Creep behavior of adhesives used for external FRP strengthening of RC structures

It is technologically possible to strengthen steel-reinforced concrete structures with externally bonded carbon–epoxy composites. The durability and performance of those reinforcements directly depend on the rheological behavior of the concrete–composite interface. We propose a methodology to evaluate the permissible shear stress of the interface, based on thermo-stimulated tensile shear tests performed on the interface, and taking into account the effects of time and temperature. Four polymers used for bonding were tested and a value for the permissible shear stress is proposed for each strengthening system.