Anode assembly for cathodic protection

Abstract

The cathodic protection of a reinforced concrete structure utilizes sacrificial anodes such as aluminum or zinc as well as alloys thereof. Each anode is embedded or substantially covered in a material consisting of a hydrophilic non-cementious open-cell foam. An activating agent such as one or more lithium salts is contained within the cells of the foam to maintain the anodes in an electrochemically active state. The activating agent may be immobilized in the cells using an aqueous gel such as agar. One or more metallic conductors electrically connect the anodes to the metal reinforcing members.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of and priority to provisional patent application Ser. No. 61 / 849,291, filed on Jan. 24, 2013, entitled “ANODE ASSEMBLY FOR CATHODIC PROTECTION which is incorporated herein in its entirety by reference.BACKGROUND OF THE INVENTION[0002]1. Technical Field[0003]This invention generally relates to the field of galvanic cathodic protection of steel embedded in concrete structures, and is particularly concerned with the performance of embedded sacrificial anodes, such as zinc, aluminum, and alloys thereof.[0004]2. Description of Prior Art[0005]The problems associated with corrosion-induced deterioration of reinforced concrete structures are now well understood. Steel reinforcement has generally performed well over the years in concrete structures such as bridges, buildings, parking structures, piers, and wharves, since the alkaline environment of concrete causes the surface of the steel to “passivate” such th...

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Benefits of technology

[0025]The present invention also relates to a method of cathodic protection of reinforced concrete, and more particularly, to a method of improvi...

Problems solved by technology

Unfortunately, since concrete is inherently somewhat porous, exposure to salt (NaCl) over a number of years results in the concrete becoming contaminated with chloride ions.

When the chloride reaches the level of the reinforcing steel, and exceeds a certain threshold level for contamination, it destroys the ability of the concrete to keep the steel in a passive, non-corrosive state.

When this tensile force exceeds the tensile strength of the concrete, cracking and delaminations develop.

With continued corrosion, freezing and thawing, coupled with traffic pounding, the utility or integrity of the structure is finally compromised and repair or replacement becomes necessary.

Reinforced concrete structures continue to deteriorate at an alarming rate.

Structurally deficient bridges are those that are closed, restricted to light vehicles only, or that require immediate rehabilitation to remain open.

The damage on most of these bridges is caused by corrosion.

Of these techniques, only cathodic protection is capable of controlling corrosion of reinforcing steel over an extended period of time without complete removal of the salt-contaminated concrete.

This type of cathodic protection has been generally successful, but problems have been reported with reliability and maintenance of the power supply.

Problems have also been reported related to the durability of the anode itself, as well as the concrete immediatel...

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