JP2020008308A - Corrosion sensor and method for detecting corrosion - Google Patents

Abstract

To provide a method for detecting, by a non-destructive and easy way, a corrosive state in a target space unrecognizable from the outside, and a sensor suitable for the method.SOLUTION: A corrosion sensor 2 is a corrosion sensor for detecting a progress of a corrosive environment in a target space unrecognizable from the outside. The corrosion sensor includes: a metal-adaptive FR tag 4 having a first surface and a second surface facing each other; and a corrosive metal member 5 covering the first surface of the metal-adaptive RF tag, the second surface of the metal-adaptive RF tag being buried to be capable of facing a reader or a reader/writer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a corrosion detection sensor and a corrosion detection method. More specifically, the present invention relates to a method for detecting the progress of a corrosive environment in a space that is not visible from the outside or an object placed in the space, a method for detecting corrosion, and a sensor suitable for using this method.

  Corrosion of the reinforcing bars contained in the concrete structure has a great effect on the durability of the concrete structure. For this reason, it is important to grasp the state of the corrosive environment of the concrete structure in advance, and to grasp the corrosion of the rebar at an early stage.

  The steel material in the concrete structure has a passivation film formed on the surface of the steel material because the concrete maintains an alkaline environment, and is protected from corrosion by the film. However, for example, when corrosion factors such as carbon dioxide and chloride ions in the air enter the concrete, the passive film is destroyed, and the water and oxygen in the concrete start corrosion of the steel material.

  When the steel material of the concrete structure corrodes, the steel material expands in volume, and the expansion pressure causes cracks in the concrete surface. When such cracks occur, corrosion factors are more likely to penetrate through the cracks, and the progress of the corrosive environment is accelerated. In other words, in a situation where cracks can be confirmed on the concrete surface, it is assumed that the concrete structure and the rebar existing inside the concrete structure have been considerably deteriorated.

  That is, there is a situation in which it is desired to grasp the progress of the corrosion of the concrete structure at a stage before the corrosion environment inside the structure or at the time when the corrosion of the reinforcing steel progresses to the extent that the change in the state of the concrete surface can be visually confirmed. If it is confirmed that the corrosive environment of the concrete structure is progressing, for example, a maintenance operation of covering the concrete surface with a predetermined material can be performed in order to prevent the corrosive factor from entering the inside.

  BACKGROUND ART Conventionally, there has been known a method of detecting a corrosion state inside a concrete structure by measuring polarization resistance (for example, see Patent Document 1).

JP 2013-242163 A

  In order to detect the corrosion state of a reinforcing bar included in a concrete structure by using the polarization resistance technique, it is necessary to extract a reinforcing bar as an object. That is, it is necessary to destroy (slightly destroy) a part of the concrete structure. For this reason, a large amount of work is required to detect the internal corrosion state, and the inspection work requires time.

  In addition, it may be necessary to detect the corrosion state of structures that are not visible inside, not only concrete structures, and depending on the location of such structures, the work for destruction may be difficult in the first place. obtain.

  In view of the above problems, an object of the present invention is to provide a method for detecting a corrosive environment or a corrosive state in a target space that cannot be visually recognized from the outside by a nondestructive and simple method, and a sensor suitable for using the method. And

Corrosion detection sensor according to the present invention,
A corrosion detection sensor for detecting the progress of a corrosive environment in a target space that cannot be visually recognized from the outside,
A metal-compatible RF tag having a first surface and a second surface facing each other,
A corrosive metal member formed on the first surface of the metal-compatible RF tag to substantially cover the first surface,
The first feature is that the second surface of the metal-compatible RF tag is embedded and arranged so as to face a reader or a reader / writer.

  This corrosion detection sensor is used for detecting the progress of a corrosive environment in a target space that cannot be visually recognized from the outside by simulating a corrosive metal member as a target. A corrosion detection sensor is arranged in the target space, and a radio signal is received by a reader or reader / writer capable of communicating with the RF tag for metal, whereby the progress of the corrosive environment is detected.

  In this specification, a “reader” refers to a device having a function of reading a radio signal transmitted from a metal-compatible RF tag and not having a function of writing information to the metal-compatible RF tag, and a “reader / writer”. "" Refers to a device having a function of reading a radio signal transmitted from a metal-compatible RF tag and a function of writing information to the metal-compatible RF tag. Hereinafter, in order to avoid complication, the term “reader / writer / writer” may be abbreviated as “reader / writer or the like”.

  In the present specification, the “metal-compatible RF tag” means that when a metal material is present at a position near the opposite side of the metal-compatible RF tag from the reader / writer, the metal-compatible RF tag and the reader / writer, etc. While communication is formed, when a metal material does not exist at the position, it refers to an RF tag having a property that a signal intensity transmitted to a reader / writer or the like is extremely reduced.

  For the sake of simplicity, a case where the corrosive metal member is formed so as to completely cover the first surface of the metal-compatible RF tag will be described as an example. If the corrosive environment has not progressed to the vicinity of the placement position of the metal-compatible RF tag in the target space, if a reader / writer or the like is placed on the second surface side of the metal-compatible RF tag, Since the metal material contained in the corrosive metal member to be covered exists at a position opposite to the reader / writer or the like, a communication environment is formed between the reader / writer or the like and the metal-compatible RF tag. On the other hand, when the corrosive environment has progressed to some extent in the target space, the corrosive metal member that covers the first surface of the RF tag also progresses in corrosion. At this time, the metal component disappears because the corrosive metal member changes to a metal compound. As a result, a communication environment is not formed between the reader / writer and the metal-compatible RF tag, or the intensity of the received radio signal is reduced.

  That is, the presence or absence or the degree of the progress of the corrosive environment in the target space can be detected based on the presence or absence or intensity of the radio signal received by the reader / writer or the like.

