Carbonation-induced corrosion: Investigation of the corrosion onset

Abstract

There are different views in the literature on the relationship between the location of the carbonation front and the onset of reinforcement corrosion. Theoretically, corrosion starts when the carbonation front reaches the reinforcement, but some authors have observed an apparent earlier start of corrosion. In the present study, mortar samples with and without reinforcement were exposed up to 22 weeks to 20 °C, 60% RH and 1.5% CO2. The state of the reinforcement was monitored by potential measurements of potential. The carbonation of the bulk and the mortar-steel interface was detected by spraying a pH indicator on a freshly split or cut surface.Good agreement was found between low potential values (compared to reinforcement in the passive state) and the carbonation of the mortar-steel interface. A difference in the spatial variation of the carbonation depth was observed between plain and reinforced samples. The differences found in the literature between the location of the carbonation front and the corrosion onset can probably be explained by the spatial variation of the carbonation depth in the vicinity of the reinforcement.

Macrocell corrosion in carbonated Portland and Portland-fly ash concrete - Contribution and mechanism

“…The OCP values were not affected by the casting position. In a previous investigation [2], we found in samples of comparable size casting position dependent microstructural defects in terms of crack patterns in the vicinity of the reinforcement. Such defects may have changed the local conditions at the anode and influenced the corrosion process.…”

“…Reinforcement embedded in sound concrete is covered with a thin oxide layer, which protects the reinforcement from further corrosion [1]. Once the carbonation front reaches the reinforcement and the concrete-steel interface is carbonated, active corrosion can develop [2].…”

“…Carbonation is assumed to lead to microcell corrosion in the depassivated fraction of the reinforcement. However, parts of the reinforcement will remain passive due to the spatial variation of the carbonation front [2], or the reinforcement layout. This leads to macrocell corrosion in addition to microcell corrosion [1].…”

A study on the effect of presence of CeO2 and benzotriazole on activation of self‐healing mechanism in ZrO2 ceramic‐based coating

“…Corrosion is one of the most destructive processes which result in metals degradation and has huge yearly economic damages to the industry. Corrosion is a destructive attack to the metal through chemical or electrochemical reactions with the environment that includes anodic and cathodic reactions . Damages made by corrosion are one of the most important degradation processes, which must be prevented by active parties in order to reduce the investment damages and increase the security of transit/air transports .…”

“…Corrosion is a destructive attack to the metal through chemical or electrochemical reactions with the environment that includes anodic and cathodic reactions. 1,2 Damages made by corrosion are one of the most important degradation processes, which must be prevented by active parties in order to reduce the investment damages and increase the security of transit/air transports. 3,4 Active corrosion resistance aims at reducing the corrosion extent when the main barrier (coating matrix) is damaged and the corrosive species are in contact with the substrate.…”