JP7284952B2 - Chloride ion sensor and method for measuring chloride ion concentration - Google Patents

Description

The present invention relates to a chloride ion sensor for detecting chloride ions in concrete structures and a chloride ion concentration measuring method.

Deterioration of metals such as reinforcing bars installed in concrete structures may be accelerated depending on the surrounding environment. For example, it is known that corrosion of the metal is likely to be accelerated in an environment with a high chloride ion concentration. Therefore, a non-destructive method for measuring the chloride ion concentration in concrete structures has been investigated.

A conductive method is known as one of methods for measuring the chloride ion concentration in a concrete structure. In the conduction method, the impedance of the concrete structure and the phase angle peak frequency of the impedance are measured while an alternating current is flowing through the target concrete structure, and the moisture content of the concrete structure is measured. This is a method of calculating the chloride ion concentration in combination with the information of

Various measurement devices and measurement systems have been proposed for use in the conductive method.
For example, Patent Document 1 discloses characteristic information storage means for storing information about the characteristics of a concrete body, a pair of electrodes spaced apart from each other on the surface of the concrete body, and a pair of electrodes between the pair of electrodes. a measurement means for measuring impedance or peak frequency in a state in which an alternating current is passed through the concrete body, and based on the measured values such as impedance measured using the measurement means, the salinity is determined by referring to the characteristic information A concrete body salinity measurement system is disclosed that determines the concentration. The characteristic information includes, for example, characteristic information that associates the impedance, the peak frequency of the impedance, the moisture content, and the salinity concentration with each other. According to Patent Literature 1, the above system enables the user to go to the building to be measured and measure the salt content of the concrete in a simple and real-time manner.

Further, Patent Document 2 discloses a pair of electrodes spaced apart from each other on the surface of a concrete body, an impedance when an alternating current is applied between the pair of electrodes through the concrete body, measuring means for measuring the phase angle peak frequency at which the phase angle of the impedance peaks; moisture information acquiring means for acquiring the moisture content of the concrete body or the amount of water vapor in the environment in which the concrete body is placed; The chloride concentration of the concrete body is determined based on the impedance and the phase angle peak frequency measured by the measuring means, and the plurality of moisture percentages or the plurality of water vapor amounts acquired by the moisture information acquisition means. Chloride in a concrete body, comprising: calculating means for calculating an evaluation value for evaluation; and specifying means for specifying the chloride concentration of the concrete body based on the evaluation value calculated by the calculating means. A concentration measurement system is disclosed. According to Patent Document 2, the chloride concentration of a concrete body is accurately measured by considering the influence of external factors such as impedance and phase angle peak frequency, which are easily affected by external factors such as the amount of water vapor. is said to be possible.
In addition, in the systems of Patent Documents 1 and 2, brass is used as the electrodes.

JP 2012-184948 A Patent No. 6338238

Long-term monitoring of chloride ion concentration is necessary to estimate the state of metals such as reinforcing bars installed in concrete structures. The present inventors installed a chloride ion sensor in a concrete structure and examined long-term monitoring at a fixed point. However, there is a problem that the electrodes placed on the concrete structure surface are easily deteriorated by the chloride ions in the concrete.

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

The present inventors have completed the present invention based on the knowledge that the above problems can be solved by using an electrode that is excellent in weather resistance and adhesiveness to the surface of concrete.

That is, the chloride ion sensor of this embodiment is a sensor for measuring the chloride ion concentration in a concrete structure,
at least a pair of electrodes spaced apart from each other on the surface of the concrete structure;
a measuring unit that measures impedance in a state in which an alternating current is passed between the at least one pair of electrodes;
The at least one pair of electrodes has a hot melt electrode containing a hot melt resin in which a conductive filler is dispersed.

In one embodiment of the chloride ion sensor, the conductive filler is silver or conductive carbon.

In one embodiment of the chloride ion sensor, the hot melt resin contains a thermoplastic elastomer.

In one embodiment of the chloride ion sensor, the electrode has a conductive layer on the hot melt electrode.

One embodiment of the chloride ion sensor includes:
One embodiment of the chloride ion sensor further comprises a substrate over the electrode.

In one embodiment of the chloride ion sensor, the electrodes are sheeted.

One embodiment of the chloride ion sensor has a plurality of the electrodes, and the plurality of electrodes are arranged in a pattern on a sheet-like base material.

In one embodiment of the chloride ion sensor, the electrodes and the measurement unit are connected by conductive wiring, and at least part of the conductive wiring is pattern wiring formed on at least one surface of the base material. be.

One embodiment of the chloride ion sensor further comprises a wireless transmitter for wirelessly transmitting information based on the detected impedance.

In one embodiment of the chloride ion sensor, the wireless transmitter further comprises a battery for powering.

The chloride ion concentration measuring method of this implementation is a measuring method for measuring the chloride ion concentration in a concrete structure,
a preparation step of preparing the chloride ion sensor;
a bonding step of respectively bonding at least a pair of electrodes included in the chloride ion sensor to the surface of the concrete structure;
a measuring step of measuring an impedance in a state in which an alternating current is passed through a concrete body between the at least one pair of electrodes,
The adhering step includes a step of adhering the hot-melt electrode to a concrete structure by heating and melting the hot-melt electrode.

An embodiment of the chloride ion concentration measurement method further includes a calculation step of calculating the chloride ion concentration from the measured impedance,
The calculating step calculates the chloride ion concentration based on at least the measured impedance obtained by the impedance measuring step.

In one embodiment of the chloride ion concentration measuring method, the preparation step is a preparation step of preparing the chloride ion sensor according to claim 7 or 8,
The step of wirelessly transmitting information based on the measured impedance obtained by the step of measuring the impedance is further included.

According to the present invention, it is possible to provide a chloride ion sensor capable of long-term monitoring and a chloride ion concentration measuring method.

1 is a schematic diagram of a chloride ion sensor of a first embodiment; FIG. It is a schematic diagram showing an installation example of a chloride ion sensor. It is a schematic diagram of a chloride ion sensor of a second embodiment. It is the schematic of the chloride ion sensor of 3rd Embodiment. It is a block diagram which shows an example of a calculating part. It is a flow chart which shows an example of a chloride ion concentration measuring method. It is a schematic sectional drawing which shows an example of the electrode 1a. FIG. 4 is a schematic cross-sectional view showing another example of an electrode 1a; FIG. 11 is a schematic front view of an electrode sheet provided with wiring patterns in a fourth embodiment; 9B is a side view of FIG. 9A; FIG.

