These inspection guidelines (NCHRP Report 848)
describe NDE methods for different condition assessment including corrosion, section loss, breakage, grout conditions, voids, water infiltration, and tendon deterioration in the anchorage systems. The NDE methods are Ground Penetrating Radar (GPR), Infrared Thermography (IRT), Electrical Capacitance Tomography (ECT), Magnetic Flux Leakage (MFL), Magnetic Main Flux Method (MMFM), Impact Echo (IE), Ultrasonic Tomography (UST), Ultrasonic Echo (USE), Sonic/Ultrasonic Pulse Velocity (S/UPV), Low Frequency Ultrasound (LFUT), Sounding, Visual Testing (VT), and Electrochemical Impedance Spectroscopy (EIS). The material in this report will be of immediate interest to bridge owners and inspectors.
Visual bridge inspection of post-tensioning and stay cable systems is difficult because tendons are typically embedded in massive concrete (internal tendons) or opaque ducts (external tendons or stay cables). The current state of non-destructive evaluation (NDE) technology has limitations for evaluating the condition of bridge post-tensioning and stay cable systems for corrosion, section loss, breakage, grout conditions, voids, water infiltration, and tendon deterioration in the anchorage systems.
In recent year, technologies and innovative applications have continued used in other industries may have potential for bridge condition assessments, and NDE technologies applied in combination may also provide opportunities not yet realized.
Corrosion, section loss, and breakage have impacts in the form of reduced safety and load capacity, costly rehabilitation actions, and traffic disruption. Condition assessment of post-tensioning and stay cable systems could allow bridge owners to take timely, proactive actions to mitigate or prevent further deterioration and unanticipated failure. The population of structures containing post-tensioning and stay cable systems continues to grow and age. Therefore, the condition assessment of these systems is critical for maintaining public safety.
Research was performed under NCHRP Project 14-28 by the Texas A&M Transportation Institute to develop inspection guidelines to assist bridge owners in selecting the most appropriate NDE method for assessing the condition of in-service post-tensioning and stay-cable systems.
The research agency’s final report that documents the entire research effort is available at: