Valorizing Hazardous Spent Pot Lining in Alkali-Activated GGBS System: Synergistic Effects of Mineralized Polyacrylamide on Hydration, Strength, Microstructure, and Environmental Impact

Resource utilization of hazardous modified spent pot lining (MSPL) within alkali-activated materials faces a critical dual bottleneck, which is the inherent brittleness of alkali-activated materials and severe performance degradation triggered by MSPL incorporation. To address this limitation, this study proposes a synergistic regulation strategy employing pre-synthesized calcium carbonate-mineralized polyacrylamide (CaCO₃@PAM) hybrid micro-filler, yet enabling safe resource utilization of MSPL while mitigating the intrinsic brittleness and performance degradation of waste-blended matrices. Unlike conventional physical blending approaches, which suffer from alkaline degradation and particle agglomeration, this organic-inorganic architecture is fabricated via in-situ mineralization to retain structural integrity under highly alkaline conditions. Multi-scale characterization techniques are utilized to elucidate dosage-dependent regulating mechanisms across systems with MSPL dosages of 0-30 wt.% and hybrid filler dosages of 0-1.5 wt.%. The results show that MSPL inhibits C-A-S-H gel formation through CaF₂ passivation. By contrast, the addition of CaCO₃@PAM reverses such degradation via concurrent pathways. First, chemical compensation enabled by heterogeneous nano-nucleation and localized Ca²⁺ supply, which increases 28-d flexural strength to 6.6 MPa (G100M0-P5) and 6.7 MPa (G100M0-P10). It also improves immobilization of fluorides and heavy metals through precipitation and chelation, ensuring leachability below regulatory thresholds. Importantly, the hybrid filler effectively mitigates the abnormal rapid-setting behavior induced by MSPL and extends the workable setting time to satisfy practical engineering requirements. This study establishes a micro-regulation strategy based on mineralized polymers that simultaneously resolves mechanical fragility, durability risks and environmental hazards of MSPL-containing alkali activation. This study offers a feasible framework for the safe valorization of hazardous industrial waste in low-carbon sustainable construction materials.