More than 30 years have passed since the steel plate bonding technique was applied for the first time to reinforced concrete (RC) slabs of road bridges in Japan as a strengthening measure against fatigue damage. Debonding of the steel plates as well as damage in concrete are often found as a dull sound during hammer tests. Efforts are being made for more frequent inspections; however, visual observation has a limitation in detecting damage in the concrete of the repaired slabs which are covered with steel plates at the bottom. Although the presence and extent of debonding can be roughly known from the change in sound during hammer tests, there are no decisive methods to detect or evaluate the internal damage of the concrete. The purpose of this study is to establish a method to evaluate damage in concrete of steel plate-bonded RC slabs on road bridges in service, with the focus placed on the temporary set anchors in the repaired slabs which had been used to hold the steel plates until settlement of adhesive agent for secure bonding. The proposed technique utilizes the anchor bolts as ultrasonic probes.

In this research, the application of repair methods of water leakage cracks using self-healing technologies for subway tunnels is presented. In order to apply crack self-healing water stop agents and quick setting agents in subway tunnels, laboratory and field tests were performed based on various previous researches. Especially, this study focused on development of crack repair materials and their new repair methods. Therefore, various repair materials were examined for new repair materials with self-healing capability applied to crack sealing method and to patching repair method. The results show that the proposed water leak repair methods using water stop agent, quick setting agent and patching materials using self-healing ingredient were effective under the subway tunnel conditions. It is preferable in water leak repair to add self-healing components to sealers and water stop agents.