  The above-described corrosion detection sensor has a configuration in which a corrosive metal member is arranged on one surface of a metal-compatible RF tag, so that the size can be reduced. For this reason, the corrosion detection sensor can be arranged at a desired position in the target space. For example, by disposing the corrosion detection sensor at a position near the outer surface of the target space, it is possible to detect the degree of progress of the corrosive environment at a stage before the corrosive environment proceeds to a deep position in the target space. In addition, by arranging multiple corrosion detection sensors at different positions in the depth direction with respect to the outer surface in the target space, the difference in the intensity of the radio signal from each corrosion detection sensor causes You can know the situation in more detail.

Further, the corrosion detection sensor according to the present invention,
A corrosion detection sensor that detects the progress of corrosion on a metal object, which is arranged in a state invisible from the outside by being covered by the nonmetallic coating,
A metal-compatible RF tag having a first surface and a second surface facing each other,
The first surface of the metal-compatible RF tag is brought into contact with the object, and the second surface of the metal-compatible RF tag is embedded and arranged so as to be able to face a reader or a reader / writer. The second feature.

  When the corrosive environment has progressed to some extent in the space where the metal object is arranged, the corrosion also progresses on the metal object itself formed on the first surface of the metal-compatible RF tag. Then, some or all of the metal components contained in the object disappear. As a result, a communication environment is not formed between the reader / writer and the metal-compatible RF tag, or the intensity of the received radio signal is reduced. Therefore, as in the case of the corrosion detection sensor having the first characteristic configuration, it is possible to detect the start of corrosion of the object itself and its progress, or the degree thereof, by the presence or absence or intensity of a radio signal received by a reader / writer or the like. it can.

  The object may be, for example, a reinforcing bar in reinforced concrete.

  The corrosion detection sensor may include a failure detection metal member that exhibits corrosion resistance and is adhered to a part of the metal-compatible RF tag on the first surface.

  As described above, when the corrosion proceeds on the corrosive metal member or the metal object existing on the first surface of the metal-compatible RF tag, and the remaining amount of the metal material decreases, it is received by a reader / writer or the like. The strength of the radio signal decreases. Therefore, when the corrosive metal member or the target object is extremely corroded, a radio signal may not be received at all by a reader / writer or the like. In such a case, it is determined whether the reader / writer or the like and / or the metal-compatible RF tag is out of order, or whether the corrosion has progressed to such an extent that the corrosive metal member or the object is completely lost. Can not.

  On the other hand, as described above, by adhering the failure detecting metal member to the metal-compatible RF tag in advance, the corrosion has progressed to such an extent that the corrosive metal member or the metal object is lost. Also in this case, if the reader / writer or the like and / or the metal-compatible RF tag has not failed due to the presence of the failure detection metal member, the reader / writer or the like has a predetermined strength (hereinafter referred to as “minimum reference strength”). ) Can be received. Therefore, by comparing the intensity of the radio signal actually received by the reader / writer or the like with the minimum reference intensity, the state of corrosion of the target space or the target object can be estimated. In addition, when the radio signal is not actually received by the reader / writer or the like, it is possible to recognize that the reader / writer or the like and / or the metal-compatible RF tag is out of order.

  In the corrosion detection sensor according to the first characteristic configuration, it is preferable that the corrosive metal member is formed so as to cover an area of 80% or more and 100% or less of the first surface of the metal-compatible RF tag. . In this case, the metal member for failure detection may be formed on the first surface of the metal-compatible RF tag on which the corrosive metal member is not formed. In addition, a metal member for failure detection is formed on a part of the first surface of the metal-compatible RF tag, and a corrosive metal member is formed so as to cover both the metal member for failure detection and the first surface of the metal-compatible RF tag. It may be formed.

  When the reader / writer or the like is arranged outside the target space (or the space where the target object is covered), the corrosion detection sensor preferably directs the second surface of the metal-compatible RF tag to the target surface. It is embedded and arranged substantially facing the outer surface of the space. Since the radio signal has directivity, by arranging in such a direction, the radio signal can be correctly received by a reader / writer or the like when the progress of the corrosive environment is not so advanced. Note that the phrase “substantially opposed” between the first surface of the RF tag and the outer surface of the target space means that the absolute value of the angle between the first surface and the outer surface is 45 ° or less. It does not matter. The absolute value of the angle is more preferably 30 ° or less, and further preferably 15 ° or less.

  When the position to be detected is sufficiently deep in the depth direction, a reader / writer or the like may be embedded together with the metal-compatible RF tag. In this case, the corrosion detection sensor and the metal-compatible RF tag are preferably embedded with the second surface of the metal-compatible RF tag substantially opposed to the outer surface of the metal-compatible RF tag. Placed.

The present invention is a method for detecting the progress of a corrosive environment in a target space that cannot be visually recognized from the outside,
A plate-shaped metal-compatible RF tag having a first surface and a second surface facing each other, and a corrosive metal formed on the first surface of the metal-compatible RF tag so as to substantially cover the first surface (A) disposing a corrosion detection sensor comprising a member in the target space;
(B) arranging a reader or reader / writer at a position away from the metal-compatible RF tag on the second surface side, and a radio signal transmitted from the metal-compatible RF tag by the reader or reader / writer Receiving step (c).

Further, the present invention is a method for detecting the progress of corrosion on a metal object, which is disposed in a state invisible from the outside by being covered by a nonmetallic coating,
A corrosion detection sensor comprising a plate-shaped metal-compatible RF tag having a first surface and a second surface facing each other is disposed in a state where the first surface of the metal-compatible RF tag is in contact with the object. (A),
(B) arranging a reader or reader / writer at a position away from the metal-compatible RF tag on the second surface side, and a radio signal transmitted from the metal-compatible RF tag by the reader or reader / writer Receiving step (c).

