On the accuracy of thickness measurements in impact-echo testing of finite concrete specimens--numerical and experimental results.

In impact-echo testing of finite concrete structures, reflections of Rayleigh and body waves from lateral boundaries significantly affect time-domain signals and spectra. In the present paper we demonstrate by numerical simulations and experimental measurements at a concrete specimen that these reflections can lead to systematic errors in thickness determination. These effects depend not only on the dimensions of the specimen, but also on the location of the actual measuring point and on the duration of the detected time-domain signal.