JP7441152B2 - System for estimating the amount of water contained in a cement water kneaded product, method for estimating the amount of water contained in a cement water kneaded product, and sensor for estimating the amount of water contained in a cement water kneaded product - Google Patents

Description

The present invention relates to a system and method for estimating the amount of water contained in a cement water kneaded body. The present invention also relates to a sensor that can be used for such estimation processing.

Understanding the amount of moisture in concrete and mortar is highly important from the perspective of efficient management of durability.

Conventionally, methods using an electrical resistance method and methods using a humidity sensor are known as methods for determining the amount of moisture in concrete after hardening (hereinafter referred to as "hardened concrete"). Furthermore, as another method, a method of estimating the amount of water using neutrons is known, as disclosed in Patent Document 1 below.

It is known that moisture accelerates the deterioration of hardened concrete when a concrete structure is in service. Penetration of water plays a role in transporting carbon dioxide and chloride ions, and after carbon dioxide neutralization, reinforcing steel is more likely to be corroded by chloride ions. Therefore, it is important to understand the moisture content in hardened concrete and the risk of reinforcing steel corrosion from the perspective of ensuring durability.

JP2017-9371A

However, in the case of measurement using the conventional electrical resistance method, it is possible to measure the moisture content only in a very small shallow area from the surface of hardened concrete. Further, in the case of measurement using a humidity sensor, since the measured value is information regarding humidity, it is difficult to accurately measure the moisture content over a wide range of hardened concrete.

Further, in the case of the method described in Patent Document 1, a dedicated device such as a neutron generation source is required, and it cannot be said to be a realistic method for general use at each work site.

Furthermore, although all of the conventional methods for measuring moisture content described above can be performed on hardened concrete, this method can be used to measure the amount of moisture contained in a cement-water mixture that has not yet hardened, such as fresh concrete or fresh mortar. is not available.

In the floor concrete construction stage, finishing work is carried out after a certain period of time has elapsed after fresh concrete has been poured and solidification has progressed. However, for example, determining when to finish the hardened surface of fresh concrete depends largely on the builder's intuition, and there is a problem in that the timing of the decision varies depending on the skill level of the builder. Therefore, there is a need for technology that can appropriately judge the timing of work without depending on the skill level of the builder and efficiently manage the durability of concrete.

In view of the above-mentioned problems, the present invention can be used for cement-water kneaded bodies in any state before hardening or after hardening, and can estimate the amount of water contained in cement-water kneaded bodies by a simple method. The purpose is to provide a system and method that can. Another object of the present invention is to provide a sensor for estimating the amount of water contained in a cement water kneaded body, which can be used to implement such a method.

The present invention is a system for estimating the amount of water contained in a cement water mixture belonging to any one of fresh concrete after placement, hardened concrete, fresh mortar after placement, or hardened mortar, comprising:
an RF tag embedded in the cement water kneaded body;
a reader or reader/writer capable of transmitting and receiving radio signals to and from the RF tag;
Based on an index value of at least one of the intensity value of the radio wave signal received by the reader or reader/writer, or the upper limit threshold of the separation distance between the reader/reader/writer and the cement water kneaded body that can detect reception of the radio signal. and an estimation device for estimating the amount of water contained in the cement water kneaded body.

As used herein, the term "cement water kneaded product" refers to a kneaded mixture containing at least cement and water, and the degree of hardening thereof does not matter. That is, the cement water kneaded body includes, for example, fresh concrete, hardened concrete, fresh mortar, or hardened mortar.

In this specification, a "reader" refers to a device that has the function of reading radio wave signals transmitted from an RF tag, but does not have a function of writing information to the RF tag. Refers to a device that has the function of reading radio wave signals transmitted from an RF tag and the function of writing information to an RF tag. Hereinafter, to avoid complexity, the term "reader" or "reader/writer" may be abbreviated as "reader/writer, etc.".

Since water is conductive, it exhibits the property of absorbing radio waves. Therefore, if moisture exists between the RF tag embedded in the cement-water mixture and the surface of the cement-water mixture, communication between the reader/writer and the like and the RF tag will be interfered with. The degree of this interference increases as the amount of water increases. In other words, the greater the amount of water contained in the cement water kneaded body, the lower the radio wave intensity that can be received by a reader/writer or the like tends to be. In addition, if the distance between the reader/writer, etc. and the surface of the cement water mixture is reduced until the reader/writer, etc. can receive the radio wave signal from the RF tag, it is necessary to The larger the amount of water that is absorbed, the narrower the separation distance becomes.

Therefore, according to the above system, based on the intensity value of the radio signal received by the reader/writer, etc., or the upper limit threshold of the separation distance between the reader/writer, etc., which can detect the reception of the radio wave signal, and the cement water kneaded body, The amount of water contained in the water kneaded body can be estimated. In particular, if you embed an RF tag in fresh concrete or fresh mortar in advance, you can estimate the amount of water contained in the cement-water mixture by simply bringing a reader/writer close to the cement-water mixture and receiving radio signals. , moisture content can be estimated using an extremely simple method.

Furthermore, the above system is configured to estimate the amount of water contained in the cement water mixture based on reception of radio wave signals between the buried RF tag and a reader/writer installed outside the cement water mixture. be. For this reason, unlike conventional methods, the amount of water contained only in the vicinity of the surface of the cement-water mixture is not measured, but, in principle, a wide area can be measured in the depth direction from the surface of the cement-water mixture to the embedding position of the RF tag. The amount of water contained in the cement water mixture can be estimated for the area.

For example, when the cement water kneaded body is fresh concrete or fresh mortar before hardening, free water decreases as hardening progresses due to a hydration reaction. Therefore, by confirming that the intensity of radio waves received by a reader/writer etc. has increased, the degree of progress of the hydration reaction in the cement composition can be recognized, and the degree of hardening of fresh concrete or fresh mortar can be recognized. can be confirmed. Since the hydration reaction occurs almost uniformly throughout the fresh concrete or fresh mortar, the intensity value of the radio wave signal received by the reader/writer, etc., or the upper limit threshold value of the separation distance between the reader/writer, etc. and the cement water mixture It is possible to estimate the amount of water contained in fresh concrete or fresh mortar.

Further, for example, when the cement water kneaded body is hardened concrete or hardened mortar, it is conceivable that moisture due to rainwater, dew condensation, etc. permeates inside and increases the water content. In particular, when the cement-water mixture is a concrete structure, it generally contains reinforcing bars, and there is a risk that the reinforcing bars may be corroded by the water that has penetrated. Furthermore, even with hardened mortar, water entering from the outside may react and bond with soluble substances inside, causing efflorescence on the surface.

If the cement water mixture is such hardened concrete or hardened mortar, by confirming that the strength of the radio waves received by a reader/writer etc. has decreased, the inside of the cement water mixture can be detected. It can be recognized that the amount of water that has penetrated is increasing. The phenomenon in which moisture penetrates into hardened concrete or hardened mortar from the outside occurs almost uniformly throughout the hardened concrete or hardened mortar, so the intensity value of the radio wave signal received by a reader/writer, etc., or the above-mentioned reader/writer It is possible to estimate the amount of water contained in fresh concrete or fresh mortar based on the upper limit threshold of the separation distance between the water and the cement-water kneaded body.

This estimation device may be installed in a reader/writer or the like, or may be configured as a separate device from the reader/writer and the like. In the former case, the estimating device may be a software means that estimates the amount of water contained in the cement water kneaded body by performing predetermined arithmetic processing based on the inputted index value. In the latter case, it may be a computer or a dedicated hardware device that can communicate with a reader/writer or the like and is equipped with a function to perform the arithmetic processing.

