C 3 S dissolution was studied at highly diluted conditions, i.e., at a w/s ratio of 10 000, to prevent C-S-H and CH formation. First, we note that the reference curve for the C 3 S dissolution in ultrapure water is similar to previously reported dissolution experiments: the calcium and silicon concentrations immediately start to increase after contact of the C 3 S with water (Figure ) until complete dissolution is achieved (after approximately 20 minutes) . After a few minutes, the dissolution rate slows down and reaches zero when the C 3 S is fully dissolved. Note that when comparing with dissolution rate data from the literature, the differences arising from the choice of specific surface area used for the rate normalization must be addressed. A prominent dataset obtained by Nicoleau et al. used the geometric surface area (GSA) derived from the particle size distribution. The geometric surface area of the C 3 S sample used herein was therefore estimated by dividing the specific surface area (SSA) measured by BET by a factor of 2.5, as proposed by Fournier et al. for glass samples. The initial dissolution rate in water calculated using this estimated GSA value is close to the average of the values measured by Nicoleau et al. far from equilibrium (i.e., in domain I as defined by Nicoleau et al.