PORTLAND CEMENT TESTING. 



By W. C. Reibung and L. A. Salingee. 

 {From the Ghemical Laboratory, Bureau of Science, Manila, P. I.) 



IN'TEODTJCTION. 



This pajjer is devoted to a discussion of modern cement specifications 

 and we have endeavored to point out many reasons why they do not 

 exclude the personal error that is experienced by all testers working under 

 them. Simple methods and precautions necessary to reduce this varia- 

 tion have been suggested. Throughout the discussion, the effects of the 

 requirements of cement specifieationSj the difference possible in manipula- 

 tion and the consequent variations in the results obtained have been il- 

 lustrated. Certain powerful climatic influences that tropical conditions 

 may exert upon cement are also discussed, and the last chapter suggests 

 the characteristics which a cement should have to give the 'greatest 

 efficiency under tropical influences. 



SPECIFICATIONS. 



The "value of standard specifications to the engineer, the consumer, 

 and the country at large is as great as tlieir value to the manufacturer. 

 A standard specification, provided it is both equitable and safe, cheapens 

 the product, insures quicker deliveries and acts as a powerful regulator 

 to the industries affected. * * * y/jg danger of a fixed standard of 

 any Mnd lies in its iecoming unprogressive and folloiving behind the 

 demands of the time."^ 



The last sentence should be especially emphasized. All official cement 

 testing in the Philippines at present is done under the United States 

 Army Engineer Specifications of 1902. jSTo change has been made in 

 these specifications in the last six years despite the great amount of work 

 which has been done upon the physical and chemical properties of 

 Portland cement in recent times, and, in the light of experience, it has 

 been found that these specifications could certainly be improved. This 

 unprogressive tendency is, perhaps, due to the inertia inherent in all 

 committee work. Each individual member has fixed ideas on certain 

 questions, or on the results of certain personal experiences. As one writer 



1 Editorial: Eng. Neios (1904), 51, 612, (Italics supplied.) 



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