Hydration heat and kinetics of composite binder containing blast furnace ferronickel slag at different temperatures

The hydration heat of composite binder containing up to 70 % blast furnace ferronickel slag (BFFS) was determined at 25 degrees C, 45 degrees C and 60 degrees C. The hydration kinetics process and parameters were simulated and analysed. BFFS shows pozzolanic activity in a strong alkaline solution. Increasing the BFFS content retards hydration and reduces the exothermic rate. The high temperature dramatically promotes hydration, especially for the composite binder containing no more than 30 % BFFS. The hydration kinetics process involves nucleation and crystal growth (NG) -> interactions at phase boundaries (I) -> diffusion (D) at 25 degrees C and 45 degrees C. However, this process becomes NG -> D at 60 degrees C. The addition of BFFS decreases the overall hydration rate. BFFS has a smaller effect on the overall hydration of the composite binder than ground granulated blast furnace slag, but has a greater effect than fly ash.