

FORMS FOE SPECIFICATIONS, ETC., FOE EOAD MATEEIALS. 17 



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- Methods of 

 cordance with the method described on page , paragraphs sampling and 



10 ' * ° L testing. 



, 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 Grading. 



screens, shall meet the following requirements : 



Per cent. 

 Passing .l t . h . e . 1 ^ r S e . s . t .. s i. z e.selected) iDch screen _ 100 



Passing l^krgrat size selected ) inch screen 

 and retained on (the second largest size 



selected) inch screen to 



Passing (the second largest size selected) inch 

 screen and retained on .<. th . e ... th f. rd ... lar .s e . s .t 



8i . z . e .. . s . el . e . ct . e $). incn screen to 



tPassing, etc . 



The gravel shall be sampled for quality and grading in accord- Methods of 



■ii. li. «. j j -u j v. sampling and 



ance with the method described on page , paragraphs , grading. 



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. 



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 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 shou-ld 



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 



