for asphaltic base mixture shall
be measured separately and accurately either by weight or volume
for each batch to be mixed. The required quantity of hot asphalt
cement for each batch shall be measured by actual weighing with
scales attached to the asphalt-cement bucket. The mixture shall
be made in an approved twin pug or batch mixer by first charging
it with the coarse and fine aggregate. After these have been
thoroughly mixed the asphalt cement shall be added and the
mixing continued for a period of at least forty-five (45) seconds
or longer if necessary to produce a homogeneous mixture in which
all particles of the mineral aggregate are uniformly coated.
(b) The constituents of the asphaltic base mixture shall be com-
bined in such proportions as to produce a mixture conforming to
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
the following composition limits by weight: 2
Per cent
...15 to 45
Passing 2½-inch, retained on 1-inch screen.
Passing 114-inch, retained on 4-inch screen...15 to 45
Total of the above two grades..
Passing 1/4-inch screen...
.53 to 70
.25 to 40
Bitumen (asphalt cement soluble in carbon disul-
phide)
4 to 7
9. Paving Plant Inspection. For the verification of weights or
proportions and character of materials, and determination of
temperatures used in the preparation of the mixture, the engineer
or his authorized representatives shall have access at any time to
all parts of the paving plant.
10. Transportation of Mixture. The asphaltic base mixture
shall be transported from the paving plant to the work in tight
vehicles previously cleaned of all foreign materials and, when
directed by the engineer, each load shall be covered with canvas or
other suitable material of sufficient size to protect it from weather
conditions. No loads shall be sent out so late in the day as to inter-
fere with spreading and compacting the mixture during the day-
light unless artificial light satisfactory to the engineer is provided.
III. CONSTRUCTION
1. Placing Asphaltic Base Mixture. Prior to the arrival of the
asphaltic base mixture on the work, the prepared subgrade or
underlying course shall be cleaned of all loose and foreign ma-
terials. The mixture shall be delivered at a temperature of 225° F.
to 325° F. It shall be laid only when the prepared subgrade or
underlying course is dry or at least free from standing water and
only when weather conditions are suitable. Upon arrival on the
work it shall be dumped outside of the area on which it is to be
spread and shall then be immediately distributed into place by
means of hot shovels and spread with hot rakes in a uniformly
loose layer to correct depth. No more asphaltic base shall be
placed in advance of laying the surface course than can be covered
by one day's run of the paving plant on surface mixture.
2. Compacting Mixture. (a) While still hot the asphaltic base
mixture shall be thoroughly and uniformly compressed by a
power-driven roller weighing not less than ten (10) tons, except
that a tandem roller weighing not less than eight (8) tons may
be used if approved by the engineer. Rolling shall start longi-
tudinally at the sides and proceed toward the center of the pave-
ment, overlapping on successive trips by at least one-half the
width of the roller, until all roller marks are eliminated. The
motion of the roller shall at all times be slow enough to avoid
2 If a finer base material is desired, in 8(b) change the figures 2½ inches
and 14 inches to 1½ inches and 34 inch, respectively.
B5
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
displacement of the hot mixture, and any displacement shall at B5
once be corrected by the use of rakes and of fresh mixture where
required. Rolling shall proceed at an average rate not to exceed
two hundred (200) square yards per hour per roller, and shall con-
tinue until no further compression is possible. To prevent ad-
hesion of the asphaltic base mixture to the roller, the wheels shall
be kept properly moistened, but excess of either water or oil will
not be permitted.
(b) Along curbs, headers, and similar structures, and at all
places not accessible to the roller, the mixture shall be thoroughly
compacted with hot tampers.
(c) The surface of the mixture after compression shall be
smooth and true to the established crown and grade. Any mix-
ture which becomes loose or broken, mixed with dirt, or in any
way defective prior to laying the surface course, shall be removed
and replaced with fresh hot asphaltic-base mixture, which shall
be immediately compacted to conform with the surrounding area.
3. Joints. Placing of the asphaltic base shall be as nearly con-
tinuous as possible, and the roller shall pass over the unprotected
end of the freshly laid mixture only when the laying of the base
is to be discontinued for such length of time as to permit the
mixture to become chilled. In all such cases, including the forma-
tion of joints as hereinafter specified, provision shall be made for
the proper bond with new base mixture by cutting or trimming
back the joint so as to expose an unsealed or granular surface for
the full specified depth of the course. At the end of each day's
work on base mixture, joints shall be formed by laying and roll-
ing against boards of the thickness of the compacted mixture,
placed across the entire width of the pavement, or by such other
method as may be approved by the engineer. When the laying of
the asphaltic base is resumed, the exposed edge of the joint shall
be painted with a thin coat of hot asphalt cement or asphalt cement
thinned with naphtha, and the fresh mixture shall be raked against
the joint, thoroughly tamped with hot tampers, and rolled.
4. Protection of Asphaltic Base. If at the time of laying
asphaltic-base mixture side supports such as curbs, edgings, gut-
ters, or shoulders have not been constructed, planks of suitable
thickness shall be laid along each side of the pavement so as to
prevent the mixture from squeezing out under the roller. These
planks shall remain in place until final compaction has been ob-
tained. Sections of compacted mixture shall be kept clean and
as free from traffic as possible prior to laying the surface course.
5. Conditions Prior to Laying Surface Course. Immediately
before laying surface course the base shall be cleaned of all dirt
or other foreign material so as to present a uniformly rough or
granular appearance admitting of complete bond with the wearing
course. It shall preferably be warm when the surface course is
placed.
сл
5
I
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF TAR MACADAM
(Hot Penetration Type)
A.P.W.A.-B6-36
I. BASE COURSE
1. Depth. The lower course shall consist of coarse mineral
aggregate spread to a finished depth of inches. This course
shall be filled thoroughly with filler and rolled until smooth and
firm. No filler shall be left on the surface.
2. Coarse Aggregate. The coarse aggregate shall consist of
broken stone, mine tailings, or slag of reasonably uniform quality
throughout and free from dust, loam, clay or an excess of flat or
elongated pieces. Ninety-five per cent shall pass a three and one-
half (32) inch screen and not more than 15% shall pass a two and
one-half (22) inch screen.
3. Filler. The filler shall consist of stone or slag screenings or
sand, 95% of which shall pass a three-quarter (34) inch screen and
40% to 80% shall pass a one-quarter (4) inch screen.
II. WATERPROOFING COURSE
1. Coarse Aggregate. The waterproofing course shall be placed
on the base and shall consist of a layer of crushed stone which
shall pass a two and one-quarter (24) inch ring and be retained
on a one and one-quarter (14) inch ring, spread to a finished
depth of not less than two and one-half (22) inches.¹ This
course shall not be filled but shall be keyed thoroughly together
by rolling. The surface shall be left smooth and of even texture,
clean and free from dirt, clay, stone dust, or other material which
will prevent the easy penetration of the refined tar.
2. First Coat of Refined Tar. Refined tar, as hereinafter speci-
fied, heated to a temperature of not less than 200° F., and not
more than 275° F., shall be spread uniformly over the surface
when dry to the amount of not less than one and seven-tenths
(1 7/10) gallons, nor more than one and eight-tenths (1 8/10)
gallons to the square yard. The refined tar shall conform to the
following requirements:
(a) The refined tar shall be homogeneous, free from water,
and shall not foam when heated to 150° C. (302° F.).
¹ This size stone is best for trap rock or hard rock which does not break
under the roller. If limestone or other soft rock is used, a larger size stone
may be used to advantage.
B6
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(b) Its specific gravity at a temperature of 25° C. (77° F.) B6
shall be not less than 1.20 nor more than 1.30.
(c) When tested by means of the New York Testing Lab-
oratory float apparatus, the float shall not sink in water main-
tained at 50° C. (122° F.) in less than 140 seconds nor more than
170 seconds.
(d) Its bitumen as determined by its solubility in chemically
pure carbon disulphide at room temperature shall not be less than
75% nor more than 90%, and it shall not show more than 0.2%
ash upon ignition of the material soluble in carbon disulphide.
(e) When distilled according to the method prescribed by the
American Society for Testing Materials (A. S. T. M., D 20-30), it
shall yield no distillate at a temperature lower than 170° C. (338°
F.); not more than 10% by weight shall distill below 270° C.
(518° F.) and not more than 20% by weight shall distill below
300° C. (572° F.)
(f) The total distillate from the test made in accordance with
clause (e) shall have a specific gravity at a temperature of 25° C.
(77° F.) of not less than 1.03.
(g) The melting point, as determined in water by the cube
method, A. S. T. M. Standard D61-24, of the pitch residue remain-
ing after distillation to 300° C. (572° F.) in accordance with the
test described in clause (e) shall not be more than 75° C.
(167° F.).
Att
3. Three-Quarter-Inch Stone. Three-quarter (34) inch crushed
stone without dust, i. e., stone which shall pass a one and one-
quarter (14) inch ring and be retained on a one-half (2) inch
ring, shall be spread over the surface, filling the voids but leaving
none on the surface. This course shall then be rolled until firm.
III. ROLLER
The roller used shall be a power roller of a type suitable for
macadam road construction and shall weigh 10 to 15 tons.
IV. PREPARATION FOR LAYING SURFACE COURSE
The road shall be swept free from any particles of stone not
held by the refined tar.
1. For Bituminous Surface. If the wearing course is to be
sheet asphalt or bituminous concrete the waterproofing course
shall be finished as follows:
(a) Second Coat of Refined Tar. Not less than one-half (2)
nor more than three-quarters (34) of a gallon of refined tar to the
square yard, heated to a temperature of not less than 200° F.,
nor more than 275° F. shall be spread over the surface of the
waterproofing course, and covered with stone screenings or
sharp sand. The road shall then be rolled until compacted. All
loose screenings or sand shall be swept off, and the wearing
course shall be laid directly on the completed waterproofing
course.
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
2. For Block Pavement. If the wearing course is to be a block B6
pavement, a sand-tar cushion, as hereinafter specified, shall be
laid over the completed foundation.
(a) Sand-Tar Cushion. Upon the completed foundation course
shall be spread a course 3/4-inch thick, of sand, mixed with refined
tar for surface treatments, as hereinafter specified, in the propor-
tion of 90% sand and 10% refined tar, by volume. The sand
shall be clean and dry and shall be mixed with the refined tar
until uniform, homogeneous mixture is obtained. It shall then
be spread on the foundation course, and shaped to a true surface
parallel to the surface of the finished pavement.
(b) Refined Tar for Sand-Tar Cushion. The refined tar for
cushion shall conform to the following requirements:
Its specific gravity at 25°/25° C. (77°/77° F.) shall not be
less than 1.10 nor more than 1.18.
When tested by means of the Engler Viscosimeter at 40° C.
(104° F.) the specific viscosity of the first 50 cubic centimeters
passing the orifice of the viscosimeter shall be not less than 10
nor more than 35, with a maximum range not exceeding 5.
Its bitumen, as determined by its solubility in chemically
pure carbon disulphide at room temperature, shall be not less
than 90%.
When distilled according to the American Society for Test-
ing Materials Standard Method (D 20-30) it shall yield not
more than 5% of distillate at a temperature lower than 170° C.
(388° F.); not more than 30% shall distill below 270° C. (518°
F.) ; and not more than 40% shall distill below 300° C. (572° F.).
3
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF TAR MACADAM
(Cold Penetration Type)
A.P.W.A.-B7-36
I. BASE COURSE
1. Depth. The lower course shall consist of coarse mineral
aggregate spread to a finished depth of inches. This course
shall be filled thoroughly with filler and rolled until smooth and
firm. No filler shall be left on the surface.
2. Coarse Aggregate. The coarse aggregate shall consist of
broken stone, mine tailings, or slag of reasonably uniform quality
throughout and free from dust, loam, clay, or an excess of flat or
elongated pieces. Ninety-five per cent shall pass a three and one-
half (32) inch screen and not more than 15% shall pass a two
and one-half (22) inch screen.
3. Filler. The filler shall consist of stone or slag screenings or
sand, 95% of which shall pass a three-quarter (34) inch screen
and 40% to 80% shall pass a one-quarter (4) inch screen.
II. WATERPROOFING COURSE
1. Coarse Aggregate. The waterproofing course shall be
placed over the base thus prepared and consist of a layer of stone
which will pass a two and one-quarter (24) inch ring, and be
retained on a one and one-quarter (1) inch ring, spread to a fin-
ished depth of not over three (3) inches. This stone shall be
rolled dry until it is thoroughly locked together and shows no
movement under the roller and shall be even and true to the
lines, grades and cross-sections.
2. Filling. The filler shall be broken stone or broken slag
screenings, or sand, and be rolled into the stone by spreading in
light even applications over the surface, keeping the roller pass-
ing back and forth and adding more filler as it rattles into the
voids, and continuing these operations until the filler is flush with
the surface of the stone; to be done without water. When the
voids are filled, water shall be used and more filler added as
needed to bring it flush with the surface of the stone. If sand is
used for the filler, slag or stone screenings may be used with
the water to finish up. Sufficient filler and water to form the
usual grout or to cover the stone shall not be used. Traffic shall
be kept off the road while it is drying out and any excess of filler
B7
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
on the surface shall be swept off, so that the stone shall be ex-
posed.
B7
3. Applying Refined Tar. When the road is dry, one gallon of
refined tar, as hereinafter specified, per square yard, or more if
the road will absorb it, shall be applied in two or more uniform
applications. Each application shall be allowed to penetrate
until there is no excess bitumen on the surface of the road before
making additional application.
4. Covering and Rolling. The covering material shall be either
clean, dry sand, or granulated slag. The covering shall be spread
within two to four hours after the last application of refined tar,
and enough used to prevent the roller from picking up the binder.
The foundation shall then be thoroughly rolled. At the con-
clusion of the rolling the refined tar shall just show through the
cover.
III. ROLLER
The roller used shall be a power roller of a type suitable for
macadam road construction and shall weigh ten (10) to fifteen
(15) tons.
IV. PREPARATION FOR LAYING SURFACE COURSE
1. For Bituminous Surface. If the wearing course is to be
sheet asphalt, it shall be laid on this foundation.
2. For Block Pavement. If the wearing course is to be a block
pavement, a sand-tar cushion, as hereinafter specified, shall be
laid over the completed foundation.
(a) Sand-Tar Cushion. Upon the completed foundation course
shall be spread a course three-quarters (34) inch thick of sand,
mixed with refined tar as hereinafter specified, in the proportion
of 90% sand and 10% refined tar, by volume. The same shall be
clean and dry and shall be mixed with the refined tar until a uni-
form, homogeneous mixture is obtained. It shall then be spread
on the base course and shaped to a true surface parallel to the
surface of the finished pavement.
V. REFINED TAR FOR BASE AND CUSHION
1. Requirements. The refined tar for base and cushion shall
conform to the following requirements:
(a) Its specific gravity at 25°/25° C. (77°/77° F.) shall not
be less than 1.10 nor more than 1.18.
(b) When tested by means of the Engler Viscosimeter at 40°
C. (104° F.) the specific viscosity of the first 50 cc. passing the
orifice of the Viscosimeter shall be not less than 10 nor more than
35 with a maximum range not exceeding 5. Low specific vis-
cosities should be used for work in the northern states and high
specific viscosities for work in the southern states.
(c) Its bitumen, as determined by its solubility in chemically
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
pure carbon disulphide at room temperature shall not be less B7
than 90%.
(d) When distilled according to the American Society for
Testing Materials Standard Method (D 20-30) it shall yield not
more than 5% of distillate at a temperature lower than 170°
C (338° F.), not more than 30% shall distill below 270° C.
(518° F.); and not more than 40% shall distill below 300° C.
(572° F.).
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF RECONSTRUCTED BRICK, BLOCK, OR
CONCRETE PAVEMENT
A.P.W.A.-B8-36
I. GENERAL
1. The old pavement of brick, block, or Portland cement con-
crete shall, where shown on the plans, be made to serve as a base
course by filling all depressions, having a depth of three-quarters
(34) inch or more, with asphaltic concrete compacted so as to
produce a surface conforming as closely as possible to the grades
and cross-sections shown on the plans.
2. All materials and methods shall conform to the requirements
of these specifications.
II. PREPARATION OF EXISTING PAVEMENT
The old pavement shall be thoroughly examined for any faulty
or weak condition in the old foundation or surface. All weak and
unsatisfactory places in the old foundation shall be removed.
The subgrade shall be compacted and the holes filled with Port-
land cement or asphaltic concrete foundation material to the
grade of the proposed foundation. Where the depth to subgrade
is more than six (6) inches the holes may be partly filled with
thoroughly compacted earth to allow for not more than six (6)
inches of foundation material. All loose bricks or blocks shall be
removed, together with the cushion coat, and the holes thor-
oughly cleaned and filled with asphaltic concrete material. In the
case of brick or block pavements a power-driven roller weighing
not less than seven (7) tons shall be used to detect loose brick or
blocks. Every third course of brick surface or block shall be
chipped until the surface presents to the engineer a roughness
satisfactory to receive the bituminous surface.
Where shallow gutters occur due to wearing down of crown
of old pavement it may be necessary to remove the old surface for
a width of five (5) feet adjacent to the curb and build up with
asphaltic concrete or binder. Pavement adjacent to car tracks
often presents particular problems. The engineer should there-
fore consider this specification as of a general nature and not a
complete set of requirements in any particular case. Such special
work should be indicated on plans.
mania
III. PLACING AND COMPACTING ASPHALTIC CONCRETE
The surface of the old pavement, thus prepared, shall be
B8
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
broomed to remove all dirt and all depressions shall be thor- B8
oughly cleaned. Joints shall be cleaned of dirt or loose material
to a depth of not over one-half (%) inch. All depressions ex-
tending more than three-quarters (34) inch below the established
base level shall be filled in with asphalt binder, asphaltic con-
crete, or asphalt macadam, depending on the type of surface to be
laid, to the established base level and thoroughly compacted with
hot tampers and then rolled with a power-driven roller weighing
not less than seven (7) tons until no further compression is pos-
sible. Any patches showing excess asphalt cement or becoming
loose, broken, or mixed with dirt or in any way defective shall be
removed or replaced with fresh material and immediately com-
pacted as above.
2
:
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
PAVEMENT FOUNDATION
OF ASPHALT MACADAM
(Penetration Type)
A.P.W.A.-B9-36
I. GENERAL
1. General Method of Construction. The asphalt macadam
base shall consist of two courses of mineral aggregate and asphalt
cement, combined as hereinafter specified, and having a total
compacted thickness of not less than six (6) inches. The bottom
course shall have a compacted thickness of not less than three
and one-half (32) inches and the second course shall have a
compacted thickness of not less than two and one-half (2½)
inches. The method of construction shall proceed substantially
as follows:
(a) A layer of No. 1 coarse aggregate, rolled to the thickness
of the bottom course, shall be treated with hot asphalt cement as
hereinafter specified.
(b) A layer of No. 2 coarse aggregate shall then be laid, rolled
to the thickness of the second course, and treated with hot asphalt
cement as hereinafter specified.
(c) If a sheet asphalt or fine graded aggregate asphaltic con-
crete surface course is to be laid directly upon the asphalt
macadam base, the surface voids in the base course shall be filled
by applying and rolling in sufficient intermediate aggregate.
The use of intermediate aggregate shall be omitted if an asphalt
macadam, coarse graded aggregate asphaltic concrete, or binder
course is to be laid directly upon the asphalt macadam base.
2. All materials and methods of construction shall conform
to the requirements of these specifications.
II. MATERIALS
1. Mineral Aggregate. (a) The mineral aggregate shall con-
sist of broken stone, mine tailings, or slag. It shall be of reason-
ably uniform quality throughout and shall be clean and free
from dust and an excess of flat or elongated pieces. Broken stone
or mine tailings from which it is produced shall have a per cent of
wear of not more than eight (8). Slag from which it is produced.
shall weigh not less than sixty-five (65) pounds per cubic foot
for each size specified.
