Impact of Artificial Corrosion Technique under Variable Acceleration on Morphological Efficacy in Reinforced Concrete Elements

Abstract

The popularity of artificially accelerated methodologies for inducing corrosion in reinforced concrete (RC) elements has increased exponentially over recent decades due to their ability to achieve broad damage spectra within practical timespans. However, because of the time constraints often associated with experimentation, large volumes of data are obtained through excessively accelerated applications, potentially compromising the efficacy of the resulting corrosion byproducts, morphology, crack behavior, and system behavior. This paper experimentally studies the effects of the degree of acceleration on the corrosion morphology, sectional properties, crack distribution, and structural performance of laboratory-scale and large-scale RC elements. Two experimental phases are considered: a small laboratory-scale phase consisting of 24 RC cylinders and a large-scale phase involving eight circular RC columns tested under cyclic shear loading. Both phases investigate two variations of the impressed-current method for achieving artificial corrosion damage at varying current densities. The impressed-current method is divided into constant saturation and wet-dry phasing. Analyses are conducted from the local morphological scale to the global structural response and cyclic behavior of RC columns. The results emphasize that a maximum current density of 200 μA/cm2 should be implemented to ensure realistic corrosion morphologies and crack behavior. Wet-dry phasing effectively improves key sectional parameters associated with naturally occurring localized patterns, including radius of gyration, maximum eccentricity, and area pitting factor. Columns subjected to wet-dry phasing at severe levels demonstrated more significant reductions in ultimate deflection and peak shear capacity due to measurable increases in localized pitting corrosion. The final failure mechanism of columns with low amounts of corrosion was not impacted by technique or current density. This article aims to provide useful experimental information on the negative side effects of simulating corrosion in reinforced concrete (RC) in the laboratory too quickly. Because of the constant time and resource restrictions associated with experiments, the process of artificially creating corrosion in RC members is usually done too quickly. Overaccelerating the process leads to unrealistic corrosion and cracking patterns, which can negatively affect many of the results the experiments are trying to investigate in the first place. The results from this study found that increasing the speed of corrosion led to corrosion patterns that resemble naturally occurring corrosion less. The chosen technique to artificially corrode an RC member can also affect the realisticness of the final corrosion patterns, cracking patterns, and ultimate strength. From this investigation, a periodic wetting and drying technique produced the most realistic corrosion patterns, and a limit of 200 μA/cm2 was suggested for future experimental programs.