Optimization of Self-Compacting Concrete Incorporating Ultrafine Palm Oil Fuel Ash Using Response Surface Methodology for Enhanced Rheological Performance and Sustainability

Abstract

Self-compacting concrete (SCC) enhances workability and eliminates the need for vibration but is prone to segregation and extended setting times. This study investigates the use of ultrafine palm oil fuel ash (UPOFA) as a partial cement replacement to improve SCC performance and sustainability. UPOFA, processed through sieving, grinding, and heating, was incorporated at 0%, 20%, 40%, and 60% replacement levels, and its effects on filling ability, passing ability, segregation resistance, and setting times were evaluated following EFNARC standards. A Customized Single-Factor Response Surface Methodology (CSF-RSM) model identified 40% UPOFA as the optimal replacement level, achieving a desirability score of 1.000. At this level, SCC exhibited an initial setting time of 8.8 h, final setting time of 11.8 h, slump flow of 729 mm, flow T500 of 2.6 s, blocking ratio of 0.95, and segregation resistance index of 12.5%, all within EFNARC standard limits. Experimental validation showed deviations below 4%, confirming the model’s predictive accuracy. UPOFA improved SCC workability by increasing paste volume and lubrication while enhancing mix cohesion and reducing segregation risks. These findings confirm UPOFA as an effective supplementary cementitious material, optimizing SCC rheological properties while ensuring compliance with EFNARC standards for sustainable concrete production.