Principal Investigator:	Ronald S. Harichandran
Research Assistant:	Victor Hong
Funding Agency:	Michigan Department of Transportation
Period:	February 2000 – August 2003

Abstract

Fiber reinforced polymer (FRP) materials are being used increasingly to retrofit concrete bridges and MDOT has implemented or will be implementing several field projects. Retrofits on beams, pier caps, and decks typically involve bonding of FRP to concrete, and integrity of the bond is crucial for success. Moisture and salt ingress into rehabilitated components has the potential to degrade the bond between FRP and concrete due to continued corrosion within the concrete or delamination of the FRP during freeze/thaw cycles. It is therefore important to develop a nondestructive evaluation method to monitor the integrity of the bond between FRP and concrete in rehabilitated structures.

Electrochemical Impedance Spectroscopy (EIS) is an established laboratory technique for the investigation of coating deterioration and substrate corrosion. Very good correlation has been reported between short-term EIS data (such as low frequency impedance) and long-term coating performance in sea water immersion or other exposures, demonstrating the technique’s predictive capabilities.

The proposed research will adapt existing EIS sensor technology developed by DACCO SCI, Inc., for use on bridge components rehabilitated with FRP. The objectives are to utilize the sensors to detect debonding of the FRP from the concrete substrate, and to ascertain that the sensors are durable under the environmental conditions in Michigan.



Resulting Publications

• Davis, G. D., Rich, M. J., Harichandran, R. S., Drzal, L. T., Mase, T., and Al-Ostaz, A. (2003). "Development of electochemical impedance sensor to monitor delamination and moisture uptake in CFRP-reinforced concrete structures." Proceedings, 81st Annual Meeting of the Transportation Research Board, Washington, D.C., Paper No. 03-2392.