(b) When tested by means of laboratory screens the coarse
and intermediate aggregate shall meet respectively the following
B9
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
requirements and be uniformly graded between the limits given: B9
Per cent passing screen
3½" 2½" 14" 1" 3/4" 1½"
Size
Name
No. 1. Coarse Aggregate
2½″ - 32″.
No. 2. Coarse Aggregate
14″ - 2½″.
Intermediate
½" - 1".......
.95-100 0-15
95-100 0-15
95-100 25-75 0-15
2. Asphalt Cement. The asphalt cement shall be homo-
geneous and free from water and shall not foam when heated to
175° C. (347° F.). It shall meet the following requirements:
Flash Point, not less than 175° C. (347° F.)
Penetration at 25° C. (77° F.) 100 g. 5 sec. 85 to 150. (Be-
tween these limits the engineer shall specify as desired; 85 to
100, 100 to 120 or 120 to 150)
Ductility at 25° C. (77° F.) not less than 30.
Loss at 163° C. (325° F.) 5 hours, not more than 3%. Pene-
tration of residue at 25° C. (77° F.) 100 g. 5 sec. as per cent of
original penetration, not less than 60%.
Proportion of bitumen soluble in carbon tetrachloride, not less
than 99%.
3. Sampling. (a) Approval of sources of supply of mineral
aggregate under these specifications shall be obtained from
the engineer prior to delivery of material, and samples of
each size specified shall be submitted as directed by the engineer.
(b) A one-pound sample, accompanied by an analysis, of the
asphalt cement that the contractor proposes to use in his work,
must be submitted with his bid. No asphalt cement, other than
that submitted with his bid, shall be used by any contractor ex-
cept with the written consent of the engineer.
4. Methods of Testing. Methods of testing shall be as follows:
(a) Per cent of wear of broken stone or mine tailings,
A. S. T. M. Standard Test D2-33.
(b) Weight per cubic foot of broken slag, A. S. T. M. Stand-
ard Test C29-27.
(c) Screen test of Coarse and Intermediate Aggregate,
A. S. T. M. Standard Test D18-16.
(d) Physical and Chemical properties of Asphalt Cement:
Flash Point (open cup), A. S. T. M. Standard Test D92-33.
Penetration, A. S. T. M. Standard Test D5-25.
Ductility, A. S. T. M. Test D113-35.
Volatilization, A. S. T. M. Standard Test D6-33.
Bitumen soluble in Carbon Tetrachloride, A. S. T. M. Stand-
ard Test D165-27.
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
III. CONSTRUCTION
1. Spreading Coarse Aggregate. The No. 1 coarse aggregate
shall be spread upon the prepared subgrade or sub-base course in
a uniformly loose layer of correct thickness. Each load or pile
shall be spread outside of the area upon which it is dumped, or by
means of approved spreading devices, in such manner that segre-
gation of sizes is prevented and uniform compaction may be se-
cured. Suitable precautions shall be taken to prevent the aggre-
gate from becoming mixed or coated with dirt or other objection-
able matter before and after spreading.
2. Compacting Coarse Aggregate. The No. 1 coarse aggregate
shall then be dry rolled with a power-driven roller, weighing not
less than ten (10) tons. Rolling shall start longitudinally at the
sides and proceed toward the center of the pavement, overlapping
on successive trips by at least one-half of the width of the rear roll.
The compacted aggregate shall possess a firm, even surface, true
to the grade and cross-sections shown on the plans, and present
a texture which will allow of uniform penetration of the asphalt
cement. If any irregularities appear during or after rolling they
shall be remedied by loosening the surface and removing or add-
ing No. 1 coarse aggregate, as may be required, after which the
area disturbed, including the surrounding surface, shall be rolled
until satisfactorily compacted to a uniform surface. All No. 1
coarse aggregate which becomes coated or mixed with dirt or
foreign substances prior to the application of asphalt cement
shall be removed and replaced with clean aggregate of the same
kind, and compacted as specified.
3. First Application of Asphalt Cement. Upon the rolled ag-
gregate, hot asphalt cement shall be uniformly applied at the rate
of from one and one-quarter (114) to one and one-half (1) gal-
lons per square yard as directed by the engineer. Asphalt cement
shall be applied only when the course is thoroughly dry for its
entire depth, and unless otherwise permitted by the engineer,
when the air temperature in the shade is at least 45° F. Applica-
tion of the asphalt cement shall be made by means of a pressure
distributor as described in paragraph 5 or with hand-pouring pots
as described in paragraph 6.
4. Heating. The asphalt cement shall be heated in kettles or
tanks designed to secure uniform heating of the entire contents,
and immediately prior to application shall be brought to a tem-
perature of 275° F. to 350° F. as directed by the engineer. The
contractor shall provide all necessary facilities for determining
the temperature of the asphalt cement during heating and prior
to application.
5. Pressure Distributor. The pressure distributor used for
applying asphalt cement shall be so designed and operated as to
distribute the asphalt cement in a uniform spray without atomi-
zation, in the amount and between the limits of temperature
B9
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
specified. Suitable means for accurately determining the tem- B9
perature of the asphalt cement shall be provided. The distributor
shall be so designed that the normal width of application shall be
not less than six (6) feet, with provision for the application of
lesser widths when necessary. If provided with heating attach-
ments, the distributor shall be so equipped and operated that the
asphalt cement shall be circulated or agitated throughout the
entire heating process. In order to prevent lapping at the end
junction of two applications, the distributor shall be promptly
shut off and, if necessary to prevent dripping, a drip pan shall
be inserted under the nozzles when the application begins to thin
just before the tank is emptied. Before continuing application
with a new load of asphalt cement, building paper shall be spread
over the treated surface for a sufficient distance back so that the
sprayers are operating at full force when the uncovered surface
is reached. The building paper shall then be removed and de-
stroyed. A narrow spout pouring pot, or hose attachment to the
distributor, shall be used to apply asphalt cement necessary to
touch up all spots unavoidably missed by the distributor.
6. Hand Pouring Pots. Hand-pouring pots used for applying
asphalt cement shall have a capacity of not less than three (3)
gallons and shall be equipped with slotted spouts so placed that
when the pot is emptied by carrying it forward with the end
of the spout close to the road surface the width of application
shall be not less than eight (8) inches. Each pot shall be fitted
with a gauge mark for accurately measuring the charge of as-
phalt cement before it is distributed. The distance to be covered
by each charge shall be measured off and the pouring operation
conducted so that the rate of application will be uniform as the
pot is emptied. The direction of successive pourings shall be re-
versed. Application shall be made at such angle to the center line
of the road, or longitudinally, as directed by the engineer. Dur-
ing pouring, the spout of the pot shall be kept within six (6)
inches of the surface of the road. The distributor slots shall be
kept free from obstructions and shall be cleaned as necessary to
insure a uniform distributing aperture. A narrow spout pouring
pot shall be used to apply asphalt cement necessary to touch up
all spots missed during the original application.
7. Second Course. Upon the bottom course, prepared as pre-
viously specified, No. 2 coarse aggregate shall be spread in a
uniformly loose layer of correct thickness, rolled and treated with
asphalt cement exactly as specified for bottom course, except that
if hand-pouring pots are used for applying the asphalt cement the
lines of distribution shall cross those of the first application at
an angle of approximately 90 degrees.
8. Filling Surface Voids with Intermediate Aggregate. If, in
accordance with Sec. I, 1 (c), the surface voids are to be filled, after
the application of asphalt cement to the second course and if prac-
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
ticable while it is still warm, a thin layer of dry, intermediate B9
aggregate shall be broadcast over the treated surface in such
quantity as to fill the surface voids and just cover the treatment.
It shall then be broomed, if necessary, to break up all clumps and
produce a uniform covering, after which the base shall be rolled
until thoroughly compacted and bonded. Suitable precautions
shall be taken to prevent the distribution of intermediate aggre-
gate over any portion of the coarse aggregate which has not
received the first application of asphalt, and in no case shall it be
dumped directly upon either the treated or untreated coarse ag-
gregate.
9. Conditions Prior to Laying Binder or Surface Course. Im-
mediately before laying binder or surface course, the base shall
be cleaned of all loose or caked broken stone, dirt, or other fine
material so as to present a uniformly rough or granular appear-
ance admitting of complete bond with the binder or wearing
course.
5
¿
*
DATE DUE
1

STANDARD SPECIFICATIONS
FOR PUBLIC WORKS CONSTRUCTION
ArchPocbural
LILITO
TE
15
C-SIDEWALKS AND CURBS
C1-Concrete Sidewalks
C2-Stone, and Concrete Curbs
AMERICAN PUBLIC WORKS ASSOCIATION
CHICAGO, ILLINOIS
UNIVERSITY OF MUS
:
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
نعت
Specification for
CONCRETE SIDEWALKS
A.P.W.A.—C1-36
ARCHITECTURAL
LIBRARY
T
↓
Con
A 58
GENERAL REQUIREMENTS
These specifications apply to concrete sidewalks in residence
and business districts, and cover the preparation of the sub-base,
the laying and finishing of the walk, and its protection during
early hardening. Specific provisions covering the construction
of either one- or two-course sidewalks are given, following the
general requirements specified below.
I. MATERIALS
1. Cement. The cement shall meet the requirements of the
current Standard Specifications for Portland Cement of the
American Society for Testing Materials.
Removed by decantation
Coal...
2. Sources of Supply. Before delivery on the job and at such
times as the architect or engineer deems necessary, the con-
tractor shall furnish any samples he may require of the material
herein mentioned. These samples shall be tested and if found
to pass the requirements of the specifications, similar materials
shall be considered as acceptable for the work. In no case shall
aggregate containing frost or lumps of frozen material be used.
3. Fine Aggregate. (a) Fine aggregate shall consist of sand or
other approved inert materials with similar characteristics or a
combination thereof, having hard, strong, durable particles. The
amount of deleterious substances shall not exceed the following
percentage by weight:
Per cent
3
1
1
Clay lumps
Other local deleterious substances (such as shale,
alkali, mica, coated grains, soft and flaky particles)
Total coal, clay lumps, shale, soft fragments and other
local deleterious substances
5
(b) All fine aggregates shall be free from injurious amounts of
organic impurities. Aggregates shall be subjected to the colori-
metric test made in the field as follows:
Fill a 12 oz. graduated bottle to the 4½ oz. mark with the
sand to be tested. Add a 3% solution of sodium hydroxide.
until the volume, after shaking, amounts to 7 ounces. Shake
thoroughly and let stand for 24 hours. The sample shall then
C1
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
show a practically colorless solution, or at least, a solution not C1
darker than straw color.
(c) Fine aggregate shall be well graded from coarse to fine and
when tested by means of laboratory sieves, shall conform to the
following requirements:
Passing
3/8" sieve
No. 4 sieve
No. 16 sieve
No. 50 sieve
No. 100 sieve
•
..100
Removed by decantation.
Shale (removed by flotation test)
Coal
Per cent
These percentages are suggested as limiting percentages but
they may be altered within these limits to suit local conditions.
(d) Fine aggregate shall be of such quality that mortar com-
posed of one (1) part cement and three (3) parts fine aggregate by
weight, when made into briquets or cylinders, shall show a tensile
or compressive strength at seven (7) and twenty-eight (28) days
at least equal to the strength of briquets or cylinders similarly
made and proportioned with Ottawa sand.
85 to 100
45 to 80
2 to 30
0 to
to 5
4. Coarse Aggregate. (a) Coarse aggregate shall consist of
crushed stone, gravel, blast-furnace slag or other approved inert
material of similar characteristics or combinations thereof, hav-
ing hard, strong, durable pieces and free from adherent coatings.
The amount of deleterious substances shall not exceed the fol-
lowing percentage by weight:
General concrete ...
Concrete subject to abrasion
Per cent
.1.5
1
1
.0.5
1
•
Clay lumps
Soft fragments
Other local deleterious substances (such as alkali,
friable, thin, elongated, or laminated pieces)
Total shale, coal, clay lumps and soft fragments ....5
(b) Coarse aggregate shall be well graded from one (1) inch
down, 90 to 100% passing sieve with one (1) inch square open-
ings, 25 to 60% passing sieve with one-half (2) inch square
openings and not more than 10% passing screen having over one-
quarter (4) inch square openings.
(c) Blast-furnace slag that meets the grading requirements of
these specifications shall conform to the following minimum
weight requirements:
-
.65 lb. per cu. ft.
..70 lb. per cu. ft.
5. No. 1 Aggregate for Wearing Course. No. 1 aggregate for
the wearing course shall consist of clean, hard, tough, crushed
rock, pebbles, or blast-furnace slag, free from vegetable or other
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
organic matter and shall contain no soft, flat or elongated par- C1
ticles. It shall pass, when dry, a screen having one-half (½) inch
square openings, and not more than 10% shall pass a screen hav-
ing four (4) meshes per linear inch.
6. Bank-run or Mixed Aggregate. Bank-run or mixed aggre-
gate shall be composed of a combination of hard, strong, durable
particles of sand and gravel or other approved inert material of
similar characteristics or combinations thereof, containing not
more than 5% total deleterious substances. The proportion of
fine aggregate to coarse aggregate by volume shall not be less
than one to one and three-quarters (1:134) nor more than one to
one (1:1). When the amount of fine aggregate in the coarse
aggregate is out of proportion, it shall be corrected by screening
and remixing. Ninety (90) to 100% bank-run or mixed aggre-
gate shall pass a sieve with one (1) inch square openings. Mixed
aggregates prepared prior to properly supervised proportioning
shall not be used.
7. Material for Sub-base.
Durable material such as crushed
stone, bank-run gravel, blast-furnace slag, or steam-boiler cinders
shall be used in the sub-base. (Note:-Eliminate this clause un-
less sub-base is required.)
8. Water. Water shall be clean, free from acid, alkali, vege-
table, or other organic matter.
9. Color. If artificial coloring material is required, only those
mineral colors shall be used which, in the amount hereinafter
specified, will not appreciably impair the strength of the cement.
10. Reinforcement. The reinforcing metal shall meet the re-
quirements of the current Standard Specifications for Steel Re-
inforcement of the American Society for Testing Materials. It
shall be free from excessive rust, scale, paint, or coating of any
character which will tend to reduce or destroy the bond. The re-
inforcement shall have a weight of not less than twenty-one (21)
pounds per hundred (100) square feet.
<
11. Joint Filler. The joint filler shall be of a suitable elastic
waterproof compound that will not become soft and run out in
hot weather, nor hard and brittle and chip out in cold weather, or
prepared strips of fiber matrix and bitumen as approved by the
architect or engineer. The strips shall be one-half (½) inch in
thickness, their width shall at least equal the full thickness of
the slab and their length shall at least equal the width of the slab
at the joint.
II. SUBGRADE
1. Preparation. (a) All soft and spongy places shall be re-
moved and all depressions filled with suitable material which
shall be thoroughly compacted in layers not exceeding six (6)
inches in thickness. The subgrade shall be thoroughly tamped
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
until it is brought to a firm, unyielding surface. It shall have a C1
transverse slope of not more than one-half (½) inch per foot.
(b) When the concrete sidewalk is to be constructed over an
old path composed of gravel or cinders, the old path shall be
entirely loosened, the material spread for the full width of the
subgrade and compacted as specified.
2. Deep Fills. All fills shall be made in the manner satis-
factory to the architect or engineer. The use of muck, quicksand,
soft clay, spongy or perishable material is prohibited. The top
of all fills shall extend beyond the walk on each side at least one
(1) foot, and the sides shall have a slope of at least one (1) on one
and one-half (1½).
3. Drainage. When required, a suitable drainage system shall
be installed and connected with sewers or other drains indicated
by the architect or engineer.
4. Depth. The subgrade shall be not less than
(......) inches below the finished surface of the walk.
Note. Subgrade to be at least five (5) inches below the finished surface of
the walk when the sub-base is not required and at least eleven (11) inches below
when sub-base is required.
Kata
III. SUB-BASE
(Omit these sections unless sub-base is required.)
1. Thickness. On the subgrade shall be spread a material as
hereinbefore specified which shall be thoroughly rolled or tamped
to a surface at least
(......) inches below the fin-
ished grade of the walk. On fills, the sub-base shall have the
same slope as the sides of the fill.
•
2. Wetting. While compacting the sub-base, the material
shall be kept thoroughly wet, and shall be wet when the concrete
is deposited but shall show no pools of water.
IV. FORMS
1. Materials. Forms shall be free from warp and of sufficient
strength to resist springing out of shape.
2. Setting. The forms shall be well staked or otherwise held.
to the established lines and grades and their upper edges shall
conform to the established grade of the walk.
3. Division Plates. Suitable metal division plates shall be
provided to completely separate adjacent slabs during con-
struction unless otherwise permitted by the architect or engineer.
4. Treatment. All wood forms shall be thoroughly wetted
and metal forms oiled or coated with soft soap or whitewash be-
fore depositing any material against them. All mortar and dirt
shall be removed from forms that have been previously used.
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
V. CONSTRUCTION
1. Size of Slabs. The slabs or independently divided blocks
when not reinforced shall have an area of not more than one
hundred (100) square feet. Length of slab shall be equal to the
width and all slabs exceeding one hundred (100) square feet in
area shall be reinforced.
2. Thickness of Walk. Minimum thickness to be four (4)
inches.
3. Joints. A one-half (½) inch joint shall be provided at least
once every fifty (50) feet in the length of the walk, which shall
be filled with suitable material as specified under "Joint Filler."
A similar joint shall be provided at each intersection of sidewalk.
and street curb and each intersection of sidewalk with concrete
driveway. Sidewalks in business districts shall be separated
from abutting buildings by a one-half (2) inch joint.
4. Protection of Edges. The upper edges of the slabs shall be
rounded to a radius of one-half (½) inch. The edges of all slabs
abutting a business street which act as curbing shall be rounded
to a radius of one and one-half (1½) inch.
VI. MEASURING AND MIXING
1. Measuring. The method of measuring the materials for
the concrete or mortar, including water, shall be one which will
insure separate and uniform proportions of each of the materials.
at all times. A sack of Portland cement (94 pounds net) shall be
considered one (1) cubic foot.
2. Machine Mixing. All concrete shall be mixed by machine.
except when the architect or engineer shall otherwise permit
under special conditions. A batch mixer of any approved type
shall be used. The ingredients of the concrete or mortar shall be
mixed to the specified consistency, and the mixing shall continue
for at least one (1) minute after all materials are in the drum.
The drum shall be completely emptied before receiving material
for the succeeding batch.
3. Central Mixing Plants. (a) All concrete ingredients shall
comply in all respects with the requirements for materials speci-
fied hereinbefore.
(b) Measurement. Cement shall be measured by weight or in
a full bag. When the cement is measured by weight, it shall be
weighed on a scale separate from those used for the other mate-
rials; when the cement is measured in bags, no fraction of bags
shall be used.
Coarse aggregates shall be measured by weight. Fine aggre-
gates shall be measured by weight or by inundated volume in
a device satisfactory to the engineer.
Water shall be measured by volume or by weight.
Powdered admixtures shall be measured by weight and liquid
admixtures by weight or volume.
·
C1
5
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(c) Mixing. The mixing equipment shall be capable of mixing C1
the aggregates, cement, and water within the specified time into
a thoroughly mixed and homogeneous mass which can be dis-
charged without segregation.
In the case of stationary mixers, the mixer drums shall be of
adequate size to accommodate the maximum batch, and shall be
in accordance with the Concrete Mixer Standards adopted by the
Mixer Manufacturers' Bureau of Standards adopted by the Asso-
ciated General Contractors of America. The mixer drum shall be
rotated at the rate specified by its manufacturer.
When the control mixing plant is depended upon for the com-
plete mixing, the minimum mixing time for mixers of one (1)
cubic yard capacity or less shall be one (1) minute; for larger
capacities of mixers this mixing time shall be increased at the
rate of one-quarter (4) minute for each cubic yard or less addi-
tional capacity. When the concrete is transported in an agitator
truck provided with mixing blades, the mixing time at the central
mixer may be reduced to the minimum required to incorporate
the ingredients of the mix into a mass and the mixing completed
in the agitator; under these circumstances each batch of concrete
shall be mixed in the agitator for fifty (50) revolutions or more.
