Effect of the fineness of copper slag on the early hydration properties of cement–copper slag binder

Abstract

The early hydration heat and hydration process, hydration products and strength of binders containing 20% copper slag with different fineness has been studied. The ordinary Portland cement is taken as the comparison sample. Results show that the replacement of cement in the same proportion copper slag can prolong its induction period, reduce its early hydration heat and prolong the hydration process, which was caused by the dilution of cement clinker after adding 20% copper slag, the limited pozzolanic activity and the agglomeration effect of copper slag particles, as well as the chemical composition which contained heavy metal compounds. Adding copper slag can reduce both the compressive and flexural strength, while the reduction rate of flexural strength is slightly smaller than that of compressive strength. Copper slag with specific surface areas 503 m2 (kg)−1 has the optimal strength development. Hydration products of composite binders such as calcium hydroxide, calcium carbonate, calcium aluminum silicate hydrate are about the same with the comparison sample ordinary Portland cement, while calcium iron oxide content Fe is always exist. With the curing aging growing, especially for sample with the highest fineness copper slag, the hydration will be deeper and generate calcium aluminum oxide carbonate hydrate.