The system includes a storage unit in which information regarding a correlation between the index value and the amount of water contained in the cement water kneaded body is recorded,
The estimating device may read information regarding the correlation from the storage unit and estimate the amount of water contained in the cement water kneaded body corresponding to the measured index value.

This storage unit can be configured by, for example, a memory installed in a reader/writer or a device separate from the reader/writer. Furthermore, the information regarding the correlation may be written in the form of a data table or in the form of a function.

The RF tag includes a first RF tag and a second RF tag embedded at different depths in the cement water kneading body,
The estimation device has a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. The amount of water contained in the cement water kneaded body may be estimated based on the comparison result with a certain second index value.

When estimating the amount of water contained in the cement water mixture based on the intensity value of the radio wave signal received by a reader/writer, etc., in order to increase the estimation accuracy, it is necessary to set a predetermined distance between the reader/writer, etc. and the surface of the cement water mixture. It is preferable to set the value to . However, in reality, it is expected that the position of the reader/writer etc. will change when the estimation process is executed.

On the other hand, according to the above configuration, the first RF tag and the second RF tag are buried in advance at different buried depths in the cement water kneaded body. Therefore, even if the distance between the reader/writer, etc. and the surface of the cement water mixture changes, the distance between the reader/writer, etc. and the first RF tag (first separation distance) and the distance between the reader/writer, etc. and the second RF tag change. The difference between the separation distance from the RF tag (second separation distance) is fixed by the difference in the buried depth position. Therefore, the comparison result between the first index value based on the strength value of the radio wave signal from the first RF tag and the second index value based on the strength value of the radio wave signal from the second RF tag, more specifically, the difference value. Based on this, it is possible to accurately estimate the amount of water present in the area between the buried position of the first RF tag and the buried position of the second RF tag in the cement water kneaded body, and based on this estimated value, the amount of water present in the cement water mixed body The amount of water present throughout can be estimated with high accuracy.

The system has a tag protector embedded in the cement water kneaded body and made of a material having a lower water absorption rate than the cement water kneaded body,
The RF tag includes a first RF tag embedded within the tag protector and a second RF tag embedded within the cement water mixer at a location outside the tag protector;
The estimation device has a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. The amount of water contained in the cement water kneaded body may be estimated based on the comparison result with a certain second index value.

According to such a configuration, as described above, when estimating the amount of water contained in the cement water mixture based on the intensity value of the radio signal received by the reader/writer, etc., the position of the reader/writer, etc. is determined when the estimation process is executed. Although it is expected that the value will vary, the first RF tag embedded in the tag protector made of a material with low water absorption rate and the second RF tag placed in the area outside the cement water kneading body are is buried.

Therefore, in the depth direction, the amount of water contained in the area between the first RF tag and the surface of the cement water kneaded body in the cement water kneaded body and the amount of water contained in the area between the second RF tag and the surface of the cement water kneaded body are There is a difference in the amount of water contained in the area between the two, which is based on the difference between the water absorption rate of the tag protector and the water absorption rate of the cement water kneaded body. As a result, based on the comparison result between the first index value based on the intensity value of the radio wave signal from the first RF tag and the second index value based on the intensity value of the radio wave signal from the second RF tag, cement water kneading is performed. It is possible to estimate the amount of water contained in the region between the buried position of the second RF tag and the surface of the cement water mixture in the body. In particular, by burying both the first RF tag and the second RF tag at approximately the same depth, the ratio of the first index value to the second index value and the water absorption rate of the tag protector can be adjusted. Based on the water absorption ratio of the cement water mixture, the amount of water existing in the area between the buried positions of the second RF tag can be estimated with high accuracy, and based on this estimate, the water content in the entire cement water mixture can be estimated. The amount of water present can be estimated with high accuracy.

In order to make the embedding depth of both the first RF tag and the second RF tag the same, for example, the second RF tag can be buried in advance in hardened concrete or hardened mortar made of the same material as the cement water mixture. In addition to preparing a buried tag object, a method is adopted in which the tag protector in which the first RF tag is buried and the buried tag object in which the second RF tag is buried are both buried in the cement water mixture. can.

The material for the tag protector preferably has a water absorption rate of less than 5%, more preferably less than 3%, and particularly preferably less than 1%. Furthermore, the material for the tag protector preferably has a dielectric constant comparable to that of the cement water kneaded material. From this point of view, the tag protector can suitably be made of ultra-high strength concrete, ceramics, ABS, or resin such as polyethylene or polypropylene.

The system includes a spacer embedded in the cement water mixer and having the RF tag fixed thereto;
The RF tag records depth information regarding the burial depth from the surface of the cement water kneaded body,
The reader or reader/writer receives the depth information together with the intensity value of the radio signal from the RF tag,
The estimating device calculates the cement water kneading body based on the intensity value of the radio signal received by the reader or reader/writer, the depth information, and the separation distance between the reader or reader/writer and the cement water kneading body. It may also be used to estimate the amount of water contained in the body.

As mentioned above, when estimating the amount of water contained in a cement water mixture based on the intensity value of the radio signal received by a reader/writer, etc., it is expected that the position of the reader/writer, etc. will change when the estimation process is executed. . According to the above configuration, information about the burial depth is recorded in advance on the RF tag side, and the intensity value and depth information of the radio wave signal can be received by a reader/writer or the like. Furthermore, the distance between the reader/writer, etc. and the surface of the cement water kneaded body during execution of the estimation process can be actually measured. Therefore, the surface of the RF tag and the cement water kneaded body is determined by arithmetic processing based on the received radio wave intensity value, depth information regarding the buried depth of the RF tag, and the distance between the reader/writer, etc. and the cement water kneaded body. It is possible to estimate the amount of water in the cement-water mixture between the

The present invention is a method for estimating the amount of water contained in a cement water mixture belonging to any one of fresh concrete after placement, hardened concrete, fresh mortar after placement, or hardened mortar, comprising:
a step (a) of embedding an RF tag in the cement water kneaded body;
a step (b) of arranging a reader or reader/writer capable of transmitting and receiving radio signals to and from the RF tag at a predetermined position outside the cement water kneaded body;
Measure an index value of at least one of the intensity value of the radio wave signal received by the reader or reader/writer, or the upper limit threshold of the separation distance between the reader/reader/writer and the cement water kneaded body that can detect the reception of the radio signal. step (c) of
The method is characterized by comprising a step (d) of estimating the amount of water contained in the cement water kneaded body based on the index value.

According to the above method, the amount of water contained in concrete or mortar, whether before or after hardening, can be estimated by a simple method.

The present invention also provides a sensor for estimating the amount of water contained in a cement water mixture belonging to any one of fresh concrete after placement, hardened concrete, fresh mortar after placement, or hardened mortar,
an RF tag that can communicate with a reader or reader/writer;
The RF tag is fixed to the inside, and a spacer is provided for adjusting the embedding depth of the RF tag in the cement water kneading body.

According to this sensor, the depth position of the RF tag embedded in the cement water mixture can be easily set to a predetermined value by simply embedding a spacer in the cement water mixture in a fresh state. . As a result, even if the position of the reader/writer etc. changes during the execution of estimation processing, the moisture contained in the cement water mixture can be accurately detected by receiving the radio wave signal reflected from the RF tag with the reader/writer etc. It becomes possible to estimate the amount.

In this case, information regarding the embedding depth may be written in the RF tag.

