96 



The Philippine Journal of Science 



1914 



with 2.61 parts of pure limestone (12.06 per cent less than 

 required by the formula) were prepared. Next, these two 

 mixtures were combined in the proportion of 2 parts of tuff to 

 1 part of clay. Table XIV gives calculations of the combined 

 raw mixture. 



Table XIV. — Calculation of comhhied mixture of Danao clay and 



volcanic tuff. 





Total. 



Individual constituents. 



Silica 



(Si02). 



Alumina Ironoxide Lime 

 (AI2O3). (Fe203). (CaO). 



Magnesia V°'^«'« 

 (MgO). ^^°tc!). ' 



Figures represent parts of the material by weight. 



TuflE mixture 



198.98 j 31.22 

 100.15 15.23 



10.82 

 5.41 



3.86 83 38 94 kr 7R 





2.05 41.75 40.51 



35.20 



Unburned _. 



Volatile .__. 



299.13 

 103.96 



46.45 



16.23 



5. 91 125. 13 1 1. 45 



1 



103.96 



Burned 







i 





195. 17 



46.45 



16.23 



5.91 125.13 L45 









Calculated composition in percentage. 



1 





99.98 15.53 5.43 

 99.92 2.<{.8n 8.^1 



1.98 

 3.03 



41.79 

 64.04 



0.48 

 0.74 



34.77 



Clinker 













The silica to alumina (plus iron oxide) ratio in the mixture is 2.10. 

 The lime to silica, alumina, and iron oxide ratio in the mixture is 1.82. 

 Cementation index of the mixture is 1.20. 



The ground clinker from the burned mixture gave the following 

 results : 



Table XV. — Physical examination of cement from Dana^o clay and volcanic 



tuff combination. 



Specific 

 gravity. 



Soundness and set. 



Tensile strength in pounds per square 

 inch. 



Soundness. 



Initial set. 



Final set. 



Neat cement. 



1 cement : 3 sand. 



5 hours. 



28 days. 



7 days. 



28 days. 



7 days. 



28 days. 



3.28 



Sound 



Sound 



Hrs. mins. 

 2 30 



Hrs. mins. 

 8 50 



510 



640 



239 



309 



