Interaction between loading, corrosion, and serviceability of reinforced concrete

The present research studies the mutual effects between mechanical loading and corrosion of reinforcing steel, as well as their combined effect on serviceability (flexural deflection and residual loading capacity) of reinforced concrete beams. Beam specimens 10 x 15 x 117 cm in size were subjected to four-point bending at various loading levels (0-75% of the ultimate load) with different loading histories (previous loading and sustained loading). NaCl solution ponding was employed to accelerate the corrosion process. Half-cell potential and galvanized current measurements were taken to monitor time for corrosion initiation. After corrosion initiated, an external current was applied to some of the specimens to expedite corrosion propagation. Beam deflections were recorded throughout all of the tests. Residual flexural loading capacity of the beams was evaluated at the end of the experiment. The results indicate that loading history and loading level have significant effects on both corrosion initiation and the rate of corrosion propagation. The failure mode of the reinforced concrete beams appeared to shift from a shear failure of concrete to bond splitting as the degree of corrosion increased. The results suggest that for a rational service-life prediction of reinforced concrete structures, the influence of the service load on the structure performance should be considered in combination with environmental conditions and material proportions.