2025 Volume 4 Issue 1 Pages 38-47
Urban tunnels located near seaside areas have been suffering from salt-induced deterioration due to leakage of seawater, Therefore, maintenance and management of these tunnels are difficult. To address this problem, we developed a new shotcrete repair method that combines fiber-reinforced polymer cement mortar with calcium aluminate hardening agents and salt-fixing agents, and then adds liquid plasticizer just before the nozzle at the end of the spraying equipment. We then used an actual structure to confirm the effectiveness of this method in preventing re-deterioration due to macroscopic cell corrosion around the repaired area after construction by measuring the natural potential. As a result, the corrosion current was limited even 24 months after the repair, and there was no sign of re-deterioration. Subsequently, the repair method was applied to actual structures on a railway line in operation. As a result, no initial crack nor other abnormalities occurred at the repaired area, sufficient adhesion strength was confirmed,, and the construction cost was reduced by approximately 20%.
