Net ecological benefits of co-processing papermaking waste into alkali-activated slag mortar building materials: a gate-to-gate LCA approach

Global climate crisis and waste disposal costs drive the need for circular industrial models. This study investigates whether industrial symbiosis through co-disposal of papermaking waste and blast furnace slag can convert these materials from waste to resources. Using a system expansion Life Cycle Assessment framework, we assessed alkali-activated mortars based on global warming potential, water footprint, and toxic impacts. Results indicate that high-volume waste substitution significantly improves the material’s environmental profile, achieving a net-negative Global Warming Potential of − 7.9 kg CO 2 eq/m³ and a 129% net environmental benefit for human health damage compared to the baseline. These results occur because the avoidance of landfill-related greenhouse gas emissions and primary material production outweigh the impacts of chemical activation. This study outlines a structured approach to decarbonizing construction materials. It shows how technological innovation can strengthen competitiveness within circular economic systems. This work verifies the technical feasibility of regenerative material strategies and identifies activator optimization as a critical factor for advancing next-generation sustainable materials, thereby offering practical guidance to help industrial sectors meet global sustainability requirements.