Closed-loop synergistic valorization of electrolytic manganese residue and industrial byproducts: A low-carbon concrete paradigm via low-vacuum curing-driven circularity

Turning electrolytic manganese residue (EMR) into circular construction materials kills two birds with one stone: sustainable EMR valorization and alleviating construction resource scarcity. Herein, we fabricate a green concrete synergizing EMR with fly ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS), focusing on strength and gas permeability under low vacuum. Results indicate that GGBFS-EMR synergy achieves a performance index of 4.71 kg CO₂-eq/MPa·m³, balancing strength, low-carbon efficiency, and cost-effectiveness. Strength of EMR-compounded concrete increases initially before declining over the duration of low vacuum. A standard curing (SC) followed by low-vacuum curing (LVC) treatment reduces per unit strength carbon emissions and gas permeability coefficient by 33.3–76.9 % versus 56d SC, while SF enhances strength across all EMR ratios of 10–30 %. GGBFS supplementation further amplifies strength gains over equivalent EMR proportions. The gas permeability coefficient evolves with time and correlates linearly with mass loss rate, enabling permeability prediction based on mass loss behavior. Combined standard and low vacuum curing ensures Mn and NH₃-N compliance with regulatory limits. This approach combines EMR’s cost efficiency with GGBFS reactivity to mitigate regional FA scarcity, creating a sustainable circular system balancing ecological, mechanical, and economic criteria. Though demonstrating industrial viability and waste valorization potential, this preliminary study highlights remaining limitations in the engineering complexities of scaling low-vacuum treatment with precise cost accounting—fundamental barriers requiring resolution before commercial scaling.