How does cathodic protection prevent corrosion of steel structures?

Cathodic protection prevents the corrosion of steel structures by converting the entire structure into a cathode, thereby suppressing the oxidation process that causes metal to lose electrons and degrade.1

This is achieved through two primary methods:

• Sacrificial Anodes: A more active metal, such as zinc or magnesium, is attached to the steel structure. Because these metals are more reactive, they corrode preferentially, effectively "sacrificing" themselves to protect the steel.21
• Impressed Current: An external power source is used to supply a continuous flow of electrons to the structure. By providing these electrons, the method prevents the steel from undergoing the anodic reaction that would otherwise lead to the formation of rust.1

Unlike simple barrier coatings, which can be compromised by physical damage, cathodic protection provides active electrochemical defense for the underlying metal.13