(d) Delivery. Concrete shall be delivered to the work at
the consistency specified, and shall be hauled in a water-tight con-
tainer in which segregation will not take place and from which the
concrete can be discharged freely.
Concrete shall be delivered to the site of the work and dis-
charge from the hauling container begun within a period of one
and one-half (12) hours after the introduction of the mixing
water to the dry materials.
Concrete delivered in out-door temperatures lower than 40° F.
shall arrive at the work having a temperature not less than 60° F.,
nor greater than 100° F., unless otherwise specified by the engi-
neer.
(e) Inspection. Proper facilities shall be provided for the
engineer to inspect and sample the concrete at the mixing plant,
loading plant, and point of delivery.
4. Hand Mixing. When it is necessary to mix by hand, the
materials shall be mixed dry on a water-tight platform until the
mixture is of uniform color, the required amount of water added,
and the mixing continued until the mass is of proper consistency
and homogeneous.
5. Retempering. Retempering of mortar or concrete which
has partially hardened, that is, remixing with or without addi-
tional materials or water, shall not be permitted.
VII. PROTECTION
1. Treatment and Curing. As soon as the finished walk has
hardened sufficiently to prevent damage, the surface of the walk
6
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
shall be sprinkled with water or preferably covered with sand or C1
earth and, in either case, kept wet for at least three (3) days.
When permitted by the architect or engineer, a chemical curing
agent may be used, provided it is applied according to the man-
ufacturer's specifications.
When desired by the architect or engineer, high early strength
or quick-setting cement may be used and the curing period
reduced to twenty-four (24) hours.
2. Additional Protection. The freshly finished walk shall be
protected from hot sun and drying winds until it can be sprinkled
or covered as above specified. The concrete surface must not be
damaged or pitted by rain drops, and the contractor shall provide
and use, when necessary, sufficient tarpaulins to completely cover
all sections that have been placed within the preceding twelve
(12) hours. The contractor shall erect and maintain suitable bar-
riers to protect the walk from traffic and any section damaged
from traffic or other causes occurring prior to its official accept-
ance, shall be repaired or replaced by the contractor at his own
expense in a manner satisfactory to the architect or engineer.
Before the sidewalk is opened to traffic the covering shall be re-
moved and disposed of by the contractor. The walk shall not be
opened to traffic until the architect or engineer so directs.
3. Temperature Below 35 Degrees Fahrenheit. If at any time.
during the progress of the work the temperature is, or in the
opinion of the architect or engineer will, within twenty-four
(24) hours, drop to 35° F., the water and aggregates shall be
heated and precautions taken to protect the work from freezing
for at least five (5) days.
4. Name Stamp. The contractor shall mark in the walk at
each end of every one hundred and fifty (150) feet of walk or
fraction thereof, either by stamping or by inlaying an approved
metal plate, his name and the year in which the walk is con-
structed. The stamped letters shall be one (1) inch high and
one-fourth (4) inch deep. If a metal plate is used, the top of the
plate shall be flush with the top of the walk.
TWO-COURSE SIDEWALK
For two-course walks the following will apply in addition to the
general requirements.
I. CONCRETE BASE CONSTRUCTION
1. Proportions. The concrete shall be mixed in the proportions
by volume of one (1) part Portland cement, two and one-half
(22) parts fine aggregate and four (4) parts coarse aggregate. If
bank-run or mixed aggregate is permitted by the architect or
engineer, the proportions shall be one (1) part Portland cement
to six (6) parts bank-run or mixed aggregate. In either case, the
7
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
number of sacks of cement per cubic yard of concrete in place C1
shall not be less than five and one-half (5½).
2. Consistency. The materials shall be mixed wet enough to
produce a concrete of consistency that will flush readily under
slight tamping, but which can be handled without causing a sepa-
ration of the coarse aggregate from the mortar.
3. Placing. After mixing, the concrete shall be handled rapidly
and the successive batches deposited in a continuous operation
completing individual sections to the required depth and width.
Under no circumstances shall concrete that has partly hardened
be used. The forms shall be filled and the concrete struck off
and tamped to a surface the thickness of the wearing course.
below the established grade of the walk. The method of placing
the various sections shall be such as to produce a straight clean-
cut joint between them so as to make each section an independent
unit. If dirt, sand or dust collects on the base it shall be removed
before the wearing course is applied. Any concrete in excess of
that needed to complete a section at the stopping of work shall
not be used. In no case shall concrete be deposited upon a frozen
subgrade or sub-base.
4. Reinforcing. Slabs having an area of more than one hundred
(100) square feet, or having dimensions greater than ten (10) feet,
shall be reinforced with wire fabric or with plain or de-formed
bars. The reinforcement shall be placed two (2) inches below the
finished surface of the walk. It shall not cross joints and shall be
lapped sufficiently to develop the full strength of the metal.
II. WEARING COURSE CONSTRUCTION
1. Proportions for Residence Districts (Mixture No. 1). The
wearing course shall be mixed in the proportions of one (1) sack
of Portland cement and two (2) cubic feet of fine aggregate. The
minimum thickness shall be one-half (½) inch.
Alternate: One (1) inch depth of sheet asphalt (A. P. W. A.
Specification, G1-36, Sheet Asphalt Pavement) may be filled in
to replace the concrete wearing course to within six (6) inches of
the sides of the walk.
2. Proportions for Business Districts (Mixture No. 2). The
wearing course shall be mixed in the proportions of one (1) sack
of Portland cement, one (1) cubic foot of fine aggregate and one
(1) cubic foot of No. 1 aggregate for wearing course. The
minimum thickness shall be one (1) inch.
3. Consistency. The mortar shall be the dryest consistency
possible to work with a sawing motion of the strike-board.
4. Placing. The wearing course shall be placed immediately
after mixing. It shall be deposited on the fresh concrete of the
base before the latter has appreciably hardened, and brought to the
established grade with a strike-board. In no case shall more than
8
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
forty-five (45) minutes elapse between the time the concrete for C1
the base is mixed and the wearing course is placed.
5. Finishing. After the wearing course has been brought to the
established grade by means of a strike-board, it shall be worked
with a wood float in a manner which will thoroughly compact it
and provide a surface free from depressions or irregularities of any
kind. When required, the surface shall be steel-troweled, but
excessive working shall be avoided. In no case shall dry cement
or a mixture of dry cement and sand be sprinkled on the surface
to absorb moisture or to hasten hardening. The entire sidewalk
shall be jointed or flagged in sections equal to the width of the
walk or as otherwise directed by the architect or engineer. All
markings shall be cut through the finishing coat with proper mark-
ing tools. All flag joints or outer edges shall be neatly rounded
and finished with special tools.
6. Coloring. If artificial coloring is used, it must be incorpo-
rated with the entire wearing course, and shall be mixed dry with
the cement and aggregate until the mixture is of uniform color.
In no case shall the amount of coloring exceed 5% of the weight
of the cement.
ONE-COURSE SIDEWALK
For one-course walks the following will apply in addition to the
general requirements.
I. CONSTRUCTION
1. Proportions. The concrete shall be mixed in the proportions
of one (1) part Portland cement, two (2) parts fine aggregate and
three (3) parts coarse aggregate. The number of sacks of cement
per cubic yard of concrete in place shall not be less than six and
one-half (62).
2. Consistency. The materials shall be mixed with sufficient
water to produce a concrete which will hold its shape when struck
off with a strike-board. The consistency shall not be such as to
cause a separation of the coarse aggregate from the mortar in
handling. The mix shall be sufficiently dry to eliminate the
pooling of water on the surface when struck off with a strike-
board.
3. Placing. After mixing, the concrete shall be handled rapidly
and the successive batches deposited in a continuous operation
completing individual sections to the required depth and width.
Under no circumstances shall concrete that has partly hardened be
used. The forms shall be filled and the concrete brought to the
established grade by means of a strike-board or straight-edge.
The method of placing the various sections shall be such as to pro-
duce a straight clean-cut joint between them, so as to make each
section an independent unit. Any concrete in excess of that
9
1.
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
needed to complete a section at the stopping of work shall not be C1
used. In no case shall concrete be deposited upon a frozen sub-
grade or sub-base.
4. Reinforcing. Slabs having an area of more than one hundred
(100) square feet, or having dimensions greater than ten (10)
feet, shall be reinforced with wire fabric or with plain or de-
formed bars. The reinforcement shall be placed two (2) inches
below the finished surface of the walk. The reinforcement shall
not cross joints and shall be lapped sufficiently to develop the full
strength of the metal.
5. Finishing. (a) After the concrete has been brought to the
established grade by means of a strike-board, it shall be worked
with a steel trowel or wood float to give the desired surface herein-
after specified. In no case shall dry cement or a mixture of dry ce-
ment and sand be sprinkled on the surface to absorb moisture or to
hasten hardening. The surface shall be flagged as hereinbefore
specified. Unless protected by metal the surface edges of all slabs
shall be rounded to a radius of one-half (½) inch.
(b) Alternate. The concrete shall be struck off flush with the
top of the forms and be given a true even finish with a wooden
float, care being taken that none of the coarse aggregate is ex-
posed.
Cross out the following sections except
Smooth Surface. The surface of the concrete shall be
troweled with a steel trowel to a smooth, even surface free
from depressions or irregularities of any kind. Excessive
working of the surface with the trowel shall be avoided.
Medium Rough Surface. The surface shall be floated with
a wooden float only, producing an even, gritty finish. On
wide sidewalks the finishing may be done with two applica-
tions of a canvas belt, not less than six (6) inches wide, and
about two (2) feet longer than the width of the sidewalk.
For the first application, the belt shall be drawn across the
surface with vigorous strokes at least twelve (12) inches long,
and moved ahead very slightly at each stroke. The second
application shall be given immediately after the water glaze
or sheen disappears, and the stroke of the belt shall be not
more than four (4) inches, while the longitudinal motion shall
be greater than during the first application.
(c) Types of Surface.
for the surface desired:
Rough Surface. The surface shall be floated with a wooden
float leveling all sags and producing an even surface. After
being floated in this manner the roughening shall be done by
slapping the surface of the concrete with the face of the float,
raising the float vertically from the concrete after each stroke.
10
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Specification for
STONE, AND CONCRETE CURBS
A.P.W.A.-C2-36
STONE CURB
I. MATERIALS AND DIMENSIONS
1. Granite. The curb shall be of straight split, medium grained
granite, of uniform texture and color, free from seams, excess of
mica and disintegration.
(a) If Set in Concrete the following dimensions are recom-
mended:
Length not less than four (4) feet.
Top width five (5) inches or as required, having in mind
the quarrying proportion of one-third (%) the depth. See
note below.
Bottom width should be not less than three (3) inches
rough squared.
Depth-For not less than three-fourths (34) of the length,
the depth should be sixteen (16) inches for a curb five (5)
inches wide.
Note. The granite splits more readily into shapes where the depth is three (3)
times the width.
(b) If Not Set in Concrete a special depth up to twenty (20) or
twenty-six (26) inches may be required, but in the interests of
simplified practice, the sixteen (16) inch depth should be ad-
hered to wherever good soil conditions permit.
2. Hard Sandstone. The curb shall be of best quality hard sand-
stone, uniform color, free from seams and laminations.
(a) If Set in Concrete the following dimensions are recom-
mended:
Length not less than thirty-six (36) inches nor more than
forty-two (42) inches.
Top width four, five, or six (4, 5, or 6) inches, as required.
Bottom width should be not less than one-half (2) the
width specified for the top.
Depth-For not less than three-fourths (34) of the length,
the depth should be sixteen (16) or eighteen (18) inches for
the five (5) or six (6) inch width respectively.
(b) If Not Set in Concrete a special depth up to twenty (20) or
twenty-five (25) inches may be required.
3. Bluestone and Limestone. Same as for Hard Sandstone, ex-
cept that the length may be from thirty-six (36) to forty-eight
(48) inches.
C2
1
·
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
4. Soft Sandstone and Limestone. As the softer stones are often C2
machine-cut or sawed, the dimensions need not be limited by
strata or natural cleavage, but for handling and laying they should
conform as follows:
(a) If Set in Concrete the following dimensions are recom-
mended:
Length not less than four (4) feet nor more than six (6)
feet.
Top width five (5) or six (6) inches.
Bottom width not less than top.
Depth-For a length not less than three-fourths (34) of
the top length, the depth should be sixteen (16) or eighteen
(18) inches for a five (5) or six (6) inch width respectively.
(b) If Not Set in Concrete a depth up to twenty-four (24) inches
may be required.
5. Header or Protection Curb. Header or protection curb
should have a depth of twelve (12) to fourteen (14) inches, a
width not less than four (4) inches and length not less than
twenty-four (24) inches. It shall be set in a concrete bed six
(6) inches deep and eighteen (18) inches wide and backed with
concrete to within eight (8) inches of its top on the paving side
and flush with the top on the unpaved or exposed side.
6. Methods of Testing. If a test is desired it shall be provided
for in the local specifications.
(a) Abrasion. The loss by abrasion shall be determined by the
"Rattler Test" in accordance with the A. S. T. M. specification
C7-30 for Brick or the "Deval Abrasion Test," A. S. T. M. specifi-
cation D2-33.
The rattler, abrasive charge, the test and record shall be as
described therein. Four blocks of the material to be tested shall
be axed or hammered to about 5x6x10 inches and dried (these
four (4) blocks will weigh from 110 to 120 pounds, approxi-
mating the weight of ten (10) brick). For the present a loss of
12% by abrasion will be permissible.
If made through the "Deval Abrasion Test," a co-efficient of
wear of seven (7) is permissible.
(b) Absorption. The dry blocks shall be weighed, then im-
mersed in water for forty-eight (48) hours, drained off for five (5)
minutes and then weighed. The increase in weight is the absorp-
tion and should not exceed 22%.
II. CONSTRUCTION
1. Dressing and Cutting. (a) The face shall be dressed to vary
not more than three-eighths (%) inch from a plane surface, for a
depth of twelve (12) inches from the top. The remainder of the
face shall be free from projections of more than one-half (2)
inch.
The back shall likewise be dressed parallel to the face for a
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
depth of one (1) inch from the top. The remainder of the back C2
shall be free from projections of more than one (1) inch.
The top shall likewise be dressed, having a bevel or rise of
one-quarter (4) inch from face to back of curb.
The ends shall likewise be dressed at right angles to the face
and top to vary not more than one-eighth (%) inch from a plane
surface for a depth of twelve (12) inches from the top.
(b) Circular Curb for round corners and closures shall meet
the above except as to length.
(c) Bull Nose or round edge curb is regarded as a special fea-
ture and entails extra cutting to meet local practice.
(d) Headers or Protection curb shall be dressed to a plane
surface on top, ends cut at right angles to the face and top to a
three-eighths (3%) inch joint for a depth of eight (8) inches.
(Note.—Except for special purposes the standard methods of dressing or cut-
ting as employed for the several kinds of stone are regarded as acceptable. Un-
necessary cost is incurred by specifying a particular method.)
2. Setting Curb. (a) Grading. Curb shall not be set until the
rough grade has been prepared and rolled, if the latter is specified.
(b) Temperature. Curb shall not be laid in concrete when there
is indication of freezing. If overtaken by temperature falling to
35° F., the concrete in place shall be covered with dirt from the
street or otherwise protected as the engineer directs.
3. Setting Curb in Concrete. (a) Curb Trench. The curb
trench on unpaved streets should be eighteen (18) inches wide,
six (6) inches in front of the curb and twelve (12) inches back
from the face of curb. The curb trench on paved streets should be
at least twelve (12) inches wide measured from the face of the
curb. It should be at least twenty-two (22) inches deep. If the
back of the trench suggests caving in, it should be held with planks
so as to insure the full width of concrete throughout its depth, with
square shoulder at the top.
(b) Concrete. All concrete ingredients shall comply in all re-
spects with the requirements for materials hereinafter specified.
The concrete for embedment shall be mixed in the proportions by
volume of one (1) part Portland cement, three (3) parts fine ag-
gregate and six (6) parts coarse aggregate. If bank-run or mixed
aggregate is permitted by the architect or engineer, the propor-
tions shall be one (1) part Portland cement to eight (8) parts
bank-run or mixed aggregate.
The concrete shall be spread in the trench not more than ten
(10) feet in advance of placing the curb. As soon as the curb
is bedded to its true line and grade, the trench shall be filled in
back of the curb to within six (6) inches of the top of the curb
and on unpaved streets to the bottom of proposed pavement in
front of the curb. The concrete shall be tamped or spaded so as
not to disturb the curb. The remainder of the trench back of the
curb shall be backfilled with dirt or specified material to the top
of the curb.
3
•
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
4. Concrete Embedment Eliminated. Where soil conditions C2
permit, the architect or engineer may eliminate the concrete em-
bedment.
5. Drain Tile. (a) If drain tile is required, the bottom of the
trench should be thirty-six (36) inches below the top of the curb,
and at least six (6) inches wide. The tile should be a commercial
size, not less than three (3) or four (4) inches inside diameter.
It shall be laid to line and grade and connected by vitrified tile,
closed joints, to sewers or catch-basins. If outlet is available it is
best to make these connections about three hundred (300) feet
apart. The tile shall be covered with screened gravel or broken
stone, none of which shall pass a one-half (½) inch screen (the
coarse aggregate for concrete may be used). This covering shall
be carried up to the bottom of the curb trench; thus it will be four-
teen (14) inches deep.
(b) If, however, drain tile is not required, the curb trench may
be of such depth and may be drained off as local conditions sug-
gest.
CONCRETE CURB
I. GENERAL
1. Dimensions. The standard cross-section for straight curb
shall be at least six (6) inches at the top, eight (8) inches at the
bottom and sixteen (16) inches in depth, provided in no case.
shall the depth be less than the thickness of the pavement plus
the height above the gutter. The top corner on the face of the
curb shall be rounded to a radius of at least one (1) inch and the
top corner on the back of the curb shall also be neatly rounded
with special tools.
II. MATERIALS
1. Cement. The cement shall meet the requirements of the cur-
rent standard specifications for Portland cement of the American
Society for Testing Materials.
2. Fine Aggregate. (a) The fine aggregate shall consist of sand
or other approved inert materials with similar characteristics or a
combination thereof, having hard, strong, durable particles. The
amount of deleterious substances shall not exceed the following
percentage by weight:
Removed by decantation.
Coal
Clay lumps
Other local deleterious substances (such as shale,
alkali, mica, coated grains, soft and flaky particles)...
Total coal, clay lumps, shale, soft fragments and other
local deleterious substances.
5
Per cent
3
1
1
•
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(b) All fine aggregates shall be free from injurious amounts of C2
organic impurities. Aggregates shall be subjected to the colori-
metric test made in the field as follows:
Fill a 12 oz. graduated bottle to the 4½ oz. mark with sand to
be tested. Add a 3% solution of sodium hydroxide until the
volume, after shaking, amounts to 7 ounces. Shake thoroughly
and let stand for 24 hours. The sample shall then show a prac-
tically colorless solution, or at least, a solution not darker than
straw color.
(c) Fine aggregate shall be well graded from coarse to fine and
when tested by means of laboratory sieves, shall conform to the
following requirements:
Passing
3/8" sieve
No. 4 sieve
No. 16 sieve
No. 50 sieve
No. 100 sieve
•
•
Per cent
100
85 to 100
45 to 80
2 to 30
0 to
5
These percentages are suggested as limiting percentages but
they may be altered within these limits to suit local conditions.
Removed by decantation
Shale (removed by flotation test)
Coal
(d) Fine aggregate shall be of such quality that mortar com-
posed of one (1) part cement and three (3) parts fine aggregate
by weight when made into briquets or cylinders, shall show a ten-
sile or compressive strength at seven (7) and twenty-eight (28)
days at least equal to the strength of briquets or cylinders
similarly made and proportioned with Ottawa sand.
