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 ser viceability (flexural deflection and residual loading capacity) of reinforc ed concrete beams. Beam specimens 10 x 15 x 117 cm in size were subjected t o four-point bending at various loading levels (0 similar to 75% of the ult imate load) with different loading histories (previous loading and sustaine d loading). NaCl solution pending 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 ext ernal current was applied to some of the specimens to expedite corrosion pr opagation. Beam deflections were recorded throughout all of the tests. Resi dual flexural loading capacity of the beams was evaluated at the end of the experiment. The results indicate that loading history and loading level ha ve significant effects on both corrosion initiation and the rate of corrosi on propagation. The failure mode of the reinforced concrete beams appeared to shift from a shear failure of concrete to bond splitting as the degree o f 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.