Corrosion/Degradation Monitoring Technology for Composite Materials used to Extend Building Service Life

Fiber-reinforced polymer (FRP) composites offer cost and performance advantages for patching concrete structures that have corroded reinforcing steel, but the Army largely avoids structural composite repair applications because of the lack of long-term performance data. Established composite patch inspection methods are fast but highly subjective. This report describes the demonstration of acoustic guided wave (AGW) technology as a nondestructive evaluation (NDE) methodology for assessing the condition of FRP composite structural patches. The technology uses a hand-guided rolling probe to collect ultrasonic inspection data that can then be analyzed to determine patch condition. The technology was used to evaluate more than 250 composite seismic upgrade patches installed in 1999 at historic Michie Stadium, U.S. Military Academy. The amplitude difference between the probe s emitted signal and the measured reflection provides data about bond quality and potential material defects. The technology identified five patches needing follow-up attention and possible rehabilitation. When considering costs for equipment procurement, logistics, labor, and field contingencies, an average patch-inspection time of 1.5 hours was estimated. The calculated life-cycle return on investment for this application was 11.91. The original document contains color images. Prepared in collaboration with Mandaree Enterprise Corporation, Warner Robins, GA, and Physical Acoustic Corporation, Princeton Junction, NJ.