Experimental study of Portland cement concrete performance at moderately-elevated temperature

Concrete, as the most commonly-used construction materials, is used for thousands of structures, including buildings in nuclear power plants. Some concrete structures in nuclear power plants are subjected to moderately elevated temperatures, typically less than 200 °C when operating, but a high-temperature environment can cause degradation of structures. Thus, it is essential to understand the performance of concrete affected by elevated temperature during service life. The concrete high-temperature behavior was explored by conducting mechanical properties tests, permeability test and microstructural test on concrete heated at 65–200 °C for 56 days, and was compared to the identical concrete performance at room temperature. The results show that the moderately-elevated temperature had less impact on concrete compressive and tensile behaviors, but dramatically lowered concrete modulus of elasticity and resistance to chloride penetration. The microstructural change of concrete dominated the performance change of concrete exposed to elevated temperature. Based on experimental results, the long-term performance of concrete in a moderately-elevated temperature environment is predicted.