Preliminary fatigue tests on concrete after exposure to temperature of up to 300°C

Micro-cracks in the vicinity of paste-aggregate interfaces and in the paste itself can be induced when concrete is exposed to elevated temperatures in the range 100°C-300°C. Although with increase of temperature, the strength of concrete becomes more and more influenced by the growing number of micro-cracks, the compressive strength of concrete at an elevated temperature lower than 300°C is almost the same of concrete at room temperature. Under repeated load, those microcracks caused by temperature would propagate, enlarge and become linked up, as a result, the fatigue behavior of concrete would decrease. In this paper, tests have been carried out to study the fatigue behavior of concrete after exposure to elevated temperatures of up to 300°C. Test results have shown that the reduction of fatigue strength of concrete is remarkable.