Rotary Hammering Condition for Defect Detection of Concrete Structures

Abstract

Hammering test using the inspection hammer is most commonly used to evaluate the defects of concrete structures because it is relatively simple. This method depends on the subjective sense of inspectors to detect defective parts. In this study, we adopt a hammering method using the rotary hammering device to improve inspection efficiency. We move the rotary hammering device along the concrete surface and measure the impact sound near the surface with the microphone attached to the device. The sound characteristics measured from healthy parts and defective parts for four types of defective depth are compared in the time and frequency domain. The time waveforms indicate the sound pressures for the defective parts are apparently higher than those for the healthy parts when the pressing force applied to the rotary hammering device is appropriate. The frequency spectrum indicate the peak frequency of the sound pressure increases and its amplitude decreases with the defective depth.