According to the present invention, it is possible to estimate the water content of a cement water kneaded body in any state before hardening or after hardening by a simple method.

1 is a drawing schematically showing an aspect of a first embodiment of a system for estimating the amount of water contained in a cement water kneaded body. It is an example of the functional block diagram of a reader/writer. It is a drawing for explaining the case where the estimation method is executed when the amount of water contained in the cement water kneaded body is small. It is a drawing for explaining the case where the estimation method is executed when the water content contained in the cement water kneaded body is large. 2 is a graph schematically showing the relationship between the amount of water contained in a cement water kneaded body and the intensity of reflected radio waves received by a reader/writer. 2 is a graph schematically showing changes over time in water content and reflected radio wave intensity in fresh concrete or fresh mortar after pouring. 1 is a graph schematically showing changes over time in water content and reflected radio wave intensity in hardened concrete or hardened mortar in the in-use stage. 5 is a graph schematically showing the relationship between the amount of water contained in the cement water kneaded body and the communication distance, similar to FIG. 4. It is a drawing which shows typically the aspect of the second embodiment of the estimation system of the water content contained in a cement water kneaded body. 5 is a graph schematically showing the relationship between the first reflected radio wave intensity, the second reflected radio wave intensity, and the amount of water contained in the cement water kneaded product, similar to FIG. 4. It is a drawing which shows typically the aspect of 3rd embodiment of the estimation system of the water content contained in a cement water kneaded body. It is a drawing which shows typically another aspect of the third embodiment of the estimation system for the amount of water contained in a cement water kneaded body. It is a drawing which shows typically another aspect of the fourth embodiment of the estimation system for the amount of water contained in a cement water kneaded body. It is another example of the functional block diagram of a reader/writer. It is a drawing which shows typically the aspect of another embodiment of the estimation system of the water content contained in a cement water kneaded body. It is a drawing which shows typically the aspect of another embodiment of the estimation system of the water content contained in a cement water kneaded body. These are the results of measuring the relationship between the elapsed time after placing the test mortar and the penetration resistance value. It is a graph showing the relationship between the elapsed time from the start of placing a test mortar in which an RF tag is embedded and the measured reflected radio wave intensity. 16A is a graph showing an enlarged partial area of FIG. 16A. It is a graph which shows the measurement result of the bleeding water with respect to the concrete for a test after pouring.

Regarding the embodiments of the system for estimating the amount of water contained in a cement water kneaded body, the method for estimating the amount of water contained in the cement water kneaded body, and the sensor for estimating the amount of water contained in the cement water kneaded body according to the present invention, The description will be given 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 and the dimensional ratio in the drawings do not necessarily match.

[First embodiment]
As shown in FIG. 1, the system for estimating the amount of water contained in the cement water mixture (hereinafter abbreviated as "estimation system 1") uses an RF tag 5 embedded in the cement water mixture 3 and a reader. It includes a writer 10.

The cement water kneaded body 3 is concrete or mortar in either a pre-cured or post-cured state.

The RF tag 5 has a built-in induction antenna (not shown) and communicates using a radio frequency in a predetermined frequency band. As an example, the RF tag 5 is a plate-shaped RF tag with a resonance frequency of 13.56 MHz, dimensions of 54 mm x 86 mm, and a thickness of 2 mm. The RF tag 5 may be of a non-metal type or a metal-compatible type. In the present invention, the communication frequency band, size, and shape of the RF tag 5 are arbitrary. Such an RF tag 5 is embedded in the cement water kneaded body 3.

When the cement water kneaded body 3 is composed of hardened concrete or mortar, the cement water kneaded body 3 is one in which the RF tag 5 is buried in a fresh state before hardening, and then hardening treatment is performed. It is. Further, when the cement water kneaded body 3 is made of fresh concrete or mortar before hardening, the RF tag 5 is embedded in the cement water kneaded body 3. This embedding step corresponds to step (a).

When estimating the amount of water contained in the cement water kneaded body 3, the worker attaches the reader/writer 10 capable of wireless communication with the RF tag 5 embedded in the cement water kneaded body 3 to the cement water kneaded body 3. Bring it to the site where it is installed. Then, the reader/writer 10 is placed or held near the area where the RF tag 5 is embedded (corresponding to step (b)), and the reader/writer 10 emits a radio signal W1 of a predetermined frequency toward the RF tag 5. Then, the reflected radio wave signal W2 transmitted from the RF tag 5 is received (corresponding to step (c)). Note that a detailed explanation of this step (c) will be given later.

The reader/writer 10 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 reflected radio signal W2 is installed. do not have. In this embodiment, the case where the "reader/writer 10" is used will be explained as an example, but any device that can communicate with at least the RF tag 5 is sufficient. It does not matter if it is a so-called "leader" that does not have one.

FIG. 2 is an example of a functional block diagram of the reader/writer 10 in this embodiment. The reader/writer 10 includes a communication section 11, a display output section 12, and an estimation device 20. Note that, as will be described later with reference to FIG. 13, the estimation device 20 may be configured as a separate device from the reader/writer 10 without being built into the reader/writer 10.

The communication unit 11 is an interface for performing wireless communication with the RF tag 5. The display output unit 12 is a functional means that performs predetermined display arithmetic processing and displays the processed content on a monitor (not shown). The estimation device 20 is a processing device that estimates the amount of water contained in the cement water kneaded body 3 through arithmetic processing based on the reflected radio wave signal W2 transmitted from the RF tag 5 in the communication section 11. and a storage section 22. The storage unit 22 is composed of a storage medium such as a flash memory or a hard disk, and has predetermined information, which will be described later, recorded therein. The estimation processing section 21 is a processing section that performs arithmetic processing based on the reflected radio wave signal W2 transmitted from the RF tag 5 and the information recorded in the storage section 22, and is composed of dedicated hardware or software.

How the intensity of the reflected radio signal W2 changes depending on the amount of water contained in the cement water kneaded body 3 will be explained with reference to FIGS. 3A and 3B. 3A corresponds to a case where the amount of water contained in the cement water kneaded body 3 is relatively small, and FIG. 3B corresponds to a case where the amount of water contained in the cement water kneaded body 3 is large compared to the situation in FIG. 3A. Compatible. In FIGS. 3A and 3B, the difference in the amount of water contained in the cement water kneaded body 3 is schematically expressed by the density of hatching attached to the cement water kneaded body 3.

As described above, when the radio signal W1 is transmitted from the reader/writer 10 toward the RF tag 5, the surface 3a of the cement water kneaded body 3 (hereinafter appropriately referred to as the "cement water kneaded body surface 3a") and the reader As long as the separation distance h10 from the writer 10 is not too far, the radio wave signal W1 is received on the RF tag 5 side, and the reflected radio wave signal W2 is transmitted toward the reader/writer 10. However, since water exhibits conductivity, the intensity of the reflected radio wave signal W2 decreases depending on the amount of water present in the propagation path of the reflected radio wave signal W2.

As described above, FIG. 3B simulates a situation where the amount of water contained in the cement water kneaded body 3 is greater than that in FIG. 3A. This means that in the state shown in FIG. 3B, the amount of water contained in the region 3b between the RF tag 5 and the cement water kneaded body surface 3a, in other words, the amount of water present in the propagation path of the reflected radio wave signal W2, This means that there are more cases than the state shown in FIG. 3A. That is, if the intensity of the reflected radio wave signal W2 received by the reader/writer 10 in the state of FIG. 3A is E2x, the reflected radio wave signal W2 received by the reader/writer 10 in the state of FIG. The strength of the radio signal W2 is E2y, which is lower than E2x.

