JP2020064037A - Corrosion sensor and method for detecting corrosion - Google Patents

Abstract

To provide a corrosion sensor capable of measuring a corrosion state of a steel material in a concrete structure in a short time and monitoring it for a long time.SOLUTION: A corrosion sensor 10 for detecting a corrosion state of a steel material in a concrete structure 1 includes: an electric wire 3a electrically connected with the steel material; an electrode 30 arranged on a surface of the concrete structure; and a voltage detecting unit 60 for detecting a voltage between the electrode and the electric wire. The electrode includes a hot melt electrode 50 containing hot melt resin in which conductive filler is dispersed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a corrosion sensor that detects a corrosion state of a steel material in a concrete structure, and a corrosion detection method.

  A self-potential measuring method is known as a method for determining corrosion of steel materials such as reinforcing bars of concrete structures. The self-potential measuring method is a method of electrochemically determining corrosion of steel by measuring the potential of steel that changes due to corrosion.

  A sensor using the self-potential measuring method usually needs to measure the concrete surface after it is in a wet state (for example, Patent Documents 1 and 2). However, since the measured value changes depending on the wetness of concrete, there is a problem in stability of the measured value, and there is a problem that it takes time for stabilization. In addition, it is not suitable for long-term monitoring of corrosion conditions because it requires preparations each time.

  Patent Document 3 discloses a collation electrode including an electrode plate provided with an adhesive portion made of a conductive adhesive, and as the adhesive, a high-molecular polymer to which an electrolyte is added as an additive is disclosed. Listed.

  In addition, the present inventors disclose in Patent Document 4 a corrosion sensor including a contact member containing an ionic liquid between the surface of a concrete structure and a reference electrode. Patent Document 4 discloses that the ionic liquid is mixed with a high molecular weight polymer to form a gel. According to the method of Patent Document 4, it is said that ionic liquid can realize stable contact with high electric conductivity for a long period of time.

JP, 2013-181778, A JP, 9-5286, A Patent No. 6018467 JP, 2008-9819, A

The pressure-sensitive adhesive of Patent Document 3 is basically used by containing water, and there is a problem that the measured value changes depending on the degree of drying of the pressure-sensitive adhesive. Therefore, the swelling may reduce the adhesiveness, which is not suitable for long-term monitoring of the corrosion state.
Further, in the contact member containing the ionic liquid of Patent Document 4, deterioration of the ionic liquid, permeation into concrete, and the like were observed to reduce electric conductivity.
As described above, there is a demand for a corrosion sensor capable of stable voltage measurement for a longer period of time.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a corrosion sensor and a corrosion detection method capable of long-term monitoring.

The corrosion sensor of this implementation is
A corrosion sensor for detecting a corrosion state of a steel material in a concrete structure,
An electric wire electrically connected to the steel material,
An electrode arranged on the surface of the concrete structure,
A voltage detection unit for detecting a voltage between the electrode and the electric wire,
The electrode has a hot melt electrode containing a hot melt resin in which a conductive filler is dispersed.

  In one embodiment of the above corrosion sensor, the conductive filler is silver or conductive carbon.

  In one embodiment of the above corrosion sensor, the hot melt resin includes a thermoplastic elastomer.

  In one embodiment of the above corrosion sensor, the electrode further has a reference electrode on the hot melt electrode.

  One embodiment of the corrosion sensor further includes a base material on the electrode.

  One embodiment of the corrosion sensor includes a plurality of the electrodes, and the plurality of electrodes are arranged in a pattern on a sheet-shaped base material.

  One embodiment of the corrosion sensor further includes a wireless transmission unit that wirelessly transmits information based on the detected voltage.

  In one embodiment of the corrosion sensor, the wireless transmission unit further includes a battery that supplies electric power.

  In one embodiment of the corrosion sensor, the front electrode and the voltage detection unit are connected by a detection pattern, and at least a part of the detection pattern is a pattern wiring formed on at least one surface of the base material. .

The corrosion detection method of this implementation is
A corrosion detection method for detecting a corrosion state of a steel material in a concrete structure,
A preparatory step of preparing the corrosion sensor according to the present invention,
An electric wire provided in the corrosion sensor, an electric wire connecting step of electrically connecting with the steel material,
An adhesion step of adhering the electrode provided in the corrosion sensor to the surface of the concrete structure,
A voltage detecting step of detecting a voltage between the electrode and the steel material,
The adhering step includes a step of heating and melting the hot melt electrode.

One embodiment of the above corrosion detection method is
The preparation step is a preparation step of preparing a corrosion sensor including a wireless transmission unit,
After the voltage detection step, the method further includes the step of wirelessly transmitting information based on the detected voltage.

  According to the present invention, it is possible to provide a corrosion sensor and a corrosion detection method capable of long-term monitoring.

It is a figure which shows the installation state of the corrosion sensor in 1st Embodiment. It is sectional drawing of the principal part of the corrosion sensor in 1st Embodiment. It is an enlarged view of the III section of FIG. It is sectional drawing of the principal part of the corrosion sensor in 2nd Embodiment. It is sectional drawing of the principal part of the corrosion sensor in 3rd Embodiment. It is a schematic diagram of the corrosion sensor in a 3rd embodiment. It is an enlarged view of the VII section of FIG. It is sectional drawing of the electrode of the corrosion sensor in 4th Embodiment. It is a schematic front view of the electrode sheet provided with a wiring pattern in the fifth embodiment. FIG. 9B is a side view of FIG. 9A. 3 is a flowchart of an embodiment of a corrosion detection method.

[Corrosion sensor]
The corrosion sensor of this implementation is
A corrosion sensor for detecting a corrosion state of a steel material in a concrete structure,
An electric wire electrically connected to the steel material,
An electrode arranged on the surface of the concrete structure,
A voltage detection unit for detecting a voltage between the electrode and the steel material,
The electrode has a hot melt electrode containing a hot melt resin in which a conductive filler is dispersed.

The corrosion sensor of this embodiment can be a corrosion sensor capable of long-term (for example, 3 months or more) monitoring with the above-described configuration.
Regarding such a corrosion sensor of the present embodiment, the electrodes will be described first, and then each embodiment will be described with reference to the drawings.

<Electrode>
The electrode used in the corrosion sensor of the present embodiment has at least a hot-melt electrode containing a hot-melt resin in which a conductive filler is dispersed, and if necessary, further has another structure such as a reference electrode. It's okay. Each configuration of such an electrode will be described below.

(Hot melt electrode)
In the present embodiment, the hot melt electrode is arranged and used on the surface of the concrete structure.
In the present embodiment, the hot melt electrode is one that is melted by heating, attached to the surface of the concrete structure, and then cooled and solidified. Therefore, the concrete structure is firmly held in close contact with the surface. Further, since the hot melt electrode fills the voids on the surface of the concrete structure, the contact resistance is suppressed. Further, since the conductive filler is dispersed in the hot melt resin, it is retained in the electrode without being dissociated from the electrode and penetrating into the concrete structure.
Therefore, the hot melt electrode of the present embodiment has a small state change on the surface of the concrete structure, and can stably measure the voltage. Thus, by using the electrode, a corrosion sensor capable of long-term monitoring can be obtained.

  The hot melt electrode of the present embodiment contains at least a hot melt resin and a conductive filler, and may further contain other components, if necessary. Hereinafter, each component contained in such a hot melt electrode will be described.

(1) Hot-melt resin In the present embodiment, the hot-melt resin contains a resin that can be heated and melted when the electrode is installed on the surface of the concrete structure, and a thermoplastic resin can be used as such a resin. .

