JP7105637B2 - Corrosion detection sensor, corrosion detection method - Google Patents

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 invisible from the outside or in an object placed in the same space, a method for detecting corrosion, and a sensor suitable for using this method.

Corrosion of reinforcing bars contained in a concrete structure greatly affects the durability of the concrete structure. Therefore, it is important to grasp the state of the corrosive environment of concrete structures in advance and to grasp the corrosion of reinforcing bars at an early stage.

The steel materials in concrete structures are protected from corrosion by a passive film formed on the surface of the steel materials because the concrete maintains an alkaline environment. However, when corrosive 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 to corrode the steel material.

When the steel material of a concrete structure corrodes, the steel material expands in volume, and the expansion pressure causes cracks in the concrete surface. When such cracks occur, corrosive factors are more likely to enter through the cracks, accelerating the progression of the corrosive environment. In other words, in a situation where cracks can be confirmed on the concrete surface, it is assumed that the concrete structure and the reinforcing bars existing therein have already deteriorated considerably.

In other words, there is a desire to grasp the progress of corrosion in a concrete structure before the corrosive environment inside the structure and the corrosion of reinforcing bars progress to the extent that changes 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, maintenance work can be carried out, for example, to cover the concrete surface with a predetermined material in order to prevent the intrusion of corrosive factors into the structure.

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

JP 2013-242163 A

In order to detect the state of corrosion of reinforcing bars inside concrete structures using the polarization resistance method, it is necessary to protrude the reinforcing bars, which are the target. That is, it is necessary to partially destroy (slightly destroy) the concrete structure. For this reason, a large amount of work is required to detect the state of internal corrosion, and the inspection work takes a long time.

In addition, it is not limited to concrete structures, and there are cases where it is necessary to detect the state of corrosion of structures whose interiors cannot be seen. obtain.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a method for detecting a corrosive environment or corrosive state in a target space invisible from the outside by a non-destructive and simple method, and a sensor suitable for the use of the method. and

A corrosion detection sensor according to the present invention includes:
A corrosion detection sensor that detects the progress of a corrosive environment in a target space that is invisible from the outside,
a metal-compatible RF tag having first and second surfaces facing each other;
a corrosive metal member formed on the first surface of the metal-compatible RF tag so as to substantially cover the first surface;
A first feature is that the metal-compatible RF tag is embedded and arranged so that the second surface can face a reader or a reader/writer.

By simulating a corrosive metal member as an object, this corrosion detection sensor is used to detect the progress of a corrosive environment in an object space that cannot be visually recognized from the outside. A corrosion detection sensor is placed in the target space, and a radio wave signal is received by a reader or reader/writer capable of communicating with the metal-compatible RF tag, thereby detecting the progress of the corrosive environment.

In this specification, the term "reader" refers to a device that has the function of reading radio signals transmitted from metal-compatible RF tags and does not have the function of writing information to metal-compatible RF tags. ” refers to a device having a function of reading radio signals transmitted from a metal-compatible RF tag and a function of writing information to the metal-compatible RF tag. In the following description, the term "reader" or "reader/writer" may be abbreviated as "reader/writer, etc." in order to avoid complication.

In this specification, the term “metal-compatible RF tag” means that if a metal material exists in the vicinity of the metal-compatible RF tag on the opposite side of the reader/writer, etc., It refers to an RF tag that has the property that while communication is established, the strength of a signal transmitted to a reader/writer or the like is extremely low if there is no metal material at the position.

For the sake of simplicity, the 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, placing a reader/writer etc. on the second surface side of the metal-compatible RF tag will cause the first surface of the metal-compatible RF tag to Since the metal material contained in the covering corrosive metal member exists on the opposite side of 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, corrosion progresses also to the corrosive metal member covering the first surface of the RF tag. At this time, the metal component disappears as the corrosive metal member changes to a metal compound. As a result, the reader/writer and the like do not form a communication environment with the metal-compatible RF tag, or the strength of the received radio signal decreases.

