Abstract
Reinforced concrete (RC) has been widely used in construction due to its high availability and low cost. RC structures, however, present many durability issues that can introduce high maintenance costs and reduce their service life. This is especially true for structures located near salt water or exposed to deicing salts, as they are highly prone to corrosion. Driven by the need to eliminate corrosion, fiber-reinforced polymer (FRP) reinforcement has been gaining acceptance as an alternative to steel reinforcement. The application of FRP reinforcement is ideal for the current time, in which there is a need to rehabilitate deteriorated RC structures and to rebuild shoreline protection structures to adapt to climate changes (such as sea-level rise and higher storm intensity). The use of this material as an alternative to steel aims to create structures that are more durable and sustainable, and most importantly, resilient.
To advance the widespread use of FRP reinforcement, however, additional research is needed to ensure its safe application. Durability studies and the development of design and construction guidelines, particularly for industry professionals, are some of the barriers still faced by FRP reinforcement. With the objective to collaborate on on-going research on FRP reinforcement, this dissertation addresses different aspects of FRP as an internal reinforcement. The studies herein include innovative field deployment, investigation, and generation of new information on FRP reinforcement.
This dissertation includes three studies with the overall goal of presenting FRP reinforcement as an alternative to steel to create resilient concrete structures. The first study addresses design and construction methods while demonstrating field applications of glass FRP and basalt FRP bars to build a resilient structure. It also implements Accelerate Bridge Construction (ABC) to a coastal structure and uses sustainable concrete with seawater. The second study provides new information on the long-term durability of in-service GFRP bars. The investigated bars were extracted from bridge decks and other locations from eleven bridges exposed to freeze-thaw cycles and deicing salts. The extracted bars had been in service for 15 to 20 years and are part of one of the first applications of GFRP bars in civil infrastructures in the U.S. The conditions of the investigated extracted bars and their surrounding concrete presented minimal degradation. The tensile strength of the extracted bars was calculated to have reduced by 2.17% over 17 years. No apparent sign of chemical degradation was observed, and environmental damage observed in the microstructure of the bars has negligible impact on mechanical properties.
The third study experimentally investigated the bond coefficient, kb, of a helically grooved GFRP bar and compared it with a GFRP bar made of sand-coated with helical wrap surface, and with traditional steel bar. The kb of the helically grooved GFRP bar was approximately 11% higher than the sand-coated bar but lower (better) than the recommended value by current design guidelines. This study also presented observations and recommendations to help improve the current experimental test method to determine kb. Overall, this dissertation presented contributions to different aspects of on-going research on FRP reinforcement. The studies presented here provide opportunities for future research and positive indication of the application of FRP reinforcement towards creating resilient concrete structures.