CLINKER COOLING, GRINDING, AND STORAGE. 



541 



TABLE 199. 

 EFFECT OF CALCINED SULPHATE ON SET OF CEMENT. (DYCKERHOFF.) 



Results obtained by Dyckerhoff * are given in the table above. 

 It is unfortunate that no analysis of the cement experimented on is 

 obtainable, in view of the remarkably great retardation effected by 

 very small percentages of sulphate. 



A very unusual set of results, obtained in experiments, by Messrs. 

 Kniskern and Gass, has recently been published f by Prof. R. C. Car- 

 penter. Clinker was procured from a cement-plant in unground form 

 and ground in the laboratory, being mixed with various percentages 

 of gypsum. The results are as follows : 



TABLE 200. 

 EFFECT OF GYPSUM ON SETTING-TIME. (KNISKERN AND GASS.) 



These results are shown diagrammatically in Fig. 137 and compari- 

 son of this curve with those of Figs. 135 and 136 will show their unique 

 character. The maximum effect was obtained with 1J per cent of 

 gypsum, and a rapid decrease in effect was shown when 2 per cent or 

 more was used. Unfortunately no analysis is given of the cement 

 experimented on, so that we cannot judge whether or not there is any 

 reason for these curious results. 



* Proc. Inst. Civ. Engrs., vol. 62, p. 156. 1880. 



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



