Bond Between FRP (Fiber Reinforced Polymer) Sheets and Concrete: Experimental and Theoretical Study

The use of Fiber Reinforced Polymers for strengthening and repair of reinforced concrete structures seems to be an attractive solution in the field of civil engineering. FRP laminas or sheets may be utilized in order to enhance flexural and/or shear capacities of damaged reinforced concrete beams in terms of stiffness and strength while wrapping reinforced concrete columns appears a promising solution for improving theirs strength and ductility. However, experimental and theoretical researches are always necessary and interesting because of techniques are still new and suitable models are needed for a reliable design. In particular, bond between concrete and FRP is still an open problem because of the lack of a standard tests, the great variability of parameters involved and, therefore, the difficulty for assessing a bond law of general validity. The aims of this paper is to investigate the bond between FRP sheets and concrete varying the type of test and the type of fibers. In particular the influence of the stiffness of the reinforcement has been evaluated considering carbon and glass fibers, while the influence of test procedure has been studied performing beam test and direct shear strip test. On the basis of experimental results and considering the bond model available in the literature a theoretical analysis has been also carried out. The obtained theoretical and experimental results are compared and discussed