Influence of type of calcium sulfate on chemical shrinkage and heat of hydration in self-leveling underlayments using ettringite binder
Chemical shrinkage of cementitious materials relates to the early-age volume change of mortar and concrete. Therefore, determining exactly the chemical shrinkage plays a significant role in predicting and preventing early-age cracking in materials using cement as binder. In this study, the chemical shrinkage of self leveling underlayment using ettringite binder is investigated by a buoyancy method, data was recorded automatically for studying the hydration kinetics of the binder. The results show that the chemical shrinkage of self-leveling underlayerments using hemihydrate CaSO4.0.5H2O is smaller than that of self-leveling underlayerment using anhydrite CaSO4. However, the hydration rate of the anhydrite-based mixtures occurs faster than that using hemihydrate.
Received: January 16th, 2018; revised: February 13th, 2018; accepted: February 28th, 2018