  Examples of the thermoplastic resin include polyurethane resin, acrylonitrile resin, acrylic resin, polyamide resin, polyvinyl butyral resin, polyester resin, styrene resin, silicone resin, and thermoplastic elastomer. They may be used alone or in combination of two or more.

  In the present embodiment, the hot melt resin preferably contains a thermoplastic elastomer. By including the thermoplastic elastomer, the electrode having rubber elasticity at room temperature (for example, 25 ° C.) can be obtained. By having the rubber elasticity, the corrosion of the electrode can be suppressed, and the corrosion sensor that can be monitored for a longer period can be obtained. The elastic modulus of the thermoplastic elastomer at room temperature may be, for example, 0.1 to 100 MPa.

Examples of the thermoplastic elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene. -Styrene-based thermoplastic elastomer such as ethylene / propylene-styrene block copolymer (SEPS); urethane-based thermoplastic elastomer (TPU); olefin-based thermoplastic elastomer (TPO); polyester-based thermoplastic elastomer (TPEE); polyamide-based Examples thereof include thermoplastic elastomers, fluorine-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, and the like, and they can be used alone or in combination of two or more. Further, the thermoplastic elastomer may be hydrogenated.
In the present embodiment, it is preferable to include a styrene-based thermoplastic elastomer among the thermoplastic elastomers.

In the present embodiment, the weight average molecular weight of the hot melt resin is preferably 5,000 or more and 1,000,000 or less, more preferably 10,000 or more and 800,000 or less, from the viewpoint of handleability.
In the present embodiment, the weight average molecular weight is a polystyrene-equivalent molecular weight measured by GPC (gel permeation chromatography) "HLC-8320" manufactured by Tosoh Corporation.

  From the viewpoint of conductivity and adhesiveness, the content of the hot-melt resin is preferably 40 to 98% by mass, and more preferably 60 to 95% by mass in 100% by mass of the total amount of the hot-melt electrode.

(2) Conductive Filler In the present embodiment, the conductive filler is used by being dispersed in the hot melt resin to ensure the conductivity of the electrode. The conductive filler can be appropriately selected from known ones. The shape of the conductive filler may be any particle shape that can be dispersed in the hot melt resin, and may be any shape such as flake shape (scaly shape), spherical shape, needle shape, fibrous shape, or dendritic shape. From the viewpoint of ensuring the conductivity while reducing the content ratio of the conductive filler, it is preferable to use the flaky conductive filler.

  Examples of the material of the conductive filler include metals such as silver, gold, copper, zinc, zinc oxide, manganese, nickel, and aluminum; tin oxide-doped indium oxide (ITO), tin oxide-doped indium oxide (FTO), tin oxide (IO). ), Metal oxides such as neodymium / barium / indium oxides; organic substances such as polypyrrole-based, polythiophene-based, polyaniline-based, oligothiophene-based; carbon black, graphite, graphene, graphite, carbon nanotubes, carbon fibers, fullerene, graphene oxide In addition to conductive carbon such as acetylene black, inorganic insulators such as alumina and glass and polymers such as polyethylene and polystyrene whose surface is coated with a conductive material can be used. In the present embodiment, the conductive filler may be used alone or in combination of two or more.

In the present embodiment, among them, the conductive filler is preferably silver or conductive carbon, and more preferably conductive carbon. Further, as the conductive carbon, graphite, carbon fiber, carbon black, carbon nanotube, graphene, or graphene oxide is particularly preferable.
Since silver and conductive carbon have excellent conductivity and various resistances such as heat resistance, water resistance, and acid resistance, the electrode has excellent long-term reliability. In addition, the hot-melt electrode using silver or conductive carbon has a stable presence of the silver or conductive carbon, and long-term monitoring is possible, so it is possible to capture voltage changes without using a reference electrode. You can Therefore, the corrosion sensor can be realized even if the electrode of this embodiment does not have a reference electrode.

From the viewpoint of conductivity and adhesiveness, the content ratio of the conductive filler is preferably 2 to 60 mass% and more preferably 5 to 40 mass% in 100 mass% of the hot melt electrode.
The thickness of the hot melt electrode is not particularly limited, but is, for example, 50 to 2000 μm, preferably 100 to 1500 μm.

(3) Other components The hot melt electrode of the present embodiment may contain other components as long as the effect is not impaired. Suitable other ingredients include tackifiers, plasticizers and the like. Since the hot melt electrode containing the tackifier or the plasticizer is provided with the tackiness, it can be temporarily fixed to the concrete surface and the construction at the time of adhesion becomes easy. The tackifier and the plasticizer may be appropriately selected from known ones and used alone or in combination of two or more kinds. Moreover, the tackifier and the plasticizer may be used alone or in combination.
When the hot-melt electrode contains a tackifier or a plasticizer, the total content ratio thereof is preferably 0.5% by mass or more and 40% by mass or less, and 1% by mass or more and 20% by mass, in 100% by mass of the total amount of the hot-melt electrode. % Or less is more preferable.

  Further, the hot melt electrode of the present embodiment, as other components, for example, silane coupling agent, titanate coupling agent, flexibility imparting agent, flame retardant, storage stabilizer, antioxidant, metal deactivating agent. Agents, ultraviolet absorbers, thixotropy imparting agents, leveling agents, defoaming agents, dispersion stabilizers, fluidity imparting agents, defoaming agents, antiblocking agents, flame retardants, coloring materials and the like. When the hot melt electrode contains these components, the content ratio thereof is preferably 5% by mass or less and more preferably 3% by mass or less in 100% by mass of the total amount of the hot melt electrode.

(Other configurations)
In the present embodiment, the electrode may have a configuration having only the hot melt electrode, or may have another configuration such as a reference electrode, if necessary.

  The reference electrode is provided on the surface of the hot melt electrode opposite to the surface arranged on the surface of the concrete structure. In the present embodiment, the reference electrode can be appropriately selected and used from known reference electrodes used in the spontaneous potential measurement method. Examples thereof include a silver / silver chloride electrode and a silver / silver chloride electrode containing carbon flakes.

Moreover, you may have a base material further on an electrode. The base material is usually arranged on the surface of the hot melt electrode opposite to the surface arranged on the surface of the concrete structure. When the reference electrode is provided, the base material is arranged on the reference electrode. The base material not only improves handleability at the time of manufacturing the electrode, but also has a function as a protective film for the hot melt electrode when the electrode is used.
In the present embodiment, the substrate is not limited, and can be appropriately selected from various resin films, for example. Examples of the material of the base material include polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, polyether sulfone, polyethylene naphthalate, polybutylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, cycloolefin polymer, ABS ( Acrylonitrile-butadiene-styrene copolymer resin), AES (acrylonitrile-ethylene-styrene copolymer resin), Kaidak (acrylic modified vinyl chloride resin), modified polyphenylene ether, and films such as polymer alloys composed of two or more of these resins, These laminated films etc. are mentioned. The substrate may be transparent or opaque. The base material preferably has flexibility because it easily follows the irregularities on the concrete surface.

(Method of manufacturing electrode)
An example of the method of manufacturing the electrode in this embodiment will be described below.
As an example of a method for manufacturing an electrode, first, the hot melt resin, the conductive filler, and other components used as necessary are mixed to form a mixture. The mixture may contain a solvent that dissolves the hot melt resin in order to disperse it uniformly.
Then, the mixture is dispersed by a known disperser to obtain a dispersion. Examples of the disperser include roll mills such as two rolls and three rolls, ball mills such as ball mills and vibrating ball mills, paint conditioners, bead mills such as continuous disc type bead mills and continuous annular bead mills.
Then, the obtained dispersion is applied onto a substrate. The coating method may be appropriately selected depending on the thickness and material of the hot melt electrode. For example, inkjet method, spray method, spin coating method, dip method, roll coating method, blade coating method, doctor roll method, doctor blade method, curtain coating method, slit coating method, screen printing method, reversal printing method, hot melt applicator , Hot melt coater, slit coater, hot melt roll coater and the like. A hot melt electrode can be obtained by drying the obtained film as needed.
When the base material is unnecessary, the base material may be peeled off after forming a coating film similar to the above using a peelable base material. When the electrode has a reference electrode, the reference electrode may be formed on the base material and then the dispersion for the hot melt electrode may be applied to the reference electrode to form the hot melt electrode.

