EFFECT OF WATER-TO-GEOPOLYMER SOLIDS RATIO ON THE WORKABILITY AND STRENGTH OF FLY ASH AND GGBFS-BASED GEOPOLYMER CONCRETE

Geopolymer concrete (GPC) is an emerging sustainable alternative to conventional Portland cement concrete, utilizing industrial by-products such as fly ash and ground granulated blast furnace slag (GGBFS) as binders. This study investigates the effect of varying waterto-geopolymer solids ratios and extra water addition on the workability, compressive strength, and durability of GPC cured at room and oven temperatures. Experimental results indicate that increasing the water-to-geopolymer solids ratio improves workability but reduces compressive strength. GPC samples achieved a compressive strength of 33.76 MPa at 24 hours when cured at room temperature and 45.53 MPa at 24 hours when oven-cured at 60°C. Furthermore, the water absorption of GPC cured at room temperature was significantly lower (0.28%) compared to oven-cured samples (2.57%). Durability tests confirmed that GPC exhibited excellent resistance to sulfate attack, with no noticeable weight loss or surface degradation over a 30-day period. The findings highlight the potential of GPC as a viable alternative to conventional concrete, especially in applications requiring early strength development and improved sustainability.