The influence of an ion-exchange resin on the kinetics of hydration of tricalcium silicate

The addition of a finely-ground ion-exchange resin makes it possible to modify the hydration kinetics of C3S pastes. Analyses of the liquid phase in pastes and more dilute suspensions show that the resin exchanges calcium ions for sodium ions very rapidly during the early stage of hydration and therefore the concentration of silica in solution increases. The resin impacts the hydration of C3S by other mechanisms which depends on the resin quantity added. For a high resin quantity, the induction period is very short, but the longer-term hydration is enhanced compared to a reference sample without resin. We hypothesize that the surface of the resin can provide sites for the nucleation and growth of C–S–H hydrates and/or portlandite far away from the surface of the C3S grains. This consequently increases the quantity of hydrates that can precipitate before a continuous hydrate layer forms over the surfaces of C3S particles.