Evaluation of corrosion-induced crack and rebar corrosion by ultrasonic testing

Abstract Recently, the maintenance of concrete structures has become important for the sustainability of infrastructure. Steel-bar (rebar) corrosion is one of typical deteriorations to reduce the service life of concrete structures. Corrosion products of rebar cause cracking in concrete. When these cracks reach to the concrete surface, the damage of rebar corrosion is readily recognized by visual inspection. In this case, however the damage is referred to as the acceleration stage. In order to evaluate the performance of concrete members and structures, it is important to evaluate the corrosion of rebar as early as possible. Thus, the corrosion of rebar is often detected directly to remove cover concrete. In this concern, nondestructive evaluation is important to detect the corrosion and corrosion-induced cracking inside concrete at the dormant and the initiation stage prior to the acceleration stage. In the acceleration stage, it is important to detect the corrosion precisely and to evaluate the cracking of concrete. In order to detect rebar corrosion at early stage, ultrasonic testing is applied. The damage of concrete and cracking under an electrolytic corrosion test is estimated.