JP4633416B2 - Concrete management method - Google Patents

Description

The present invention embeds an embedded RFID module having a temperature sensor in a concrete structure or a concrete cast for a concrete member, and based on data read from the embedded RFID module by a reader / writer or the like, any material age of mainly grasp the initial material concrete strength in age or concrete state, which relates to how to manage the concrete, suitably etc. particularly when situ determining the demolding time of pouring concrete Can be used.

  In general concrete work, after the formwork is assembled and the concrete is placed in the formwork and cured for a certain period of time, it is estimated that the concrete has reached a predetermined strength that can be removed. Demolding.

  However, it is difficult to accurately determine the strength of concrete placed on site, and if the strength is insufficient at the time of demolding, the finished concrete structure or the demolding failure of the concrete members will adversely affect the workability and quality. There is a risk that. For safety reasons, it is conceivable to delay the demolding, but doing so will reduce the rotation rate of the formwork, increase the cost by extending the construction period, and also deteriorate the integrity at the jointed part of the concrete. There is a risk of adversely affecting the quality of the joint.

  The need for strength estimation in concrete work includes the estimation of the demolding time of general concrete structures, the removal time of support works, the movement time of the formwork in the slip form method, the determination of the road opening time in concrete pavement, etc. There is a need.

Furthermore, there is a problem that if the concrete is frozen before it hardens, it will cause frost damage and the required strength will not be obtained. As a guideline to avoid frost damage, it is better to demold at a strength of 3.9 N / mm ² or more. It is said that.

Moreover, the prestress introduction time in the prestressed concrete is defined in a form of, for example, 35 N / mm ² or more, and in that case, strength estimation is required.

  In addition, for precast concrete products, temperature control is necessary to prevent damage due to handling of the product after demolding or to confirm that the required strength is obtained at the time of shipment. In order to suppress temperature cracking, for example, pipe cooling is performed, but it is necessary to grasp the concrete temperature also in the management of the pipe cooling temperature.

  Thus, for concrete, there is a high need for grasping temperature and estimating strength at the initial age from various viewpoints.

  Conventionally, as a method of estimating the strength of concrete, a specimen (test piece) having a predetermined size and shape is manufactured from a portion of the concrete to be placed and tested under standardized test conditions such as a compression test. Based on the accumulated temperature according to the blending conditions and casting conditions. A method for estimating the strength of concrete from the strength estimation formula and its coefficient is often used.

  However, in order to accurately estimate the concrete strength using the accumulated temperature, it is necessary to measure the internal temperature of the placed concrete every predetermined time. Or measuring the internal temperature by embedding a wired sensor in the concrete.

  The former method of making a hole in the concrete has an adverse effect on the strength and quality of the concrete even if the grout or the like is filled after the measurement, and it takes time and effort to drill the hole and measure the work. The latter method of embedding the sensor also has a problem that the installation of the sensor is troublesome because of the wiring, and the wiring becomes an obstacle even when placing concrete.

  On the other hand, in Patent Document 1, as a nondestructive evaluation method and apparatus for concrete, a temperature sensor with a microprocessor or a non-volatile memory is embedded in concrete, and temperature and time data measured over time by the temperature sensor are included. A method and apparatus for estimating the strength of concrete by drawing out and calculating the integrated temperature are described.

  In Patent Document 2, as an embedded multipurpose sensor device, an RFID tag that is capable of wireless communication with an external reading device and provided with several types of built-in sensors and exterior sensors is embedded in a building such as a tunnel. In addition, a device for measuring the internal state of a building in a non-destructive manner has been proposed.

  Patent Document 3 discloses a reader / writer function that performs wireless transmission and reception between a collective transmission device (corresponding to an RFID tag) including a functional sensor group that detects an analog state quantity of each unit and the collective transmission device. A civil engineering / construction structure state inspection system is described which includes a mobile body having a map, and a map database showing the relationship between the ID of each sensor and an embedded position. As a form of the moving body in that case, a case where the moving body is mounted on a vehicle such as an automobile or a train or a thing carried by an operator is shown.

