Environmental benefits and sustainability potential of alkali-activated mortars derived from sandstone processing waste: a life cycle assessment study

The current study comprehensively evaluates the environmental impacts of the alkali-activated multi-binder mortars fabricated from sandstone processing residue (SPR) co-added with other locally sourced, less-valorized by-products and wastes. A cradle-to-gate approach was adopted to quantify the implications of the developed alkali-activated mortars across eighteen different impact categories using the ReCiPe 2016 method. To obtain the optimum merger, a hybrid entropy-weighted gray relational analysis was employed combining workability, mechanical, durability, and sustainability indices. Additionally, sensitivity analysis was integrated into the decision-making to assess the variations occurring in the relative rankings of the mortars due to haulage. It was revealed that quaternary amalgamations performed better than ternary ones regarding overall engineering performance and sustainability. Indeed, the mix M6 (50% stone residues + 10% arc furnace slag + 10% pulverized ash) is suggested for achieving compliance between performance and ecological impacts. Terrestrial ecotoxicity potential (TEP) and marine ecotoxicity potential (MEP) exhibited the highest ecological burdens. In contrast, the activators and transportation logistics emerged as the most critical factors influencing the overall environmental profiles. Sensitivity analyses performed for different transportation scenarios revealed the possibility of reducing the CO2 footprints of the developed mortars below that of the conventional Portland-based mix by as much as ~ 6%. The findings underscore the importance of integrating comprehensive life cycle analysis tools in guiding the development and commercialization of alkali-activated cementitious materials. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2026.