

SLAG CEMENT. REQUISITES AND TREATMENT OF THE SLAG. 647 



the case of granulated slags, it is cooled with great suddenness, it becomes 

 an important hydraulic agent. When so cooled "it is attackable by 

 weak acids and also by alkalies. It combines particularly with hyd rated 

 lime in setting, and gives rise to silicates and aluminates of lime iden- 

 tical with those which are formed by entirely different reactions during 

 the setting of Portland cement. It is upon this property that the manu- 



AGE IN DAVS 



COMPRESSION 

 FIG. 159.* Effect of granulating slag. 



(Tetmajer.) 



70 



280 



350 



140 210 



AGE IN DA.YS 



TENSION 

 FIG. 160.* Effect of granulating slag. (Tetmajer.) 



facture of slag cements, which assumes daily greater importance, is 

 based ". 



Increased hydraulicity due to granulation. The striking increase in 

 the hydraulic properties of the slag when it is granulated was well 

 brought out by Frost's investigations. The following table (244), giving 

 the results of tests of tensile and compressive strength of briquettes of 



* From Johnson's " Materials of Construction", p. 190. 



