662 



CEMENTS, LIMES, AND PLASTERS. 



The slag-cement plant at Konigshof,* Germany, utilizes slag from 

 the Carl-Emil furnaces. A typical analysis of this slag shows : 



Per Cent. 



A1 2 O 3 18.71 



FeO 1 .80 



CaO 49.16 



MgO 2.45 



The more important constituents commonly vary between the 

 following limits: 



Per Cent. 



SiO 2 24 to 27 



A1 2 O 3 17 " 19 



CaO. 49 " 54 



The slag is granulated, dried, and ground to such fineness that all 

 passes a sieve with 900 meshes per square centimeter, and 85 per cent 

 passes a sieve of 5000 meshes per square centimeter. 



The limestone is obtained from quarries at Koneprus, and is burned 

 in continuous shaft kilns. Analysis of the resulting lime shows: 



Per Cent. 



Si0 2 12.421 



A1 2 O 3 2.620 



Fe 2 3 0.883 



CaO 81 .546 



MgO 1 . 751 



Moisture 0.425 



From this analysis it would seem probable that the lime is iteelf 

 somewhat hydraulic. It is carefully slaked, and stored until the slaking 

 is complete, after which it is screened to remove the coarser particles. 



The slag and lime are then mixed and ground together in propor- 

 tions giving a cement of the following typical composition: 



Per Cent. 



SiO 2 . 20 . 81 



A1 2 6 3 10.50 



Fe 2 O 3 1 .90 



CaO 55.90 



MgO 1.41 



S 0.58 



S0 3 0.91 



Loss on ignition 3 . 50 



* Jour. Iron and Steel Inst., vol. 2, 1900, p. 508. 