As described above, the amount of water contained in the cement water kneaded body 3 (the amount of water contained V3) is taken on the horizontal axis, and the intensity E2 of the reflected radio wave signal W2 (hereinafter appropriately referred to as "reflected radio wave intensity E2") is taken on the vertical axis. When plotted in a graph, the two show a negative correlation as shown in FIG. More specifically, the reflected radio wave intensity E2 is substantially inversely proportional to the water content V3. In addition, FIG. 4 is a graph shown schematically to the last, and the intention is to limit the reflected radio wave intensity E2 to be inversely proportional to the water content V3 in the cement water kneaded body 3 in a strict sense. There isn't.

When the cement water kneaded body 3 is fresh concrete or fresh mortar, a hydration reaction progresses over time and free water decreases. Such a phenomenon does not occur at a specific location inside the cement water kneaded body 3, but occurs throughout the cement water kneaded body 3. As a result, the content throughout the cement water kneaded body 3 is determined by the value of the reflected radio wave intensity E2 (E2x, E2y), which depends on the amount of water in the region 3b between the RF tag 5 and the cement water kneaded body surface 3a. It can be seen that the water content V3 can be estimated.

FIG. 5A is a graph schematically showing changes over time in water content V3 and reflected radio wave intensity E2 in fresh concrete or fresh mortar after pouring. As shown in FIG. 5A, as a result of the hydration reaction progressing over time after pouring, the water content V3 decreases, so the reflected radio wave intensity E2 received by the reader/writer 10 shows an increasing tendency over time. .

On the other hand, when the cement-water kneaded body 3 is hardened concrete or hardened mortar, that is, when the cement-water kneaded body 3 is in the in-service stage, the water content does not substantially change due to the hydration reaction. The cause of such a change in the amount of water contained in the cement water kneaded body 3 is generally caused by rainwater or dew condensation. Moisture derived from rainwater and condensation permeates into the cement water kneaded body 3 from the surface 3a side of the cement water kneaded body in the depth direction, and this permeation phenomenon occurs throughout the surface direction of the cement water kneaded body 3a. arise. In other words, even in this case, the cement water It is possible to estimate the water content V3 throughout the kneaded body 3.

FIG. 5B is a graph schematically showing changes over time in the water content V3 and the reflected radio wave intensity E2 in hardened concrete or hardened mortar in the in-use stage. As shown in FIG. 5B, when the cement water kneaded body 3 is in the service stage, the water content V3 basically does not change over time and remains almost constant. Then, at a certain timing (time periods t1 and t2), when moisture permeates into the cement water mixture 3 due to rainwater, dew condensation, etc., the moisture content temporarily increases, and the reflection received by the reader/writer 10 Radio field intensity E2 temporarily decreases.

As described above, according to the estimation system 1 of the present embodiment, in a wide range of situations from the construction stage where the concrete and mortar constituting the cement water mixture 3 have not yet sufficiently hardened to the service stage after hardening, It becomes possible to estimate the water content V3 contained in the cement water kneaded body 3.

Specifically, as shown in FIG. 4, since the water content V3 in the cement water kneaded body 3 and the reflected radio wave intensity E2 show a certain correlation, information that defines this correlation (hereinafter referred to as , referred to as "correlation information") may be recorded in advance in the storage unit 22. As a result, the estimation processing unit 21 collates the information regarding the reflected radio wave intensity E2 received by the communication unit 11 with the correlation information recorded in the storage unit 22, thereby determining the water content V3 in the cement water kneaded body 3. The estimated value of can be calculated. That is, the reader/writer 10 measures the reflected radio wave intensity E2 (corresponding to step (c)), and estimates the water content V3 based on this reflected radio wave intensity E2 and the correlation information (step (d)). correspondence).

This correlation information only needs to describe the relationship between the water content V3 and the reflected radio wave intensity E2, and is not limited to the manner in which it is described. That is, the correlation information may be written in the form of a data table or in the form of a function.

Further, as the correlation information recorded in the storage unit 22, data measured in advance using a specimen made of the same type of material and composition as the cement water kneaded body 3 can be used. In this case, as the value of the water content V3, for example, a value measured using the following method can be adopted.

If the specimen is a cement-water mixture after hardening (hardened concrete, hardened mortar, etc.), as the specimen changes from a wet state to a dry state, or vice versa, from a wet state to a dry state. The measured value of the changing mass can be used as the water content V3. Then, correlation information can be obtained from the relationship between the mass measurement data V3 and the reflected radio wave intensity measurement data E2.

If the specimen is a cement water mix before hardening (fresh concrete, fresh mortar, etc.), the water content is estimated from the measured value of the measurement index that corresponds to the change in moisture over time during the hardening process of the specimen. The amount may be V3. For example, the amount of bleeding water can be used as a measurement index, and the amount of bleeding water can be measured over time using a test method (for example, a method based on JIS A 1123), and the water content can be determined from this measurement value. Estimate the value of V3. Correlation information can then be obtained from the relationship between this estimated value and the measured data of reflected radio wave intensity.

Bleeding water is the water that rises to the surface of concrete after fresh concrete is placed. Based on the amount of this bleeding water and the bleeding rate, which is the amount of bleeding water expressed as a percentage of the total water amount in the sample, the water content is Since the value of the amount V3 can be estimated, the amount of bleeding water can be used as a measurement index. Note that the estimated value of the water content V3 may be an estimated value of the water content per unit area, or may be an estimated value of the ratio to the amount of water mixed. The manner in which the amount of bleeding water changes after fresh concrete is placed will be described later with reference to Examples.

It should be noted for confirmation that this specimen is only used to obtain information to be recorded in the storage unit 22, and is not used when performing estimation processing.

(Another aspect)
By the way, the method described above estimates the water content V3 based on the value of the intensity of the reflected radio wave signal W2 (reflected radio wave intensity E2), and in other words, it serves as the basis for estimating the water content V3. The index value was the reflected radio wave intensity E2. However, some reader/writers 10 cannot measure the intensity value even if they have the function of receiving the reflected radio wave signal W2.

In such a case, while changing the distance h10 (see FIG. 3A) between the reader/writer 10 and the cement water kneaded body surface 3a, the maximum value of the distance h10 (hereinafter referred to as " (referred to as "separation distance upper limit threshold h10max") may be used as an index value that is the basis for estimating the water content V3.

FIG. 6 is a graph schematically showing the relationship between the water content V3 and the communication distance d2, similar to FIG. 4. Note that the communication distance d2 here refers to the upper limit threshold of the separation distance between the reader/writer 10 and the RF tag 5 that allows the reader/writer 10 to detect the reflected radio wave signal W2.

If the intensity E2 (reflected radio wave intensity E2) of the reflected radio wave signal W2 transmitted from the RF tag 5 after passing through the cement water kneaded body 3 is relatively high, the reader/writer 10 is The reader/writer 10 can detect the reflected radio wave signal W2 even if it is relatively far away from the tag 5. On the other hand, when the reflected radio wave intensity E2 is relatively low, the reader/writer 10 cannot detect the reflected radio wave signal W2 unless the reader/writer 10 is brought close to the RF tag 5.

In other words, the reflected radio wave intensity E2 and the communication distance d2 have a positive correlation, and more specifically, they can be said to have a substantially proportional relationship. Comparing FIG. 6 and FIG. 4, the only difference is whether the vertical axis is the reflected radio wave intensity E2 or the communication distance d2, and the comparative relationship with the water content V3 is similar.

