Effects of functionality and stereochemistry of small organic molecules on the hydration of tricalcium silicate

The retardation and the maximum rate of tricalcium silicate (C3S) hydration induced by organic molecules were rarely measured as a function of their molar concentration and prevent us to identify the effect of specific functional groups carried by the molecules. In this study, the maximum rate of C3S hydration which is proportional to the maximum heat flow and the retardation led by different concentrations of organic molecules was determined using the monitored calorimetric curves of the C3S pastes. The effect of the charge, functionality and stereochemistry was studied by using a set of sugar alcohols (d-glucitol, d-galactitol…), sugar acid anions (d-gluconate, d-galactarate…), carboxylate (adipate) and amines with functionalized sulfonate, carboxylate and phosphonate groups (EDTA, EDTMP…).This study reveals that the maximum rate of C3S hydration is enhanced in the presence of the organic molecules and that the retardation is increased with their concentration. The nature of the ending functional group of the molecules (hydroxyl, hydroxy-carboxylate, carboxylate, sulfonate or phosphonate), their main chain group (hydrocarbon or polyol chain) and the stereochemistry of their hydroxyl groups are shown to play a role.