X線CTを用いたモルタルに埋め込んだ鉄筋の腐食による内部ひび割れおよび欠陥がひび割れ進展に及ぼす影響の評価

抄録

Corrosion of reinforcing steel bars poses a serious challenge in concrete structure maintenance. This corrosion causes not only surface cracks but also internal cracks in the concrete owing to the expanding pressure caused by corrosion. Several studies have focused on the relationship between surface cracks and the mass loss of steel bars, seeking to establish practical inspection methods that can predict the mass loss of steel on the basis of surface cracks. However, the effects of internal cracks, or the fragile portions previously formed in concrete, on the surface cracks and corrosion of steel bars have not been sufficiently investigated. This study evaluated these effects by using X-ray technology. Mortar specimens with both axial and transverse steel bars were prepared, and one of the steel bars were corroded using the impressed current technique. X-ray imaging was used to visualize the internal cracks in the specimens. Consequently, it was revealed that the propagation of surface cracks may be diminished because of internal cracks and fragile portions in the concrete.