Initiation of chloride-induced corrosion in reinforced concrete – effects related to the steel

Background

Chloride-induced reinforcing steel corrosion is the leading cause for premature degradation of reinforced concrete structures worldwide. Being able to predict the initiation of chloride-induced corrosion of steel is crucial for service life modeling of concrete structures. The fundamental lack of knowledge of the relevant parameters governing corrosion initiation of steel in concrete inhibits devising reliable predictive models.

After 60 years with a concept based solely on the amount of chloride necessary for corrosion to start, this project attempts to provide a novel, materials science-based approach to investigate the initiation of corrosion of steel in concrete and identify additional key parameters.

Aims and objectives

This project seeks to improve the understanding of chloride-induced corrosion initiation in reinforced concrete, by systematically addressing the characteristics of the steel-concrete interface. To this aim, an Automated Local Electrochemical Characterization (ALEC) technique is developed to study influences related to the reinforcing steel surface. The ultimate aim of the project is to identify key parameters that influence the conditions and the locations where corrosion of steel in presence of chloride initiates.

Methodology

The original idea of the project is to use an Automated Local Electrochemical Characterization (ALEC) technique to study and characterize the local electrochemical behavior of the steel surface. The locally characterized steels are then submitted to corrosion initiation tests in simulated alkaline concrete pore solutions. The corrosion initiation characteristics, e.g. Ccrit, pitting potential, pitting location, and the local electrochemical measurements, e.g. open circuit potential, local pitting potential, corrosion current, are compared in order to determine which characteristics have a major influence on the corrosion initiation of steel in presence of chloride.

Some possible parameters influencing the electrochemical and corrosion behavior of the steel will be specifically studied, namely the effect of mechanical stresses and surface preparation.