Chloride-induced macrocell corrosion of steel in concrete—theoretical background and practical consequences

Abstract

Due to the large extent of corrosion problems in reinforced concrete structures all over the world the durability of concrete structures exposed to aggressive environments has become a problem of major importance. New results from research on chloride-induced corrosion of steel in concrete show that the corrosion mechanisms are quite complex. Normally locally separated anodically and cathodically acting steel surface areas are formed on the steel surface. As the cathodically acting steel surface areas are not visible, the corrosion mechanisms can only be investigated indirectly using new electrochemical testing methods. In this paper the theoretical background of chloride-induced macrocell corrosion of steel in concrete is explained and additionally examples for macrocells in practice are given. In particular, the formation of macrocells in the area of cracks in concrete and the problem of macrocell corrosion after local repair measures and the consequences on the design of durable new concrete structures and repair measures are discussed.