The communication distance d2 corresponds to the sum of the separation distance upper limit threshold value h10max mentioned above and the burial depth of the RF tag 5 in the cement water kneaded body 3. The depth of embedding the RF tag 5 in the cement water kneaded body 3 does not change at the same site. Therefore, it is possible to estimate the water content V3 substantially based on the separation distance upper limit threshold h10max.

In the case of this method, even if information defining the correlation between the water content V3 and the separation distance upper limit threshold h10max (corresponding to the above-mentioned "correlation information") is recorded in the storage unit 22, I do not care. As the correlation information in this case, for example, information obtained by the same method as in the case of obtaining the correlation information between the water content V3 and the reflected radio wave intensity E2 can be used.

Further, correlation information between the water content V3 and the communication distance d2 may be recorded in the storage unit 22. In this case, information about the burial depth of the RF tag 5 in the cement water kneaded body 3 is recorded in advance in the storage unit 22, and the target After calculating the communication distance d2 of the cement water kneaded body 3, the water content V3 can be estimated from the correlation information. Note that, as will be described later with reference to FIG. 11, if information regarding the embedding depth is stored in advance on the RF tag 5 side, it is not necessary to record the information regarding the embedding depth in the storage unit 22. Instead, the reader/writer 10 side only needs to receive information about the burial depth when receiving the reflected radio wave signal W2.

Note that even if the reader/writer 10 is configured to be able to detect the reflected radio wave intensity E2, the estimating device 20 may estimate the water content V3 based on the separation distance upper limit threshold h10max.

[Second embodiment]
A second embodiment of the estimation system 1 will be described with reference to FIGS. 7 and 8. In addition, in FIG. 7, for convenience of illustration, the illustration of the radio wave signal W1 among the radio wave signals (E1, E2) is omitted, and only the reflected radio wave signal W2 is illustrated. Also in the following drawings, illustration of the radio signal W1 may be omitted.

In the estimation system 1 described above in the first embodiment, when estimating the water content V3 based on the reflected radio wave intensity E2, the distance h10 between the reader/writer 10 and the cement water kneaded body surface 3a (FIG. 3A, 3B) must be kept at a predetermined value as much as possible. This is because if the separation distance h10 changes, the reflected radio wave intensity E2 changes, and there is a possibility that the water content V3 cannot be estimated correctly.

However, depending on circumstances such as the surrounding environment of the cement water kneaded body 3 to be measured, it may be difficult to arrange the reader/writer 10 while maintaining the separation distance h10 at a predetermined value.

The estimation system 1 of the present embodiment is configured to be able to accurately estimate the water content V3 of the cement water kneaded body 3 even if the position of the reader/writer 10 cannot be fixed, and It includes a first RF tag 5a and a second RF tag 5b that are buried at different depths. More specifically, as shown in FIG. 7, the first RF tag 5a is buried in the cement water kneaded body 3 at a buried depth h5a, and the first RF tag 5a is buried at a buried depth h5b which is deeper than the buried depth h5a. A second RF tag 5b is embedded at the position.

When the cement water kneaded body 3 is composed of hardened concrete or mortar, the first RF tag 5a and the second RF tag 5a are placed at different buried depths in the fresh state before hardening. After the RF tag 5b was embedded, a curing process was performed. In addition, when the cement water kneaded body 3 is composed of fresh concrete or mortar before hardening, a first RF tag 5a and a second RF tag are placed at different buried depths in the cement water kneaded body 3. 5b is buried (corresponding to step (a)).

The reader/writer 10 receives reflected radio wave signals (W2a, W2b) from the RF tags (5a, 5b), respectively (corresponding to step (c)). Since the first RF tag 5a is buried in a position closer to the surface 3a of the cement water kneaded body 3 than the second RF tag 5b, the intensity E2a of the reflected radio wave signal W2a from the first RF tag 5a is different from that of the second RF tag 5b. The intensity is higher than the intensity E2b of the reflected radio wave signal W2b from the RF tag 5b. In the following, the intensity E2a of the reflected radio wave signal W2a from the first RF tag 5a will be referred to as "first reflected radio wave intensity E2a", and the intensity E2b of the reflected radio wave signal W2b from the second RF tag 5b will be referred to as "second reflected radio wave intensity E2a". Strength E2b".

FIG. 8 is a graph schematically showing the relationship between the first reflected radio wave intensity E2a, the second reflected radio wave intensity E2b, and the water content V3 in the cement water kneaded body 3, similar to FIG. 4.

The difference value dE2 between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b tends to become smaller as the water content in the cement water kneaded body 3 increases. As the water content in the cement water kneaded body 3 increases, the amount of water present in the area between the first RF tag 5a and the cement water kneaded body surface 3a and the second RF tag 5b increase. This is because the difference in the amount of water existing in the area between the water and the surface 3a of the cement water kneaded body becomes smaller.

Therefore, the difference value dE2 between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b shows a negative correlation with the value of the water content V3. This difference value dE2 hardly or not changes at all even if the distance h10 between the reader/writer 10 and the cement water kneaded body surface 3a changes. Therefore, the correlation between the difference value dE2 and the water content V3 is recorded in the storage unit 22 of the estimation device 20, and the estimation processing unit 21 calculates the intensity of each reflected radio wave (E2a, E2b) received by the communication unit 11. By calculating the difference and comparing it with the correlation read from the storage unit 22, the water content V3 in the cement water kneaded body 3 can be estimated (corresponding to step (d)).

(Another aspect)
Another aspect of the estimation system of this embodiment will be explained.

<1> In this embodiment, the water content V3 in the cement water kneaded body 3 is estimated based on the difference value dE2 between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b. The water content V3 in the cement water kneaded body 3 may be estimated based on a reference value obtained by performing a predetermined calculation on the value dE2. That is, in this embodiment, the first reflected radio wave intensity E2a from the first RF tag 5a is defined as the "first index value", and the second reflected radio wave intensity E2b from the second RF tag 5b is defined as the "second index value". The water content V3 is estimated based on the difference value between these index values or a value uniquely determined based on the difference value, or the ratio between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b.

<2> In the estimation system 1 of this embodiment, the RF tags 5 may be buried in three or more different buried depths in the cement water kneaded body 3.

<3> The first RF tag 5a is set so that the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b received on the reader/writer 10 side are different when the first RF tag 5a is not embedded in the cement water kneaded body 3. and the second RF tag 5b may be selected. According to this configuration, as schematically shown in FIG. 8, there is a difference between the displacement tendency of the first reflected radio wave intensity E2a with respect to the water content V3 and the displacement tendency of the second reflected radio wave intensity E2b with respect to the water content V3. Since it becomes easier to determine the amount of water contained in the water content V3 based on the difference value dE2, the accuracy of estimating the water content V3 based on the difference value dE2 is improved.

[Third embodiment]
A third embodiment of the estimation system 1 will be described with reference to FIG. 9. Similarly to the second embodiment, the estimation system 1 of this embodiment is also configured to be able to accurately estimate the water content V3 of the cement water kneaded body 3 even when the position of the reader/writer 10 cannot be fixed. The estimation system 1 of this embodiment includes a plurality of RF tags (5a, 5b) embedded in the cement water kneaded body 3 similarly to the second embodiment. However, the first RF tag 5a and the second RF tag 5b have different water absorption rates in their installed areas.

