PHYSICAL PROPERTIES OF PORTLAND CEMENT. 



589 



work. Compressive tests, however, require the use of heavy testing 

 machines, and are therefore not adapted for field or ordinary office tests. 

 (See Tables 223 and 224.) 



800 



$600 



2 



200 



A 



I 



vy 



2 4 6 8 10 



PROPORTIONS OF ANO TO 1 CEMENT 



FIG. 148.* Effect of character of sand on tensile strength. 



TABLE 223. 

 COMPRESSIVE STRENGTH OF PORTLAND-CEMENT CUBES, WATERTOWN ARSENAL. 



Report on Tests of Metals, etc., at Watertown Arsenal, 1902, pp. 369-376. 



Ratio of compressive to tensile strength. For a given age and 

 mixture, the ratio between the compressive and tensile strength of a 

 Portland-cement mortar is practically fixed. The ratio increases with 

 increasing age, and also increases with increasing proportions of sand. 



*From Johnson's " Materials of Construction", p. 581. 



