Tailings as low-carbon supplementary cementitious materials: A critical review

Global decarbonization targets are accelerating the low-carbon transition of the construction industry. Meanwhile, the massive accumulation of tailings worldwide poses significant environmental risks. Driven by the need to meet global decarbonization targets while mitigating the environmental burden associated with tailings stockpiles, the use of tailings as supplementary cementitious materials (SCMs) to partially replace ordinary Portland cement (OPC) has received considerable attention. Nevertheless, widespread application remains constrained by several critical challenges, including inherently low reactivity, substantial deterioration of rheological properties, the absence of unified standards, and potential secondary pollution. Furthermore, existing research addressing these issues remains fragmented. To overcome these barriers and provide a comprehensive understanding, this review establishes a foundational framework examining the physicochemical properties, hydration mechanisms, fresh-state performance, and advanced activation technologies of tailings-based SCMs. Building on this foundation, the review further integrates utilization strategies customized for distinct tailings types, life cycle assessment (LCA), and artificial intelligence (AI)-assisted optimization to support sustainable, large-scale implementation. This integrated approach aims to highlight potential pathways from laboratory research to industrial application, providing insights and perspectives for the low-carbon transition of the construction sector, the sustainable management of solid waste, and the development of unified industry standards.