Effect of recycled clay brick aggregates on the residual properties of concrete after exposure to elevated temperatures

The reuse of crushed clay bricks as coarse (CCCA) and fine (CCFA) aggregates provides an eco-friendly alternative to natural aggregates and a sustainable solution for construction waste. This study evaluated the residual properties of concrete incorporating CCCA and CCFA at 0%, 25%, 50%, 75%, and 100% replacement levels after exposure to elevated temperatures (200–800 °C). Ten concrete mixes were tested for weight loss, water absorption, sorptivity, compressive, splitting tensile, and flexural strengths, abrasion and impact resistance, ultrasonic pulse velocity, and Schmidt rebound number. Elevated temperatures caused mass loss, increased water absorption and sorptivity, reduced mechanical strengths, and degraded impact and rebound performance, particularly beyond 400 °C. While replacing natural aggregates with CCCA/CCFA slightly reduced initial performance, it improved strength retention at high temperatures, with CCFA generally performing better than CCCA. The findings highlight a tradeoff between sustainability and mechanical performance.