A review on carbon-neutral valorization of industrial solid waste in low-carbon binders

The cement industry, responsible for 8 % of global COQ emissions, faces a critical challenge in balancing increasing demand with the urgent need to reduce carbon footprints. Simultaneously, the rapid accumulation of industrial solid waste (ISW) has revealed significant limitations in traditional waste management methods, particularly landfilling. To address these dual pressures, this review matches distinct ISWs reactivity profiles to appropriate low-carbon binder systems, establishing a waste-valorization pathway to carbon neutrality for decarbonized construction. We propose a systematic classification of low-carbon binders based on their carbon mitigation approaches and bonding mechanisms: (1) low-clinker cement, (2) alkali-activated binders, and (3) carbonatable binders. By analyzing the physicochemical properties and reactive phases of 17 major ISWs, we determine their applicability to these three binder systems. Each category is thoroughly analyzed across their raw material characteristics, production technologies, performance attributes, microstructural features, environmental impacts, economic viability, and industrial feasibility. Key findings show that low-clinker cement achieves 20-50 % carbon reduction but is limited by raw material availability. Alkali-activated binders exhibit higher compressive strength than Portland cement but face challenges due to the high carbon footprint of alkaline activators. Carbonatable binders enable rapid hardening via COQ mineralization while achieving negative carbon footprints, positioning them as exceptional carbon sequestration materials. The challenges impeding the industrial-scale application of these three binders are critically analyzed, and innovative solutions are proposed to overcome these barriers. This review presents a unified framework synergizing ISW valorization with carbon-neutral construction. It delivers a practical roadmap for accelerating the cement industry's transition to net-zero emissions.