Fundamental Study of Detecting Internal Defect in Building Materials Using High-Intensity Aerial Ultrasonic Waves with Finite Amplitude

An impact acoustic method and an infrared method are often used to detect peeling in building materials such as concrete and tile. However, both of these methods are susceptible to human error and require long measurement times. In this study, we examine a new method that uses high-intensity aerial ultrasonic waves to detect peeling in building materials. Specifically, we have developed a noncontact method of detecting defects in building materials by analyzing the vibration of an object excited with high-intensity aerial ultrasonic waves of finite amplitude at a frequency of 26.8 kHz. We prepared artificial peeling samples consisting of tile and concrete plates. The results indicated that there is clearly a large difference in vibration velocity and distortion rate between the area with artificial peeling and the area without peeling. Therefore, it is possible to detect peeling of building materials by this method.