Understanding the rheology and hydration behavior of cement paste with nickel slag

Abstract

Nickel slag (NiS), an industrial waste slag produced by laterite nickel ore, is a potential mineral additive utilized in cement-based materials. This study compared the effects of NiS, fly ash (FA) and blast furnace slag (BFS) on the rheological properties and hydration behavior of cement paste, and further evaluated the rheological properties of ternary cementitious system. The results show that adding NiS is unfavorable to the rheological properties of cement paste. More specifically, the yield stress of the cement paste first increases and then almost keeps unchanged with increasing NiS content, while the plastic viscosity shows a continuous increase behavior. The cement pastes with BFS or FA exhibit improved rheological properties than the NiS containing cement pastes. Compared with the PC-NiS-FA ternary pastes, the PC-NiS-BFS ternary pastes have smaller shear thinning intensity, larger yield stress and higher plastic viscosity. The exothermic rate and hydration heat of NiS cement paste within 2 h, normalized to the amount of cement, are higher than those of cement pastes with BFS and FA.