JP6789549B2 - Corrosion sensor and corrosion detection method for concrete structures - Google Patents

Description

The present invention relates to a corrosion sensor and a corrosion detection method for concrete structures.

Conventionally, a natural potential measuring method using a reference electrode has been used for determining corrosion of steel materials such as reinforcing bars of concrete structures. As an example of a sensor using this natural potential measurement method, for example, the sensor described in Patent Document 1 below is known.

This sensor uses a conductive material impregnated with an electrolytic solution such as calcium hydroxide to reduce the contact resistance with the surface of the concrete structure, and the natural potential of the surface of the concrete structure having reinforcing bars inside. Is being measured.

Japanese Unexamined Patent Publication No. 2013-181778

However, since the conventional sensor measures while wetting the concrete surface, the measured value changes every time the measurement is performed due to the change in the wetness, and the measurement takes time. Even in the sensor described in Patent Document 1, since the water content of the electrolytic solution evaporates, the measured value changes every time the measurement is performed, and the measurement takes time. Furthermore, since the measured value changes with each measurement, it is not suitable for long-term monitoring of corrosion conditions.

The present invention provides a corrosion sensor and a corrosion detection method capable of measuring the corrosion state of a concrete structure in a short time and monitoring over a long period of time.

The corrosion sensor of the first aspect is a corrosion sensor that detects a corrosion state of a steel material in a concrete structure, and is arranged on an electric wire electrically connected to the steel material and an ion on the surface of the concrete structure. A contact member containing a liquid, a matching electrode arranged on the surface of the concrete structure via the contact member and electrically connected to the contact member, and a voltage between the matching electrode and an electric wire are detected. It includes a voltage detection unit.

In this embodiment, since the ionic liquid can stably and long-term contact with high electrical conductivity, the corrosion state of the concrete structure can be measured in a short time and can be monitored for a long period of time.

The corrosion sensor of the second aspect is the corrosion sensor of the first aspect in which the ionic liquid is in the form of a gel.

In this embodiment, since the ionic liquid is not washed away, good contact with the surface of the concrete structure can be maintained.

The corrosion sensor of the third aspect further comprises a substrate, wherein the contact member containing the ionic liquid and the reference electrode are printed electrodes arranged on the substrate to wirelessly transmit information based on the detected voltage. It is a corrosion sensor of the first or second aspect which further comprises the radio transmission part to perform.

In this embodiment, since the contact member and the reference electrode containing the ionic liquid can be provided on the substrate in an arbitrary pattern, the contact member and the reference electrode containing the ionic liquid can be provided easily and inexpensively.

The corrosion sensor of the fourth aspect is the corrosion sensor of any one of the first to third aspects further comprising a wireless transmission unit that wirelessly transmits information based on the detected voltage.

In this embodiment, the corrosion state can be remotely monitored, and the efficiency of maintenance work can be improved.

The corrosion sensor of the fifth aspect is the corrosion sensor of the fourth aspect, further comprising a battery for supplying electric power to at least the wireless transmission unit.

In this embodiment, since it is not necessary to provide the power supply wiring to the wireless transmission unit, the corrosion sensor can be installed at an arbitrary place on the concrete structure.

The corrosion sensor of the sixth aspect is the corrosion sensor of any one of the first to fifth aspects further comprising at least a sheet in which a plurality of pairs of the reference electrode and the contact member are arranged.

In this aspect, the distribution of the corroded state of the concrete structure can be detected.

The corrosion sensor of the seventh aspect is the corrosion sensor of the sixth aspect in which the sheet has flexibility.

In this embodiment, by attaching the sheet to the curved surface or uneven surface of the concrete structure, the distribution of the corroded state of the concrete structure can be detected along the curved surface or uneven surface of the concrete structure.

