Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. I: Application of Electrochemical Techniques

Koleva, D.A.; De Wit, J.H.W.; Van Breugel, K.; Lodhi, Z.F.; Van Westing, E.

doi:doi:10.1149/1.2436609

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. I: Application of Electrochemical Techniques

Title

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. I: Application of Electrochemical Techniques

Author

Koleva, D.A.
De Wit, J.H.W.
Van Breugel, K.
Lodhi, Z.F.
Van Westing, E.

Faculty

Civil Engineering and Geosciences

Department

Design and Construction

Date

2007-02-27

Abstract

The electrochemical behavior of steel reinforcement in conditions of corrosion and cathodic protection was studied, using electrochemical impedance spectroscopy (EIS) and compared to reference (noncorroding) conditions. Polarization resistance (PR) method and potentiodynamic polarization (PDP) were employed as well, in addition to ac 2 pin electrical resistance monitoring, thus deriving a comparison of the involved parameters, mainly polarization resistance and bulk electrical properties, obtained by all methods. It was found out that EIS is readily applicable for evaluating electrochemical behavior of the steel surface not only for corroding or passive state, but also in conditions of cathodic protection, although the interpretation of derived parameters is not straightforward and is related to the properties of the product layers, formed on the steel surface in the different conditions. For verification of the latter dependence, EIS, PDP, and PR measurements were performed additionally in cement extract solution, using steel samples from the previously embedded rebars in all technical conditions. The bulk matrix properties in passive, corroding, or under-protection conditions can be well defined by EIS. The evaluation of the electrochemical behavior of the steel surface, in terms of deriving polarization resistance, should take into account the crystallinity, morphology, and composition of the surface layers, which were investigated by scanning electron microscopy and energy dispersive X-ray analysis.

Subject

steel
reinforced concrete
corrosion protection
electrochemical impedance spectroscopy
electrical resistivity
crystal structure
surface morphology
surface composition
scanning electron microscopy
X-ray chemical analysis