Pull-out and bond degradation of steel rebars in ECE concrete
- Queen`s Univ., Kingston, Ontario (Canada)
It is demonstrated in this study that application of electrochemical chloride extraction (ECE) to reinforced concrete alters the pull-out strength and bond between the embedded high strength steel (HSS) and surrounding concrete. Concrete cubes were case using two chloride ion concentrations of 1.7% and 3.0% by weight of cement respectively, and reinforced axially with a central plain steel bar. Two cathodic current densities were used for the ECE studies, with 0.1M sodium borate electrolyte solution and inert titanium anode mesh. Axial pull-out tests were carried out within 24 hours of terminating treatment to investigate the differences in bond stress and bar slip behavior. ECE treated specimens showed significant reductions in pull-out strength, with the degradation in bond being dependent on the applied cathodic current density and initial chloride contamination. At an impressed current density of 3.0 A/m{sup 2}, the 1.7% Cl{sup {minus}} ions specimens showed about 58% loss in bond strength compared with about 44% for specimens premixed with 3.0% Cl{sup {minus}} ion. The bond strength reduction at an impressed current density of 1.0 A/m{sup 2} was about half the reduction at current density of 3.0 A/m{sup 2}. It is predicted the softening effect of the alkali ions on the cement silicate hydrates around the steel-concrete interface will have severe effect on concrete structures reinforced with HSS irrespective of their stress state. Also, concrete structures containing steel rebars with substantial corrosion product coverage are likely to experience pronounced cathodic disbondment during ECE application and within a few days of terminating the treatment.
- OSTI ID:
- 227997
- Journal Information:
- Cement and Concrete Research, Journal Name: Cement and Concrete Research Journal Issue: 2 Vol. 26; ISSN 0008-8846; ISSN CCNRAI
- Country of Publication:
- United States
- Language:
- English
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