Improving self-compacting concrete performance at high temperature with red ceramic waste filler

The high content of fine materials required in self-compacting concrete to ensure flowability reduces matrix porosity, thereby increasing vulnerability to deterioration and heat-induced spalling at high temperatures. This paper investigates the unconventional use of red ceramic waste as a replacement for limestone filler in self-compacting concrete, leveraging its porous structure to attenuate thermo-hydro-mechanical effects and mitigate heat-induced spalling. Residual compressive strength, modulus of elasticity, mass loss, homogeneity, capillary absorption, and evidence of heat-induced spalling were monitored in conventional and self-compacting concrete conditioned specimens after exposure to temperatures ranging from 200 °C to 800 °C at 1 °C/min. Heat-induced spalling was simulated by subjecting unconditioned specimens to a high heating rate to 1000 °C at 27 °C/min, thereby replicating severe thermal loading conditions. The self-compacting mixture with red ceramic waste fulfilled flowability and stability requirements at the fresh state. Replacing limestone filler with red ceramic waste enhanced residual mechanical performance, particularly in the 200 °C to 600 °C range, highlighting the beneficial role of the waste’s porous structure in mitigating thermo-hydro-mechanical damage. Although incorporating red ceramic waste did not entirely prevent heat-induced spalling at a high heating rate, it significantly reduced damage severity compared to limestone filler. Furthermore, self-compacting mixtures with red ceramic waste as a filler required 3% (C30) to 10% (C40) less cement, offering a potential reduction in the concrete carbon footprint and contributing to circular economy principles through the valorization of industrial waste.