DE69928373T2 - ELECTRICAL CONNECTOR FOR APPLICATION IN CATHODICAL PROTECTION SYSTEMS AND APPLICATION METHOD - Google Patents

Abstract

An assembly for use in the cathodic protection of steel reinforcement in reinforced concrete said assembly comprises: (i) an anode of a metal having a more negative electrode potential than steel and, in electrical contact therewith, (ii) an elongate electrical connector eg a wire made of a ductile metal capable of being wound around the steel reinforcing element to be protected. The anode may be in the form of a block cast around a portion of the length of the elongate connector and preferably the elongate connector comprises a plurality of wires twisted together over a portion of their length with the anode cast around the twisted portion.

Description

scope of application the invention

The The invention relates to a cathodic protection of steel in reinforced concrete, wherein a sacrificial anode is used, in particular the electrical Bond the sacrificial anode with the reinforcing steel it is supposed to protect.

background the invention

sacrificial anodes are well known. To be effective, the sacrificial anode is made of one Metal produced, which has a negative electrode potential than the one to protect Steel so that it corrodes rather than the steel. sacrificial anodes are in the European Patent No. 0707667 and in U.S. Patent No. 5,292,411.

By the Invention to be solved problem

Around to fulfill their purpose, the sacrificial anode must be electrically connected to the steel to be protected. For this Purpose were previously used metal conductors. Previously, these were metal conductors such as wires, at the steel reinforcement fastened by drilling a hole into which a tapping screw was used. Alternative methods included use clips or braces to secure the wire to the one being protected To attach metal.

at There are problems with this method in that drilling of holes and the use of tapping screws are time consuming and there is always a risk that the clips and clips will be removed can be.

The The present invention provides a solution to these problems by Use of a sacrificial anode according to claim 1, a combination of an anode arrangement as defined in claim 9, a method of installing a sacrificial anode as defined in claim 17, and an anode assembly in accordance ready with claim 25. Specific embodiments are claimed in the dependent claims.

advantageous Effect of the invention

The Connector can be installed in less time than at the previously used methods involving the use of self tapping screws included, and is safer than the clips or brackets.

Summary the drawings

1 Figure 4 is a perspective view of an embodiment of the invention in which two wires are twisted together,

2 is a perspective view on a smaller scale than 1 in which the anode has been cast around the wires of the connecting element, and

3 is a perspective view of another embodiment on the same scale as in 2 in which the anode is surrounded by a mortar poured around it.

detailed Description of the invention

The Anode is preferably made of zinc, but also aluminum, Cadmium or magnesium can be used. References to this Metals include the same containing alloys.

Of the electrical contact between the connecting element and the anode is preferably provided by the anode taking the form of a Block of metal, which extends around a portion of the length of the stretched connecting element was poured (with pour mine we are allowed that the liquid metal solidifies to the Block). Alternatively, the electrical contact can thereby be provided that the elongated connecting element to the anode is wound, or that the connecting element to the Anode soldered or to similar ones Fashion is attached to it.

The Stretched connecting element has the form of a practical Wire on, although other elongated shapes can be used. Of the Wire is conveniently made of steel, preferably one soft steel.

Preferably the wire is as noble or noble as the reinforcing steel.

The Connecting element may comprise a plurality of wires, which over a Section of their length twisted together, and the anode can rotate around the rotated section be poured. By the word twisted we mean that it folded over or bent or curled is included. The purpose of the twisted section is to increase the surface area of the wire forming the interface with the cast anode, and thereby improving the electrical contact. The wires can on a position between their ends (for example, near the middle their lengths) be twisted together, leaving lengths of wire on both sides extend the cast anode.

In the patent application no. WO 94/29496 (European Patent Application No. 0707667) describes a method of cathodic protection in which the anode is surrounded by a material containing a high pH electrolyte to maintain cathodic protection over a sustained period of time. To avoid passivation of the anode, it is recommended that the pH in the case of a zinc anode is at least about 14.

at It is suitable materials described in this patent about cementitious mortar, which is poured around the anode to form a unit. It is not essential that the mortar is cementitious is, though such mortar more readily available are. The mortar can be prepared from a cement that has an intrinsically high Has alkali content, wherein the mortar admixed with additional alkali can be, for example, sodium hydroxide or lithium hydroxide, of which the latter is preferred.

at the anode assembly and the connector of the present invention Invention can be porous Material, for example, a cementitious mortar, poured around the anode be. With watering we mean making a solid block out of the liquid or semi-liquid Mortar. The casting is preferably in a mold executed. The porous material is one which is preferably a high pH electrolyte contains as in the European Patent Application No. 0707667, that is, one containing an electrolyte solution a pH sufficiently high to prevent corrosion to maintain the anode, and passive film formation too prevent if the anode is galvanically connected to the steel reinforcement. In the case of a cementitious mortar is the electrolyte solution the pore solution.

