Alkali-activated material synthesized from co-utilization of waste glass powder and steel slag

Rapid urbanization has increased carbon emissions and solid waste generation, such as waste glass and steel slag, posing significant environmental challenges. This study investigates the combined use of waste glass powder (WGP) and calcium-rich steel slag as precursors for alkali-activated materials (AAMs). Although WGP offers promising reactivity, its long setting time restricts application. To overcome this limitation, WGP was partially replaced with 10–50 % steel slag obtained either from the primary steelmaking process (primary slag, PS) or from both primary and secondary refining processes (mixed slag, MS). The findings show that incorporating either PS or MS significantly reduced the setting time of the WGP-based AAMs. Notably, adding 20 % steel slag reduced the initial setting time from over 24 h to about 70 min. For compressive strength, WGP-based AAMs incorporated with PS outperformed those with MS. Specifically, samples containing 20 % PS achieved double the strength of those with equivalent MS content. This is mainly due to the existence of high portlandite content in PS, which promotes the formation of C-S-H gels. In contrast, the lower strength in samples containing MS was attributed to the presence of unreacted calcite crystalline phases, which weakened the gel network. The optimal mix was identified as 20 % PS and 80 % WGP, achieving a 28-day compressive strength of 42.9 MPa (with initial 24 h curing at 60°C) and an initial setting time of 66 min under ambient conditions. These findings highlight the potential of reusing steel slag and waste glass as effective precursors in AAM production, contributing to sustainable resource utilization and environmental protection.