In the example shown in FIG. 9, a plurality of RF tags (5a, 5b) are installed within an integrated spacer 30. This spacer 30 has a first region 31 made of a material with a water absorption rate lower than that of the cement water kneaded body 3 and a second region 32 made of a material showing a water absorption rate equivalent to that of the cement water kneaded body 3. has been done. As an example, the first region 31 is made of UFC (Ultra High Strength Fiber Reinforced Concrete), ceramics, or resin such as polyethylene or polypropylene. Further, the second region 32 is made of mortar or concrete, similar to the cement water kneaded body 3. In the example shown in FIG. 9, the first region 31 of the spacer 30 corresponds to the "tag protector".

The first RF tag 5a and the second RF tag 5b are installed at approximately the same buried depth. Note that "almost the same" means that the intensity E2a of the reflected radio wave signal W2a from the first RF tag 5a (first reflected radio wave intensity E2a) and the intensity E2b of the reflected radio wave signal W2b from the second RF tag 5b (second This includes the case where the difference from the reflected radio wave intensity E2b) is within a range that can be approximated by depending substantially only on the difference in water absorption. Specifically, the difference in the buried depth between the first RF tag 5a and the second RF tag 5b is allowed to be within 10% of the buried depth.

When the cement water kneaded body 3 is composed of hardened concrete or mortar, the first RF tag 5a is installed in the first region 31 of the cement water kneaded body 3 in a fresh state before hardening. At the same time, after a spacer 30 having a second RF tag 5b installed therein was buried in the second region 32, a curing process was performed. In addition, when the cement water kneaded body 3 is composed of fresh concrete or mortar before hardening, a spacer 30 in which the first RF tag 5a and the second RF tag 5b are installed inside the cement water kneaded body 3 is buried (corresponding to step (a)).

The reader/writer 10 receives reflected radio wave signals (W2a, W2b) from the RF tags (5a, 5b), respectively (corresponding to step (c)). Even if the cement water kneaded body 3 contains water, the first RF tag 5a is installed in the first region 31 which has a lower water absorption rate than the material of the cement water kneaded body 3. - The amount of water between the RF tag 5a and the surface 3a of the cement water kneaded body is relatively small. On the other hand, since the second RF tag 5b is installed in the second region 32 made of a material having the same water absorption rate as the cement water kneaded body 3, the second RF tag 5b and the cement water kneaded body surface 3a The amount of moisture between the first RF tag 5a and the surface 3a of the cement water kneaded body is larger than that between the first RF tag 5a and the surface 3a of the cement water kneaded body.

As a result, the intensity E2a of the reflected radio wave signal W2a from the first RF tag 5a (first reflected radio wave intensity E2a) is greater than the intensity E2b of the reflected radio wave signal W2b from the second RF tag 5b (second reflected radio wave intensity E2b). It also becomes more expensive. The difference between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b originates from the difference between the water absorption rate ε1 of the first region 31 and the water absorption rate ε2 of the second region 32. In other words, the difference between the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b is the ratio between the water absorption rate ε1 of the first region 31 and the water absorption rate ε2 of the second region 32, and the difference between the water absorption rate ε1 of the first region 31 and the water absorption rate ε2 of the second region 32, and It is determined by the water content V3.

For example, when the water absorption rate ε1 of the first region 31 can be considered to be approximately 0, the content contained in the cement water kneaded body 3 is determined by the ratio jE2 of the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b. The water content V3 can be estimated. In this case, the correlation between the ratio jE2 and the water content V3 is recorded in the storage unit 22 of the estimation device 20, and the estimation processing unit 21 calculates each reflected radio wave intensity (E2a, E2a, By calculating the ratio of E2b) and comparing it with the correlation read from the storage unit 22, the water content V3 in the cement water kneaded body 3 can be estimated (corresponding to step (d)).

Furthermore, even if the water absorption rate ε1 of the first region 31 cannot be approximated to 0, since each water absorption rate (ε1, ε2) is known, the difference in water absorption rate between the first region 31 and the second region 32 Accordingly, it is possible to define the water content V3 as a function of the first reflected radio wave intensity E2a and the second reflected radio wave intensity E2b. In this case, the function is recorded in the storage unit 22 of the estimation device 20, and the estimation processing unit 21 reads out the values of each reflected radio wave intensity (E2a, E2b) received by the communication unit 11 from the storage unit 22. The water content V3 in the cement water kneaded body 3 can be estimated by applying the above function to the calculation (corresponding to step (d)).

The second RF tag 5b does not necessarily need to be installed on the spacer 30. That is, as shown in FIG. 10, only the first RF tag 5a is installed in a spacer 30 made of a material with a lower water absorption than the cement water kneaded body 3, and then this spacer 30 is placed inside the cement water kneaded body 3. It may be buried within 3. In this case, the second RF tag 5b is buried in the cement water mixture 3 at a position outside the spacer 30 and at approximately the same buried depth as the first RF tag 5a. In the case of the configuration shown in FIG. 10, the spacer 30 itself corresponds to the "tag protector".

Note that the spacer 30 equipped with the first RF tag 5a and the second RF tag 5b shown in FIG. 9 or the spacer 30 equipped with the first RF tag 5a shown in FIG. This corresponds to an example of "sensor for estimating the amount of moisture contained in water".

[Fourth embodiment]
A fourth embodiment of the estimation system 1 will be described with reference to FIGS. 11 and 12. Similarly to the second embodiment, the estimation system 1 of this embodiment is also configured to be able to accurately estimate the water content V3 of the cement water kneaded body 3 even if the position of the reader/writer 10 cannot be fixed.

The estimation system 1 of this embodiment includes a spacer 30 buried in the cement water kneaded body 3 similarly to the third embodiment. However, the water absorption rate of the spacer 30 is not limited. Moreover, in the estimation system 1 of this embodiment, the RF tag 5 installed in the spacer 30 may be alone.

The spacer 30 is provided to adjust the cover thickness of concrete or mortar. Therefore, if the RF tag 5 is installed at a predetermined position within the spacer 30, the distance between the cement water kneaded body surface 3a and the RF tag 5, that is, the burial depth h5 of the RF tag 5 can be adjusted from the stage before construction. Recognizable. That is, on the RF tag 5 side, it is possible to write information on the buried depth h5 (depth information).

In other words, when the cement water kneaded body 3 is made of hardened concrete or mortar, the cement water kneaded body 3 is in a fresh state before hardening, and the RF tag 5 on which information about the burial depth h5 is written is attached. After the spacer 30 with the spacer 30 installed therein was buried, a curing process was performed. In addition, when the cement water mixture 3 is made of fresh concrete or mortar before hardening, a spacer 30 is buried with an RF tag 5 on which information about the burial depth h5 is written ( Corresponding to step (a)).

The reader/writer 10 receives the reflected radio wave signal W2 from the RF tag 5 (corresponding to step (c)). At this time, the reader/writer 10 also reads information about the burial depth h5 recorded on the RF tag 5.

The reader/writer 10 of this embodiment is equipped with a distance measuring sensor 23 as shown in FIG. The separation distance h10 can be measured.

