JP2020186443A - Corrosion protection structure of iron reinforced concrete structure and corrosion protection method - Google Patents

Abstract

To suppress damage to an iron reinforced concrete structure to minimum by exhibiting an anticorrosion effect by non-contact with a steel bar present inside of the iron reinforced concrete structure, and to reduce installation cost and management cost.SOLUTION: There are provided a conductive member 30 wound around a circumference of an iron reinforcement (main reinforcement 10) present inside of an iron reinforced concrete structure 50, and a power source device 40 supplying an alternate current to the conductive member 30. The conductive member 30 is spirally wound around an iron reinforcement (main reinforcement 10). Further, the iron reinforcement (main reinforcement 10) is divided into a plurality of divisions in an axis direction, and the conductive member 30 may be wound for every division respectively. Furthermore, the conductive member 30 may be wound around an outer periphery part of the iron reinforced concrete structure 50, or may be wound around an outer periphery part of the iron reinforcement (main reinforcement 10) itself. And, an electric current cancelling a corrosion current is generated on a superficial part of the iron reinforcement (main reinforcement 10) by an action of electromagnetic induction to perform the corrosion protection of the iron reinforcement (main reinforcement 10).SELECTED DRAWING: Figure 1

Description

The present invention relates to an anticorrosion technique for a reinforced concrete structure, and more particularly to a structure and a method capable of anticorrosion of a reinforcing bar without damaging the reinforced concrete structure.

The reinforcing bars of the reinforced concrete structure are protected from corrosion because they are placed under strong alkalinity of about pH 12 to 13 by calcium hydroxide produced by the hydration reaction of cement. However, if the concrete is neutralized and the alkalinity is lowered, or if chloride or the like is present in the concrete, the reinforcing bars are easily corroded.

Therefore, in order to prevent corrosion of reinforcing bars in reinforced concrete structures, galvanic anode methods (sacrificial anode methods) and external power supply methods have been proposed. In the current-current anode method, aluminum alloy, zinc alloy, magnesium alloy, etc., which have a higher ionization tendency than iron, are attached to the concrete surface as an anode material, and the anode material and internal reinforcing bars are short-circuited to cause corrosion of the reinforcing bars. This is a technology that cancels out the potential difference of the above by passing a weak DC current from the outside.

The external power supply method is to provide an insoluble electrode and a DC power supply device, connect a positive electrode to the concrete surface and a negative electrode to the reinforcing bar, and let a weak direct current flow directly into the reinforcing bar through the concrete, causing corrosion. It is a technique to cancel the potential difference.

Conventionally, various techniques for preventing corrosion of reinforcing bars due to neutralization or the like have been proposed in reinforced concrete structures (see, for example, Patent Documents 1 and 2).

In the technique described in Patent Document 1, an external DC power source is connected to a reinforced concrete building, the concrete wall surface of the building is set as an anode, and the reinforcing bar is set as a cathode, thereby performing cathode polarization of the reinforcing bar. It is designed to prevent its corrosion. In this technology, the neutralized concrete wall surface or the deteriorated base or coating film is chipped and rusted to the corroded part of iron.

In the technique described in Patent Document 2, an electrode material is attached to the surface of a concrete structure and covered with a chemical sheet, and the reinforcing bars arranged inside the structure are placed on the negative side of the DC power supply. Connect to the positive side and give a negative charge to the reinforcing bar side. The DC power source is such that the DC power source obtained from the photovoltaic power generation panel arranged in the concrete structure is obtained directly or through a secondary battery.

Japanese Unexamined Patent Publication No. 5-195588 JP-A-2002-242448

In all conventional reinforcing bar anticorrosion techniques, including the techniques described in the patent documents described above, the anode material and the reinforcing bar must be connected by a lead wire in order to form an electric circuit inside the reinforced concrete structure, which is physical. It is necessary to ensure continuity. As described above, in the existing electrocorrosion protection method, the anode material and the internal reinforcing bar must be directly connected to the conducting wire or the like, and the concrete is chipped and a part of the reinforcing bar is exposed. Further, since the anticorrosion range depends on the installation range of the anode material, only electrocorrosion protection can be performed at the target site. Furthermore, it is necessary to check the wiring and electrical system for each installation site, which requires time and effort for maintenance.

Since the external power supply method requires the power supply device to be fixed, it is difficult to install it in high places or near coastal ports. Further, in the galvanic anode method, it is necessary to lay a sacrificial anode in the entire reinforced concrete structure, which increases the installation cost. Further, since the performance of the anode material deteriorates over time, it becomes necessary to replace it.

