Experimental Research on Elastic Modulus and Compressive Strength of High-Strength Concrete after Fire

The bottom surface of the bridge beam, which is made of C50 high-strength concrete, is heated to 800°C in fire-resistant experiment. Then the elastic modulus and strength of the concrete are measured by the rebound method and core sampling method, and the test results are used to validate the theoretical methods. The study shows that the strength and elastic modulus of concrete decrease with the increasing of temperature. The strength from the current theoretical analysis agrees well with that from the experiment. But for the elastic modulus, there is a great difference between the theoretical and experimental analysis. The strength of the concrete after fire gotten from the rebound method has a bigger error than that from the core sampling method, so that the core sampling method should be used in preference.