[Chloride ion sensor]
The chloride ion sensor of this implementation is
at least a pair of electrodes spaced apart from each other on the surface of the concrete structure;
a measuring unit that measures impedance in a state in which an alternating current is passed between the at least one pair of electrodes;
The at least one pair of electrodes has a hot melt electrode containing a hot melt resin in which a conductive filler is dispersed.

The chloride ion sensor of the present embodiment can be installed in a concrete structure for a long period of time (for example, 3 months or more) by configuring as described above, and can be monitored over a long period of time. can do.
The chloride ion sensor of the present embodiment measures impedance with at least a pair of electrodes in a state in which an alternating current is applied to a concrete structure to be measured. The chloride ion concentration is measured by referring to a concrete characteristic information database (hereinafter sometimes referred to as a characteristic information DB) prepared in advance, which includes the relationship between impedance, moisture content, and chloride ion concentration. It is calculated from the impedance
In the following, regarding the chloride ion sensor of this embodiment, the electrodes will be described first, and then each embodiment will be described with reference to the drawings.

In this embodiment, the frequency is the frequency corresponding to the impedance, and more specifically, the frequency of the alternating current applied to the concrete structure during the impedance measurement. The peak frequency is the frequency at which the impedance phase angle peaks. Moisture content means the amount of water per unit volume in a range from the surface of a concrete structure to a predetermined depth (for example, 20 mm). Also, the amount of water vapor means the amount of water vapor in the environment in which the concrete structure is arranged, and can be calculated from humidity and temperature with reference to a vapor pressure curve.

<Electrode>
The electrode used in the chloride ion sensor of this embodiment has a hot-melt electrode containing at least a hot-melt resin in which a conductive filler is dispersed. It is acceptable. Each configuration of such an electrode will be described below.

(hot melt electrode)
In this embodiment, the hot-melt electrode is used by being placed on the surface of the concrete structure.
In this embodiment, the hot-melt electrode is melted by heating, attached to the surface of the concrete structure, and then cooled and solidified. Therefore, it is held stably in close contact with the surface of the concrete structure. Moreover, since the hot-melt electrode fills the voids on the surface of the concrete structure, the contact resistance is suppressed. In addition, since the conductive filler is dispersed in the hot-melt resin, it is held in the electrode without dissociating from the electrode and penetrating into the concrete structure. Therefore, the hot-melt electrode of the present embodiment has little change in state on the surface of the concrete structure, and can stably measure the voltage. Therefore, a chloride ion sensor capable of long-term monitoring can be obtained by using the electrode.

The hot-melt electrode of this embodiment contains at least a hot-melt resin and a conductive filler, and may further contain other components as necessary. Each component contained in such a hot-melt electrode will be described below.

(1) Hot-melt resin In this embodiment, the hot-melt resin includes a resin that can be melted by heating when installing the electrode on the surface of the concrete structure, and a known thermoplastic resin can be used as such a resin. can be done.

Examples of thermoplastic resins include polyurethane-based resins, acrylonitrile-based resins, acrylic-based resins, polyamide-based resins, polyvinyl butyral-based resins, polyester-based resins, styrene-based resins, silicone-based resins, and thermoplastic elastomers. A single species or a combination of two or more species can be used.

In this embodiment, the hot-melt resin preferably contains a thermoplastic elastomer. By containing a thermoplastic elastomer, the electrode can have rubber elasticity at room temperature (for example, 25° C.). Having rubber elasticity suppresses breakage of the electrode, making it possible to obtain a chloride ion sensor capable of long-term monitoring. The elastic modulus of the thermoplastic elastomer at room temperature can be, for example, 0.1 to 100 MPa.

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

In this 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 this embodiment, the weight average molecular weight is the polystyrene equivalent molecular weight measured using GPC (gel permeation chromatography) "HLC-8320" manufactured by Tosoh Corporation.

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

(2) Conductive Filler In this embodiment, the conductive filler is dispersed in the hot-melt resin and used 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 (scale), spherical, needle, fibrous, and dendritic. From the viewpoint of ensuring conductivity while reducing the content ratio of the conductive filler, it is preferable to use flaky conductive filler.

Materials for the conductive filler include, for example, 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, and indium oxide; organic substances such as polypyrrole, polythiophene, polyaniline, and oligothiophene; carbon black, graphite, graphene, graphite, carbon nanotube, carbon fiber, fullerene, graphene oxide , conductive carbon such as acetylene black, inorganic insulators such as alumina and glass, and polymer surfaces such as polyethylene and polystyrene coated with a conductive material. In this implementation, the conductive filler can be used singly or in combination of two or more.

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

The content of the conductive filler is preferably 2 to 60% by mass, more preferably 5 to 40% by mass, based on 100% by mass of the hot-melt electrode, from the viewpoint of conductivity and adhesiveness.
Although the thickness of the hot-melt electrode is not particularly limited, it 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 effects are not impaired. Other suitable ingredients include tackifiers, plasticizers, and the like. A hot-melt electrode containing a tackifier or a plasticizer is imparted with tackiness, so that it can be temporarily fixed to a concrete surface, facilitating installation during adhesion. The tackifier and plasticizer can be appropriately selected from known ones and used alone or in combination of two or more. Also, the tackifier and the plasticizer may be used alone or in combination.
When the hot melt electrode contains a tackifier or plasticizer, the total content is preferably 0.5% by mass or more and 40% by mass or less, and 1% by mass or more and 20% by mass, based on the total amount of 100% by mass of the hot melt electrode. % or less is more preferable.

In addition, the hot melt electrode of the present embodiment further includes other components such as a silane coupling agent, a titanate coupling agent, a softening agent, a flame retardant, a storage stabilizer, an antioxidant, and a metal deactivator. agent, ultraviolet absorber, thixotropy imparting agent, leveling agent, antifoaming agent, dispersion stabilizer, fluidity imparting agent, antifoaming agent, antiblocking agent, flame retardant, colorant and the like. When the hot-melt electrode contains these components, the content is preferably 5% by mass or less, more preferably 3% by mass or less, based on 100% by mass of the total amount of the hot-melt electrode.

(other configuration)
In this embodiment, the electrode may have a structure having only the hot-melt electrode, or may have other structures such as a conductive layer, if necessary.

