Nondestructive assessment of microcracks detection in cementitious materials based on nonlinear ultrasonic modulation technique

Abstract

The generation and expansion of concrete microcracks have a significant influence on the durability of special concrete structures such as nuclear power plants and reservoirs. Based on the theory of nonlinear ultrasonic modulation, the edge-band peak counting method and the concept of damage index (DI) are proposed to evaluate the development of concrete microcracks. The cementitious materials specimens with different damage degrees can be obtained by alkali-aggregate reaction, and the results of cumulative and continuous micro damages in concrete specimens show that the DI increases with the development of microcracks, which is consistent with the theoretical research. The peak value of DI increases with a higher water-cement ratio in an appropriate range, indicating a higher alkali-aggregate reaction degree. The nonlinear ultrasonic modulation method could be a good indicator of the damage in cementitious material structures.