The corrosion detection method of the eighth aspect is a corrosion detection method for detecting a corrosion state of a steel material in a concrete structure, which includes a wire connection step of electrically connecting a wire to the steel material and a contact member containing an ion liquid. A contact step of arranging the collation electrode on the surface of the concrete structure and electrically connecting the collation electrode to the contact member, and a voltage for detecting a voltage between the electric wire and the collation electrode. The detection step is carried out.

In this embodiment, since the ionic liquid can stably and long-term contact with high electrical conductivity, the corrosion state of the concrete structure can be measured in a short time and can be monitored for a long period of time.

The corrosion detection method of the ninth aspect is the corrosion detection method of the eighth aspect in which the wireless transmission step of wirelessly transmitting information based on the detected voltage is further carried out.

In this embodiment, the corrosion state can be remotely monitored, and the efficiency of monitoring work and maintenance work can be improved.

According to the corrosion sensor and the corrosion detection method of the present invention, the corrosion state of a concrete structure can be measured in a short time and can be monitored for a long period of time.

It is a figure which shows the installation state of the corrosion sensor in 1st Embodiment which concerns on this invention. It is sectional drawing of the main part of the corrosion sensor in 1st Embodiment which concerns on this invention. It is an enlarged view of the part III of FIG. It is sectional drawing of the main part of the corrosion sensor in 2nd Embodiment which concerns on this invention. It is sectional drawing of the main part of the corrosion sensor in 3rd Embodiment which concerns on this invention. It is a schematic diagram of the corrosion sensor in the third embodiment which concerns on this invention. It is an enlarged view of the VII part of FIG. It is a flowchart of embodiment of the corrosion detection method which concerns on this invention. It is a table which compares the detected value when there is no corrosion and when there is corrosion.

Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

"First embodiment"
Hereinafter, the first embodiment of the corrosion sensor according to the present invention will be described with reference to FIGS. 1 to 3. In this embodiment, an example of detecting corrosion of a concrete structure having reinforcing bars as a steel material is shown.

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 a sensor main body 30 and a voltage detecting unit 60, and detects a corroded state of a concrete structure 1 having a reinforcing bar 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 sensor main bodies 30.
In the present embodiment, at least each sensor main body 30 is installed in the tunnel to detect corrosion on the inner wall surface of the tunnel.

As shown in FIG. 2, which will be 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 to each other. As a simple means for connecting the electric wire 3a to the reinforcing bar 2, the electric wire 3a 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 forming a contact 20 with a conductive clip or a hook or the like 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 plurality of reinforcing bars 2 in the concrete structure 1 are arranged in a grid pattern. Each of the reinforcing bars 2 arranged in a grid pattern is bound by a numbered wire composed of another reinforcing bar 2 and a reinforcing bar at an intersection of the grids, and is electrically connected to each other.
Originally, when detecting corrosion of the surface 1a of the concrete structure 1, it is necessary to connect the electric wire 3a to the reinforcing bar 2 directly under the detection point, but when the plurality of reinforcing bars 2 are electrically connected to each other, The electric wire 3a may be connected to any of the plurality of reinforcing bars 2. If the electrical connection between the reinforcing bars 2 is insufficient only by bundling the wires, a plurality of electric wires 3a may be provided and the electric wires 3a may be connected to the reinforcing bars 2 corresponding to each sensor main body 30.

The figure shown at the bottom of FIG. 1 shows an enlarged view of a part of the plurality of sensor main bodies 30 among the plurality of sensor main bodies 30 installed in the tunnel. As shown in the enlarged view, the plurality of sensor main bodies 30 are arranged in a plane shape on the surface 1a of the concrete structure 1 along the reinforcing bars 2. In the present embodiment, the plurality of sensor main bodies 30 are arranged over a wide area of the surface 1a 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 sensor main body 30 is installed in the voltage detection unit 60, which will be described in detail later.

The voltage detection unit 60 and the processing unit 90 are communicably connected, and information based on the voltage at each detected 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, or the like 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 is output as the potential of the plate surface 40b of the reference electrode 40 with respect to the electric wire 3a, corrosion can be detected as a natural potential. Further, the processing unit 90 may output map data as shown below.
It is also possible to output the corrosion level as map data instead of the natural potential by associating the natural potential with the corrosion level.

