Corrosion of prestressed concrete reinforcement in bridge components is a major concern for state transportation agencies. The severity of the problem is amplified by the fact that the corrosion-induced damage in concrete reinforcement often does not show up on the surface until significant propagation has occurred. Moreover, prestressed reinforcement can undergo brittle fracture at lower cross-sectional losses when compared to nonprestressed reinforcement. As evidence, some prestressed bridges in Virginia built since the 1960s have begun showing premature corrosion-induced deterioration. This created a need for a nondestructive evaluation technique that could reasonably determine areas of damage at early stages of corrosion.
Since a ready-to-implement commercial tool is not available, a prototype for a new magnetic flux leakage (MFL) device for the evaluation of hidden prestressing strand under the surface of prestressed concrete box beams was designed, developed, and tested in the laboratory. This device works based on the MFL principles of nondestructive evaluation. The novel features of this device are portability, lower cost, and real-time results, and it can be used by a bridge inspector with minimal training. The device uses advanced sensors and microcontroller technologies to deliver a battery-powered MFL inspection system device capable of detecting corrosion damage in prestressing strand beneath 2 in of concrete cover. This report can be downloaded from http://www.virginiadot.org/vtrc/main/online_reports/pdf/20-R14.pdf
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