Residual compressive stress-strain relation of recycled aggregate concrete after exposure to high temperatures

The complete compressive stress-strain curve of recycled aggregate concrete (RC) after exposure to high temperatures improves to assess the post-fire behavior of reinforced RC structures. In this paper, 60 specimens containing different levels of recycled coarse aggregate (RCA; i.e., 0, 30, 50, 70 and 100%) were produced to study the residual compressive stress-strain relation of RC after exposure to high temperatures. Those specimens designed for thermal temperatures were initially heated to temperatures of 300, 400 and 500°C for 6 hr and then being submitted to test the compressive stress-strain curves after cooling to ambient temperature. The test results were compared with specimens tested at room temperature (about 20°C). The effect of RCA and high temperatures on residual compressive strength, peak strain and elastic modulus are discussed and the empirical formulas for these parameters are also established. The recommended equation for the compressive constitutive relation for conventional concrete in the Chinese code for the design of concrete structures (GB50010-2010) was adopted to fit the test data and was shown to be applicable to heated RC for different temperatures.