A review of the repair measures for reinforced concrete affected by chloride ion corrosion

Abstract

Chloride ion corrosion significantly impacts concrete structures and will lead to the loss of structural load-bearing capacity and service life. This article starts with the corrosion mechanism of chloride on reinforced concrete and reviews and researches the repair measures of reinforced concrete affected by chloride ion corrosion. Based on the mechanism of action and operating characteristics, this article divides repair measures into direct repair and electrochemical repair; according to the different degrees of structural damage, the corresponding direct repair measures are divided into crack repair and structural repair. Repair methods using anti-corrosion materials have additional advantages, such as flexible sealing, epoxy resin filling, etc. It should be noted that all the direct repair methods mentioned above have considerable applicability in general construction projects. The structural repair focuses on the additional reinforcement method and summarizes the additional reinforcement process for reinforced concrete damaged by corrosion. Ignoring chlorine removal and sacrificial anode protection measures, this process is also considered a general procedure for construction engineering. For repair materials, polymer cement concrete exhibits excellent resistance to chloride salt erosion, but is easily affected by temperature changes. Fiber-reinforced concrete has strong mechanical and corrosion resistance. Among which textile-reinforced concrete (TRC) is best, and the strength benefits are also quite prominent. Ultra-high-performance concrete (UHPC) is extremely resistant to corrosion and has other high-strength benefits, making it an ideal repair material for key parts of structures such as bridges and tunnels. For electrochemical extraction (ECE), titanium platinum is the optimal anode material and lithium-based electrolyte is considered the optimal electrolyte, with a recommended current density of 0.5–1.0A/m². Bidirectional electromigration (BIEM) can introduce corrosion inhibitors on the surfaces of concrete and steel bars while extracting chloride salts. Triethylenetetramine has the best comprehensive repair effect, but the 28-day repair efficiency is relatively low. Electrochemical deposition treatment (EDT) can repair small cracks, and the repair effect of MgSO₄ in conventional electrolytes is the best, with the highest economic benefits after 28 days. Pulse current can greatly improve repair efficiency, and the optimal pulse power is T_on/T_off = 0.8 ms/0.8 ms. However, for wide cracks, a combination of direct repair and electrochemical repair can achieve the best results. This article can serve as a guide for repairing reinforced concrete in an environment corroded by chloride ions.