3. Coarse Aggregate. (a) The coarse aggregate shall consist.
of crushed stone, gravel, blast-furnace slag or other approved inert
material of similar characteristics or combinations thereof, having
hard, strong, durable pieces and free from adherent coatings. The
amount of deleterious substances shall not exceed the following
percentage by weight:
Per cent
1.5
1
1
Clay lumps
Soft fragments
Other local deleterious substances (such as alkali,
friable, thin, elongated, or laminated pieces)..
Total shale, coal, clay lumps and soft fragments . 5
0.5
1
(b) Coarse aggregate shall be well graded from one (1) inch
down, 90 to 100% passing sieve with one (1) inch square open-
ings, 25 to 60% passing sieve with one-half (2) inch square open-
ings and not more than 10% passing screen having over one-
quarter (4) inch square openings.
5
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(c) Blast-furnace slag that meets the grading requirements of C2
these specifications shall conform to the following minimum
weight requirements:
General concrete
Concrete subject to abrasion
..65 lb. per cu. ft.
.70 lb. per cu. ft.
4. Mixed Aggregate. (a) Bank-run or mixed aggregate shall be
composed of a combination of hard, strong, durable particles of
sand and gravel or other approved inert material of similar char-
acteristics or combinations thereof, containing not more than
5% total deleterious substances. The proportion of fine aggre-
gate to coarse aggregate by volume shall not be less than one to
one and three-quarters (1:134) nor more than one to one (1:1).
When the amount of fine aggregate in the coarse aggregate is out
of proportion, it shall be corrected by screening and remixing.
Ninety (90) to 100% bank-run or mixed aggregate shall pass
a sieve with one (1) inch square openings.
(b) Mixed aggregate prepared prior to properly supervised pro-
portioning shall not be used.
III. CONSTRUCTION
1. Proportioning. The concrete shall be mixed in the propor-
tions by volume of one (1) part Portland cement, two and one-
half (22) parts fine aggregate and four (4) parts coarse aggre-
gate. If bank-run or mixed aggregate is permitted by the architect
or engineer the proportions shall be one (1) part Portland cement
to six (6) parts bank-run or mixed aggregate. In either case, the
number of sacks of cement per cubic yard of concrete in place shall
not be less than five and one-half (5%).
2. Measuring. The method of measuring the materials for the
concrete or mortar, including water, shall be one which will insure
separate and uniform proportions of each of the materials at all
times. A sack of Portland cement (94 pounds net) shall be con-
sidered one (1) cu. ft.
3. Machine Mixing. All concrete shall be mixed by machine
on the job or at a central mixing plant except when the engineer
shall otherwise permit under special conditions. A batch mixer
of any approved type shall be used. The ingredients of the con-
crete or mortar shall be mixed to the specified consistency, and
the mixing shall continue for at least one (1) minute after all ma-
terials are in the drum. The drum shall be completely emptied
before receiving material for the succeeding batch.
4. Central Mixing Plants. (a) All concrete ingredients shall
comply in all respects with the requirements for materials specified
hereinbefore.
(b) Measurement. Cement shall be measured by weight or
in a full bag. When the cement is measured by weight, it shall
be weighed on a scale separate from those used for the other ma-
6
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
terials; when the cement is measured in bags, no fraction of C2
bags shall be used.
Coarse aggregates shall be measured by weight. Fine aggre-
gates shall be measured by weight or by inundated volume in a
device satisfactory to the engineer.
Water shall be measured by volume or by weight.
Powdered admixtures shall be measured by weight and liquid
admixtures by weight or volume.
(c) Mixing. The mixing equipment shall be capable of mix-
ing the aggregates, cement, and water within the specified time
into a thoroughly mixed and homogeneous mass which can be
discharged without segregation.
In the case of stationary mixers, the mixer drums shall be of
adequate size to accommodate the maximum batch, and shall
be in accordance with the Concrete Mixer Standards adopted
by the Mixer Manufacturers' Bureau of the Associated General
Contractors of America. The mixer drum shall be rotated at the
rate specified by its manufacturer.
When the central mixing plant is depended upon for the com-
plete mixing, the minimum mixing time for mixers of one cubic
yard capacity or less shall be one minute; for larger capacities
of mixers this mixing time shall be increased at the rate of one-
quarter (4) minute for each cubic yard or less additional
capacity. When the concrete is transported in an agitator truck
provided with mixing blades, the mixing time at the central
mixer may be reduced to the minimum required to incorporate
the ingredients of the mix into a mass and the mixing completed
in the agitator; under these circumstances each batch of
concrete shall be mixed in the agitator for fifty (50) revolutions
or more.
(d) Delivery. Concrete shall be delivered to the work at the
consistency specified, and shall be hauled in a water-tight con-
tainer in which segregation will not take place and from which
the concrete can be discharged freely.
Concrete shall be delivered to the site of the work and dis-
charge from the hauling container begun within a period of one
and one-half (12) hours after the introduction of the mixing
water to the dry materials.
Concrete delivered in out-door temperatures lower than 40° F.
shall arrive at the work having a temperature not less than
60° F., nor greater than 100° F., unless otherwise specified by
the engineer.
(e) Inspection. Proper facilities shall be provided for the engi-
neer to inspect and sample the concrete at the mixing plant, load-
ing plant and point of delivery.
5. Consistency. The materials shall be mixed wet enough to
produce a concrete of consistency that will flush readily under
slight tamping, but which can be handled without causing a sepa-
ration of the coarse aggregate from the mortar.
7
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
6. Hand Mixing. When it is necessary to mix by hand, the C2
material shall be mixed dry on a water-tight platform until the
mixture is of uniform color, the required amount of water added,
and the mixing continued until the mass is of proper consistency
and homogeneous.
7. Retempering. Retempering of mortar or concrete which has
partially hardened, that is, remixing with or without additional
materials or water, shall not be permitted.
8. Forms. The forms for concrete curb shall be made of sub-
stantial materials, preferably steel forms. They shall be braced or
staked so as to insure perfect alignment and grade. If the curb.
is precast, i. e., not molded in place, the forms, preferably steel,
shall be so constructed that they will permit uniform spacing and
finish as herein specified.
9. Finish. (a) Monolithic Finish. After concrete is poured into
the forms it shall be puddled and spaded so as to insure a thorough
mixture, eliminate air pockets, and create uniform and smooth
sides. Before the concrete has thoroughly set, and while the
concrete is still green, the forms shall be removed and the front
and top sides shall be finished with a float or steel trowel to make
a uniform finished surface.
(b) Mortar Finish. Immediately before pouring, the front form
for the curb shall be coated on the inside with approximately one-
quarter (1) inch of 1:2 mortar. The concrete shall be thoroughly
spaded and puddled in the forms. The top one-half (½) inch of
the forms shall be filled with 1:2 mortar. While the concrete is
still green, the forms shall be removed and the face and top of the
curb shall be troweled with a steel trowel to a smooth uniform
finished surface.
10. Rounding Corners. (a) Wherever corners are to be
rounded, special steel trowels shall be used while the concrete is
workable and the corners constructed to the dimensions herein
specified.
(b) For combined curb and gutter, the top and side of curb and
gutter may be finished by the use of a special-shaped trowel or
curb-and-gutter machine which will shape the entire upper sur-
faces in accordance with the dimensions and shape specified. This
trowel shall be used immediately upon removing the front form
of the curb and while the concrete is still workable but firm enough
to stand up.
11. Smoothness. The top and face of the curb and also the top
of the apron on combined curb and gutter must be finished true to
line and grade and without any irregularities of surface noticeable
to the eye. Should any portion of the gutter hold water to a depth
of more than one-fourth (4) of an inch, or should any portion of
the surface or face of the curb or gutter depart more than one-
fourth (14) of an inch from a straight edge ten (10) feet in length,
8
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
placed on the same parallel to the center line of the street, or should C2
any part of the exposed surfaces present a wavy appearance, the
same will be sufficient cause for rejection of that portion of the
work, and the engineer shall have the right to cause the work to
stop at any time, if the work being produced is not satisfactory to
him.
12. Treatment and Curing. As soon as the finished curb has
hardened sufficiently to prevent damage, the surface of the curb
shall be sprinkled with water or preferably covered with burlap
and, in either case, kept wet for at least three (3) days. When per-
mitted by the architect or engineer, a chemical curing agent may
be used, provided it is applied according to the manufacturer's
specifications. When desired by the architect or engineer, high
early strength or quick-setting cement may be used and the
curing period reduced to twenty-four (24) hours.
13. Protection. The freshly finished curb shall be protected
from hot sun and drying winds until it can be sprinkled and cov-
ered as above specified. The concrete surface must not be dam-
aged or pitted by rain drops, and the contractor shall provide and
use, when necessary, sufficient covering to completely protect all
sections that have been placed within the preceding twelve (12)
hours. The contractor shall erect and maintain suitable barriers
to protect the curb from traffic and any section damaged from
traffic or other causes, occurring prior to its official acceptance,
shall be repaired or replaced by the contractor at his own expense
in a manner satisfactory to the engineer. Before the street is
opened for traffic the covering shall be removed and disposed of
by the contractor. The street shall not be opened to traffic until
the engineer directs.
14. Temperature Below 35 Degrees Fahrenheit. If at any time
during the progress of the work the temperature is, or in the
opinion of the engineer will, within twenty-four (24) hours, drop
to 35° F., the water and aggregates shall be heated and precautions
taken to protect the work from freezing for at least five (5) days.
15. Joints. (a) All concrete curb shall be jointed or flagged
in sections approximately six (6) feet in length or as otherwise
directed by the architect or engineer. All markings shall be cut
through the finishing coat with proper marking tools. All joints
and outer edges shall be neatly rounded and finished with special
tools.
(b) All concrete curb not reinforced shall be cut clear through
by the use of steel templates three-sixteenths (3) inch in
thickness at approximately twelve (12) foot intervals.
(c) The use of steel templates may be eliminated in reinforced
concrete curbs.
16. Expansion Joints. One-half (2) inch expansion joints shall
be placed between sections of curb at intervals of fifty (50) feet
or opposite expansion joints in pavement. These joints shall be
9
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
filled with pre-molded bituminous material which will meet the C2
requirements for coal-tar-pitch filler or asphalt filler as specified
in A. P. W. A.-E1-36, Stone Block Pavements. When steel
templates are used to separate the curb, expansion joints may
be eliminated. At street intersections where straight curb meets
the curved section of curb either expansion joints or metal tem-
plates shall be used.
COMBINED CURB AND GUTTER
I. GENERAL
1. Dimensions. The cross-section of combined curb and gutter
shall be as shown in detail on the plans or as follows: Total width
of base twenty-four (24) inches, thickness of gutter slab eight
(8) inches, thickness of curb at top six (6) inches, thickness at
gutter seven (7) inches and height of curb above gutter six (6)
inches. It shall preferably be reinforced with three-eighths (3%)
inch round plain or de-formed bars. The front face of the curb
will have a batter of one (1) inch from bottom to top and the top
corner of curb face will be rounded to one (1) inch radius, while
the intersection of curb and gutter shall be rounded to one and
one-half (12) inch radius. The top of the gutter slab at the street
edge shall be five (5) inches below the top of the curb.
II. MATERIALS AND CONSTRUCTION
1. Requirements. Proportion, materials, forms, measurements,
mixing, consistency, finish, construction, protection, joints, ex-
pansion joints, etc., shall be in accordance with the specification
herein given for concrete curb.
PRE-MOLDED REINFORCED CONCRETE CURB
I. MANUFACTURE
1. Materials and Length. Reinforced concrete curb, pre-
molded, of the materials and dimensions shown on the plans, shall
be manufactured in standard lengths of six (6) feet by the method
hereinafter specified, or some method equally good.
2. Forms. (a) Collapsible forms shall be used which may be
designed to cast a series of units. Ends must be square with top
and sides.
(b) of the two faces which are to be exposed after laying, one
or both shall be cast against a steel form. If only one is cast
against a steel form the other shall be trowel-dressed.
3. Concrete for Curb. (a) The curb shall be made of Portland
cement concrete in the proportion of one (1) part to two (2) parts
fine aggregate to three (3) parts coarse aggregate. All ingredients
shall meet the specifications for materials hereinbefore specified.
The number of sacks of cement per cubic yard of concrete in place
shall not be less than six and one-half (6½).
10
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(b) The concrete shall be mixed in a machine mixer of approved
type for at least three (3) minutes after all ingredients have been
placed in the drum.
4. Consistency. Concrete shall be of such consistency that it
may be placed without excessive ramming, but the use of excess
water in order to secure a flowing concrete will not be permitted.
The consistency required is that generally described as creamy.
The amount of water to be used in mixing will be determined from
time to time by the engineer, and when once determined shall be
used for each batch until further notice. This uniformity shall be
secured by measuring the water in the water tank on the mixer,
which tank shall be equipped with a gage-glass graduated to gal-
lons and quarters.
5. Withdrawal of a Mixed Batch. Under no circumstances will
a mixed batch or any part thereof be removed from the drum dur-
ing the process of placing the succeeding batch in the drum.
6. Finish. The concrete shall be poured and manipulated in
such a manner that the top and face of the curb shall have plane
surfaces, showing no coarse aggregate or pockets. As the forms
are removed, and while the concrete is green, the top and ten (10)
inches of the face shall be rubbed down with a plane wood block.
7. Protection. While curing, the curb shall be protected from
direct rays of the sun and shall be kept moist for at least ten (10)
days before placing in curb trench.
8. Closures. Special: Cutting of concrete curbstones will in no
case be permitted. Short lengths for final closures, which are to
permit of special locations of drop curbs, shall be made to dimen-
sion for the particular purpose, either separately, as in the case of
standard lengths, or may be cast in place in the street after the
other curb has been set and concreted.
C2

11
}
PAT
DATE DUE


STANDARD SPECIFICATIONS
FOR PUBLIC WORKS CONSTRUCTION
Architecturaf
Libran
T
$
186
08
E-STONE BLOCK PAVEMENTS
E1-Stone Block Pavement
AMERICAN PUBLIC WORKS ASSOCIATION
CHICAGO, ILLINOIS
UNIVERSITY OF MICHIGAN LIBRARIES
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Can Be
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I. GENERAL
Specification for
STONE BLOCK PAVEMENT
This pavement shall consist of stone blocks and sand cushion, or
cement-sand bed paved on the previously constructed concrete base
course. The type of block and character of joint filler and material
for the cushion or bed shall be as designated in the proposal.
II. MATERIALS
1. New Granite Blocks. (a) Quality of Granite. The blocks
shall be of granite of medium-size grain, showing an even distribution
of constituent minerals. They shall be of uniform quality and texture
throughout, and free from seams or disintegrated materials.
-Class A-
French coefficient
A.P.W.A.—E1-36
The quality of granite shall conform to the requirements for Class A
or Class B for extra heavy or heavy traffic respectively, as designated
in the proposal:
Toughness
(Percentage of wear.
•
ARCHITECTURAL
LIBRARY
TE
180
·A58
•
·
Not less than 11
Not more than 3.6)
Not less than 9
-Class B-
French coefficient
(Percentage of wear.
Toughness
The average of three tests shall be used for determining both the
percentage of wear and toughness.
.Not less than 8
Not more than 5.0)
. Not less than 7
(b) Size and Dressing of Blocks. The blocks shall be of the follow-
ing dimensions: Not less than eight (8) nor more than twelve (12)
inches long on top; not less than four and three-quarters (4¾) nor
more than five and one-quarter (54) inches deep; and the width on
the top shall be either three and one-half (3%) to four and one-half
(42) inches, or four and one-half (42) to five and one-half
(52) inches.
The blocks shall be so dressed that the faces will be approximately
rectangular in shape, and the ends and sides sufficiently smooth to per-
mit the blocks to be laid with joints not exceeding one-half (2) inch
in width at the top, and for one (1) inch downward therefrom, and not
exceeding one (1) inch in width at any other part of the joint. The
top surface of the block shall be so cut that there will be no depressions
measuring more than three-eighths (3%) of an inch from a straight
E1
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
edge laid in any direction on the top and parallel to the general surface E1
thereof.
2. Resurfacing Blocks. (a) Size and Character. Resurfacing
blocks for use on old concrete foundations where less than the standard
depth of blocks must be used, shall be seven (7) to eleven (11) inches
long, three and one-half (32) to four and one-half (42) inches
wide and three and one-half (3½) to four (4) inches deep, and shall
in all other respects meet the requirements as to quality and dressing
for new granite paving blocks.
3. New Sandstone Blocks. (a) Quality, Size and Dressing. The
paving blocks shall be of sound, hard sandstone, free from clay, seams,
or defects which would injure them for paving purposes, of uniform
quality and texture.
They shall be quarried from fine-grained live rock, showing a
straight and even fracture, and shall be made by splitting and break-
ing from large quarried blocks and not by redressing old paving
blocks.
The blocks shall be of the following dimensions: Not less than eight
(8) nor more than ten (10) inches long; not less than three and one-
half (3½) nor more than five (5) inches wide on top; not less than
five (5) nor more than five and one-half (52) inches deep.
These blocks shall conform in character of dressing to the require-
ments for granite blocks in Section 1, (b).
4. Durax Paving Blocks. (a) Quality, Size and Dressing. Durax
paving blocks shall be cut from granite complying with the require-
ments specified herein for new granite paving blocks.
The blocks shall be cubes of granite with six (6) approximately
square surfaces, the edges of which measure not more than four (4)
nor less than three (3) inches in length. They shall be dressed so as
to conform with the requirements specified for new granite blocks
except as to form and dimensions.
(b) Method of Paving. They shall be laid as specified for new
granite blocks except that the courses shall be laid in circular con-
centric arcs with the largest blocks at the center of the arc and the
smaller ones at the springing line. The radii of the arcs may be varied
from three (3) to seven (7) feet.
5. Sampling and Inspection of Blocks. (a) Preliminary Samples
and Certificates. Contractors shall file with the engineer, at or before
the time of bidding, a certificate showing the name and location of the
quarry or quarries from which it is proposed to obtain the blocks, to-
gether, in the case of granite blocks, with a copy of a report or reports
from an approved laboratory showing results of tests for toughness
and per cent of wear. The contractor shall further file with the
engineer, prior to the letting, six (6) specification blocks representing
the stone proposed for use, except that such samples will not be re-
quired where a previous sample of the same blocks has been filed and
approved.
2
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
(b) Sampling and Inspection of Shipments. Samples selected from E1
shipments for physical tests by the engineer or his representative shall
consist of not less than six (6) blocks so chosen as to fairly represent
actual deliveries. No samples shall include blocks that would be re-
jected by a visual examination and the bedding plane shall be marked
on at least two of the blocks selected.
All deliveries shall be subjected to further inspection at the place
of use prior to and during laying, and blocks which fail to conform
to the requirements of these specifications shall be rejected.
6. Materials for Cement-Sand Bed. Cement-sand bed shall con-
sist of one part Portland cement and four parts by volume of clean,
coarse sand, well-graded from a maximum size of one-quarter (4)
inch particles.
7. Materials for Grout Filler. Grout joint filler shall consist of
one part Portland cement and one part by volume of clean, sharp, well-
graded, fine sand, free from particles of such size as to obstruct the
ready flow of the grout to the bottom of the joints.
8. Materials for Bituminous Mastic Filler. Bituminous mastic
filler shall consist of a combination of approximately equal parts by
volume of sand or mineral matter as specified below with one of the
bituminous materials hereinafter specified. The engineer shall desig-
nate in each case which filler shall be used.
(a) Sand. Sand for bituminous mastic filler shall consist of clean,
durable grains of which all shall pass a standard 10-mesh sieve and
85% by weight shall pass a 20-mesh sieve.
