Stress–strain relationship of coarse RCA concrete exposed to elevated temperatures

An investigation was carried out on the complete compressive stress–strain curves of concrete made with coarse recycled concrete aggregate (RCA) after exposure to temperatures of 20–800°C. In total, 75 prism specimens of five different compositions were made with replacement percentages of 0, 25, 50, 75 and 100% coarse RCA. Specimens were exposed to preset temperatures for 3 h in separate batches and were tested 1 month after heating. The residual compressive properties, including compressive strength, modulus of elasticity, peak strain and complete compressive stress–strain curves, were obtained from the tests. The experimental results demonstrate that both the compressive strength and modulus of elasticity of coarse RCA concrete decrease continuously with increasing temperature, whereas the peak strain increases rapidly. The replacement percentage was found to have insignificant influence on the relative deterioration of exposed coarse RCA concrete compared with unexposed concrete. A stress–strain model was developed for predicting the compressive stress–strain relationship of coarse RCA concrete after exposure.