Specific Durability Issues

A primary advantage of fiber reinforced polymer (FRP) reinforcing bars, rods, tendons, and grids for use as internal reinforcement for concrete structural elements is their inherent resistance to electrochemical corrosion. Indeed, corrosion of conventional steel reinforcement in concrete structures is one of the key factors responsible for the widespread deterioration of infrastructure currently evident around the world, and FRPs are now seen as promising materials in helping to address this daunting problem. However, FRP-reinforcing bars in concrete are not immune to long-term degradation—they are susceptible to varying degrees of physical and mechanical damage in the presence of assorted harmful environments and chemicals. It is, thus, essential when contemplating the use of FRP reinforcement in any specific concrete-reinforcing application to remain cognizant of the potentially damaging effects that might arise from exposure to moisture, high temperatures, low temperatures, thermal cycling, alkaline, acidic, saline, or otherwise harmful solutions, cyclic loading, sustained loading, and ultraviolet radiation. Because the term “durability” is not easily defined, in this chapter it is defined as the ability of an FRP element to resist cracking, oxidation, chemical degradation, delamination, wear, and/or the effects of foreign object damage for a specified period of time, under the appropriate load conditions, under specified environmental conditions