Effects of Poisson's Ratio on Impact-Echo Test Analysis

Abstract

Although the Poisson's ratio of concrete is known to vary within a significant range of values, the resulting effects on impact-echo test results have not been studied. In this regard, background to the problem is given followed by an introduction to the impact-echo test technique. An exact analysis model for impact-echo data, guided-wave analysis (GWA), based on elastic guided wave-propagation theory is introduced and experimentally demonstrated to be a powerful alternative to the existing impact-echo analysis model (IEM). It is shown that the IEM model cannot account for changing values of the material Poisson's ratio, whereas the new GWA model can. Relationships among the Poisson's ratio, shear-wave velocity, and longitudinal-wave velocity of a material and the associated impact-echo test results are developed through the use of the GWA model. This development involves a parametric investigation of predicted impact-echo test results for solidand hollow-rod structures. The significant effect of Poisson's ratio as well as longitudinaland shear-wave velocity on such impact-echo results is demonstrated, and directions for future work are suggested. Conclusions concerning the validity of the GWA and IEM models and the significance of IEM analysis errors, owing to the disregard of Poisson's ratio as a significant factor, are given.