Development of Ultra-High Performance Geopolymer Concrete Containing Recycled Fine Aggregate Replacement

Abstract

The construction industry continually strives to enhance sustainability and reduce environmental impact. Developing innovative concrete materials that utilize recycled aggregates and alternative cementitious binders has gained significant attention in this context. This abstract presents a study on developing ultra-high-performance geopolymer concrete (UHPGC) by replacing fine aggregates with recycled materials. This research aims to develop UHPGC by incorporating recycled fine aggregate waste (RFAW) as a partial replacement for fine aggregate. Four different concrete mixes were prepared and tested to evaluate RFAW's influence on the performance of UHPGC, considering replacements of up to 30% of fine aggregate. The study examined the fresh properties and mechanical characteristics of the resulting material. The experimental outcomes demonstrated that adding RFAW enhanced the workability of fresh concrete, making it more easily manageable. However, the mechanical properties of the hardened concrete were slightly affected to some extent. Specifically, the compressive strength decreased from 119 MPa to 103 MPa when 30% RAW was added. Conversely, with lower replacement percentages of 10% and 20%, the concrete exhibited no reduction in strength compared to the 30% replacement levels. This reduction in strength could be attributed to a weaker bond between the geopolymer gel and the recycled fine aggregate particles. Additionally, it was observed that as the proportion of RFAW increased, the water absorption of the UHPGC also increased. This indicates that the concrete had a higher tendency to absorb moisture. Nevertheless, the findings suggest that RFAW waste could be a viable resource for producing environmentally friendly UHPGC with improved physical, mechanical, and durability properties with appropriate optimization. The outcomes of this study can promote sustainable construction practices by reducing the reliance on virgin materials and promoting the circular economy within the civil engineering industry.