The conductive layer is provided on the surface of the hot-melt electrode opposite to the surface of the concrete structure. Since the conductive layer does not come into direct contact with the surface of the concrete structure, the influence of corrosion due to chloride ions in the concrete structure is suppressed. Therefore, the conductive layer can have any configuration. Examples of the conductive layer include a silver/silver chloride electrode layer, a silver/silver chloride electrode layer containing carbon flakes, and a conductive foil such as a metal foil.

Moreover, you may have a base material further on the electrode. The substrate is usually placed on the surface of the hot-melt electrode opposite to the surface of the concrete structure, and if it has the conductive layer, it is placed on the conductive layer. The base material improves the handleability during electrode production, and also functions as a protective film for the hot-melt electrode and the conductive layer when the electrode is used.
In this embodiment, the substrate is not limited, and can be appropriately selected from, for example, various resin films. Materials for the substrate include, for example, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, polyethersulfone, polyethylene naphthalate, polybutylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, cycloolefin polymer, ABS ( acrylonitrile-butadiene-styrene copolymer resin), AES (acrylonitrile-ethylene-styrene copolymer resin), Kaidac (acrylic-modified vinyl chloride resin), modified polyphenylene ether, and films such as polymer alloys composed of two or more of these resins, Laminated films of these and the like are included. The substrate may be transparent or opaque. It is preferable that the base material has flexibility because it can easily follow the unevenness of the concrete surface.

(Method for manufacturing electrode)
An example of the method for manufacturing the electrode in this embodiment is shown below.
As an example of the electrode manufacturing method, first, the hot-melt resin, the conductive filler, and optionally other components are mixed to form a mixture. The mixture may contain a solvent that dissolves the hot melt resin for uniform dispersion.
Next, the mixture is dispersed by a known dispersing machine to form a dispersion. Examples of the dispersing machine include roll mills such as two-roll and three-roll roll mills, ball mills such as ball mills and vibrating ball mills, bead mills such as paint conditioners, continuous disk-type bead mills, and continuous annular-type bead mills.
The resulting dispersion is then applied onto a substrate. The coating method may be appropriately selected according to the thickness, material, etc. 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, reverse 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 coating film as necessary.
When the base material is unnecessary, the base material may be peeled off after forming the same coating film as described above using a peelable base material. When the electrode has a conductive layer, the hot-melt electrode may be formed by forming the conductive layer on the substrate and then coating the conductive layer with the dispersion for the hot-melt electrode.

The electrodes formed by the above method are sheeted. Further, by printing the hot-melt electrode in a pattern by the above method, a plurality of electrodes can be arranged in a pattern on one sheet-like substrate. By arranging a plurality of electrodes in a pattern, it is not necessary to adjust the spacing between paired electrodes. In addition, by arranging a plurality of electrodes on one sheet-like base material, installation becomes easy even when arranging a plurality of chloride ion sensors on a concrete structure.

<Embodiment of chloride ion sensor>
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a chloride ion sensor according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a first embodiment of the chloride ion sensor of the present invention. A chloride ion sensor 10 shown in the example of FIG. electrodes 1a and 1b each comprise a hot melt electrode.
The distance between the electrodes 1a and 1b is an arbitrary distance within a range in which the impedance can be measured with an alternating current flowing through the concrete structure 100, and is, for example, in the range of 1 to 100 mm. As a tendency, the wider the distance between the pair of electrodes 1a and 1b, the deeper the concrete structure can be measured.

The configuration of the electrodes will now be described with reference to FIGS. 7 and 8. FIG. FIG. 7 is a schematic cross-sectional view showing an example of the electrode 1a. The electrode 1a shown in FIG. 7 is a laminate in which a conductive layer 5 and a substrate 6 are laminated in this order on a hot-melt electrode 4. It is sufficient if the electrode 4 is provided.
Further, in the example of FIG. 8, the electrode 1a arranged on the surface of the concrete structure 100 is covered with the protective portion 7. As shown in FIG. With such a configuration, contact between the electrode 1a including the hot-melt electrode 4 and external moisture or salt content can be suppressed, resulting in a chloride ion sensor with superior long-term reliability. The protection part 7 may seal the entire electrode 1a including the substrate 6 as shown in the example of FIG. Moreover, the protection part 7 may be disposed at least on the peripheral edge of the electrode 1a and may be combined with the base material 6 to protect the electrode 1a. A known resin can be used for the protection portion 7 . The details of the hot-melt electrode 4, the conductive layer 5, and the base material 6 are as described above, and the description thereof will be omitted here.

The measurement unit 2 applies an alternating current between at least a pair of electrodes 1a and 1b through the concrete structure 100, and measures the impedance in the state in which the alternating current is applied, and, if necessary, the frequency and peak frequency. do. A known impedance meter (LCR meter) can be used as the measurement unit 2 . Moreover, the measurement unit 2 may be configured by combining an oscillator, an ammeter, and the like.
The impedance meter is measuring means for measuring impedance or peak frequency in a state in which an alternating current is passed between at least a pair of electrodes 1a and 1b through the concrete structure 100. FIG. Although the measurement principle of this impedance meter is arbitrary, the impedance can be measured by a known method such as a bridge method or a resonance method. A two-terminal method impedance meter uses a pair of electrodes (two electrodes). Also, in the four-terminal method impedance meter, two pairs of electrodes (four electrodes) are used.
The measurement unit 2 may normally be connected to the calculation unit 50 to constitute a chloride ion sensor system. In the example of FIG. 1 , the measurement section 2 and the calculation section 50 are connected by a wiring 21 . The impedance and the like measured by the measurement unit 2 are input to the calculation unit 50, and the chloride ion concentration is calculated by the calculation unit 50. The calculation unit 50 will be described later.

The concrete structure 100 to be measured in this embodiment is not particularly limited. The concrete structure 100 to be measured usually contains chloride ions and moisture, and further has reinforcing bars inside. The structure of the concrete structure 100 is arbitrary, and may be flat or curved, and may have unevenness or the like. Since the electrodes 1a and 1b of the chloride ion sensor 10 of this embodiment have hot-melt electrodes, they can adhere to any shape. Specific examples of the concrete structure 100 include tunnels, bridges, bridge piers, dams, and concrete structures constituting at least part of other buildings.

