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

Highlights: • Ferronickel slag reduces the exothermic rate and cumulative hydration heat at 25°C. • The high temperature greatly promotes the hydration of binder with ferronickel slag. • The hydration kinetics process at 60°C is different from that at 25°C and 45°C. • Ferronickel slag has a smaller effect on the overall hydration than slag. • Ferronickel slag has a greater effect on the overall hydration than fly ash. The hydration heat of composite binder containing up to 70 % blast furnace ferronickel slag (BFFS) was determined at 25°C, 45°C and 60°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°C and 45°C. However, this process becomes NG → D at 60°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.