Hydration of silicate phase and mechanical evolution in 'alite-tricalcium aluminate-gypsum' complex system
Résumé
Using simultaneously the dynamic mode rheometry and the calorimetry, it has been possible to specify interactions between the components of “alite-C3A-gypsum” system. The concept of "mechanical efficiency of calcium silicate hydrates" (R = dG' /dQ, is the increase in the elastic modulus dG' corresponding to the formation of a certain quantity of CSH, estimated by released heat dQ) was introduced to quantify the effect of the mixtures on the cohesive properties of C-S-H. For the system alite-C3A : the presence of aluminate ions decreases both the growth rate of CSH and R; for the great quantities of C3A, there is a positive effect of the surface developed by AFm on R. If gypsum is added, the hydration of alite is not very affected by the presence of C3A and R increases with the added gypsum quantity. In most cases, complex system does not behave like the sum of simple systems.