Sustainable geopolymer cement synthesized from aluminium dross using biomass-derived activators for structural thermal and microstructural analysis

The conversion of industrial and biogenic wastes into construction materials offers an effective pathway toward low-carbon and circular-economy cement alternatives. This study synthesises geopolymer cement using black aluminium dross as the aluminosilicate precursor and biomass-derived calcium hydroxide combined with sodium carbonate as a hybrid alkaline activator. Structural and microstructural analyses (XRD, FTIR, SEM-EDS) confirm the formation of sodium aluminosilicate hydrate (N-A-S-H) gel as the dominant binding phase. TG-DSC analysis indicates good thermal stability through the dehydration and dihydroxylation regions, while DLS results demonstrate stable dispersion of dross-derived particles in the alkaline medium. The proposed approach valorises hazardous industrial residues and renewable calcium sources, demonstrating a viable route for sustainable binder development. The absence of mechanical testing is noted as a limitation, and future studies should incorporate compressive strength and durability evaluation for application-level validation.