Heat of Hydration

The heat of hydration was determined by the testing laboratories participating in the CCRL proficiency sample testing program using the ASTM C186 heat of solution test method [1]. For this test, cement paste with w/c=0.4 was prepared and stored in sealed vials (sealed curing conditions) at 23 ºC. At the time of testing, either 7 d or 28 d, the cement paste sample was digested in an acid solution and the energy released measured. By subtracting this measured value from the value determined for the starting cement powder, the heat of hydration may be determined [1]. To predict these values using the VCCTL, hydration of a w/c=0.4 cement paste under sealed conditions at 23 ºC was conducted for cement 135.

Table 3 provides a comparison of the values determined using the standard ASTM C186 method to those predicted by the VCCTL. At both ages, the VCCTL-predicted value is within two standard deviations of the average value determined in the CCRL proficiency sample testing program.

 

Table 3: Heat of Hydration Determinations for Cement 135 (w/c=0.4)

Age	ASTM C186	ASTM C186	CEMHYD3D
	average (J/g)	standard deviation	prediction (J/g)
7 d	326.4	21.8	338.5
28 d	360.2	19.2	396.0