Experimental comparison of corrosion unevenness and expansive cracking between accelerated corrosion methods used in laboratory research

Eight reinforced concrete (RC) slabs were prepared and corroded using different accelerated corrosion setups including full-immersion, half-immersion, and wet-dry cycling, aiming to investigate their differences in terms of non-uniform corrosion distribution and expansive crack opening. Embedded steel bars were retrieved and cleaned before scanning into 3D models using a laser instrument to facilitate precise geometric measurement. Non-uniform corrosion is quantitatively characterized by a parameter Rn, whose asymptotic distributions belong to the domain of attraction of general extreme value (GEV) distribution. The results show that full-immersion method is less promising, because it generated the slightest non-uniform corrosion and expansive crack opening. The half-immersion method could be used in the research focusing merely on corroded steel bars as it led to serious non-uniform corrosion but less severe expansive cracking. Wet-dry cycling seems to be the best, whereas the impressed current density is recommended to be kept below 50 μA/cm2.