  In Patent Document 4, an RFID tag is attached to a concrete specimen for compression test, and order information recorded on the RFID tag, information on a collection date, a test date, a strength test, and the like are browsed through a communication network, and concrete management is performed. An RFID system for concrete quality control that can be used is described.

In addition, Patent Document 5 describes an invention in which an electromagnetic induction IC chip is incorporated into a curb, and Patent Document 6 describes an invention related to an RFID tag and a reader / writer that can handle a plurality of different standards.
Japanese Patent Publication No. 07-050104 JP 2001-201373 A Japanese Patent No. 3416875 JP 2004-109002 A Japanese Patent Laid-Open No. 11-081214 JP 2004-213582 A JP-A-11-126293

  As shown in Patent Documents 1 to 4, an embedded sensor or an RFID tag with a sensor is embedded in concrete to measure the state of the concrete, and information is obtained by a reader / writer or wireless communication. Various attempts have been made, and Patent Document 1 describes that temperature measurement is performed to obtain an integrated temperature.

  However, the device described in Patent Document 1 requires wiring between the sensor and the microprocessor, and it is difficult to embed the sensor, the microprocessor, the nonvolatile memory, or the like (sensor module) at a predetermined position in the concrete. . In addition, the temperature at every predetermined time is simply measured and stored in a memory so that it can be taken out together, so that the site worker can easily grasp the concrete state immediately at the site. Not. In addition, the estimation of concrete strength from the accumulated temperature is performed by calculating the data extracted from the memory with a computer, but the effective use of the sensor module after obtaining the estimated strength from the accumulated temperature is particularly considered. In other words, the embedded sensor module for which the purpose of use has been completed is left as it is.

  Patent Documents 2 and 3 attempt to grasp the state of concrete wirelessly by combining several types of sensors and RFID tags, and the invention described in Patent Document 3 further embeds sensors. Although a configuration for storing a sensor ID for giving a position is described, the physical property data is premised on the use of an external information management device such as an external database, and it is insufficient in terms of concrete management on site.

  The invention described in Patent Document 4 is such that information on a specimen used for a compressive strength test can be managed through a communication network, but does not have a function of managing the state of concrete in an actual structure. The technology cannot be applied to actual structures as they are.

The present invention is intended to solve the above-described problems in the prior art, and by using an embedded RFID module equipped with a sensor, all wireless communication is performed without wiring to the sensor. Efficiently grasp and manage the concrete condition such as the temperature and strength of the initial age, and easily extract not only the strength but also the concrete condition and history and additional information on the concrete used in the future. is an object of the present invention to provide a method of managing also possible concrete can be effectively utilized.

In the concrete management method according to claim 1 of the present application, a plurality of embedded RFID modules equipped with temperature sensors are embedded in the cast concrete, temperature is measured every predetermined time, and the integrated temperature calculated from the temperature data is measured. A method of grasping and managing the state of the placed concrete using a degree , wherein the concrete is used as the placed concrete (concrete in which the embedded RFID module is embedded) in the plurality of embedded RFID modules. It may be stored position information about the embedded position of the concrete ID and the implantable RFID module, the concrete ID and the position information read from the plurality of embedded RFID module, concrete and the embedded using identify embedded position of the RFID module, it identified the concrete Using the corresponding based on the accumulated temperature strength estimation formula, and is characterized in that for estimating the intensity at arbitrary initial ages at the embedded position of each embedded RFID module of the punching setting concrete.

  In addition, the initial age in this invention is a period required in order to reach | attain the target intensity | strength in the intensity | strength range lower than the mixing intensity | strength of concrete.

  Although it is known that the strength of concrete increases over a long period of 100 years, the strength development of concrete depends on environmental conditions such as temperature and humidity. Usually, there are many examples in which the strength at the age of 28 days after curing concrete in water is the standard, but the initial age is the period required to reach a strength in a range lower than the standard strength. This is a period of about 2 weeks from the start of setting of concrete, or a period necessary to reach a strength in the range of about 80% of the final strength of concrete.

  The concrete identification by the concrete ID is indispensable in order to perform the strength estimation using an appropriate strength estimation formula. At the very least, what kind of concrete was used in concrete work should be specified.

