Virtual Edge Extension Technique to Reduce the Edge Effect in Impact-Echo Method

Abstract

The impact-echo method is a popular non-destructive testing method in civil engineering. The present work proposes the virtual edge extension technique to overcome the edge effect, which is a major issue during impact-echo testing. The virtual edge extension technique utilizes wave energy absorbing mediums (e.g., water) temporarily brought in contact with the concrete edges to mitigate the misleading signal clutter. In order to conduct this study, an instrument called constant amplitude impactor has been developed to produce constant source waves to facilitate comparison of wave characteristics. The effectiveness of the wave attenuation/absorbing characteristics of four different mediums have been investigated in the present work. It has been demonstrated that the depth could be evaluated from noisy signals and smaller defects (of size 20 at 100 mm depth) could be identified in concrete blocks. Encouraging results indicate that the virtual edge extension technique is useful in improving the non-destructive evaluation using impact-echo method.