Influence of palm oil fuel ash in concrete and a systematic comparison with widely accepted fly ash and slag: A step towards sustainable reuse of agro-waste ashes

Abstract

The utilisation of locally available agro-waste ashes in concrete is a sustainable alternative to carbon-intensive cement production. Although earlier studies have reported the potential of palm oil fuel ash as a pozzolan, its industrial acceptance is highly limited. The present review focuses on a critical comparison of palm oil fuel ash blended concrete with fly ash or slag based blended concretes which are widely accepted. Fresh, hardened and durability characteristics of blended concretes are meticulously compared. The addition of fly ash and palm oil fuel ash enhances the workability of concrete, whereas the addition of slag reduces the workability of concrete. At a replacement level of 60%, POFA blended concrete exhibited an increase in slump value of 21% as compared to the control concrete. All the three pozzolans exhibited lower earlier strength owing to their slower rate of reaction. The optimum replacement levels of palm oil fuel ash, fly ash and slag are 10%, 30% and 40%, respectively. For a constant replacement level (20%), the reduction in the water absorption as compared to the control concrete was 26.5%, 26.73% and 26.2% for POFA, fly ash and slag blended concrete, correspondingly. Chloride penetration and water absorption are lesser for all blended concretes than the control concrete up to their optimum replacement levels.