4. Steel corrosion-inducing phenomena in concrete: carbonation and chloride penetration

Reinforcement corrosion in reinforced concrete structures is induced by two distinct phenomena:

• carbonation of concrete, by penetration of a CO ₂ front from the surface to the core of the concrete ;

• chloride ion penetration for structures in marine environments (submerged, in tidal zones, subject to splashing or spray), or exposed to de-icing salts in environments at risk of freezing (direct contact, splashing, run-off, etc.).