Synergistic effect of waste glass and steel slag on mechanical property and microstructure of cement-based materials

Cement production significantly contributes to CO₂ footprint and the utilization of solid wastes in this process not only promotes resource conservation but also enhances the properties of the resulting product. The synergistic effect of waste glass powder (WGP) and steel slag powder (SSP) on the mechanical properties and microstructure of cement-based materials has been investigated. The findings indicate that when WGP or SSP is used to replace ordinary Portland cement (OPC) individually, with replacement levels ranging from 0 to 45 %, the compressive strength decreases considerably. In WGP group the reduction rate varies from 30 % to 50 % and in SSP group it ranges from 10 % to 50 % during the early hydration stages (3-28 d). However, by 90d the reduction is less notably. During later hydration, the pozzolanic reaction of WGP reduces the Ca(OH)₂ content and leading to a redistribution of hydration products, while SSP can be activated to form additional C-S-H gel and Ca(OH)₂. The combined use of WGP and SSP demonstrates an acceleration effect on OPC at early stages, and the hydration of SSP generates Ca(OH)₂ to promote the pozzolanic reaction of WGP during later hydration. Furthermore, the synergistic effect of WGP and SSP can deliver enhanced economic and environmental advantages.