Crack closure and rehabilitation of chloride contaminated reinforced concrete structures

Abstract

Apparatus to electrodeposit a chemical composition into cracks in concrete filling same is disclosed. The apparatus is comprised of a dam (reservoir) which is placed over the crack to be filled, an electrolyte which is received within the dam (reservoir), a direct current power source and an electrode which is received within the electrolyte and acts as an anode. The steel reinforcing rods within the concrete act as the cathode. Application of direct current from the power source to the electrode and the reinforcing rods causes the electrodeposition of a chemical composition into the crack filling same and the repassivation of the reinforcing rods within the concrete.

Description

TECHNICAL FIELD [0001] The present invention relates, in general, to repairing cracks in chloride contaminated reinforced concrete structures and, more particularly, to the application of technology to electrodeposit a chemical composition into a crack to fill the crack and to repassivate the steel reinforcing rods in the concrete structure. BACKGROUND ART [0002] Steel reinforcing rods contained within concrete are protected against corrosion by the alkalinity of the cement within the concrete. The cement contains alkali, alkali earth, metal oxides and hydroxides that typically result in concrete having a pH of between 12 and 14 depending upon the source of the cement and its age. In a highly alkaline environment, the steel reinforcing rods are passivated by the formation of a surface oxide film that protects the steel from corrosion. This protective oxide film is relatively stable at pH values greater than approximately 12.5 in a chloride free environment. The pH value required to ...

AI Technical Summary

Benefits of technology

[0007] The present invention solves the problems associated with the prior art approaches to repair cracks in chloride contaminated reinforced concrete structures and other problems by applying technology to electrodeposit a chemical composition into the crack filling same. Such electdeposition requires the use of a dam (reservoir) which is placed over the crack to be filled, an electrolyte received with the dam (reservoir), a direct current power source and a steel mesh electrode which is received within the electrolyte and acts as an anode. Th

Problems solved by technology

If this protective film is broken, corrosion can commence on the steel reinforcing rods.

Once the pH of the concrete is below 9.5, the protective oxide film starts to break down resulting in the commencement of corrosion of the steel reinforcing rods and the deterioration of the concrete structure.

In addition, variations in the repair should be limited and predictable over time and the repair should not deteriorate over time.

Even though electrochemical approaches have been utilized to minimize or eliminate future corrosion of the steel reinforcing rods in concrete, such an approach does not fill the cracks within same.

Such an approach, however, requires the crack to be immersed completely in an electrolyte solution.

In many instances, immersion of the crack into an electrolyte solution is not possible.

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