Ambient-cured self-compacting geopolymer concrete using neutral-grade water glass

The rising environmental impact of ordinary Portland cement production, together with the demand for durable and high-performance concrete, has accelerated the search for sustainable alternatives such as self-compacting geopolymer concrete (SCGC). This study investigates SCGC developed using industrial by-products – ground granulated blast furnace slag, fly ash, and micro silica (MS) – as binder materials. Mixes were formulated with varying binder proportions and solution-to-binder ratios using neutral-grade water glass as the sole activator under ambient curing conditions of 25 ± 2°C. Fresh and hardened properties were evaluated alongside microstructural characterization using scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Results showed that incorporating up to 15% MS significantly enhanced compressive strength (up to 74.9 MPa), tensile, and flexural performance while maintaining EFNARC-compliant flowability. Dense C-A-S-H and N-A-S-H gel formation reduced porosity and improved resistance to chloride ion penetration. The findings demonstrate that ambient-cured SCGC activated solely by neutral-grade water glass can achieve high strength and durability, offering a practical pathway towards sustainable, low-carbon construction materials.