PHYSICAL PROPERTIES OF PORTLAND CEMENT. 



585 



TABLE 222. 

 FINENESS OF VARIOUS AMERICAN PORTLANDS. (BLEININGER.) 



Specific gravity. The specific gravity of a Portland cement is a 

 property which is of no importance of itself to the engineer. The 

 reason for determining it is in order to rule out underburned or adul- 



300 



200 



1.00 



TEN 



ION 



'3000 



W 



2000 



1000 



7 



COMPR 



10 15 20 25 30 

 FIG. 144.* Effect on strength of regrinding cement. (Tetmajer.) 



J.O 15 20 25 5 



AGE IN DAYS 



terated cement. The specific gravity of a well-dried sample of Port- 

 land cement will rarely fall below 3.10; while that of a natural cement, 

 a slag cement, or a Portland adulterated with slag will rarely rise above 



* From Johnson's " Materials of Construction ", p. 411. 



