Durability of Adhesively Bonded FRP-to-Concrete Joints

Abstract

The adhesive bonding of fiber-reinforced polymers (FRP) to tensile faces of reinforced concrete elements is now widely considered as a simple and effective means for enhancing load-carrying capacity and decreasing deflection. There is, however, uncertainty surrounding the long-term durability of the FRP-to-concrete bonded system. Hence, a comprehensive database of available shear bond tests is collated, categorized, and analyzed to quantitatively assess the impact of environmental exposure on debonding failure modes, bond properties, and residual strength. Trends reveal that the durability of joints is generally not attributable to the type of fiber, strengthening scheme, surface preparation method, or differences in conditioning regimes, but rather the strong influence is by the durability of the adhesive layer. Significantly, deterioration of the adhesive layer alters the mechanical behavior of the joint, often to an extent where tests can fail to capture the full strain development along the bonded length, and therefore not fulfill the intended purpose of simulating crack-induced debonding failures in flexural elements. These findings allow for the development of regression models that predict the degradation of bond strength in FRP-to-concrete joints under a number of environmental conditions.