Corrosion of steel in concrete and its prevention in aggressive chloride-bearing environments

This keynote paper deals with the durability of reinforced concrete (RC) structures exposed to aggressive environments characterized by high concentration of chloride ions, namely marine environments or the use of de-icing salts. The mechanism of chloride-induced corrosion of steel in concrete is introduced and its influence on the service life of RC structures is analyzed. Factors affecting the time to corrosion initiation are described with regard to both concrete properties and environmental exposure conditions. Design approaches available for achieving durability targets associated to the design service life are analyzed, focusing on studies carried out by the Authors in recent years at the mCD Concrete durability lab of Politecnico di Milano, which were aimed at improving the protection provided to the steel bars by the concrete cover, investigating the advantages of using corrosion resistant stainless steel bars and developing the electrochemical technique of cathodic prevention.