CEMENT 67 



(h) Cement failing to meet the 7-day requirements may be 

 held awaiting the results of the 28-day tests before 

 rejection. 



(i) All tests shall be made in accordance with the methods 

 proposed by the Committee on Uniform Tests of Cement 

 of the American Society of Civil Engineers, presented 

 to the Society, January 21, 1903, and amended January 

 20, 1904, and January 15, 1908, with all subsequent 

 amendments thereto. 



(/) The acceptance or rejection shall be based on the following 

 requirements:. (Pars. 295 to 306.) 



NATURAL CEMENT 



295. Definition. This term shall be applied to the finely 

 pulverized product resulting from the calcination of an argil- 

 laceous limestone at a temperature only sufficient to drive off the 

 carbonic acid gas. 



296. Fineness. It shall leave by weight a residue of not 

 more than 10 per cent on the No. 100, and 30 per cent on the No. 

 200 sieve. 



297. Time of Setting. It shall not develop initial set in less 

 than 10 minutes, and shall not develop hard set in less than 

 30 minutes, or in more than 3 hours. 



298. Tensile Strength. The minimum requirements for ten- 

 sile strength for briquettes 1 in. square in cross-section shall be 

 as follows, and the cement shall show no retrogression in 

 strength within the periods specified: 



NEAT CEMENT 

 Age. Strength. 



24 hours in moist air 75 Ibs. 



7 days (1 day in moist air, 6 days in water) 150 " 



28 days (1 27 " " ) 250 " 



ONE PART CEMENT, THREE PARTS STANDARD OTTAWA SAND 



7 days (1 day in moist air, 6 days in water) 50 Ibs. 



28 days (1 27 " " ) 125 " 



If the minimum strength is not specified, the mean of the above 

 values shall be taken as the minimum strength required. 



299. Constancy of Volume. Pats of neat cement about 3-in. 



