272 



CEMENTS, LIMES, AND PLASTERS. 



10 20 30 40 50 



FIG. 59.* Tensile strength Rosendale cements, Boston Main Drainage, 1885. 



500 



400 



300 



200 



100 



50 



100 



150 300 

 AGE IN DAYS 



350 



300 



350 



FIG. 60. f Tensile strength natural cements, Sault Ste. Marie, 1894. 



The effect on the tensile strength of varying the proportion of 

 sand is well shown in the tests made by Sabin J and summarized in 

 Table 130. These tests are shown diagrammatically in Fig. 61. 



* From Johnson's "Materials of Construction", p. 568. 



t Ibid., p. 570. 



t Report Chief of Engineers, U. S. A., 1895, p. 2982. 