(b) Mineral Matter. Mineral matter shall consist of naturally con-
tained colloidal matter or ground or pulverized slate, limestone or dolo-
mite, at least 99% of which shall pass a 200-mesh sieve and 95%
shall pass a 300-mesh sieve. This mineral matter shall be mixed with
the asphalt cement specified in (d) to obtain a proportion of not less.
than 35% or more than 55% by weight of the total mixture.
(c) Tar Pitch Filler. The coal-tar pitch shall conform to the fol-
lowing requirements; tests to be made on the sample as received, but
results reported on a dry basis. The softening point shall have a range
of not more than 10° F. within the limits below given, as may be
directed.
Water
.0.00 per cent
Softening point (Cube-in-Water Method). 46 to 57° C.
(115 to 135° F.)
Distillation test:
Total Distillate, by weight, 0 to 300° C. (32 to 572° F.)
not more than 10 per cent
not less than 90 per cent.
Residue, by weight..
Specific gravity at 25°/25° C. (77°/77° F.) of total distillate
to 300° C. (572° F.)
. not less than 1.03
Softening point (Cube-in-Water Method) of residue from
distillation test
not more than 75° C. (167° F.)
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
Ductility at 50 to 100 penetration, at 25° C. (77° F.)
not less than 50 cm.
Note. The penetration of the pitch shall be brought within the range of
50 to 100 penetration by heating in an open vessel with frequent stirrings at
a temperature of not over 350° F.
Total Bitumen (Soluble in Carbon Disulphide)
(d) Asphalt Cement Filler.
geneous and free from water.
quirements:
65 to 80 per cent
The asphalt cement shall be homo-
It shall conform to the following re-
Penetration at 25° C. (77°
Flash point (open cup)
Loss on heating at 163° C.
F.), 100 g., 5 sec. .60 to 70
not less than 175° C. (347° F.)
(325° F.), 50 g., 5 hr.
not more than 2 per cent
Penetration at 25° C. (77° F.), 100 g., 5 sec. of residue
after heating at 163° C. (325° F.) as compared with
penetration of asphalt cement before heating
not less than 60 per cent
. not less than 30 cm.
Ductility at 25° C. (77° F.).
Proportion of bitumen soluble in carbon tetrachloride
not less than 99 per cent
(e) Tar and Asphalt Filler. This material for use in bituminous
mastic filler shall be a mixture of coal tar pitch and refined asphalt,
consisting of 100 parts of coal tar and 20 parts of refined asphalt.
These products shall comply respectively with the requirements of
paragraphs (c) and (d), except that the penetration of the asphalt
at 77° F. shall be not less than 30 nor more than 40.
III. CONSTRUCTION
1. Care in Handling Blocks. Care shall be exercised in handling
the blocks so that the edges and corners shall not be chipped or broken,
as blocks otherwise acceptable may be rejected on account of spalling.
2. Sorting Blocks. The blocks shall be sorted and laid in courses
of uniform width, except in special cases, as may be ordered. The
stone from each quarry shall be piled and laid separately in different
sections of the work, and in no case shall the stones from different
quarries be mixed.
3. Cushion or Bed. On the previously constructed concrete base.
course shall be spread a layer averaging one (1) inch in depth of sand
cushion or of a mixture of one (1) part cement and four (4) parts sand
for cement-sand bed as designated in the proposal.
4. Laying the Pavement. Upon the sand cushion or cement-sand
bed the blocks shall be laid in courses at right angles to the line of
the street, and in a straight line from curb to curb, except in special
cases, when they shall be laid at such an angle as may be directed by
the engineer. The blocks shall be laid as closely as possible, each block
touching the adjoining one on sides and ends, and in courses of uni-
E1
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
form width. All joints shall be broken with a lap of at least E1
three (3) inches. The blocks shall not be laid more than twenty-five
(25) feet in advance of the ramming. After the blocks are laid, they
shall be rammed to a solid bearing, the joints shall be adjusted, all un-
satisfactory blocks shall be taken out with tongs and all low blocks
shall be raised to an even and true surface. Pinch bars shall not be used
except by special permission of the engineer and no sand shall be
placed in the joint except when mixed with the filler specified in the
proposal.
5. Applying Bituminous Mastic Filler. Bituminous mastic joint.
filler shall consist of bituminous material complying with one of the
sets of requirements in Section II, 8, unless otherwise indicated in the
proposal, thoroughly mixed with as much hot, dry sand as the bi-
tuminous material will carry, but in no case shall the volume of sand
exceed that of the bitumen nor be less than 40% of the bitumen. The
sand shall be heated to a temperature of not less than 300° F., nor
more than 400° F., and shall be between these limits when mixed with
tar or asphalt. The bituminous material shall be heated in kettles,
equipped with approved thermometers. Tar filler at the time of use
shall have a temperature of 250° to 325° F., and asphaltic cement shall
be used at a temperature of 275° to 350° F.
The mixture shall be flushed on the surface of the blocks and pushed
into the joints with suitable tools, reflushed or repoured if necessary,
until the joints remaining are permanently filled, flush with the surface
of the pavement. As little as possible of the mixture shall be left
on the surface.
In applying the filler, care shall be taken that the pavers are closely
followed by the filler gang, and in no case shall the paving be left over
night, or when work is stopped, without the filling of the joints being
completed. In case rain stops the filler gang before its work is finished,
the joints shall be protected by the use of tarpaulins, or other means to
keep out water. Under no circumstances shall the filler be poured into
wet joints.
6. Portland Cement Grout Filler. Portland cement grout filler
shall consist of one part Portland cement and one part of clean, sharp
sand as hereinbefore specified. The cement and sand shall be
thoroughly mixed in a batch mixer of approved type using only enough
fresh water to make a grout which will flow to the bottom of the joints
and shall be applied to the joints before the ingredients have separated.
Prior to grouting, the pavement shall have been brought to a uniform
surface and the blocks shall be wetted. The grout shall be broomed or
scraped into the joints if necessary to fill same and the operation shall
be repeated as the grout settles and before the initial set has taken place.
until the joints are thoroughly filled, flush with the surface of the
blocks. Immediately after this, the entire pavement shall be broomed
to a smooth surface.
7. Protection of Surface. After the grouting is completed and
a sufficient time for hardening has elapsed so that a coating of sand will
5
运
​AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1936)
not absorb moisture from the cement mixture, one-half (½) inch of El
sand shall be spread over the whole surface and shall be kept damp
until the street is opened for traffic.
After the grouting is completed the street shall be kept closed and no
carting or traffic allowed on any part of the grouted pavement until at
least seven (7) days have elapsed.
Should the bond between the blocks become broken before the work
is accepted, such defective work shall be regrouted or relaid and again
protected as previously described.
NOTES REGARDING THE FOREGOING SPECIFICATION FOR
STONE BLOCK PAVEMENTS
1. Modifications. These specifications are so drawn as to include
all well-known forms of stone block paving, covering size, form, and
quality of block and character of cushion and joint filler. Since all
of these variations would not be acceptable on any one project, the
specifications for use in any given case must either be modified by
eliminating materials which are not acceptable, or must be accom-
panied by a proposal clearly indicating the exact character of paving
required.
2. Use of Recut or Redressed Paving Blocks. Specifications for
recut or redressed paving blocks may be formulated along lines par-
allel to those for new paving blocks. It is recommended that old
blocks cut from stone complying with the requirements of these spec-
ifications as to quality shall be employed for this purpose. Require-
ments for dressing should be the same as those for new blocks, but the
dimensions must be varied in accordance with the dimensions of the
old blocks to be redressed.
6
}
:
DATE DUE

STANDARD SPECIFICATIONS
FOR PUBLIC WORKS CONSTRUCTION
Gratis aber
Aihery
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F-PORTLAND CEMENT CONCRETE
PAVEMENTS
F1-Portland Cement Concrete Pavement
AMERICAN PUBLIC WORKS ASSOCIATION
CHICAGO, ILLINOIS
Pagg. Mal
UNIVERSITY OF MICHIGAN LIBRARIES
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
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offer and get a
F1
Specification for
PORTLAND CEMENT CONCRETE PAVEMENT ARCHITECTURAL
LIBRARY
A.P.W.A.-F1-44
INTRODUCTION
These specifications are intended to cover average conditions for
concrete and reinforced concrete pavements. Throughout the speci-
fications certain minimum requirements, which have been known to
give satisfactory results for average conditions, are given. For other
conditions of traffic and for unusual conditions of subgrade and
drainage it will be necessary for the engineer to make special pro-
visions such as providing for subgrade treatment, additional strength
in the pavement slab, etc.
I. SUBGRADE
See Specification for Earth Subgrade, A.P.W.A.—B1.*
II. MATERIALS
1. Cement. Standard Specifications for Portland Cement,
A.S.T.M. Designation: C150 are adopted as part of these specifications.
Unless otherwise specified, portland cement shall conform to the re-
quirements of A.S.T.M. Designation: C150 for Type I Cement. High-
early-strength portland cement shall conform to the requirements of
A.S.T.M. Designation: C150 for Type III Cement. White or very
light colored cement shall conform to the requirements of A.S.T.M.
Designation: C150 for Type I Cement as to quality, but the color of
these cements shall be approved by the Engineer in each case.
The use of Vinsol resin, Darex, or other air entraining ingredients.
is recommended where sodium chloride or calcium chloride is used for
snow and ice removal. Cement containing these ingredients shall con-
form to the Tentative Specifications for Air-Entraining Portland
Cement for Concrete Pavements, A.S.T.M. Designation: C175T
(Type IA).
2. Concrete Aggregates: Standard Specifications for Concrete
Aggregates, A.S.T.M. Designation: C33 are adopted as part of these
specifications for both fine and coarse aggregate.
Coarse aggregate shall be uniformly graded within the limits shown
in Table I and and any material which does not come within the limits
specified shall be used only upon written order of the Engineer.
At least two separate sizes of coarse aggregate shall be used to
insure uniformity. The separate sizes shall be proportioned so that
* See Appendix I, Recommendations on Design.
TE
18
A 58
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
the resulting coarse aggregate mixture shall be graded uniformly and F1
come within the limits of the grading specified in Table I, for the
designated sizes of coarse aggregate specified. The smaller size ag-
gregates shall have 95 to 100% passing a sieve of one inch for the 2
inch coarse aggregate mixture and of three-quarter inch for the 1½
inch coarse aggregate mixture.
TABLE I. GRADING OF COARSE AGGREGATE
Percentage by weight passing
Standard Square Mesh Sieve
Sieve
Size
2½"
2"
1½″
1"
3/4″
1½"
3/8″
#4
Aggregate
Designated
2" to #4
100
95-100
35-70
10-30
0-5
Aggregate
Designated
1½" to #4
100
95-100
35-70
10-30
0-5
Coarse aggregate, except air-cooled blast furnace slag, shall show
not more than 50 per cent loss by the Standard Method of Test for
Abrasion of Coarse Aggregate by use of the Los Angeles Machine,
A.S.T.M. Designation: C131. A loss of not more than 32 per cent is
desirable.
(a) Soundness Test. Any coarse aggregate which shows a
weighted average loss of more than 10 per cent after five cycles of the
sodium sulphate soundness test (A.S.T.M. Designation: C88) shall
be rejected. A coarse aggregate failing to meet the above requirements
may, at the option of the Engineer, be used if it has proven to be sound
and satisfactory by long service in concrete of comparable proportions
that has been exposed to natural weathering.
(b) Air-cooled blast furnace slag shall consist of roughly cubical
fragments reasonably uniform in density and quality, reasonably free
from metallic iron, and containing no dirt or other objectionable matter.
The slag shall weigh not less than 70 pounds per cubic foot, using the
Standard Method of Test for Unit Weight of Aggregates, A.S.Ť.M.
Designation: C29.
3. Water. Water for concrete shall be clean and free from in-
jurious amounts of oils, acids, alkalies, organic matter, or other
deleterious substances. Test specimens of mortar made from the
materials used in the work or from standard Ottawa sand and the
water to be used in the work shall develop a tensile or compressive
strength at 7 days not less than 95 per cent of that developed by
specimens of the same materials and proportions, and distilled water.
2
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
4. Reinforcement. Reinforcing material shall be either cold-drawn F1
steel wire fabric, or steel bars.
(a) Wire Fabric. Wire fabric shall consist of sheets or strips
manufactured for the purpose. The finished material shall comply
with the Standard Specifications for Welded Steel Wire Fabric for
Concrete Reinforcement, A.S.T.M. Designation: A185.
Unless otherwise shown on plans, parallel members of the fabric
shall be spaced not less than four (4) nor more than twelve (12)
inches. No member shall have an effective area of less than twenty-
eight thousandths (0.028) of a square inch. All adjacent fabric sheets
shall be lapped by an amount equal to forty (40) times the diameter
of the largest member being lapped, if end cross wires do not overlap ;
or by an amount which will permit end cross members of each sheet to
overlap each other by at least one (1) inch. The same requirements
apply to end laps and side laps of sheets.
(b) Bars. Plain or deformed bars shall be made by either the
Bessemer or the open-hearth process. Rolled rail steel will be accepted,
except for tie bars that are to be bent and restraightened during
construction. The bars shall conform to the requirements of the
Standard Specifications for Billet-Steel Bars for Concrete Reinforce-
ment, A.S.T.M. Designation: A15 or to the Standard Specifications.
for Rail-Steel Bars for Concrete Reinforcement, A.S.T.M. Designa-
tion: A16. Bars depending upon bond for their effectiveness shall be
free from excess rust, scale or other substance which prevents the
bonding of the concrete to the reinforcement.
(c) Bar Mats. Bar mats shall conform to the requirements of the
Standard Specifications for Fabricated Steel Bar or Rod Mats for Con-
crete Reinforcement, A.S.T.M. Designation: A184. No member
shall have an effective cross-sectional area of less than forty-nine
thousandths (0.049) of a square inch. Unless otherwise shown on
plans, members shall be spaced not more than eighteen (18) inches
apart in either direction. Where continuity of reinforcement is re-
quired, plain bars shall be lapped not less than forty (40) times their
diameter; deformed bars not less than thirty (30) times their diameter.
Where bars are fabricated by positive welding at all joints, the lap
may be only of such length as will permit end cross bars to overlap
each other by at least two (2) inches. The same requirements apply
to end laps and side laps. All intersections of longitudinal and trans-
verse bars shall be securely wired or clipped or welded together so
as to resist displacement during the concreting operations.
(d) The width and length of fabric sheets or bar mats shall be such
that, when properly placed in the work, the extreme longitudinal and
transverse members will be located approximately three (3) inches
from the edges of the slab, unless otherwise shown on the plans.
(e) Dowel and Tie Bars. Deformed steel bars meeting the speci-
fications for bar reinforcement shall be used for the tie bars joining
slabs together across longitudinal hinged joints or joining slabs to
curb or to gutters. Dowels across expansion joints, when specified,
shall be smooth, round bars. Dowel and tie bars shall be of the design
3
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
and placed as shown on the plans. Dowels shall be held in position F1
exactly parallel to surface and center line of the slab, by a metal
device that is left in the pavement. This device shall hold each dowel
in exactly the correct position, so firmly that the dowel's position
cannot be altered by concreting operations. Bond between concrete
and dowels shall be prevented in one slab. The unbonded half of each
dowel bar shall be coated with a film of heavy grease. The unbonded half
of each bar shall be provided with a close-fitting, closed-end metal
sleeve, not more than 6 inches long, with suitable flange to hold the
end of the sleeve from the end of the bar, so that a space of not less
than the proposed thickness of the joint will be provided between the
end of bar and sleeve at the greased end of the bar.
(f) Deformed Metal Joint. Sheets for tongue and groove longi-
tudinal joints or transverse contraction joints shall consist of steel or
iron not thinner than 18 gauge U. S. Standard. Each section shall be a
continuous strip of metal not more than fifteen (15) feet in length and
having a width one-half (2) inch less than the depth of the pavement.
It shall be of the cross-section shown on the plans and be provided with
an end connection which will hold the ends of strips firmly together.
It shall be punched for dowels, or tie bars, and pins, as shown on
the plans.
Channel shaped pins pressed out of sheet steel of not less than
16 gauge U. S. standard and not less than 11 inches long shall be used
to hold the joint metal upright on the subgrade.
5. Joint Fillers. (a) Bituminous Premoulded Fiber Joint
Filler. This material shall conform to the requirements of the tentative
revision of the Standard Specifications for Preformed Expansion Joint
Filler for Concrete (Type V, Bituminous Fiber), A.S.T.M. Designa-
tion: D544.
(b) Poured Joint Filler. The material for filling poured joints and
for sealing cracks shall be bituminous fillers prepared from asphalt
meeting the following requirements:
The Asphalt Filler (Blown Type) for concrete pavements shall
conform to the following requirements:
The asphalt filler shall be homogeneous, free from water, and shall
not foam when heated to 200° C. (392° F.)
Flash Point (open cup), not less than 200° C. (392° F.)
Softening Point (ring and ball), 60° C. (140° F.) to 75° C. (167° F.)
Penetration at 0° C. (32° F.) 200 g., 1 min., not less than 20; at
25° C. (77° F.) 100 g., 5 sec., 50 to 60; at 46° C. (115° F.) 50 g.,
5 sec., not more than 160.
Loss on heating at 163° C. (325° F.) 50 g., 5 hrs., not more than
1.0 per cent. Penetration at 25° C. (77° F.) 100 g., 5 sec. of residue
after heating at 163° C. (325° F.) as per cent of original penetra-
tion of asphalt filler before heating, not less than 50 per cent.
Ductility at 25° C. (77° F.), 10 cm. to 30 cm.
4
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
Total Bitumen (soluble in carbon disulphide), not less than 99.0 F1
per cent.
Proportion of bitumen soluble in carbon tetrachloride, not less than
99.0 per cent.
Poured joint filler is to be heated, as required for placing in joints,
but not in excess of 375° F.
(c) Preformed Cork Joint Filler. This material shall conform to
the requirements of the Standard Specifications for Preformed Expan-
sion Joint Filler for Concrete (Type I, Cork), A.S.T.M. Designation:
D544.
(d) Preformed Self Expanding Cork Joint Filler. This material
shall conform to the requirements of Standard Specifications for Pre-
formed Expansion Joint Filler for Concrete (Type II, Self Expanding
Cork), A.S.T.M. Designation: D544.
(e) Preformed Sponge Rubber Joint Filler. This material shall
conform to the requirements of the Standard Specifications for Pre-
formed Expansion Joint Filler (Type III, Sponge Rubber), A.S.T.M.
Designation: D544.
(f) Preformed Cork-Rubber Joint Filler. This material shall con-
form to the requirements of the Standard Specifications for Preformed
Expansion Joint Filler (Type IV, Cork-Rubber), A.S.T.M. Designa-
tion: D544.
(g) Redwood or Cypress Joint Filler. The filler shall be selected
from sound, clear, all heart, low density redwood or sound clear heart-
wood cypress, free from sapwood, knots, cluster birdseye, hard streaks,
shakes, splits, and shall comply with the following requirements:
(1) Dimensions shall be as specified on the plans, and tolerances
of +16 inch thickness, +% inch depth, and +4 inch length will be
permitted.
(2) A sample immersed in water for 24 hours immediately pre-
ceding the test shall be given three applications of a load sufficient
to compress the material to 50 per cent of its thickness before test.
The load shall be immediately released after each application. One
hour after the third application, the joint material shall have re-
covered to at least 70 per cent of its thickness before test.
The load required to compress the sample to 50 per cent of its thick-
ness before test shall not be greater than 1200 pounds per square inch.
6. Methods of Testing. Unless otherwise specified, all tests shall
be conducted in accordance with the latest Standards or Tentative
Standards of the American Society for Testing Materials.
III. PAVEMENT SECTION
1. Width, thickness and crown of the pavement shall be as shown
on the plans for the improvement.
IV. JOINTS
1. Joints. Joints shall be used where shown on the plans. The
plane of all joints shall make a right angle with the surface of the
pavement.
