PHILIPPINE RAW CEMENT MATERIALS.' 



By Alvin J. Cox.. 

 {From the Laboratory of Inorganic and Physical Chemistry, Bureau of Science, 



Manila, P. I.) 



The essential constituents of Portland cement are calcium oxide 

 (CaO); silica (SiOj), and alumina (ALOj) or some other flux such as 

 ferric oxide whichj similarily to alumina is able to promote the union of 

 silica and lime. Calcium oxide does not occur in nature in the free 

 state, but in combination as calcium carbonate (limestone^ chalk, etc.). 

 Silica and alumina are found in the form of minerals such as quartz 

 and corundum, but in tliis form the}' are not suitable for the manufacture 

 of cement, owing to the difficulty of grinding the materials to a 

 sufficiently fine state to cause them to comljine . -with lime; thereto I'e, 

 combinations of these two oxides occurring as silicates of alumina, 

 termed clay or shale, are the chief source of these constituents in the raw 

 materials used in cement -manufacture. The majority of limestones 

 contain some clay, and clays often contain a certain amount of limestone, 

 these facts are taken into account in proportioning the raw materials. 



EAW CEMEJ^T MjrVTERIALS ON THE ISLAND OF BATAN. 



Limestone occurs abundantly on nearly every Island of the Philippine 

 Archipelago and in this region is uniforniily remarkably jjure. On 

 the other hand, suitable shale or clay for the manufacture of a high 

 grade Portland cement is more difficult to obtain. It will be seen by 

 referring to any of the military records of drill holes made when pros- 

 pecting for coal on Batan Island with a standard diamond 2-inch core 

 drill, that the holes penetrate thick layers of grayish-blue shale separated 

 by more or less thin layers of fossil or calcareous shale and limestone. 

 It was thought that analyses of these blue shales might show the 

 variation to be expected, reveal tlie pi'esence of some materials not 

 otherwise easily accessible and that they would help to form an opinion 

 as to what, if anj^, siliceous cement materials exist on this island. The 

 beds encountered are not horizontal; the dip indicates that they outcrop 

 somewhere on the island. If these are suitable for the purjjose of cement 



' The first discussion of this subject was published in This Journal, Sec. A. 

 (1908), 3, 391. 



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