FORMS FOR SPECIFICATIONS, ETC., FOR ROAD MATERIALS. 
17 
Methods or 
jsampl ing and 
testing. 
Per cent, 
means of a laboratory sieve, shall 
meet the following requirement: 
Total passing 200-mesh sieve to 
The gravel shall be sampled for quality and grading in ac- 
cordance with the method described on page , paragraphs 
, of these specifications ; and the grading of the gravel 
shall be determined in accordance with the method described or 
referred to on page of these specifications, test No. 
SPECIFICATION FOR GRAVEL AGGREGATE FOR LARGE AGGREGATE BITUMINOUS 
CONCRETE. 
The gravel aggregate shall consist of sound, hard, durable rock, General. 
of high resistance to abrasion,* and shall contain no particles of 
shale, slate, coal, or other materials which easily disintegrate. 
It shall be free from vegetable or other deleterious matter, and 
shall contain no soft, thin, or elongated pieces. 
The gravel aggregate, when tested by means of laboratory 
screens, shall meet the following requirements : 
Per cent. 
Passing .^.^..^^e^^ize selected) inch screen. 100 
Passing |^. e ..^^est..size ; selected) i nc h scree n 
and retained on (the second largest size 
selected) j ncn screen to 
Passing (the second largest size selected) inch 
screen and retained on .(the third largest 
s !. z ®. .® e .! e . c . t . e ! i . ) .. incn screen to 
tPassing, etc 
The gravel shall be sampled for quality and grading in accord- 
ance with the method described on page , paragraphs , 
of these specifications; and the grading shall be determined in 
accordance with the method described or referred to on page 
of these specifications, test No. 
SPECIFICATION FOR GRAVEL FOR COARSE AGGREGATE FOR PORTLAND-CEMENT 
CONCRETE WEARING SURFACE. 
Grading. 
Methods of 
sampl ing and 
grading. 
The gravel aggregate shall consist of sound, hard, durable rock 
of high resistance to abrasion,* and shall contain no particles of 
shale, slate, coal, or other materials which easily disintegrate. It 
shall be free from vegetable or other deleterious matter, and shall 
contain no soft, thin, or elongated pieces. 
* The conference believes it highly desirable to specify definite test 
limits for the resistance of gravel to abrasion. The only State which 
has so far extensively employed an abrasion test for gravel is Ohio. 
Available test records, therefore, cover only gravels used in that State, 
and it is felt that sufficient data have not been obtained as yet to war- 
rant the use of an abrasion-test clause in the gravel specifications of 
other States. The conference recommends that individual States make 
use of the Ohio test for the purpose of establishing limits which may 
be used later in specifying satisfactory gravels which are available for 
their highway work. A description of this test will be found on page 30. 
t The number and sizes of screens and sieves may be continued as 
desired by the engineer. For 10-mesh sieve and finer, the wording should 
be: Passing mesh sieve and retained on mesh sieve, 
to The last requirement should be : Passing inch screen 
(or mesh sieve) not more than (or not less than) „. 
88979°— 17— Bull. 555 3 
General. 
