Polarization resistance measurements of bars embedded in concrete with different chloride concentrations: EIS and DC comparison

Abstract

The experimental conditions for corrosion rate measurements of reinforcement by means of the polarization resistance technique, R p , in order to obtain reliable values (in accordance with the gravimetric losses simultaneously measured) must consider some factors as are: the need to subtract ohmic drop generated by the high resistivity of the concrete, the need to wait a certain time after application of the current, the use of a certain sweep rate in order to obtain a quasi-steady-state value of the conjugated variable (potential/current), the need to avoid the overlapping with other processes, and the need to use a correct B value in Stern formula. These experimental requirements should be optimized for the individual kinetic of each system. From time to time several papers are published wondering whether R p measurements in concrete are reliable. Present paper extends the study of the experimental conditions influence in the R p determination in order to look more in detail to the accuracy of R p technique. Several sweep rates in potentiodynamic tests, different waiting times with galvanostatic and potentiostatic pulses and different frequencies in electrochemical impedance spectroscopy, EIS, were tested in order to compare the most suitable parameters that provide correct values of the corrosion rate, I corr .

Chloride-induced corrosion of reinforcement in low-calcium fly ash-based geopolymer concrete

“…Corrosion parameters such as the open circuit corrosion potential (E corr ), polarization resistance (R p ) and Tafel constants have been measured and the obtained results were validated by comparing the gravimetric and electrochemical mass losses. Also, Gravimetric measurements were beneficial to calibrate R p measurements regarding finding an appropriate potential sweep rate range [38,39]. pH of the samples was measured as the passivity of steel bar depends on the pH of the concrete.…”

“…ZIR technique is very similar to the Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) technique, except that it is performed at a single frequency. Only 85% of the measured ohmic drop was compensated to avoid oscillation of the instrument [39,46]. IR compensation was always implemented before other electrochemical tests to take into account the effect of uncompensated electrolyte resistance (R e ) on the shape of polarization curves (or Tafel plots) and hence revising R p , Tafel constants and I corr .…”

Effect of Crack on Durability of RC Material under the Chloride Aggressive Environment

“…The voltage applied in EIS measurements is much smaller than those of LP and TPP measurements, which means EIS measurements display a smaller disturbance and better reproducibility of electrochemical systems than the others [35]. Therefore, EIS measurements can be performed continuously, while the others cannot because the error in a continuous test procedure can be very large.…”

Electrochemical Sensors for Monitoring the Corrosion Conditions of Reinforced Concrete Structures: A Review

“…The most common techniques used for R p measurements, to assess the i corr of steel in RCS, were galvanostatic [3,5,70,[146][147][148][149], potentiostatic pulses [17,136,150,151], cyclic voltammetry (conducted at very low scan rates) [151][152][153][154][155][156][157][158][159], and electrochemical impedance spectroscopy (EIS) [81,[160][161][162][163][164][165][166]. The method proposed by Stern and Geary in 1957 is based on the observation of the linearity of the polarization curve together with the corrosion potential.…”

“…It can be used to study an electrochemical system assuming that an electrical equivalent circuit (EEC) can represent the behavior of the steel embedded within the concrete [161,164,166,195,197,198,[206][207][208][209][210]. However, due to the heterogeneity of concrete, the analysis of the EIS results is challenging.…”