Macrocell Significance in Reinforced Concrete Slabs Exposed to a Marine Environment

Abstract

Chloride-induced corrosion damage often appears in reinforced concrete structures (RCS) when they are located in a marine environment. Despite many tools for inspecting corrosion in RCS being available, it is not always possible to use them because of accessibility problems; for instance, when analysing submerged or buried elements. Therefore, embedded monitoring systems have been developed. They allow detecting corrosion early. Nevertheless, these systems are based on sensors which remain electrically isolated of rebars, so the macrocell currents that take place between active and passive areas of reinforcement are ignored. This study demonstrates the significance of macrocell currents by monitoring corrosion on two slabs partially submerged in seawater. These slabs included some corrosion sensors that were isolated from, but also connected to slabs’ rebars to participate or not in macrocell processes. Corrosion monitoring lasted almost 250 days. In this case, the results show that the obtained values can underestimate corrosion damage by 20 times if only local corrosion is considered and macrocell processes are not taken into account.