Durability Design of Concrete Structures

2Chloride Ingress and Induced Steel Corrosion

This chapter treats the deterioration of reinforced concrete by chloride ingress. The chlorides are present in seawater, groundwater, and deicing salts. The RC elements exposed to these sources can have the chlorides migrating from external environments into structural concrete. While the chloride ingress into concrete will not necessarily compromise the concrete properties, the chlorides can seriously destroy the electrochemical stability of the embedded reinforcement steel bars, inducing electrochemical corrosion. Actually, the deterioration of RC elements by chloride ingress has become one of the major concerns for durability of concrete structures. This chapter begins with some typical cases of RC elements and the structures affected by chloride ingress. The mechanisms are then introduced successively for chloride ingress and induced steel corrosion, together with an analysis on the main influential factors. Using the state‐of‐the‐art knowledge, the modeling of these processes is treated through mechanism‐based or empirical models. The basis for durability design against chloride‐induced corrosion is given at the end.

2.1 Phenomena and Observations

RC elements in concrete structures can be seriously affected by chlorides present in the environment. As concrete comes into contact with chlorides, the chloride ions can transport into the material via the pore space by several mechanisms. The electrochemical stability of the embedded ...