Effect of Non-homogeneous Nitrite Ions on the Macrocell Corrosion Behavior of Reinforcing Steel Embedded in Concrete Structures

Based on macrocell corrosion theory, cathodic steel bar and anodic steel bar were casted in two separated cement mortar blocks in which nitrite solution with different concentrations were filled to simulate the penetration process of nitrite ions, then cathodic steel bar and anodic steel bar were connected or disconnected by lead wire to simulate the macrocell corrosion or microcell corrosion. The influence of non-homogeneous nitrite ions on the macrocell corrosion behavior of reinforcing steel was investigated by comparing the magnitude of macrocell current flowing between anodic and cathodic steels. The results indicated that the presence of nitrite only on the surface of anodic steel could increase the macrocell polarization resistance of anodic steel, reduce the macrocell potential difference, decrease the macrocell corrosion currrent and therefore effectively inhibit the macrocell corrosion. The presence of nitrite only on the surface of cathodic steel could enhance the macrocell potential difference, increase the macrocell corrosion currrent and therefore have a risk to accelerate the macrocell corrosion.