Evaluating the Impact of Water-Cement Ratios on the Compressive Strength and Water Absorption of Coal Bottom Ash Concrete

Coal Bottom Ash (CBA) is an industrial byproduct generated in significant quantities due to increased power consumption. Utilizing CBA as a sand replacement in concrete is considered a promising innovation for producing environmentally friendly concrete. However, determining the precise water-cement (WC) ratio is challenging due to the highly porous nature of CBA. This study examines the impact of WC ratio on the compressive strength and water absorption of CBA concrete. Concrete samples with WC ratios of 0.40, 0.45, and 0.50, incorporating 0%, 10%, and 20% CBA replacement, were evaluated. Results indicated that an increase in both CBA percentage and WC ratio led to a decrease in compressive strength and an increase in water absorption. However, with extended curing periods, compressive strength improved, and water absorption decreased. The target strength of CBA concrete was achievable with up to 20% CBA and a WC ratio between 0.40 and 0.45. A significant correlation between compressive strength and water absorption was identified for WC ratios of 0.40 and 0.45, as evidenced by the correlation coefficient (R ² ). Conversely, the R2 value for a WC ratio of 0.50 showed no clear relationship between these factors.