The present invention has been proposed in view of the above circumstances, and by exerting an anticorrosion effect in a non-contact manner with the reinforcing bars existing inside the reinforced concrete structure, damage to the reinforced concrete structure is minimized and the construction cost is reduced. It is an object of the present invention to provide an anticorrosion structure and an anticorrosion method for a reinforced concrete structure capable of reducing management costs.

The anticorrosion structure and the anticorrosion method of the reinforced concrete structure according to the present invention have the following features in order to achieve the above-mentioned object. That is, the anticorrosion structure of the reinforced concrete structure according to the present invention is characterized by including a conductive member wound around the reinforcing bar existing inside the reinforced concrete structure and a power supply device for supplying an alternating current to the conductive member. It is something to do.

In the anticorrosion structure of the reinforced concrete structure described above, the conductive member can be spirally wound around the reinforcing bar existing inside the reinforced concrete structure.

In the anticorrosion structure of the reinforced concrete structure described above, the conductive member can divide the reinforcing bars existing inside the reinforced concrete structure into a plurality of sections in the axial direction and wind each section.

In the anticorrosion structure of the reinforced concrete structure described above, the conductive member can be wound around the outer peripheral portion of the reinforced concrete structure having the reinforcing bar inside, or around the outer peripheral portion of the reinforcing bar itself existing inside the reinforced concrete structure. ..

In the anticorrosion structure of the reinforced concrete structure described above, the reinforcing bar around which the conductive member is wound is the main bar, and the conductive member can be composed of a band bar.

In the method for preventing corrosion of a reinforced concrete structure according to the present invention, a conductive member is wound around a reinforcing bar existing inside the reinforced concrete structure, and an alternating current is supplied to the conductive member. Then, it is characterized in that a current that cancels a corrosion current is generated in the skin portion of the reinforcing bar by the action of electromagnetic induction to prevent corrosion of the reinforcing bar.

According to the anticorrosion structure and the anticorrosion method of the reinforced concrete structure according to the present invention, the anticorrosion structure is formed in non-contact with the reinforcing bars existing inside the reinforced concrete structure. Therefore, the anticorrosion structure can be constructed without damaging the reinforced concrete structure. Moreover, since the anticorrosion structure can be constructed regardless of whether it is an existing structure or a new structure, the range of applicable structures is widened.

As described above, the anticorrosion structure and the anticorrosion method of the reinforced concrete structure according to the present invention can exhibit an excellent anticorrosion effect and reduce the construction cost and the management cost even though they have a simple structure.

The schematic diagram of the anticorrosion structure of the reinforced concrete structure which concerns on embodiment of this invention. An application example (1) of the anticorrosion structure of the reinforced concrete structure according to the embodiment of the present invention. An application example (2) of the anticorrosion structure of the reinforced concrete structure according to the embodiment of the present invention. An application example (3) of the anticorrosion structure of the reinforced concrete structure according to the embodiment of the present invention. The explanatory view of the experimental result of the anticorrosion structure and the anticorrosion method of the reinforced concrete structure which concerns on embodiment of this invention.

Hereinafter, the anticorrosion structure and the anticorrosion method (hereinafter, may be abbreviated as the anticorrosion structure and the anticorrosion method) of the reinforced concrete structure according to the embodiment of the present invention will be described with reference to the drawings. 1 to 5 show an anticorrosion structure and an anticorrosion method for a reinforced concrete structure according to an embodiment of the present invention. FIG. 1 is a schematic view, FIGS. 2 to 4 are application examples, and FIG. 5 is an explanation of experimental results. It is a figure.

<Anti-corrosion structure>
The anticorrosion structure according to the embodiment of the present invention is a technique applicable to both civil engineering structures and building structures, but is suitable for civil engineering structures in which corrosion of reinforcing bars may progress in a particularly severe environment. Can be applied. Further, the reinforced concrete structure to be applied is a column or beam to which a conductive member can be wound, but if the conductive member can be wound, it can also be applied to a diagonal member, a wall or the like.

In the case of an existing reinforced concrete structure, the place where the conductive member is wound is the outer peripheral portion of columns and beams. Further, in the case of a newly installed reinforced concrete structure, a conductive member may be wound around the outer peripheral portion of the reinforcing bar itself in advance, and concrete may be driven into the formwork to create columns and beams.

As shown in FIGS. 1 to 4, the anticorrosion structure according to the embodiment of the present invention includes a conductive member 30 wound around a reinforcing bar (for example, a main bar 10) existing inside the reinforced concrete structure 50, and a conductive member 30. A power supply device 40 that supplies an alternating current to the main component is a main component. The reinforcing bar is a member arranged inside the reinforced concrete structure 50, and includes a main bar 10 and a band bar 20 and the like. In the present embodiment, the main target of anticorrosion is the main muscle 10, but the band muscle 20 can also exert the anticorrosion effect.

