Metallic corrosion can cause substantial damage at various levels and in almost all types of infrastructure. For metallic corrosion to occur, a certain external environment and the presence of corrodents are the prerequisites. Stray current-induced corrosion, however, is a rather underestimated issue in the field of corrosion and civil engineering. Stray current arising from power sources and then circulating in metal structures may initiate corrosion or even accelerate existing corrosion processes. The most frequent sources of stray current are light rail transits and subways, which are also main traffic tools with continuously accelerating urbanization all over the world. Stray currents from these systems may easily flow into nearby metallic structures, making stray current-induced corrosion the most severe form of damage of buried structures, such as tunnels, pipelines, and various underground reinforced concrete structures. The objective of this paper is to critically review stray current-induced steel corrosion in infrastructure with regard to sources of stray current and the characteristics and mechanism of stray current corrosion in view of electrochemical aspects. The methods and techniques for the evaluation, monitoring, and control of stray current-induced corrosion for steel and reinforced concrete structures are also presented and discussed.

Different concrete structures (viaducts, bridges, or tunnels) in the neighborhoods of railways may be subject to the stray current leaking from the rails. In these cases, the reinforcing rebars embedded in concrete act as conductors, “pick up” the stray current, and can corrode. For simulating the stray current-induced corrosion of metals, most researchers just supplied anodic polarization on samples. However, stray current induces both cathodic polarization and anodic polarization. This work experimentally justifies the different effects of stray current and anodic polarization on reinforcing steel embedded in mortar. A comparison between stray current and anodic polarization effects on the corrosion behavior of embedded steel is performed for both fresh (24 hour-cured) and hardened matrix (28 day-cured) in chloride-free (Cl-free) and chloride-containing (Cl-containing) environments. It is found that in all studied conditions, anodic polarization leads to a significantly different electrochemical performance of the steel rebar compared to the stray current. Hence, anodic polarization cannot reflect all the effects of stray current, and therefore, it has limited significance for simulating stray current. It is also clarified that the curing regimes and starting time of the stray current play significant roles in the formation of a corrosion product layer on the steel surface.