Influence of fineness on hydration kinetics of supersulfated cement

Abstract

Hydration heat evolution rate and quantity of supersulfated cements (SSCs) with three different specific surface areas (335m2/kg, 445m2/kg and 518m2/kg) were measured at 25°C by isothermal calorimetry. The hydration heat evolution quantity of SSCs improves with the increase of cement fineness, but is much lower than that of ordinary Portland cement. The hydration of supersulfated cement is accelerated by the elevated fineness, and the hydration process of supersulfated cement after induction period was divided into three periods, nucleation and crystal growth (NG), phase boundary reaction (I), and diffusion (D), which are well simulated through Krstulovic–Dabic model. The connecting points of NG process and I process, I process and D process both decrease with the increase of fineness which shows that the second exothermic peak is in advance. I process also decreases with the increase of fineness, which indicates that I process is accelerated by fineness. The hydration of supersulfated cement is sensitive to fineness, especially for the specific surface area reaching up to 518m2/kg.