546 



CEMENTS, LIMES, AND PLASTERS. 



practical importance, for most of the salts experimented with are too 

 costly for use. 



TABLE 208. 

 EFFECT OF VARIOUS SALTS ON SET OF CEMENT. (NmouL AND DUFOSSEZ.) 



Recent experiments on the use of solid chloride of lime as a retarder 

 have been published by Carpenter. These were carried out by the same 

 experimenters, and probably on the same cement which, when treated 

 with gypsum, gave the erratic results noted on p. 541. Carpenter sum- 

 marizes * these experiments as follows: 



"Messrs. Kniskern and Gass, in the Sibley Laboratory, ground differ- 

 ent percentages of chloride of calcium (CaCl 2 ) with cement clinker and 

 afterwards made pats, using in each case simply enough water to give 

 the material its normal consistency for this purpose. Their results 

 show that the chloride of calcium had great effect in retarding the time 

 of setting and exerted the greatest effect when about 0.5 per cent by 

 weight of the chloride of calcium was employed. On account of the 

 water required, 1 per cent of the chloride of calcium would correspond 

 approximately to gauging with a solution of 30 grams per liter in the 

 previous experiments quoted. 



CaCl 2 GROUND DRY WITH THE CLINKER. 



* Engineering News, vol. 53, pp. 13-14. Jan. 5, 1905 



