Discussion of the paper “Dissolution theory applied to the induction period in alite hydration” by P. Juilland et al., Cem. Concr. Res. 40 (2010) 831–844

The new mechanism proposed by Juilland et al. [1] to explain the induction period in alite hydration is discussed with reference to the free energy of dissolution under typical hydration conditions calculated from published data. It is concluded that the proposed mechanism is theoretically possible but requires an unusually high interfacial energy for step formation, plus an unusually large increase in dissolution rate over small changes in the degree of solution undersaturation, compared to typical published values for silicate minerals. It is suggested that comparisons with the hydration rates of CaO and MgO might shed further light on the mechanism.