IX, A, 1 



West and Cox: Philippine Cement Raw Materials 93 



Table VIII. — Ultimate analysis of volcanic tuff. 

 Constituent. Per cent. 



Silica (SiOa) "56.36 



Alumina (AUO.) 19.53 



Ferric oxide (Fe^Oa) 6.97 



Lime (CaO) 4.31 



Magnesia (MgO) 1.70 



Alkalies (NaoO + KsO) 1.99 



Volatile matter ' 9.30 



100.16 



Total 



' Soluble silicates =: 18.60 per cent. 



The relatively large percentage of soluble silicates is a de- 

 sirable feature. A rational analysis indicated the presence of 

 about 5 per cent of free silica. It is probable that the result 

 gives an erroneous impression for materials of this class and 

 that there is only a very small amount of free silica actually 

 present.-" 



A mixture prepared according to the method of calculation 

 from the formula described under^the discussion of Danao clay 

 would consist of 1 part of tuff combined with 2.968 parts of pure 

 limestone. Two mixtures containing 2 and 5 per cent less lime- 

 stone, respectively, were prepared. The calculations of these 

 are given in Tables IX and XI, respectively. 



Table IX. — Calculation of volcanic tuff raw mixture containing 2.29 per 

 cent less pure limestone than required by the formula. 





Total. 



Individual constituents. 



Silica 



(Si02). 



Alumina Iron oxide 

 (AI2O3). (Fe203). 



Lime MagnesiaLpYP'^Ji'l 

 (CaO). (MgO). ''^°|-<.jf^' 



Figrures represent parts of the material by weight. 



Limestone 



209. 00 

 100.00 









162.40 

 4.30 





127.60 

 9.30 



Tuff 



56.36 



19.53 



6.97 



1.70 



Unburned 



Volatile 



390.00 

 136.90 



56.36 



19.53 



6.97 



166.70 



L70 



136.90 

















251. 10 



56.36 



19.53 



6.97 



166.70 



1.70 









Calculated composition in percentage. 



Mixture 



Clinker 



99.52 

 99.27 



14.45 

 22.27 



5.01 

 7.72 



1.79 

 2.75 



42.74 

 65.86 



0.43 

 0.67 



1 

 36.10 







The silica to alumina (plus iron oxide) ratio in the mixture is 2.13. 

 The lime to silica, alumina, and iron oxide ratio in the mixture is 2.01. 

 Cementation index of the mixture is 1.09. 



'"'Cf. footnote 7. 



