Experimental research into the relation between the peeling angle and the debonding of CFRP laminates bonded to concrete

CFRP is a relatively new, innovative strengthening material to strengthen reinforced concrete structures. Main issue, when strengthening a concrete structure is the debonding of CFRP. Although a lot of research has been carried out into the debonding behavior, still some questions remain open. In literature, several debonding mechanisms are distinguished. One of the debonding mechanisms is "peeling-off caused at shear cracks". In this mechanism, it is expected that the debonding is initiated by exceeding the tensile strength of concrete perpendicular to the CFRP. This tensile stress is caused by the difference in horizontal as well as in vertical displacement between either sides of a shear crack. This difference in horizontal and vertical displacement will induce a peeling angle, under which the CFRP is pulled off from the concrete surface. In this report, the results of an experimental research into the relation between the peeling angle and the debonding load of CFRP laminates externally bonded to concrete are given. The tests are carried out at the Pieter van Musschenbroek laboratory of Eindhoven University of Technology. With the results of the experiments, some remarks on the debonding mechanism "debonding caused at shear cracks" will be made.