That is, it is possible to detect whether or not the corrosive environment is progressing in the target space or the degree of progress based on the presence or absence or intensity of the radio signal received by the reader/writer or the like.

Since the above-described corrosion detection sensor has a configuration in which a corrosive metal member is arranged on one side of the metal-compatible RF tag, it can be miniaturized. Therefore, the corrosion detection sensor can be arranged at a desired position within the target space. For example, by arranging the corrosion detection sensor at a position close to the outer surface of the target space, it is possible to detect the progress of the corrosive environment before the corrosive environment reaches 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 of the target space, the progress of the corrosive environment can be detected by the difference in the strength of the radio signal from each corrosion detection sensor. You can know more about the situation.

Further, the corrosion detection sensor according to the present invention is
A corrosion detection sensor that detects the progress of corrosion on a metal object that is arranged in a state that is invisible from the outside by being covered with a non-metal coating,
A metal-compatible RF tag having a first side and a second side 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 in such a manner as to face a reader or a reader/writer. Let it be the second feature.

If a corrosive environment progresses to some extent in the space where the metal object is arranged, corrosion progresses also to the metal object itself formed on the first surface of the metal-compatible RF tag. , some or all of the metal components contained in this object disappear. As a result, the reader/writer and the like do not form a communication environment with the metal-compatible RF tag, or the strength of the received radio signal decreases. Therefore, in the same way as the corrosion detection sensor of the first characteristic configuration, it is possible to detect the start of corrosion of the object itself, its progress, or the degree thereof, based on the presence or absence or intensity of radio signals received by a reader/writer or the like. can.

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

The corrosion detection sensor may include a corrosion-resistant failure detection metal member adhered to a portion of the first surface of the metal-compatible RF tag.

As described above, when the corrosive metal member or metal object present on the first surface of the metal-compatible RF tag is corroded and the residual amount of the metal material decreases, the signal is received by a reader/writer or the like. signal strength decreases. For this reason, when the corrosion of the corrosive metal member or the object is extremely advanced, there may be a case where the radio signal cannot be received at all by the reader/writer or the like. In such cases, it is necessary to determine whether the reader/writer, etc. and/or the metal-compatible RF tag is out of order, or whether corrosion has progressed to the extent that the corrosive metal member or object is completely lost. can't

On the other hand, as described above, by bonding the failure detection metal member to the metal-compatible RF tag in advance, the corrosion progressed to the extent that the corrosive metal member or metal object was lost. Even in this case, if the reader/writer or the like and/or the metal compatible RF tag is not out of order due to the presence of the metal member for failure detection, the reader/writer or the like has a predetermined strength (hereinafter referred to as "minimum reference strength"). ) radio signals can be received. Therefore, by comparing the strength of the radio signal actually received by the reader/writer or the like with this minimum reference strength, it is possible to estimate the state of corrosion in the target space or the target object. Moreover, when the radio signal cannot be received on the side of the reader/writer, etc., it can be recognized that the reader/writer and/or the metal-compatible RF tag is out of order.

In the corrosion detection sensor according to the first characteristic configuration, the corrosive metal member is preferably 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 failure detection metal member 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 failure detection metal member is formed on a part of the first surface of the metal compatible RF tag, and a corrosive metal member covers both the failure detection metal member and the first surface of the metal compatible RF tag. It does not matter if they are formed.

When a reader/writer or the like is arranged outside the target space (or the space where the target is covered), the corrosion detection sensor is preferably arranged so that the second surface of the metal compatible RF tag is positioned on the target. It is embedded and arranged so as to substantially face 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 even when the progress of the corrosive environment is not so advanced. In addition, the first surface of the RF tag and the outer surface of the target space “substantially face each other” means that the absolute value of the angle formed by the first surface and the outer surface is 45° or less. It doesn't matter. The absolute value of the angle is more preferably 30° or less, still more preferably 15° or less.

If 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 facing the outer surface of the metal-compatible RF tag. are placed.

