126 



Table 72 

 MECHANICAL PROPERTIES 



Cement and Concrete 



(a) Cement 



Cement: Specification Values (A. S. T. M. Co. to 17, Cio to 09, and Co to 16T). 



Minimum strengths based on tests of 645 mm 2 (1 in 2 ) cross section briquettes for tension, 

 and cylinders 50.8 mm (2 in.) diameter by 101.6 mm (4 in.) length for compression. Mortar, 

 composed of 1 part cement to 3 parts Ottawa sand by volume; specimens kept in damp 

 closet for first 24 hours and in water from then on until tested. 



(b) Cement and Cement Mortars 



Cement and Cement Mortars. — Bureau of Standards Experimental Values. Com- 

 pressive Strengths of Portland cement mortars of uniform plastic consistency. Data from 

 tests on 50.8 mm (2 in.) cubes stored in water. Sand: Potomac River, representative con- 

 crete sand. 



Cement. 



Sand. 



Proportions by volume. 



Water, 

 per cent. 



30.O 

 16.O 

 13.6 

 13-9 

 151 



days. 



7 

 28 



7 

 28 



7 

 28 



7 

 28 



7 



Compressive strength. 



kg/mm 2 



4. 20 

 6.40 

 3 IO 

 4-75 

 2.05 

 3 10 

 1 25 

 2.05 

 o. 10 

 0.1S 



lb/in 2 



5.970 

 9,120 

 4,44° 

 6,750 

 2,900 

 4,440 

 1,780 

 2,890 

 I20 

 200 



Note. — (From Bureau of Standards Tech. Paper 58.) Neat cement briquettes mixed at 

 plastic consistency (water 21 per cent) show 0.52 kg/mm 2 or 740 lb/in 2 tensile strength at 28 

 days' age; 



1 Cement: 3 Ottawa sand-mortar briquettes, mixed at plastic consistency (water 9 per 

 cent) show 0.28 kg/mm 2 or 400 lb/in 2 tensile strength at 28 days' age. 



Smithsonian Tables. 