FIG. 2 shows an example in which the chloride ion sensor 10 of this embodiment is arranged on the inner wall 101 of the tunnel. The chloride ion sensor 10 of this embodiment may be arranged singly on the inner wall 101 of the tunnel, or two or more may be connected as shown in the example of FIG. The connected chloride ion sensor 20 can be manufactured, for example, by providing a plurality of measurement units 2 on electrodes arranged in a pattern on a sheet-like base material 31 . The use of linked chloride ion sensors 20 facilitates placement of each chloride ion sensor 10 at predetermined predetermined intervals.

Also, as shown in the example of FIG. 2, linked chloride ion sensors 20 may share wiring 22 . The wiring 22 is, for example, wiring that connects the measurement unit 2 and the calculation unit 50, wiring that connects the measurement unit 2 and a wireless transmission unit 3, which will be described later, and each chloride ion sensor 10 and an external power supply (not shown). Wiring etc. to connect are mentioned. When the connected chloride ion sensors 20 share the wiring 22 , they may also share the computing unit 50 and the wireless transmission unit 3 .

Furthermore, as shown in the example of FIG. 2, a plurality of connected chloride ion sensors 20 can be provided within the tunnel at predetermined intervals. By providing a plurality of linked chloride ion sensors 20, the chloride ion concentration throughout the tunnel can be mapped.
Multiple linked chloride ion sensors 20 as shown in the example of FIG. 2 may share wiring 23 . As with the wiring 22, the wiring 23 is, for example, a wiring that connects the measurement unit 2 and the calculation unit 50, a wiring that connects the measurement unit 2 and a wireless transmission unit 3 described later, each chloride ion sensor 10 and an external power supply. (not shown). A plurality of connected chloride ion sensors 20 may further share the calculation unit 50 and the wireless transmission unit 3 .

An example of the calculation unit 50 is shown in FIG. In the example of FIG. 5, the calculation unit 50 includes an input unit 51, an output unit 52, a storage unit 53, a calculation unit 54, and a control unit 55. As the calculation unit 50, for example, a known personal computer, PDA, tablet terminal, or the like can be used.

The input unit 51 is input means for receiving input of various kinds of information necessary for executing the measuring method according to the present embodiment, and it is sufficient if it has at least a terminal connected to the measuring unit 2. If necessary, a keyboard, a touch panel, a terminal connected to a moisture content meter 61, which will be described later, and various switches may be provided.

The output unit 52 is output means for outputting various kinds of information necessary for executing the measurement method according to the present embodiment, and is configured as a monitor or the like, for example.

The storage unit 53 is storage means for storing various kinds of information necessary for the processing of the calculation unit 50, and is configured by, for example, a hard disk or other recording medium. In this embodiment, a characteristic information DB 40 is provided. The characteristic information DB 40 stores characteristic information specifying the correlation between the impedance, the frequency corresponding to the impedance, the moisture content, and the chloride ion concentration of the concrete structure 100, or the impedance phase angle at the peak. It contains characteristic information specifying the interrelationship between peak frequency, moisture content, and chloride ion concentration. The characteristic information can be acquired, for example, by measuring the impedance and frequency of the concrete structure 100 whose moisture content and salinity are known in advance, or the peak frequency at which the impedance phase angle peaks. Also, for example, it may be obtained from known documents such as Japanese Patent Application Laid-Open No. 2012-184948 and Japanese Patent No. 6338238.
The characteristic information DB 40 does not need to store all raw data, and may store only a part of raw data and generate other data by interpolation as needed. For example, when storing data indicating the relationship between frequency and impedance, only impedances corresponding to multiple intermittent frequencies are stored as raw data, and impedances corresponding to frequencies between these multiple frequencies are stored as raw data. , may be generated by interpolation based on the raw data.

The calculation unit 54 calculates the characteristic information stored in the characteristic information DB 40 based on the impedance measured using the measurement unit 2 and the frequency corresponding to the impedance, or the peak frequency at which the phase angle of the impedance peaks. By referring to them, the moisture content and the chloride ion concentration of the concrete structure 100 are calculated. Specifically, the calculation unit 54 includes a CPU, various programs interpreted and executed on the CPU (including a basic control program such as an OS, and an application program started on the OS and realizing a specific function), and It is configured with an internal memory such as a RAM for storing programs and various data. In particular, the chloride ion concentration calculation program according to the present embodiment is stored in a readable recording medium and installed in the computing device 5 from the recording medium, thereby substantially configuring the calculation unit 54 .

In addition, the control unit 55 controls each unit that configures the calculation unit 50, and controls the measurement unit 2 to start and end measurement, and the like. Like the calculation unit 54, the control unit 55 includes a CPU, various programs interpreted and executed on the CPU, and an internal memory such as a RAM for storing programs and various data.

(Second embodiment)
FIG. 3 is a schematic diagram showing a second embodiment of the chloride ion sensor of the present invention. The chloride ion sensor 10 shown in the example of FIG. 3 is different from the first embodiment in that it includes a wireless transmission section 3 and the wireless transmission section 3 and the measurement section 2 are connected.
The wireless transmission unit 3 wirelessly transmits information such as impedance measured by the measurement unit 2 to the calculation unit 50 . The signal to be transmitted is not particularly limited, and may be either an analog system or a digital system. Any form of transmission, such as light, radio waves, or electromagnetic waves, may be used.
When there are a plurality of chloride ion sensors 10 as in the example of FIG. 2, each wireless transmission unit 3 transmits the identification information of the chloride ion sensor 10 so as to identify which chloride ion sensor 10 the information is from. It is sent to the calculation unit 50 together with the impedance information.

The wireless transmitter 3 may include a battery (not shown) that supplies power. The battery supplies at least the necessary power to the wireless transmission section 3 . Also, power may be supplied from the battery to the measurement unit 2 as necessary. By supplying the necessary power to the wireless transmission unit 3 and the measurement unit 2 from the battery, the chloride ion sensor 10 does not require wiring to the outside (for example, the wiring 22 and wiring 23 in FIG. 2), and has a simple configuration. Become. As a result, it can be installed anywhere on the concrete structure 100 .

(Third embodiment)
FIG. 4 is a schematic diagram showing a third embodiment of the chloride ion sensor of the present invention. In the third embodiment, a moisture content meter 61 is provided separately from the chloride ion sensor 10 of the first embodiment, and the moisture content meter 61 is connected to the calculation unit 50 . Moisture meter 61 acquires the moisture content of concrete structure 100 . In the first embodiment, the moisture content and the chloride ion concentration are calculated from measured values such as impedance. In contrast, in the present embodiment, by using the moisture content as the measured value, the chloride ion concentration can be calculated with improved accuracy.

