Modelling of shear strength at the interface between concrete and microconcrete for jacketing of structural members

सार

Concrete jacketing is a retrofit strategy for strengthening of building members. The present study investigated the shear strength and slip behaviour of interface between old (low strength base concrete) and new concrete (high strength micro-concrete), as relevant to a jacketed member. Slant shear, double shear and uniaxial compression tests of plain concrete prism specimens were carried out under monotonic compression. For each type of test, monotonic compression was applied using a displacement controlled testing machine. The slip at the interface of a specimen was measured using digital image correlation method. Next, a failure criterion for shear strength of the interface between old and new concrete was developed. It is based on applying the two dimensional linear form of the Mohr–Coulomb criterion to the state of stress for the old concrete at the interface. The failure criterion is corroborated using the Mohr’s circles of stresses at failure in the old concrete near the interfaces for the slant shear tests. This can be used to predict any debonding of the jacket concrete for a retrofitted short-span shear dominated member in a building.