Accelerated testing for bond reliability of fiber-reinforced polymers (FRP) to concrete and steel in aggressive environments

The contents of this dissertation present five submitted journal papers corresponding to experiments and prediction analysis of the bonding characteristics of fiber-reinforced-polymers (FRP) to concrete and steel. The papers are submitted to the American Society of Civil Engineers (ASCE) Journal of Structural Engineering and the American Concrete Institute (ACI) Journal of Composites for Construction.; The first paper provides the background on the importance of resin systems in composites, particularly, for retrofitting and rehabilitating of existing structures. The paper provides a general understanding of the structure and important characteristics of epoxies for civil engineers involved in research and the application of FRP in construction. This paper also presents an overview of studies conducted on the durability of epoxy bonded joints in moist environments.; The second and third paper provide the results of a comprehensive study on evaluation of bond strength of fiber-reinforced-plastics (FRP) to concrete and steel in simulated aggressive environments. The severity of bond deterioration varies in different environments and is quantified in this study. Fracture toughness is evaluated at the initiation of cracking and during the propagation of cracking. The environments consist of high temperature (120°F), acidic (pH = 3), alkaline (pH = 12), seawater (pH = 8.3), and high humidity <100%. The experiments consist of testing in shear 728 unidirectional carbon FRP coupons bonded to concrete and steel blocks. The lap shear tests evaluate the bond strength and fracture toughness of the FRP/substrate interface as related to different exposure times in different environments.; The last two papers focus on accelerated degradation testing techniques, and discuss the lifetime prediction on the bond of carbon (FRP) to concrete and steel. Fick's law of diffusion is used to model the moisture penetrating through the FRP and into the bonded joint. A reliability analysis is developed to predict the fracture toughness at any relative humidity and temperature, based on the 100% relative humidity conditions at ambient temperature. The results in this study generally show an excellent durability for the FRP bonded to either concrete or steel, even in the most severe environments.