Performance of sustainable lightweight foam concrete prepared using palm oil fuel ash as a sand replacement

In recent years, the use of waste materials as sand replacements has gained attention owing to the increased severity of sand depletion and its consequences on river and forest ecology. Part of the way to mitigate the sustainability issue is by utilization of palm oil fuel ash (POFA) in the fabrication of concrete. POFA is produced in large quantities as a by-product in Southeast Asian countries, resulting in disposal, economic, and health adverse consequences. This study investigates the performance of foam concrete containing 0-40% POFA as a sand replacement. Foam concrete with a targeted oven-dry density of 1500 kg/m3 was prepared using cement, sand, POFA, water, protein foaming agent, and superplasticizer. Mechanical and transport properties, microstructures, and sulphate resistances of the formulated foam concrete mixtures were investigated. Results revealed that with an increase in the POFA content, the mechanical properties and microstructure of the foam concrete significantly improved. Using POFA, the capillary sorption and gas permeability gradually enhanced, and optimum water absorption ability and thermal conductivity were obtained using 30% POFA. Additionally, with an increase in the POFA content, the foam concrete exposed to sulphate attack demonstrated higher expansion, strength loss, and microstructure deterioration. In conclusion, the incorporation of POFA as a sand substitute into foam concrete improved the mechanical properties, microstructure, and transport properties, increased the shrinkage, and decreased the sulphate resistance of foam concrete.