For over 25 years, fiber reinforced polymer (FRP) composites have been in-service as wraps for columns and beams, rebars in concrete and also as bridge decks for highway and other structural applications. For example, a large number of pedestrian and vehicular bridges have been built across the country using FRP composite materials as rebars, decks and even as superstructures. In addition, many concrete and timber bridges have been rehabilitated using FRP composite wraps, in addition to occasional repair of steel bridges. Although few in-service FRP structures presented problems, most have been performing well. The proposed effort is to determine the in-service performance status of existing FRP structures and assess their durability under a wide range of service and environmental conditions including moisture ingress, pH variations, sustained stresses, fracture and thermal fatigue, by conducting nondestructive evaluation and load tests, and harvesting coupons from field samples where possible.

Determine the conditions of existing in-service FRP highway structures through nondestructive testing and in-situ load testing. Evaluate durability of FRP structures and wraps by collecting and testing coupon size samples from the in-service structural components to arrive at design related strength reduction factors under natural aging.

The proposed work will include the following tasks: 1. Nondestructively assess conditions of several existing in-service FRP highway structures including joints using infrared thermography, ground penetrating radar, digital tap meter, pachometer, resistivity and corrosion potential measurement device in addition to in-situ load testing with focus on failure types (if any) in terms debond, delamination, stress concentration, fracture and fatigue, excess deflection, vibration, and others. 2. Collect coupon size field samples at both critical and non-critical locations from in-service FRP structures. 3. Test field samples of Task 2 under tension, bending, shear, DMTA, DSC, and SEM for material properties and void content as per applicable ASTM standards to determine material property reductions. 4. Compare the data obtained from Task 3 with the available data from state DOTs at the time of installation accounting for environmental conditions, traffic patterns (ADT, ADTT), material compositions (resin type, fiber volume fraction etc.) and manufacturing methods. 5. Generate additional lab-accelerated aging data (if control samples are available) in a limited manner and correlate the results with available lab and field data from in-service FRP composite bridge structures to better understand degradation mechanisms before developing predictive models. 6. Discuss degradation mechanisms of FRP composites for material improvements for highway structural applications in terms of resin enbrittlement, resin oxidation (UV), resin hydrolysis, delamination/debond at fiber/matrix interface, fiber breakage etc. 7. Determine material strength reduction factors from the data and evaluations of Tasks 3, 4, 5, and 6 for design of FRP structures, where possible (i.e. enough data are available). 8. Conduct a workshop to disseminate the research findings among interested parties, which includes design examples, design details, construction details, and field demonstrations.

Participation level is requested to be $20,000 per year. SP&R Approval Waivers are being submitted for approval.