Effect of stray current on corrosion behavior of reinforcing steel: importance of cell geometry and orientation with respect to the electrical field
Zhipei Chen (TU Delft - Materials and Environment)
Dessi Koleva (TU Delft - Materials and Environment)
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Abstract
Stray current circulating in reinforced concrete structures may initiate corrosion or accelerate existing corrosion processes on embedded reinforcement. In some cases, the range of dangerous or unwanted interactions of stray currents under favorable conditions (environment), is much broader than is generally recognized. All these show that investigation of the effects of stray current on the corrosion behavior of steel is necessary and significant.
In this work, the tested level of stray current was 3 mA/cm2, and the type of samples were reinforced mortar cubes (40 mm×40 mm×40 mm). To investigate the corrosion behavior of embedded steel undergoing stray current, the evaluation indicators adopted were OCP (Open Circuit Potential), Polarization resistance (Rp) derived through LPR (Linear Polarisation Resistance), and electrochemical parameters recorded through EIS (Electrochemical Impedance Spectroscopy) and PDP (Potentio-Dynamic Polarization). The recorded electrochemical response aimed to elucidate the importance of cell geometry i.e. the effect of steel orientation with respect to the electrical field (placed parallel or orthogonal to the current direction). It was found that the geometrical position of the steel bar is of significant importance and determines the level of stray current-induced degradation.