Here, α is a coefficient that varies depending on the communication distance of the reflected radio wave signal W2 in the air (separation distance h10), and coefficient α varies depending on the communication distance of the reflected radio wave signal W2 in the dry cement water mixture 3 (burying depth h5). The reflected radio wave intensity E2 can be evaluated by the following equation (1), where β is a coefficient that changes the reflected radio wave signal W2 and γ is a coefficient that varies depending on the water content V3 in the cement water kneaded body 3.
E2 = α・h10+(β・h5)・γ…(1)

That is, the value of γ defined by the function of the water content in the cement water kneaded body 3 is calculated by the following equation (2).
γ = (E2 - α・h10)/(β・h5) …(2)

The storage unit 22 stores in advance the relationship between the separation distance h10 and the coefficient α, the relationship between the burial depth h5 and the coefficient β, the relationship between the water content V3 of the cement water kneaded body 3 and the coefficient γ, and the above formula (2). Information regarding the evaluation formula corresponding to each is recorded. As described above, the estimation device 20 side can detect information about the separation distance h10 and the burial depth h5. Therefore, the estimation processing unit 21 can calculate the values of the coefficient α and the coefficient β from the information regarding the separation distance h10 and the burial depth h5. Then, the estimation processing unit 21 calculates the coefficient γ by substituting the values of the reflected radio wave intensity E2, the coefficient α, and the coefficient β into equation (2), and then calculates the coefficient γ and calculates the coefficient γ. From the relationship of the coefficient γ, the water content V3 corresponding to the calculated value of γ can be derived.

The above formula (2) is described as an example for explanation purposes only, and calculations do not necessarily have to be based on this formula. The estimation system 1 of this embodiment uses information regarding the burial depth h5 read from the RF tag 5, reflected radio wave intensity E2, and information regarding the separation distance h10 between the reader/writer 10 and the cement water kneaded body surface 3a. This includes a method of calculating an estimated value of the water content V3 of the cement water kneaded body 3 using the above method.

Moreover, the method of measuring the separation distance h10 between the reader/writer 10 and the cement water kneaded body surface 3a is arbitrary. In other words, the reader/writer 10 does not need to be equipped with a function to measure the separation distance h10.

Note that the spacer 30 equipped with the first RF tag shown in FIG. 11 corresponds to an example of the "sensor for estimating the amount of water contained in the cement water kneaded body" according to the present invention.

[Another embodiment]
Another embodiment will be described below.

<1> As shown in FIG. 13, the estimation device 20 may be configured as a separate device from the reader/writer 10. In this case, information regarding the strength of the reflected radio wave signal W2 received by the reader/writer 10 is transmitted to the estimation device 20 via wire or wirelessly, and calculation processing is performed on the estimation device 20 side based on the received information. Then, the water content V3 is estimated. In the example shown in FIG. 13, the estimation device 20 includes an information output section 24 for outputting the calculation result by the estimation processing section 21. The information output unit 24 may be a communication interface, or may be a processing means for display processing for displaying on a monitor (not shown).

<2> In the above embodiment, the RF tags 5 (5a, 5b) are non-metal compatible RF tags, but when a metal material is present near the back side, for example, when fixing the spacer 30 to a reinforcing bar, etc. In this case, the RF tags 5 (5a, 5b) may be RF tags compatible with metal (metal tags).

<3> In each of the embodiments described above, the estimation system 1 may further include a function of notifying the user of the estimated moisture content. As an example, the display output section 12 mounted on the reader/writer 10 may display the moisture content estimated by the estimation processing section 21. Further, information regarding the estimated moisture content may be transmitted to a server or a smartphone through a communication means (not shown). Furthermore, an audio signal for notification may be outputted through an audio output means (speaker, etc.) not shown. Based on the information regarding the moisture content and the notification audio signal, the user can, for example, grasp the finishing timing of the above-mentioned floor concrete at the construction stage and the risk of occurrence of reinforcing steel corrosion during the common use stage of the concrete structure. I can do it.

Note that in this case, the information to be notified is not limited to the estimated moisture content value itself. As an example, the estimating device 20 may be configured to determine whether or not the finishing time in the floor concrete construction stage has been reached based on the estimated moisture content, and to notify the result of this determination. As another example, the estimating device 20 may determine the degree of risk of occurrence of reinforcing steel corrosion in the shared stage of the concrete structure based on the estimated moisture content, and the determination result may be notified. As this determination method, for example, a threshold value of moisture content for determining that the finishing time has been reached is stored in advance in the storage unit 22, and when the actually estimated moisture content reaches this threshold value, the estimation processing unit Although it is possible to adopt a method of determining that 21 has reached the finishing time, the method is not limited to this method.

<4> In the second embodiment described above, two types of RF tags (5a, 5b) with different buried depths are used, and the reflected radio wave signal (W2a) transmitted from each of these RF tags (5a, 5b) is used. , W2b) and a value based on the ratio, the water content V3 is estimated. On the other hand, by providing a plurality of communication units 11 at different positions on the reader/writer 10 side, it is also possible to provide multiple types of separation distances between each communication unit 11 and the RF tag 5 (for example, FIG. reference).

FIG. 14 is a drawing schematically showing the configuration of the estimation system 1 of this other embodiment. The reader/writer 10 is equipped with a plurality of communication units (11a, 11b). The communication units (11a, 11b) are, for example, antennas, and at least one of these antennas may be externally attached. These communication units (11a, 11b) are installed at positions where the distances from the cement water kneaded body surface 3a can be made different from each other. More specifically, these communication units (11a, 11b) are located at different distances (h11a, h11b) from the surface 10a facing the cement water kneaded body 3 to be measured on the surface of the reader/writer 10. will be installed in According to the example in FIG. A09, the distance between the communication section 11a and the surface 3a of the cement water kneaded body corresponds to the sum of h10 and h11a, and the distance between the communication section 11b and the surface 3a of the cement water kneaded body is: It corresponds to the total value of h10 and h11b.

In the case of this configuration, the reader/writer 10 receives reflected radio wave signals (W2a, W2b) from the RF tag 5 in two installed communication units (11a, 11b), respectively. The difference value or ratio of the intensities (E2a, E2b) of these reflected radio wave signals is such that even if the distance h10 between the surface of the reader/writer 10 and the cement water kneaded body surface 3a changes, the content in the cement water kneaded body 3 The value depends on the moisture content. As a result, even if there are circumstances in which the separation distance h10 cannot be maintained at a predetermined value during measurement, the water content V3 in the cement water kneaded body 3 can be estimated as in the above embodiment.

The following description will be made with reference to examples.

[Test 1]
Test mortars made of the materials shown in Tables 1 and 2 below were poured, and the hardening time was measured while measuring the penetration resistance value over a predetermined period of time using a method based on JIS A 1147. The results of this evaluation are shown in FIG. In addition, in FIG. 15, the time point when the penetration resistance value reached 3.5 N/mm ² is described as "beginning", and the time point when it reached 28.0 N/mm ² is described as "end". In Table 1, W/C refers to the water-cement ratio, and S/C refers to the sand-cement ratio.

Next, mortar made of the material shown in Table 1 above is placed at a position with a buried depth of 4 cm, with the RF tag 5 having dimensions of 25 mm wide x 9 mm long x 3 mm thick buried, and the reader is The reflected radio wave signal W2 was received by the writer 10, and the intensity E2 (reflected radio wave intensity E2) was measured. The reader/writer 10 used had a corresponding signal frequency of 920 MHz band and an output of 250 mW. The measurement results are shown in FIGS. 16A and 16B.

That is, in this example, the cement water kneaded body 3 whose water content is to be measured is simulated by fresh mortar.

Note that during the measurement, the reflected radio wave intensity E2 was measured with the reader/writer 10 installed at three different positions with different distances h10 from the mortar surface: 90 mm, 120 mm, and 150 mm. Further, FIG. 16B is an enlarged view of a part of the time period in FIG. 16A.

