Monitoring the Corrosion of Steel in Concrete Exposed to a Marine Environment

Andraž Legat,Nina Gartner,Tadeja Kosec

doi:10.3390/ma13020407

Andraž Legat, Nina Gartner + Show 1 more

Open Access

https://doi.org/10.3390/ma13020407

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Abstract

Reinforced concrete structures require continuous monitoring and maintenance to prevent corrosion of the carbon steel reinforcement. In this work, concrete columns with carbon and stainless steel reinforcements were exposed to a real marine environment. In order to monitor the corrosion processes, two types of corrosion probes were embedded in these columns at different height levels. The results from the monitoring of the probes were compared to the actual corrosion damage in the different exposure zones. Electrical resistance (ER) probes and coupled multi-electrodes (CMEs) were shown to be promising methods for long-term corrosion monitoring in concrete. Correlations between the different exposure zones and the corrosion processes of the steel in the concrete were found. Macrocell corrosion properties and the distribution of the separated anodic/cathodic places on the steel in chloride-contaminated concrete were addressed as two of the key issues for understanding the corrosion mechanisms in such environments. The specific advantages and limitations of the tested measuring techniques for long-term corrosion monitoring were also indicated. The results of the measurements and the corrosion damage evaluation clearly confirmed that the tested stainless steels (AISI 304 and AISI 304L) in a chloride-contaminated environment behave significantly better than ordinary carbon steel, with corrosion rates from 110× to 9500× lower in the most severe (tidal) exposure conditions.

Highlights

Reinforced concrete structures are not as long-lasting as was generally considered up until the1970s [1,2]
The thickness reduction on the carbon steel electrical resistance (ER) probes in the individual zones of exposure is almost identical in both equipped columns (C11 and C12); only the results from one column are presented (Figure 3a)
The initiation was observed from the increased thickness reduction (∆d), which is directly related to the corrosion rate

Summary

Introduction

Reinforced concrete structures are not as long-lasting as was generally considered up until the1970s [1,2]. Reinforced concrete structures are not as long-lasting as was generally considered up until the. The economic, ecological, and safety aspects of this led to the beginning of intensive research to understand the mechanisms of corrosion in concrete, and to find new technologies and materials, with the aim of improving the durability of reinforced concrete structures [1,4]. The main two initiators of corrosion in concrete are carbonation and the presence of chloride ions [2,3,5]. A lot of studies defining the chloride threshold level (CTL, i.e., the critical chloride concentration causing corrosion initiation) values in concrete have been published and the reported results scatter over more than two orders of magnitude when expressed as the total chloride content by cement weight [3,7]. Angst et al [8] conducted

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