Corrosion inhibitors do two things.
First, they extend the time before corrosion begins, and second, they tend to reduce the amount of corrosion that takes place. They can be either anodic, cathodic, or a combination. Some work to create a protective barrier that stabilizes the layer of rust surrounding the steel, others provide a thin protective coating that prevents chlorides from reacting with the steel. Yet others provide inhibitors that react with the iron to form a protective film or coating that either prevents chloride from reaching the steel, or reduces the corrosion of steel by acting as an oxygen barrier. Com 2000 Concretenetwork.