The isothermal calorimetry results for the five different pastes are presented in Figure 1. In the figure, it is clear that the addition of any of the four alkali mixtures results in an acceleration of the early cement hydration, as the primary hydration peak is shifted to an earlier time and also generally increased in magnitude. These measurements are quite consistent with previous ones concerning the addition of NaOH to cement pastes with w/c=0.40 or 0.55 6 and w/c=0.45. 4
Figure 1. Isothermal calorimetry measurements on hydrating cement pastes with various alkali additions, all with w/c=0.40.