XI, A, 6 



Witt: The Effect of Sulphide on Cement 



283 



Table VIII. — An example of variation in percentage loss in tensile strength 

 with concentration of sulphide. 



Solution No. 



Water only, 



4 



3 



2 



1 



Sulphide 

 per liter. 



Tensile strength." 



Loss in 

 I tensile 



Per square; Per square strength, 

 centimeter. inch. 



Grams. 



0.097 

 0.97 

 4.80 

 9.70 



Kilos. 

 41.8 

 4L2 

 35.4 

 2L1 

 18.9 



Pounds. 

 595 

 586 

 506 

 300 

 268 



Kilos. 



0.6 



6.4 



20.7 



22.9 



Percentage 

 loss. 



1.43 

 15.31 



49.52 

 54.78 



* All briquettes were made of neat cement (brand A) and broken at the end of seven days. 



The variation in percentage loss in tensile strength is also 

 shown in fig. 1. 



Concentration of sodium sulphid 

 / 2 3 



B solutions in 

 •f 



grams per liter (applicable to 



5 6 7a 



curve B) 



3 



■ 











































^ 



SO 































— - 





" 















^ 









f^ 



.'^ 











""~~ 









■OA 





















/ 



/' 







































/ 































30 











/ 





































1 



/ 



r 







































// 



'-' 







































( 







































10 





/ 







































/ 



/ 









































/ 



























1 















I 2 3 -i 5 6 7 8$ 



Percentage ferric oxide in cements (applicable to curve A). 



Fig. 1. Examples of variation of percentage loss in tensile strength with the iron content 

 of cements (curve A and with the concentration of sulphide solutions (curve B). 



A STUDY OF THE CHEMISTRY INVOLVED 



In preparing the test pieces after the solutions of higher con- 

 centrations had been reacted, it was noticed that there was an 

 abnormal rise in temperature and that the mixture turned green. 

 Some of the cements showed these characteristics in a greater 

 degree than others. The color was much lighter when the bri- 

 quettes and pats were dry — becoming light bluish green. It 

 seemed very likely that the production of color was connected 



