Strength Evaluation of Palm Oil Fuel Ash and Rice Husk Ash as Partial Cement Replacement in Concrete for Sustainable Construction

The construction industry's dependence on Portland cement considerably increased global carbon emissions, which highlighted the need for environmentally friendly alternatives. This research explored the application of rice husk ash (RHA) and palm oil fuel ash (POFA), two common agricultural byproducts in Malaysia, as partial cement replacements in concrete. The study examined the mechanical performance and durability of several POFA–RHA concrete mix designs with the goal of reducing environmental impact while maintaining structural integrity. A systematic approach was applied for material characterization, which included advanced methods such as Field Emission Scanning Electron Microscopy (FESEM). The workability, compressive strength, and water absorption of concrete samples with varying POFA and RHA proportions were assessed. The findings showed that a mixture containing 25% POFA and 5% RHA achieved notable improvements in strength and durability while reducing water absorption. In contrast, higher replacement levels reduced workability and performance due to increased water demand and particle aggregation. Overall, the combination of 25% POFA and 5% RHA delivered substantial enhancements in strength, durability, and water absorption.