Utilization of Ground Penetrating Radar (GPR) in the Non-destructive Assessment of FRP Laminate-Concrete Bond Strength
Repair and rehabilitation methods for civil infrastructure have become a topic of great interest to engineers, and fiber reinforced polymer (FRP) laminate is one of the most popular and practical solutions for strengthening and retrofitting of concrete structures. Several past studies indicated that significant increase in strength and stiffness can be achieved by using this technology. The quality of the FRP-concrete bond is critical in transferring stresses through the interface, and the in-situ evaluation of the bond strength is still a challenging issue.
To quantitatively evaluate the bond strength, non-destructive technique (NDT) using ground penetrating radar (GPR) was utilized on 32 laboratory concrete beams strengthened with carbon FRP (CFRP) laminates. Various parameters that may affect the bond strength, such as surface roughness, voids, epoxy type and thickness, and FRP type, were considered. The experiment was conducted with the objective of non-destructively detecting the parameters. The associated bond capacity of each sample was then found through a three-point bending test and also correlated through finite element modeling. Quantitative relationships between each of the parameters in the study and the associated bond strengths were then developed. The results of this study will be very useful in estimating the in-service bond conditions of applied FRP laminate, thereby estimating the expected strength contribution of the laminate in the overall flexural strength of structural members.
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