The moisture meter 61 is moisture information acquisition means for acquiring the moisture content of the concrete structure 100 . This moisture meter 61 can be appropriately selected from known methods. A method of measuring moisture content based on the results, and the like can be mentioned.

(Fourth embodiment)
FIG. 9 is a schematic diagram showing a fourth embodiment of the chloride ion sensor of the present invention. In this embodiment, at least part of the wiring (conductor 8 ) between the impedance detection section 2 and the electrode 4 is composed of pattern wiring 8 a formed on the base material 6 having the electrode 4 . That is, in this embodiment, the patterned wiring electrode sheet 200 having the patterned wiring 8a and the pair of electrodes 4 on the substrate 6 is used. The pattern wiring 8a and the electrode 4 may be formed on the same surface, or the pattern wiring 8a may be formed on the surface opposite to the electrode 4 and connected through the opening of the substrate.
The pattern wiring 8a is formed by printing ink containing a conductive material between the electrodes 4 on the substrate 6 and terminals connected to the impedance detection unit 2 arranged at the end of the substrate 6, for example. a method of patterning by
Like a flexible circuit, a conductive metal is laminated on a base material 6 by vapor deposition, metal foil lamination, plating, etc., a pattern is formed by etching, electrodes 4 to be used are formed, and wiring of the impedance detection unit 2 is formed. There is a method of wiring.
If the contact resistance between the wiring pattern 8a and the electrode 4 is small, the connection between the wiring pattern 8a and the electrode 4 can be directly connected by printing. If the contact resistance is large, the wires may be connected using a conductive adhesive such as silver paste or a metal filler. The wiring pattern 8a may further have a protective portion 7 for sealing the wiring pattern, or may be wholly or partially laminated with a laminate film obtained by laminating a weather-resistant base material and an adhesive. good.
When the pattern wiring 8a is printed on the same surface as the electrodes 4, the electrodes can be formed at the ends of the wiring, and the electrodes can be partially or wholly exposed and melted by heating to be placed on the surface of the concrete structure 100. When pattern wiring 8a is printed on the opposite side of electrode 4 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, conductive adhesive, or hot-melt electrode is used. can also be joined by embedding Also in this case, the protective portion 7 may be provided on the patterned wiring 8a, and may be wholly or partially laminated with a laminated film obtained by laminating a weather-resistant base material and an adhesive.

In this embodiment, the printed wiring is preferable because it can be easily formed and is excellent in flexibility. The conductive ink used for printed wiring contains at least conductive fine particles, and if necessary, may contain other components such as a binder component and a solvent.

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

Examples of conductive fine particles include metal fine particles, carbon fine particles, and conductive oxide fine particles.
Examples of fine metal particles include single powders of metals such as gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, aluminum, tungsten, molbutene, and platinum, as well as copper-nickel alloys, silver-palladium alloys, 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 above-mentioned single metal powders or alloy powders with silver or the like can be used. Carbon fine particles include carbon black, graphite, and carbon nanotubes. Examples of conductive oxide fine particles include silver oxide, indium oxide, tin oxide, zinc oxide, and ruthenium oxide. Conductive microparticles|fine-particles can be used individually by 1 type or in combination of 2 or more types.
In this embodiment, from the viewpoint of long-term reliability of the conductive wiring, it is preferable to use carbon fine particles having excellent weather resistance such as water resistance and acid resistance.

The shape of the conductive fine particles is not particularly limited, and amorphous, aggregated, scale-like, microcrystalline, spherical, flake-like, wire-like and the like can be used as appropriate. 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 more preferably 0.5 μm or more and 30 μm or less in terms of dispersibility in conductive ink and conductivity after wiring. is more preferred.

The conductive ink preferably contains a binder component. The binder component preferably contains a resin from the viewpoint of film-forming property, adhesion after film-forming, flexibility, and the like. The resin can be appropriately selected from resins used for conductive wiring and used. Examples of such resins include acrylic resins, vinyl ether resins, polyether resins, polyester resins, polyurethane resins, epoxy resins, phenoxy resins, polycarbonate resins, polyvinyl chloride resins, polyolefin resins, and styrene block resins. Copolymer resins, polyamide-based resins, polyimide-based resins, and the like can be mentioned, and can be used singly or in combination of two or more.

The content of the conductive fine particles in the pattern wiring 8a is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, relative to the total amount of the pattern wiring 8a. Moreover, the content ratio of the binder component in the pattern wiring 8a is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, relative to the total amount of the pattern wiring 8a.
If the content of the conductive fine particles is at least the above lower limit, the conductive wiring will have excellent conductivity. Further, when the content of the binder component is at least the above lower limit, the film formability and the adhesion to the base material 6 are improved, and the conductive wiring of the electrode sheet with the conductive wiring can be imparted with flexibility. can.

The pattern wiring 8a of the electrode sheet with pattern wiring 200 is formed by, for example, preparing a conductive ink containing the conductive fine particles, the binder component, and, if necessary, a solvent or the like, and applying the conductive ink on the substrate. It can be formed by printing on and 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 gravure printing, screen printing, flexographic printing, and inkjet, depending on the composition of the conductive ink and the film thickness of the patterned wiring.

The thickness of the pattern wiring 8a of the electrode sheet with pattern wiring 200 is not particularly limited, and can be, for example, 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less, from the viewpoint of achieving both conductivity and flexibility. Moreover, the width of the conductive wiring of the printable sensor sheet is not limited, and may be set to a width that provides the required conductivity. For example, it can be 0.1 mm or more, preferably 1 mm to 100 mm. A plurality of conductive wirings may have the same thickness and width, or may have different thicknesses and widths.

<Protective portion (protective layer) of electrode sheet with patterned wiring>
The protective portion 7 of the electrode sheet with patterned wiring is a layer provided at least on the patterned wiring 8a, and suppresses the damage of the patterned wiring 8a and contact with water, oxygen, acid, alkali, etc., thereby improving long-term reliability. improve. The protective portion 7 can be formed as a protective layer by, for example, laminating a sheet similar to the sheet base material of the electrode sheet with conductive wiring.