5
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I
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
2. Slab-Edge Rounding. The edges of the slab at all joints shall be F1
rounded with an edger having a radius of one-quarter (4) inch. The
edging shall be done symmetrically on each slab with the plane of the
joint, and so that the edge of one slab will not ride the other, thus avoid-
ing spalling of the edges.
3. Compacting at Joints. The concrete along the face of all joints,
except dummy joints formed after the concrete surface is completed,
shall be compacted with a vibrator inserted in the concrete and worked
along the entire length of the joint to insure a surface which is free
from honeycomb.
4. Transverse Joints. Transverse joints shall be expansion, con-
traction or construction joints. They shall make a right angle with the
surface and with the center line of the pavement and extend through all
integral curb and in line across adjoining pavement slabs for the full
width of the pavement.
5. Expansion Joints. (a) Expansion joints shall extend entirely
through the depth and width of the pavement. They shall be of the
design, width and spacing shown on the plans.
(b) An expansion joint shall separate all pavement slabs from the
pavement in the street railway track area, other pavements and from
any rigid structures such as manholes, poles, etc., coming within the
area of the pavement.
I
(c) Premoulded and Preformed Expansion Joints. When the ex-
pansion joint is to be of the premoulded filler type, the filler shall be held
in place during the placing and finishing of the concrete by a metal bulk-
head, so that the top edge of the filler, unless otherwise shown on the
plans, shall be one-half (2) inch below the finished surface of the pave-
ment. The metal bulkhead shall be a steel plate at least 8 inch thick,
shaped to the exact cross-section of the pavement and having welded or
securely riveted to its upper edge an envelope which will enclose the top 2
inches of the expansion material and act as a lateral stiffener. The bulk-
head shall be securely staked in place perpendicular to both the center
line and subgrade of the pavement, with sufficient stakes to hold it in the
specified position and when so staked shall have sufficient strength to re-
main straight from edge to edge of slab when concrete is placed against
it. Concrete shall be deposited on both sides of the joint, and be struck
off before the bulkhead is removed.
-
Under no circumstances shall any concrete be left above the expan-
sion material or across the joint at any point. Any concrete spanning
the ends of the joints shall be cut away after the forms are removed.
Premoulded expansion joints shall be neatly filled to the surface of
the pavement with bituminous poured joint filler, without additional
compensation to the contractor.
(d) Poured Expansion Joint. When the expansion joint is to be
the poured type it shall be formed by securely staking a bulkhead in
place at right angles to the center line and surface of the pavement.
The bulkhead may be one or more wood or metal strips cut to the exact
cross-section of the pavement and having a total width equal to the
6
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
width of the expansion joint shown on the plans, and a depth of ½ inch F1
less than the depth of the pavement. Concrete shall be deposited on
both sides of the bulkhead and shall be compacted by an internal vi-
brator.
Before the pavement is opened to traffic, the joint shall be cleaned
so that there is a clear space of the specified width for the full depth
and width of the pavement. It shall then be neatly filled with bitumi-
nous joint filler which shall come flush with the surface of the pave-
ment. Any bituminous material on the surface of the pavement,
adjacent to the joint, shall be immediately scraped off.
6. Transverse Contraction Joints. (a) Contraction joints shall
be spaced as indicated on the plans. They shall be made by forming a
slot in the upper surface of the slab.
(b) The deformed metal plate joint shall be formed by staking the
specified metal key plate securely in place at right angles to the surface
and center line of the pavement. The plate shall be temporarily capped
with a metal channel cap made of ten (10) gauge sheet steel, having legs
at least one (1) inch long and a space between the legs one-eighth
(%) inch wider than the width of the deformed plate. Concrete shall
be deposited on both sides of the deformed plate and be carefully
spaded on each face of the plate. After the concrete has been placed
and finished, the metal cap shall be removed, leaving a groove in the
concrete from the top of the plate to the surface of the pavement.
The groove shall be neatly filled with bituminous joint filler before the
pavement is opened to traffic.
(c) Dummy contraction joint shall be constructed by forming in
the surface of the slab, a slot not less than 8 inch wide and having a
depth from one-third to one-half the depth of the pavement
at the thinnest part in its section. This slot may be formed in any
manner approved by the Engineer, such as by pushing into the concrete
a flat bar or the web of a "T" bar, removing the bar, and keeping the
slot open. Or it may be formed by setting a flat bar on chairs on the
subgrade and casting concrete about it, later removing the bar but
leaving the chairs in the pavement. If the bar is set in place ahead
of the concrete the concrete shall be carefully spaded along each face
of the bar.
When the bar forming the slot is removed before finishing of the
pavement surface is completed, the slot shall immediately be filled with
a strip of premoulded expansion material having a thickness and
depth equal to the width and depth of the slot. When the bar is not
removed from the pavement until finishing is completed, the slot shall
be filled with poured joint filler.
7. Transverse Construction Joints. (a) Whenever the placing
of concrete is suspended for thirty (30) minutes or more, a transverse
expansion or construction joint shall be constructed. Any concrete in
excess of that needed to form the joint shall not be used in the pave-
ment. However, such construction joints shall not eliminate the plac-
ing of expansion or contraction joints at the locations required by the
plans and specifications.
7
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
(b) When the joint at which work is suspended is not at the proper F1
location for a joint as shown on the plans or specified, a construction
joint shall be formed by securely staking in place at right angles to the
subgrade and center line of the pavement, a bulkhead of wood or metal
cut to the cross-section of the pavement and depositing concrete against
it. Before work is resumed the bulkhead shall be removed and the new
concrete placed against the face of the set concrete. In case deformed
metal transverse contraction joints are specified, they shall be placed
between the bulkhead and the concrete and left in place. Where the
slab reinforcement is not carried continuously across the construction
joint, tie bars as specified hereafter in paragraph 8, (e) shall be installed
across the joint.
(c) If concreting is stopped within five (5) feet of a previously
made transverse joint, the concrete shall be removed to this joint, with-
out additional compensation to the contractor for removing and re-
placing such concrete.
8. Longitudinal Joints. (a) Longitudinal joints shall be placed as
shown on the plans for the improvement. They shall be of the hinged
contraction or expansion type, as shown on the plans and hereinafter
described.
(b) Longitudinal Expansion Joints. Longitudinal expansion
joints shall be formed by placing a strip of premoulded joint filler
against the form, bulkhead, curb, pavement edge or adjacent structure.
It shall be held in this position by pins and concrete shall be placed
against it. The joint may be formed by constructing a slot in the con-
crete to the full depth of the pavement, of the width specified or shown
on the plans, and filling this slot with bituminous joint filler. Pre-
moulded or poured longitudinal expansion joints shall be constructed
and sealed as described for this type of transverse expansion joint.
(c) Longitudinal Hinged Joints. Longitudinal hinged joints shall
be of the deformed metal plate, keyed butt, or dummy joint type. The
deformed metal key plate joint shall be constructed by concreting in
place the specified deformed key plate parallel to the center line and
at right angles to the surface. Deformed metal plate or dummy hinged
longitudinal joints shall be constructed as described for these types of
transverse contraction joints. Pins shall be driven through the pin
holes in the metal plate at three and one-half (3½) foot intervals and
into the subgrade to hold the plate firmly in place as concrete is placed
about it. The exact location of all joints shall be determined by meas-
urement from the edge of the slab and none shall show an error in align-
ment of more than one-half (½) inch in fifty (50) feet.
(d) Longitudinal contraction or shrinkage joints shall be formed
with a keyed edge.
(e) Slabs shall be held together across longitudinal hinged joints by
tie bars of the dimensions shown on the plans. Tie bars shall bond with
the concrete on both sides of the joint. Tie bars or dowel bars shall
not be used across longitudinal expansion joints.
8
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
V. FORMS
1. Metal Forms. Metal forms shall be of shaped steel sections.
The sections shall have a length of at least ten (10) feet, except on
curves of less than one hundred and fifty (150) foot radius, where
shorter sections may be used. Metal forms shall have a depth equal to
the thickness of the concrete to be placed against them. They shall not
deflect more than one quarter (4) inch when tested as a simple beam
with a span of ten feet and a load equal to that which the finish or sub-
grading apparatus will put upon them. The use of bent, twisted or
worn out forms will not be allowed.
Forms eight inches or more in height shall be eight inches wide at the
base; forms less than eight inches in height shall have a base width of
not less than six inches.
At least three (3) stake pockets for bracing pins or stakes shall be
provided for each ten (10) feet of form and the bracing and support
must be ample to prevent the springing of the forms under the pressure
of the concrete or the weight or thrust of machinery operating on the
forms.
2. Wood Forms. Where hand finishing is used, wood forms shall
be not less than 2 inches thick (commercial dimension). Where
machine finishing is used, wood forms shall be not less than 3 inches
thick. The forms shall be dressed on one side, shall be equal in depth
to the thickness of the pavement at the edges, and on tangents shall
be not less than 10 feet long. Forms shall be held by stakes set at
intervals of not more than six (6) feet, two (2) stakes being placed at
each joint. The forms shall be firmly nailed to the side stakes, and
firmly braced at any point where necessary so that no movement will
result from the pressure of the concrete or the operation of the screed
or finishing machine.
When necessary to insure rigid forms and headers, the Engineer may
require that they shall rest on 2 inch x 2 inch hubs of sufficient length to
give a solid foundation to the forms, such hubs being spaced not over
four feet apart with one hub supporting each end of the form or header.
3. Setting. Forms shall be set upon the compacted subgrade and
to exact grade and alignment, for a distance of at least three hundred
(300) feet in advance of the placing of the concrete. Forms shall be
thoroughly cleaned and oiled before concrete is placed against them.
After setting, the top of forms shall be checked with a ten (10) foot
straightedge and any variation from that straightedge in excess of
one-eighth (%) inch shall be corrected.
4. Particular attention shall be given to the setting of the forms and
forming of the slabs at the outer edges to insure adequate drainage
and freedom from depressions which may hold water.
5. Forms shall be left in place until the concrete they enclose is at
least fifteen (15) hours old, and of sufficient strength. The method of
removing forms shall be such as will not damage the concrete.
F1
9
1
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
VI. WATER SUPPLY
1. Equipment. Where necessary the contractor shall provide suffi-
cient pumps and pipe line to assure an adequate supply of water for all
paving operations. The pipe line must be fitted with drains at the low
points, and air relief valves at the high points, and with convenient
outlets for all paving operations.
2. Water from City Mains. Water taken from the city mains shall
be paid for by the contractor at the rate of per thousand gallons.
3. Priority to Water Supply. The concrete pavement in place,
for ten (10) days after laying, and the subgrade preparations, shall
have prior rights to the water supply. If it should develop there is not
sufficient water for all purposes, the concrete mixer shall be shut down
until the water needs of the curing and subgrading operations have been
cared for.
VII. CURB AND GUTTER
1. Curb, curb and gutter, or gutter, when built in place, shall be
tied to the concrete pavement as shown on the plans.*
Transverse joints in the slab shall be continuous through curb,
gutter, or curb and gutter when the latter are cast in place.
2. Integral Curb. Where the plans call for an integral curb it shall
be constructed along the edge of the pavement as an integral part of the
slab and of the same concrete as the slab. The concrete for the curb
shall be deposited not more than 30 minutes after the concrete in the
slab.
VIII. PROPORTIONING CONCRETE
1. Measuring Materials. (a) The fine aggregate and each re-
quired "separated size" of coarse aggregate shall be separately weighed
into the hoppers in the respective amounts set by the Engineer.
Cement shall be measured by the bag as packed by the manufacturer
or by weight. In the latter case special scales and hopper shall be used
for the cement, with a device to indicate positively the complete dis-
charge of the batch of cement into the batch box or container. Ninety-
four pounds of bulk cement shall be considered one bag. Batches
involving fractional bags will not be allowed, unless the fractional
portion is weighed. Water shall be measured by volume or by weight.
(b) Unless otherwise permitted by the Engineer the batching plant
shall include batcher bins, either of the stationary or mobile type, with
adequate separate compartments for fine aggregate and for each re-
quired "separated size" of coarse aggregate, each compartment designed
to discharge efficiently and freely into the weighing hopper or hoppers.
Means of control shall be provided in each case so that as the quantity
desired in the weighing hopper is being approached, the material may be
added slowly in minute quantities and shut off with precision. Means
of removing the overload of any one of the several materials shall be
* See Appendix I.
F1
10
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
provided. In the type where more than one aggregate is weighed into F1
one hopper each aggregate shall be held in a separate compartment,
so arranged that an overload of any aggregate can be removed. Hop-
pers shall be constructed so as to eliminate accumulations of tare ma-
terials and to fully discharge without jarring the scales. Partitions
between compartments, both in bins and in hoppers, shall be ample to
prevent spilling under any working conditions. All batching plant
structures shall be maintained properly leveled within the accuracy
required by the design of the weighing mechanism.
(c) The scales for weighing aggregates and cement shall be either
of the horizontal beam or of the springless dial type, designed as an
integral unit of the batching plant, of rugged construction to withstand
hard usage due to working conditions, with a maximum allowable
error of ½ per cent of net load and with significant gradation down to
two pounds. On the horizontal beam scale, provision, such as a "tell
tale” dial, shall be made for indicating to the operator that the required
load in the weighing hopper is being approached, which device shall
indicate at least the last 200 pounds of load. A device on weighing
beams shall indicate critical position clearly. Poises shall be designed
for locking in any position and to prevent unauthorized removal.
The weigh beam and "tell tale" device shall be in full view of the
operator while charging the hopper and he shall have convenient access
to all controls.
(d) Clearance between scale parts, hoppers and bin structure shall
be such as to avoid displacement of or friction between working parts
due to accumulations, vibrations or other causes. Pivot mountings
shall be designed so none of the parts will jar loose and so as to assure
unchanging spacing of knife edges under all circumstances. Scales
shall be so designed that all exposed fulcrums, clevises and similar
working parts may readily be kept clean. Scales shall be constructed
on non-corrosive materials, excluding material softer than brass. Ten
50-pound weights shall be available for checking. Weigh beams shall
have leveling lugs, and weighing parts of other types shall be provided
with means for precision adjustment. Scales shall be "sealed" at the
expense of the contractor when required by the Engineer.
2. Moisture in Aggregate. The weights given the contractor by
the Engineer to be used in weighing out batches of the aggregate, shall
include the weight of the moisture in the aggregate. For sand weight
measurement purposes only, sand in average stock pile condition may
be assumed to contain 3 per cent of moisture. Whenever, in the opinion.
of the Engineer, the moisture content of the fine or coarse aggregate
has changed, new tests shall be made and the batch weights altered
accordingly.
3. Water Cement Ratio. (a) The proportions of fine and coarse
aggregate shall be the quantities of these materials which, with the
specified quantity of mixing water and cement, will produce a workable
and plastic concrete and a pavement free from rock pockets, honey-
combing or segregation. The quantity of water shall be the minimum
that will permit good placement.
11
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​AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
(b) The "mixing water" shall not exceed five and one-half (5½) F1
U. S. gallons per ninety-four (94) lb. sack of cement. In the southern
states, where specified by the Engineer, the "mixing water" shall not
exceed six (6) gallons per sack of cement.
(c) The concrete shall have a slump of not less than one nor more
than 2 inches where mechanical methods of finishing are used, and not
less than 2 nor more than 3 inches where hand finishing is used; when
tested in accordance with the Standard Method of Slump Test for
consistency of Portland Cement Concrete, A.S.T.M. Designation:
C143.
(d) The volume of fine aggregate shall be not less than one-half
(2) the volume of coarse aggregate nor more than the volume of
coarse aggregate, measured separately, dry and rodded.
(e) If the concrete secured with this ratio of water to cement does
not have the desired strength the Engineer may decrease the amount
of "mixing water" per sack of cement and the contractor shall be paid
for the additional cement, at the contract price bid, or the prevailing
market price when no price has been bid, required by this change in
"mixing water," content.
(f) When high-early-strength concrete is required using Standard
Portland Cement, the water cement ratio shall be reduced in accordance
with the following table by increasing the cement content of the mix-
ture, maintaining the consistency within the limits required in para-
graph (c) above and increasing mixing time to a minimum of two (2)
minutes.
Estimated Age of
Pavement when
opened to traffic
Days
3 ...
5 ...
7.
U.S. Gallons of Mixing Water per 94-Pound
Sack of Standard Portland Cement
Average Temperature of Concrete during
Curing Period
50° F.
4+2 lb. calcium
chloride
.. 4
.434
70° F.
434+2 lb. calcium
chloride
43/4
52
The age at which the pavement may be opened to traffic shall be de-
termined by the use of test specimens as described in Section XII, 6.
(g) When high-early-strength concrete is required using high-
early-strength portland cement, the provisions of paragraphs 3, (a);
3, (b); 3, (c); 3, (d) and 3, (e) shall apply except for the change in the
type of cement. The age at which the pavement may be opened to traffic
shall be determined by the use of test specimens as described in Section
XII, 6.
(Where it is desirable to specify a Designed Mixture for Specified
Unit Cement Content instead of the water cement ratio, the foregoing
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
paragraphs 3, (a) to (g) inclusive, shall be omitted and the following F1
paragraphs 3, (a) to (f) inclusive shall be used.)
3. Designed Concrete Mixture. (a) The concrete shall consist
of a designed mixture of portland cement, fine aggregate, coarse
aggregate and water. The proportions of fine aggregate to coarse
aggregate shall depend upon the grading of these materials and shall
be the quantities of these materials which with the specified consistency
and specified unit cement content, will produce a workable and plastic
concrete and a pavement practically free from rock pockets, honey-
combing or segregation.
(b) The concrete mixture shall have a unit cement content of
6.0 bags of cement per cubic yard of concrete in place. In the
southern states, where specified by the Engineer, a unit content of
5.5 bags of cement per cubic yard of concrete in place may be used.
The field proportions shall be reduced to the weight basis as specified,
for each size of aggregate, allowance being made for the weight of
moisture in the aggregates which shall be determined periodically by
the Engineer. With the usual aggregates (assuming a specific gravity
of 2.65), a unit cement content of 6 bags gives approximate quantities
of cement, water and dry aggregates for one cubic yard of concrete in
place as follows: 6.0 bags (564 lb.) of cement, to 33.0 gallons of
water (5.5 gallons of free water per bag of cement), to either 1245 lb.
of dry fine aggregate and 1980 lb. of dry stone or 1155 lb. of dry fine
aggregate and 2070 lb. of dry gravel (assuming air to occupy 0.75%).
The proportions of fine aggregate and coarse aggregate shall be
varied by the Engineer to give a dense and workable concrete, care
being taken not to oversand the mixture, but in no case shall the propor-
tion be varied so as to change the specified unit cement content per unit
volume of concrete. The quantities for each batch, except when using
bulk cement, shall be exactly designed to be used with either one or
more sacks of cement. Fractional bags of cement may be used pro-
vided they are accurately weighed and are handled in a manner meet-
ing the approval of the Engineer.
(c) The smallest quantity of mixing water that will produce a plastic
workable concrete mixture under the conditions of use shall at all times
be required by the Engineer. The consistency of the mixture shall be
uniform and such that the mortar in the concrete shall cling to the
coarse aggregate. The concrete shall not be sufficiently wet to flow
readily and segregate, nor of a mealy dry consistency. The concrete
shall have a slump of not less than one nor more than 2 inches where
mechanical methods of finishing are used, and not less than 2 nor more
than 3 inches where hand finishing is used; when tested in accordance
with the Standard Method of Slump Test for Consistency of Portland
Cement Concrete, A.S.T.M. Designation: C143.
(d) The field Engineer shall calculate the volume of concrete pro-
duced per sack of cement by adding together the absolute volumes of
cement, water, fine and coarse aggregates, which are combined to pro-
duce the concrete. The sum of these absolute volumes shall be con-
sidered the "yield" of the concrete per sack (94 lb.) of cement.
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
When the unit cement content thus determined is less than that speci- F1
fied herein, the proportions of the mixture shall be corrected accord-
ingly so as to give the specified unit cement content. Any overrun of
cement used, in excess of five (5) per cent of the specified amount, as
so calculated by the Engineer, will not be paid for when the cement
is paid for separately from the concrete in place.
