Synergistic effect and mechanism of lithium slag on mechanical properties and microstructure of steel slag-cement system

Replacement of cement with solid waste is an important method for conserving natural resources and reducing CO2 emissions. In this study, steel slag and lithium slag were used to replace cement to address the low activity of steel slag, which limits its large-scale utilization. The compressive strength, flow properties, dissolution characteristics, hydration products, and microstructure of composite cementitious materials containing steel slag and lithium slag were investigated by ICP-OES, XRD, TG, FTIR, SEM and MIP. The results showed that the addition of lithium slag into the cementitious material with steel slag improved the compressive strength. The lithium slag consumed a large amount of portlandite and promoted hydration of the steel slag to produce more C-(A)-S-H. Furthermore, the porosity and pore size distribution were optimized, the most probable pore size was reduced, and the pore complexity was increased. This research provides a solution for comprehensive use of steel slag, which contributes to high-value green utilization of solid waste.