مهدی نعمت زاده افروزی

An efficient technique to recycle crumb rubber is to use it in concrete. The general stress-strain relationship for the concrete exposed to fire is required to provide specific fire-performance criteria for designing concrete structures. In this research, the residual stress-strain behavior of concrete containing crumb rubber as a natural sand replacement (by 0, 15, and 30%) under axial compression after exposure to elevated temperature (200, 400, 600, and 800 °C) was studied. For this purpose, the physicomechanical properties of the concrete specimens including compressive strength, tensile strength, modulus of elasticity, strain at peak stress, ultimate strain, toughness, stress-strain curve, and weight loss as well as their visual characteristics were examined after thermal exposure, and a number of empirical models were then proposed for the prediction of mechanical properties. Furthermore, a comparison was conducted between the experimental results and the prediction results of the ACI 216, EN 1994-1-2, ASCE, EN 1992-1-2, and CEB-FIP 1990 codes. Finally, using the empirical equations obtained for the mechanical properties, a stress-strain model was developed to predict the compressive performance of concrete containing crumb rubber under elevated temperatures, which demonstrated a good agreement with the experimental results. The results showed a notable degradation of the physicomechanical properties of the specimens with temperature increase.