(e) Where high-early-strength concrete is desired, using standard
portland cement it shall be proportioned as indicated in the following
table, for normal average temperatures during the curing period (as-
suming a specific gravity of 2.65 for aggregates and air occupying
0.75 per cent).
Estimated Age When
Pavement may be
Opened to Traffic
(approximately 550 lb. Bags
modulus of rupture)
Cement
3 days
7 days
7.2*
6.6
Water
Gallons
33.1
33.3
Stone Aggregate
Quantities per Cubic Yard of Concrete
Gravel Aggregate
Dry Fine
Aggregate
Lb.
Dry Fine
Aggregate
Lb.
1140
1190
Dry
Stone
Lb.
1980
1980
1050
1100
Dry
Gravel
Lb.
2070
2070
* For temperatures less than 70°F., 15 pounds of calcium chloride will also probably be
required.
(f) Where high-early-stength concrete is desired using high-early-
strength portland cement, the provisions of paragraphs 3, (a); 3 (b) ;
3, (c) and 3, (d) shall apply except for the change in the type of cement.
The age at which the pavement may be opened to traffic shall be de-
termined by the use of test specimens as described in Section XII, 6.
IX. MIXING CONCRETE
1. General. (a) The methods used in storing, handling and meas-
uring materials for the concrete, including water, shall be such as will
insure a uniform, homogeneous mixture at all times.
(b) Storage, Handling and Transportation of Cement. The con-
tractor shall protect the cement against damage from moisture.
During transportation from the proportioning plant to the mixer,
cement may be kept in a weather-proof compartment separate from the
aggregate, or be covered by part of the aggregate. Cement may also be
transported separately to the mixer provided it is properly protected.
If placed in contact with the aggregate, the entire batch of materials
shall be placed in the mixer before the expiration of two (2) hours.
Ninety-four (94) pounds of cement (one bag or 4 barrel) shall be
considered as one cubic foot.
(c) Aggregates. Aggregates shall not be piled on the prepared
subgrade. Aggregate stock piles shall be located at points approved by
the Engineer and so arranged that fine and coarse aggregates or coarse
aggregates separated by specification requirements do not become
mixed.
If deliveries of aggregate show segregation of sizes, material shall be
deposited in stock piles and mixed before using. Aggregates shall be
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
deposited in layers, not more than three feet thick, uniformly across F1
stock piles, to minimize segregation of coarse material rolling down
the sides of the pile.
The contractor shall provide either approved platforms or a prepared
base satisfactory to the Engineer; or at least 6 inches of the base of
the stock pile material shall be left undisturbed until the completion
of the pavement and structures.
Materials from different sources of supply shall not be stored in the
same stock piles unless approved by the Engineer.
All materials shall be so handled as to prevent loss or overrun of
aggregates or cement, in batches, during transit, or while dumping at
the mixer. Suitable provision shall be made to protect materials in
transit from wind or rain.
2. Mixing and Mixing Equipment. (a) The concrete shall be
mixed in a batch mixer. If the mixer is not of the stationary type it
shall have a rated capacity of 27 cubic feet or 34 cubic feet of mixed
concrete and shall have a boom and bucket discharge. Mixers having
dual mixing drums of approved design may be used. Mixing of the
batch shall continue for at least one minute after all the cement,
fine and coarse aggregate are in the drum and before any part of the
batch is discharged.
Water shall be introduced into the drum before the cement and ag-
gregates and continuously from that time until not less than 5 nor more
than 10 seconds after the cement and aggregates are in the drum. The
entire contents of the drum or of each single compartment of a dual
drum mixer shall be discharged before the succeeding batch is intro-
duced.
The speed of the mixer drum in revolutions per minute shall con-
form to the rating of the manufacturer. The volume of mixed concrete
in each batch shall not exceed the mixer manufacturer's rated capacity
for the drum by more than ten (10) per cent.
Concrete which has been mixed longer than 30 minutes or which has
developed initial set shall not be used.
(b) The mixer shall be provided with a water measuring device.
which will consistently measure the water going into the mixer drum
to within one (1) pint of the desired amount for each sack of cement
in the batch. The water measuring device shall be subject to adjust-
ment by the Engineer. The mixer shall not be operated unless the
water measuring device is functioning properly, nor when leaking
valves pass unmeasured water into the drum.
(c) The mixer shall be provided with a batch timing device which
will automatically lock the batch discharging device during the full
mixing time and release it at the end of the mixing period. The timing
device shall have a bell which will automatically ring at the end of the
mixing period. The timing device shall be subject to inspection and
adjustment by the Engineer at any time. The mixer shall not be
operated unless the timing device is functioning properly.
3. Central Mixed and Mixed in Transit. The use of central
mixing plants and transporting equipment, and the use of truck mixers
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
or truck agitators is permitted under these specifications provided F1
there is no segregation of material when the concrete is deposited on
the subgrade. The concrete shall conform to Tentative Specifications
for Ready-Mixed Concrete, A.S.T.M. Designation: C94.
The time lapse from the addition of the water until depositing on
the subgrade shall not exceed 20 minutes when concrete is hauled in
nonagitating trucks or 30 minutes when hauled in truck mixers or
agitating trucks. The concrete shall be deposited in a plastic and work-
able condition and its slump shall be within the limits previously
specified.
4. Retempering. Retempering of mortar or concrete which has
partially hardened, that is, remixing with or without additional ma-
terials, or water, will not be permitted.
X. DEPOSITING CONCRETE
1. General. Immediately prior to placing the concrete, the sub-
grade shall be brought to an even surface and checked with an approved
template before any concrete is laid.
2. Conditions of Subgrade. Concrete shall be placed only on a
moist subgrade, but there shall be no pools of standing water. If the
subgrade is dry, it shall be sprinkled with as much water as it will
absorb readily. The Engineer may direct that the subgrade be
sprinkled or thoroughly wetted from twelve (12) to thirty-six (36)
hours in advance of placing concrete, where such procedure is neces-
sary. Sprinkling shall be done in such a way that no mud or dirt is
thrown onto the edge of the concrete or against the forms by the
stream of water.
3. Placing Reinforcement. If steel reinforcement is used it shall
be of the effective area and spacing shown on the plans for the im-
provement. The reinforcement shall be so placed that it shall be two
(2) inches below and parallel to the finished surface of the pavement,
unless otherwise shown on the plans.
(a) Fabric reinforcement shall be placed on a first layer of concrete
which has been struck off at the correct elevation to permit the location
of the fabric in the position specified, or with the approval of the
Engineer, may be securely supported in the proper position before any
concrete is placed. All adjacent fabric sections shall be lapped as
required in Section II, 4, (a).
(b) Bar mat reinforcement shall be placed as specified above for
steel fabric. Adjacent bar mats shall be lapped as required in Sec-
tion II, 4, (c) and (d).
(c) The width and length of fabric sheets or bar mats shall be such
that, when properly placed in the work, the extreme longitudinal and
transverse members will be located approximately three (3) inches
from the edges of the slab, unless otherwise shown on the plans.
4. Depositing Concrete. The mixed concrete shall be deposited
rapidly on the subgrade to the required depth and for the entire width
of the pavement section, in successive batches and in a continuous
operation, without the use of intermediate forms or bulkheads between
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
joints. A mechanical concrete spreader may be used for placing the F1
concrete. When machine finishing or hand finishing is used, the con-
crete along side forms, longitudinal joints and transverse joints shall
be compacted by a vibrator inserted in the concrete. When the con-
crete is placed in two (2) horizontal layers to permit use of steel re-
inforcement the first layer shall be roughly struck off with a template
or screed, riding on the side forms, at the correct elevation to permit
placing the reinforcement in specified position. The concrete above
the reinforcement shall be placed within fifteen (15) minutes after
the first layer has been placed. Any dust, dirt or foreign matter which
collects on the first layer shall be carefully removed before the upper
layer is placed.
5. Breakdowns. In case of a breakdown of the mixer, involving
stopping operations for more than thirty (30) minutes, a transverse
joint shall be formed at the point directed by the Engineer. Any con-
crete in excess of that needed to form this joint shall not be used in the
pavement.
6. Cold Weather Construction. Concrete shall not be placed on
frozen subgrade or where the subgrade under adjacent pavements is
frozen. Concrete may be placed when the air temperature in the shade
and away from artificial heat is not less than 40 degrees F. and rising.
Concrete shall not be placed when the temperature is 40 degrees F. or
less and falling. The temperature of the concrete in the drum of the
mixer shall be not less than 60°F. nor more than 100°F.
XI. FINISHING CONCRETE
1. Finishing, General. The concrete pavement shall be finished
(a) by a finishing machine, (b) by hand finishing, or (c) by vibratory
compacting equipment.
2. Machine Finishing. (a) The pavement shall be struck off and
consolidated with a mechanical finishing machine. This machine shall
strike off the concrete at such a height that, after consolidation and
final finishing, it shall be at the exact elevation and have the exact
crown shown on the plans. A depth of at least two (2) inches of con-
crete shall be carried in front of the strike-off screed for the full width
of the slab, when the screed is first being used to strike off the pave-
ment.
(b) The finishing machine shall be provided with a screed which
will consolidate the concrete by pressure. The concrete shall be
brought to a true and even surface, free from rock pockets, with the
fewest possible number of passages of the finishing machine.
(c) Hand finishing tools must be kept available for use in case
the finishing machine breaks down.
(d) Immediately following the last trip of the finishing machine,
the surface of the pavement shall be smoothed and consolidated by
means of an approved self-propelled mechanical bull float or by means
of a longitudinal float. The longitudinal float shall be not less than
12 feet in length and 6 inches in width, stiffened to prevent flexibility
and warping and provided with handles at each end. The float shall be
I
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
placed on the pavement with its long axis parallel to the center line of F1
the pavement and be operated by two men, one at each end, who stand
on bridges spanning the pavement. The float shall be dragged from
edge to edge of the slab with a wiping motion; no sawing motion shall
be used. When the entire surface has been floated in this manner, the
bridges shall be moved ahead such a distance that the next section will
overlap the one previously floated by at least one half the length of the
float.
(e) After excess water has come to the surface, the pavement shall
be scraped with a straightedge from six (6) to ten (10) feet long.
The straightedge shall be operated so that all excess water, laitance
and inert matter is drawn from the surface of the pavement.
(f) Following the scraping the pavement shall be tested for irregu-
larities with a ten (10) foot straightedge. The straightedge shall
be placed on the surface parallel to the center line and at not more than
five (5) foot intervals transversely. After each test the straightedge
shall be moved forward one-half (2) its length and the operation
repeated. When irregularities are discovered, they shall be corrected
by adding or removing concrete. All disturbed places shall be floated
with a wooden float not less than three (3) feet long and not less than
six (6) inches wide.
(g) When the water sheen has disappeared from the surface of
the pavement the final finish shall be given with a wood, canvas or
rubber belt or with a strip of burlap. The belt shall be not less than
three (3) ply canvas or rubber or a board thin enough to lie flat on
the pavement, at least ten (10) inches wide and at least two (2) feet
longer than the width of the slab under construction. It shall be ap-
plied with a combined crosswise and longitudinal motion and shall
leave the surface with an even, gritty texture. When a strip of burlap
is used as the final finishing tool, it shall be at least three (3) feet wide
and four (4) feet longer than the width of the slab under construction,
and shall be kept saturated while in use. It shall be laid on the surface
of the pavement and dragged forward in the direction in which the
pavement is being laid.
3. Hand Finishing. (a) Hand finishing shall comprise the opera-
tions of striking off, longitudinal floating, scraping, testing and final
surfacing.
(b) Where hand finishing is permitted the pavement shall be struck
off with a screed, cut to the form of the pavement surface, and weigh-
ing at least fifteen (15) pounds per lineal foot. The screed shall rest
on the side forms, gutter apron or curb and be drawn forward with a
sawing motion. A depth of at least two (2) inches of concrete shall
be carried in front of the strike-off screed for the full width of the
pavement, whenever the screed is being drawn forward.
(c) In intersections where warped surfaces make it impracticable to
use a screed, the correct pavement contour may be secured by the use
of a lute. In that case steel grade stakes provided with lugs shall be
driven into the subgrade with the top of the lugs accurately set at the
18
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
elevation for the finished pavement. These stakes shall be set at F1
intervals of 10 feet along the subgrade and in a straight line perpen-
dicular to the center line of the pavement, one at the center line and
one at each quarter point and so many additional points as the Engi-
neer may direct. The concrete shall then be spread to the elevation
indicated by the stakes.
Cement mortar gathered from the surface of the concrete already
placed shall not be used in filling boot tracks or stony areas, but such
imperfections shall be dug out and refilled with concrete to the depth
of the reinforcing and worked smooth. No workman shall then be
allowed to walk over the area so completed.
(d) Following the initial screeding the pavement shall be screeded
a second time.
Tamping shall be done only after screeding, and then only when
required by the Engineer, where the mortar fails to come properly
to the surface during the screeding. A separate template may be
used for tamping, or the strike-off template may be used if it is of
suitable construction. In the tamping operation one end of the tem-
plate shall rest on the side form or edging, while the other is lifted
and dropped, advancing at such a rate that the whole surface is struck
at least once. The opposite end shall then be lifted and dropped in
the same manner. Neither end shall be advanced more than one (1)
foot ahead of the other.
(e) Following the second screeding, the pavement shall be floated
longitudinally, as specified above under paragraph 2, (d).
(f) After excess water has come to the surface the pavement shall
be scraped with a straightedge as specified above under Section 2, (e).
(g) Following the scraping the surface shall be straightedged,
corrected and disturbed places floated and final finishing applied as
specified above under paragraph 2, (f) and (g).
4. Vibratory Compacting and Finishing. (a) The concrete shall
be struck off and screeded by a mechanical finishing machine and vi-
brated and consolidated by vibratory compacting equipment of the
screed or pan type designed to operate at a frequency of not less than
3500 cycles per minute. The strike off and screeding shall conform to
the crown and cross section shown on the plans, and shall be performed
at such elevation slightly above the grade that when consolidated and
finished, the surface of the pavement will be at the elevation shown on
the plans. A depth of at least 3 inches of concrete shall be carried in
front of the strike off screed for the full width of the slab when the
screed is first being used to strike off the pavement, but the depth shall
not exceed two-thirds of the height of the vertical face of the screed.
(b) The vibratory action shall be applied to the concrete during one
or more passes of the vibratory compacting equipment until a density
approved by the Engineer has been obtained. Internal vibration along
side forms, longitudinal joints and transverse joints will be required
only where the vibratory compacting equipment does not provide the
required density at these locations. Concrete which is inaccessible to
the vibratory compacting equipment shall be vibrated either on the sur-
face or internally with a vibrator.
19
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AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
Where fabric reinforcement is used, the lower layer of the concrete F1
shall be struck off to the required elevation by a mechanically operated
strike-off templet, and the lower layer shall not be struck off or com-
pacted by the vibratory compacting equipment.
(c) Hand finishing tools must be kept available for use in case the
vibratory compacting or finishing equipment breaks down.
(d) Following the final screeding, the pavement shall be floated
longitudinally, as specified under paragraph 2, (d).
(e) After excess water has come to the surface, the pavement shall
be scraped with a straightedge as specified under paragraph 2, (e).
(f) After the scraping, the surface shall be straightedged, corrected
and disturbed places floated, and final finishing applied as specified
under paragraphs 2, (f) and 2, (g).
(The following will be included when a "broomed" surface finish
is desired.)*
5. Brooming. For the final finishing operation, the surface shall
be broomed. The broom shall be not less than 18 inches in width, and
made from a good quality bass or bassine fiber not more than 42
inches long. The broom shall be dragged from the center lines to the
edges of the slab, at such time and in such a manner that any excess
water or laitance is removed and the surface is left a succession of
small ridges and hollows, running approximately at right angles to the
center line. The broom shall have a handle at least 2 feet longer than
the distance from the center to the edge of the slab. The broom shall
be maintained in good usable condition at all times by being washed
and dried at frequent intervals.
XII. CURING, PROTECTION AND OPENING TO TRAFFIC
1. Curing of Concrete. (a) Curing shall continue for the periods
specified under the individual curing method, except that under ex-
tremely dry or cool weather conditions the Engineer may require addi-
tional curing periods, additional covering, or both, or, if the time for
opening the pavement to traffic is to be determined by test specimens,
the specified curing shall continue until the concrete specimens meet
the requirements specified below in paragraph 6, Opening to Traffic.
(b) Immediately after the finishing operations have been com-
pleted and regardless of the method of final curing, the entire surface
of the newly laid concrete shall be covered with wetted burlap or
cotton mats laid directly upon the finished surface. This covering
shall be kept continuously saturated with water until removed. It
shall not be allowed to become displaced or be removed earlier than
the morning of the day following its application.
(c) In all cases curing shall have prior rights to all water supply
or supplies. Failure to provide sufficient approved burlap or cotton
mats and maintain the protection as prescribed, or lack of water supply
capacity to take care of both curing and other requirements, shall be
cause for immediate suspension of concreting operations. The man-
* See Appendix I.
20
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
ner of laying the covering and the arrangement of the strips shall be F1
as required by the Engineer to best accommodate the necessary surface
testing, joint trimming and other operations. Water shall be applied
by a spray fine enough to avoid damage to the fresh concrete. The
strips of burlap or cotton mats must be laid to overlap 6 inches to pre-
vent occurrence of gaps or uncovered spots during the curing.
(d) The burlap shall be of 10 to 18-ounce weight per 10 square
feet or two layers of 6 or 7-ounce burlap may be used. If furnished
in strips they shall be in no case less than 3 feet in width and for
transverse laying not less than 3 feet longer than the width of the slab
being cured. Worn burlap, burlap with holes, burlap reclaimed from
other uses than that of curing concrete will not be permitted. New
burlap having "misprint" brands or stenciling will be permitted.
(e) The cotton mats shall have a finished width of approximately
5 feet 6 inches and a length 2 feet greater than the width of the
pavement to be cured. The mats shall be composed of a single layer
of cotton fibre weighing not less than 3/4 of a pound per square yard
of mat and completely enclosed in covers of cotton cloth or burlap.
The mats shall be securely stitched along both edges and longitudi-
nally in parallel rows at intervals of not more than 4 inches, or shall
be tufted both transversely and longitudinally at intervals of not
more than three inches. The stitching or tufting shall not be done so
tightly that the mat will not make a thorough contact with the surface
of the pavement at all points when saturated with water. To insure
complete covering of the pavement there shall be a flap 6 inches wide.
extending along one side of each mat. This flap shall be composed
of two thicknesses of the cover material and shall be strongly stitched
along the edge so that it will lie flat on the pavement.
(f) Except when final curing is done by use of burlap or cotton
mats the slab shall be thoroughly wetted upon the removal of the cover-
ing and then cured by one of the following methods of final curing.
In no case shall any concrete, at either top or edge of slab, be left
unprotected for more than ½ hour. Minimum curing periods when
high-early-strength concrete is used shall be until the pavement may
be opened to traffic, as determined by the use of test specimens as de-
scribed in Section XII, 6.
2. Burlap or Cotton Mat. The burlap or cotton mats covering
placed on the pavement as hereinbefore specified shall be kept saturated
with water both day and night, including Sundays and holidays, for a
period of at least 72 hours after the concrete is placed. After the
forms are removed the covering shall be folded down and held in con-
tact with the edges of the slab.
3. Wet Earth or Straw Curing. Immediately upon the removal
of the burlap, or cotton mats, the exposed edges of the slab shall be
banked with a substantial berm of earth and the entire surface of the
pavement shall be covered with earth not less than 1½ inches in
depth. The earth covering shall be thoroughly wetted while it is being
placed on and against the sides of the slab and kept completely and
21
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
continuously saturated for three days and left saturated at the be- F1
ginning of the fourth day, dating from the time of the removal of the
burlap. If the earth covering becomes displaced during the curing
period it shall be replaced to the original depth and resaturated. Clean,
ĺdose straw at the rate of 6 pounds to the square yard may be substi-
tuted for the earth material and saturated`under the same require-
ments. In any case, the covering shall remain on the pavement until
permission is given to open the pavement to traffic, at which time the
covering shall be removed and the pavement cleaned and swept.
