Nondestructive evaluation of concrete dams and other structures

This paper presents an overview of several stress-wave based nondestructive testing methods which can be used to assess the condition of concrete structures such as dams, buildings, and foundations. The specific methods to be presented include the use of the impact echo (IE) and spectral analysis of surface waves (SASW) methods in the assessment of dam concrete condition (including freeze-thaw damage assessment), the use of ultrasonic pulse velocity tomography (UPV tomography) in the 2 dimensional imaging of concrete defects in walls and foundations, and the use of the crosshole sonic logging (CSL) method for rapid, accurate, and cost-effective quality assurance of drilled shaft foundations. Included in this paper are summary descriptions of each of the NDT methods used (including some underlying theory), along with brief case histories of the application of each of these methods to real-world problems. Case histories presented include the evaluation of the Rogers' Dam spillway for freeze-thaw damage and overall concrete condition, the use of the CSL method in quality assurance testing of foundations for the LA Metro Green Line, and the use of tomography for imaging a defect in a deep foundation.