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Advances in Civil Engineering
Volume 2010, Article ID 238472, 8 pages
http://dx.doi.org/10.1155/2010/238472
Research Article

Potential of Nonlinear Ultrasonic Indicators for Nondestructive Testing of Concrete

Laboratoire de Caractérisation Non Destructive, Université de la Méditerranée, IUT Aix-Provence, Avenue Gaston Berger, 13625 Aix-en-Provence Cedex, France

Received 7 October 2009; Revised 15 February 2010; Accepted 14 April 2010

Academic Editor: Patrice Rivard

Copyright © 2010 C. Payan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In the context of a growing need for safety and reliability in Civil Engineering, acoustic methods of nondestructive testing provide answers to a real industrial need. Linear indicators (wave speed and attenuation) exhibit a limited sensitivity, unlike nonlinear ones which usually have a far greater dynamic range. This paper illustrates the potential of these indicators, and evaluates its potential for in situ applications. Concrete, a structurally heterogeneous and volumetrically, mechanically damaged material, is an example of a class of materials that exhibit strong multiple scattering as well as significant elastic nonlinear response. In the context of stress monitoring in pre-stressed structures, we show that intense scattering can be applied to robustly determine velocity changes at progressively increasing applied stress using coda wave interferometry and thereby extract nonlinear coefficients. In a second part, we demonstrate the high sensitivity of nonlinear parameters to thermal damage as regard with linear ones. Then, the influence of water content and porosity on these indicators is quantified allowing to uncouple the effect of damage from environmental or structural parameters.