[Chloride ion concentration measurement method]
The chloride ion concentration measurement method of this implementation is
A measuring method for measuring the chloride ion concentration in a concrete structure,
a preparation step of preparing the chloride ion sensor;
a bonding step of respectively bonding a pair of electrodes included in the chloride ion sensor to the surface of the concrete structure;
a measuring step of measuring impedance in a state in which an alternating current is passed between the pair of electrodes through a concrete body,
The adhering step includes a step of adhering the hot-melt electrode to a concrete structure by heating and melting the hot-melt electrode.

An embodiment of the corrosion detection method of the present invention will be described below with reference to FIG. FIG. 6 is a flow chart showing an example of a chloride ion concentration measuring method.
First, the chloride ion sensor 10 is prepared (S1: preparation step). Next, the pair of electrodes 1a and 1b and the surface of the concrete structure 100 are brought into electrical contact via hot-melt electrodes (S3: bonding step). Next, the impedance is measured in a state in which an alternating current is applied between the pair of electrodes through the concrete body (S4: measurement step). The obtained measurement result is sent to the calculation unit by wire or wirelessly when the chloride ion sensor 10 includes the wireless transmission unit 3 (S5: wireless transmission step), and the characteristic information DB 40 is transmitted to the calculation unit 50. The chloride ion concentration is calculated with reference to this (S6: calculation step).

In this embodiment, the bonding step includes a step of heating and melting the hot-melt electrodes of the electrodes 1a and 1b. With such a technique, even if the surface of the concrete structure 100 has unevenness, the hot-melt electrode deforms along the unevenness during melting and is strongly adhered. As a result, good electrical contact with the surface of the concrete structure 100 can be maintained for a long period of time.

Furthermore, since the chloride ion sensor using the electrode sheet 200 with pattern wiring is an electrode sheet in which the conducting wire 8 is formed on the base material in advance, it is possible to install a corrosion sensor when performing self-potential measurement over a large area and at multiple points. becomes even easier.

EXAMPLES 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 by these examples.

[Manufacture of electrode for chloride ion sensor]
<Production Example 1>
A hot-melt resin based on SIS (styrene-isoprene-styrene) elastomer and carbon filler were added to a desktop kneader equipped with a heating device, and heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The prepared hot-melt electrode was laminated on a polyimide film (Kapton 200EN: manufactured by DuPont-Toray Co., Ltd.) to a thickness of 200 μm to form an electrode having a substrate. 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 carbon filler were added to a desktop kneader equipped with a heating device, and heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN (polyethylene naphthalate) film to a thickness of 100 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 3×10 ³ Ωcm.

<Production Example 3>
A hot-melt resin based on a SEPS (styrene/ethylene/propylene/styrene) elastomer and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 200 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 2×10 ⁻¹ Ωcm.

<Production Example 4>
A hot-melt resin based on a SEPS (styrene/ethylene/propylene/styrene) elastomer and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a polyimide film to a thickness of 1000 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 2×10 ¹ Ωcm.

<Production Example 5>
A hot-melt resin based on an SEBS (styrene/ethylene/butylene/styrene) elastomer and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 300 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 6×10 ¹ Ωcm.

<Production Example 6>
A hot-melt resin based on a thermoplastic polyamide resin and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 150 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 5×10 ¹ Ωcm.

<Production Example 7>
A hot-melt resin based on a polyester-based thermoplastic resin and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 500 μm to form an electrode having a substrate. The volume resistivity of the electrode portion 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 desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 250 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 1×10 ¹ Ωcm.

<Production Example 9>
A hot-melt resin based on a polyurethane thermoplastic resin and a carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 400 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 1×10 ¹ Ωcm.

<Production Example 10>
A hot-melt resin based on polyvinyl chloride (PVC) thermoplastic resin and carbon filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. The produced hot-melt electrode was laminated on a PEN film with a thickness of 200 μm to form an electrode having a substrate. The volume resistivity of the electrode portion was 1×10 ¹ Ωcm.

<Production Example 11>
A hot-melt resin based on a SEPS (styrene/ethylene/propylene/styrene) elastomer and a silver filler were added to a desktop kneader equipped with a heating device, and the mixture was heated and stirred at 130 to 180° C. for 3 hours. After confirming that there was no unmelted elastomer, a hot-melt electrode was obtained. An electrode was obtained by laminating the produced hot-melt electrode on a PEN substrate with a thickness of 200 μm. The volume resistivity of the electrode portion was 4×10 ⁻⁴ Ωcm.

<Production example of hot-melt resin composition and sealing material sheet>
A hot-melt resin based on SIS (styrene, isoprene, styrene) elastomer is sandwiched between release films, and hot-pressed at 100°C and 100 kgf/ ^cm2 for 30 seconds using a tabletop test press manufactured by Tester Sangyo to achieve a film thickness of 200. A sealing material sheet 1 was formed by processing into a sheet of up to 300 μm.

<Production Example 12: Electrode sheet with pattern wiring>
Conductive carbon ink (carbon-based conductive paste RA FS 090: manufactured by Toyo Ink) on a polyamide film (Kapton 200EN: Toray DuPont Co., Ltd.) of 300 mm × 100 mm as shown in FIG. Printed with a space of 5 mm and thermally dried at 100 ° C. for 30 minutes, and further the hot melt electrode prepared in Example 1 was placed on a polyimide film (Kapton: manufactured by Toray DuPont Co., Ltd.) to a thickness of 200 µm so as to be 40 mm × 40 mm. Then, a sealing material sheet was placed on the ^base material so as to cover the wiring part while avoiding the electrode part. An electrode sheet with pattern wiring 200 including carbon wiring and a sealing material was obtained (FIG. 9). The volume resistivity of the electrode portion 4 was 2×10 ¹ Ωcm.

