Understanding the temperature-dependent workability of cement paste with polycarboxylate superplasticizer

Abstract

This paper aims to clarify the role of polycarboxylate superplasticizer (PCE) on the workability of cement paste under different temperatures ranging from 5 to 35 °C. The temperature-induced change in the aggregate morphology of PCE has been studied to reveal its dispersion efficiency, given its surfactant nature. The results indicate that the workability of cement paste with PCE gradually increases with a rise in temperature, and a similar trend is observed in quartz powder paste, where the effect of hydration can be disregarded. The improvement in dispersing efficiency of PCE is attributed to it being adsorbed as aggregates in both cement and quartz powder systems. Usually, the concentration of PCE in the cement interstitial solution exceeds the critical micellar concentration (CMC), which results in PCE aggregating in size but exhibiting numerous reconstituted branch chains. These findings suggest that cement hydration was not a dominant factor affecting the workability of cement paste at an early stage (within 10 min) with temperature rise, which makes PCE aggregate and enhances its dispersion efficiency in cement-based materials.