Mechanism of Concrete Structure Failure Induced by the Corrosion Acceleration Test of Embedded Steel by the Anodic Polarization

An iron specimen embedded in a cement test block was anodically polarized to investigate corrosion and cracking by measuring compressive force with a load cell. The specimen exhibited two stages: unchanged force in Stage I and a linearly increasing compressive force in Stage II . In Stage I , local acidification from water decomposition dissolved the surrounding cement, creating a void that allowed Fe 2+ ions to dissolve, migrate, and precipitate as rust on the cement wall. In Stage II , the void was filled by redeposited iron‐rust‐containing cement, after which continued polarization promoted rust growth on the iron surface. The resulting volume expansion generated tensile force in the cement, leading to cracking. Raman and XRD analyses identified corrosion products, including Fe 3 O 4 , Fe 2 O 3 , α‐FeOOH, and γ‐FeOOH, although some phases may have formed via oxidation upon exposure to air.