Assessment of the mechanical behaviour of reinforcement bars with localised pitting corrosion by Digital Image Correlation
Journal article, 2020

Corrosion of reinforcement in concrete impairs the mechanical behaviour of rebars by decreasing their strength and deformation capacity. In this study, uniaxial tensile tests were carried out on 61 rebars taken from 22 pre- and un- cracked reinforced concrete beams subjected to drying and wetting cycles in chloride solution for over three years. A 3D-scanning technique was used to characterise the maximum local corrosion level, μmax, and different pit shape parameters. Digital Image Correlation (DIC) was used to capture the displacement field of the test bars; the engineering strain was measured through the virtual extensometers created in the DIC post-processing software. The proof and ultimate forces showed linear decreasing trends of μmax, while the proof and ultimate strengths (based on the minimum residual cross-sectional area) were not obviously affected by corrosion. The ultimate strain of corroded bars depended on the gauge length due to strain localisation in the pit. Thus, it was emphasised that the ultimate strain may be overestimated if measured based on a short gauge across the pit. It was also observed that when μmax exceeded a critical local corrosion level (μcrit depending on the ratio between the yield and ultimate strengths of the steel), the region outside the pit did not develop yielding. A lower bound of ultimate strain was further derived as a function of the mechanical parameters of uncorroded steel and maximum local corrosion level. This provided a good comparison with the experimental results. Ultimately, a hypothesis for time-dependent assessment of strain capacity is proposed, considering the evolution of corrosion morphology over time.


Pitting corrosion

Mechanical properties

Strain measurement

Digital Image Correlation


Teresa E Chen

Chalmers, Architecture and Civil Engineering, Structural Engineering

Carlos Gil Berrocal

Thomas Concrete Group

Chalmers, Architecture and Civil Engineering, Structural Engineering

Ignasi Fernandez

Chalmers, Architecture and Civil Engineering, Structural Engineering

Ingemar Löfgren

Chalmers, Architecture and Civil Engineering, Structural Engineering

Thomas Concrete Group

Karin Lundgren

Chalmers, Architecture and Civil Engineering, Structural Engineering

Engineering Structures

0141-0296 (ISSN) 1873-7323 (eISSN)

Vol. 219 110936

Hybrid reinforcement solutions in chloride environment: durability, safety and life cycle costs

Swedish Transport Administration (TRV 2018/36506), 2018-06-01 -- 2020-08-30.

Cementa (17243), 2018-06-01 -- 2020-08-30.

Development Fund of the Swedish Construction Industry (SBUF) (13683), 2019-10-01 -- 2020-08-31.

Subject Categories

Infrastructure Engineering

Metallurgy and Metallic Materials

Corrosion Engineering



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