The present invention is a method for detecting the progress of a corrosive environment in a target space invisible from the outside, comprising:
A plate-like 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 step (a) of arranging a corrosion detection sensor comprising a member in the target space;
A step (b) of disposing 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 the reader/writer and a step (c) of receiving the

The present invention also provides a method for detecting the progress of corrosion of a metallic object that is covered with a non-metallic coating and placed in a state that cannot be seen from the outside, comprising:
A corrosion detection sensor comprising a plate-like metal-compatible RF tag having a first surface and a second surface facing each other is arranged with the first surface of the metal-compatible RF tag in contact with the object. the step (a) of
A step (b) of disposing 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 the reader/writer and a step (c) of receiving the

In the step (a), the corrosion detection sensor may be arranged so that the object surrounds the metal-compatible RF tag when viewed in a direction orthogonal to the first surface. do not have. As a result, the presence of the metal-compatible RF tag prevents the corrosion factor from becoming a hindrance to the progress of corrosion on the metal object, and improves the detection accuracy of the progress of corrosion on the object. .

The step (c) may include a step of detecting progress of corrosion based on the presence or absence of the radio signal from the metal-compatible RF tag or the strength 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 strength of the radio signal read in the step (c) is below a predetermined threshold. I don't mind.

In addition, if the reader/writer, etc. is configured to detect only the presence or absence of radio signals from the metal-compatible RF tag, adjust the placement position of the reader/writer, etc., more specifically, the distance from the metal-compatible RF tag. By checking the presence or absence of radio signals while adjusting , it is possible to detect the progress of corrosion depending on the placement position of the reader/writer or the like that could receive the radio signals.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows typically the aspect of 1st embodiment of the corrosion (environment) detection method which concerns on this invention. It is a typical drawing for demonstrating the structure of the sensor for corrosion detection of 1st embodiment. FIG. 5 is a schematic drawing for explaining the structure of the corrosion detection sensor when a corrosive environment is progressing; FIG. FIG. 3B is a schematic drawing for explaining the structure of the corrosion detection sensor when the corrosive environment is further progressing from the state of FIG. 3A; FIG. 1 is an example of a functional block diagram of a reader/writer; FIG. 1 is an example of a functional block diagram of a reader/writer capable of communicating with a server; FIG. It is a typical drawing for demonstrating another structure of the sensor for corrosion detection of 1st embodiment. 1 is a plan view schematically showing one surface of a metal-compatible RF tag; FIG. FIG. 4 is another plan view schematically showing one surface of the metal-compatible RF tag. FIG. 10 is still another plan view schematically showing one surface of the metal-compatible RF tag. It is drawing which shows typically the aspect by which the sensor for a corrosion detection and a reader-writer are embedded. It is drawing which shows typically the aspect of 2nd embodiment of the corrosion detection method which concerns on this invention. It is a typical drawing for demonstrating the structure of the sensor for corrosion detection of 2nd embodiment. It is a typical drawing for demonstrating the structure of the sensor for corrosion detection of 2nd embodiment. FIG. 5 is a schematic drawing for explaining the mode of the corrosion detection sensor when corrosion is progressing; FIG. It is another typical drawing for demonstrating the structure of the sensor for corrosion detection of 2nd embodiment. It is drawing which shows typically the aspect by which the sensor for a corrosion detection and a reader-writer are embedded. It is drawing which shows typically the aspect by which the sensor for a corrosion detection and a reader-writer are embedded. FIG. 2 is a drawing schematically showing the structure of a corrosion detection sensor provided with a protective sheet as a protective member; FIG. It is drawing which shows typically the structure of the sensor for corrosion detection provided with the mortar as a protective member.

BEST MODE FOR CARRYING OUT THE INVENTION 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. It should be noted that in the following drawings, for convenience of explanation, some parts may be exaggerated, and the actual dimensional ratio and the dimensional ratio on the drawings do not necessarily match.

