Utilization of blast furnace slag-based binder as an eco-friendly and cost-effective material in cementitious mine backfill: Mechanisms, application and perspectives

In conventional cemented paste backfill (CPB) applications, Ordinary Portland Cement (OPC) has been the primary binder; however, it is associated with drawbacks like elevated costs, high carbon emissions, and durability. Granulated blast furnace slag (slag), a byproduct of the ironmaking process, emerges as a promising sustainable solution. This review systematically evaluates three slag-based binders—slag-cement blends (SCB), alkali-activated slag (AAS), and alkali-sulfate-activated slag (ASAS)—focusing on their hydration mechanisms, rheological characteristics, mechanical properties, microstructure, sulfate resistance, and heavy metal solidification capabilities. Results indicate that SCB-CPB exhibits enhanced fluidity and late-stage strength over OPC-CPB, albeit with reduced early-stage strength. While AAS exhibits superior comprehensive properties, its application is hindered by the high cost and corrosiveness of alkali activators. In contrast, ASAS emerges as a balanced solution, offering early and late-age strength second only to AAS, while being the most cost-effective and lowest-carbon option. Moreover, the future prospects of slag-based binders in CPB are also discussed, providing valuable guidance for their formulation and deployment. The findings offer valuable insights for the development and implementation of cost-effective and environmentally friendly slag-based binders in CPB practices.