Influence of steel slag on strength and microstructural characteristics of fly ash-based geopolymer concrete

Geopolymer concrete (GC) utilizes industrial solid waste like steel slag, fly ash, and rice husk ash, offering a sustainable alternative to traditional cement. By reducing reliance on cement, GPC helps mitigate carbon footprints and promotes eco-friendly construction practices. With its significant commercial potential, GPC is poised to contribute to sustainable development in the construction industry. The study examined various alkaline ratios (e.g., 1.5:1 and 2:1 Na2SiO3 to NaOH) and evaluated the effects on GC. Steel slag replaced FA at ratios of 20%, 30%, 40%, and 50%, and fresh characteristics and mechanical properties were assessed for both geopolymer and standard concrete. Durability tests included water absorption, sorptivity, and acceleratory corrosion (ACT). Microstructure analysis using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) was conducted on steel slag and FA-based GC samples. Steel slag enhanced the durability of FA-based GC, particularly in water absorption, sorptivity, and ACT. The geopolymer mixture containing 50% FA & 50% steel slag has exhibited significantly improved mechanical properties of 103.31%, 105%, and 119.61% compared to the control mix under ambient temperature for 28 days. This enhancement is attributed to higher calcium content in geopolymer mixes, fostering a more pronounced geopolymeric reaction, supported by microstructural research.