<Conductive member>
The conductive member 30 generally uses an electric wire such as a copper wire, but the band 20 around which the main bar 10 is wound may be the conductive member 30. In FIG. 1, the strip 20 and the reinforced concrete structure 50 are not shown. The thickness, conductivity, winding interval, winding position, etc. of the conductive member 30 (electric wire) are appropriately set according to the type, size, installation location, environment, etc. of the reinforced concrete structure 50. Further, the conductive member 30 is preferably coated with a member having insulating properties and corrosion resistance in order to prevent electric leakage, short circuit, corrosion and the like.

<Power supply device>
The power supply device 40 is a device for supplying an alternating current to the conductive member 30, and includes, for example, a high-frequency inverter. The current supplied from the power supply device 40 to the conductive member 30 is for generating a current that cancels the corrosion current in the skin portion of the reinforcing bar by the action of electromagnetic induction, and is a high frequency current in this embodiment. There are various definitions of high frequency, but in this embodiment, it is, for example, about 500 Hz to 2,000 Hz. The frequency of the current supplied from the power supply device 40 is appropriately set according to the type, size, installation location, environment, etc. of the reinforced concrete structure 50. Further, the output of the power supply device 40 may be made variable in accordance with various situations.

<Anti-corrosion method>
In the anticorrosion method according to the embodiment of the present invention, the conductive member 30 is wound around the reinforcing bar (main bar 10) existing inside the reinforced concrete structure 50, and an alternating current is supplied to the conductive member 30. Then, by the action of electromagnetic induction, a current that cancels the corrosion current is generated in the epidermis portion of the reinforcing bar (main bar 10) to prevent corrosion of the reinforcing bar (main bar 10).

<Principle of anticorrosion structure and anticorrosion method>
When the conductive member 30 is spirally wound around the axial direction of the reinforcing bar (main bar 10) and an alternating current is passed, an alternating magnetic field is generated and an eddy current is generated in the reinforcing bar (main bar 10). When an eddy current is generated in the reinforcing bar (main bar 10), the current is canceled by the eddy current in the central portion of the reinforcing bar (main bar 10) due to the skin effect, and the current flows through the skin portion of the reinforcing bar (main bar 10).

Then, the corrosion current can be canceled out by the current flowing due to the skin effect to prevent corrosion. Since the skin effect is an effect that is remarkably generated by a high frequency current, it is considered that the current flowing through the conductive member 30 is preferably a frequency of about 1,000 Hz to 2,000 Hz.

<Application example (1)>
Hereinafter, application examples of the anticorrosion structure and the anticorrosion method according to the present invention will be described. The first application example is a mode in which the conductive member 30 is wound around the outer peripheral portion of a column or a beam. In the first application example, as shown in FIG. 2, the conductive member 30 is spirally wound around the outer peripheral portion of the column or beam which is the reinforced concrete structure 50.

In the first application example, the conductive member 30 is spirally wound around almost the entire axial direction of the main bar 10. With such a configuration, the reinforced concrete structure 50 does not need to be suspended or embedded with a power source, and the reinforced concrete structure 50 is not damaged.

The first application example can be suitably applied to the existing reinforced concrete structure 50. That is, the conductive member 30 is spirally wound around the outer peripheral portion of the column or beam of the reinforced concrete structure 50 in which the corrosion of the reinforcing bar (main bar 10) is a concern, and the alternating current is supplied from the power supply device 40 to the conductive member 30. , A current that cancels the corrosion current is generated in the skin portion of the reinforcing bar (main bar 10), and the anticorrosion effect can be exhibited.

<Application example (2)>
In the second application example, as shown in FIG. 3, the conductive member 30 is spirally wound around the outer peripheral portion of the reinforcing bar (main bar 10) itself existing inside the column or beam which is the reinforced concrete structure 50. The second application example can be suitably applied to the newly constructed reinforced concrete structure 50.

That is, when constructing the reinforced concrete structure 50 in which the reinforcing bar (main bar 10) is concerned about corrosion, the conductive member 30 is spirally wound around the outer peripheral portion of the main bar 10 of the column or beam, and both ends of the conductive member 30 are columns. Pillars and beams are formed by driving concrete into the formwork while projecting to the outside of the columns and beams. Then, by supplying an alternating current from the power supply device 40 to the conductive member 30, a current that cancels the corrosion current is generated in the skin portion of the reinforcing bar (main bar 10), and the anticorrosion effect can be exhibited.