  In the step (a), the corrosion detection sensor may be arranged so that the object surrounds the periphery of the metal-compatible RF tag when viewed from a direction perpendicular to the first surface. Absent. Thus, the presence of the metal-compatible RF tag prevents the corrosion factor from hindering the metal object from advancing, and improves the accuracy of detecting the progress of corrosion on the object. .

  The step (c) may include a step of detecting the progress of corrosion based on the presence or absence of the radio signal from the metal-compatible RF tag or the intensity of the radio signal from the metal-compatible RF tag. Further, the corrosion detection method includes a step (d) of determining that corrosion is progressing when the intensity of the radio signal read in the step (c) is lower than a predetermined threshold. It does not matter.

  When the reader / writer or the like is configured to detect only the presence or absence of a radio signal from a metal-compatible RF tag, the arrangement position of the reader / writer or the like is adjusted, and more specifically, the separation distance from the metal-compatible RF tag. By checking the presence or absence of a radio signal while adjusting the frequency, it is possible to detect the progress of corrosion based on the position of the reader / writer or the like from which the radio signal has been received.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to detect the corrosion state in the target space which cannot be visually recognized from the outside by a nondestructive and simple method.

1 is a drawing schematically showing an aspect of a first embodiment of a corrosion (environment) detection method according to the present invention. It is a schematic diagram for explaining the structure of the corrosion detection sensor of the first embodiment. It is a schematic drawing for demonstrating the structure of the sensor for corrosion detection when a corrosive environment is progressing. FIG. 3B is a schematic drawing for explaining a structure of a corrosion detection sensor when a corrosive environment is further progressing from the state of FIG. 3A. It is an example of a functional block diagram of a reader / writer. FIG. 2 is an example of a functional block diagram of a reader / writer capable of communicating with a server. It is a schematic diagram for explaining another structure of the sensor for corrosion detection of the first embodiment. FIG. 3 is a plan view schematically showing one surface of a metal-compatible RF tag. FIG. 4 is another plan view schematically showing one surface of the metal-compatible RF tag. FIG. 9 is still another plan view schematically showing one surface of the metal-compatible RF tag. It is a figure showing typically the mode in which the sensor for corrosion detection and the reader / writer are embedded. It is a figure showing typically the mode of the second embodiment of the corrosion detection method concerning the present invention. It is a schematic diagram for explaining the structure of the sensor for corrosion detection of the second embodiment. It is a schematic diagram for explaining the structure of the sensor for corrosion detection of the second embodiment. It is a schematic drawing for demonstrating the aspect of the sensor for corrosion detection when corrosion is progressing. It is another schematic drawing for demonstrating the structure of the sensor for corrosion detection of 2nd embodiment. It is a figure showing typically the mode in which the sensor for corrosion detection and the reader / writer are embedded. It is a figure showing typically the mode in which the sensor for corrosion detection and the reader / writer are embedded. It is a figure which shows typically the structure of the sensor for corrosion detection provided with the protection sheet as a protection member. It is drawing which shows typically the structure of the sensor for corrosion detection provided with the mortar as a protection member.

  Hereinafter, embodiments of a corrosion detection sensor and a corrosion detection method of the present invention will be described with reference to the drawings as appropriate. In the following drawings, some parts may be exaggerated for convenience of explanation, and the actual dimensional ratio does not always match the dimensional ratio in the drawings.

[First embodiment]
FIG. 1 is a drawing schematically showing an aspect of the first embodiment of the corrosion detection method according to the present invention. In the example shown in FIG. 1, it is assumed that the target space for detecting the progress of corrosion (environment) is inside the concrete structure 10.

  As shown in FIG. 1, a corrosion detection sensor 2 is disposed inside a concrete structure 10 (inside a concrete member 11). The corrosion detection sensor 2 may be embedded in the concrete member 11 in advance at the time of manufacturing the concrete structure 10, or a part of the existing concrete structure 10 may be scraped off and extracted. After embedding 2, it may be back-filled with a protective member made of a nonmetallic material. Thus, the step of disposing the corrosion detecting sensor 2 in the target space corresponds to the step (a).

  FIG. 2 is a schematic drawing for explaining the structure of the corrosion detection sensor 2 and corresponds to a partially enlarged view of FIG. The corrosion detection sensor 2 includes a plate-shaped metal-compatible RF tag 4 having a first surface 4a and a second surface 4b facing each other, and a corrosive formed so as to cover the first surface 4a of the metal-compatible RF tag 4. And a metal member 5.

  The metal-compatible RF tag 4 has a built-in inductive antenna (not shown) and performs communication at a radio frequency in a predetermined frequency band. When a metal material is present at a position opposite to the signal transmission source (here, the reader / writer 3), the metal-compatible RF tag 4 receives the radio signal W1 from the reader / writer 3 and receives the radio signal (response signal). This is an RF tag that can transmit W2. As an example, the metal-compatible RF tag 4 is a plate-type RF tag having a resonance frequency of 920 MHz, dimensions of the first surface 4a and the second surface 4b of 25 mm × 9 mm, and a thickness of 3 mm. However, in the present invention, the metal-compatible RF tag 4 has a communication frequency band and dimensions as long as a communication environment is formed with the reader / writer 3 when a metal material exists on the side opposite to the reader / writer 3. , And the shape are arbitrary.

  The corrosive metal member 5 is a metal material having low corrosion resistance, and examples thereof include materials such as iron, zinc, and aluminum. The shape of the corrosive metal member 5 is preferably a foil shape, and can be formed by a foil plate, vapor deposition, or plating. However, in the present invention, the shape of the corrosive metal member 5 is arbitrary. The corrosive metal member 5 is adhered on the first surface 4a of the metal-compatible RF tag 4 via, for example, an adhesive. The thickness of the corrosive metal member 5 is, for example, 10 μm or more from the viewpoint of strength and 500 μm or less from the viewpoint of early detection.

