Replacing conventional activators with a waste-glass-derived dry alkaline activator for sustainable one-part geopolymer composites

One-part geopolymer concrete (GPC) offers a safer and more sustainable alternative to conventional alkali activation by eliminating hazardous liquid alkaline solutions. This study presents a novel thermochemical approach for synthesising a dry alkaline activator (DA) using waste glass powder (WGP). The effects of SiO 2 /Na 2 O molar ratio (Ms = 0.5, 1.5, 2.5), activation temperature (T of 150 to 350 °C), duration (t of 1 to 3 h), and water dosage (w of 0 to 10%) were investigated using a Taguchi design of experiments. FTIR and SEM-EDS analyses confirmed sodium silicate formation, with optimum efficiency (80%) achieved at Ms = 1.5, 150 °C, 2 h, and 10% water. This optimised DA was used to produce one-part geopolymer (GP) composite mixes at different DA/binder ratios (0.3–0.5), which were tested for rheological, mechanical, and microstructural properties. Rheological characterisation revealed shear-thinning behaviour with elastic-dominant viscoelasticity. Compressive strength increased with activator dosage, reaching up to 24.5 MPa after 28 days, under heat curing for 24 hours, surpassing that of liquid-activated GPC. Sustainability analysis revealed up to 68% CO 2 and 57% cost reduction compared with conventional GPC. Overall, the findings demonstrate the feasibility of waste-glass-based dry activators as a cleaner, safer, and economically viable alternative for scalable one-part GP production aligned with circular economy principles.