142 The Philippine Journal of Science i9n 



Table V. — Effect of sodium carbonate on the setting time of cements. 



Brand. 



O 

 ra 



0) 



■o 

 •E 

 •o 



J3 

 C 



3 



£ 

 "3 



Concentration of solutions. 



4 grams per liter. 



10 grams per liter. 



20 grams per liter. 



40 grams per liter. 



■ J 



»| 



e J 

 SJ « 

 3 u 



8*8 



o | 



si 



Is 

 > 



Time of 



setting. 



|| 

 > 



Time of 

 setting. 



»c 



§1 



1| 



'o I 



o S 



£ 3 



II 

 > 



Time of 

 setting. 



.2 £ 



lb 

 oi 



|s 



Time of 



setting. 



"c 



i 



£ 



c 



c 



E 



c 



c 

 E 



'£ 



"3 



E 



A 



B 



C 



D__ 



E 



Fl 



F2 



F3 



0.67 

 0.86 

 1.34 

 1.34 

 1.24 

 1.50 

 1.20 

 1.41 



cc. 

 24 

 23 

 25 

 23 

 23 

 22 

 26 

 25 



H. to. 



5 20 



6 50 

 5 45 



3 50 

 5 45 

 2 10 

 5 5 



4 55 



H. to. 



9 25 

 9 50 

 9 50 

 5 55 

 8 15 

 5 45 

 8 

 7 55 



cc. 

 24 



25 

 23 



23 

 22 

 26 

 25 



tf. m. 



5 40 

 5 35 

 5 30 

 3 5 



3 40 

 2 5 



4 10 

 4 



H. TO. 



9 

 9 

 9 25 



6 5 



7 50 

 5 35 

 7 50 

 7 50 



cc. 



2! 

 23 

 25 

 23 

 23 

 22 

 26 

 26 



H. TO. 



4 20 



5 25 

 5 

 1 50 

 4 

 1 50 

 4 5 

 4 



fl. TO. 



8 40 

 8 25 

 8 40 

 5 

 7 30 



5 20 

 7 30 



6 55 



cc. 

 24 

 23 

 25 

 23 

 23 

 22 

 26 

 26 



H. m. 



4 15 



5 

 4 45 



1 



2 45 



2 15 



3 10 

 3 



H. TO. 



7 45 



8 15 

 8 15 



4 20 



5 30 



6 15 



7 15 

 7 20 



The following statements concerning the quantity of sulphuric 

 anhydride in cement are based on the cements studied in this 

 laboratory for periods 1S up to ninety days : 



1. The maximum retardation of set is produced by 1.5 per 

 cent to 2 per cent. 



2. In general, the briquettes show a decrease in strength when 

 the cement contains more than 2 per cent, except in brands 

 E and F, which decrease in strength only when the content 

 amounts to about 5 per cent. 



3. The soundness (five hours in steam) is unaffected by any 

 amount investigated. 



4. The percentage loss in tensile strength is greater with the 

 mortar than with the neat briquettes. 



18 Measurements of expansion bars are being made over a period of 

 months, and briquettes for long-time tensile-strength tests are being 

 matured. Those that have been since completed indicate no well-defined 

 relation between tensile strength and sulphuric anhydride content, but show 

 that, in general, the maximum strength of the mortar briquettes corresponds 

 to a higher percentage of this compound than in the series discussed in 

 this paper. With most of the cements investigated, sulphuric anhydride, 

 in quantities less than 3 per cent, caused no serious expansion in sea water. 