  That is, for example, in a concrete manufacturing process, a concrete ID for identifying a set of concrete is assigned to each piece of concrete to be handled, for example, a serial number, an alphabet, or an ID based on a combination thereof. Is granted.

  As a unit of concrete to be handled in a lump (a range in which the same concrete ID is given), a unit of concrete shipped from the same batch in the manufacturing process is considered suitable, but is not limited to this. For example, It is also conceivable to assign an ID to each piece of concrete loaded for each vehicle such as an agitator truck used for shipping concrete.

  At what point in the manufacturing process, shipping process, etc., the concrete ID is assigned, and the range of concrete that is assigned the same concrete ID affects the accuracy of how much concrete can be specified. However, it can be arbitrarily determined in relation to workability, accuracy, data processing amount, and the like.

  Also, the concrete ID does not necessarily have to be one. For example, a concrete ID for each batch and a concrete ID for each vehicle for shipment are given in two stages, or three or more if necessary. It is also possible to grant.

  If concrete ID is given, if necessary, various types of use conditions during construction that affect concrete, concrete mix, concrete, strength and performance of concrete specified using concrete ID (for example, It is also possible to grasp additional information on the concrete used, such as the transport time of raw concrete, weather conditions, and temperature.

  From the identification of concrete by these concrete IDs and grasping of additional information on the specified concrete, a strength estimation formula and its coefficient that give the relationship between the integrated temperature and strength are specified, or they are corrected as necessary.

When storing concrete I D is the embedded RFID module, identifies the concrete using the concrete ID as pouring concrete based, computer, etc. The concrete stored in the database of the (which may be a paper document) Information necessary for strength estimation and the like can be extracted.

  Information on the used concrete is stored in the computer brought to the site along with the concrete ID, and the database in the control room outside the site (database managed by the subcontractor's concrete manufacturer, etc.) In some cases, the information is stored together with the concrete ID. In the latter case, based on the concrete ID, it is also possible to check the information related to the concrete by using a communication network such as the Internet even from the site and extract the information.

  The RFID that is a constituent element of the embedded RFID module having a sensor for measuring the state quantity of a measurement target such as a temperature sensor used for concrete management of the present invention is not particularly limited, but is usually between a reader / writer. With an antenna for transmitting and receiving data, a memory such as a nonvolatile RAM as a storage unit for storing data, an IC chip (microprocessor) as a control unit, etc. A power source that is dielectrically generated by electromagnetic waves transmitted from the reader / writer can be used.

However, in order to make the sensor function, it is usually necessary to incorporate a battery, and a power source using a battery can be used as a part of a power source for control. In that case, for example, in order to use it for a long period of time in addition to temperature measurement related to the accumulated temperature while being embedded in concrete, it is necessary to suppress battery consumption when not in use as much as possible. It is conceivable that the switch is switched by a signal from the writer and power is supplied from the built-in battery only for a period during which the temperature sensor functions.

  The temperature sensor applicable to the present invention includes a resistance temperature detector (using the increase in electrical resistance of pure metal with temperature), thermistor (oxide powder mainly composed of manganese, nickel, cobalt, etc.). Ceramics whose resistance changes with temperature), thermocouples (using the creation of a closed circuit with two types of conductors called the Seebeck effect, and generating an electromotive force due to the temperature difference between the contacts) In addition, an IC temperature sensor using the temperature characteristics of the transistor can be used.

  When it is desired to grasp the state quantity of concrete other than the temperature, the integrated temperature, and the estimated strength based on the temperature, for example, a combined use of a humidity sensor and a strain sensor can be considered.

  Since the humidity of the concrete affects the strength development of the concrete, it is possible to improve the accuracy of strength estimation by measuring the humidity together with the temperature using a humidity sensor.

  As the type of humidity sensor, for example, lithium chloride, a polymer material or ceramics is used as a moisture sensitive material, and an electrical resistance humidity sensor in which the electrical resistance between the electrodes changes in response to humidity change, and the polymer material between the electrodes An electric capacity type humidity sensor that changes the electric capacity with respect to the humidity change can be used.

