Mechanical properties of concrete subjected to cyclic thermal loading

Abstract

This paper studies the effect of thermal cyclic loading on the mechanical properties of concrete such as cylinder and cube compressive strength, splitting and flexural tensile strengths, and weight loss. The specimens were exposed to 7–28 thermal cycles with peak temperatures of 100, 200 and 300 °C. A total of 120 specimens consisting of cubes, cylinders and prisms were tested in this study. The compressive strength of concrete enhances up to 7 or 14 thermal cycles and subsequently decreases but remains greater than the strength at ambient temperature at all temperature levels. The test results highlight the difference in compression behaviour of concrete cylinders and cubes. The effect of thermal cycles on splitting tensile strength of concrete is more pronounced than its effect on the modulus of rupture. Although the splitting tensile of concrete decreases with rise in the peak temperature and number of thermal cycles, the modulus of rupture increases up to seven cycles for exposure to the temperature cycles of 100 and 200 °C, which is even higher than the control. Models are developed to predict residual mechanical properties of concrete after exposure to the thermal cycles, which show close conformance with experiments.