JP2001011666A - Anode electrode body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a uniform spacing between an electrode and an object to be protected from corrosion and to prevent a direct contact between the electrode and the object to be protected from corrosion by coating a strip-like-shaped electrode with mortar or concrete to form a square bar and providing each end face of the square bar with a connecting piece formed by allowing the end of the electrode to appear. SOLUTION: A strip-like electrode 2 is coated with mortar or concrete 3 into a shape of square bar to form an anode electrode body 1. Either of the following can be used as the strip-like electrode 2: one prepared by weaving fine metal wire into mesh and forming it into strip-like shape; one composed of metal sheet. The length of the anode electrode body 1 is about 1 m and the cross-sectional area of the strip-like electrode 2 is 0.1 m2. The size of the mortar-coated square bar is 2.5 cm in thickness. The end of the electrode 2 is exposed from the end of the square bar to form a connecting piece 4. When the electrode body is provided to a structure, the electrode body is used in a state where the connecting pieces 4 are mutually connected to each other by means of spot welding, etc., to the desired length. As the metal for the electrode 2, it is preferable to use, e.g. titanium having natural potential higher than that of iron in a reinforcing bar as the body to be protected from corrosion and having superior durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode body used for corrosion protection of a steel material such as a reinforcing steel of a steel structure or a concrete structure, and more particularly, to an anode (anode) electrode used in an external power supply type cathodic protection method. Related to the structure.

[0002]

2. Description of the Related Art Since ancient times, humans have used a large amount of iron (Fe) as a metal that exists in large quantities on the earth, is relatively easily refined, has good workability, is inexpensive and is stable. But,
In recent years, corrosion of steel structures in a salt or acidic environment or reinforcing steel in concrete structures has become a social problem. This is because the chemical properties of iron (Fe) used for steel structures and rebars are stable under normal circumstances, with the surface covered with a thin passivation film of iron oxide. This is because the passivation film is destroyed in an environment or in an acidic environment due to environmental pollution or the like, and the oxidation proceeds to the inside, and finally, a situation occurs that leads to the destruction of the structure.

[0003] This has been recognized for a long time, and as a countermeasure, means for preventing corrosion, such as plating a different metal on the surface of iron, have been implemented. There are two types of this means, which are plated with zinc (Zn) or tin (Sn) having different chemical properties (ionization tendency) from iron (Fe).
The former is known as a tin plate, and the latter as a tin plate.
The galvanized sheet has a higher ionization tendency than iron (it is easily corroded)
By plating zinc, it erodes zinc before the iron itself and tries to protect iron from corrosion at the expense of zinc, while the latter tin plate has a lower ionization tendency than iron (less corrosive). The difference is that tin plating covers the iron itself and tries to protect the iron from corrosion.

In recent years, the mechanism of metal corrosion has been elucidated,
Cathodic protection technology has been developed that actively utilizes the inherent chemical properties (natural potential difference) of metals and combines different metals with different chemical properties to electrically prevent corrosion. There are two methods of cathodic protection, a galvanic anode method and an external power supply method. In each case, iron is used as a cathode and a dissimilar metal is used as an anode.

In the galvanic anode method, a sacrificial electrode piece of zinc, aluminum alloy, magnesium alloy, or the like having a higher ionization tendency (lower potential) than iron is used as an anode and is attached to an iron corrosion-protected body, and is used in nature. Immersed in, for example, seawater to form an electric circuit. When this electric circuit is formed, current flows due to the inherent potential difference of metal,
An anode such as zinc, which has a higher ionization tendency than iron, is ionized and eluted, and at the expense of the anode, corrosion of iron, which is an anticorrosion target, is prevented. Although this method has advantages such as easy installation and no special equipment required, it has the disadvantage that it requires periodic replacement of sacrificial anode metal pieces and is difficult to control.

In the external power supply system, it is desirable to use a metal having a lower ionization tendency than iron of the corrosion-protected body, for example, a noble metal such as platinum, but it is expensive, so that a platinum-plated titanium wire, a lead alloy, graphite or the like is used as an anode piece. Used as Then, lead wires are respectively drawn from the corrosion-protected body and the anode piece, connected to a DC power supply, and a corrosion protection current is supplied from the power supply to prevent corrosion of the corrosion-protected body.
The control of anticorrosion can be easily performed by controlling the output voltage of the DC power supply. There is an advantage that the maintenance of the power supply is required, but the replacement of the electrode body is not required.