  The strength of concrete is manifested by the progress of cement hydration. The hydration reaction is a chemical reaction and involves shrinkage as the hydration progresses. The strength can be estimated by measuring the strain amount of the concrete with a strain sensor, and the occurrence of temperature cracks caused by the exothermic reaction that occurs as the hydration progresses can also be estimated.

  Examples of the strain sensor type include a strain sensor that utilizes a change in electrical resistance as it expands and contracts, and an optical fiber strain sensor that utilizes an interference effect of light.

In the management method of the concrete according to claim 1, the embedded RFID module, Contact Ku by storing positional information relating to the embedded position of the write-type RFID module embedded in further.

  The position information in this case is, for example, information on which position of which member in the concrete structure, depth from the concrete surface in the concrete member, position information obtained by surveying, etc. It is conceivable to use a combination of position information.

  The RFID module cannot be visually confirmed after being embedded in concrete, but by storing such position information directly in the embedded RFID module, based on the position information, The position of the module can be immediately identified without collating it with data stored in an external database or design drawings.

  In addition, the data read from the embedded RFID module is corrected as necessary in relation to such position information, or the temperature distribution in the concrete and other various information in relation to other embedded RFID modules. Can be grasped.

Claim 2 is the method for managing concrete according to claim 1, further is characterized in that to keep additional information also is stored relating to the Concrete to or used used.

  The additional information here is not limited to the information necessary for estimating the strength of the concrete, such as the composition of the concrete, but information related to the shipment of concrete such as the construction name, the name of the orderer, and the name of the contractor, or simply for reference. It may be information to be used (see Table 1 described later), and any information that the user considers necessary can be selected.

  If additional information about concrete is stored in the embedded RFID module, the stored necessary information can be directly accessed from the embedded RFID module without accessing a separate external database and performing verification. Since the data can be read out, the operator can obtain necessary information immediately at the site without requiring troublesome work such as connection to an external database.

  In addition, even after the date has passed and management by strength estimation is no longer performed, information about the concrete used is directly extracted from the embedded RFID module at an arbitrary time (for example, when deterioration becomes a problem) The construction status of concrete can be grasped.

Claim 3, Oite the management method of the concrete according to claim 1 or 2, wherein the implantable RFID module includes an antenna unit for transmitting and receiving data by wireless communication with the reader / writer, the antenna section An RFID controller that is driven by power obtained by wireless communication from the reader / writer and that transmits information stored in the shared storage unit to the reader / writer in accordance with an instruction from the reader / writer; A temperature sensor for measuring the temperature of the cast concrete; a sensor control unit for operating the temperature sensor to obtain information on the state quantity; a power supply for sensors for driving the temperature sensor and the sensor control unit; It is connected to the RFID control unit and the sensor control unit, and is based on an instruction from the RFID control unit or the sensor control unit. It is characterized in that it has a shared storage unit for reading and writing data is performed.

  The basic configuration is that a sensor is built in a known RFID tag and a battery is built in as a power source. By combining it with a reader / writer, information can be easily transmitted and received by wireless communication. And inexpensively.

  With regard to specific forms and configurations, when embedded in concrete, it will not adversely affect the concrete as a foreign object. In combination with a sensor that consumes a large amount of power, it can be used for a long period of time with minimal battery consumption. A configuration is desirable.

  Measurement objects include various construction materials such as mortar and exterior members in addition to concrete. Examples of the sensor for measuring the state quantity include various sensors such as an ion sensor and a pH sensor in addition to the temperature sensor, the humidity sensor, and the strain sensor.

The invention Te management odor concrete, for using an embedded RFID module with sensors, with is easy removal of the state quantity measurement and data such as temperature inside the concrete, in the embedded RFID module, the use of concrete Since the concrete ID is stored and the concrete can be specified by the concrete ID, the optimum strength estimation formula and its coefficient can be selected and corrected for each concrete actually used. In addition, it is possible for a site worker or the like to easily and efficiently estimate the strength of concrete using the accumulated temperature even from the site.

  For example, using a reader / writer, it is possible to immediately grasp the concrete state such as temperature, accumulated temperature, estimated strength, etc. at the site, so the construction can be streamlined and the construction period can be shortened in relation to the work process of the entire concrete work. I can plan.