In the processing unit 90, the relationship between each point where the sensor main body 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 voltage of each detected point with the position of the surface 1a of the concrete structure 1 from the stored relationship.
Therefore, the processing unit 90 obtains map data of the natural potential and the corrosion level of the surface 1a of the concrete structure 1 by associating the information based on the detected voltage at each point with the position of the surface 1a of the concrete structure 1. Can be created.
The created map data is output by display, printing, etc. in the processing unit 90 and presented to the operator. The map data presented to the operator shows the relationship between the natural 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 natural potential and the position or the relationship between the corrosion level and the position with 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 corroded state, or repairs or maintains the corroded portion.
The processing unit 90 used in the present embodiment may be any computer system having a CPU, a storage unit, an I / O unit, and the like, but may be composed of an electric circuit or an electronic circuit. Further, a mobile terminal such as a notebook computer, a PDA, or a tablet may be used as the processing unit 90 so that the information based on the voltage detected at an arbitrary place can be confirmed.

The structure of the corrosion sensor 10 of the present embodiment will be described.
FIG. 2 shows each sensor main body 30 that is perpendicular to the surface 1a of the concrete structure 1 and is viewed from a cross section along the reinforcing bar 2.
Each sensor body 30 includes a contact member 50 including a reference electrode 40 and an ionic liquid 51.
In the present embodiment, the electric wire 3a 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 sensor main body 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.

FIG. 3 shows in detail one of the plurality of sensor main bodies 30.
The reference electrode 40 has a plate shape including a pair of plate surfaces 40a and 40b.
The reference 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 reference electrode 40 is electrically connected to the voltage detection unit 60 by the detection pattern 3b.
The reference electrode 40 may be any reference electrode 40 as long as it is used in the natural potential measurement method, but in the present embodiment, a silver / silver chloride electrode is used. Further, as a cheaper material, silver or silver chloride containing carbon flakes may be used.

The contact member 50 is arranged so as to be interposed between the plate surface 40a of the reference electrode 40 and the surface 1a of the concrete structure 1, and makes good electrical contact between the reference electrode 40 and the surface 1a of the concrete structure 1. Maintained. In the present embodiment, the contact member 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 surface. It is in contact with 40a.

The ionic liquid 51 included in the contact member 50 will be described in detail.
The ionic liquid is generally a salt having a melting point of 100 ° C. or lower and having a low vapor pressure. Therefore, although it is a liquid having high electrical conductivity, it has a characteristic that it hardly evaporates.
The ionic liquid 51 may be any salt that exists (melts) as a liquid in the detection environment. In this embodiment, 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIM TFSI) is used as the ionic liquid 51. 1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide is present in liquid form at least at room temperature.

In the present embodiment, a gel member obtained by mixing an ionic liquid 51 with a polymer polymer (Poly (styrene-b-ethylene oxide-b-styrene): PS-PEO-PS) and gelling is used as the contact member 50. There is. Since the gel has flexibility but does not run off, if the gel member is used as the contact member 50, the ionic liquid 51 will not be washed away and the ionic liquid 51 will be good with respect to the surface 1a of the concrete structure 1. Can be contacted with. If good contact between the surface 1a of the concrete structure 1 and the ionic liquid 51 can be maintained, it is possible to maintain good electrical contact between the reference electrode 40 and the surface 1a of the concrete structure 1. ..
As a modification, the ionic liquid 51 may be absorbed by a sponge, a porous body, or a cloth and used as the contact member 50.