  In the example shown in FIG. 2, the corrosion detection sensor 2 is arranged such that the second surface 4b of the metal-compatible RF tag is substantially opposed to the outer surface 10a of the concrete structure 10.

  When detecting the progress of the corrosive environment in the concrete structure 10, the worker attaches the reader / writer 3, which can wirelessly communicate with the corrosion detection sensor 2 embedded in the concrete structure 10, to the concrete. Bring it to the structure 10 site. Then, the reader / writer 3 is arranged near the region where the corrosion detection sensor 2 is embedded (corresponding to the step (b)). More specifically, the reader / writer 3 is disposed at a position away from the metal-compatible RF tag 4 toward the second surface 4b. Note that the reader / writer 3 may be held by an operator holding it by hand, or may be held by a holding member (not shown).

  Then, a radio signal W1 of a predetermined frequency is emitted from the reader / writer 3 toward the corrosion detection sensor 2, and a radio signal W2 transmitted from the corrosion detection sensor 2 (more specifically, a metal-compatible RF tag 4) is received. (Corresponding to step (c)).

  The reader / writer 3 may be a dedicated device or a general-purpose device such as a smartphone or a tablet PC in which a dedicated application program capable of transmitting the radio signal W1 and receiving the radio signal W2 is installed. . In this embodiment, the case where the “reader / writer 3” is used will be described as an example. However, any device that can communicate with at least the corrosion detection sensor 2 may be used. It may be a so-called "reader" which does not have the writing function of the above.

  As shown in FIG. 2, when the corrosion detection sensor 2 includes the corrosive metal member 5, the surface of the metal-compatible RF tag 4 on the opposite side to the reader / writer 3 (first A metal member exists on the surface 4a) side. Therefore, a communication environment is established between the reader / writer 3 and the metal-compatible RF tag 4, and the reader / writer 3 receives the radio signal W2.

  On the other hand, as shown in FIG. 3A, when the corrosive environment is progressing in the concrete structure 10 (in the concrete member 11), a part of the corrosive metal member 5 becomes a metal compound such as oxide or chloride. 5a. In this case, the amount of the metal member located on the surface (first surface 4a) of the metal-compatible RF tag 4 opposite to the reader / writer 3 decreases, and the intensity of the radio signal W2 received by the reader / writer 3 decreases. . As shown in FIG. 3B, when the corrosive environment further advances, the reader / writer 3 cannot receive the radio signal W2 at all.

  That is, when the intensity of the radio signal W2 received by the reader / writer 3 is low, it can be detected that the corrosive environment is progressing in the concrete structure 10. For example, a threshold value indicating that the concrete structure 10 should be repaired is set in advance, and if the intensity of the radio signal W2 received by the reader / writer 3 is lower than the threshold value, the concrete structure 10 It may be determined that the repair time has arrived (corresponding to step (d)).

  The reader / writer 3 has a function of displaying the degree of corrosion in the concrete structure 10 using, for example, a predetermined index (such as A / B / C) according to the intensity of the radio signal W2. I do not care. FIG. 4 is an example of a functional block diagram of the reader / writer 3. The reader / writer 3 includes a storage unit 31, a determination processing unit 32, a display output unit 33, and a communication unit 34. The storage unit 31 is configured by a storage medium such as a flash memory and a hard disk. The determination processing unit 32 is a processing unit that performs arithmetic processing based on the acquired information, and is configured by dedicated hardware or software. The display output unit 33 is a functional unit that performs a predetermined display calculation process and displays the processed content on a monitor (not shown). The communication unit 34 is an interface for performing wireless communication.

  The storage unit 31 stores information (hereinafter, “reference information”) corresponding to the correlation between the intensity of the radio wave signal W2 received from the corrosion detection sensor 2 and the progress of the corrosive environment in the concrete structure 10 in advance. Is stored. When the communication unit 34 receives the radio wave signal W2 from the corrosion detection sensor 2, the determination processing unit 32 reads out the reference information stored in the storage unit 31, and reads the reference information and the actually received radio wave signal W2. The progress of the corrosive environment in the concrete structure 10 is estimated based on the strength of the concrete structure 10. The display output unit 33 displays information based on the determination result on a monitor (not shown) provided in the reader / writer 3. Thus, the worker can recognize the degree of progress of the corrosive environment in the concrete structure 10 only by checking the information on the monitor provided in the reader / writer 3. When the reader / writer 3 is a general-purpose device such as a smartphone or a tablet PC, the monitor may correspond to a display unit of the general-purpose device, and the information may be displayed through a dedicated application.

  Further, the reference information may be obtained from a predetermined server 40 and updated in the storage unit 31 (see FIG. 5). The radio signal W2 can include identification information (i1) previously given to the corrosion detection sensor 2. When the communication unit 34 receives the radio signal W2 including the identification information i1 from the corrosion detection sensor 2, the communication unit 34 downloads the reference information on the concrete structure 10 corresponding to the identification information i1 from the server 40 and stores the reference information in the storage unit 31. (Temporarily). Then, the determination processing unit 32 estimates the progress of the corrosive environment in the concrete structure 10 based on the intensity of the radio signal W2 actually received and the reference information downloaded from the server 40.

  According to this method, the concrete environment in the concrete structure 10 is determined on the basis of the reference information in consideration of the arrangement environment and the material characteristics of the individual concrete structures 10 and the arrangement position of the corrosion detection sensor 2 in the concrete structure 10. The progress of the corrosive environment can be estimated with high accuracy.

