Application of metallurgical ferronickel slag in building materials: A review

Ferronickel slag (FNS) is an industrial solid waste discharged during the production of ferronickel alloy. The annual discharge and total stockpile of FNS keep rising due to the increasing global demand for nickel resources, but its comprehensive utilization rate remains low. Using FNS as supplementary cementitious material (SCM) or fine aggregate can improve the comprehensive utilization rate of FNS and reduce the impact of building materials on the ecological environment, which conforms to the concept of green, environmental protection and sustainable development. This paper reviews the research results of FNS applied in building materials, especially the related research of FNS as SCM, fine aggregate and geopolymer. The results show that when FNS is used as SCM, its active component is less, the degree of hydration reaction is lower, and the substitution rate is not easy to exceed 20 %. However, mechanical ball milling can significantly enhance the filling effect of FNS and increase its amorphous phase content, thereby improving the performance of FNS. In addition, with the introduction of alkali activator, the reactivity of the cementitious system can be further stimulated. The active excitation method increases the substitution rate of FNS to 30 %, which broadens its application range and efficiency. When FNS is used as fine aggregate, when the replacement rate is set at 40%–50 %, the working performance, mechanical properties and durability are the best. Nevertheless, how to solve the potential alkali-silica reaction of FNS fine aggregate is the focus of future research. In addition, the establishment and performance research of FNS geopolymer composite system still need to be further explored. Finally, combined with the research results of this paper, the future research prospects are put forward.