Loss-on-ignition

As the isothermal calorimeter employed in this study has insufficient sensitivity and baseline stability for use beyond 24 h, LOI measurements were performed to quantify the continuing hydration in the cement pastes. Results are summarized in Table 2 which indicates the achieved degrees of hydration of the mixtures as a function of age from 1 d to 91 d. Consistent with the isothermal calorimetry results presented in Figure 1, all four of the mixtures with additional alkalis accelerate the achieved hydration to ages on the order of 7 d. However, beyond that point, significant differences are observed, as the alkali sulphate mixture is observed to strongly reduce the achieved hydration, the alkali hydroxide mixture is observed to generally somewhat reduce the achieved hydration, and the LiOH and LiNO₃ additions are observed to maintain a degree of hydration basically equivalent to that of the low-alkali cement control specimen.