Sustainable Cement Sand Bricks: Utilizing Palm Oil Fuel Ash (POFA) and Cockle Shells as Cement and Sand Replacements for Enhanced Performance and Eco-Efficiency

Abstract Sustainable bricks are vital for eco-efficiency and green building. Their popularity is rising in construction due to raw material shortages, the environmental impact of cement, and sand depletion in brick production. This study aims to evaluate the compressive strength, water absorption, and initial rate of absorption of sustainable bricks made from POFA and cockle shell waste, following American Society for Testing and Materials (ASTM) standards for non-load bearing bricks. POFA replaced 10% of the cement, while cockle shells replaced 10%, 20%, and 30% of the sand. The cement/sand ratio was 1:6, and the water/cement ratio was 0.5. Water curing was used for the brick samples. Results indicated that the optimal mix with 10% POFA and 20% cockle shell yielded the highest compressive strengths of 19.2 MPa on day 7 and 27.2 MPa on day 28, while the mix with 10% POFA and 30% cockle shells showed the lowest water absorption at 8.17% and initial absorption rate at 13.40 g/min/193.55 cm² on day 28. In conclusion, POFA and cockle shell waste are promising materials for sustainable brick production.