Diffusion of Dissolved Oxygen through Concrete

Concrete normally provides to embedded steel a high degree of protection against corrosion, and this is because the high alkalinity in concrete forms a thin protective film of γ - Fe2O3 on the steel surface. Under certain circumstances, however, this protective film can be disrupted either by a lowering of pH of the water phase in concrete (e.g. by carbonation) or by a penetration of aggressive ions (e.g. chloride ions) to the steel surface.