Study of Influence of Corrosion and Cracking on Bond Behavior of Reinforced Concrete Member

Abstract

Reinforced concrete, as composite material has occupied special place in the modern construction of different type of structure. Reinforced concrete is inherently durable and near maintenance free construction material. Service life of reinforced concrete structure can be significantly reduced when the corrosion of reinforcing steel is initiated; the product of corrosion expands and occupies greater volume than original volume of steel, eventually causes cracking of concrete. The composite action of concrete and steel in reinforced concrete structures is provided by bond strength. The required bond strength is achieved by providing sufficient development length. Non-provision of adequate development lengths often results in failures, especially in cantilever supports, lap splices and beam - column joints. In this study, pullout test have been carried out to study the influence of reinforcing bar corrosion and cracking on bond strength of reinforced concrete member. Bond behavior is studied at different level of corrosion of reinforcement bar. These stages of corrosion have been achieved by impressing direct current for increasing period on the reinforcing bar embedded in the pullout specimen placed in 5% NaCl solution, the current is so arranged that the reinforcing bar serves as the anode, while steel mesh serves as cathode. The bond strength increases with corrosion up to certain limit. However, with progressive increase in corrosion, the bond strength decreases rapidly for pullout test.