[First embodiment]
FIG. 1 is a drawing schematically showing an aspect of a first embodiment of a 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 arranged inside a concrete structure 10 (inside a concrete member 11). The corrosion detection sensor 2 may be embedded in advance in the concrete member 11 when the concrete structure 10 is manufactured, or may be protruded by scraping off a part of the existing concrete structure 10 and installed as a corrosion detection sensor. After embedding 2, it may be backfilled with a protective member made of a non-metallic material. Thus, the step of disposing the corrosion detection sensor 2 in the target space corresponds to 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-like metal-compatible RF tag 4 having a first surface 4 a and a second surface 4 b facing each other, and a corrosive sensor formed to cover the first surface 4 a of the metal-compatible RF tag 4 . and a metal member 5 .

The metal-compatible RF tag 4 incorporates an inductive antenna (not shown) and communicates with a radio frequency in a predetermined frequency band. When a metal material object exists 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 generates a radio signal (response signal). It is an RF tag capable of transmitting W2. As an example, the metal-compatible RF tag 4 is a plate-shaped 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, size , and any shape.

The corrosive metal member 5 is a metal material with low corrosion resistance, such as iron, zinc, and aluminum. The corrosive metal member 5 preferably has a foil shape, and can be formed by 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 onto the first surface 4a of the metal-compatible RF tag 4 via, for example, an adhesive. For example, the thickness of the corrosive metal member 5 is 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 so that the second surface 4 b of the metal-compatible RF tag substantially faces the outer surface 10 a 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 capable of wireless communication with the corrosion detection sensor 2 embedded in the concrete structure 10 to the concrete. Bring to the site of structure 10 . Then, the reader/writer 3 is placed in the vicinity of the area where the corrosion detection sensor 2 is embedded (corresponding to step (b)). More specifically, the reader/writer 3 is arranged at a position away from the metal-compatible RF tag 4 on the second surface 4b side. Note that the reader/writer 3 may be held by an operator's hand, or may be held by a holding member (not shown).

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

The reader/writer 3 may be a dedicated device, or may be 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 of using the "reader/writer 3" will be described as an example. A so-called "reader" that does not have a writing function may be used.

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 opposite to the reader/writer 3 (first A metal member is present on the side of surface 4a). 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 wave signal W2.

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

In other words, when the strength of the radio signal W2 received by the reader/writer 3 is low, it can be detected that the corrosive environment is progressing within the concrete structure 10 . For example, a threshold value indicating that the concrete structure 10 should be repaired is set in advance. (corresponding to step (d)).

The reader/writer 3 may have a function of displaying the degree of corrosion within the concrete structure 10 using, for example, a predetermined index (A/B/C, etc.) 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. As shown in FIG. 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 composed of a storage medium such as flash memory and hard disk. The determination processing unit 32 is a processing unit that performs arithmetic processing based on the acquired information, and is composed of dedicated hardware or software. The display output unit 33 is a functional unit that performs predetermined display arithmetic processing and displays the processed content on a monitor (not shown). The communication unit 34 is an interface for wireless communication.

Information corresponding to the correlation between the intensity of the radio signal W2 received from the corrosion detection sensor 2 and the progress of the corrosive environment in the concrete structure 10 (hereinafter referred to as "reference information") is stored in the storage unit 31 in advance. call.) is stored. When the communication unit 34 receives the radio 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 combines this reference information with the actually received radio signal W2. , and the progress of the corrosive environment in the concrete structure 10 is estimated. The display output unit 33 causes the monitor (not shown) provided in the reader/writer 3 to display information based on the determination result. As a result, the worker can recognize the progress of the corrosive environment in the concrete structure 10 only by checking the information on the monitor provided in the reader/writer 3 . If the reader/writer 3 is a general-purpose device such as a smart phone or a tablet PC, the monitor corresponds to the 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) attached to the corrosion detection sensor 2 in advance. 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 related to the concrete structure 10 corresponding to the identification information i1 from the server 40, and stores the reference information in the storage unit 31. store (temporarily) in Then, the determination processing unit 32 estimates the progress of the corrosive environment in the concrete structure 10 based on the strength of the radio signal W2 actually received and the reference information downloaded from the server 40. FIG.

According to this method, based on the reference information considering the arrangement environment and material characteristics of each concrete structure 10, the arrangement position of the corrosion detection sensor 2 in the concrete structure 10, etc., The progress of the corrosive environment can be estimated with high accuracy.

