Effect of sustain-released polycarboxylate superplasticizer on the cement hydration

In order to improve the fluidity retention performance of cement, monomers containing ester groups were introduced into sustain-release polycarboxylate superplasticisers (PCEs). Two different kinds of PCEs were designed and synthesized by free radical polymerization. The chemical structure of PCEs was characterized by FT-IR and GPC, the effect of the amount of hydroxypropyl acrylate of sustain-release PCEs on the retention performance was investigated, and the hydration kinetics of cement with PCEs was observed by hydration heat and SEM. The results showed that the addition of ester group in PCEs can delay the cement hydration process, PCEs with the ester group has less initial dispersion, and the decomposition of the ester group can enhance its later dispersion, which is the main reason for the slump increase of fresh concrete over time. It is suggested that PCE containing the ester group can be used to delay the cement hydration and improve the fluidity loss of fresh concrete.