<Production Example 13: Electrode sheet with pattern wiring>
Two 10 mm wide lines are printed on a 300 mm × 100 mm polyamide film (Kapton 200EN: manufactured by Toray DuPont Co., Ltd.) with a conductive silver paste (RA FS 007: manufactured by Toyo Ink) with a space between lines of 5 mm as shown in FIG. and heat-dried at 100° C. for 30 minutes, and the hot-melt electrode prepared in Example 1 was laminated to a thickness of 200 μm on a polyimide film (Kapton: manufactured by DuPont-Toray Co., Ltd.) so as to have a size of 40 mm×40 mm. Furthermore, a sealing material sheet was placed on the base material so as to cover the wiring part while avoiding the electrode part, and hot roll lamination was performed on the release film at 150° C., 4 kgf/cm ² , 1 m/min to seal the electrode and the carbon wiring. An electrode sheet 200 with pattern wiring provided with a stopper material was obtained (FIG. 9). The volume resistivity of the electrode portion 4 was 2×10 ¹ Ωcm.
<Production Example 14: Electrode sheet with pattern wiring>
Conductive wiring 8 is copper-etched with a space of 5 mm between lines as shown in FIG. Then, a polyimide coverlay film (Nikaflex CSKE base film thickness 25 μm: manufactured by Nikkan Kogyo Co., Ltd.) is attached on the base material so as to avoid the electrode part and cover the wiring part, and the coverlay part is heated at 160 ° C. × The wiring portion was sealed by hot pressing for 90 minutes at a molding pressure of 4 MPa. Furthermore, the hot-melt electrode prepared in the example is laminated on the base material to a thickness of 300 mm so as to have a size of 40 mm × 40 mm, and the patterned wiring electrode is provided with a wiring pattern of copper wiring by electrode and etching and a sealing material by cover lay. A sheet 200 was obtained (FIG. 9). The volume resistivity of the electrode portion 4 was 2×10 ¹ Ωcm.

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

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

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

3. Composite Corrosion Resistance Test The composite corrosion test was carried out for a long period of time in accordance with the standards of the Japan Society of Automotive Engineers (JASO) M609/M610. Specifically, the sample was placed in a composite corrosion tester (BQD-2) with an angle of 70 degrees with respect to the ground. The composite corrosion conditions for the sample were as follows: First, salt spray was performed at 5% NaCl at 35°C for 2 hours, followed by 4 hours in a dry environment at 50% RH and 60°C, followed by a wet environment at 95% RH and 50°C. I stayed downstairs for two hours. This cycle was performed 200 times. After the test, the measurement sample was recovered, and the deterioration was determined by comparing the results before and after the test below.

A. Conductivity change Samples for combined corrosion test measurements are: 1. Measurement of volume resistivity, and the resistivity was also measured at the same time. After the sample was placed in the composite corrosion tester and subjected to the corrosion cycle test under the above conditions, the volume resistivity of the sample was measured in the same manner.
◎ if the volume resistivity remains below 1×10 ³ Ωcm before and after the combined corrosion test, ◯ if the volume resistivity remains below 1×10 ⁵ Ωcm before and after the combined corrosion test, otherwise x in the case of

B. Change in Adhesiveness After the corrosion cycle test was performed on the measurement sample in which the hot-melt electrode was adhered to the concrete prepared in Example 1 under the above conditions, the adhesive strength was evaluated by the same method. If 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 decrease in the adhesive strength value after the corrosion test is less than 5 N 0 in some cases, and x in other cases.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

4. Chloride ion measurement (creation of characteristic information database)
A concrete specimen used for impedance measurement was produced as a rectangular parallelepiped with a size of 200×100×100 cm as follows.
Four types of specimens containing 0.5 kg, 1 kg, 5 kg, and 10 kg of chloride per 1 m ³ of chloride were produced by casting using water, cement, and sand. Furthermore, by adjusting the moisture content of each concrete specimen to 0.5%, 1%, 5%, and 10%, a total of 16 types of concrete specimens with known chloride content and moisture content were produced. A laminate consisting of two pairs of hot-melt electrode sheets and a polyimide film having a thickness of 200 μm, a size of 4×4 cm, and an interval of 10 cm was attached to the surface of each of the concrete specimens, and heated at 200° C. Two pairs of electrodes were attached to each concrete specimen surface by crimping.
AC impedance can be measured by connecting two pairs of electrodes adhered to the same concrete specimen surface to an LCR meter via electric wires.
The frequency characteristics of the real part and the imaginary part of the AC impedance between the electrodes of each concrete specimen were measured. The frequency was swept from 0.1 Hz to 10 MHz.
The AC impedance values for each water content and contained salt concentration were plotted for each frequency to create a characteristic information database.

Next, a concrete specimen having a known water content and chloride ion content shown in Table 2 was prepared, and the electrode after the composite corrosion resistance test in Example 1 was placed on the surface of the concrete specimen in the same manner as in the creation of the above database. glued on top.
Measurement was made possible by connecting two pairs of electrodes adhered to the same concrete specimen surface to an LCR meter. The moisture content of the concrete specimen was measured in advance using a moisture meter (HI-520-2 manufactured by KETT). Quantitative evaluation of the chloride ion concentration is performed by measuring the frequency characteristics of the real part and the imaginary part of the AC impedance between the two pairs of electrodes, applying the measured water content and the AC impedance value to the characteristic information database, and using the calibration curve method. Chloride ion content was calculated. The frequency was swept from 0.1 Hz to 10 MHz. The impedance of the prepared specimen was measured, and when the chloride concentration could be quantified, it was evaluated as ◯, and otherwise as x.

<Comparative Example 1>
Using the ion gel electrode produced in Comparative Production Example 1 laminated on an aluminum substrate with a thickness of 500 μm, the following measurements were carried out. Electrical conductivity was evaluated using the AC impedance method.

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

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

3. Composite Corrosion Resistance Test The composite corrosion test was carried out for a long period of time in accordance with the standards of the Japan Society of Automotive Engineers (JASO) M609/M610. Specifically, the sample was placed in a composite corrosion tester (BQD-2) with an angle of 70 degrees with respect to the ground. The composite corrosion conditions for the sample were as follows: First, salt spray was performed at 5% NaCl at 35°C for 2 hours, followed by 4 hours in a dry environment at 50% RH and 60°C, followed by a wet environment at 95% RH and 50°C. I stayed downstairs for two hours. This cycle was performed 200 times. After the test, the measurement sample was recovered, and the deterioration was determined by comparing the results before and after the test below.

A. Conductivity change Samples for combined corrosion test measurements are: 1. It was prepared in the same manner as in the measurement of ionic conductivity, and the resistivity was also measured at the same time. After the sample was placed in the composite corrosion tester and subjected to the corrosion cycle test under the above conditions, the electrical conductivity of the sample was measured in the same manner. If the ionic conductivity is maintained at 1×10 ⁻³ S/cm or more before and after the combined corrosion test, ⊚, and the ionic conductivity is maintained at 1×10 ⁻⁵ S/cm or more before and after the combined corrosion test. 0 in some cases, and x in other cases.

