Durability of FRP to Concrete Bonded Interface Under Accelerated Ageing

Externally bonded carbon Fiber Reinforced Polymers (FRPs) are now commonly used for the strengthening and repair of Reinforced Concrete structures. However, if the effectiveness of this technique has been widely demonstrated, the durability of the adhesive bond at the concrete/composite interface is still a matter of investigation and remains a critical issue to be addressed in order to assess the long-term performance of FRP strengthening methods. The proposed paper aims at presenting the first results of an ongoing investigation on the time evolution of the concrete/composite adhesive bond strength. Such an evolution was studied by performing double lap shear tests, while changes in the mechanical properties of the polymer adhesive were investigated by means of tensile tests. Preliminary results show that shear tests are able to reveal evolutions of both the bond strength and the failure mode of concrete/composite assemblies subjected to various accelerated ageing conditions. The weakest part of the assembly, initially assigned to the concrete substrate (cohesive failure in concrete), is progressively transferred to the polymer joint (adhesive failure at the bonded interface).