IX, A, 2 



Reibling and Reyes: Portland Cement Materials 141 



cements 1, 2, 4, la, and 3a. Cement 3 became quick setting, but 

 as is shown by the data in Table X its quick-setting properties 

 were easily remedied by either a little additional seasoning or 

 plaster. 



Cement 2a became extremely quick setting, but as already 

 stated its setting properties were not satisfactory when it had 

 been pulverized only to an ordinary degree of fineness. 



AUTOCLAVE TESTS 



It is not thought probable that an autoclave test such as is 

 described in the "specifications for Portland cement" of the 

 Delaware, Lackawanna and Western Railroad Company will be 

 adopted by the United States Government or by the American 

 Society for Testing Materials. However, the data in Table 

 XI make it evident that these raw materials are capable of 

 producing Portland cement which will pass even such severe 

 requirements. 



Table XL — Autoclave tests '' of cements 



' 1, 2, 



i., and 5. 









Results obtained. 



Test. 



Requirements of the D., L. 

 and W. R. R. Co. 





No. 1. 



No. 2. 



No. 4. 



1 

 No. 5. 



Tensile strength in pounds per 













square inch: 













Neat mortar after 24 hours in 



Not less than 200 



507 



404 



420 



505 



moist air. 













Neat mortar after autoclave 

 test. 



Not less than 500 



580 



700 



596 



573 





Expansion of neat mortar in per 



Not greater than 0. 5 



0.127 



0.104 



0.160 



0.052 



cent. 











" Steam pressure := 295 pounds per square inch. 



^ Not reground. The fineness is recorded in Tables III and V. 



RELATIVE MERITS OF AVAILABLE RAW MATERIALS 



Other conditions being the same, the suitability of a lime- 

 stone for the manufacture of good Portland cement increases as 

 its chemical composition approaches that of the cement clinker. 

 "Cement rock," which requires little or no additional calcareous 

 or siliceous material, is ideal in this respect, as nature already 

 has prepared a more or less intimately mixed and partially com- 

 bined mixture which must be produced by artificial means when 

 the limestone is purer. Furthermore, the particles of com- 

 paratively pure limestone which fail to combine with siliceous 



