Effects of initial defects within mortar cover on corrosion of steel and cracking of cover using X-ray computed tomography

Xiaogang Zhang, Guiqin Zuo, Shazim Ali Memon, Feng Xing, Hongfang Sun

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


In actual reinforced concrete structures, plenty of initial defects exist, which may greatly influence the behavior of steel corrosion and cracking within concrete cover. Thus, this paper presents an experimental investigation into the effects of initial defects within mortar cover on the corrosion of a steel bar in mortar and on the cracking of mortar cover using X-ray computed tomography. The influence of initial defects with mortar cover at three different positions i.e. interface, middle and surface was investigated for 5%, 30% and 55% corrosion levels of steel. From experimental investigations, it was found that the specimen with interface defect has significant accumulation of corrosion products. The position of cracking within mortar cover induced by steel corrosion was examined. At least one crack connected steel with the initial defects or reached close to the defect. These cracks formed the basis of the development of other cracks. The cracking level was defined in terms of the number of cracks and the volumes of total cracks and followed the sequence of S-SF > S-MD > S-IF, which is consistent with the sequence of volume expansion ratio of steel. The degree of release of rusts was found to depend on the position of the initial defects i.e. the closer the initial defect is to the steel, the better would be the releasing effect of rusts. Finally, comparison between the external and internal corrosion parameters reflecting corrosion level was performed.

Original languageEnglish
Pages (from-to)265-277
Number of pages13
JournalConstruction and Building Materials
Publication statusPublished - Oct 30 2019


  • 3D
  • Corrosion induced cracking
  • Defects
  • Non-destructive
  • Steel corrosion

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science(all)

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