Evaluation on Effect of Voids around Rebar on Corrosion Process regarding Rebar Embedded in Mortar and Crack Propagation using X-ray Tomography

The maintenance of concrete structures is challenging owing to the corrosion of reinforcing steel bars. The expanding pressure caused by corrosion leads to corrosion-induced cracking. Several studies have investigated the relationship between surface cracks and the mass loss of steel bars to establish efficient techniques for predicting mass loss in steel based on cracks. However, the effects of voids around steel bars on the cracking and corrosion of steel bars remain underexplored. This study evaluates these effects using X-ray imaging. Mortar specimens reinforced with an axial steel bar were prepared; the steel bar was corroded using the impressed current technique. X-ray imaging was used to visualize the corrosion products filled in the voids around the steel bar. The propagation of cracks eventually diminished because of the voids in the early phase of corrosion. In addition, as the cracks progressed due to corrosion, the influence of voids around the steel bar became less pronounced.