Reinforcing steel that's visible on the concrete surface may occur in any type of reinforced-concrete structure. The exposed reinforcing steel may result from deterioration within the concrete or from errors during construction. When concrete deterioration exposes rebar, the problem usually is the result of steel corrosion, freeze-thaw damage, or both.
The keys to preventing corrosion are providing adequate concrete cover depth and preventing or slowing chloride entry by using sealers or membranes or by reducing concrete permeability. Another option is changing the corrosion threshold by using a corrosion-inhibiting admixture or epoxy-coated, galvanized, or stainless reinforcing steel.