Monitoring reinforcement corrosion of concretes designed for nuclear facilitie

Abstract

The facilities designed for the peaceful activities of nuclear energy are made with different materials, among them, reinforced concrete. This material, in addition to being structural, is a barrier for isolation and confinement from the environment of the radioactive materials. One of its degradation mechanisms is the corrosion of the reinforcement, a frequent cause of premature failure in service. Consequently, it is essential to study this degradation mechanism in formulations developed for this purpose, as well as the development and implementation of monitoring techniques.The objective of this work is to compare, from the corrosion of reinforcement point of view, two concrete formulations, one made with ordinary portland cement and the other with pozzolanic portland cement. Both formulations are candidate for some nuclear applications, such as the Low Radioactive Waste disposal facilities, whose durability requirement is higher than 300 years. The results of approximately four years of monitoring are presented. The parameters followed are: corrosion potential and corrosion rate of the reinforcements, electrical resistivity, oxygen flow, internal temperature and carbonation rate of concrete. These parameters were measured and monitored in reinforced concrete specimens by embedded sensors previously developed in our laboratory. Also, unreinforced specimens were prepared to measure the carbonation rate. The presence of reinforcements provides the possibility of monitoring directly on them the corrosion potential, the corrosion rate and electrical resistivity of concrete, using on-surface electrodes provided by a commercial instrument. This allows the comparison of the parameters monitored by embedded sensors and the on-surface electrodes.