Ultrasonic inspection of concrete subjected to triaxial compressive loading history

An experimental study of the confined compression behaviour of concrete has been performed using 100 mm concrete cubes. The compressive strength, splitting tensile strength and ultrasonic velocity are measured before and after loading history, respectively. Based on the continuum damage mechanics theory, the reduction of compressive strength and splitting tensile strength denote the damage of concrete. The relationship between the damage and the decrease of ultrasonic velocity owing to triaxial loading history is investigated. According to the fitting of experimental data, the evolution equation of damage is obtained. The damage is found to be in a linear dependence relationship with the decrease of ultrasonic velocity. It is concluded that, being an important non-destructive detection method, ultrasonic inspection is convenient and applicable to the estimation of the damage of concrete under various loading patterns in engineering practice.