Sustainable Concrete Solution: Utilizing Palm Oil Fuel Ash and Metakaolin in Coconut Shell Aggregate Lightweight Concrete

Abstract The adoption of sustainable materials in the manufacturing of concrete has received considerable attention in recent years due to the environmental issues linked to conventional cement production. The objective of this study is to examine how the inclusion of palm oil fuel ash (POFA) and metakaolin (MK) as substitutes for cement affects the mechanical characteristics of lightweight concrete (LWC) that incorporates coconut shell as a partial substitute for coarse aggregate. The proportion utilised for MK and coconut shell remained constant, with 10% and 50% substitution, respectively. However, the proportion of POFA varied, ranging from 5% to 20% with increments of 5%. The study concluded that including 5% of POFA in coconut shell LWC resulted in the highest compressive strength with an increase of 68.55%, flexural strength with an increase of 39.29% while the split tensile strength was 32.18% and the lastly, was the lowest water absorption which 3.75% at 28 days of concrete age. Nevertheless, the slump value decreases as the percentage of POFA substance increases.