XI, A, 6 



Witt: The Effect of Sulphide on Cement 



281 



this decrease seems to be approximately proportional to the 

 concentration of sulphide in the solution used. It is also apparent 

 that brands A and E are again most affected by the sulphide. 

 The broken briquettes appear normal in every respect except 

 in color; there is no swelling, cracking, nor distortion. Table 

 V shows that the average loss in tensile strength caused by 

 using a given sulphide solution in place of water is greatest 

 with the cement highest in iron. 



CEMENT HIGH IN IRON CONTENT 



In order to determine how far the relationship between iron 

 content and tensile strength might hold, briquettes were made 

 from two other samples of cement much higher in iron. These 

 were designated as F and G. Sample F was a brand of cement 

 different from any other used in this work. It contained 3.44 

 per cent iron oxide (FeaOg). There was no cement of still 

 higher iron content available, so sample G was made by grinding 

 iron oxide to pass a 100-mesh sieve and by intimately mixing 

 a given weight with a portion of sample F. This added iron 

 oxide could not be considered as a part of the cement, but was 

 present as a foreign substance. The experiment was carried 

 on with the object of determining whether or not there was any 

 relation between the effect of iron which was an integral part 

 of the cement and iron which was added to the finished product. 



The tensile strengths of samples F and G are shown in 

 Table VI. 





TiVBLE VI.- 



—Effect of sulphide 



on cement high in 



iron 



content 



• 



.2 



Total 

 ferric 

 oxide 



■ ■ Tensile strength.": 



Setting time. 



Kilos per square centimeter. 



Pounds per square inches. 



1 







(FezOs) 

 in dry 

 cement. 



Neat. 



Mortar. 



Neat. 



Mortar. 





1 

 day 



7 

 days 



28 

 days 



7 

 days 



28 

 days 



1 

 day 



7 

 days 



28 

 days 



7 

 days 



28 

 days 



Initial. 



Final. 





Per cent. 























Hrs. min. 



Hrs. min. 



Fa 



3.44 



29.6 



48.1 



42.9 



17.3 



28.0 



423 



685 



611 



247 



398 



2 47 



5 15 



Pb 





15.3 



23.9 



23.2 



14.3 



17.6 



218 



341 



330 



204 



250 



2 2 



5 24 



G» 



8.63 



24.1 



38.7 



41.2 



19.7 



24.5 



343 



550 



586 



279 



348 



3 59 



5 41 



Gb 





12.6 



20.4 



18.3 



11.6 



15.5 



180 



291 



261 



162 



221 



2 47 



6 42 



" Gauged with water. 



•> Gauged with solution 1. 



= Each result represents the average of three briquettes. 



Soundness tests were made with both water and solution 1. All were satisfactory. 



The results show that the relation between iron content and 

 loss in tensile strength continues for sample F, although the 



