Innovations for NDT of Concrete Structuresby Dennis A. Sack, Olson Engineering Inc, Golden, United States,
Larry D. Olson, Olson Engineering Inc, Golden, United States,
Gregory C. Phelps, Olson Engineering Inc, Golden, United States,
Abstract: The proposed paper presents three recent innovations for sonic and ultrasonic Non-Destructive Testing (NDT) of concrete structures which greatly increase the utility and speed of many NDT investigations. Of the three innovations, one allows the use of NDT to determine parameters previously unavailable, while the other two involve the use of scanning techniques to increase the speed of testing for two existing NDT techniques. The first innovation presented is the application of the Spectral Analysis of Surface Waves (SASW) technique to concrete structures. This method is particularly applicable to testing pavements, slabs, tunnels, shaft liners, and massive concrete structures such as dams and other installations where information on thick concrete or on concrete and the subsurface behind the concrete is required. The technology allows nondestructive determination of the shear wave velocities of the various components (including rock and soil layers) of a layered system while testing from only one surface. Included is an overview of the method and the principles behind it, as well as some case history examples. The next two innovations presented are related, in that they both allow rapid scanning techniques to be used during the performance of previously developed but relatively slow NDT methods. These scanning techniques are applied to both the Ultrasonic Pulse Velocity (UPV) and Impact Echo (IE) methods, which have both been traditionally performed on a point-by-point basis. This new technology allows the near-continuous acquisition of data along any given path over a structure. Included will be test data collected using the scanning systems to better illustrate their utility and to compare to data collected on a traditional point-by-point basis.
Subject Headings: Surface waves | Concrete slabs | Innovation | Ultrasonic methods | Concrete structures | Concrete pavements | Concrete dams | Wave velocity
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