The influence of nano-SiO₂ on the hydration kinetics of Portland cement paste

The hydration kinetics of Portland cement with and without nano-SiO₂ (NS) were evaluated via isothermal calorimetry and investigated based on the mathematic method of the Krstulovic-Dabic model in this paper. NS was used to substitute Portland cement at 0, 1 and 3 wt. % by mass. The test results obtained in this study indicated that the hydration process of Portland cement was dramatically promoted in terms of increasing the heat released and the heat release rate when NS was added. From the Krstulovic-Dabic model, the dynamics process of Portland cement was controlled by nucleation and crystal growth (NG), phase boundary interactions (I) and the diffusion (D) process, it does not matter whether there was NS or not, but the transformation of the controlling process occurred at a lower hydration degree for the NS-added pastes. Moreover, the increase in NS content increased the values of the kinetics parameters KNG and KI, but decreased KD and the reaction exponent to a different degree.