Note that the reader/writer 3 has a function of estimating the possibility of occurrence of cracks in the concrete structure 10 and the expected time of crack occurrence by a method such as FEM analysis based on the estimated progress of the corrosive environment in the concrete structure 10. can have Further, as shown in FIG. 5, when the reader/writer 3 is configured to be able to communicate with the server 40, information regarding the intensity of the radio signal W2 read by the reader/writer 3 is transmitted to the server 40, and the server 40 side By performing the arithmetic processing in , the expected time of occurrence of cracks in the concrete structure 10, the necessary repair time, and the like may be calculated.

It should be noted that depending on the characteristics of the metal-compatible RF tag 4, there are those that transmit the radio signal W2 of the same strength regardless of the strength 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 a communication environment has been established with the corrosion detection sensor 2. That is, progress of the corrosive environment in the concrete structure 10 can be detected depending on whether or not the radio signal W2 has been received.

In this case, the position where the reader/writer 3 is arranged is adjusted while changing the separation 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 within the concrete structure 10 may be detected. When the distance d1 is smaller than a predetermined threshold at the time when the radio signal W2 can be received by the reader/writer 3, it is determined that the time to repair the concrete structure 10 has come. (corresponding to step (d)).

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

FIG. 7A is an example of a drawing schematically showing the first surface 4a of the metal-compatible RF tag 4. FIG. In the example shown in FIG. 7A, at a position inside the outer periphery of the first surface 4a of the metal-compatible RF tag 4, the failure detection metal member 7 is arranged so as to surround the central region of the first surface 4a in a rectangular shape. . In addition, in FIG. 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 there is a metal material on the opposite side of the reader/writer 3 . Conversely, if the metal-compatible RF tag 4 does not include the failure detection metal member 7, the corrosive metal member 5 is corroded (thickened) to the extent that it 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 wonders whether the radio signal W2 cannot be detected on the reader/writer 3 side because the metal-compatible RF tag 4 and/or the reader/writer 3 is out of order, or whether a corrosive environment has progressed in the concrete member 11. As a result, it is not possible to recognize whether the radio signal W2 cannot be detected on the reader/writer 3 side because the corrosive metal member 5 is greatly reduced.

However, as shown in FIGS. 6 and 7A, if the metal-compatible RF tag 4 includes the failure detection metal member 7, the corrosive environment progresses to the extent that the corrosive metal member 5 is almost lost. Even in such a case, since the metal-compatible RF tag 4 can receive the radio signal W1 having the strength (minimum reference strength) based on the failure detection metal member 7, the radio signal W2 corresponding to the radio signal W1 having this strength is transmitted to the reader. It is sent to the writer 3 side. In other words, the operator can recognize that the metal-compatible RF tag 4 and/or the reader/writer 3 is out of order when the radio signal W2 cannot be detected. In addition, since the signal strength of the radio signal W2 received by the reader/writer 3 decreases in accordance with the progress of deterioration of the corrosive metal member 5 within a range of strength higher than the minimum reference strength, A similar method can be used to determine the degree of deterioration of the corrosive metal member 5, that is, the degree of progression of the corrosive environment within the concrete structure 10 in which the corrosion detection sensor 2 is arranged.

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 these, stainless steel is preferred because of its high versatility and high resistance to rust.

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. An alternative arrangement is shown in Figures 7B and 7C. In the embodiment shown in FIG. 7B, the failure detection metal member 7 is arranged so as to circularly surround the central region of the first surface 4a at a position inside the outer circumference of the first surface 4a of the metal-compatible RF tag 4. . In addition, in the mode shown in FIG. 7C, the failure detection metal member 7 is arranged so as to be unevenly distributed in a partial region of the first surface 4a of the metal-compatible RF tag 4 . 7C, the failure detection 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 in the arrangement of FIGS. 7A and 7B. Therefore, no matter where the corrosive metal member 5 is corroded (thickened), the progress of the corrosive environment at the position where the corrosion detection sensor 2 is arranged can be estimated more accurately.