<First Embodiment>
A first embodiment of the corrosion sensor will be described with reference to FIGS. 1 to 3. In addition, in the present embodiment, an example of detecting corrosion of a concrete structure having a reinforcing bar as a steel material will be described.

As shown in FIG. 1, the corrosion detection system 5 includes a corrosion sensor 10 and a processing unit 90.
The corrosion sensor 10 includes an electrode 30 and a voltage detection unit 60, and detects the corrosion state of the concrete structure 1 having the reinforcing bars 2. In the present embodiment, as shown in FIG. 1, a plurality of corrosion sensors 10 are provided corresponding to each region of the inner wall surface of the tunnel which is the surface 1a of the concrete structure 1.
Each corrosion sensor 10 has a plurality of electrodes 30.
In this embodiment, at least each of the electrodes 30 is installed in the tunnel, and corrosion of the inner wall surface of the tunnel is detected.

  As shown in FIG. 2 described later, the corrosion sensor 10 further includes an electric wire 3a. The electric wire 3a is electrically connected to the reinforcing bar 2. Specifically, a part of the reinforcing bar 2 is exposed from the concrete structure 1 and the exposed reinforcing bar 2 and the electric wire 3a are connected. As a simple means for connecting the electric wire 3 a to the reinforcing bar 2, the electric wire 3 a may be directly wound around the exposed reinforcing bar 2 to form the contact 20. As another means for connecting the electric wire 3a to the reinforcing bar 2, the contact 20 may be formed by a conductive clip or hook and connected to the reinforcing bar 2, or the contact 20 may be formed by welding or screwing. It may be connected to the reinforcing bar 2.

The drawing shown in the lower part of FIG. 1 shows a part of the plurality of electrodes 30 installed in the tunnel in an enlarged manner. As shown in the enlarged view, the plurality of electrodes 30 are planarly arranged on the surface 1 a of the concrete structure 1 along the reinforcing bars 2. In this embodiment, the plurality of electrodes 30 are arranged over a wide area of the surface 1 a of the concrete structure 1.
Therefore, the corrosion sensor 10 detects the voltage at each point on the surface 1a of the concrete structure 1 where the electrode 30 is installed in the voltage detection unit 60 which will be described later in detail.

The voltage detection unit 60 and the processing unit 90 are communicably connected to each other, and information based on the detected voltage at each point is output from the voltage detection unit 60 of the corrosion sensor 10 to the processing unit 90.
The information based on the voltage at each point sent from the voltage detection unit 60 is output by display, printing, etc. in the processing unit 90 and presented to the operator. The processing unit 90 may output the voltage at each point as it is, but if it outputs it as the potential of the plate surface 40b of the verification electrode 40 with respect to the electric wire 3a, it becomes possible to detect corrosion as a natural potential. Further, the processing unit 90 may output map data as shown below.
Further, by correlating the natural potential and the corrosion level, it is possible to output the corrosion level as map data instead of the natural potential.

In the processing unit 90, the relationship between each point where the electrode 30 is installed and the position of each point is stored in advance as data. The processing unit 90 associates the information based on the detected voltage of each point and the position of the surface 1a of the concrete structure 1 from the stored relationship.
Therefore, the processing unit 90 associates the information based on the detected voltage of each point with the position of the surface 1a of the concrete structure 1 to obtain map data of the natural potential and the corrosion level of the surface 1a of the concrete structure 1. Can be created.
The created map data is output by the processing unit 90 by display, printing, etc., and presented to the operator. The map data presented to the operator shows the relationship between the spontaneous potential and the position or the relationship between the corrosion level and the position by contour lines or a color map.
By showing the relationship between the spontaneous potential and the position or the relationship between the corrosion level and the position by contour lines or a color map, the operator evaluates the two-dimensional distribution of the natural potential or the corrosion level along the surface 1a of the concrete structure 1. can do.
In the present embodiment, the operator determines the corroded portion of the reinforcing bar 2 from the map data, reports the corrosion state, or repairs or maintains the corroded portion.
The processing unit 90 used in this embodiment may be any computer system having a CPU, a storage unit, an I / O unit, etc., but may be an electric circuit or an electronic circuit. A portable terminal such as a notebook computer, PDA, or tablet may be used as the processing unit 90 so that the information based on the voltage detected at any place can be confirmed.

The structure of the corrosion sensor 10 of this embodiment will be described.
FIG. 2 shows each electrode 30 as viewed from a cross section along the reinforcing bar 2 which is perpendicular to the surface 1 a of the concrete structure 1.
Each electrode 30 includes a reference electrode 40 and a hot melt electrode 50.
In the present embodiment, the electric wire 3 a connected to the reinforcing bar 2 via the contact 20 is electrically connected to the voltage detection unit 60.
The contact member 50 of the electrode 30 is arranged so as to face the surface 1a of the concrete structure 1 and is in contact with the surface 1a of the concrete structure 1.

In FIG. 3, one electrode 30 of the plurality of electrodes 30 is shown in detail. It should be noted that the electrodes 30 shown in the drawings are all laminated bodies in which the reference electrode 40 and the base material 70 are laminated in this order on the hot melt electrode 50. However, the configuration of the electrode 30 is at least the hot melt electrode as described above. The electrode 50 may be provided.
When the reference electrode 40 has the matching electrode 40, the reference electrode 40 has a plate shape having a pair of plate surfaces 40a and 40b.
The verification electrode 40 is installed so that the plate surface 40a faces the surface 1a of the concrete structure 1. The plate surface 40b of the verification electrode 40 is electrically connected to the voltage detection unit 60 by the detection pattern 3b.

  The hot melt electrode 50 is arranged so as to be interposed between the plate surface 40a of the verification electrode 40 and the surface 1a of the concrete structure 1, and good electrical contact between the verification electrode 40 and the surface 1a of the concrete structure 1 is achieved. To maintain. In the present embodiment, the hot melt electrode 50 has a pair of surfaces at least when installed on the concrete structure 1, one surface is in contact with the surface 1a of the concrete structure 1, and the other surface is a plate. It is in contact with the surface 40a to the detection pattern 3b.

The corrosion sensor 10 may further include a plurality of base materials 70. On one surface of each base material 70, a pair of a verification electrode 40 and a hot melt electrode 50, which are provided as needed, are laminated.
The plate surface 40b of the verification electrode 40, or the hot melt electrode 50 and the detection pattern 3b are electrically connected to each other through the through hole of the base material 70.

  The voltage detection unit 60 detects the voltage between the connected electric wire 3a and the reference electrode 40 or the hot melt electrode 50 as a natural potential. The voltage may be detected all the time or only when necessary.

  Each electrode 30 is fixed by adhering to the surface 1a of the concrete structure 1 while heating and melting the hot melt electrode 50 and cooling it.

  In the present embodiment, since the hot melt electrode 50 is used as the electrode 30, even if the surface 1a of the concrete structure 1 has irregularities, the hot melt electrode 50 is deformed along the irregularities during melting, and further, It is possible to fill minute voids in the concrete structure 1. As a result, good electrical contact is maintained with respect to the surface 1a of the concrete structure 1.

