PHYSICAL PROPERTIES OF PORTLAND CEMENT. 



593 



tion with the cement in any way, for ground limestone will give as good 

 results as ground quartz. 



450 



150 200 



AGE IN DAYS 



300 



350 



FIG. 150.* Strength of sand-cement mortar. The first figure on each curve de- 

 notes parts of Portland cement; the second, parts of ground sand; the third, 

 parts of unground sand. 



The tests quoted in Table 227 were made at Albany in the labora- 

 tory of the State Engineer. Iron Clad is a Portland cement of high 

 grade, while Victor is the sand cement made from it by grinding Iron 

 Clad with limestone. 



* From Johnson's "Materials of Construction", p. 579. 



