Mechanical properties, high temperature resistance and microstructure of eco-friendly ultra-high performance geopolymer concrete: Role of ceramic waste addition

This study aims to develop ultra-high performance geopolymer concrete (UHPGC) using fine ceramic waste (FCW) as a partial fine aggregate. In this research, 12 mixes were designed, prepared, and tested to evaluate the influence of ceramic waste as a partial replacement of fine aggregate up to 22.5% on the performance of UHPGC. The fresh properties, mechanical properties, durability, and high temperature resistance of the developed ma-terial were investigated. The ecological assessment of UHPGC incorporating FCW has also been analyzed via life cycle assessment. The experimental results showed that the incorporation of FCW accelerates the setting time and reduces the slump of the fresh concrete. For hardened concrete, it has a relatively negative effect on mechanical properties to a certain extent. The compressive strength decreased to 123 MPa with the incorporation of 22.5% FCW. However, with smaller replacement percentages, 7.5 and 15%, the concrete exhibited better strength than 22.5%. This reduction may be attributable to the lower bond between the geopolymer gel and the ceramic particles. It was additionally found that the UHPGC's sorptivity increased simultaneously with increasing FCW content. For, high temperature resistance, inclusion of fine ceramic waste showed enhancement of residual strength as compared to the control mix after 700 ?C exposures. A microscopic investigation showed that samples utilizing ceramic aggregate had fewer micropores and cracks after being subjected to high temperatures. Besides, TGA analysis revealed that mixtures using FCW were more stable up to 650 ?C. Finally, using FCW can reduce carbon emissions and energy consumption to acceptable levels of 267 kg CO2eq/t and 571 MJ/m3, respectively, with low economic targets. Based on the obtained results, ceramic waste can be optimized and exploited as potential sources for manufacturing eco-friendly UHPGC with improved resistance to high temperatures and minimum harmful effects on mechanical properties and durability.