An analytical model for anchor-mortar interface bonding based on electrochemical impedance spectroscopy

Abstract

Corrosion can lead to deterioration of the bonding properties at anchor-mortar interfaces, affecting the durability of the anchored structures. Therefore, it is essential to establish an accurate analytical model of the anchor-mortar interface bond to estimate the interface bond strength under corrosion. Steel corrosion occurs via electrochemical reactions, that is, anode and cathode formation in different potential zones on the steel surface, resulting in an electrical potential difference that facilitates constant cation migration and the generation of corrosion products with anions. In this study, electrochemical impedance spectroscopy, taking into account electrochemical theory, was carried out to analyse the kinetics of the electrode processes. Based on electrochemical parameters such as pore solution resistance and charge transfer resistance, a function relating electrochemical parameters to the material properties was established. The traditional theoretical model of a thick-walled cylinder was modified to obtain an analytical model of the bond strength of the anchor-mortar interface in pull-out damage mode under the effect of corrosion. The accuracy of the estimated values of the analytical model was verified via pull-out test results. The estimated values obtained from the analytical model were in good agreement with the test values, indicating that the model was able to describe the corrosion state at the anchor-mortar interface and estimate the interfacial bond without damaging the specimen.