What mechanism does cathodic protection use to prevent corrosion in steel reinforcement?

Cathodic protection (CP) prevents corrosion in steel reinforcement by supplying an external electrical current to the steel, making it the cathode in an electrochemical cell. Corrosion occurs when steel acts as an anode, losing electrons and dissolving into the surrounding environment. By applying a direct current (DC) to the steel, CP forces the steel to become cathodic, which means it gains electrons instead of losing them. This prevents the oxidation reaction that causes corrosion. There are two main types of CP: impressed current cathodic protection (ICCP), which uses an external power source to drive the current, and sacrificial anode cathodic protection, which uses a more active metal (like zinc or magnesium) as an anode that corrodes instead of the steel. In both cases, the goal is to shift the electrochemical potential of the steel to a level where corrosion is thermodynamically impossible.