Influence of Internal Chloride and Cracking on the Corrosion Behavior of Steel in Mortar

Chloride-induced steel corrosion has been identified as the major reason for the durability deterioration of reinforced concrete structures in the marine environment. In this paper, the influence of internal chloride content and the cracking on corrosion behavior of carbon steel in mortar was experimentally investigated. First, the corrosion behavior of carbon steel embedded in an ordinary mortar containing different chloride content (ranging from 0 to 0.6% vs. binder mass) below the chloride threshold level was characterized by electrochemical impedance spectroscopy (EIS) and corrosion potential measurement. In terms of the cracking, corrosion behavior of carbon steel embedded in cracked mortar subjected to different exposure environments of air, water dry-wet cycles, and NaCl solution dry-wet cycles were reflected by corrosion potential measurement. The obtained results indicate that low chloride content does not influence the final passivation degree and polarization resistance of steel in mortar. However, when mortar is exposed to a humid environment, the activity of rebar is noticeably improved. Under the coupled action of cracking and dry-wet cycles, the corrosion rate of carbon steel in mortar sample increase with the increase of crack width. Once the cracked mortar is exposed to NaCl solution, even a tiny crack width increases the corrosion risk of Carbon steel.