SOME GENERALIZATIONS ON THE INFLUENCE OF 
SUBSTANCES ON CEMENT AND CONCRETE 
SECOND PAPER 
By J. C. Witt 
Formerly of the Bureau of Science, Manila 
This paper is one of a series published as a result of re- 
search started by me at the Bureau of Science in 1915 to in- 
vestigate the effect of some inorganic substances on cement and 
concrete.t. The work was confined to neat and mortar specimens 
with the idea of later trying the effect of the most-active sub- 
stances on concrete. Since sulphur compounds were frequently 
mentioned in the literature as destructive agents, the work was 
begun with these—first sulphides and then sulphates. The ef- 
fect of sulphides was found to be related to the iron content 
of the cement, and this led to an investigation of the reaction 
between sodium sulphide and ferric oxide.2. Also another prob- 
lem related to the effect of inorganic salts was taken up; 
namely, the solubility of cement in water. 
The work with sulphides and sulphates led to a study of the 
effect of a number of other salts ¢ on the setting time and tensile 
strength, and it is chiefly with this phase of the work that the 
present paper is concerned. A review of the literature revealed 
that while many papers had been published little definite infor- 
mation was available, and the subject as a whole showed little 
progress. No uniform method in making tests had been fol- 
lowed by the various investigators, and consequently there was 
no basis for comparing their results. 
Solutions were made from eleven salts (four concentrations 
of each) and these solutions were used in making setting-time 
_tests, and 1:3 standard Ottawa sand briquettes with four 
cements. The briquettes were stored in water and broken at 
the end of 7 days, 28 days, 180 days, 1 year, and 5 years. Each 
* Philip. Journ. Sci. § A'11 (1916) 278; 12 (1917) 183; 14 (1919) 221; 
21 (1922) 357. 
* Journ. Am. Chem. Soe. 43 (1921) 734. 
* Philip. Journ. Sci. § A 13 (1918) 147; Concrete 16 (1920) 13. 
* Philip. Journ. Sci. § A 13 (1918) 29. This will be called the “first 
paper” in the discussion that follows. 
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