7A to 7C, from the viewpoint of preventing corrosion of the failure detection metal member 7 and the corrosive metal member 5 from dissimilar metal corrosion, the corrosive metal member 5 and the failure detection metal member 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).

In addition, the corrosive metal member 5 is formed on almost the entire surface of the first surface 4a of the metal-compatible RF tag 4 except for a partial area, 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 embedded position of the corrosion detection sensor 2 is deep and a communication environment cannot be formed with the reader/writer 3 arranged outside the outer surface 10a of the concrete structure 10, 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 to the outside of the concrete structure 10 to a predetermined reading device (not shown), so that the intensity of the radio signal W2 received by the reader/writer 3 through the signal line 17 is measured. (or information about the presence or absence).

When the reader/writer 3 is embedded in the concrete member 11, the presence of the reader/writer 3 should not hinder the progression of corrosion factors in the depth direction from the outer surface 10a of the concrete structure 10, as shown in FIG. As shown, it is preferable to arrange the reader/writer 3 on the side 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 arranged 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 with this corrosion detection sensor 2 is It is preferable to arrange the reader/writer 3 so as to face 4b.

[Second embodiment]
The second embodiment of the corrosion detection method and corrosion detection sensor according to the present invention will be described only with respect to the points that differ from the first embodiment.

FIG. 9 is a drawing schematically showing an aspect of a 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 for detecting the progress of corrosion is the inside of the concrete structure 10 . More specifically, in this embodiment, it is assumed that the reinforcing bars 12 embedded in the concrete structure 10 are to be subjected to 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 corrosion of the object itself.

As shown in FIG. 9, the corrosion detection sensor 2 is attached to the reinforcing bar 12 in this embodiment. The corrosion detection sensor 2 may be embedded in the concrete member 11 together with the reinforcing bar 12 in advance when the concrete structure 10 is manufactured, or the existing concrete structure 10 may be partly scraped off to expose the reinforcing bar 12 . After the corrosion detection sensor 2 is attached to the reinforcing bar 12, it may be backfilled with a protective member made of a non-metallic material. When attaching the corrosion detection sensor 2 to the reinforcing bar 12, it may be attached using an adhesive, or may be attached by manufacturing a wire or a special jig. Thus, the step of attaching the corrosion detection sensor 2 to the reinforcing bar 12 corresponds to step (a).

10A is a partially enlarged view of FIG. 9. FIG. In this embodiment, the corrosion detection sensor 2 includes a plate-like metal-compatible RF tag 4 having a first surface 4a and a second surface 4b facing each other. 12 are positioned. 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 4a of the metal-compatible RF tag 4. FIG. In FIG. 10B , the vertical direction of the paper corresponds to the extension direction of the reinforcing bars 12 . 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 bars 12 are viewed from the direction perpendicular to the first surface 4a of the metal-compatible RF tag 4, the reinforcing bars 12 are arranged to surround the corrosion detection sensor 2 as shown in FIG. 10B. be. If the metal-compatible RF tag 4 is coin-shaped, the minor radius of the coin-shaped coin 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 advancing in the depth direction from the outer surface 10 a of the concrete structure 10 is detected at a position before reaching the reinforcing bar 12 . is inhibited from being disturbed by As a result, the detection accuracy of the corrosion detection sensor 2 is enhanced.

During the detection work, steps (a) to (c) are performed in the same manner as in the first embodiment. That is, the worker places the reader/writer 3 brought by him/herself at a position away from the metal-compatible RF tag 4 on the second surface 4b side, and emits a radio wave signal W1 of a predetermined frequency from the reader/writer 3 to the corrosion detection sensor 2. radiate toward

As shown in FIG. 9, in this embodiment, in a state where corrosion has not progressed, a metal reinforcing bar is provided on the surface (first surface 4a) of the metal-compatible RF tag 4 opposite to the reader/writer 3. 12 exist. 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 wave signal W2.