The corrosion sensor 10 further includes a plurality of substrates 70. A pair of a reference electrode 40 and a contact member 50 are laminated on one surface of each substrate 70. That is, each substrate 70 is provided with a sensor main body 30.
In the present embodiment, the collation electrode 40 and the contact member 50 of the gel member are printing electrodes formed on the substrate 70 by an inexpensive method such as screen printing, but mask printing, inkjet printing, dispenser printing, gravure printing, flexo printing. It may be a printing electrode formed by printing, offset printing, or the like. Further, the film is not limited to printing, and any method may be used as long as the film can be formed on the surface of the substrate 70.
The plate surface 40b of the reference electrode 40 and the detection pattern 3b are electrically connected to each other via a through hole in the substrate 70.

The voltage detection unit 60 detects the voltage between the connected electric wire 3a and the plate surface 40b of the reference electrode 40 as a natural potential. The voltage may be detected at all times or only when necessary.

Each sensor main body 30 is fixed to the surface 1a of the concrete structure 1 by applying an adhesive or a fixture.

The operation and effect of the corrosion sensor 10 of the present embodiment will be described.
In the present embodiment, since the gelled ionic liquid 51 is used as the contact member 50, even if the surface 1a of the concrete structure 1 has irregularities, the contact member 50 is deformed along the irregularities and concrete. Good electrical contact is maintained with respect to the surface 1a of the structure 1.

When the contact member is composed of a gel using a solvent such as alcohol or water, the alcohol or water evaporates, so it is necessary to go to the detection site every time detection is performed to restore the electrical contact.
In the present embodiment, since the gel using the ionic liquid 51 is used, the gel state is less likely to deteriorate with time and the gel state can be maintained for a long period of time as compared with the gel in which the solvent evaporates. Therefore, it is possible to maintain highly conductive electrical contact for a long period of time, and it is not necessary to go to the detection site every time detection is performed.
Therefore, remote detection is always possible.

Further, immediately after the surface 1a of the concrete structure 1 is brought into a wet state, it takes time for the potential to settle. In addition, the wet state changes each time the wet state is set, and the measured potential changes according to the degree of the wet state. Therefore, it is necessary to perform remeasurement many times in order to obtain a stable measurement result.
Since each sensor main body 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, and it takes time for remeasurement. Since it can be reduced, the measurement time can be shortened.

"Second embodiment"
Hereinafter, the second embodiment of the corrosion sensor according to the present invention will be described with reference to FIG.

The corrosion sensor 110 of this embodiment is basically the same as that of the first embodiment, but has a different substrate configuration.

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 substrate 170.
As shown in FIG. 4, a plurality of sensor main bodies 30 are arranged on one surface 170a of the substrate 170. Each sensor body 30 includes a pair of laminated reference electrodes 40 and contact members 50.
In this embodiment, in order to make the substrate 170 flexible, a sheet formed of polyimide is used for the substrate 170. As a modification, flexibility can also be provided by using a sheet formed of a resin such as PET or PEN for the substrate 170.

Similar to the first embodiment, the reference electrode 40 and the contact member 50 are formed by an inexpensive method such as screen printing on the substrate 170, but any method can be used as long as the film can be formed on the surface of the substrate 170. You may.

Each sensor main body 30 is fixed to the surface 1a of the concrete structure 1.
Specifically, the substrate 170 is adhered to the surface 1a of the concrete structure 1 with an adhesive between the arranged sensor main bodies 30.
As a modification, the substrate 170 is composed of a thin sheet, and the substrate 170 is fixed to the surface 1a of the concrete structure 1 between the arranged sensor main bodies 30 with pins, staples, or the like. May be fixed to the concrete structure 1.

Further actions and effects of the corrosion sensor 110 of the present embodiment will be described.
In the present embodiment, since the substrate 170 is made flexible, for example, when the corrosion sensor 110 is installed on the inner wall surface of the tunnel, if the substrate 170 is fixed to the inner wall of the tunnel, the curved surface or the uneven surface of the inner wall of the tunnel is formed. The substrate 170 is deformed along the line. Therefore, a plurality of sensor main bodies 30 can be installed along the curved surface or the uneven surface of the inner wall of the tunnel.