In the second application example, the conductive member 30 is wound around the outer peripheral portion of the reinforcing bar (main bar 10) in advance, and both ends of the conductive member 30 are projected to the outside of the column or beam, so that the reinforced concrete structure 50 is used. There is no need for fishing work or embedding of a power source, and the reinforced concrete structure 50 is not damaged.

<Application example (3)>
In the third application example, as shown in FIG. 4, the reinforcing bars (main bars 10) existing in the reinforced concrete structure 50 are divided into a plurality of sections in the axial direction, and the conductive member 30 is wound around each section. .. For example, the columns and beams are divided into upper and lower halves with respect to the axial direction of the main bar 10, and the conductive member 30 is wound around each section. By supplying an alternating current from the power supply device 40 to the conductive member 30 in each section around which the conductive member 30 is wound, a current for canceling the corrosion current is generated in the skin portion of the reinforcing bar (main bar 10) to exert an anticorrosion effect. can do.

Almost no current that cancels the corrosion current is generated in the place where the conductive member 30 is not wound, but the current that cancels the corrosion current generated in the section around which the conductive member 30 is wound prevents corrosion even in the place where the conductive member 30 is not wound. The effect can be expected.

The number of sections, the range around which the conductive member 30 is wound, and the like may be set according to various conditions such as the shape of the reinforced concrete structure 50 and the installation location.

<Experimental results>
Experiments were conducted on the anticorrosion structure and the anticorrosion method according to the present invention. The experiment was carried out under various conditions. That is, in the experimental device, the vinyl chloride pipe (PVC pipe) is regarded as the outer peripheral portion of the reinforced concrete structure 50, and the reinforcing bars (main bar 10, band bar 20) are arranged inside the PVC pipe, and the reinforcing bar (main bar 10, band bar 20) is arranged on the outer peripheral portion of the PVC pipe. A copper wire is wound in a spiral shape, and when salt water is sprayed on the reinforcing bars (main bar 10, band bar 20) and no current of a predetermined frequency is passed through the copper wire (without corrosion protection), the predetermined frequency is applied to the copper wire. The corrosion rate of the reinforcing bars (main bar 10, band bar 20) was measured when the current was applied (with corrosion protection).

FIG. 5 (a) is an experimental result of "without anticorrosion", and FIG. 5 (b) is an experimental result of "with anticorrosion". In this experiment, the corrosion rate was calculated based on the mass before the experiment and the mass after the experiment. The frequency of the current was 500 Hz, and the current value was 10.5 A.

As shown in FIG. 5A, the corrosion rate of the main bar was 1.695 to 4.782% and the corrosion rate of the band bar was 8.567% in the case of "without anticorrosion". Further, as shown in FIG. 5B, in the case of "with corrosion protection", the corrosion rate of the main bar was 0.080 to 0.163%, and the corrosion rate of the band bar was 0.362%.

As is clear from the above-mentioned experiment, according to the anticorrosion structure and the anticorrosion method according to the present invention, a remarkable anticorrosion effect was observed not only on the main muscle 10 but also on the band muscle 20.

10 Main bar 20 Band bar 30 Conductive member 40 Power supply device 50 Reinforced concrete structure

Claims (7)

Conductive members wrapped around the reinforcing bars existing inside the reinforced concrete structure,
A power supply device that supplies alternating current to the conductive member,
With,
Anticorrosion structure of reinforced concrete structure characterized by this. The conductive member is spirally wound around a reinforcing bar existing inside a reinforced concrete structure.
The anticorrosion structure of the reinforced concrete structure according to claim 1, wherein the structure is characterized by the above. In the conductive member, the reinforcing bars existing inside the reinforced concrete structure are divided into a plurality of sections in the axial direction, and the reinforcing bars are wound around each section.
The anticorrosion structure of the reinforced concrete structure according to claim 1 or 2, wherein the structure is characterized by the above. The anticorrosion structure of a reinforced concrete structure according to any one of claims 1 to 3, wherein the conductive member is wound around an outer peripheral portion of a reinforced concrete structure having reinforcing bars inside. The anticorrosion structure of a reinforced concrete structure according to any one of claims 1 to 3, wherein the conductive member is wound around an outer peripheral portion of the reinforcing bar itself existing inside the reinforced concrete structure. The reinforcing bar around which the conductive member is wound is the main reinforcing bar.
The conductive member is made of a strip.
The anticorrosion structure of the reinforced concrete structure according to claim 5, characterized in that. A conductive member is wrapped around the reinforcing bars existing inside the reinforced concrete structure.
An alternating current is supplied to the conductive member to supply it.
By the action of electromagnetic induction, a current that cancels the corrosion current is generated in the skin portion of the reinforcing bar to prevent corrosion of the reinforcing bar.
A method of preventing corrosion of reinforced concrete structures, which is characterized by this.

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