Evaluation of external FRP-concrete bond in repaired concrete bridge girders and columns

Abstract Fiber reinforced polymer (FRP) is increasingly used to strengthen damaged or structurally unsafe concrete bridges. The FRP wrapping on eight concrete bridges was evaluated with ASTM pull-off testing to assess the condition of the bonding. A majority of samples failed in the concrete substrate. However, large variations in failure modes and pull-off strengths were observed, possibly due to environmental degradation or improper application. A majority of samples failed in the ASTM Mode G in concrete. Average bond strength from columns samples was 20 % lower than that from girders, due to the difficulty of pull-off testing on round column surfaces.