  The reader / writer 3 has a function of estimating the possibility of the occurrence of cracks in the concrete structure 10 and the estimated time of occurrence based on the estimated progress of the corrosive environment in the concrete structure 10 by a technique such as FEM analysis. May be provided. Further, as shown in FIG. 5, when the reader / writer 3 is configured to be able to communicate with the server 40, information on the strength of the radio signal W2 read by the reader / writer 3 is transmitted to the server 40, and The calculation processing may be performed to calculate the expected crack generation time of the concrete structure 10, the required repair time, and the like.

  Note that, depending on the characteristics of the metal-compatible RF tag 4, there is a tag that transmits a radio signal W2 having the same intensity regardless of the intensity of the received radio signal W1. When the corrosion detection sensor 2 including the metal-compatible RF tag 4 is embedded in the concrete structure 10, the reader / writer 3 determines whether or not a communication environment has been established with the corrosion detection sensor 2. That is, whether or not the corrosive environment in the concrete structure 10 is progressing can be detected based on whether or not the radio wave signal W2 has been received.

  In this case, the position at which the reader / writer 3 is arranged is adjusted while changing the distance d1 (see FIG. 1) from the outer surface 10a of the concrete structure 10 so that the reader / writer 3 can receive the radio signal W2. Accordingly, the progress of the corrosive environment in the concrete structure 10 may be detected. When the value of the separation distance d1 at the time when the radio signal W2 can be received by the reader / writer 3 is smaller than a predetermined threshold, it is determined that the repair time of the concrete structure 10 has come. (It corresponds to the step (d)).

  As shown in FIG. 6, the corrosion detection sensor 2 may have a failure detection metal member 7 adhered to a part of the upper surface of the first surface 4a of the metal-compatible RF tag 4. FIG. 6 illustrates an example in which the corrosive metal member 5 is formed so as to cover the first surface 4a of the metal-compatible RF tag 4 and the failure detection metal member 7. An adhesive can be used to bond the first surface 4a of the metal-compatible RF tag 4 to the metal member 7 for failure detection.

  FIG. 7A is an example of a drawing schematically showing the first surface 4 a of the metal-compatible RF tag 4. In the example shown in FIG. 7A, the failure detecting metal member 7 is arranged at a position inside the outer periphery of the first surface 4a of the metal-compatible RF tag 4 so as to surround the central region of the first surface 4a in a rectangular shape. . 7A, illustration of the corrosive metal member 5 is omitted for convenience of explanation.

  As described above, the metal-compatible RF tag 4 can correctly receive the radio signal W1 transmitted from the reader / writer 3 when the metal material is present at a position opposite to the reader / writer 3. Conversely, if the metal-compatible RF tag 4 does not include the failure detecting metal member 7, it is corroded (thinned) to such an extent that the corrosive metal member 5 is almost lost (see FIG. 3B). As described above, the reader / writer 3 can hardly detect the radio signal W2 from the metal-compatible RF tag 4. In such a case, the worker may not be able to detect the radio signal W2 on the reader / writer 3 side because the metal-compatible RF tag 4 and / or the reader / writer 3 has failed, or a corrosive environment has progressed in the concrete member 11. As a result, the reader / writer 3 cannot recognize whether the radio signal W2 cannot be detected because the corrosive metal member 5 is greatly reduced in thickness.

  However, as shown in FIG. 6 and FIG. 7A, since the metal-compatible RF tag 4 includes the failure detection metal member 7, the corrosive environment is advanced to the extent that the corrosive metal member 5 is almost lost. Even in this case, the metal-compatible RF tag 4 can receive the radio signal W1 having the strength (the lowest reference strength) based on the failure detecting metal member 7, and the radio signal W2 corresponding to the radio signal W1 having this strength is read by the reader. It is transmitted to the writer 3 side. That is, if the radio signal W2 cannot be detected, the worker can recognize that the metal-compatible RF tag 4 and / or the reader / writer 3 is out of order. Further, the signal strength of the radio signal W2 received by the reader / writer 3 decreases within the range of the strength higher than the minimum reference strength according to the degree of progress of the deterioration of the corrosive metal member 5, so that By the same method, the degree of deterioration of the corrosive metal member 5, that is, the degree of progress of the corrosive environment in the concrete structure 10 in which the corrosion detection sensor 2 is disposed can be determined.

  The material of the failure detection metal member 7 is not particularly limited as long as it is a metal material that is less likely to deteriorate than the corrosive metal member 5, and copper, stainless steel, titanium, nickel, platinum, or the like can be used. Among them, stainless steel having high versatility and high rust resistance is preferable.

  The mode of arrangement of the failure detection metal member 7 on the first surface 4a of the metal-compatible RF tag 4 is not limited to the case of FIG. 7A. Another arrangement is shown in FIGS. 7B and 7C. In the mode shown in FIG. 7B, the failure detecting metal member 7 is arranged at a position inside the outer periphery of the first surface 4 a of the metal-compatible RF tag 4 so as to surround the central region of the first surface 4 a in a circular shape. . In the embodiment shown in FIG. 7C, the failure detection metal member 7 is arranged so as to be unevenly distributed in a part of the first surface 4a of the metal-compatible RF tag 4. 7A and 7B, the failure detecting metal member 7 is arranged so as not to be unevenly distributed on the first surface 4a of the metal-compatible RF tag 4 as compared with the arrangement of FIG. 7C. Thus, even if the corrosive metal member 5 is corroded (reduced in thickness) from any place, the degree of progress of the corrosive environment at the position where the corrosion detection sensor 2 is arranged can be more accurately estimated.

  7A to 7C, the corrosive metal member 5 and the metal member for failure detection are used in view of preventing the metal member 7 for failure detection and the corrosive metal member 5 from corroding different metals. It is preferable to insulate the corrosive metal member 5 from the failure detection metal member 7 by separating the corrosive metal member 5 from the failure detection metal member 7 or by interposing an insulating protective layer (for example, a resin sheet).

