The effect of partial substitution of sand with palm ash on enhancing concrete properties

The utilization of discarded materials as components in concrete production has become increasingly common. This study investigated the preparation and replacement of palm ash (palm frond ash) by the weight of sand and its impact on the properties of fresh and hardened concrete. The replacement proportions were 0%, 5%, 10%, 15%, and 20% by the weight of sand. The results indicated that the concrete slump decreased as the replacement content increased, with the reference mix recording the highest slump. Laboratory results showed that the reference mix exhibited the highest values for compressive strength and splitting tensile strength at 7 days, but at 28 and 90 days, the replacement levels recorded superior values for all ash content. Specifically, the compressive strength improved by 5.5% and 25%, while the splitting tensile strength improved by 13% and 18%, for 28 and 90 days, respectively, with increasing replacement content. Moreover, the modulus of elasticity results at 90 days showed the best values for all ash content, exhibiting an improvement of 11.5% with increasing replacement content. The microstructure of the concrete specimens was observed to be denser, with refined pores, as the amount of palm ash increased compared to the reference mix. This was evident from the increasing values of oven-dry density and ultrasonic pulse velocity, as well as the decreasing values of water absorption and sorptivity, which decreased by 27% and 47%, respectively, with increasing replacement content.