Of the mortar preferably has an alkali content of at least 1% Lithium hydroxide based on dry matter for making the mortar used ingredients equivalent is. Conveniently, the amount of lithium hydroxide is greater than 2% or the equivalent Amount of sodium hydroxide of 4%.

lithium hydroxide is the proven Alkali, since lithium ions provide protection against alkaline silica reactions (or alkali aggregates) in concrete provide. Mixtures of alkali can however, for example for Mixtures of lithium hydroxide and sodium hydroxide can be used.

The Anode, the porous one Material, for example mortar, and the casting can be the same as in the European Patent Application No. 0707667.

• (a) Anfertigen einer elektrischen Verbindung zwischen einem gestreckten Verbindungselement und der Anode, und
• (b) Anfertigen eines elektrischen Kontakts mit der Stahlverstärkung durch Wickeln des gestreckten Verbindungselements um die Stahlverstärkung.

According to claim 17 there is provided a method of installing a sacrificial anode to protect the reinforcement from reinforced concrete, the method comprising, inter alia, the following steps (a) and (b) in any order:

• (a) making an electrical connection between a stretched connector and the anode, and
• (b) making electrical contact with the steel reinforcement by winding the stretched fastener around the steel reinforcement.

step (a) can pour the anode by a portion of the length of the elongated connecting element include.

One further step (c) may be carried out before or after step (b), wherein step (c) is pouring a porous one Materials surrounding the anode, which is an electrolyte solution with a pH sufficiently high to cause the occurrence of a Corrosion of the anode and to prevent passive film formation.

Preferably If the anode is made of zinc, the pH of the electrolyte solution in this case is desirably is at least about 14. If the anode is made of another metal such as aluminum the pH may be lower, for example at least 13.3 or 13.5.

The pH can be determined by measuring the hydroxyl ion concentration and applying the equation
pH = 14 + log (OH ^- ) according to Sorensen.

The Invention is applicable to the construction of new reinforced concrete structures, in which the anode arrangement by means of the connecting element and a porous one High pH material such as cast around the anode mortar with the reinforcement connected is.

The Invention is also to the protection of existing concrete structures applicable, wherein in the process a hole is introduced into the concrete, (i) the anode inserted into the hole, (ii) the connector with the reinforcement and (iii) pouring the high pH material around the anode can be. Steps (i), (ii) and (iii) may be in any order be executed.

With reference to 1 In the drawings, two wires, each of which is a soft 16 SWG (Standard Wire Gauge) steel wire, are included over a portion of their length 6 twisted together. The length of the twisted section is typically about 38 to 42 mm. Four lengths of wire in the form of arms 2 . 4 . 8th and 10 extend from the twisted section 6 , The lengths of the arms 2 . 4 . 8th and 10 are typically about 148 to 152 mm, and at the end of each arm there are loops 12 . 13 . 14 and 15 , The arms are each wrapped around the reinforcement. Usually, one or two complete turns are sufficient around the reinforcement to make a satisfactory electrical contact. The diameter of the loops is typically about 9 to 11 mm. The purpose of the loops is to facilitate the use of a tool of the type used to seal paper sacks for potatoes and the like. One suitable tool is a spring-loaded ratchet wheel turning tool known as a Stanley lace-up tool available from Direct Wire Ties Limited. By means of the tool, the arms, which were wound around the steel reinforcement (not shown) in reinforced concrete, can then be twisted together. This will cause the wire to tighten around the reinforcement.

In 2 is a cylindrical zinc block 20 about 40 mm in diameter and about 7 mm thick around the twisted wires. In the figure became the center of the cylindrical block 20 omitted to represent the wires. The top and bottom edges of the block 20 were rounded off to avoid crack initiation.

In the 2 The arrangement shown was made by first twisting the wires near the middle of their length, and then positioning the twisted section in a ceramic casting mold. Then molten zinc was poured into the mold. After solidification of the product, the same was removed from the mold. The wire arms 2 . 4 . 8th and 10 extend on both sides of the anode and allow the anode to be connected to more than one reinforcing element if desired.

In 3 was a mortar block around the in 2 Zinc cast to give a thickness of 10 mm all around the zinc.

In the 3 arrangement shown by positioning the in 2 illustrated arrangement made in a previously vacuum-formed plastic mold to arrange the zinc centrally within the mold. A high-pH cementitious mortar containing a pore solution having a pH greater than 14 was prepared by mixing a Portland cement powder (containing 2% by weight of admixed lithium hydroxide based on the weight of the cement powder) with water, and poured into the mold. The mass was allowed to cure for four hours and then removed from the mold so that the in 3 product obtained was obtained.

