Durability Evaluation of Carbon FRP/Concrete Shear Bond Strength

摘要

Synopsis: The bond between external fiber reinforced polymer (FRP) reinforcement and concrete substrate is of critical importance for the effectiveness of this strengthening technology. As a result, the design of reinforced concrete (RC) members strengthened with FRP composites is to account for, among other failure modes, the debonding of the laminate from the substrate. Although analytical and experimental research conducted for over two decades has led to archival publications and guides, no standard test methodology is yet available for shear bond strength evaluation after aggressive environmental conditioning. This paper aims at studying the durability of the bond strength between carbon FRP (CFRP) laminate and concrete substrate. The set-up consists of a small, plain concrete beam reinforced with an externally-bonded CFRP laminate that is tested under three-point bending. The force that the CFRP laminate can bear before detaching is easily calculated and the effect of accelerated conditioning is thus evaluated. Different environments and times of exposure are considered including 100% relative humidity, saltwater, alkali solution and dry heat. Statistical analysis are carried out to obtain statistical evidence on the effect of both the conditioning environment and the time of exposure on shear bond strength. The test methodology used in this work has the attributes of an effective standard.