B. Change in Adhesiveness After the measurement sample in which the ion gel electrode was adhered to concrete prepared in Comparative Example 1 was subjected to the corrosion cycle test under the above conditions, the adhesive strength was evaluated by the same method. If 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 decrease in the adhesive strength value after the corrosion test is less than 5 N 0 in some cases, and x in other cases.
Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)

4. Chloride ion measurement (creation of characteristic information database)
A concrete specimen used for impedance measurement was produced as a rectangular parallelepiped with a size of 200×100×100 cm as follows.
Four types of specimens containing 0.5 kg, 1 kg, 5 kg, and 10 kg of chloride per 1 m ³ of chloride were produced by casting using water, cement, and sand. Furthermore, by adjusting the moisture content of each concrete specimen to 0.5%, 1%, 5%, and 10%, a total of 16 types of concrete specimens with known chloride content and moisture content were produced. A laminate consisting of two pairs of ion gel electrode sheets and a polyimide film having a thickness of 200 μm, a size of 4×4 cm, and an interval of 10 cm was attached to the surface of each concrete specimen. Two pairs of electrodes were attached to the .
AC impedance can be measured by connecting two pairs of electrodes adhered to the same concrete specimen surface to an LCR meter via electric wires.
The frequency characteristics of the real part and the imaginary part of the AC impedance between the electrodes of each concrete specimen were measured. The frequency was swept from 0.1 Hz to 10 MHz.
The AC impedance values for each water content and contained salt concentration were plotted for each frequency to create a characteristic information database.

Next, a concrete specimen having a known water content and chloride ion content shown in Table 2 was prepared, and the electrode after the composite corrosion resistance test of Comparative Example 1 was placed on the surface of the concrete specimen in the same manner as the creation of the database. glued on top.
Measurement was made possible by connecting two pairs of electrodes adhered to the same concrete specimen surface to an LCR meter. The moisture content of the concrete specimen was measured in advance using a moisture meter (HI-520-2 manufactured by KETT). Quantitative evaluation of the chloride ion concentration is performed by measuring the frequency characteristics of the real part and the imaginary part of the AC impedance between the two pairs of electrodes, applying the measured water content and the AC impedance value to the characteristic information database, and using the calibration curve method. Chloride ion content was calculated. The frequency was swept from 0.1 Hz to 10 MHz. The impedance of the prepared specimen was measured, and when the chloride concentration could be quantified, it was evaluated as ◯, and otherwise as x.

<Examples 2 to 14>
In the same manner as in Example 1, Examples 2 to 14 were produced and measured. Table 2 shows the results.

1a, 1b electrode 2 measurement unit 3 wireless transmission unit 4 hot-melt electrode 5 conductive layer 6 base material 7 protection unit 8 conducting wire 10 chloride ion sensor 20 connected chloride ion sensors 21, 22, 23 wiring 31 sheet-like base material 40 Characteristic information database 50 Calculation unit 51 Input unit 52 Output unit 53 Storage unit 54 Calculation unit 55 Control unit 61 Moisture content meter 100 Concrete structure 101 Inner wall 200 Electrode sheet with pattern wiring

Claims (13)

A sensor for measuring the chloride ion concentration in a concrete structure,
at least a pair of electrodes spaced apart from each other on the surface of the concrete structure;
a measuring unit that measures impedance in a state in which an alternating current is passed between the at least one pair of electrodes;
The at least one pair of electrodes has a hot-melt electrode containing a hot-melt resin in which a conductive filler is dispersed,
The hot-melt resin is a thermoplastic resin selected from polyurethane resins, acrylonitrile resins, acrylic resins, polyamide resins, polyvinyl butyral resins, polyester resins, and styrene resins, and styrene thermoplastic elastomers. , a thermoplastic elastomer selected from a urethane thermoplastic elastomer, an olefin thermoplastic elastomer, a polyester thermoplastic elastomer, a polyamide thermoplastic elastomer, a fluorine thermoplastic elastomer, and a vinyl chloride thermoplastic elastomer. chloride ion sensor. 2. A chloride ion sensor according to claim 1, wherein said conductive filler is silver or conductive carbon. 3. A chloride ion sensor according to claim 1 or 2, wherein said hot melt resin comprises a thermoplastic elastomer. 4. A chloride ion sensor as claimed in any preceding claim, wherein the electrode comprises a conductive layer on the hot melt electrode. 5. A chloride ion sensor according to any one of claims 1 to 4, further comprising a substrate on said electrode. 6. A chloride ion sensor according to any one of claims 1 to 5, wherein said electrode is formed into a sheet. 7. The chloride ion sensor according to any one of claims 1 to 6, comprising a plurality of said electrodes, wherein said plurality of electrodes are arranged in a pattern on a sheet-like substrate. 8. The electrode according to claim 5 or 7 , wherein the electrode and the measuring section are connected by a conductive wiring, and at least part of the conductive wiring is a pattern wiring formed on at least one surface of the base material. Chloride ion sensor. 9. The chloride ion sensor according to any one of claims 1 to 8, further comprising a wireless transmitter that wirelessly transmits information based on the measured impedance. 10. The chloride ion sensor of Claim 9, wherein the wireless transmitter further comprises a battery for powering. A measuring method for measuring the chloride ion concentration in a concrete structure,
A preparation step of preparing the chloride ion sensor according to any one of claims 1 to 10;
a bonding step of respectively bonding at least a pair of electrodes included in the chloride ion sensor to the surface of the concrete structure;
a measuring step of measuring an impedance in a state in which an alternating current is passed through a concrete body between the at least one pair of electrodes,
The chloride ion concentration measuring method, wherein the adhering step includes a step of adhering the hot-melt electrode to a concrete structure by heating and melting the hot-melt electrode. Furthermore, a calculation step of calculating the chloride ion concentration from the measured impedance,
12. The chloride ion concentration measuring method according to claim 11, wherein said calculating step calculates the chloride ion concentration based on at least the measured impedance obtained in said impedance measuring step. The preparation step is a preparation step of preparing the chloride ion sensor according to claim 9 or 10,
13. The chloride ion concentration measuring method according to claim 11, further comprising the step of wirelessly transmitting information based on the measured impedance obtained in said impedance measuring step.

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