"Third embodiment"
Hereinafter, the third embodiment of the corrosion sensor according to the present invention will be described with reference to FIGS. 5 to 7.

The corrosion sensor 210 of the present embodiment is basically the same as that of the second embodiment, except that it includes a wireless transmitter.

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 sensor main bodies 30 including a contact member 50 including a reference electrode 40 and an ionic liquid 51, and a plurality of voltage detection units 80. In the present embodiment, as shown in FIG. 5, the corresponding voltage detection unit 80 is arranged next to each sensor main body 30.

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

The corrosion sensor 210 is fixed to the concrete structure 1 with an adhesive.
As a modification, the substrate 270 is made of a thin sheet, and the substrate 270 is fixed to the surface 1a of the concrete structure 1 with pins, staples, or the like at a position avoiding the sensor main body 30 and the voltage detection unit 80 to corrode. The sensor 210 may be fixed to the concrete structure 1.

The substrate 270 includes a conductive main pattern 203D that provides a uniform potential throughout the substrate 270.
In the present embodiment, the main pattern 203D is provided as an intermediate layer of the substrate 270, but it may be provided on the front surface 270a of the substrate 270 or on the back surface 270b of the substrate.
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 the potential of the electric wire 203a can be distributed over the entire substrate 270.

The structure of each voltage detection unit 80 will be described with reference to FIG.
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 reference 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 substrate 270, but as a modification, it may be provided only on the surface 270a of the substrate 270. Further, in the present embodiment, a part of the sub pattern 203d is provided inside the substrate 270, but as a modification, the main pattern 203D is provided on the surface 270a of the substrate 270, and the sub pattern 203d is provided together with the main pattern 203D. It may be provided only on the surface 270a of the substrate 270. In this case, since it is not necessary to provide the pattern inside the substrate 270, the pattern processing process is simplified.

The voltage detection unit 260 detects the voltage between the connected electric wire 203a and the plate surface 40b of the reference electrode 40. The voltage may be detected at all times 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 the signal corresponding to the voltage detected by the voltage detection unit 260 and converts it into the signal Sd corresponding to the voltage. The converted signal Sd is transmitted to the processing unit 290 by the wireless transmission unit 81. The transmitted signal Sd 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 waves, and electromagnetic waves.
At this time, each wireless transmission unit 81 detects the identification information of the voltage detection unit 80 provided with the radio transmission unit 81 so that the information based on the detected voltage can be identified from which voltage detection unit 80. It is sent to the processing unit 290 together with the information based on the voltage.

The battery 82 supplies the necessary power to the wireless transmitter 81. If necessary, the battery 82 may also supply power to the voltage detection unit 260. If the battery 82 supplies the necessary power to the wireless transmission unit 81 and the voltage detection unit 260, it is not necessary to provide the power supply wiring. Therefore, the corrosion sensor 210 can be placed at an arbitrary location on the surface 1a of the concrete structure 1. Can be installed.
In the present embodiment, each voltage detection unit 80 is provided with a battery 82, but as a modification, each voltage detection unit 80 is not provided with a battery 82, but a battery is provided for each of several voltage detection units 80, and one battery is provided. May supply power to some voltage sensing units 80.
If there is no difficulty in laying the power supply wiring, 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 the information based on the detected voltage sent from each voltage detection unit 80 and the identification information of the voltage detection unit 80, and provides the information to the operator.
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 associate the information based on the detected voltage with the position of the surface 1a of the concrete structure 1 by using the identification information of the voltage detection unit 80.
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 can obtain the surface 1a of the concrete structure 1 from the information sent from each voltage detection unit 80. Map data of natural potential or corrosion level can be created.
The created map data is output by the processing unit 290 by display, printing, or the like, and is presented to the operator. The map data presented to the operator is presented by contour lines or color maps showing the relationship between the natural 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 corroded state, or repairs or maintains the corroded portion.
In the present embodiment, a mobile terminal such as a notebook computer, a PDA, or a tablet is used as the processing unit 290 so that the information based on the voltage detected at an arbitrary place can be confirmed.

