The electrochemical behaviour of steel rebars in concrete: an Electrochemical Impedance Spectroscopy study of the effect of temperature

• pH of concrete pore solution decreases as temperature increases.
• Concrete's conductivity follows Arrhenius type dependence of the temperature.
• The corrosion rate of the studied materials, studied through Rp, follows the Eyring law.
• Relationship Rp vs Re can only be established for particular combinations of rebar/concrete microstructure.

The effect of temperature on the electrochemical behaviour of reinforced mortar samples contaminated with chlorides was investigated using EIS. The results show an exponential dependence of the mortar cover resistivity with the temperature. This dependency was interpreted as being due to electrostatic interaction between moving ions and charged pore walls, at the gel level structure.The corrosion rate showed a complex dependency with temperature. The Eyring equation explained the behaviour, with distinct reaction paths above and below about 30 0C, the temperature at which the electrolyte reached a pH of 12. In the presence of chlorides, the pH was lower for a given temperature.

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