Value-added utilization of ultrafine ferronickel slag as a novel type of high-quality mineral admixture: A feasibility study

Abstract

In this study, a novel type of high-quality mineral admixture, ultrafine ferronickel slag, is manufactured and designed, and the feasibility of its utilization in cement and concrete is systematically investigated. It was found that after mechanical grinding, ultrafine ferronickel slag can be used as a novel and special high-quality mineral admixture, which improves the microstructures and properties of concrete in an efficient way. Ultrafine ferronickel slag shows little adverse effect on the early-age strength, and effectively increases the later-age strength of concrete. It improves the resistance to chloride ion penetration and the resistance to sulfate attack of concrete. It also reduces the total porosity and refines the pore in concrete. With the increase of ultrafine ferronickel slag content, the proportion of large pores with diameters more than 100 nm decreases, and the proportion of pores with diameters less than 100 nm increases significantly, especially for the small pore with diameters less than 10 nm. In addition, ultrafine ferronickel slag presents good compatibility with polycarboxylate superplasticizer and significantly produces a pozzolanic reaction consuming portlandite. This study provides a new way for the value-added utilization of ferronickel slag and promotes the sustainable development of high-quality active mineral admixture in alternative binder design.