Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Dokumenttyp
- Zeitschriftenartikel (1)
- Vortrag (1)
Sprache
- Englisch (2)
Referierte Publikation
- nein (2)
Schlagworte
- Corrosion product (2) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (1)
This paper deals with the initiation and propagation of corrosion in mortar specimens precracked under mechanical loading and carbonated in climate accelerated conditions (50 % CO2–65 % RH)for 15–23 weeks. Mechanical loading led to transverse macro-cracks and damage at the steel-mortar interface characterized by micro-cracks (cover controlled cracking) which favour the carbonation of crack walls and the interface with the steel bar. Wetting–drying cycles performed after carbonation favoured corrosion initiation all along the steel bar because of the carbonated interface and corrosion propagation because of the creation of corrosion cracks which appear to develop from the micro-cracks induced by the mechanical load. Results also show that rust develops all around the perimeter of the carbonated steel bar but that the corrosion layer is thicker in the lower half surface of the reinforcement than that observed in the upper half. Results indicate that the distribution and composition of corrosion products depend on the thickness of the rust layer and that the multilayered structure of rust depends mainly on its thickness.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea can also cause MIC by directly withdrawing electrons from the iron surface for methanogenesis. However, the mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite, a by-product of methanogenesis, (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.