The effects of corrosion on the performance of reinforced concrete beams

This report presents the results of a laboratory investigation into the effects of corrosion on the structural behaviour of reinforced concrete (RC beams. Twelve RC beams (156 x 176 x 1150 nun) were constructed, ten of which were corroded to various levels by impressed current while the remaining two were set aside as the control beams. Each beam was tested using non-destructive methods and then by four-point loading and the corresponding loads and deflections were recorded Following the mechanical testing, the tensile steel -was retrieved and cleaned in order to assess the mass loss. The results of this experiment clearly indicated a dramatic shift in the nature of the failure of corroded RC beams. Specifically, it was observed in the present study that as corrosion increased the failure mode of the beams shifted from predictable ductile flexure failures at mid-span, to more brittle failures near the support. Based on the data collected, several new corrosion-dependant empirical relationships were established to model the altered responses of RC beams (ie. stiffness, deflection ratio, ductility, and toughness). In addition to beam tests, a pullout study -was conducted in an effort to identify the relationship between the reduction of load-carrying capacity and the residual bond strength of the tensile steel Other behavioural changes examined are initial cracking load, flexural crack development and the evolution of the failure mode. It was found that the overall behaviour of the beam specimens tested conforms to that reported in the literature, with reductions in the ultimate capacity, deflection capacity and stiffness upon increasing corrosion. Also, the results of this experiment clearly indicated a dramatic shift in the nature of the failure of corroded RC beams. Specifically, it was observed that as corrosion increased, the failure mode of the beams shifted from predictable ductile flexure failures at mid-span, to more brittle failures near the support.