Reduction of chloride level in reinforced concrete by cathodic polarization technique

Abstract EN

The premature deterioration of concrete structures after 5-10 years of service has become a major problem during the past few decades.

The economic loss due to the corrosion of metals in concrete structures has been estimated at billions of dollars per year [I].

The role of chloride is very significant in the corrosion of reinforced concrete structures.

This corrosion can be minimized by bringing down the chloride pollution level within the concrete.

The tolerable limit of chloride varies with the pH of concrete.

Concrete with normal alkaline pH can tolerate up to 1000 ppm [2], In this study, use of an electrochemical technique to remove or reduce the chloride content in reinforced concrete structures is discussed.

Impressing current to increase the mobility of chloride ions towards the solution on the surface from the inside of concrete can bring down the chloride contamination to well within the above limit.

Different current densities for a period of 200 hours were applied continuously and the critical current for maximum removal of chloride has been identified.

The change in the solution chemistry of the electrolyte used for this purpose was monitored at an interval of 25 hours.

A rigorous analysis of the concrete in terms of pH and chloride content was also carried out.

Potentials of steel embedded in concrete were monitored before, during, and after polarization.

Cathodic polarization technique was found to be useful for removal of chloride from concrete structures.

A current density of 1A/m2 was found to be critical for maximum chloride removal.