Comparative assessment of the effects of furnace bottom ash and fly ash on mortar performance

School of Architecture and Built Environment, University of Newcastle Newcastle, Australia

^* Corresponding author: Ali.Onaizi@uon.edu.au

Abstract

The increased reuse and recycling of industrial waste could significantly reduce resource footprint and greenhouse gas emissions. Furnace bottom ash (FBA) is a by-product of thermal power plants and recycling it in the construction industry could have substantial environmental and economic benefits. This study aimed to compare FBA-based mortar with that of FA as a partial substitute for cement in the production of sustainable mortar. Three mixtures with 10%, 20%, and 30% FBA were created, and their workability, compressive strength, and water absorption properties were examined. The workability of the mixtures decreased with an increase in the FBA percentage. The compressive strength of the FBA-containing mixtures was similar to the control mix at early ages, but as curing time increased, the strength of FBA-containing mortars increased considerably due to pozzolanic reactivity. Additionally, the FBA-containing mixes had lower water absorption than those containing fly ash (FA) and the control mixture. As the proportion of FBA in the mixture increased, the amount of water absorbed by the mortar cube decreased. The findings proposed that 10% is the optimal proportion of FBA to substitute cement, as it showed a comparable compressive strength to the control mixture at 7 and 28 days and surpassed the strength of the control sample by 14% after 56 days. This work is anticipated to pave the way to foster new research opportunities by enabling detailed comparisons between emerging and standardized cementitious materials. It will help minimize performance uncertainties and assist in incorporating emerging materials into those standards, enhancing their overall applicability and reliability.