Environmental assessment of cenosphere and GGBFS-based geopolymers: A path to greener construction materials

This study investigates the viability of utilizing cenospheres as an alternative precursor material for geopolymer formulation, comparing their performance against ground-granulated blast furnace slag (GGBFS) across various parameters such as strength, durability, cost, and environmental impacts. A cradle-to-gate life cycle assessment was performed to evaluate the environmental impact of geopolymer mixtures containing varying proportions of cenosphere and GGBFS, relative to conventional cement mortar (CM). Additionally, a multi-criteria decision-making (MCDM) analysis was employed by assigning varied importance levels to identify the optimal formulation derived from performance (strength and durability), cost, and environmental impact. The findings demonstrate that GGBFS/cenosphere-based geopolymers lower global warming potential (GWP) by 24–33 % compared to CM. Moreover, incorporating 25–75 % cenospheres in geopolymers reduces GWP by 4–7 % and energy consumption by 5 % compared to purely GGBFS-based geopolymers. The eutrophication potential (EP) and acidification potential (AP) were also reduced by 3–10 % and 5–15 %, respectively, by adding 25–75 % cenospheres in geopolymers. However, the cost is also increased by 6–18 %. Based on the MCDM analysis, geopolymers containing cenosphere possess higher overall sustainability than conventional cement-based mortars.