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Heat of Hydration

The heat of hydration was determined by the testing laboratories using the ASTM C186 heat of solution test method [1]. For this test, cement pastes with w/c=0.4 were 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 CEMHYD3D, hydration of a w/c=0.4 cement paste under sealed conditions at 23 ºC was conducted for cements 135 and 136. Tables 3 and 4 provide a comparison of the values determined using the standard ASTM C186 method to those predicted by CEMHYD3D. In every case, the CEMHYD3D value is within two standard deviations of the average value determined in the CCRL testing program. It is observed that the CEMHYD3D and ASTM C186 values exhibit excellent agreement for the 7 d specimens, with CEMHYD3D slightly overpredicting the measured values at the testing age of 28 d, as it also did for the degree of hydration results presented in Figures 9 and 10.


 
Table 3: Heat of Hydration Determinations for Cement 135 (w/c=0.4)
Age ASTM C186 average (J/g) ASTM C186 standard deviation CEMHYD3D prediction (J/g)
7 d 326.4 21.8 338.5
28 d 360.2 19.2 396.0


 
Table 4: Heat of Hydration Determinations for Cement 136 (w/c=0.4)
Age ASTM C186 average (J/g) ASTM C186 standard deviation CEMHYD3D prediction (J/g)
7 d 318.8 20.5 319.1
28 d 359.4 33.5 381.0


Next: Mortar Strength Development Up: CEMHYD3D Results Previous: Hydration Kinetics