HIGH-STRENGTH CEMENT-FREE CONCRETE MADE FROM FLY ASH AND PALM OIL FUEL ASH

Abstract

This study investigated palm oil fuel ash as a partial replacement for fly ash in binders. As fly ash is a limited resource, incorporating renewable materials like palm oil fuel ash is crucial. The research assessed the effects of adding 5% and 10% palm oil fuel ash to fly ash-based geopolymer concrete. Samples were cured at room temperature and heated at 60°C for 24 hours. Compressive strength tests were performed at 1, 7, and 56 days. The results showed that adding palm oil fuel ash increased compressive strength by 5% to 12% at 5% addition and 10% to 33% at 10% addition. The heated curing method significantly boosted compressive strength by 74% to 79% after one day, 139% to 196% after seven days, 13% to 28% at 28 days, and 6% to 14% after 56 days. Scanning electron microscope (SEM) analysis revealed that heated specimens exhibited more interaction between palm oil fuel ash and fly ash, with fewer cracks at the 7-day curing period. However, there was no significant difference in the SEM results between heated and room temperature specimens after 56 days. The study concluded that palm oil fuel ash has excellent potential to replace fly ash partially, and after 56 days of curing, elevated and room temperature curing geopolymer concrete has approximately the same compressive strength, which is the novelty of this research.