Corrosion of horizontal bars in concrete and method to delay early corrosion

Tarek Uddin Mohammed, Hidenori Hamada

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A detailed investigation was carried out to clarify the macrocell and microcell corrosion of horizontally oriented steel bars in concrete. To find an effective way to control corrosion of horizontal bars in concrete, three alternatives, such as the application of a cement paste coat over the steel bars, revibration, and the use of expansive admixture were studied. For this, prism specimens 200 mm in length, 150 mm in width, and 500 mm in depth were made with steel bars at three horizontal levels at 100, 250, and 400 mm from the bottom. The specimens were exposed to artificially-created wetting and drying cycles using natural seawater. Electrochemical and physical evaluations of corrosion, chloride ingress, and SEM investigation on the steel-concrete interfaces were carried out. A porous steel-concrete interface under the bottom half of the steel bar was found. The weaker interface caused early corrosion under the bottom half of the steel bar. Generally, the macro-cornosion cell is fanned between the top half (anode) and bottom half (cathode) of the steel bar. A significant amount of microcell corrosion was found over the bottom half. The application of a cement paste coat over the steel bars before embedding into concrete was found to be an effective way to delay early corrosion under the bottom half of the steel bars. The use of an expansive admixture was also found as another alternative. No improvement of steel-concrete interface was obtained by revibration; revibration creates more corrosion over the steel bars.

Original languageEnglish
Pages (from-to)303-311
Number of pages9
JournalACI Materials Journal
Volume103
Issue number5
Publication statusPublished - Sep 2006

All Science Journal Classification (ASJC) codes

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

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