Claims (29)

Use of a sacrificial anode to protect a steel reinforcement a reinforced Concrete, wherein the use of the following steps (a) and (b) in any order includes: (a) make an electrical Connection between a sacrificial anode and a stretched connecting element, which comprises a plurality of wires; (B) Make an electrical contact between the stretched Connecting element and the steel reinforcement by winding the stretched Connecting element around the steel reinforcement and twisting each other the wires over one Section of their length, around them for the reinforcement to stretch. Use according to claim 1, wherein the step is a to water the anode of a liquid metal in a mold around a block of metal around a section the length to form the elongated connecting element. Use according to claim 1 or 2, wherein the stretched Connecting element in the form of a wire is. Use according to claim 2, wherein the stretched Connecting element comprises a variety of wires, which over a Section of their length twisted together, and the anode around the rotated section was poured. Use according to claim 4, wherein the wires are connected to one Position between their ends are twisted together, so that the wires extend on both sides of the cast anode. Use according to any one of claims 1 to 5, wherein another Step (c), which is carried out before or after a step (b) can, a pour a porous one Materials surrounding the anode, which is an electrolyte solution with a pH sufficiently high to cause the occurrence of a Corrosion of the anode and to prevent passive film formation. Use according to claim 6, wherein the anode is zinc and the pH of the electrolyte solution is at least about 14. Use according to one of the preceding claims, wherein the elongate connecting element by by twisting the ends of the flexible elongated connecting element below Using a ratchet wheel turning tool is stretched around the reinforcement. Combination of an anode assembly for use in the cathodic protection of a steel reinforcement in reinforced concrete and a steel reinforcement, wherein the combination comprises: (ii) a steel reinforcement for Use in reinforced Concrete; (iii) an anode assembly comprising an anode a metal with a more negative electrode potential than steel and comprising a stretched, electrical, deformable A metal-fabricated fastener comprising a plurality of wires; and wherein the elongated electrical connection element to the steel reinforcement is wound and the wires over one Section of their length twisted together to stretch around the reinforcement, so that the Anode assembly is in electrical contact with the steel reinforcement. Combination according to claim 9, wherein the anode is in is the shape of a block that extends around a portion of the length of the is stretched elongated connecting element. A combination according to claim 9 or 10, wherein the stretched Connecting element in the form of a wire is. A combination according to claim 10, wherein the stretched Connecting element comprises a variety of wires, which over a Section of their length twisted together and the anode around the twisted section was poured. A combination according to claim 12, wherein the wires are connected to a Position between their ends are twisted together, so that the wires extending on both sides of the cast anode. A combination according to any one of claims 9 to 13, wherein another Step (c), which is carried out before or after a step (b) can, a pour a porous one Materials surrounding the anode, which is an electrolyte solution with includes a pH, which is sufficiently high to cause corrosion of the anode and to prevent passive film formation. A combination according to claim 14, wherein the anode is zinc and the pH of the electrolyte solution is at least about 14. A combination according to any one of claims 9 to 15, wherein the stretched Connecting element by twisting together the ends of the flexible ge stretched connecting element using a ratchet wheel turning tool to the reinforcement is curious. Method for installing a sacrificial anode to the steel reinforcement before reinforced To protect concrete the method being the following steps (a) and (b) in any one of Order includes: (a) make an electrical connection between a sacrificial anode and a stretched connecting element, which comprises a plurality of wires; (B) Make an electrical contact between the stretched Connecting element and the steel reinforcement by winding the stretched Connecting element around the steel reinforcement and twisting each other the wires over one Section of their length, around them for the reinforcement to stretch. The method of claim 17, wherein step (a) pour in the anode of a liquid metal in a mold encloses a block of metal around a section the length to form the elongated connecting element. The method of claim 17 or 18, wherein the stretched Connecting element in the form of a wire is. The method of claim 18, wherein the stretched Connecting element comprises a variety of wires, which over a Section of their length twisted together, and the anode around the twisted section was poured. The method of claim 20, wherein the wires are connected to a Position between their ends are twisted together, so that the wires extending on both sides of the cast anode. Method according to one of claims 17 to 21, wherein a further Step (c) performed before or after a step (b) can, a pour a porous one Materials surrounding the anode, which is an electrolyte solution with a pH sufficient to cause corrosion the anode is and to prevent passive film formation. The method of claim 22, wherein the anode is zinc and the pH of the electrolyte solution is at least about 14. A method according to any one of claims 17 to 23, wherein the method for tensioning the wires around the reinforcement twisting the ends of the flexible elongate connecting element together using a ratchet wheel turning tool. An anode assembly for use according to claim 1, wherein the assembly comprises: (i) an anode of a metal having a more negative electrode potential than steel and in electrical contact therewith; (ii) a stretched electrical connector made of deformable metal suitable for winding the steel reinforcing element to be protected , and wherein the anode is in the form of a block which is molded around a portion of the length of the elongate connector, and wherein the elongate connector comprises a plurality of wires twisted together over a portion of their length and the anode around the anode twisted section was poured. Arrangement according to claim 25, wherein the wires over a Position between their ends are twisted together, so that the wires extend on both sides of the cast anode. Arrangement according to claim 25 or 26, wherein the anode in a porous Material is included, which is poured around the anode was, being the porous Material an electrolyte solution whose pH is sufficiently high for the occurrence of a Corrosion of the anode and passive film formation on the anode to prevent when the anode is galvanically connected to the gain. Arrangement according to claim 27, wherein the anode is made of Zinc is made and the porous Material a cementitious mortar that is an electrolyte solution having a pH of at least 14. Arrangement according to one of claims 25 to 28, wherein each Wire at its end has loops to make use of a ratchet wheel turning tool to facilitate.