Corrosion-Inhibitor Efficiency Control: Comparison by Means of Different Portable Corrosion Rate Meters

Abstract

INTRODUCTION

A critical examination of corrosion rate measurement techniques applied to reinforcing steel in concrete

“…The results clearly show an overestimation of corrosion rates (∼1 µA/cm 2 ) given by the galvanostatic pulse technique for blocks without admixed chlorides; that is, passive reinforcements. This overestimation is in agreement with reported data from the literature [9,14,15,19,[43][44][45] and is believed to be the result of several assumptions used by the device used. The galvanostatic pulse device uses a similar current confinement procedure for both active and passive corrosion states, which is an assumption that has been shown to be inaccurate due to the high resistance to polarization exhibited by passive steel.…”

“…The third reason for the overestimation of corrosion rates for passive reinforcement, and perhaps the most significant one, is the short measurement duration used. The measurement time for the device that was used in this study was 10 s, which is considerably smaller than the time required for passive electrodes to reach quasi‐steady‐state conditions, under the current applied by the device (25 μA), as shown by Martinez et al This leads to an underestimation of R p, and further contributes to the overestimation of i corr , along with the other sources of errors.…”

“…The assumption that there exists a linear relationship between the applied polarization (Δ E ) and the corresponding current (Δ I ) might not always be correct, particularly for cases in which the potential shift is not controlled as in the case of the galvanostatic pulse technique. Measurement durations and scan rates can affect the polarization resistance obtained by these techniques considerably. For example, galvanostatic pulse technique might provide significant errors when short measurement durations are used because the potential shift measured in such durations (before reaching quasi‐steady‐state conditions) is not only related to the polarization resistance but also the double‐layer capacitance at the electrode surface A number of different methods can be used to compensate for ohmic resistance (commonly known as IR‐drop).…”

“…For example, galvanostatic pulse technique might provide significant errors when short measurement durations are used because the potential shift measured in such durations (before reaching quasi-steady-state conditions) is not only related to the polarization resistance but also the double-layer capacitance at the electrode surface. [19]…”

Efficiency of Amino Alcohols as Corrosion Inhibitors in Reinforced Concrete

“…At pH > 10.3 a protective layer of metalhydroxide is formed, which, however, is not completely insoluble. This hydroxide film can be stabilized by adsorption of 2-ethylaminoethanol on the hydroxylated surface and presumably by chelation of the ferrous ion [12,13]. An amino alcohol corrosion inhibitors can be mixed within the fresh concrete (admixture inhibitor), or can be applied on the surface of existing concrete structures.…”