Corrosion Monitoring of Reinforced Steel Embedded in Cement Mortar under Wet-And-Dry Cycles by Electrochemical Impedance Spectroscopy

Abstract

The primary objective of the present work is to measure the corrosion rate of reinforcing steel embedded in concrete structures in a simulated marine environment of high chloride concentration. The selection of a single frequency that corresponds to the solution resistance and single frequency that corresponds to the charge transfer resistance were performed and measurements were carried out in a relatively faster time. A total of seven cement mortar specimens were prepared. The effect of varying cover thickness (5-50 mm) and rebar distance (10-80 mm) on the electrical resistance of the concrete and corrosion rate of the steel was examined. To simulate the corrosion of reinforced concrete in a marine environment, cement mortars were exposed to 25 wet-dry cycles that involve an immersion for 8 h in 3 wt.% NaCl solution and drying time of 16 h under room temperature. Alternative current (AC) impedance measurements were carried out within a frequency range from 100 kHz to 1 mHz. Results show that the formation of rust layers on rebars has caused a significant decrease in the maximum phase shift to θ = −30 • . An accelerated corrosion rate of the rebars was observed during drying stage.

Electrochemical Deposition Treatment (EDT) as a Comprehensive Rehabilitation Method for Corrosion-Induced Deterioration in Concrete with Various Severity Levels

“…The instantaneous corrosion rate in Figure 7 was determined based on the approximate polarization resistance in Equation (7). The impedance values at the low and high frequencies (i.e., and ) were determined at 10 mHz and 10 kHz, respectively [ 34 ]. Figure 8 shows the variations of and used to calculate in Figure 7 .…”

“…In test phase 1, EDT was applied to the four concrete prisms after completion of the 13th cycle of the wetting-and-drying process (see Figure 4 a). The timing of the EDT was determined based on observations in the previous research [ 34 ]. It required at least 13 cycles of the wetting-and-drying process for the corrosion rate (=1/ R P , R P is polarization resistance of reinforced concrete samples) to exceed a criterion for the initiation of corrosion (i.e., failure of a passive film on the surface of a reinforcing steel) (4 × 10 −6 Ω −1 cm −2 ) [ 35 ].…”

“…In contrast, the three-electrode system used a rebar as a WE, a titanium mesh as a CE, and the silver chloride electrode (Ag/AgCl) as an RE. It was demonstrated that the two-electrode system is effective to measure the electrochemical impedance properties of concrete in the wet-and-dry cycling conditions [ 34 , 36 ]. For both the two- and three-electrode systems, AC impedance of concrete was measured by a potentiostat (Won-A tec.…”

“…It was demonstrated that this simplified approach is effective for rapid monitoring of the corrosion rate by EIS [ 34 , 39 ].…”

Anticorrosion Inhibition Behavior of Rhus Pentaphylla Fruit Extracts in (1 M) HCl against Carbon Steel and their Chemical Characterization using HPLC‐MS‐ESI

“…Electrochemical impedance spectroscopy (EIS) is a non-stationary method that provides information on the elementary steps involved in corrosion processes. [37,38] It is used to precisely determine the rate of corrosion even in the case where the metal is covered with a protective layer, to evaluate the rate of inhibition and the characterization of various corrosion phenomena, such as dissolution or passivation. [39] Electrochemical parameters and the inhibitor efficiency values of R.pentaphylla fruit (S1, S2), were gathered in Table 3 and Figure 7.…”