Moreover, embedded positional information embedded position of the write-type RFID module by leaving was directly stored and conventionally the data stored in an external database like, or even without checking the design drawing or the like, on the basis of the position information There is an advantage that the position of the module can be confirmed immediately on site, and it can be used for grasping temperature distribution and other information in concrete.

In the invention according to claim 2 , not only the initial age but also the strength can be stored in the embedded RFID module by storing additional information regarding the concrete used together with the concrete ID for specifying the concrete. Even after management by estimation is no longer performed, various information about the concrete can be directly extracted from the embedded RFID module at any point in time, and the concrete construction status and the like can be grasped.

  FIG. 1 conceptually shows an embodiment of the concrete management method of the present invention, where the upper right part is a site worker such as a construction worker, the area of the site manager, the lower left part is a concrete producer, etc. It is an area for concrete contractors. In this example, it is assumed that the on-site contractor uses the external database 11 of the concrete producer through the communication network 12 such as the Internet. However, the present invention is not limited to such a case, and will be described later. It is also possible to complete concrete management on site.

  Hereinafter, this embodiment will be described in correspondence with the flowchart of FIG.

(1) Until shipment of concrete (producer side)
The concrete producer manufactures concrete according to the design standard strength and instructions required by the orderer or contractor, and concrete (for example, concrete manufactured in the same batch) that is handled as a whole in the manufacturing process or the unloading process. In addition, an ID for specifying the concrete, etc. loaded on the same vehicle when separated for loading on an agitator truck, etc. is given at the time of manufacture or shipment, and is compounded in a database managed by the producer, etc. Register the concrete ID along with matters that affect the strength of the concrete (such as manufacturing records).

  Further, if necessary, the strength estimation formula used when the strength is estimated based on the integrated temperature, its coefficient, and the correction formula, correction coefficient, etc. as necessary are also registered with each concrete ID. In this case, the intensity estimation formula or the like is generally extracted from a large amount of past data, and may be based on the producer's own data or may be created by a third party. The correction formulas and correction factors given at the time of shipment are based on past data and the like in advance for various factors affecting the strength of concrete, such as temperature and other weather conditions, transport time of concrete, etc. There is something prepared for.

  In this way, the produced concrete is loaded into an agitator truck or the like in the state of raw concrete and shipped to the site. In that case, you may register and issue the above-mentioned concrete ID for every batch and vehicle in production of ready-mixed concrete. The concrete applied to the present invention is not particularly limited.

(2) From receiving concrete on site, installing embedded RFID modules to estimating the strength of cast concrete (when no specimen is used) (constructor side)
The concrete carried by the agitator truck 1 or the like is placed in a formwork assembled at the site by pumping or the like, and a part of the concrete is used for preparing a specimen 4 for a strength test or the like.

  At that time, the embedded RFID module 2 having a temperature sensor is installed in each part of the concrete structure 3 to be constructed. This embedded RFID module 2 is set in advance in a formwork by using reinforcing bars or the like arranged in the concrete structure 3, and the concrete is placed in that state, or the placed concrete Can be installed by embedding in concrete directly afterwards.

  Although a specific example (FIG. 3) will be described later, the embedded RFID module 2 includes an antenna that transmits and receives data to and from the reader / writer 5, as described in the section for solving the problem, A sensor such as a temperature sensor or a battery is built in an RFID tag equipped with a memory such as a nonvolatile RAM for storing data, an IC chip as a control unit, etc. By the timer function, the temperature inside the concrete (position where each embedded RFID module 2 is embedded) can be measured by a temperature sensor every predetermined time, and the time and temperature can be stored in the memory.

  By reading these data relating to the temperature inside the concrete and the concrete ID with the reader / writer 5 for each embedded RFID module 2, the integrated temperature at that time is calculated, and the strength of the concrete is calculated based on the integrated temperature. Can be estimated.

  In other words, the strength estimation of concrete based on the accumulated temperature is such that the relationship between the accumulated temperature and the strength can be obtained if the cement type, fineness, blending, etc. are the same under certain conditions. Is applied to the optimum strength estimation formula (including the coefficient) that gives the relationship between the accumulated temperature and strength stored in the database owned by the producer for the concrete specified by the concrete ID. The strength of concrete can be estimated. Thereby, the estimated intensity can be obtained simply and efficiently even at the site.