  Further, the corrosive metal member 5 is formed on almost the entire surface except for a part of the first surface 4a of the metal-compatible RF tag 4, and the first surface 4a of the metal-compatible RF tag 4 on which the corrosive metal member 5 is not formed. The failure detection metal member 7 may be formed thereon.

  When the embedding position of the corrosion detection sensor 2 is deep and a communication environment with the reader / writer 3 disposed outside the outer surface 10a of the concrete structure 10 cannot be formed, as shown in FIG. The reader / writer 3 may be embedded together with the corrosion detection sensor 2. In this case, only the signal line 17 connected to the reader / writer 3 is taken out of the concrete structure 10. Then, the worker connects the signal line 17 taken out of the concrete structure 10 to a predetermined reading device (not shown), and thereby the intensity of the radio signal W2 received by the reader / writer 3 through the signal line 17. (Or information on the presence or absence).

  When the reader / writer 3 is embedded in the concrete member 11, the presence of the reader / writer 3 does not hinder the progress of corrosion factors from the outer surface 10 a of the concrete structure 10 in the depth direction, as shown in FIG. 8. As shown, it is preferable that the reader / writer 3 is disposed at a position opposite to the outer surface 10a of the concrete structure 10 with respect to the corrosion detection sensor 2. More specifically, the corrosion detection sensor 2 is disposed so that the corrosive metal member 5 faces the outer surface 10a of the concrete structure 10, and the second surface of the metal-compatible RF tag 4 provided in the corrosion detection sensor 2 is provided. It is preferable that the reader / writer 3 be disposed so as to face 4b.

[Second embodiment]
Regarding the corrosion detection method and the corrosion detection sensor according to the second embodiment of the present invention, only different points from the first embodiment will be described.

  FIG. 9 is a drawing schematically showing an aspect of the second embodiment of the corrosion detection method according to the present invention. As in the case of FIG. 1, it is assumed that the object whose corrosion progress is to be detected is inside the concrete structure 10. More specifically, in the present embodiment, it is particularly assumed that the reinforcing bar 12 embedded in the concrete structure 10 is a target of corrosion detection. That is, the first embodiment detects the progress of the corrosive environment in the target space, whereas the second embodiment detects the progress of the corrosion of the target object itself.

  As shown in FIG. 9, in the present embodiment, the corrosion detection sensor 2 is attached to a reinforcing bar 12. The corrosion detecting sensor 2 may be embedded in the concrete member 11 together with the reinforcing bar 12 at the time of manufacturing the concrete structure 10, or a part of the existing concrete structure 10 may be scraped off to expose the reinforcing bar 12. Until the corrosion detection sensor 2 is attached to the reinforcing bar 12 and then backfilled with a protective member made of a nonmetallic material. When the corrosion detection sensor 2 is attached to the reinforcing bar 12, it may be attached using an adhesive, or a wire or a dedicated jig may be manufactured and attached. Thus, the step of attaching the corrosion detection sensor 2 to the reinforcing bar 12 corresponds to the step (a).

  FIG. 10A is a partially enlarged view of FIG. 9. In the present embodiment, the corrosion detection sensor 2 includes a plate-shaped metal-compatible RF tag 4 having a first surface 4a and a second surface 4b facing each other, and a reinforcing bar is provided on the first surface 4a side of the metal-compatible RF tag 4. 12 are located. And, unlike the first embodiment, the corrosion detection sensor 2 does not include the corrosive metal member 5.

  FIG. 10B is a schematic drawing when the reinforcing bar 12 is viewed from a direction orthogonal to the first surface 4 a of the metal-compatible RF tag 4. In FIG. 10B, the vertical direction on the paper corresponds to the direction in which the reinforcing bar 12 extends. As shown in FIG. 10B, the width 2L of the corrosion detection sensor 2 is preferably shorter than the width 12L of the reinforcing bar 12, and more preferably shorter than 50% of the width 12L of the reinforcing bar 12. In this case, when the reinforcing bar 12 is viewed from a direction orthogonal to the first surface 4a of the metal-compatible RF tag 4, as shown in FIG. 10B, the reinforcing bar 12 is arranged so as to surround the corrosion detection sensor 2. You. When the metal-compatible RF tag 4 is coin-shaped, its short radius may be regarded as the width 2L of the corrosion detection sensor 2.

  By arranging the corrosion detection sensor 2 in such a positional relationship, the corrosion factor that has progressed in the depth direction from the outer surface 10a of the concrete structure 10 is reduced to a position before the corrosion factor reaches the reinforcing bar 12. Is prevented from being hindered. Thereby, the detection accuracy of the corrosion detection sensor 2 is improved.

  At the time of the detection work, steps (a) to (c) are executed as in the first embodiment. That is, the worker places the brought reader / writer 3 at a position away from the metal-compatible RF tag 4 on the second surface 4b side, and transmits a radio frequency signal W1 of a predetermined frequency from the reader / writer 3 to the corrosion detection sensor 2. Radiates toward

  As shown in FIG. 9, in the present embodiment, when corrosion has not progressed, a metal reinforcing bar is provided on the surface (first surface 4 a) of the metal-compatible RF tag 4 opposite to the reader / writer 3. There are twelve. Therefore, a communication environment is established between the reader / writer 3 and the metal-compatible RF tag 4, and the reader / writer 3 receives the radio signal W2.

  On the other hand, as shown in FIG. 11, when a corrosive environment is progressing in the concrete structure 10 (in the concrete member 11), a part of the reinforcing bar 12 is changed to a metal compound 12a such as an oxide or a chloride. I do. In this case, the amount of the metal member located on the surface (first surface 4a) of the metal-compatible RF tag 4 opposite to the reader / writer 3 decreases, and the intensity of the radio signal W2 received by the reader / writer 3 decreases. Or, the reader / writer 3 cannot receive the radio signal W2 at all.

