THE EFFECT OF SULPHIDE ON CEMENT ^ 



By J. C. Witt 



(From the Laboratory of General, Inorganic, and Physical Chemistry, 



Bureau of Science, Manila, P. I.) 



ONE PLATE AND 1 TEXT FIGURE 



There has long been an opinion among cement users that no 

 materials containing sulphur compounds should ever be utilized 

 in making concrete.^ Cases of failure have been reported which 

 were attributed to sulphur compounds in some of the materials 

 used or to sulphur compounds which came into contact with the 

 finished construction.^ According to Ljamin,* calcium sulphide, 

 which is often present to a small extent in cement, has relatively 

 little effect, though Kremann and Potts * mention potassium 

 sulphide as an accelerator for the hydration of cement. There 

 are so many factors, any one of which may be responsible for a 

 failure, that it is often difficult to place the blame unless con- 

 siderable research is carried on. It is known that cinders from 

 certain sources are not satisfactory for concrete. This has been 

 attributed to the sulphur in the coal burned. It is likely that 

 some of the failures said to be due to sulphur compounds are 

 caused by other agents, and vice versa. 



A frequent source of sulphur compounds in concrete is the 

 water used in mixing. In this case they are more uniformly 

 distributed through the concrete than if present in the sand 

 or aggregate. For these reasons the sodium sulphide used in 

 the present work was added in the form of solutions. In most 

 cases, where trouble is experienced from the presence of sulphur 

 in the water used, it is likely that it is due to a mixture of 

 several compounds. We might expect to find hydrogen sulphide, 

 soluble metallic sulphides, sulphates, and possibly sulphites. It 

 is obviously impossible to attempt the solution of a problem 

 of this nature unless the effect of each substance is studied 

 separately. It is our intention to carry on work along many 

 of these lines. Work on the effect of sulphate on cement and 



* Received for publication May 10, 1916. 



' This does not refer to the addition of a reasonable amount of gypsum 

 to the cement for controlling the set. 



' Borrowman, G., Journ. Ind. & Eng. Chem. (1912), 4, 405. Desch, C. H., 

 The chemistry and testing of cement. Edward Arnold, London (1911), 75. 



*Ljamin, N., Journ. Soc. Chem. Ind. (1902), 21, 972. 



' Kremann, R., and Potts, H. E., The application of physicochemical 

 theory to technical processes and manufacturing methods. D. van Nostrand 

 Co., New York (1915), 161. 



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