Further actions and effects of the corrosion sensor 210 of the present embodiment will be described.
First, in the present embodiment, since a plurality of pairs of one sensor main body 30 and one voltage detection unit 80 are arranged in a grid pattern over the entire substrate 270, the corrosion sensor 210 is a grid on the surface 1a of the concrete structure 1. The corrosion state at each point of the shape can be detected. Therefore, the two-dimensional distribution of the corroded state can be measured along the surface 1a of the concrete structure 1.
Further, in the present embodiment, by using the ionic liquid 51, the corroded 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 acquire information on the corrosion state wirelessly, as long as the processing unit 290 is close to the operator, the operator does not have to go to the detection site for a long period of time, and the operator can perform it at any place on the surface 1a of the concrete structure 1. The natural potential or corrosion level can be monitored at any location, and the map data of the natural potential or corrosion level can be monitored at any location.
Further, if the processing unit 290 is configured by a mobile terminal, the processing unit 290 can check the corroded part and go to the detection site determined to be the corroded part, so that the work efficiency of repairing and maintaining the corroded part is improved. ..

Further, the corrosion sensor 210 and the processing unit 290 of the present embodiment are wireless. Further, the substrate 270 is composed of a flexible sheet.
Therefore, for example, when installing the corrosion sensor 210 on the inner wall surface of the tunnel, simply bring only the corrosion sensor 210 as shown in FIG. 6 into the tunnel and attach it to the inner wall of the tunnel with an adhesive, a pin, or a staple. Since the installation of the 210 is completed, the installation of the corrosion sensor 210 is easy.

"Corrosion detection method"
Hereinafter, embodiments of the corrosion detection method of the present invention will be described with reference to FIG.
In this embodiment, each step shown in FIG. 8 is carried out. This embodiment is carried out by applying any of the corrosion sensors 10, 110 or 210 to the concrete structure 1 having the reinforcing bars 2.

First, the electric wire is electrically connected to the reinforcing bar 2 (S1: electric wire connection step). Next, the plate surface 40a of the reference electrode 40 and the surface 1a of the concrete structure 1 are electrically brought into contact with each other via the ionic liquid 51 (S2: contact step). Subsequently, the voltage between the electric wire and the plate surface 40b of the reference electrode 40 is detected by the voltage detection unit (S3: voltage detection step).
The detected voltage may be output as it is by the voltage detection unit by display, printing, etc. and presented to the operator, but in the present embodiment, further, a step of wirelessly transmitting information based on the detected voltage to the processing unit. (S4: wireless transmission step). 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 contact step S2 is carried out by using a plurality of sensor main bodies 30 including the contact member 50 including the reference electrode 40 and the ionic liquid 51, but as a modification, instead of the sensor main body 30 The ionic liquid 51 may be provided on the surface 1a of the concrete structure 1 to carry out the contact step S2.
That is, the ionic liquid 51 may be applied or sprayed on the surface 1a of the concrete structure 1, and the plate surface 40a of the reference electrode 40 may be electrically brought into contact with the surface 1a of the concrete structure 1 via the ionic liquid 51. .. Further, an adhesive material may be applied or sprayed on the surface 1a of the concrete structure 1 together with the ionic liquid 51 to fix the plate surface 40a of the reference electrode 40.
Further, the ionic liquid 51 is applied or sprayed on the plate surface 40a of the reference electrode 40 with respect to the corrosion sensor 10, 110 or 210 not provided with the ionic liquid 51, and the plate surface 40a of the reference electrode 40 is coated with the ionic liquid 51. The surface 1a of the concrete structure 1 may be electrically contacted with the surface 1a.

