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.

What is claimed is: 
     
         1 . An anode assembly for galvanic cathodic protection of a reinforced concrete structure comprising:
 at least one sacrificial anode member;   a covering material consisting of a hydrophilic non-cementitious open-cell foam substantially covering the sacrificial anode member;   an activating salt designed to keep the sacrificial anode in an electrochemically active state within the open-cell foam covering material;   at least one elongated metallic conductor metallurgically bonded to the sacrificial anode.   
     
     
         2 . An anode assembly of  claim 1  wherein the sacrificial anode member is zinc or a zinc alloy. 
     
     
         3 . An anode assembly of  claim 1  wherein the sacrificial anode member is a high surface area configuration having an actual surface area from three to six times that of its superficial surface area. 
     
     
         4 . An anode assembly of  claim 1  wherein the hydrophilic open-cell foam is a phenolic resin. 
     
     
         5 . An anode assembly of  claim 1  wherein the hydrophilic open-cell foam is compressible. 
     
     
         6 . An anode assembly of  claim 1  wherein the activating salt within the hydrophilic open-cell foam is a deliquescent or hygroscopic material. 
     
     
         7 . An anode assembly of  claim 1  wherein the activating salt within the hydrophilic open-cell foam is lithium nitrate, lithium bromide, or combinations thereof. 
     
     
         8 . An anode assembly of  claim 1  wherein the activating salt within the hydrophilic open-cell foam is present in the amount of between about 0.05 grams and about 1 gram per cubic centimeter. 
     
     
         9 . An anode assembly of  claim 1  wherein the hydrophilic open-cell foam is impregnated with a gel. 
     
     
         10 . An anode assembly of  claim 9  wherein the gel has a viscosity ranging from 1 to 500 pascal-seconds (Pa·s). 
     
     
         11 . An anode assembly of  claim 9  wherein the gel is based on the agent agar-agar. 
     
     
         12 . An method for galvanic cathodic protection of a reinforced concrete structure, said method including:
 providing at least one sacrificial anode member;   substantially covering the sacrificial anode member with a covering material consisting of a hydrophilic non-cementitious open-cell foam;   impregnating the open cell foam, either before or after substantially covering the anode member, with an activating salt designed to keep the sacrificial anode in an electrochemically active state within the open-cell foam covering material;   metallurgically bonding at least one elongated metallic conductor to the sacrificial anode, and;   connecting the elongated metallic conductor to a ferrous reinforcing member within surrounding concrete, thus allowing protective current to flow.   
     
     
         13 . The method according to  claim 12  utilizing an open-cell foam comprising a phenolic resin. 
     
     
         14 . The method according to  claim 12  wherein the open-cell foam is compressible. 
     
     
         15 . The method according to  claim 12  utilizing an activating agent selected from the group consisting of lithium nitrate, lithium bromide and mixtures thereof in an amount of between about 0.05 gram and about 1 gram per cubic centimeter of foam. 
     
     
         16 . The method according to  claim 15  further impregnating the foam with a gel. 
     
     
         17 . The method according to  claim 16  wherein the gel is based on the agent agar agar. 
     
     
         18 . The method according to  claim 16  wherein the gel has a viscosity ranging from about 1 to about 500 pascal-seconds (Pa·s). 
     
     
         19 . The method according to  claim 12  wherein the activating agent is a hygroscopic or deliquescent material.