Evolution of CTE–temperature curves of HCP with hydration time

Abstract

Hydrating cement paste (HCP) may be considered as a kind of porous material. The changes of its pore system and internal moisture state with cement hydration certainly influence its thermal expansion response. This study investigated the influence of hydration time on the coefficient of thermal expansion (CTE) of HCP. Specimens (inner diameter 8 mm × 50 ± 0·5 mm long) were prepared using two water/cement ratios of 0·32 and 0·42. The linear thermal expansion of HCP was measured by a fused silica dilatometer after the HCP had been cured for different periods. The CTE–temperature curves of HCP were plotted from 30 to 60°C at intervals of 5°C. The results demonstrated that the CTE–temperature curve showed an approximately linear decrease, and its linear slope can be regarded as a strong logarithmic function of hydration time. Moreover, its linear slope showed a linear relationship with the degree of hydration. This evidence may potentially be used to show that the hydration development of pure ordinary Portland cement paste can be estimated on the basis of its thermal expansion characteristics over different hydration periods.