  In the example shown in FIGS. 1 and 2, the concrete ID is transmitted from the reader / writer 5 to the producer's database 11 via the network 12 at the site, and the optimum strength estimation formula for the concrete corresponding to the concrete ID is transmitted. The calculated temperature is calculated by substituting the integrated temperature calculated in the reader / writer 5 into the intensity estimation formula, and displaying the calculation result.

  Note that this is a case where the reader / writer 5 has a terminal function, a calculation function, a display function, and the like. If the reader / writer 5 does not have a terminal function or a calculation function, the personal computer brought to the site. Or the like.

  Table 1 shows a simplified example of data items stored in the external database 11 of the concrete producer and data items to be written in the storage unit of the embedded RFID module 2 (for illustrative purposes only) Actually, it depends on purpose and management method).

  In Table 1, ◎ (double circle) is an indispensable item, ○ (circle) is a highly convenient item, ★ (black star) is a further indispensable item for correction in accelerated curing, and external database 11 side (Table DB column) and embedded RFID module 2 side (table MD column) are displayed separately.

  Instead of browsing the database 11 owned by the producer, the data of the strength estimation formula based on the concrete delivered to the on-site computer or the data corresponding to the database 11 is read in advance or recorded on the recording medium. It is also possible to calculate the strength estimation using the data, and in that case, the management of the concrete of the present invention can be completed within the construction site.

  There are data items (MD column) on the embedded RFID module 2 side that are written before the measurement of the integrated temperature, and data items that are written after the measurement of the integrated temperature and the intensity estimation. The concrete ID and the like should be written before measuring the accumulated temperature, and other items relating to the name of the concrete, the concrete composition, the material, and the RFID module are usually written before measuring the accumulated temperature. Of course, the items related to the actual measurement values are written after the measurement. These writings are performed by the reader / writer 5.

  The data stored in the embedded RFID module 2 is contactless by holding the reader / writer 5 close to the embedded RFID module 2 even after demolding or after the construction of the concrete structure is completed. This information can be read out with. Further, the reader / writer 5 can restart a temperature sensor or the like as necessary, and the measurement information at that time can be used for managing concrete.

Embedded RFID module 2, the concrete structure 3, but are embedded multiple, portions concrete ID is different, a must have at least 1, further regard to parts or the same measuring point of the same concrete ID, a plurality dispersion By arranging them at multiple intervals in the depth direction, the temperature distribution (temperature map) inside the concrete can be obtained, and the temperature measurement data at each measurement point and the uneven temperature distribution It is possible to estimate the concrete strength more accurately by performing correction. Furthermore, an intensity distribution (intensity map) can also be obtained.

  When grasping which part of the concrete structure 3 the strength estimated by the above method is used, and when creating a temperature distribution map, it is important to confirm the embedded position of the embedded RFID module 2 in the concrete. The position information can be stored in the external database 11 or a computer at the site. However, if the position information is stored in the storage unit of the embedded RFID module 2 together with the concrete ID, each embedded RFID module can be stored. The position of 2 can be immediately identified.

(3) Correction of strength estimation formula using specimen (producer or contractor)
In the above example, the strength is estimated without performing the test with the specimen, but it is preferable to correct the strength estimation formula from the test result with the specimen. In particular, when the concrete strength is estimated using a specimen made of the same concrete as the concrete used for placing, the strength can be estimated accurately.

  In the conceptual diagram of FIG. 1, about the specimen 4 created using the same concrete as the concrete cast on the construction site, in addition to the normal strength test such as the compression test, the specimen 4 was also used for the actual structure. A manufacturer or the like who embeds the embedded RFID module 2a and controls the specimen 4 reads the time and the temperature inside the specimen 4 with the reader / writer 5a, and inputs this to the database 11 together with the integrated temperature. It has a configuration.

