Damage and Defects in Fiber-Reinforced Polymer Reinforced and Strengthened Concrete Elements

Abstract

Fiber-reinforced polymer (FRP) composites are becoming increasingly popular as an alternative to conventional civil engineering materials in existing structures as externally applied systems for strengthening purposes, and in new structures as internal reinforcements in the form of bars, meshes, and strands. The next phase of development in the application of FRPs in concrete structures could culminate in elements possessing both internal and external FRP systems simultaneously. With these advancements in the application of FRP in civil engineering, it is conceivable that traditional steel reinforcements could become obsolete in certain aggressive and hostile environments, such as coastal areas. Although higher durability and performance are associated with FRP materials in some respects when compared to steel, concerns remain regarding the damage and defects in this material, many of them related to their unique features. Regardless, similarly to other structural materials, it is necessary to understand the damage and defects associated with the use of FRP composites, as well as to identify their sources. This knowledge will support the positive prospects for FRP technology, promoting its application in civil infrastructure. Accordingly, this study investigated the types, characteristics, and identification of the observed or expected damage and defects associated with using FRP in reinforced and strengthened concrete elements. The damage was classified according to location and time of initiation. In addition, the sources of these defects and damage were determined, and a damage etiology was established for preventing the occurrence of such damage in future use. The results of this study are intended to provide the background for the development of a guide and training material for the inspection of structures that use FRP materials. The ability to inspect and properly maintain structures containing FRP will result in the enhanced durability and service life of concrete structures reinforced or strengthened with FRP materials. With advancements in the application of fiber-reinforced polymer (FRP) in civil engineering and the development of practical means for its use in design and construction, it is conceivable that traditional steel reinforcements could become obsolete in certain aggressive and hostile environments, such as coastal areas. Although higher durability and performance is associated with FRP when compared to steel, concerns remain regarding the potential damage and defects that could be associated with its use. To help the owners of concrete structures feel comfortable with this relatively new application, guides and procedures are needed that will support the inspection and detection of potential damage in FRP. For this, it is necessary to understand the damage and defects that can occur in externally and internally applied FRP, and to be able to identify their sources. In this study, we investigated the types, characteristics, and identification of observed or expected damage and defects associated with using FRP in reinforced and strengthened concrete elements. In addition, the sources of these defects and damage were determined and a damage etiology established as a basis for developing a guide and training materials for the inspection of structures that use FRP materials. An accurate understanding of such damage and its sources could be used for maintenance and preventive measures for structures that were constructed using FRP materials.