According to FIG. 16B, it is confirmed that the reflected radio wave intensity E2 gradually increases regardless of the separation distance h10 from the time when the concrete is placed until the time when it is finished. This indicates that as the hydration reaction of the cement progresses and hardening progresses, the free water decreases, and the reflected radio wave intensity E2 increases. This result shows that the water content V3 in the cement water kneaded body 3 can be estimated based on the reflected radio wave intensity E2.

Moreover, according to FIG. 16A, it is confirmed that the reflected radio wave intensity E2 further increases after the termination. This indicates that the hydration reaction further progresses and the water content V3 in the cement water kneaded body 3 (here mortar) tends to decrease.

From the above results, it is confirmed that the water content V3 in the cement water kneaded body 3 can be estimated based on the reflected radio wave intensity E2.

[Test 2]
Test concrete made of the materials shown in Tables 3 and 4 below was poured, and the amount of bleeding water was measured by a method based on JIS A 1123. The evaluation results are shown in FIG. 17 and Table 5. FIG. 17 is a graph showing the relationship between the cumulative amount of bleeding water and the elapsed time. In Table 4, s/a refers to the ratio of the mass of fine aggregate to the total mass (fine aggregate ratio), and the amount of admixtures (Ad1, Ad2) is expressed as a percentage of the mass of cement. ing.

According to FIG. 17, it is confirmed that the amount of bleeding water tends to increase over time from the time of pouring to the time of completion. This indicates that some of the free water is floating on the concrete surface as time passes. As described above, as free water decreases, the reflected radio wave intensity E2 increases. Therefore, information on the amount of bleeding water and reflected radio wave intensity measured at each elapsed time is used as the above-mentioned correlation information, and based on this correlation information and the actually measured reflected radio wave intensity E2, the amount of bleeding water in the cement water kneaded body 3 is calculated. It can be seen that the water content V3 can be estimated.

1: Estimation system 3: Cement water kneaded body 3a: Cement water kneaded body surface 3b: Region 5: RF tag 5a: First RF tag 5b: Second RF tag 10: Reader/writer 10a: Reader/writer surface 11: Communication section 12 :Display output section 20:Estimation device 21:Estimation processing section 22:Storage section 23:Distance sensor 24:Information output section 30:Spacer 31:First area 32:Second area W1:Radio signal W2, W2a, W2b: Reflected radio wave signals E2, E2a, E2b: Reflected radio wave intensity

Claims (9)

A system for estimating the amount of water contained in a cement water mixture belonging to any one of fresh concrete after placement, hardened concrete, fresh mortar after placement, or hardened mortar, the system comprising:
an RF tag embedded in the cement water kneaded body;
a reader or reader/writer capable of transmitting and receiving radio signals to and from the RF tag;
Based on an index value of at least one of the intensity value of the radio wave signal received by the reader or reader/writer, or the upper limit threshold of the separation distance between the reader/reader/writer and the cement water kneaded body that can detect reception of the radio signal. and an estimating device for estimating the amount of water contained in the cement water kneaded body ,
The estimating device includes a storage section in which information regarding the correlation between the index value and the amount of water contained in the cement water kneaded body is recorded, and reads out the information regarding the correlation from the storage section and calculates the amount of water contained in the cement water kneaded body. A system for estimating the amount of water contained in the cement water kneaded material, characterized in that the amount of water contained in the cement water kneaded material is estimated in accordance with the index value . The RF tag includes a first RF tag and a second RF tag embedded at different depths in the cement water kneading body,
The estimation device has a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. Estimating the amount of water contained in the cement water kneaded body according to claim 1 , characterized in that the amount of water contained in the cement water kneaded body is estimated based on a comparison result with a certain second index value. system. A tag protector is embedded in the cement water kneaded body and is made of a material having a lower water absorption rate than the cement water kneaded body,
The RF tag includes a first RF tag embedded within the tag protector and a second RF tag embedded within the cement water mixer at a location outside the tag protector;
The estimation device has a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. Estimating the amount of water contained in the cement water kneaded body according to claim 1 , characterized in that the amount of water contained in the cement water kneaded body is estimated based on a comparison result with a certain second index value. system. a spacer embedded in the cement water kneading body and having the RF tag fixed thereto;
The RF tag records depth information regarding the burial depth from the surface of the cement water kneaded body,
The reader or reader/writer receives the depth information together with the intensity value of the radio signal from the RF tag,
The estimating device calculates the cement water kneading body based on the intensity value of the radio signal received by the reader or reader/writer, the depth information, and the separation distance between the reader or reader/writer and the cement water kneading body. The system for estimating the amount of water contained in a cement water kneaded body according to claim 1 , characterized in that the amount of water contained in the cement water kneaded body is estimated. The system for estimating the amount of water contained in a cement water kneaded body according to any one of claims 1 to 4 , wherein the estimating device is installed in the reader or reader/writer. A method for estimating the amount of water contained in a cement water mixture belonging to any one of fresh concrete after placement, hardened concrete, fresh mortar after placement, or hardened mortar, the method comprising:
a step (a) of embedding an RF tag in the cement water kneaded body;
a step (b) of arranging a reader or reader/writer capable of transmitting and receiving radio signals to and from the RF tag at a predetermined position outside the cement water kneaded body;
Measure an index value of at least one of the intensity value of the radio wave signal received by the reader or reader/writer, or the upper limit threshold of the separation distance between the reader/reader/writer and the cement water kneaded body that can detect the reception of the radio signal. step (c) of
a step (d) of estimating the amount of water contained in the cement water kneaded body based on the index value ,
The step (d) reads out information regarding the correlation between the stored index value and the amount of water contained in the cement water kneaded body, and reads the information corresponding to the index value measured in the step (c). 1. A method for estimating the amount of water contained in a cement-water kneaded material, the method comprising: estimating the amount of water contained in the cement-water kneaded material. The step (a) includes a step of embedding a first RF tag and a second RF tag at different burial depths in the cement water kneaded body in a fresh state,
The step (c) includes a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. and a second index value that is a value,
The step (d) includes a step of estimating the amount of water contained in the cement water kneaded body based on a comparison result between the first index value and the second index value. 6. The method for estimating the amount of water contained in a cement water kneaded body, as described in 6 . The step (a) includes a first RF tag embedded in a tag protector made of a specific material having a lower water absorption rate than the cement water kneaded body, and a second RF tag disposed outside the tag protector. embedding the tag together with the tag protector in the cement water kneading body in a fresh state,
The step (c) includes a first index value that is the index value based on the intensity value of the radio signal from the first RF tag, and a first index value that is the index value based on the intensity value of the radio signal from the second RF tag. and a second index value that is a value,
The step (d) includes a step of estimating the amount of water contained in the cement water kneaded body based on a comparison result between the first index value and the second index value. 6. The method for estimating the amount of water contained in a cement water kneaded body, as described in 6 . The RF tag records depth information regarding the burial depth from the surface of the cement water kneaded body,
The step (a) includes a step of embedding the RF tag in which the depth information is stored together with a fixed spacer in the cement water mixture in a fresh state,
The step (c) includes a step of reading the intensity value of the radio signal and the depth information received by the reader or reader/writer,
The step (d) includes a step of detecting the separation distance between the reader or reader/writer and the cement water kneaded body, and also includes the step of detecting the separation distance between the reader or the reader/writer and the cement water kneaded body, and the information regarding the separation distance and the radio signal read out in the step (c). The estimation of the amount of water contained in the cement water kneaded body according to claim 6 , characterized in that the amount of water contained in the cement water kneaded body is estimated based on the strength value of and the depth information. Method.

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