Investigation of stone-hard-soil formation from AC corrosion of cathodically protected pipeline

Andreas Junker*, Louise Josefine Belmonte, Nick Kioupis, Lars Vendelbo Nielsen, Per Moller

*Corresponding author for this work

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A stone-hard-soil structure was observed on a metallic pipeline under cathodic protection and subject to alternating current corrosion at a coating defect. Using X-ray diffraction, energy dispersive X-ray spectroscopy, ion-chromatography and inductively coupled plasma optical emission spectroscopy, the stone-hard-soil was characterized as being enriched in NaCl. Local alkalization following the cathode reactions caused precipitation of calcite, believed to be partly responsible for the stability of the structure. Very close to the corrosion site at the epicenter, calcite and quartz was depleted, possibly owing to an extremely high pH. Formation of cement-like minerals and corrosion products is observed.
Original languageEnglish
JournalMaterials and Corrosion
Issue number9
Pages (from-to)1170-1179
Publication statusPublished - 2018


  • Alternating current (AC)
  • Calcareous deposition
  • Carbon steel
  • Cathodic protection
  • Pipeline
  • X-ray diffraction

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