Corrosion Behavior of Reinforcing Steel in Concrete Systems

Reinforcing steel embedded within concrete relies on a high‐pH pore solution to form a protective passive film that inhibits corrosion. This film, comprising iron oxides and hydroxides, remains stable under alkaline conditions but can be compromised by ingress of aggressive agents such as chlorides, carbon dioxide and stray electrical currents. Chloride ions, often originating from de‐icing salts or marine environments, disrupt the passive layer by promoting localised breakdown and pitting corrosion. Carbonation of the concrete reduces pore‐solution alkalinity, leading to uniform depassivation and general corrosion along the steel surface. Additional factors—such as microstructural defects at the steel–concrete interface, moisture transport, and the presence of redox‐active species—further influence corrosion initiation and propagation. Contemporary research has focused on enhancing durability through tailored cementitious matrices, novel binder chemistries, and corrosion‐resistant reinforcements, as well as the deployment of electrochemical monitoring techniques. Advances in nanoscale characterisation and modelling have elucidated the mechanisms of passive‐film growth and breakdown, enabling more accurate service‐life predictions and maintenance strategies. The global importance of reinforced concrete infrastructure, from coastal bridges to water treatment facilities, underscores the need for integrated approaches that combine materials innovation, structural design and real‐time diagnostics to mitigate corrosion and extend asset longevity.

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Corrosion Behavior of Reinforcing Steel in Concrete Systems publication trend

The graph below shows the total number of articles in corrosion behavior of reinforcing steel in concrete systems across all publications each year (not limited to Nature Index journals).

Technical terms

Passivation: The formation of a thin, adherent oxide layer on steel that inhibits further electrochemical attack.

Depassivation: The breakdown or removal of the passive film, exposing bare metal to corrosion.

Passive film: A protective oxide/hydroxide layer that forms on steel surfaces in high‐pH environments.

Electrochemical impedance spectroscopy (EIS): A technique that measures the impedance of a steel–concrete system over a range of frequencies to characterise corrosion processes.

Chloride‐induced corrosion: Localised corrosion triggered by chloride ions penetrating the concrete and destabilising the passive film.

References

1. The steel–concrete interface. Materials and Structures (2017).
2. Investigation of chloride-induced depassivation of iron in alkaline media by reactive force field molecular dynamics. npj Materials Degradation (2019).
3. The Passive Film Growth Mechanism of New Corrosion-Resistant Steel Rebar in Simulated Concrete Pore Solution: Nanometer Structure and Electrochemical Study. Materials (2017).
4. Effect of Silica Fume and Fly Ash Admixtures on the Corrosion Behavior of AISI 304 Embedded in Concrete Exposed in 3.5% NaCl Solution. Materials (2019).
5. EIS Investigation of the Corrosion Behavior of Steel Bars Embedded into Modified Concretes with Eggshell Contents. Metals (2022).
6. Effect of stray current coupled with chloride concentration and temperature on the corrosion resistance of a steel passivation film. Electrochemistry Communications (2020).
7. Evaluation of the influence of the pH of concrete pore solution on the corrosion resistance of steel reinforcement. Journal of Building Pathology and Rehabilitation (2016).
8. The Improvement of Durability of Reinforced Concretes for Sustainable Structures: A Review on Different Approaches. Materials (2022).