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Section I

Investigation on Efficiency of Repairing and Retrofitting Methods for Chloride induced Corrosion of Reinforced Concrete Structures

Authors:

B.H.J. Pushpakumara ,

University of Ruhuna, LK
About B.H.J.
Rresearch Student, Department of Civil and Environmental Engineering, Faculty of Engineering
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Sudhira De Silva,

University of Ruhuna, LK
About Sudhira
Senior Lecturer, Department of Civil and Environmental Engineering, Faculty of Engineering,
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G.H.M.J. Subashi De Silva

University of Ruhuna, LK
About G.H.M.J.
Senior Lecturer, Department of Civil and Environmental Engineering, Faculty of Engineering
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Abstract

The corrosion of steel reinforcement bars is one of the major deterioration mechanisms of Reinforced Concrete (RC) structures. Once the corrosion signs appear on the concrete surface, it may be too late to prevent further corrosion. As a result, service life of RC structures would be reduced. Use of repairing and retrofitting methods at the appropriate time will contribute enormous saving of country budget, which is required for re-construction. This paper presents an experimental investigation of repairing and retrofitting methods for the RC structures corroded due to chloride attack. As repairing methods for delaminated areas of corroded RC structures, Fly Ash (FA) and Silica Fume (SF) mixed mortars were developed and their performances were evaluated. As retrofitting methods, Cathodic Protection (CP) and Electrochemical Chloride Extraction (ECE) were conducted. ECE method is similar to CP method except the anode was covered by Ca(OH)2 layer. RC beams with concrete of Grade 20 and reinforcement bars of 16 mm diameter were cast. Efficiency of both repairing and retrofitting methods was evaluated by measuring free and total chloride ion concentration and rust production. Efficiency of repairing and retrofitting methods was further evaluated by measuring resistivity and Rapid Chloride Permeability Test (RCPT) and current measurement, respectively. FA mixed mortar reduces the total chloride ion concentration near embedded steel reinforcement bars in concrete by 40% while SF mixed mortar reduces 25% compared to OPC mortar. FA and SF mixed mortars prevent the corrosion process by minimizing the diffusion of chloride ions into concrete. It was found that CP method removed around 49% of total Cl- while ECE method removed around 69% of total Cl- near the steel reinforcement of RC beams. Removing of total Cl- by ECE is grater (in 20%) than that of by CP method. Chloride contaminated concrete that is still sound can be retrofitted by using CP and ECE methods and the spalled and detached concrete can effectively be repaired by using FA mixed mortars.

DOI: http://dx.doi.org/10.4038/engineer.v46i4.6807

ENGINEER, Vol. 46, No.04, pp. 19-30, 2013

How to Cite: Pushpakumara, B.H.J., De Silva, S. & De Silva, G.H.M.J.S., (2013). Investigation on Efficiency of Repairing and Retrofitting Methods for Chloride induced Corrosion of Reinforced Concrete Structures. Engineer: Journal of the Institution of Engineers, Sri Lanka. 46(4), pp.19–30. DOI: http://doi.org/10.4038/engineer.v46i4.6807
Published on 21 Oct 2013.
Peer Reviewed

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