Enhancing Sustainable Construction Practices: Utilizing Heat-Treated Recycled Concrete Fines for Improving Slag-Based Geopolymer Materials

This study explores the untapped potential of utilizing heat-treated recycled fines (HT-RFs) from mortar as a sustainable and eco-friendly alternative for slag-based geopolymer materials in construction. The RFs undergo a novel heat treatment process at 650 °C to significantly enhance their reactivity. Geopolymer mixtures incorporating both heat-treated and untreated RFs at various replacement ratios (0%, 10%, 20%, and 30%) are meticulously evaluated for their porosity, flexural strength, and compressive strength after 28 days of curing. The load-midspan displacement and failure behavior are analyzed using digital image correlation techniques. The microstructure of the mortar samples is comprehensively analyzed using state-of-the-art techniques including thermogravimetry, scanning electron microscopy, and X-ray diffraction. The results showed that the incorporation of 30% heat-treated recycled fines into slag based geopolymer increased compressive and flexural strengths by 30.67% and 27.31%, respectively, while substantially reducing the porosity by 16%, compared to the control geopolymer mixture. This study promotes sustainability in construction with eco-friendly materials by minimizing waste.