Early Hydration of Tricalcium Silicate: A Solid Reaction with Induction and Acceleration Periods

The hydration of tricalcium silicate was studied using a sample with a limited particle size distribution. The hydration reaction was analyzed as an example of general solid reactions having induction and acceleration periods. The first product, which may have a structure similar to the reactant, forms on the surfaces of reactant grains. The nuclei of the stable product are produced in the first product layer and act as reaction centers; the main reaction to form a stable product occurs rapidly in the acceleration period. In the hydration of calcium silicates, hydrates produced in this stage are poorly crystalline and metastable and change gradually into a more stable form.