When the contact member is made of a gel using a solvent such as alcohol or water, the alcohol or water evaporates. Therefore, it was necessary to go to the detection site each time to detect the electric contact.
In the present embodiment, since the hot melt electrode 50 containing the hot melt resin in which the conductive filler is dispersed is used, it is less likely to deteriorate with time as compared with the gel in which the solvent is evaporated. Therefore, it becomes possible to maintain highly conductive electrical contact for a long period of time, and it is not necessary to go to the detection site for each detection. Therefore, it is possible to always detect remotely.

Further, immediately after the surface 1a of the concrete structure 1 is in a wet state, it takes time for the potential to settle down. In addition, the wet state changes every time the wet state is set, and the measured potential changes depending on the degree of the wet state. Therefore, it is necessary to repeat the measurement many times in order to obtain a stable measurement result.
Since each electrode 30 of the present embodiment always maintains highly conductive electrical contact with the surface 1a of the concrete structure 1, it is not necessary to wait until the potential settles down, and the time for re-measurement can be reduced. Therefore, the measurement time can be shortened.

<Second Embodiment>
A second embodiment of the corrosion sensor will be described with reference to FIG.
The corrosion sensor 110 of the present embodiment is basically the same as that of the first embodiment, but the structure of the base material is different.

As shown in FIG. 4, the corrosion detection system 105 includes a corrosion sensor 110 and a processing unit 90.
The corrosion sensor 110 of this embodiment includes a base material 170.
As shown in FIG. 4, the base material 170 has a plurality of electrodes 30, and the plurality of electrodes 30 are arranged in a pattern on the sheet-shaped base material 170. Each electrode 30 comprises a pair of stacked reference electrode 40 and hot melt electrode 50.
In the present embodiment, the base material 170 has flexibility.

Each electrode 30 is fixed to the surface 1a of the concrete structure 1.
Specifically, the hot melt electrodes 50 of the arrayed electrodes 30 are heated and melted and adhered to the surface 1 a of the concrete structure 1.

Further actions and effects of the corrosion sensor 110 of this embodiment will be described.
In the present embodiment, since the base material 170 has flexibility, for example, when the corrosion sensor 110 is installed on the inner wall surface of the tunnel, when the base material 170 is fixed to the inner wall of the tunnel, the curved surface of the inner wall of the tunnel or The base material 170 is deformed along the uneven surface. Therefore, a plurality of electrodes 30 can be installed along the curved surface or uneven surface of the inner wall of the tunnel.

<Third Embodiment>
A third embodiment of the corrosion sensor will be described with reference to FIGS.
The corrosion sensor 210 of this embodiment is basically the same as that of the second embodiment, except that it is equipped with a wireless transmission unit.

As shown in FIG. 5, the corrosion detection system 205 includes a corrosion sensor 210 and a processing unit 290.
The corrosion sensor 210 includes an electric wire 203a, a plurality of electrodes 30 including a matching electrode 40 and a hot melt electrode 50, and a plurality of voltage detection units 80. In the present embodiment, as shown in FIG. 5, a corresponding voltage detection unit 80 is arranged next to each electrode 30.

The corrosion sensor 210 includes a base material 270.
In the present embodiment, the base material 270 is made of a flexible sheet.
As shown in FIG. 6, a plurality of pairs of one electrode 30 and one voltage detection unit 80 are provided on the surface 270 a of the base material 270 so as to be arranged in a grid pattern over the entire base material 270.

The corrosion sensor 210 is fixed to the concrete structure 1 with an adhesive.
As a modified example, the base material 270 is formed of a thin sheet, and the base material 270 is fixed to the surface 1a of the concrete structure 1 with pins, staples, or the like at a position avoiding the electrode 30 and the voltage detection unit 80, thereby causing corrosion. The sensor 210 may be fixed to the concrete structure 1.

The base material 270 includes a conductive main pattern 203D that gives a uniform electric potential over the entire base material 270.
In the present embodiment, the main pattern 203D is provided as an intermediate layer of the base material 270, but it may be provided on the front surface 270a of the base material 270 or on the back surface 270b of the base material.
The electric wire 203a electrically connected to the reinforcing bar 2 is electrically connected to the main pattern 203D.
The main pattern 203D may be a surface pattern or a line pattern, and may be any pattern as long as it can distribute the potential of the electric wire 203a over the entire base material 270.

The structure of each voltage detection unit 80 will be described with reference to FIG. 7.
Each voltage detection unit 80 includes a voltage detection unit 260, a wireless transmission unit 81, and a battery 82.

The plate surface 40b of the verification electrode 40 is electrically connected to the voltage detection unit 260 by the detection pattern 203b. The voltage detection unit 260 is electrically connected to the main pattern 203D by the sub pattern 203d.
In the present embodiment, a part of the detection pattern 203b is provided inside the base material 270, but as a modification, it may be provided only on the surface 270a of the base material 270. Furthermore, in the present embodiment, a part of the sub-pattern 203d is provided inside the base material 270, but as a modification, the main pattern 203D is provided on the surface 270a of the base material 270, and the sub-pattern 203d is provided as the main pattern 203D. In addition, it may be provided only on the surface 270a of the base material 270. In this case, since it is not necessary to provide the pattern inside the base material 270, the pattern processing step is simplified.

  The voltage detection unit 260 detects a voltage between the connected electric wire 203a and the plate surface 40b of the verification electrode 40. The voltage may be detected all the time or only when necessary.

The wireless transmission unit 81 wirelessly transmits information based on the voltage detected by the voltage detection unit 260 to the processing unit 290. In the present embodiment, the wireless transmission unit 81 receives a signal corresponding to the voltage detected by the voltage detection unit 260 and converts it into a signal Sd corresponding to the voltage. The converted signal Sd is transmitted to the processing unit 290 by the wireless transmission unit 81. The signal Sd to be transmitted may be any signal as long as it is a signal correlated with the detected voltage, and may be an analog system, a digital system, or any system. Further, the transmission form may be any communication form such as light, radio wave, electromagnetic wave.
At this time, each wireless transmission unit 81 detects the identification information of the voltage detection unit 80 in which it is provided so that it can be identified from which voltage detection unit 80 the information based on the detected voltage. The information is sent to the processing unit 290 together with the information based on the voltage.

The battery 82 supplies necessary power to the wireless transmitter 81. If necessary, power may be supplied from the battery 82 to the voltage detection unit 260 as well. If the wireless transmitter 81 and the voltage detector 260 are supplied with necessary power by the battery 82, it is not necessary to provide a power supply wiring, and therefore the corrosion sensor 210 can be installed at any location on the surface 1a of the concrete structure 1. Can be installed.
In the present embodiment, each voltage detection unit 80 includes the battery 82. However, as a modified example, each voltage detection unit 80 is not provided with the battery 82, but a battery is provided for every several voltage detection units 80, and one battery is provided. May supply power to several voltage detection units 80.
If there is no difficulty in laying the power supply wiring, the power may be supplied to the plurality of voltage detection units 80 by the power supply wiring instead of the battery.

The processing unit 290 collects information based on the detected voltage sent from each voltage detection unit 80 and identification information of the voltage detection unit 80, and provides it to the worker.
In the present embodiment, the processing unit 290 stores in advance the relationship between the identification information of the voltage detection unit 80 and the position where each voltage detection unit 80 is installed. From the stored relationship, the processing unit 290 can use the identification information of the voltage detection unit 80 to associate the information based on the detected voltage with the position of the surface 1a of the concrete structure 1.
Therefore, by associating the information based on the detected voltage with the position of the surface 1a of the concrete structure 1, the processing unit 290 determines from the information sent from each voltage detection unit 80 the surface 1a of the concrete structure 1. It is possible to create map data of the natural potential or the corrosion level of.
The created map data is output by display, printing, etc. by the processing unit 290 and presented to the operator. The map data presented to the operator is presented by contour lines or a color map showing the relationship between the spontaneous potential and the position or the relationship between the corrosion level and the position.
In the present embodiment, the operator determines the corroded portion of the reinforcing bar 2 from the map data, reports the corrosion state, or repairs or maintains the corroded portion.
In the present embodiment, a mobile terminal such as a notebook computer, PDA, or tablet is used as the processing unit 290 so that information based on the voltage detected at any place can be confirmed.

