International Research Journal of Education and Technology

Concrete is the most widely used construction material, but its environmental impact mainly due to Ordinary Portland Cement (OPC), which contributes about 7–8% of global CO₂ emissions has raised serious sustainability concerns. Geopolymer concrete offers an eco-friendly alternative by completely replacing cement with pozzolanic materials like fly ash and alkali-activated solutions as binders. This study focuses on selecting suitable materials and developing a mix design to achieve the required strength and workability, considering factors such as fly ash content (25%, 30%, and 35%), fineness, and proportions of aggregates and alkaline solutions. The ratio of alkali-activated solution to fly ash is maintained at 0.45, and sodium hydroxide to sodium silicate ratio at 2.5, with sodium hydroxide solution prepared 24 hours before casting. Both conventional concrete cubes and fly ash-based geopolymer concrete cubes are casted conventional cubes are water-cured, while geopolymer cubes are oven-cured at 60°C for 24 hours. Finally, their compressive strengths are compared to evaluate performance.

Key Words:  Fly ash, Alkali activated solution, Geopolymer, Sodium hydroxide solution, Sodium silicate solution, Oven Curing, Moles