"Corrosion detection result"
FIG. 9 shows the detection result of the corrosion detected by this embodiment.
The table on the left shows the detected values of the natural potentials at three points (A, B, C) on the surface 1a of the concrete structure 1 measured in a state where the reinforcing bar 2 directly below is not corroded.
The table on the right shows the detected values of the natural potential when the reinforcing bar 2 directly under the same three points (A, B, C) is corroded. The detected value [mV] in the table is the average value ± standard deviation at the detection time of 60 seconds for each of the points A, B, and C. The reproducibility was also confirmed by measuring each point twice.
From this result, there is a remarkable difference between the detected value when there is no corrosion and the detected value when there is corrosion. Therefore, it can be seen that the presence or absence of corrosion of the reinforcing bar 2 can be determined by this embodiment.
The total average of the detected values in each table of FIG. 9 indicates the average value ± standard deviation. The detection time is 60 seconds at each point of each time, and the detection order is A (1st time) → B (1st time) → C (1st time) → A (2nd time) → B (2nd time) → C (2 times). The second time).

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the above embodiments, and design changes and the like within a range not deviating from the gist of the present invention are also included.

In the embodiment of the corrosion detection method, the contact step S2 is carried out after the electric wire connecting step S1, but the electric wire connecting step S1 may be carried out after the contact step S2.

The corrosion sensor of the present embodiment uses the gel member as the contact member 50, but if the contact member 50 can be formed by the ionic liquid 51 itself, the ionic liquid 51 itself may be used as the contact member 50.
Further, the contact member 50 containing the ionic liquid 51 is formed by providing irregularities and grooves on the contact surface of the contact member 50 with the surface 1a of the concrete structure 1 and impregnating the concaves and recesses of the irregularities and grooves with the ionic liquid 51. You may.

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

1: Concrete structure 1a: Surface 2: Reinforcing bar 3a: Electric wire 3b: Detection pattern 5: Corrosion detection system 10: Corrosion sensor 20: Contact 30: Sensor body 40: Collation electrode 40a: Plate surface 40b: Plate surface 50: Contact Member 51: Ion liquid 60: Voltage detection unit 70: Substrate 80: Voltage detection unit 81: Wireless transmission unit 82: Battery 90: Processing unit 105: Corrosion detection system 110: Corrosion sensor 170: Substrate 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: Substrate 270a: Front surface 270b: Back surface 290: Processing unit Sd: Signal

Claims (8)

A corrosion sensor that detects the corrosion state of steel materials in concrete structures.
An electric wire electrically connected to the steel material and
A contact member arranged on the surface of the concrete structure and containing an ionic liquid,
A reference electrode arranged on the surface of the concrete structure via the contact member and electrically connected to the contact member,
A voltage detection unit that detects the voltage between the reference electrode and the electric wire,
A corrosion sensor comprising a sheet in which a plurality of pairs of the reference electrode and the contact member are arranged . The corrosion sensor according to claim 1, wherein the ionic liquid is in the form of a gel. The corrosion sensor further comprises a substrate and
The corrosion sensor according to claim 1 or 2, wherein the contact member and the reference electrode are printed electrodes arranged on the substrate. The corrosion sensor according to any one of claims 1 to 3, further comprising a wireless transmission unit that wirelessly transmits information based on the detected voltage. The corrosion sensor according to claim 4, further comprising a battery for supplying electric power to at least the wireless transmitter. The corrosion sensor according to claim 5 , wherein the sheet is flexible. It is a corrosion detection method that detects the corrosion state of steel materials in concrete structures.
An electric wire connection process for electrically connecting an electric wire to the steel material,
A contact step of electrically contacting the reference electrode and the surface of the concrete structure in a sheet in which a plurality of pairs of a reference electrode and a contact member containing an ionic liquid are arranged via the ionic liquid .
A corrosion detection method for carrying out a voltage detection step of detecting a voltage between the electric wire and the reference electrode. The corrosion detection method according to claim 7 , further performing a wireless transmission step of wirelessly transmitting information based on the detected voltage.

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