4. Sprinkling System of Curing. After the removal of the bur-
lap, or cotton mats, sprinklers may be used if approved by the Engineer.
The sprinkling equipment shall be placed carefully, and without in-
juring the concrete surface. The sprinkling system shall be so ar-
ranged and supplied with sufficient water at ample pressure, to keep
every portion of the pavement continuously wet, both day and night,
for four days from the time the slab is finished. Water flowing off
the surface of the pavement shall be delivered to the ditches or drains
as directed by the Engineer. The contractor shall be held responsible
for any damage to the roadway, shoulders or adjacent property, by
reason of escaping water.
5. Ponding Method. Immediately after the removal of the bur-
lap or cotton mats the exposed edges of the slab shall be banked with
a substantial berm of earth and the entire surface of the pavement shall
be flooded with water which shall be ponded by means of a system of
transverse and longitudinal dikes or dams of earth or other material.
Water shall be maintained at such depth that the pavement will be
completely submerged throughout the period of curing. The curing
shall continue four days, dating from the time the slab is finished.
Before the pavement is opened to traffic, the material composing the
dams or dikes shall be removed from the surface and the pavement
cleaned.
6. Opening to Traffic. Traffic shall be excluded from the newly
constructed pavement for a period of 10 days after the concrete is
placed or longer, if, in the opinion of the Engineer, weather conditions.
make it advisable to extend this time, except, however, at the discretion
of the Engineer, concrete strength tests made upon cross-bending test
specimens or standard six by twelve inch compression specimens, pre-
pared at regular intervals, cast from the concrete going into the pave-
ment and cured under the same temperature, moisture and climatic
conditions as the corresponding slabs of pavement, may be employed
as a means of fixing the time of opening to traffic. These beams or
cylinders will be tested by standard laboratory methods and when
these specimens under test indicate that, prior to the expiration of the
10-day period, the corresponding pavement has attained a modulus of
ruptures of not less than 550 pounds per square inch (A.S.T.M. Desig-
nation: C78) and a compressive strength of not less than 3500 pounds
per square inch (A.S.T.M. Designation: C39). In all cases before
the pavement is opened to traffic it shall be cleaned and the joints shall
22
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
be filled and trimmed or topped out as herein required. The joint or F1
line of separation between adjacent strips or slabs of concrete, when
the pavement is constructed in lanes or strips, shall be cleaned and
filled with bituminous material herein prescribed for the purpose.
7. Protection of Concrete. The contractor shall erect and main-
tain suitable barricades and employ watchmen, if required by the Engi-
neer, to exclude traffic from the newly constructed pavement for the
period herein prescribed but these barriers shall be so arranged as not
in any way to interfere with or impede public traffic on any lane in-
tended to be kept open and necessary signs and lights shall be main-
tained by the contractor clearly indicating the open lanes to the public.
When it is necessary to provide for traffic across the pavement, the
contractor shall at his expense construct suitable and substantial cross-
ings to bridge over the concrete which will be adequate for the traffic
and satisfactory to the Engineer. Any part of the pavement damaged
by traffic or other causes occurring prior to its final acceptance shall
be repaired or replaced by and at the expense of the contractor in a
manner satisfactory to the Engineer. The contractor shall protect
the pavement against both public traffic and the traffic caused by his
own employees and agents. All ditches and drains shall be in such
condition as to provide effective drainage. When berms of earth are
placed along the shoulders, proper provision shall be made for sur-
face drainage.
Except where a special bid price for "maintenance of traffic" is re-
quired in the proposal, all cost and extra expense of maintaining of
traffic and protection, special equipment and temporary road surfacing
and maintaining of traffic and protection, shall be at the expense of
the contractor.
XIII. ACCEPTANCE
Cores may be taken from the finished concrete pavement previous to
acceptance, and the acceptance of the pavement may be governed by
the quality and thickness as shown by the cores. Slabs of pavement
which are found to be more than one-half (½) inch short of the
specified thickness shall be removed and replaced at the contractor's
expense with concrete of specified quality and thickness. If, however,
in the opinion of the Engineer, there is no probability of immediate
failure of such deficient slabs, he may allow the contractor the choice
of leaving the defective slabs in place and receiving no compensation
or payment for the same, or of replacing the pavement slab as provided
for above.*
The surface shall be tested by means of a 10 foot straightedge placed
parallel to the center line of the pavement, parallel to the grade line
and touching the surface. This test shall be applied in each wheel
lane. For every variation from the true surface greater than % and
less than ½ inch, there shall be deducted from the amounts due the
contractor the cost of one square yard of pavement. If the variation
See Appendix I, 7, (e).
23
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
F1
from the true surface is ½ inch or greater, the entire area shall be re-
moved and replaced at the entire expense of the contractor. Any areas
so removed shall be not less than 10 feet in length nor less than the
full width of the traffic lane involved.
Appendix I
RECOMMENDATIONS ON DESIGN
The principles of the design of concrete pavements as outlined herein
have been evolved gradually from independent sources, by observation,
experiment and theoretical considerations, and are assembled in this
section for the convenience and guidance of the Engineer.
1. Subgrade Study. Previous to the construction of the concrete
pavement it is desirable to have a subsoil study made by the testing
laboratory to determine the quality of the subsoil beneath the pave-
ment. Such a study will often show the desirability of placing proper
drainage courses or subbases before the pavement slabs are laid.*
2. Pavement Cross Section. It is recommended that the thickness
of all pavement slabs be not less than that determined by the following
equations:
(a) For Protected Corners-Pneumatic Tires.
1.92Wc
S
d₁=
(Equation No. 1)
In which: d₁ depth of uniform slab thickness in inches. (When
designing structurally balanced thickened edge section,
the edge thickness is 1.275d₁ and center thickness is
0.85d₁ where the thickening is obtained by a straight
slope in the outer 2 ft.)
W static wheel load in pounds.
S=allowable unit working stress in lb. per sq. in.
modulus of rupture
safety factor
=
c=coefficient of subgrade support which is 1.0 for soft
and plastic subgrade having a bearing power of 10 lb.
per sq. in.
* The APWA Specifications Committee on Cement Concrete Pavements (1944)
suggested the following revisions in A.P.W.A. Specification B-1, Earth Sub-
grade: Article 11. "All fills exceeding 6 inches in height shall be made in layers
not more than 6 inches thick and shall be compacted by means of a three-wheel
roller weighing not less than 10 tons or a tamping or pneumatic-tired roller."
Article 19. "Before the subgrade will be considered ready for the pavement or
base course, it shall be compacted with a three-wheel roller weighing not less
than 3 tons nor more than 5 tons. Where the subgrade is composed to a large
extent of sand or gravel, a 10-ton roller shall be used."
24
Jo
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
Other values are:
c=1.096 for 5 lb. per sq. in. for very soft and plastic
subgrade
=0.9 for 20 lb. per sq. in. for fairly hard subgrade
=0.842 for 30 lb. per sq. in. for hard subgrade
-0.80 for 40 lb. per sq. in. for very hard subgrade
=0.77 for 50 lb. per sq. in. for extremely hard gravel
or macadam subgrade.
(b) For Unprotected Corners-Pneumatic Tires.
d2=
In which:
2.4Wc
S
(Equation No. 2)
d2=depth of a uniform slab thickness in inches (when
designing structurally balanced thickened edge sec-
tions, the edge thickness if 1.212d2 and center thick-
ness is 0.76d2 when the thickening is obtained by a
straight slope in the outer 3 feet.)
W static wheel load in pounds.
S=allowable unit working stress in pounds.
per sq. in.=modulus of rupture
safety factor
c=coefficient of subgrade support (see values under (a)
above.)
Equation No. 1 (Protected Corners) applies to the design of pave-
ment slabs where corners formed by the intersection of transverse
joints or cracks with the edges of the pavement or free longitudinal
joints, are provided with adequate means of load transfer across the
joint or crack, such as dowel bars, marginal bars or designs providing
mechanical interlock which insures adequate load transference.
Equation No. 2 (Unprotected Corners) applies to the design of
pavement slabs where corners are not protected by some adequate
means of load transfer.
The wheel load (W) should be taken as one-half the legal axle load
for heavy duty streets. For other streets the wheel load (W) should
be taken as one-half the axle load of the heavier trucks or busses that
will use the streets.
The safety factor equals the modulus of rupture of the concrete
divided by the allowable working stress, (S.). When the working
stress does not exceed 50 per cent of the modulus of rupture, or when
the safety factor is 2 or more, the concrete will stand an unlimited
number of stress repetitions without failure through fatigue. When
the stress materially exceeds 50 per cent of the modulus of rupture,
or the safety factor is less than 2, continued repetitions will eventually
cause failure, the number of stress repetitions which will eventually
cause failure decreasing as the stress approaches the modulus of
rupture or the safety factor approaches 1.
F1
25
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
All pavement slabs should be designed to carry the predominating F1
wheel loads with a factor of safety of at least 2.
The modulus of rupture should be determined on test specimens
of the concrete to be used for the work.
Note: The above design procedure gives pavement thicknesses due
to load only. Additional thickness will be required to provide for
warping stresses caused by temperature.
3. Width of Pavement Slabs. The width of the pavement is
necessarily determined by traffic and economic conditions. Traffic
lanes of 10, 11 or 12 feet should be used depending upon the volume of
heavy weight truck and bus traffic. It is recommended that longi-
tudinal joints divide pavements into traffic lanes and parking lanes.
An 8 foot parking lane is recommended and it is recommended that
the maximum distance between the longitudinal joints be 15 feet.
4. Crown and Surface Drainage. A suitable crown in inches for
a concrete street pavement may be determined approximately by di-
viding the width of the pavement between curbs in feet by the
factor 10.
Where the pavement surface is carried in a straight slope from
center line to gutter, a slope of three-sixteenths of an inch per foot
is satisfactory to provide sufficient drainage.
The crown or contour of the pavement may either be formed
by two or more planes, depending upon the number of slabs, or a curve
for the flat slopes used on concrete pavements. A circular curve
formula and the parabolic formula give practically similar results,
the latter curve, however, being easier to figure.
It is recommended that the crown or cross-section of the pavement
surface be formed by plane slabs sloped from the center of the pave-
ment to the first longitudinal joint at the rate of 1% inch per foot of
width and from the first longitudinal joint to the gutter at the rate of
14 inch per foot of width.
In general the gutter slope or grade should never be less than 1 to
300. Where the grade of the street is so flat as to prevent drainage
in the direction of the slope within this limit it will be necessary to
properly drain the pavement to vary the curb depth from, say, three
to six inches within this limitation for minimum grade of 1 to 300,
keeping the center of the crown at a grade parallel to the curb grade.
On a perfectly flat grade this would place the surface sewer inlets 150
feet apart with the minimum gutter half-way between the surface
sewer inlets.
5. Reinforcement. It is recognized that one of the functions of
steel in pavement slabs is to prevent the widening of contraction cracks,
and it is believed that the steel may also aid in the prevention or
diminution of cracks formed during the period of curing. The relief
of the first condition may be accomplished by using sufficient steel so
that, when contraction of the slab takes place, the steel across a crack
or joint, located midway between the edges or joints, will not be over-
stressed because of the friction developed between the pavement and
subgrade.
26
छ
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
(a) It is recommended, therefore, that the area of both transverse F1
and longitudinal steel be proportioned in accordance with the follow-
ing equation:
(Equation No. 3)
Where:
1 wc
As = 2 fs
As
is the area of steel in square inches per foot of width,
running in the direction in which 1 is measured.
1
is the length in feet (or width, for transverse steel)
of the slab between joints across which no bonded steel
is placed.
is the weight of slab in pounds per square foot.
is the coefficient of friction of the concrete slab on
the subgrade soil. A coefficient of 1.0 is recom-
mended.
fs is the allowable unit tensile stress in the steel. As-
sume 25,000 lb. per square inch for structural grade
axle or billet steel; 30,000 lb. per square inch for in-
termediate grade axle or billet steel; and 35,000 lb.
per square inch for hard grade axle or billet steel, or
for rail steel, or cold-drawn steel wire.
W
с
(b) Where no transverse joints are used, the above method of
designing reinforcement will not apply.
(c) Tie Bars across Longitudinal Joints. Tie bars across longi-
tudinal hinged joints are installed to prevent the separation of the
slabs on either side of the joint which would destroy their load dis-
tributing ability. They must have sufficient bond and strength to pull
the concrete on either side of the joint over the subgrade as the joint
tends to open with subgrade settlement or contraction of the concrete.
The required amount of steel in tie bars expressed in square inches
of steel per foot length of joint is then :
(Equation No. 4)
Ag=
The letters have the same meaning as in formula for reinforcement
(Equation No. 3). "b" is taken as the distance in feet from the
longitudinal joint in question to the nearest longitudinal joint not held
together by tie bars, or to the free edge of the slab. The area of indi-
vidual bars and the spacing between bars may then be selected so that
the required area of steel per foot length of joint is secured.
Tie bars shall be placed midway between top and bottom of the
slabs perpendicular to the joint. Deformed bars should be used for
the tie bars. The embedment of the tie bars should be calculated
by assuming a bond stress, in pounds per square inch of bar surface,
of 5/100 of the 28 day compressive strength of the concrete.
To avoid excessive tension in the concrete not more than three lane
wcb
fs
27
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
widths of pavement should be tied together with tie bars. In pave- F1
ments of greater widths a free joint should be used with thickened
edges constructed with a key to avoid differential settlement, or with
slabs of uniform thickness contraction or shrinkage joints with slip
dowels may be used.
(d) Dowel Bars. It is recommended that dowels across expansion
joints be 3/4 inch round smooth bars 18 inches long and spaced at inter-
vals from 12 to 15 inches.
6. Materials. (a) In many cases, it will be necessary for the
Engineer to specify the sizes, grading and quality of fine and coarse
aggregate in accordance with local conditions. In every case, the
Engineer should provide specifications which will require the use
of the best fine and coarse aggregate which is economically available.
The preceding specifications covering size and grading of coarse ag-
gregate calls for Combined Sizes No. 234 A or 345 B of the Simplified
Practice Recommendations of the National Bureau of Standards, U. S.
Dept. of Commerce, and will be found applicable in most sections of
the country, and are intended for use with 1:2:2, 1:2:3 or 1:12:3
mixtures.
(b) Chatts, or tailings, are terms locally applied to by-products, or
waste products, of certain mining and industrial operations. When
used as coarse aggregate for concrete pavements, special grading limits
should be specified by the Engineer.
(c) In concrete mixed at such dry consistencies as those measured
by slumps between one and three inches, it will often be desirable to
pre-wet the coarse aggregate to eliminate absorption of the mixing
water with the subsequent possibility of checking in the pavement
surface.
7. Proportioning Concrete. (a) Batching Concrete. Where
batching by weight is not practicable, batching by accurate volumetric
apparatus may be used by permission of the Engineer, if grading of
aggregates and moisture content remain reasonably uniform. Uni-
formity of batches should be checked by weighing the batch boxes or
trucks at intervals.
Cement shall preferably be emptied directly from bags into the
charging skip of the mixer, except where bulk cement is used.
(b) Average Strengths. The requirements of a given strength at
14 days, 21 days or 28 days is not entirely satisfactory since this will
vary somewhat with the materials employed and considerably with
the temperature during the curing period. The following curves show
strength for given water cement ratio and curing temperature which
may be expected with average materials, good workmanship and care-
ful control.
(c) Concrete of the approximate proportions 1:13:3 as given in
Section VIII, 3, (a) with consistency as specified, properly cured at
normal temperature, should have a minimum compressive strength
of 3,500 pounds per square inch for laboratory specimens made and
cured in accordance with the A.S.T.M. Designation: C31, and tested
28
A
A
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
}
in accordance with A.S.T.M. Designation: C39. Cylinders cut from F1
the finished pavement, in accordance with the A.S.T.M. Designation :
C42 and tested in the same manner should give corresponding
strengths, when corrected for length ratio in accordance with the

Compressive Strength-laper sq. in.
6000
5000
4000
3000
2000
1000
70°F.
60
50°
40°
70°F
60°
50°
40°
28 day
STRENGTH.
5
3-day
STRENGTH
7
6000
5000
4000
3000
2000
1000
70° F
60°
50°
6
4
6
Water-Cement Ratio -Gallons per sack.
American Society for Testing Materials specification. Ordinarily
such concrete should not require in excess of 5½ U.S. Gallons of water.
per sack of cement, including water on the surface of the aggregates,
for a plastic workable mix.
(d) Field Testing. A number of different models of portable beam
testing machines are available for use in the field. Their accuracy
may be affected by wear in the field, frequent transportation, design
of the machine, etc., and it is desirable that they be recalibrated from
time to time with standard laboratory tests.
40°
7-day
STRENGTH
(e) Coring Finished Pavement. Wherever a coring machine is
available, it is recommended that cores be cut from the finished pave-
ment as a check on the thickness laid, then capped and broken as a final
test of the compressive strength developed in the pavement slab. The
knowledge that cores will be cut and tested is a valuable safeguard
against carelessness during construction. For specifications covering
tolerance in pavement thickness, see the Typical Specifications for
Concrete Pavements issued by the American Association of State
Highway Officials or the Specifications for Concrete Pavements in
Municipalities, of the American Concrete Institute.
8. Provision for Expansion. The ordinary design of expansion
joints allows for a free expansion space of approximately 3/4 inch per
100 feet of pavement.
29
AMERICAN PUBLIC WORKS ASSOCIATION SPECIFICATIONS (1944)
9. Finishing Concrete. A broomed surface provides better trac- F1
tion on steep grades. Surveys of existing pavements seem to indicate
that brooming removes laitance and so prevents scaling. It also is
recommended as the final finish for airport runways because it diffuses
the light used to illuminate the field; and it is even claimed that
broomed pavements are more easily seen in the light from automobile
headlamps. Many engineers specify brooming for all pavements;
others require it only on the steeper grades.
10. Calcium Chloride Accelerator. Sometimes calcium chloride
is recommended in amounts of not over two pounds per bag of cement
of calcium chloride for use in high-early-strength concrete as an
accelerator. However, in view of the difference in action with different
brands of cement, it is recommended that preliminary experiments
be carried on by a laboratory previous to its use.
11. Curb and Curb and Gutter. (a) Precast or Stone Curb. It
is usually considered the best practice to set precast concrete curb or
cut stone curb after the pavement slabs have been constructed. Such
curbs should be set in a concrete cradle and preferably under-drained,
with the drains connected to the surface sewer inlets.

(b) Tie bars. It is recommended that tie bars, connecting the pave-
ment slab with separate curb or gutter slab, shall be ½-inch deformed
bars, spaced not more than three feet apart, and shall extend at least
one foot into the slab and to within three inches of the outer edge of
curb and gutter or gutter.
12. Filling Joints and Cracks. The softening point and penetra-
tion, at various temperatures, of bituminous joint fillers, must be se-
lected so that the material is not too hard and brittle to be of value at
winter temperatures and still not too soft at summer temperatures.
Other grades of bituminous joint filler than the asphalt filler (blown
type) as herein specified, might prove more suitable under local con-
ditions, especially in southern or northern cities. Elastic fillers are
preferably installed while compressed, so that when the joint opens be-
yond its initial width, the filler will expand and keep the joint filled.
Such joints should be installed compressed to about 80 per cent of their
initial thickness prior to such installation. Elastic fillers which are in-
stalled without compression or not of the pre-compressed type, or not
attached to each side of the joint or slab, should be sealed with bitumi-
nous filler.
30
UNIVERSITY OF MICHIGAN
3 9015 00756 7756
DATE DUE
17