Corrosion behavior of iron plates in cementitious solution at 80°C in anaerobic conditions

David Pally (1) , Patrick Le Bescop (1) , Michel Schlegel (2) , Frédéric Miserque (3) , Laure Chomat (1) , Delphine D. Neff (4) , Valérie L'Hostis (5)

1 SECR - Service d'Etudes du Comportement des Radionucléides
2 SEARS - Service d'études analytiques et de réactivité des surfaces
3 SCCME - Service de la Corrosion et du Comportement des Matériaux dans leur Environnement
4 LAPA - UMR 3685 - Laboratoire Archéomatériaux et Prévision de l'Altération
5 DPC - Département de Physico-Chimie

Iron was corroded in anoxic cementitious (pH 13.2) media (filtered porewater or cement slurry) at 80°C; corrosion products were investigated by microscopic techniques. A thin film of magnetite (Fe$_3$O$_4$) formed during the first immersion days. For longer immersion times (90 days) in cement slurry, hydroandradite (HA) (Ca$_3$(Fe$^{3+}$)$_2$(SiO$_4$)$_y$(OH)$_4$$_(3-y)$) formed a dense outer layer and an heterogeneous inner layer. A thin oxide layer is always observed in contact with metal and is believed to correspond to a protective barrier. Our results suggest that in the conditions of the Belgian Supercontainer for radioactive waste disposal, a passive layer slowing down corrosion can form.

Keywords: Iron; Concrete; Alkaline corrosion; Magnetite; Hydroandradite; Barrier layer

Domains: Chemical Sciences; Inorganic chemistry

David Pally, Patrick Le Bescop, Michel Schlegel, Frédéric Miserque, Laure Chomat, et al.. Corrosion behavior of iron plates in cementitious solution at 80°C in anaerobic conditions. Corrosion Science, 2020, 170, pp.108650. ⟨10.1016/j.corsci.2020.108650⟩. ⟨cea-02927606⟩