  That is, similarly to the first embodiment, when the intensity of the radio signal W2 received by the reader / writer 3 is low or when the radio signal W2 cannot be received, it is possible to detect that corrosion is progressing in the reinforcing bar 12. . Further, similarly to the first embodiment, when the reader / writer 3 is configured to receive the radio wave signal W2 of the same intensity, the position where the reader / writer 3 is arranged is set to the position from the outer surface 10a of the concrete structure 10. Adjustment may be made while changing the separation distance d1 (see FIG. 9), and the progress of corrosion in the reinforcing bar 12 may be detected according to the position where the reader / writer 3 has received the radio signal W2.

  Also in the present embodiment, as shown in FIG. 12, the corrosion detection sensor 2 may be configured such that the failure detection metal member 7 is adhered to a part of the upper surface of the first surface 4a of the metal-compatible RF tag 4. I do not care. Thus, whether or not the metal-compatible RF tag 4 and / or the reader / writer 3 has a failure can be detected based on whether or not the radio signal W2 is received on the reader / writer 3 side. Further, the degree of corrosion on the reinforcing bar 12 can be evaluated based on whether the radio signal W2 is higher or lower than a predetermined threshold.

  Similarly to the first embodiment, when the embedding position of the corrosion detection sensor 2 is deep, the reader / writer 3 may be embedded together with the corrosion detection sensor 2 (see FIGS. 13 and 14). In this case, it is preferable to dispose the reader / writer 3 so that the presence of the reader / writer 3 does not hinder the progress of the corrosion factor from the outer surface 10a of the concrete structure 10 in the depth direction. As shown in FIG. 13, the receiving surface of the reader / writer 3 and the transmitting surface of the metal-compatible RF tag may be inclined with respect to the outer surface 10a of the concrete structure 10, respectively. As another example, as shown in FIG. 14, the receiving surface of the reader / writer 3 and the transmitting surface of the metal-compatible RF tag are disposed so as to be substantially orthogonal to the outer surface 10 a of the concrete structure 10. It does not matter.

[Another embodiment]
Hereinafter, another embodiment will be described.

  <1> The corrosion detection sensor 2 may be embedded in a plurality of locations in the target space for detecting the progress of the corrosive environment. In this case, the depth position of each corrosion detection sensor 2 may be different. Thus, the progress of the corrosive environment can be recognized in more detail based on the difference in the intensity of the radio signal W2 transmitted from each of the corrosion detection sensors 2.

  <2> In the first embodiment, the corrosion detection sensor 2 may include a protection member for protecting the corrosive metal member 5 from proceeding in a corrosive environment. For example, as shown in FIG. 15, a protective sheet 8 formed so as to cover the first surface 4a side of the metal-compatible RF tag 4 may be attached, or as shown in FIG. Mortar 9 covering the entire circumference of sensor 2 may be formed. As the protection sheet 8, for example, a rust prevention sheet can be used.

  When attaching the corrosion detection sensor 2 of the first embodiment to the inside of the concrete structure 10, the corrosion detection sensor 2 is left on the site for about several days to one month in a state where it is exposed to the outside air, depending on work conditions. There are cases. In particular, when the concrete structure 10 is newly installed, the work may require many days. In such a case, when the corrosion detection sensor 2 is exposed to the outside air for several days, water is applied to the corrosive metal member 5 formed so as to cover the first surface 4a of the RF tag 4 for metal. Corrosion factors such as oxygen, chloride, etc. may adhere to the corrosive metal member 5 before it is disposed in the concrete structure 10.

  As described above, the corrosion detection sensor 2 is provided with the protection members (8, 9) that cover the first surface 4a side of the metal-compatible RF tag 4, so that the corrosion detection sensor 2 can be placed on the concrete structure 10 before it is disposed. The progress of corrosion on the corrosive metal member 5 is suppressed. Thereby, the detection accuracy of the corrosion detection sensor 2 can be improved.

  In addition, as shown in FIG. 15, when the corrosion detection sensor 2 is provided with the protection sheet 8, the protection sheet 8 is set immediately before the operation of mounting the corrosion detection sensor 2 in the target space (the concrete structure 10). After removal, the corrosion detection sensor 2 may be attached. Furthermore, the corrosion detection sensor 2 may be covered with mortar in order to prevent corrosion before the concrete is poured after installation and to prevent damage due to the impact at the time of placing.

  Further, as shown in FIG. 16, when the corrosion detection sensor 2 includes a mortar 9 covering the outer periphery, the corrosion detection sensor 2 may be attached while the mortar 9 is attached. Alternatively, the corrosion detection sensor 2 may be attached after the removal of the sensor 9.

  Since the mortar 9 has a space through which a certain amount of the corrosion factor passes, even if the corrosion detection sensor 2 is arranged in the target space with the mortar 9 attached, the corrosion factor is removed by the corrosive metal member 5. Is prevented from being hindered from proceeding. At this time, if the mortar 9 has a higher water-cement ratio than the concrete used for the structure, the early detection performance of the corrosion detection sensor 2 does not decrease.

  <3> In the above embodiment, the case where the target space (target object) for detecting the progress of the corrosive environment is the interior of the concrete structure 10 (the concrete member 11 and the reinforcing bar 12), but this is merely an example. It is. The corrosion detection sensor 2 of the present invention can be applied to any target space (object) that cannot be visually recognized from the outside and is likely to be corroded by a factor that corrodes the metal inside. It can be used for detecting the progress of corrosion.

  Hereinafter, a description will be given with reference to examples.

