Definition - What does Macrocell Corrosion mean?
Macrocell corrosion is a type of corrosion that occurs in the steel bars (reinforcement steel or rebars) used in those building structures that are completely covered by concrete. The corrosion occurs because of an oxidation process in which the passive film on the steel rebars break down due to the presence of chloride ions or carbon oxide around the reinforced steel.
Corrosionpedia explains Macrocell Corrosion
Macrocell corrosion is basically a macrocell circuit (i.e., corrosion circuit) that occurs in steel objects enclosed in soil or a solidified concrete structure where an anode and a cathode are separated from each other. Macrocell corrosion is different from microcell corrosion, which occurs in steel structures where the anode and cathode are located next to each other.
Macrocell corrosion occurs due to the presence of impurities, environmental conditions and other factors.