SLAG CEMENTS: COMPOSITION AND PROPERTIES. 



667 



it may be of value, not only to engineers and slag-cement manufacturers, 

 but to commercial chemists, to state in some detail what substances 

 are to be expected in examining a normal slag cement. Slag cement, 

 when ready for sale, is a mechanical mixture of slaked lime and slag. 

 The slaked lime is lime hydrate [Ca 2 (OH) 2 ]; the slag may be regarded 

 as a calcium aluminum silicate (z.CaO, t/.Al 2 3 .Si02) . In addition 

 to the essential ingredients lime, silica, alumina, and water con- 

 tained in these two components of the cement, certain other constitu- 

 ents may occur in small but often interesting percentages. Of these 

 sulphur, iron, magnesia, carbon dioxide, fluorine and soda are those 

 most commonly found. 



Analyses of a number of American slag cements are presented in 

 the following table. The Cementation Index of several of these has 

 been calculated, and it will be seen that it gives values (1.59, 1.67, 1.72, 

 1.87) far above those given by any modern Portland cement: 



TABLE 249. 



ANALYSES OF AMERICAN SLAG CEMENTS. 



1. "Southern Cross Portland 



2. "Steel Puzzolan". Illinois Steel Co., Chicago, 111. 



circular. 

 3-6. "Steel Puzzolan". Illinois Steel Co., Chicago, 111 



Birmingham Cement Co., Ensley, Ala. Private communi- 

 Lathury & Spackman, anal. Mfrs. 



-6. "Steel Puzzolan". Illinois Steel Co., Chicago, 111. 



7. Maryland Cement Co., Sparrows Pt., Md. Cement Directory, 2d ed., p. 207. 



8. " " " " " . " Private communication. 



10-12. 



'Brier Hill Portland 1 



tion. 

 'Stewart Portland". 



Brier Hill Coal & Iron Co., Brier Hill, Ohio. Private communica- 

 Stewart Portland Cement Co., Sharon, Pa. Private communication. 