<Fourth Embodiment>
A fourth embodiment of the corrosion sensor will be described with reference to FIG.
The corrosion sensor 10 of this embodiment is basically the same as that of the first embodiment, but the configuration of the electrode 30 is different.
FIG. 8 shows one of the plurality of electrodes 30 in detail. The configuration of FIG. 8 except for the protection unit 55 is the same as that of FIG.

  In the present embodiment, the electrode 30 arranged on the surface 1a of the concrete structure 1 is covered with the protective portion 55. With such a configuration, it is possible to suppress contact between the electrode 30 including the hot-melt electrode 50 and external moisture or salt, and thus a corrosion sensor with excellent long-term reliability is obtained. The protection part 55 may seal the entire electrode 30 including the base material 70 as shown in the example of FIG. Further, the protection part 55 may be disposed at least at the peripheral part of the electrode 30, and may protect the electrode 30 in combination with the base material 70. A known resin can be used for the protection part 55.

<Fifth Embodiment>
A fifth embodiment of the corrosion sensor will be described with reference to FIGS. 9A and 9B.
In the fifth embodiment, at least a part of the detection pattern 3b is formed by the pattern wiring 3c formed on the base material 70. That is, in the fifth embodiment, the electrode sheet with pattern wiring 300 including the pattern wiring 3c and the electrode 50 on the base material 70 is used. The pattern wiring 3c and the electrode 50 may be formed on the same surface, or the pattern wiring 3c may be formed on the surface opposite to the electrode 50 and connected through the opening of the base material.
The method of forming the pattern wiring 3c is, for example, a method of printing an ink containing a conductive material between the electrode 50 on the base material 70 and the detection portion 60 arranged on the side surface of the base material 70, or patterning. ,
Like a flexible circuit, a conductive metal is laminated on the base material 70 by vapor deposition, metal foil lamination, plating, or the like, a pattern is formed by etching, and a hot melt electrode 50 to be used next is formed, and wiring of the detection pattern 60 is formed. There is a method of connecting with.
If the contact resistance is small, the joint between the wiring pattern 3c and the electrode 50 can be directly connected by printing. If the contact resistance is high, the wiring may be connected with a conductive adhesive such as a silver paste or a metal filler. A protective portion 55 for sealing the wiring pattern may be further provided on the wiring pattern 3c, or may be wholly or partially laminated with a laminate film in which a base material having weather resistance and an adhesive are laminated. Good.
When the pattern wiring 3c is printed on the same surface as the electrode 50, the electrode can be formed at the end of the wiring, and the electrode can be partially or entirely exposed and heated and melted to be placed on the surface of the concrete structure 1. When the pattern wiring 3c is printed on the opposite surface of the electrode 50 of the electrode sheet with pattern wiring, a through hole is provided in the base material of the voltage detecting portion or the electrode portion, and conductive ink, a conductive adhesive, or a hot melt electrode is provided therein. It is also possible to join by embedding. In that case also, the protective portion 55 may be provided on the pattern wiring 3c, and the whole or part may be laminated with a laminating film in which a weather resistant base material and an adhesive are laminated.

  The conductive ink for printing the wiring pattern 3c contains at least conductive fine particles, and may contain other components such as a binder component and a solvent, if necessary.

  The conductive fine particles may be sintered to form a sintered body in the formed conductive wiring, but it is preferable that a plurality of conductive fine particles come into contact with each other to exhibit conductivity.

Examples of the conductive fine particles include metal fine particles, carbon fine particles, and conductive oxide fine particles.
Examples of the metal fine particles include, for example, gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, aluminum, tungsten, molbutene, and simple metal powders such as platinum, copper-nickel alloy, silver-palladium alloy, Examples thereof include alloy powders such as copper-tin alloys, silver-copper alloys, and copper-manganese alloys, and metal-coated powders obtained by coating the surface of the metal simple substance powder or alloy powder with silver or the like. Further, examples of the carbon fine particles include carbon black, graphite, carbon nanotubes and the like. Examples of the conductive oxide fine particles include silver oxide, indium oxide, tin oxide, zinc oxide, ruthenium oxide and the like. The conductive fine particles may be used alone or in combination of two or more.
In the present embodiment, from the viewpoint of long-term reliability of the conductive wiring, it is preferable to use fine carbon particles having excellent weather resistance such as water resistance and acid resistance.

  The shape of the conductive fine particles is not particularly limited, and an amorphous shape, an aggregate shape, a scale shape, a microcrystalline shape, a spherical shape, a flake shape, a wire shape, or the like can be appropriately used. The average particle size of the conductive fine particles is not particularly limited, but is preferably 0.1 μm or more and 50 μm or less, and 0.5 μm or more and 30 μm or less from the viewpoint of dispersibility in the conductive ink and conductivity after wiring. Is more preferable.

  The conductive ink preferably contains a binder component. As the binder component, it is preferable to include a resin from the viewpoint of film-forming property, adhesion after film-forming, flexibility and the like. The resin can be appropriately selected and used from resins used for conductive wiring. Examples of the resin include acrylic resin, vinyl ether resin, polyether resin, polyester resin, polyurethane resin, epoxy resin, phenoxy resin, polycarbonate resin, polyvinyl chloride resin, polyolefin resin, styrene block. A copolymer resin, a polyamide resin, a polyimide resin, etc. are mentioned, and they can be used individually by 1 type or in combination of 2 or more types.

The content ratio of the conductive fine particles in the pattern wiring 3c is preferably 50% by mass or more and 95% by mass or less, and more preferably 60% by mass or more and 90% by mass or less with respect to the total amount of the pattern wiring 3c. The content ratio of the binder component in the pattern wiring 3c is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less, based on the total amount of the pattern wiring 3c.
When the content ratio of the conductive fine particles is at least the above lower limit value, the conductive wiring has excellent conductivity. When the content ratio of the binder component is at least the above lower limit, film-forming property and adhesion to the base material 50 are improved, and flexibility can be imparted to the wiring pattern 3c of the electrode sheet with patterned wiring 300. it can.

The electrode sheet with pattern wiring 300c is prepared by, for example, preparing a conductive ink containing the conductive fine particles, the binder component, and optionally a solvent, and then printing the conductive ink on a substrate, It can be formed by removing the solvent if necessary.
The solvent may be appropriately selected according to the printing method. The printing method may be appropriately selected from known printing techniques such as a gravure printing method, a screen printing method, a flexo printing method, an inkjet method, and the like, depending on the composition of the conductive ink and the film thickness of the pattern wiring.

  The thickness of the conductive wiring of the electrode sheet with patterned wiring 300 is not particularly limited, and may be, for example, 1 μm or more and 500 μm or less, and preferably 10 μm or more and 300 μm or less, from the viewpoint of achieving both conductivity and flexibility. In addition, the width of the conductive wiring of the electrode sheet with the detection pattern is not limited, and may be a width that provides the necessary conductivity. For example, it can be 0.1 mm or more, and 1 mm to 100 mm is preferable. Note that the plurality of conductive wirings may have the same thickness or width, or may have different thicknesses or widths.