The present inventor has disclosed a technique in which the anticorrosion technique of the external power supply system is applied to a bridge girder in Japanese Patent Application Laid-Open No. Hei 6-158365. This technique is a technique in which a tension is applied to the electrode wire so that an insoluble electrode wire of a platinum-plated titanium wire is maintained at a constant distance from a steel material as an anticorrosion material as an anode. The reason for this is that when the distance between the electrodes fluctuates, the flowing anticorrosion current becomes non-uniform and the anticorrosion effect is hindered. Conventional electrodes have been used in the form of fine wires, fine wires woven into a mesh, or thin ribbons. These electrodes have low rigidity and are easily deformed, and there is a problem in arranging them at a uniform distance from the anticorrosion target.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an anode which can be easily disposed, can maintain a uniform distance between the object to be protected, and an electrode which is not in direct contact with the electrode to be protected. The purpose is to develop an electrode assembly.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an anode electrode of an external power supply system, which is an electrode made of a thin metal plate or an electrode formed by weaving a thin metal wire in a mesh shape to form a strip-like electrode with mortar or concrete. An anode electrode body characterized in that a square bar is formed, and a connection piece having an exposed end of the electrode is provided on a longitudinal end surface of the square bar. In this case, it is preferable to use titanium as a main component for the electrode.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an anode electrode body 1 according to an embodiment of the present invention. The strip electrode 2 is covered with a mortar 3 in the shape of a square bar. The strip-shaped electrode 2 may be a strip formed by weaving a thin metal wire in a mesh shape, or may be a thin metal plate. From the viewpoint of easy production and easy handling, the length of the anode electrode body 1 is formed to about 1 m. The cross-sectional area of the strip electrode may be, for example, about 0.1 cm ² , and the dimension of the mortar-coated square rod is And a thickness of about 2.5 cm. The connection piece 4 is exposed by exposing the end of the electrode from the end of the square rod.
When arranging the electrode body on the structure, the connecting piece 4
They may be connected to each other by a means such as spot welding and used as a desired length. As the electrode metal, an electrode was used in which a titanium (Ti) fine wire having a higher natural potential than the iron (Fe) of the corrosion-protected body and having high durability was formed in a mesh (grid) shape, but the material is not limited to this. is not. Any electrode metal that can be used may be any material having a higher potential than iron, and nickel, tin, lead, copper, silver, gold, platinum, etc., and alloys and plating materials thereof may be selected in consideration of cost. I just need.

FIG. 2 is a cross-sectional view of the bridge girder 10, showing the arrangement of the anode electrode body when a new girder is manufactured. Bridge girder 10
The anode electrode body 1 is disposed in the concrete near the bottom surface of (1). This is because, when the bridge girder 10 is manufactured, the anode electrode body 1 covered with mortar is connected to a predetermined length on the bottom slab form of the bridge girder 10, and the anode electrode body 1 is used as a spacer. The steel bars 11 and the PC steel material 12 are assembled, a side formwork is erected, and concrete 13 is cast and formed by an ordinary method. Instead of using the anode electrode body 1 as a spacer, the anode electrode body 1 may be fixed to the reinforcing bar 11 with a binding wire, and a separate spacer may be used.

FIG. 3 shows an anode electrode 1 for repairing a concrete girder 10 from which concrete has peeled off due to corrosion of a reinforcing bar.
The example which applied is shown. The concrete 13 of the girder 10 at the peeled portion was peeled off, and the reinforced steel 11 and the PC steel 12 were removed. Further, if necessary, anticorrosion coating is applied, a formwork 14 for embedding an insert 15 in the healthy part of the concrete and restoring to a regular concrete section is attached with a bolt 16, and an aggregate 17 and a filling mortar are filled and repaired. This is an example. In this case, the anode electrode body 1 was embedded for anticorrosion so that the corrosion of the reinforcing bars and the like after the repair did not recur.

FIG. 4 is an explanatory diagram of an external power supply type anticorrosion method using the anode electrode body 1 of the present invention. Lead wires 24 from the anode electrode embedded in the concrete 13 and from the structural reinforcing bar 11 of the concrete girder 10, respectively.
25 is pulled out and connected to a DC power supply 21 installed outside. The lead wire 24 of the electrode of the anode electrode body 1 is connected to the plus (+) terminal 22 of the DC power supply 21, and the lead wire 25 from the reinforcing bar 11 is connected to the minus (−) terminal 23 of the DC power supply 21. By doing so, the anticorrosion current flows from the plus side of the DC power supply 21 to the anode electrode 1 and the reinforcing steel 11
Corrosion is prevented. When a large capacity is required for the DC power supply 21, a commercial AC power supply may be rectified and used.

The above description has been given of the example in which the present invention is applied to a concrete girder. However, the present invention is not limited to the girder, and it is possible to prevent corrosion of reinforcing bars of other concrete structures. Furthermore, the steel member itself is not limited to the concrete structure, and it is also possible to prevent corrosion of the steel member by arranging the anode electrode on the steel member of the steel structure.

[0015]

The anode electrode body of the present invention uses an anode electrode of an external power supply system using titanium having a higher natural potential than a reinforcing bar, and a strip-shaped metal plate or a strip-shaped electrode in which a thin metal wire is woven in a mesh shape. Is covered with mortar or concrete in the shape of a square bar, and the end of the electrode is exposed from the longitudinal end surface of the square bar to form a connection piece.By coating with mortar, the electrode itself can directly contact the reinforcing steel. Therefore, an accurate distance between electrodes can be ensured, a uniform anticorrosion current can be passed, and the anticorrosion target such as a reinforcing bar can be reliably prevented from corroding.

[Brief description of the drawings]

FIG. 1 is a perspective view of an anode electrode body of an embodiment.

FIG. 2 is a sectional view of a bridge girder.

FIG. 3 is an explanatory view of an example applied to repair of a concrete girder from which concrete has separated due to corrosion of a reinforcing bar.

FIG. 4 is an explanatory view of an external power supply-type cathodic protection method using an anode electrode body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode electrode body 2 Electrode 3 Coating body (mortar or concrete) 4 Connection piece 10 Concrete girder (bridge girder) 11 Reinforcing steel 12 PC steel 13 Concrete 14 Formwork 15 Insert 16 Bolt 17 Aggregate 21 DC power supply 22 (+) pole terminal 23 (-) Pole terminal 24, 25 Lead wire

Claims (2)

[Claims] An electrode made of a thin metal plate or an electrode formed by weaving a thin metal wire into a mesh to form a strip is covered with mortar or concrete to form a square bar, and the electrode is formed on the longitudinal end surface of the square bar. An anode electrode body provided with a connection piece whose end is exposed. 2. The anode electrode body according to claim 1, wherein said electrode is mainly composed of titanium (Ti).