134 



The Philippine Journal of Science 



1914 



All commercial cements season more or less during the process 

 of manufacture. The cements under consideration required no 

 seasoning, but it was thought advisable to aerate * them in the 

 laboratory for twenty-one hours spread out in layers about 2.5 

 centimeters in thickness, after which they were subjected to 

 all specified tests. The results obtained, together with the 

 requirements of the standard specifications now in operation, are 

 given in Table IV, 



Table IV.— Physical properties of the Portland cements obtained from the 



first four mixtures.^ 



Test. 



No. 1. 



No. 2. 



98.9 



98 



78 



78.6 



3.16 



3.15 



20 



21 



sound 



sound 



2.8 



3.3 



5.5 



4.8 



507 



404 



860 



740 



840 



780 



315 



298 



410 



360 



No. 3. 



No. 4. 



Specified 

 require- 

 ments. 



Fineness: 



Per cent through the lOO-mesh sieve 



Per cent through the 200-mesh sieve 



Specific gravity (dried at 110°C.) 



Water required for normal consistency 



Soundness, air, water, and steam 



Time of setting in hours: 



Initial set 



Final set 



Tensile strength in pounds per square inch: 



1-day, neat mortar 



7-day, neat mortar 



28-day, neat mortar 



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



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



98.4 

 78.8 

 3.16 

 20 

 sound 



0.9 

 2 



870 

 520 

 605 

 258 

 320 



98.2 

 78.4 

 3.16 

 20 

 sound 



3.2 

 4.6 



420 

 755 

 780 

 275 

 360 



92 



75 

 3.1 

 none 

 sound 



(b) 

 (<^) 



none 



500 



600 



200 



275 



PRINCIPAL CONSTITUENTS OF THE NONPLASTERED CEMENTS (BY ANALYSES). 



Silica (SiOa) __ 



Alumina (AI2O3) and ferric oxide (Fe203) - 



Calcium oxide (CaO) 



Magnesia (MgO) 



Hydraulic modulus 



22.65 



10.70 



64.70 



1.60 



1.98 



23.95 

 7.54 



65.35 

 1.16 

 2.11 



23.80 

 9.65 



62.60 

 1.44 

 L86 



23.10 



10.07 



63.95 



1.33 



1.97 



(d) 



' Content of plaster = 2 per cent. 



•> Not less than 0.75. 



<= Within 10. 



'' Less than 4. 



Each of the cements passed well above all of the requirements, 

 optional or otherwise, of the United States Government specifica- 

 tions for Portland cement as adopted by the Government of 

 the Philippine Islands. They also pass the requirements of the 

 present cement specification of the American Society for Testing 

 Materials. The good results obtained from mixture 2 are of 



* We regard aeration as the least efficient, practical method of seasoning 

 Portland cement, and recommend grinding in the presence of steam or, 

 better, quenching the hot clinker thoroughly with, or in, water. 



