Investigating the spatial development of corrosion of corner-located steel bar in concrete by X-ray computed tomography

Research output: Contribution to journalArticle

Abstract

In this paper, the chloride-induced corrosion progression of a corner located steel bar in concrete is investigated by X-ray computed tomography (i.e., X-CT). Corrosion of steel bar is accelerated by placing the reinforced specimen in a wetting and drying cyclic corrosive environment, rather than by the impressed current method. 3D X-CT images are obtained and processed to characterize the different material phases, consisting of, steel bar, mortar, corrosion products and voids/cracks. The corrosion products expansion and concrete cracking are analysed and discussed. It has been found that pitting corrosion is prone to appear around the voids close to the steel bar, mainly due to the pre-existing supply of oxygen and moisture. In addition, a distinct transverse crack has been identified which is caused by non-uniform corrosion along the reinforcing steel bar. Within the cross-section, corrosion has also been found non-uniformly distributed, with the maximum rust layer pointing to the corner edge of the sample. Moreover, the corrosion rust distributions are used to parameterize a recently developed non-uniform corrosion model. This experimentally validated non-uniform corrosion model can be applied to corrosion-induced concrete cracking problems with confirmed accuracy. The combination of the use of wetting and drying cyclic corrosive environment and the X-CT scanning can provide a new method to the non-destructive investigation of corrosion process, rust distribution and corrosion-induced concrete cracking in the reinforced concrete structures.
LanguageEnglish
Pages177-189
Number of pages13
JournalConstruction and Building Materials
Volume221
Early online date14 Jun 2019
DOIs
Publication statusPublished - 10 Oct 2019

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Steel
Tomography
Concretes
Corrosion
X rays
Caustics
Wetting
Drying
Cracks
Pitting
Mortar
Concrete construction
Reinforced concrete
Chlorides
Moisture

Keywords

  • X-ray CT
  • phase characterization
  • non-uniform corrosion
  • wetting and drying cyclic accelerated corrosion
  • rust distribution model
  • concrete structures

Cite this

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title = "Investigating the spatial development of corrosion of corner-located steel bar in concrete by X-ray computed tomography",
abstract = "In this paper, the chloride-induced corrosion progression of a corner located steel bar in concrete is investigated by X-ray computed tomography (i.e., X-CT). Corrosion of steel bar is accelerated by placing the reinforced specimen in a wetting and drying cyclic corrosive environment, rather than by the impressed current method. 3D X-CT images are obtained and processed to characterize the different material phases, consisting of, steel bar, mortar, corrosion products and voids/cracks. The corrosion products expansion and concrete cracking are analysed and discussed. It has been found that pitting corrosion is prone to appear around the voids close to the steel bar, mainly due to the pre-existing supply of oxygen and moisture. In addition, a distinct transverse crack has been identified which is caused by non-uniform corrosion along the reinforcing steel bar. Within the cross-section, corrosion has also been found non-uniformly distributed, with the maximum rust layer pointing to the corner edge of the sample. Moreover, the corrosion rust distributions are used to parameterize a recently developed non-uniform corrosion model. This experimentally validated non-uniform corrosion model can be applied to corrosion-induced concrete cracking problems with confirmed accuracy. The combination of the use of wetting and drying cyclic corrosive environment and the X-CT scanning can provide a new method to the non-destructive investigation of corrosion process, rust distribution and corrosion-induced concrete cracking in the reinforced concrete structures.",
keywords = "X-ray CT, phase characterization, non-uniform corrosion, wetting and drying cyclic accelerated corrosion, rust distribution model, concrete structures",
author = "Xun Xi and Shangtong Yang",
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N2 - In this paper, the chloride-induced corrosion progression of a corner located steel bar in concrete is investigated by X-ray computed tomography (i.e., X-CT). Corrosion of steel bar is accelerated by placing the reinforced specimen in a wetting and drying cyclic corrosive environment, rather than by the impressed current method. 3D X-CT images are obtained and processed to characterize the different material phases, consisting of, steel bar, mortar, corrosion products and voids/cracks. The corrosion products expansion and concrete cracking are analysed and discussed. It has been found that pitting corrosion is prone to appear around the voids close to the steel bar, mainly due to the pre-existing supply of oxygen and moisture. In addition, a distinct transverse crack has been identified which is caused by non-uniform corrosion along the reinforcing steel bar. Within the cross-section, corrosion has also been found non-uniformly distributed, with the maximum rust layer pointing to the corner edge of the sample. Moreover, the corrosion rust distributions are used to parameterize a recently developed non-uniform corrosion model. This experimentally validated non-uniform corrosion model can be applied to corrosion-induced concrete cracking problems with confirmed accuracy. The combination of the use of wetting and drying cyclic corrosive environment and the X-CT scanning can provide a new method to the non-destructive investigation of corrosion process, rust distribution and corrosion-induced concrete cracking in the reinforced concrete structures.

AB - In this paper, the chloride-induced corrosion progression of a corner located steel bar in concrete is investigated by X-ray computed tomography (i.e., X-CT). Corrosion of steel bar is accelerated by placing the reinforced specimen in a wetting and drying cyclic corrosive environment, rather than by the impressed current method. 3D X-CT images are obtained and processed to characterize the different material phases, consisting of, steel bar, mortar, corrosion products and voids/cracks. The corrosion products expansion and concrete cracking are analysed and discussed. It has been found that pitting corrosion is prone to appear around the voids close to the steel bar, mainly due to the pre-existing supply of oxygen and moisture. In addition, a distinct transverse crack has been identified which is caused by non-uniform corrosion along the reinforcing steel bar. Within the cross-section, corrosion has also been found non-uniformly distributed, with the maximum rust layer pointing to the corner edge of the sample. Moreover, the corrosion rust distributions are used to parameterize a recently developed non-uniform corrosion model. This experimentally validated non-uniform corrosion model can be applied to corrosion-induced concrete cracking problems with confirmed accuracy. The combination of the use of wetting and drying cyclic corrosive environment and the X-CT scanning can provide a new method to the non-destructive investigation of corrosion process, rust distribution and corrosion-induced concrete cracking in the reinforced concrete structures.

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