Bond properties of a newly developed composite rebar

Load transfer along the surface of unidirectional composites such as GFRP rebar is problematic. The properties of the rebar itself and the surrounding concrete are the critical factors. The newly developed composite rebar ComBAR has a volume content of 75% ECR-glassfibres and is based on a vinyl-ester hybrid resin. The surface geometry of the trapezoidal ribs has been optimised for a secure bond behaviour. A testing program on the relevant properties is presented. The ductility of the bond and the dependence of the bond strength on the concrete strength are shown in RILEM pullout tests. In eccentric pullout tests the low splitting forces are shown. Reinforced beams are tested to show the behaviour of standard development lengths. A detailed comparison of the bond behaviour with that of reinforcing steel is presented.