On the other hand, as shown in FIG. 11, when a corrosive environment progresses in the concrete structure 10 (inside the concrete members 11), part of the reinforcing bars 12 changes to metal compounds 12a such as oxides and chlorides. do. In this case, the amount of the metal member positioned on the side (first surface 4a) of the metal-compatible RF tag 4 opposite to the reader/writer 3 decreases, and the strength of the radio signal W2 received by the reader/writer 3 decreases. Alternatively, the reader/writer 3 cannot receive the radio wave signal W2 at all.

That is, as in the first embodiment, when the strength 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 the reinforcing bar 12 is being corroded. . Further, as in the first embodiment, when the reader/writer 3 is configured to receive the radio signal W2 of the same intensity, the position at which the reader/writer 3 is arranged is changed from the outer surface 10a of the concrete structure 10 to The progress of corrosion in the reinforcing bar 12 may be detected according to the position at which the reader/writer 3 can receive the radio signal W2 by adjusting while changing the separation distance d1 (see FIG. 9).

In this embodiment, as shown in FIG. 12, even if the corrosion detection sensor 2 has the failure detection metal member 7 adhered to a part of the first surface 4a of the metal compatible RF tag 4, I do not care. Accordingly, whether or not the RF tag 4 corresponding to metal and/or the reader/writer 3 is out of order can be detected depending on whether or not the radio signal W2 is received on the reader/writer 3 side. Also, the degree of corrosion of the reinforcing bars 12 can be evaluated depending on whether the radio signal W2 is higher or lower than a predetermined threshold.

As in the first embodiment, when the corrosion detection sensor 2 is embedded 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 arrange the reader/writer 3 so that the presence of the reader/writer 3 does not impede the progression of corrosion factors in the depth direction from the outer surface 10a of the concrete structure 10 . 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 arranged so as to be substantially orthogonal to the outer surface 10a of the concrete structure 10. It doesn't matter if you let them.

[Another embodiment]
Another embodiment will be described below.

<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 positions of the respective corrosion detection sensors 2 may be made different. As a result, the progress of the corrosive environment can be recognized in more detail from the difference in intensity of the radio signal W2 transmitted from each corrosion detection sensor 2 .

<2> In the first embodiment, the corrosion detection sensor 2 may be provided with a protective member for protecting the corrosive metal member 5 from progressing of the 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, and as shown in FIG. A mortar 9 covering the entire circumference of the sensor 2 may be formed. As the protective sheet 8, for example, an antirust sheet can be used.

When installing the corrosion detection sensor 2 of the first embodiment inside the concrete structure 10, depending on the work situation, the corrosion detection sensor 2 is left exposed to the outside air at the site for several days to a month. Sometimes. In particular, when constructing a new concrete structure 10, the work may take many days. In such a case, if the corrosion detection sensor 2 is exposed to the outside air for several days, the corrosive metal member 5 formed so as to cover the first surface 4a of the metal-compatible RF tag 4 is exposed to water. Corrosion factors such as , oxygen, and chlorides adhere to the corrosive metal member 5 , which may partially corrode the corrosive metal member 5 before it is placed in the concrete structure 10 .

As described above, the corrosion detection sensor 2 is provided with the protective members (8, 9) covering the first surface 4a side of the metal compatible RF tag 4, so that the corrosion detection sensor 2 can The progress of corrosion to the corrosive metal member 5 is suppressed. Thereby, the detection accuracy of the corrosion detection sensor 2 can be improved.

As shown in FIG. 15, when the corrosion detection sensor 2 is provided with a protective sheet 8, the protective sheet 8 is removed immediately before the work of installing the corrosion detection sensor 2 in the target space (concrete structure 10). The corrosion detection sensor 2 may be attached after removal. Further, the corrosion detection sensor 2 may be covered with mortar after installation in order to prevent corrosion until concrete is placed and to prevent damage due to impact during placement.

Further, as shown in FIG. 16, when the corrosion detection sensor 2 is provided with the mortar 9 covering the outer periphery, the corrosion detection sensor 2 may be attached while the mortar 9 is still attached. The corrosion detection sensor 2 may be attached after removing 9 .

