Abstract: A kinetic study by heat evolution is reported to research the influences of the dosages and fineness of steel slag powder on the hydration process and mechanism of cement. Results demonstrate that fine steel slag powder shortens the induction period; on the contrary, coarse steel slag powder delays the induction period. The acceleration period shortens in the presence of 15% dosage of steel slag powder, while elongates when the content of steel slag powder exceeds 15%. Increasing the specific surface area or dosage of steel slag powder brings forward the third exothermic peak. The total heat release declines with the increase of steel slag powder content; but climbs with the increase of specific surface area. The acceleration period is controlled by the nucleation kinetics. In the acceleration period, steel slag powder would cut the reaction resistance; but with the increasing of steel slag powder content, reaction resistance rebounds slightly. Moreover, the reduction of fineness also boosts the reaction resistance. Decay period is controlled by diffusion; diffusion resistance increases and then decreases with the increasing of steel slag powder, and increases with the increasing of specific surface area.The research findings lay a foundation for further studies on the hydration heat and hydrokinetics of steel slag powder-cement composite material.

Key words: steel slag powder-cement composite binder, content of steel slag, fineness, hydration heat, hydration kinetics