<Protective part (protective layer) of electrode sheet with pattern wiring>
The protective portion 55 of the electrode sheet with pattern wiring is provided at least on the wiring pattern 3c,
Scratch of the wiring pattern 3c and contact with water, oxygen, acid, alkali, etc. are suppressed, and long-term reliability is improved. The protective part 55 can be formed as a protective layer by, for example, laminating a sheet similar to the sheet base material of the electrode sheet with the detection pattern.

Further actions and effects of the corrosion sensor 210 of this embodiment will be described.
First, in the present embodiment, since a plurality of pairs of one electrode 30 and one voltage detection unit 80 are arranged in a grid pattern over the entire base material 270, the corrosion sensor 210 has a grid pattern on the surface 1 a of the concrete structure 1. The corrosion state of each point can be detected. Therefore, it is possible to measure the two-dimensional distribution of the corrosion state along the surface 1a of the concrete structure 1.
Further, in the present embodiment, by using the hot melt electrode 50, the corrosion state of the surface 1a of the concrete structure 1 can be measured in a short time and long-term monitoring is possible. In addition, since it is possible to wirelessly obtain information on the corrosion state, the worker can access the location of the surface 1a of the concrete structure 1 as long as he / she has the processing section 290, without going to the detection site for a long period of time. The self-potential or corrosion level can be monitored at any place, and the map data of the self-potential or corrosion level can be monitored at any place.
Further, if the processing unit 290 is configured by a mobile terminal, the processing unit 290 can head to the detection site that is determined to be the corroded site while checking the corroded site, so that the work efficiency of the repair and maintenance of the corroded site is improved. .

Furthermore, the corrosion sensor 210 and the processing unit 290 of this embodiment are wireless. The base material 270 is made of a flexible sheet.
Therefore, for example, when the corrosion sensor 210 is installed on the surface of the inner wall of the tunnel, only the corrosion sensor 210 as shown in FIG. 6 is brought into the tunnel and the corrosion sensor is simply attached to the inner wall of the tunnel with an adhesive, a pin or a staple. Since the installation of 210 is completed, the installation of the corrosion sensor 210 is easy.

  Further, since the corrosion sensor using the electrode sheet with patterned wiring 300 of the present embodiment has the detection pattern 3b provided on the base material in advance on the sheet, the corrosion sensor is used when performing large-area / multipoint natural potential measurement. Is even easier to install.

[Corrosion detection method]
The corrosion detection method of this implementation is
A corrosion detection method for detecting a corrosion state of a steel material in a concrete structure,
A preparatory step of preparing the corrosion sensor,
An electric wire provided in the corrosion sensor, an electric wire connecting step of electrically connecting with the steel material,
An adhesion step of adhering the electrode provided in the corrosion sensor to the surface of the concrete structure,
A voltage detecting step of detecting a voltage between the electrode and the steel material,
The adhering step includes a step of heating and melting the hot melt electrode.

Hereinafter, an embodiment of the corrosion detection method of the present invention will be described with reference to FIG.
In this embodiment, the steps shown in FIG. 10 are performed. This embodiment is implemented by applying any of the corrosion sensors 10, 110, or 210 to the concrete structure 1 having the reinforcing bars 2.

First, the corrosion sensor 10 is prepared (S1: preparation step). At this stage, the corrosion sensor may be prepared in a state where the electric wire, the electrode, and the voltage detection unit are electrically connected, or may be prepared as each component. In the present embodiment, the corrosion sensor may be prepared before the voltage detection step described later.
Next, an electric wire is electrically connected to the reinforcing bar 2 (S2: electric wire connecting step). Next, the electrode 30 and the surface 1a of the concrete structure 1 are electrically contacted via the hot melt electrode 50 (S3: bonding step). Then, the voltage between the electric wire and the plate surface 40b of the verification electrode 40 is detected by the voltage detection unit (S4: voltage detection step).
The detected voltage may be output as it is by display, printing or the like in the voltage detection unit and may be presented to the operator, but in the present embodiment, a step of wirelessly transmitting information based on the detected voltage to the processing unit. May be included (S5: wireless transmission step). The information based on the detected voltage is output by display, printing, etc. in the processing unit and presented to the operator.

  In the present embodiment, the bonding step includes a step of heating and melting the hot melt electrodes using a plurality of electrodes 30 having at least the hot melt electrodes 50. By such a method, even if the surface 1a of the concrete structure 1 has irregularities, the hot melt electrode 50 may be deformed along the irregularities during melting, and further fill the minute voids of the concrete structure 1. it can. As a result, good electrical contact is maintained with respect to the surface 1a of the concrete structure 1.

  The corrosion sensor of the present embodiment is not limited to a tunnel, and any concrete structure having a steel material can be applied. For example, it may be applied to concrete structures having steel materials such as bridges, bridge piers, and dams.

  Hereinafter, the present invention will be described specifically and in detail with reference to Examples, but these Examples are merely one aspect of the present invention, and the present invention is not limited to these Examples.

[Manufacture of electrodes for corrosion sensors]
<Production Example 1>
A hot melt resin based on SIS (styrene / isoprene / styrene) elastomer and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a polyimide film (Kapton 200EN: manufactured by Toray DuPont Co., Ltd.) to a thickness of 200 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 2 × 10 ¹ Ωcm.

<Production Example 2>
A hot melt resin based on SIS (styrene / isoprene / styrene) elastomer and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN (polyethylene naphthalate) film to a thickness of 100 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 3 × 10 ³ Ωcm.

<Production Example 3>
A hot-melt resin based on SEPS (styrene / ethylene / propylene / styrene) elastomer and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film with a thickness of 200 μm to obtain an electrode having a base material. The volume resistivity of the electrode part was 2 × 10 ⁻¹ Ωcm.

<Production Example 4>
A tabletop kneader equipped with a heating device was added with a hot-melt resin based on SEPS (styrene / ethylene / propylene / styrene) elastomer, a tackifier, a plasticizer and a carbon filler, and heated and stirred at 130 to 180 ° C for 3 hours. . It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a polyimide film with a thickness of 1000 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 2 × 10 ¹ Ωcm.

<Production Example 5>
A hot melt resin based on SEBS (styrene / ethylene / butylene / styrene) elastomer and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film with a thickness of 300 μm to obtain an electrode having a base material. The volume resistivity of the electrode part was 6 × 10 ¹ Ωcm.

<Production Example 6>
A hot melt resin based on a polyamide-based thermoplastic resin and a carbon filler were added to a desk kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film to a thickness of 150 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 5 × 10 ¹ Ωcm.

<Production Example 7>
A hot melt resin based on a polyester thermoplastic resin and a carbon filler were added to a desk kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film to a thickness of 500 μm to obtain an electrode having a base material. The volume resistivity of the electrode part was 4 × 10 ³ Ωcm.

<Production Example 8>
A hot melt resin based on a polyolefin thermoplastic resin and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film with a thickness of 250 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 1 × 10 ¹ Ωcm.

<Production Example 9>
A hot melt resin based on a polyurethane-based thermoplastic resin and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film to a thickness of 400 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 1 × 10 ¹ Ωcm.

<Production Example 10>
A hot melt resin based on a polyvinyl chloride (PVC) thermoplastic resin and a carbon filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot melt electrode was laminated on a PEN film with a thickness of 200 μm to obtain an electrode having a base material. The volume resistivity of the electrode portion was 1 × 10 ¹ Ωcm.

<Production Example 11>
A hot melt resin based on SEPS (styrene / ethylene / propylene / styrene) elastomer and a silver filler were added to a tabletop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180 ° C for 3 hours. It was confirmed that the elastomer did not remain unmelted, and a hot melt electrode was obtained. The prepared hot-melt electrode was laminated on a PEN substrate to a thickness of 200 μm to obtain an electrode. The volume resistivity of the electrode portion was 4 × 10 ⁻⁴ Ωcm.

