Outdoor exposure tests were conducted on reinforced concrete samples with cracks less than 0.1 mm in width. The corrosion behavior of the reinforcing bars was evaluated by measuring the potential difference between the two bars within each specimen and by weighing the specimens. A temporary increase and decrease in the potential difference of the reinforcing bars was observed during the outdoor exposure tests. Upon dismantling the samples, traces of reinforcing bar corrosion were confirmed. Furthermore, since the increase in potential differences progressed during periods of heavy rainfall, it is inferred that this resulted from the carbonation of the environment due to massive water ingress into the cracks, leading to de-passivation of the reinforcing bar. Conversely, the decrease in potential difference is thought to result from the re-passivation of the reinforcing bar due to the creation of an alkaline environment caused by the leaching of unhydrated cementitious components into the water retained within the cracks. These results indicate that in reinforced concrete with micro-cracks of 0.1 mm or less in width, the integrity of the reinforced concrete may be maintained through self-healing.
Takeuchi et al. (Tue,) studied this question.