Non-Destructive Testing of Bar or Cable Anchors Embedded in Concrete Dams

Feasibility Analysis of Reflectometry for Dam Support Non-Destructive Evaluation. Concrete dams and other large civil structures utilize steel cable anchors to improve strength and stability. These anchors are imbedded in concrete and may deteriorate over time, resulting in complete or partial breakage. Reflectometry methods that have been used for location of faults in electrical systems are examined as a possible method for location and quantization of faults on concrete anchors. This project examined through simulation and simple measurements the feasibility of using reflectometry (either in the time or frequency domain) for fault location on concrete anchors.
T052700-0208A/2 — Electrical Testing of Concrete Dam Effects—Reports on Simulation, Testing at the US Bureau of Reclamation. This report presents the results of a series of tests undertaken at the US Bureau of Reclamation test site in Denver, CO, on July 21, 2005. The purpose of this testing was to prepare for upcoming testing at the Mactaquac Dam for Project T052700-0208B and to answer several questions about electrical testing of concrete anchors which remained after simulation and basic lab testing at the University of Utah for Project T052700-0208A. A seven-strand cable was placed on the floor, with the strands short circuited together at both ends. One or more strands of the cable were cut in several different locations to determine the ability of reflectometry to locate these faults. This report discusses the actual variation of concrete parameters along the length of a test cable, the measured attenuation observed in the Time Domain Reflectometry (TDR) signal over 100’ in air, and the relationship between simulations and measurements.
T052700-0208B — Reflectometry Testing for Dam Anchors (Mactaquac Testing). This report describes testing of anchors at Mactaquac Dam, New Brunswick. Initially the intention was to validate the feasibility of reflectometry methods for location of broken strands; however, testing demonstrated that the anchor cables are not electrically isolated as originally expected, and as required for electrical testing. Methods to isolate the cables, connect to them for long term monitoring, and test them are described.
T062700-0208C — STDR Testing of Tendon in Concrete Beam (USBR Testing). This report describes Spectral Time Domain Reflectometry (STDR) testing of metal rods in a concrete beam at the Bureau of Reclamation, Denver, Colorado, Feb 7, 2006. The purpose of this test was to verify that STDR is able to see and locate the end of a wire imbedded in concrete. The STDR method, the connectivity methods, and the test data described.