<Production Example of Hot Melt Resin Composition and Sealant Sheet>
In a stainless beaker equipped with a stirrer, SIS as a thermoplastic resin was heated and melted at a temperature of 150 ° C. Then, stirring was performed to obtain a uniformly dispersed molten solution (hot melt resin composition 1). The hot melt resin composition 1 is sandwiched between release films, and hot pressed at 100 ° C. and 100 kgf / cm ² for 30 seconds by a tester industry tabletop test press machine to form a sheet having a film thickness of 200 to 300 μm and a sealing material. Sheet 1 was used.

<Production Example 12: Electrode sheet with pattern wiring>
As shown in FIG. 10, conductive carbon ink (carbon conductive paste RA FS 090: manufactured by Toyo Ink Co., Ltd.) on a substrate of a 300 mm × 100 mm polyamide film (Kapton 200EN: manufactured by Toray DuPont Co., Ltd.) with a width of 10 mm and four lines. Was printed with a space between lines of 5 mm to detect the pattern 303b and heat-dried at 100 ° C. for 30 minutes, and the hot melt electrode prepared in Example 1 was laminated on the substrate to a thickness of 200 μm so as to have a size of 40 mm × 40 mm. In addition, avoiding the electrode part, the encapsulant sheet is covered on the base material so as to cover the wiring part, and hot roll laminating is performed from above the release film at 150 ° C., 4 kgf / cm ² , 1 m / min to form the electrode and the carbon wiring. An electrode sheet with pattern wiring 300 including a sealing material was obtained (FIG. 10). The volume resistivity of the electrode portion was 2 × 10 ¹ Ωcm.

<Production Example 13: Electrode sheet with pattern wiring>
As shown in FIG. 10, a conductive silver paste (RA FS 007: manufactured by Toyo Ink Co., Ltd.) was used on a substrate of a 300 mm × 100 mm polyamide film (Kapton 200EN: manufactured by Toray DuPont Co., Ltd.) to form four 10 mm wide spaces between the lines. On the polyimide film (Kapton 200EN: manufactured by Toray-Dupont Co., Ltd.), the detection pattern 303b was printed at 5 mm, heat-dried at 100 ° C. for 30 minutes, and the hot-melt electrode prepared in Example 1 was 40 mm × 40 mm. To a thickness of 200 μm, and an encapsulant sheet is placed on the base material so as to cover the wiring part while avoiding the electrode part, and heat roll laminating is performed at 150 ° C., 4 kgf / cm ² , and 1 m / min from the release film. This was carried out to obtain an electrode sheet with pattern wiring 300 including electrodes, carbon wiring and a sealing material (FIG. 10). The volume resistivity of the electrode portion was 2 × 10 ¹ Ωcm.

<Production Example 14: Electrode sheet with pattern wiring>
As shown in FIG. 10, four lines with a width of 1 mm and a detection pattern 303b with a space between the lines of 5 mm are copper-etched on a substrate of a 300 mm × 100 mm single-sided polyimide copper clad laminate (F30-VC1: manufactured by Nikkan Industry Co., Ltd.). A polyimide coverlay film (Nikaflex CSKE base film thickness 25 μm: made by Nikkan Kogyo Co., Ltd.) is attached on the base material so as to avoid the electrode portion and cover the wiring portion, and the coverlay portion is 160 ° C. × 90 minutes. Then, the wiring portion was sealed by hot pressing with a molding pressure of 4 MPa. Further, the hot-melt electrode prepared in the example was laminated on the base material so as to have a size of 40 mm × 40 mm with a thickness of 300 mm, and the electrode and the wiring pattern with the copper wiring by etching and the electrode with pattern wiring provided with the encapsulant by the coverlay. A sheet 300 was obtained (Fig. 10). The volume resistivity of the electrode portion was 2 × 10 ¹ Ωcm.

<Comparative Production Example 1>
Ionic conductivity is obtained by laminating an ionic conductive gel obtained by mixing a high molecular polymer (Poly-b-ethylene oxide-b-styrene): PS-PEO-PS) and an ionic liquid on an aluminum foil. I got an electrode. The ionic conductivity of the electrode part was 4 × 10 ⁻² Scm.

<Example 1>
(Measurement)
1. Measurement of Volume Resistivity The laminate of the electrode and the polyimide film produced in Production Example 1 was cut into 1.5 cm × 3 cm, and a low resistivity meter (Mitsubishi Chemical Analytech Co., Ltd .: Lorester GX MCP-T700) was used. The volume resistivity of the electrode portion was measured. It measured 3 times and made the average value the measured value.

2. Measurement of Adhesive Strength The adhesive strength was measured by using a tensile tester EX-SX manufactured by Shimadzu Corporation. A sheet of 25 mm width composed of a laminate of a hot melt electrode having a thickness of 200 μm and a polyimide film obtained in Production Example 1 was subjected to a surface polishing treatment with a grinder to obtain a 7 cm × 7 cm concrete adherend surface, which was hot. The melt electrode side was attached, and a plate heated to 200 ° C. was pressed against the base material for 1 minute to adhere to the concrete. After the heating was completed, the sample was allowed to stand for 24 hours until it returned to room temperature, which was used as a measurement sample. The measuring method was such that the edge of the sheet was at an angle of 90 degrees and a speed of 50 mm / min. The adhesive force was evaluated from the load when peeled off with.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

3. Compound Corrosion Resistance Test As the compound corrosion test, a test based on the Japan Automobile Manufacturers Association Standard (JASO) M609 / M610 was carried out for a long time. Specifically, the sample was placed inside the complex corrosion tester (BQD-2) in a state of being inclined at 70 degrees with respect to the ground. The complex corrosion condition of the sample is as follows: 5% NaCl, salt spray at 35 ° C for 2 hours, then 4 hours in a dry environment of 50% RH and 60 ° C, and a wet environment of 95% RH and 50 ° C. I put it down for two hours. This cycle was performed 200 times. After the implementation, the measurement sample was collected, and the deterioration determination was performed by comparing the results before and after the following test.

A. Change in conductivity Samples for measurement of complex corrosion test are 1. It was prepared in the same manner as the measurement of the volume resistivity, and at the same time, the resistivity was also measured. The sample was put into a complex corrosion tester, a corrosion cycle test was performed under the above conditions, and then the volume resistivity of the sample was measured by the same method.
◎ when the volume resistivity is less than 1 × 10 ³ Ωcm before and after the complex corrosion test, ◯ when the volume resistivity is less than 1 × 10 ⁵ Ωcm before and after the complex corrosion test, and other In the case of, it was marked with x.

B. Change in Adhesiveness The measurement sample prepared in Example 1 in which the hot melt electrode adhered to concrete was subjected to a corrosion cycle test under the above conditions, and then the adhesive strength was evaluated by the same method. When the adhesive strength before the test is 10 N or more and the decrease in the adhesive strength value after the corrosion test is less than 10 N, the adhesive strength before the test is 5 N or more and the adhesive strength value after the corrosion test decreases by less than 5 N. In other cases, it was ◯, and in other cases, it was x.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

4. Spontaneous potential measurement (Self-potential measurement noise / reinforcement deterioration detection)
The hot melt electrode site was pasted on the surface of the reinforced concrete of the laminate composed of the hot melt electrode and the polyimide film prepared in Example 1, and the concrete surface was obtained by applying pressure with a flat plate in a state of heating from 150 ° C. to 250 ° C. from above. Glued to. The measurement was made possible by connecting a voltmeter between the electrode and a lead wire connected to the reinforcing bar in the concrete. At this time, the conductive wire joint portion with the reinforcing bar was protected by a sealing material so that the conductive wire portion did not get wet. Corrosion of the reinforcing bar portion was promoted by ebbing the water level of the water tank every 6 hours.
When the noise level during potential measurement was less than 20 mV, the spontaneous potential measurement noise was rated as ⊚, when it was 20 mV or more and less than 50 mV, as ◯, and when 50 mV or more was rated as x.
Furthermore, when the potential changed negatively by 50 mV or more within one day during the potential measurement and internal rust of the reinforcing bar was confirmed, the self-potential reinforcing bar deterioration detection was marked with ◯, and the other cases were marked with x.

