Bond-slip behaviour of corroded reinforcement and ultra-high toughness cementitious composite in flexural members

Abstract Bonding between ultra-high toughness cementitious composite (UHTCC) and corroded reinforcement has a great effect on the mechanical behaviour of reinforced UHTCC members subjected to chloride attack and of corroded structural members repaired with UHTCC. This paper presents an experimental study on bonding between UHTCC and post- and pre-corroded rebar using bending tests. The test parameters included corrosion ratio and bond length. Failure and cracking pattern, bond-slip curves, bond strength, and bond toughness were compared. The bond strength decreased with increasing bond length, and increased initially and then decreased with increasing corrosion ratio. The critical corrosion ratio, at which the bond strength became lower than the initial strength, was approximately 12–13.5% for post-corrosion specimens and 13.5–18% for pre-corrosion specimens. The residual bond strength of pre-corrosion specimens was superior to that of post-corrosion specimens. Rebar corrosion obtained at these corrosion levels had hardly any negative effect on the bond toughness index.