  As the corrosion detection sensor 2, a metal-compatible RF tag 4 corresponding to a 920 MHz band radio signal was employed. Then, the degree of corrosion of the reinforcing bar 12 disposed on the first surface 4a side of the corrosion detection sensor 2 was changed, and the intensity of the radio signal W2 read by the reader / writer 3 was measured. The reinforcing bar 12 used was a model D13 (nominal diameter 12.7 mm, outermost diameter 14 mm).

  The reader / writer 3 used had a corresponding signal frequency of 920 MHz band and output of 250 mW. The distance between the reader / writer 3 and the corrosion detection sensor 2 (RF tag 4 for metal) was fixed at 4 cm. The metal-compatible RF tag 4 has a size of 25 mm in width × 9 mm in height × 3 mm in thickness. Contacted.

Table 1 shows the results. The radio field intensity in Table 1 is a relative value.

  According to Table 1, it is shown that the strength of the radio signal W2 received by the reader / writer 3 decreases as the corrosion thickness of the reinforcing bar 12 increases. When a piece of concrete having a thickness of 1 cm is arranged between the reader / writer 3 and the corrosion detection sensor 2, when the reinforcing bar 12 having no corrosive layer is arranged and the radio signal W 2 received by the reader / writer 3 is read. It was also confirmed that the radio field intensity (RSSI) was 31.

  From this result, when the corrosion environment progresses and the corrosion of the reinforcing bar 12 progresses, the amount of the metal member provided on the first surface 4a side of the metal-compatible RF tag 4 opposite to the reader / writer 3 decreases. As a result, it can be seen that the intensity of the radio signal W2 received by the reader / writer 3 decreases. That is, it is confirmed that the progress of the corrosive environment can be detected and estimated based on the intensity of the radio signal W2 received by the reader / writer 3.

  From this result, as in the first embodiment, the corrosion detection sensor 2 includes the metal-compatible RF tag 4 and the corrosive metal member 5 formed on the first surface 4a of the metal-compatible RF tag. In this case, similarly, based on the strength of the radio wave signal W2 received by the reader / writer 3 from the position opposite to the corrosive metal member 5 (the second surface 4b side of the metal-compatible RF tag), the corrosive environment It can be seen that the progress can be detected and estimated.

2: Corrosion detection sensor 3: Reader / writer 4: Metal-compatible RF tag 4a: First surface of metal-compatible RF tag 4b: Second surface of metal-compatible RF tag 5: Corrosive metal member 5a: Metal compound 7: Failure detection Metal member 8: Protective sheet 9: Mortar 10: Concrete structure 10 a: Outer surface of concrete structure 11: Concrete member 12: Reinforcing bar 17: Signal line 31: Storage unit 32: Judgment processing unit 33: Display output unit 34: Communication unit 40: Server

Claims (11)

A corrosion detection sensor for detecting the progress of a corrosive environment in a target space that cannot be visually recognized from the outside,
A metal-compatible RF tag having a first surface and a second surface facing each other,
A corrosive metal member formed on the first surface of the metal-compatible RF tag to substantially cover the first surface,
A corrosion detection sensor, wherein the sensor is embedded and arranged so that the second surface of the metal-compatible RF tag can face a reader or a reader / writer. A corrosion detection sensor that detects the progress of corrosion on a metal object, which is arranged in a state invisible from the outside by being covered by the nonmetallic coating,
A metal-compatible RF tag having a first surface and a second surface facing each other,
The first surface of the metal-compatible RF tag is brought into contact with the object, and the second surface of the metal-compatible RF tag is embedded and arranged so as to face a reader or a reader / writer. Characteristic sensor for corrosion detection.   The corrosion detection sensor according to claim 2, wherein the object is a reinforcing bar in reinforced concrete.   The corrosion-detecting metal member according to any one of claims 1 to 3, further comprising: a failure-detecting metal member that shows corrosion resistance and is adhered to a part of the first surface of the metal-compatible RF tag. Sensor. A method for detecting the progress of a corrosive environment in a target space that cannot be visually recognized from the outside,
A metal-compatible RF tag having a first surface and a second surface facing each other, and a corrosive metal member formed on the first surface of the metal-compatible RF tag so as to substantially cover the first surface. Disposing the provided corrosion detection sensor in the target space (a);
(B) arranging a reader or reader / writer at a position away from the metal-compatible RF tag on the second surface side, and a radio signal transmitted from the metal-compatible RF tag by the reader or reader / writer A method for detecting corrosion, comprising the step of receiving (c). A method of detecting the progress of corrosion on a metal object, which is arranged in a state invisible from the outside by being covered by the nonmetallic object,
A step of arranging a corrosion detection sensor including a metal-compatible RF tag having a first surface and a second surface facing each other with the first surface of the metal-compatible RF tag in contact with the object ( a),
(B) arranging a reader or reader / writer at a position away from the metal-compatible RF tag on the second surface side, and a radio signal transmitted from the metal-compatible RF tag by the reader or reader / writer A method for detecting corrosion, comprising the step of receiving (c).   The step (a) is a step of arranging the corrosion detection sensor such that the object surrounds the periphery of the metal-compatible RF tag when viewed from a direction orthogonal to the first surface. The method for detecting corrosion according to claim 6, characterized in that:   The corrosion detection method according to claim 6, wherein the object is a reinforcing bar in reinforced concrete.   9. The method according to claim 5, wherein the step (c) includes a step of detecting a progress of a corrosive environment based on an intensity of the radio wave signal from the metal-compatible RF tag. 10. Corrosion detection method.   If the intensity of the radio signal read in the step (c) is lower than a predetermined threshold, the method further comprises a step (d) of determining that a corrosive environment is in progress. Item 10. The corrosion detection method according to Item 9.   The corrosion detection according to any one of claims 5 to 10, wherein the metal-compatible RF tag includes a failure detection metal member that is adhered to a portion on the first surface and that exhibits corrosion resistance. Method.

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