<Comparative Example 1>
The following measurements were performed using the ion gel electrode prepared in Comparative Production Example 1 laminated on an aluminum substrate with a thickness of 500 μm. The conductivity was evaluated using the AC impedance method.

<Measurement>
1. Measurement of ionic conductivity The ionic conductivity of the ion gel electrode prepared in Comparative Production Example 1 was measured using an impedance analyzer. It measured 3 times and made the average value the measured value.

2. Measurement of Adhesive Strength The adhesive strength was measured by using a tensile tester EX-SX manufactured by Shimadzu Corporation. To a concrete adherend surface of 7 cm × 7 cm, which was obtained in Comparative Production Example 1, a sheet of 25 mm width composed of a laminate of an ion gel electrode having a thickness of 500 μm and an aluminum base material was surface-polished with a grinder. Adhesion was performed by sticking the ion gel electrode side. The measuring method of the adhesive force is as follows: the edge of the sheet is at an angle of 90 degrees and the speed is 50 mm / min. The adhesive force was evaluated from the load when peeled off with.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

3. Compound Corrosion Resistance Test As the compound corrosion test, a test based on the Japan Automobile Manufacturers Association Standard (JASO) M609 / M610 was carried out for a long time. Specifically, the sample was placed inside the complex corrosion tester (BQD-2) in a state of being inclined at 70 degrees with respect to the ground. The complex corrosion condition of the sample is as follows: 5% NaCl, salt spray at 35 ° C for 2 hours, then 4 hours in a dry environment of 50% RH and 60 ° C, and a wet environment of 95% RH and 50 ° C. I put it down for two hours. This cycle was performed 200 times. After the implementation, the measurement sample was collected, and the deterioration determination was performed by comparing the results before and after the following test.

A. Change in conductivity Samples for measurement of complex corrosion test are 1. It was prepared in the same manner as the measurement of ionic conductivity, and at the same time, the resistivity was also measured. The sample was put into a complex corrosion tester, a corrosion cycle test was performed under the above conditions, and then the conductivity of the sample was measured by the same method. When the ionic conductivity is 1 × 10 ⁻³ S / cm or more before and after the complex corrosion test, ◎, and the ionic conductivity is 1 × 10 ⁻⁵ S / cm or more before and after the complex corrosion test. In other cases, it was ◯, in other cases, it was x.

B. Change in Adhesiveness The measurement sample prepared in Comparative Example 1 in which the ion gel electrode adhered to concrete was subjected to a corrosion cycle test under the above conditions, and then the adhesive strength was evaluated by the same method. When the adhesive strength before the test is 10 N or more and the decrease in the adhesive strength value after the corrosion test is less than 10 N, the adhesive strength before the test is 5 N or more and the adhesive strength value after the corrosion test decreases by less than 5 N. In other cases, it was ◯, and in other cases, it was x.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

4. Spontaneous potential measurement (Self-potential measurement noise / reinforcement deterioration detection)
The ion gel electrode prepared in Comparative Example 1 was attached to the surface of reinforced concrete to adhere it to the concrete surface. The measurement was made possible by connecting a voltmeter between the electrode and a lead wire connected to the reinforcing bar in the concrete. At this time, the conductive wire joint portion with the reinforcing bar was protected by a sealing material so that the conductive wire portion did not get wet. Corrosion of the reinforcing bar portion was promoted by ebbing the water level of the water tank every 6 hours.
When the noise level during potential measurement was less than 20 mV, the spontaneous potential measurement noise was rated as ⊚, when it was 20 mV or more and less than 50 mV, as ◯, and when 50 mV or more was rated as x.
Furthermore, when the potential changed negatively by 50 mV or more within one day during the potential measurement and internal rust of the reinforcing bar was confirmed, the self-potential reinforcing bar deterioration detection was marked with ◯, and the other cases were marked with x.

<Examples 2 to 13, Comparative Example 1>
In the same manner as in Example 1, Examples 2 to 13 and Comparative Example 1 were manufactured and measured. The results are shown in Table 2.

1: Concrete structure 1a: Surface 2: Reinforcing bar 3a: Electric wire 3b: Detection pattern 3c: Wiring pattern 5: Corrosion detection system 10: Corrosion sensor 20: Contact point 30: Electrode 40: Verification electrode 40a: Plate surface 40b: Plate surface 50 : Hot melt electrode 55: Protection part 60: Voltage detection part 70: Base material 80: Voltage detection unit 81: Wireless transmission part 82: Battery 90: Processing part 105: Corrosion detection system 110: Corrosion sensor 170: Base material 170a: Surface 203a: Electric wire 203b: Detection pattern 203d: Sub pattern 203D: Main pattern 205: Corrosion detection system 210: Corrosion sensor 260: Voltage detection unit 270: Base material 270a: Front surface 270b: Back surface 290: Processing unit Sd: Signal 300: Pattern wiring Attached electrode sheet 303b: detection pattern

Claims (11)

A corrosion sensor for detecting a corrosion state of a steel material in a concrete structure,
An electric wire electrically connected to the steel material,
An electrode arranged on the surface of the concrete structure,
A voltage detection unit for detecting a voltage between the electrode and the electric wire,
A corrosion sensor, wherein the electrode has a hot melt electrode containing a hot melt resin in which a conductive filler is dispersed.   The corrosion sensor according to claim 1, wherein the conductive filler is silver or conductive carbon.   The corrosion sensor according to claim 1, wherein the hot melt resin contains a thermoplastic elastomer.   The corrosion sensor according to claim 1, wherein the electrode further has a reference electrode on the hot melt electrode.   The corrosion sensor according to claim 1, further comprising a base material on the electrode.   The corrosion sensor according to any one of claims 1 to 5, which has a plurality of the electrodes, and the plurality of electrodes are arranged in a pattern on a sheet-shaped base material.   The corrosion sensor according to claim 1, further comprising a wireless transmission unit that wirelessly transmits information based on the detected voltage.   The corrosion sensor according to claim 7, wherein the wireless transmission unit further includes a battery that supplies electric power.   9. The electrode according to claim 5, wherein the electrode and the voltage detection unit are connected by a detection pattern, and at least a part of the detection pattern is a pattern wiring formed on at least one surface of the base material. The corrosion sensor according to the item. A corrosion detection method for detecting a corrosion state of a steel material in a concrete structure,
A preparatory step of preparing the corrosion sensor according to any one of claims 1 to 9,
An electric wire provided in the corrosion sensor, an electric wire connecting step of electrically connecting with the steel material,
An adhesion step of adhering the electrode provided in the corrosion sensor to the surface of the concrete structure,
A voltage detection step of detecting a voltage between the electrode and the electric wire,
The corrosion detecting method, wherein the adhering step includes a step of heating and melting the hot melt electrode. The preparation step is a preparation step of preparing the corrosion sensor according to claim 7 or 8,
The corrosion detection method according to claim 10, further comprising a step of wirelessly transmitting information based on the detected voltage after the voltage detection step.

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