Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-05-06
2001-02-27
Bell, Bruce F. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S196200, C204S196220, C204S196250, C204S196330, C205S734000, C264S239000, C264S299000, C264SDIG006
Reexamination Certificate
active
06193857
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the cathodic protection of steel in reinforced concrete employing a sacrificial anode, more particularly to an electrical connector for connecting the sacrificial anode to the reinforcing steel it is intended to protect and to a method for the installation of the anode.
BACKGROUND OF THE INVENTION
Sacrificial anodes are well known. To be effective the sacrificial anode is made of a metal which has a more negative electrode potential than the steel to be protected so that it will corrode in preference to the steel. Sacrificial anodes are described in European Patent No 0707667 and U.S. Pat. No. 5,292,411.
PROBLEM TO BE SOLVED BY THE INVENTION
To fulfill its purpose the sacrificial anode needs to be connected electrically to the steel to be protected. Metal conductors have been previously used for this purpose. Previously these metal conductors such as wires, have been attached to the steel reinforcement by drilling a hole in the reinforcement into which a self tapping screw is inserted. Alternative methods have involved the use of clips or clamps to secure the wire to the metal to be protected.
These methods have problems in that the drilling of holes and use of self tapping screws is time consuming and there is always a risk that the clips and clamps may be dislodged.
The present invention provides a solution to these problems by the use of a ductile elongated connector that is connected to the steel reinforcing element by winding the connector around the reinforcing element.
SUMMARY OF THE INVENTION
According to the present invention there is provided an assembly (and a method of utilization thereof for use in the cathodic protection of steel reinforcement in reinforced concrete. The assembly comprises: (i) An anode of a metal having a more negative electrode potential than steel (and adapted to be in electrical contact therewith); and (ii) An elongated electrical connector made of a ductile metal capable of being wound around a concrete reinforcing steel reinforcing element to be protected.
The elongated connector of the assembly may be in the form of at least one wire, and the anode may be in the form of a block cast around a portion of the length of the wire. For example the elongated connector may comprise a plurality of wires twisted together over a portion of their length, and the anode formed (e.g. cast) around the twisted portion. Preferably the wires are twisted together at a position intermediate their ends so that the wires extend outwardly from more than one side of the anode. The anode may be enclosed in a porous material which has been cast around it, the porous material containing an electrolytic solution whose pH is sufficiently high for corrosion of the anode to occur and passive film formation on the anode to be avoided when the anode is galvanically connected to a concrete steel reinforcement.
The invention also preferably comprises an assembly as described above in combination with a concrete steel reinforcing element, the assembly being connected to the reinforcing element (both physically and electrically) by winding the elongated connector around the reinforcing element.
According to another aspect of the present invention there is provided at least first and second wires twisted together at a position intermediate their ends to form a twisted portion. A block of anode material cast around the twisted portion, so that at least four wire arms extend outwardly from the block. And, wherein the wires are of ductile metal capable of wrapping around a concrete reinforcing steel reinforcing element. A cementitious material may also be cast around the anode, as described earlier.
According to another aspect of the present invention there is provided a method of making an assembly for use in the cathodic protection of steel reinforcement in reinforced concrete using an anode of a metal having a more negative electrode potential than steel, and an elongated electrical connector made of a ductile metal capable of being wound around a steel reinforcing element to be protected. The method comprises: (a) Melting the metal for the anode, so that it is in liquid form. (b) Placing a part of the length of the connector in a mold. And, (c) casting the anode from the liquid metal in the mold to form a block of metal around a portion of the length of the elongated electrical connector.
The method may further comprise (d) producing a liquid or semi-liquid mixture of a porous material containing an electrolytic solution having a pH sufficiently high for corrosion of the anode to occur and passive film formation on the anode to be avoided when connected to a steel reinforcement, and (e) forming a solid block of the mixture around the anode from (c).
According to yet another aspect of the invention there is provided a method of installing a sacrificial anode to protect the steel reinforcement of reinforced concrete which method comprises in any order: (a) Making an electrical connection between the sacrificial anode and an elongated connector made of a ductile metal capable of being wound around the reinforcement. And, (b) making electrical contact between the elongated connector and the steel reinforcement by winding the elongated connector around the steel reinforcement. In the method (a) may be practiced by casting the anode from a liquid metal in a mold containing part of the connector, to form a block of metal around a portion of the length of the elongated connector. The method may further comprise (carried out before or after (b)) (c) casting around the anode a porous material containing an electrolyte solution having a pH sufficiently high for corrosion of the anode to occur and passive film formation to be avoided. In the method (a) through (c) may be practiced using a zinc anode, and using an electrolyte solution having a pH of at least about 14. The method may also further comprise, after (b), tightening the elongated connector around the reinforcement by twisting the ends of the elongated connector together (e.g. using a ratchet twisting tool).
It is the primary object of the present invention to provide an advantageous assembly and method for cathodic protection of steel and reinforced concrete. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.
ADVANTAGEOUS EFFECT OF THE INVENTION
The connector can be installed in less time than the previously used methods involving the use of self tapping screws and is more secure than the clips or clamps.
REFERENCES:
patent: 5609748 (1997-03-01), Kotowski
patent: 5639358 (1997-06-01), Bennett et al.
patent: 6022469 (2000-02-01), Page
patent: 3434222 (1986-03-01), None
Davison Nigel
Gorrill Christopher D.
Bell Bruce F.
Foseco International Limited
Nixon & Vanderhye P.C.
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