Electrochemical Techniques for Studying Corrosion of Reinforcing Steel: Limitations and Advantages

Abstract

This paper presents a comparison of the results obtained by different electrochemical techniques when applied to passive and active steel embedded in mortar or in simulated pore water solutions. The techniques investigated include polarization resistance by means of current or potential steps, potentiodynamic tests at different polarization rates, the application of potentiostatic and galvanostatic pulses, and electrochemical impedance spectroscopy (EIS). The differences between the corrosion current density (i corr ) values obtained using different techniques, or by applying the same technique in different conditions, are predicted by theory, and are often greater than an order of magnitude. Many of these errors, particularly in passive systems, are a result of incorrect application of the electrochemical techniques, rather than the techniques themselves being inadequate for probing the behavior of the steel/ concrete system. When electrochemical techniques are used correctly, they can provide fast, quantitative, and trustworthy data, although not precisely exact, regarding the corrosion rate of steel in concrete.

Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

“…Although the drawbacks of the technique are well known, it is widely applicable for fast evaluation of electrochemical behavior ͑for example, deriving R p as in this study͒ for reinforced concrete or mortar systems. 10,21,38,39 The arising errors can be minimized by establishing a correct sweep rate and waiting time during the measurements, e.g., potentiodynamic measurement using a 2.5-10 mV/min sweep rate 17,21,27,29,40 gives reliable results. The aim of this contribution is to investigate the applicability and reliability of a combination of techniques, which at first take into consideration both materials in a reinforced concrete system, i.e., the bulk cement-based material and the steel surface.…”

“…7,13,[16][17][18][19][20] A recent study 21 presents comprehensive information on the application of EC techniques in investigating the corrosion of steel reinforcement, emphasizing the fact that all known techniques are applicable and useful for such systems and the inevitable errors in deriving quantitative results are mainly due to inaccurate performance of the techniques but not the techniques themselves. [22][23][24] Generally, all EC techniques use simple models which might not always completely apply to all corrosion systems; therefore, the applicability of these techniques, especially in systems like reinforced cement-based materials, being relatively more complex, 25 are subject to certain limitations, as already reported and discussed in numerous works.…”

Estabilidad del estado pasivo del acero en morteros de ceniza volante activada

“…E corr is quickly and conveniently measured and for that reason one of the most widely used electrochemical parameters. Its main advantage is that it can reveal the likelihood of active steel corrosion (23,(28)(29)(30)(31)(32)(33), providing La Figura 3 (a, b y c) muestra la evolución de las i corr de los redondos de acero embebidos en el mortero de cemento Pórtland, y en los morteros de ceniza volante activada alcalinamente con las disoluciones N y NW respectivamente, sin cloruros y con la adición de un 2% de Cl -. Los puntos A y B indican los valores de tiempo a los cuales se varió las condiciones de humedad relativa a las que estuvieron expuestas las probetas (95%-30%-95% de HR) tal y como se indicó en el apartado experimental.…”

Electrochemical Response of AA7075-T651 Following Immersion in NaCl Solution

“…The frequency range determined by this approach yields results between 50Hz and 0.2Hz. A cautionary note should be made here to emphasize that the current transient resulting from a potentiostatic signal is influenced rather significantly by the electrolyte resistance (ohmic resistance, R Ω ) (18), thus the aforementioned approach is suited toward systems with negligible electrolyte resistance such as the case investigated here. Where potentiodynamic polarization was used, a potential scan rate of 1mV/s was employed.…”