Cover-zone protective qualities under corrosive environments

Jaehwan Kim, W. John McCarter, Benny Suryanto

Research output: Contribution to journalArticle

Abstract

The protective qualities of the concrete cover-zone and the condition of the embedded steel (active/passive) surface were studied using reinforced concrete slabs subjected to intermittent wetting/drying. The cementitious binders used within the experimental programme comprised plain Portland cement (CEM I) and Portland cement partially replaced with fly-ash (FA) and ground granulated blast-furnace slag (GGBS) with water/binder (w/b) ratios of 0.4 and 0.6. The concrete surface was exposed to a 0.55 Molar (3.2%) chloride solution with the intermittent regime extending over a period of ∼400 days. Pairs of stainless steel electrodes were positioned within the cover-zone to monitor changes in electrical resistance/resistivity as chlorides migrated through the concrete, whereas macro-cell current and half-cell potential measurements were used to study corrosion initiation on the steel surface. In addition, at the end of the experimental programme, chloride profiling and gravimetric mass-loss measurements were obtained. For the analysis of electrical measurements, a normalisation method was employed to study chloride transport within the cover-zone. It was found that ongoing hydration (and resulting pore structure refinement) was the main factor for the increase in the bulk electrical resistance/resistivity of concrete and that chloride ingress was the main factor for the reduction in resistance/resistivity. The resistance/resistivity varied depending on the depth of the chloride penetration. It was shown that both binder type and w/b had a significant influence on the performance of the cover-zone and that the electrical properties of concrete could be developed as a candidate indicator of concrete performance.
Original languageEnglish
Article number101618
JournalJournal of Building Engineering
Volume33
Early online date2 Jul 2020
DOIs
Publication statusE-pub ahead of print - 2 Jul 2020

Keywords

  • Chloride-induced corrosion
  • Electrical resistivity
  • Half-cell potential
  • Macro-cell current
  • Reinforced concrete

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Architecture
  • Building and Construction
  • Safety, Risk, Reliability and Quality
  • Mechanics of Materials

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