Since the mortar 9 has a space through which a certain amount of the corrosive factor passes, even if the corrosion detection sensor 2 is arranged in the target space with the mortar 9 attached, the corrosive factor is detected by the corrosive metal member 5 . is suppressed. 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 will not deteriorate.

<3> In the above embodiment, the case where the target space (object) for detecting the progress of the corrosive environment is the inside of the concrete structure 10 (concrete members 11 and reinforcing bars 12) has been described, but this is only an example. 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 that may corrode inside due to the progress of factors that corrode metal into the interior. It can be used for detecting the progress of corrosion state).

Examples will be described below.

As the corrosion detection sensor 2, a metal-compatible RF tag 4 compatible with radio signals in the 920 MHz band was adopted. Then, the strength of the radio signal W2 read by the reader/writer 3 was measured while changing the degree of corrosion of the reinforcing bar 12 arranged on the first surface 4a side of the corrosion detection sensor 2 . As the reinforcing bar 12, a type D13 (nominal diameter: 12.7 mm, outermost diameter: 14 mm) was adopted.

The reader/writer 3 has a corresponding signal frequency of 920 MHz and an output of 250 mW. The distance between the reader/writer 3 and the corrosion detection sensor 2 (metal-compatible RF tag 4) was fixed at 4 cm. The metal-compatible RF tag 4 has dimensions of 25 mm in width, 9 mm in length, and 3 mm in thickness. made contact.

The results are shown in Table 1. In addition, the radio wave intensity in Table 1 is a relative value.

Table 1 shows 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. In addition, when a piece of concrete with a thickness of 1 cm is placed between the reader/writer 3 and the corrosion detection sensor 2, if a reinforcing bar 12 without a corroded layer is placed and the radio signal W2 received by the reader/writer 3 is read, , it was confirmed that the radio wave intensity (RSSI) was 31 as well.

From this result, as the corrosive environment progresses and the corrosion of the reinforcing bar 12 progresses, the amount of the metal member provided on the first surface 4a side, which is the opposite side of the reader/writer 3 of the metal compatible RF tag 4, decreases. As a result, it can be seen that the strength of the radio signal W2 received by the reader/writer 3 is reduced. In other words, 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, like 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 intensity of the radio 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 is determined. It can be seen that the progress can be detected and estimated.

2: Corrosion detection sensor 3: Reader/writer 4: RF tag for metal 4a: First surface of RF tag for metal 4b: Second surface of RF tag for metal 5: Corrosive metal member 5a: Metal compound 7: Failure detection 8: Protective sheet 9: Mortar 10: Concrete structure 10a: 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 (7)

A method for detecting the progress of a corrosive environment in a target space invisible from the outside, comprising:
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. a step (a) of arranging a corrosion detection sensor provided in the target space;
A step (b) of disposing 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 the reader/writer A method of detecting corrosion, comprising the step (c) of receiving A method for detecting the progress of corrosion on a metallic object placed in a state invisible from the outside by being covered with a non-metallic coating, comprising:
A step of arranging a corrosion detection sensor comprising 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),
A step (b) of disposing 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 the reader/writer A method of detecting corrosion, comprising the step (c) of receiving The step (a) is a step of arranging the corrosion detection sensor so that the object surrounds the metal-compatible RF tag when viewed in a direction orthogonal to the first surface. The corrosion detection method according to claim 2 , characterized by: 4. The corrosion detection method according to claim 2 , wherein said object is a reinforcing bar in reinforced concrete. The step (c) according to any one of claims 1 to 4 , characterized in that the step (c) includes a step of detecting the progress of the corrosive environment based on the strength of the radio signal from the metal-compatible RF tag. corrosion detection method. The method further comprises a step (d) of determining that a corrosive environment is progressing when the intensity of the radio signal read in the step (c) is below a predetermined threshold. Item 6. The corrosion detection method according to item 5 . The corrosion detection according to any one of claims 1 to 6 , wherein the metal-compatible RF tag comprises a corrosion-resistant failure detection metal member adhered to a portion of the first surface. Method.

Images