IX, A, 2 Reibling and Reyes: Portland Cement Materials 147 



raw materials are capable of producing natural cement with a 

 cementation index as high as 2.47 and still pass the require- 

 ments of specifications in spite of the fact that such products 

 become feebler as this index rises above 2. . 



Table XIV.- — Characteristics of artificial Roman cement "I" obtained from 



Nag a raiv materials. 



MIXTURE BURNED AT 1,000° C. 



Material. 



Corallin e limestone 



Clay 51 



Mixture 



Per cent 



Parts 



by 



weight. 



100 

 100 

 200 

 100 



Si02. 



9.34 

 41.97 

 51.31 

 25.65 



R2O3. 



2.94 

 18.20 

 21.14 

 10.57 



CaO. 



47.38 

 15.12 

 62.50 

 31.25 



MgO. 



Loss by 

 igni- 

 tion. 



0.89 

 2.16 

 3.05 

 1.52 



35.90 

 19.45 

 55.35 

 27.68 



Cemen. 

 tation 

 index. 



a 2. 47 



CEMENT. 



Test. 



Result. 



Require- 

 ment of 



specifica- 

 tions, b 



Time of setting: 



Initial set in minutes 



Final set in hours 



Tensile strength in pounds per square inch: 



Neat mortar, 7 days__ 



Neat mortar, 28 days 



Neat mortar, 3 months 



7-day, 1 :3, Ottawa-sand mortar 



28-day, 1 : 3, Ottawa-sand mortar 



3-month, 1 : 3, Ottawa-sand mortar 



30 

 3 



167 

 262 

 300 

 148 

 330 

 385 



(d) 



150 

 250 



50 

 125 



(e) 



2.8 X %Si02 + 1.1 X yoAlgOs + ■^ X %Fe203 

 %Ca0 + 1.4 X %Mg0 

 ''Am. Soc. Test. Materials (1912). 



<= Not less than 10. 

 ^ Not more than 3. 

 " Not given. 



CONCLUSION 



The results obtained by this investigation are regarded as 

 conclusive proof of the following: 



1. The raw materials which are available in the vicinity of 

 Naga, Cebu, are eminently suitable for .the commercial manufac- 

 ture of high-grade Portland cement.'" 



" Plate II, figs. 1 and 2, are photographs of raw materials from Naga, 

 Cebu, and samples of Portland and Roman cement and concrete which they 

 produced. These products formed part of the exhibit of the Bureau of 

 Science of local calcareous-siliceous resources at the 1914 Philippine Expo- 

 sition. 



