IX, A, 2 



Reibling: Natural Cement versus Brick 



169 



deleterious constituents are not present in sufficient quantities 

 to cause any undesirable effects. In short, the sand is a very- 

 efficient calcareous raw material for the manufacture of either 

 Roman or Portland cement. However, because the Iwahig clay 

 is too low in silica and too high in alumina and iron oxide to 

 produce a mixture which will meet the requirements of the 

 Portland cement industry, the only commercially feasible plan 

 for utilizing this sand is the manufacture of a natural cement. 



The data in Table V show the composition of the four natural 

 cement mixtures which were prepared for burning. In each 

 instance, the sand and clay were thoroughly dried and then 

 pulverized until 98 per cent passed through the 100-mesh sieve. 



Table V. — The composition of the four natural cement mixtures prepared 



from Iwahig clay and sand. 



Material. 



wei'^ht'' Chemical constituents in per cent. 



Cemen- 

 tation 

 index. " 



Sand. 

 



\ 



7 



7 



12 



Clay. 



Si02. 



AI2O3. 



FezOa. 



CaO. 



MgO. 



Iwahig clav ^j_ 



1 

 

 1 

 4 

 5 

 5 



42.16 



1.18 

 14.84 

 16.08 

 19.01 

 1.<!.23 



24.26 



I.q 90 



6.40 

 48.00 

 34.13 

 32.87 

 30.66 

 35.76 



0.94 

 2.46 

 1 95 



1 i7 



Iwahig sand _ 



Mixture 1 



0. 68 0. 40 

 8. 54 4. 90 

 9 25 5 31 



Mixture 2 



1. 91 1. 69 

 1. 90 2. 12 

 2.01 1.24 





10.51 

 7.61 



6.03 

 4.37 









^2.8X 



%Si02 H 



%Ca 



h 1.1 X 

 + 1 



Al,03 + 



4 X %M 



0.7 X P 

 gO 



jBaOa 









These mixtures were each pugged with water to the con- 

 sistency of stiff mud, molded into 9-inch bricks, and when 

 dry burned at a temperature of about 1,000 °C, in an experimental 

 brick kiln. The resulting clinkers disintegrated more or less 

 when exposed to the air for several days, and when moistened 

 with water crumbled to pieces within twenty-four hours. This 

 fact and the microscopic phenolate test described elsewhere ^ 

 showed that considerable free lime was present. However, the 

 free lime was not sintered, and therefore it slaked as soon 

 as exposed to water. On the other hand, as the burned bricks 

 contained no carbon dioxide, the raw materials had been 

 thoroughly calcined. 



Mixture 3 slaked the least and 4 the most. In all probability, 

 better results would have been obtained by burning the mixtures 



'White, Alfred H., Journ. hid. & Eng. Chem. (1909), 1, 5; Reibling, 

 W. C, and Reyes, F. D., This Journal, Sec. A (1910), 5, 367-419. 



126870 5 



