Effects of stirrup corrosion on bond–slip performance of reinforcing steel in concrete: An experimental study

Abstract

Stirrups are relatively vulnerable to marine environment corrosion, as their protective layer is thinner than that of rebar. Stirrup confinement would increase bond performance of reinforcing steel in concrete; however, little is known regarding the effects of stirrup corrosion. This paper studies the effects of stirrup corrosion on bond performance between rebar and concrete. Tests were carried out to evaluate the degradation of bond performance of reinforcing steel in concrete for different stirrup corrosion levels. A series of 20 specimens with various stirrup corrosion levels were designed and manufactured. Each specimen was cast as a 200mm concrete cube, and a steel rebar was centrally embedded with two stirrups around it. The stirrups were corroded using an electrochemical accelerated corrosion technique with the rebar intact. The corrosion crack opening width and length were recorded after the corrosion process. Then monolithic pull-out loading tests were carried out on the specimens. Constant and varied cyclic slip loading tests were also carried out to further explore the cyclic bond performance of reinforcing steel in concrete. The effects of stirrup corrosion on crack opening, maximum bond stress, effective bond stiffness, unloading stiffness, energy dissipation, frictional bond resistance and residual bond stress were discussed in detail. It was found that stirrup corrosion has non-negligible effects on bond performance of reinforcing bar in concrete. The coupled effects of corrosion and cyclic loading damage on bond performance of reinforcing steel in concrete were observed from the cyclic loading tests.