FORMS FOE SPECIFICATIONS, ETC., FOE ROAD MATEEIALS. 



21 



It shall be well graded from coarse to fine and, when tested 

 by means of laboratory screens, shall meet the following re- 

 quirements : 



Per cent. 



Passing * mesh sieve not less than f 



Passing 100-mesh sieve not more than 



Not more than per cent by weight shall be removed by 



the elutriation test. 



When the sand is mixed with Portland cement in the propor- 

 tions of 1 part of cement to 3 parts of sand by weight, according 

 to standard methods of making 1 :3 mortar briquets, the resulting 

 mortar at the age of 7 and 28 days shall have a tensile strength 



of at least t per cent of that developed in the same time 



by mortar of the same proportions and consistency, made of the 

 same cement and Ottawa sand. 



Preliminary acceptance samples shall be subjected to both 7 

 and 28 day tests, and acceptance based thereupon. Samples tested 

 during the progress of the work will be accepted on the basis of 

 the 7-day test. 



The sand shall be sampled in accordance with the method de- 

 scribed on page , paragraphs , of these specifications ; 



and the grading shall be determined in accordance with the 

 methods described, or referred to, on page of these speci- 

 fications, tests Nos. 



Grading. 



M o r t a 

 strength test. 



Methods of 



sampl i n g and 

 grading. 



Note. — It is recommended that volumetric analyses be reported 

 by the laboratory to facilitate field control. 



SPECIFICATION FOR SAND FOR CUSHION. 



The sand shall pass a inch laboratory screen, and not 



less than per cent shall pass a 20-mesh sieve. The ma- 

 terial removed by the elutriation test, consisting chiefly of clay 

 and loam, shall not exceed -- per cent by weight. 



The sand shall be sampled in accordance with the method de- 

 scribed on page , paragraphs , of these specifications ; 



and the grading shall be determined in accordance with the 

 methods described, or referred to, on pages of these speci- 

 fications, tests Nos. 



Grading. 



Methods of 

 sampl i n g and 

 testing. 



Note. — It is recommended that volumetric analyses be reported 

 by the laboratory to facilitate field control. 



SPECIFICATION FOR MINERAL FILLER. 



The mineral filler shall consist of ^^^AyP^^pwable) 



It shall be free from foreign or other objectionable material and 

 when tested by means of laboratory sieves shall meet the follow- 

 ing requirements : Per cent. 



Passing -mesh sieve 100 



Passing -mesh sieve not less than 



General. 



* It is recommended that a 10-mesh sieve be specified. 



t Ninety-five per cent is recommended for this purpose. 



X It is recommended that 65 per cent be the minimum allowable 

 strength ratio, and that in localities where practicable a higher strength 

 ratio be specified. 



