CORROSION OF STEEL BARS IN CRACKED CONCRETE UNDER MARINE ENVIRONMENT

This paper deals with the macrocell and microcell corrosion of steel bars in cracked concrete exposed to a marine environment. For this, short-term accelerated laboratory and long-term exposure tests were carried out. Test items include electrochemical and physical evaluations of corrosion, chloride ion content in concrete, and oxygen permeability through concrete. Analyses by scanning electron microscopy and electron probe microanalyzer were also carried out to confirm the deposit in the healed cracks. For an unhealed crack, the portion of the steel bar located at the root of the crack acts as an anode and other portions as a cathode. Also, microcell corrosion at the cracked region is higher than the uncracked region. Macrocell corrosion process and the degree of macro and microcell corrosion are significantly influenced by the water/cement. In a natural marine environment, narrower cracks heal due to the deposition of ettringite, calcite, and brucite in the crack. This reduces the corrosion rate significantly at the cracked region.