  For example, when estimating the concrete strength in order to demold the concrete structure 3 that is an actual structure, the strength expression of the specimen 4 is expressed from the concrete structure 3 by accelerated curing with an increased curing temperature. It is desirable to know in advance the relationship between the strength development property and the integrated temperature in concrete actually used, and it is conceivable to shorten the curing time by raising the curing temperature from the actual structure. However, the temperature range in that case is a range that does not significantly affect the relationship between the integrated temperature and the strength.

  For the specimen 4, a normal compressive strength test or the like is performed in addition to the above temperature measurement, the relationship between this and the integrated temperature based on the data read from the reader / writer 5a is obtained, and a known general registered in the database in advance If the intensity estimation formula needs to be corrected, the coefficient in the intensity estimation formula is corrected and the strength estimation formula is updated.

  However, there are various different conditions, such as differences in shape and dimensions, differences in the embedding depth of the embedded RFID modules 2a and 2b, differences in curing conditions, etc. In consideration of the above, when it is determined that correction is necessary, correction of the intensity estimation formula or the like is performed.

  In FIG. 1, the embedded RFID module 2 a is embedded in the specimen 4 for strength test, and both the temperature measurement (measurement for calculating the integrated temperature) and the strength test are performed with one specimen 4. However, depending on the form and size of the embedded RFID module 2a and the manner in which it is embedded, the strength test results may be affected. Therefore, it is possible to create a temperature measurement specimen and a strength test specimen separately. It is done.

  FIG. 3 shows a module system diagram of an embodiment of the embedded RFID module 2 used in the present invention.

  The basic configuration is the same as that of a general RFID tag including an antenna, a power rectifier circuit, a nonvolatile RAM as a storage unit, and an IC chip. In this example, the temperature sensor 10 and the battery 9 are built in. .

  The overall shape may be a card shape that is common in general RFID tags, but since it is embedded in concrete, it is preferable that the overall size be about the maximum diameter of the aggregate or less. Also, the shape is preferably a shape that does not cause cracks as a foreign matter in the concrete as much as possible, and it is conceivable to embed it integrally with a three-dimensional artificial bone or the like.

  Furthermore, in the case of mounting and fixing and embedding in a reinforcing bar arranged in a concrete structure, it is preferable to provide a fixing bracket or a binding wire on the surface of the RFID module.

  The configuration and function of the embedded RFID module 2 will be described below with reference to the module system diagram of FIG.

(1) When accessing from the reader / writer 5, the power rectifier circuit 22, the receiving circuit 23, the data processing logic circuit 24, the transmission modulation 25, the clock extraction 26, and the nonvolatile RAM operate with the energy supplied from the reader / writer 5. Therefore, the internal battery 29 is not consumed during this time.

(2) When activated by a command from the reader / writer 5, the temperature data measured by the temperature sensor 30 is taken into the CPU 27 via the A / D converter at a time interval set in advance by a timer in the CPU. And stored in the non-volatile RAM 28.

(3) The CPU 27 is configured so that the built-in battery 29 is turned on for the time required for the measurement at every measurement interval by the built-in timer, thereby reducing power consumption.

(4) When a data collection command is given from the reader / writer 5 to the data processing logic circuit 24, the data in the nonvolatile RAM 28 is read and sent to the reader / writer 5 by the transmission modulation 25, and thus the reader / writer 5 is read out. Data collection by the writer 5 is performed.

(5) After all the data stored in the nonvolatile RAM 28 is sent to the reader / writer 5, once the temperature data in the nonvolatile RAM 28 is cleared and new temperature data is stored, the nonvolatile RAM 28 Over memory can be prevented.

(6) The measurement time interval can be changed by a command from the reader / writer 5 as necessary.

  The configuration of the embedded RFID module 2 described above is merely an example of an RFID module that can be used in the present invention, and various modifications can be made to the specific configuration.

  Next, the case where the strength of the construction model is estimated from the relationship with the accumulated temperature using the specimen will be described more specifically.

(A) In the construction of a beam of a reinforced concrete frame structure, the concrete management method according to the present invention should be taken into consideration when it is necessary to remove the support work in advance because of safety issues and 12 N / mm ^{2 is} required. The strength after driving is estimated using, and the removal timing of the demolding and support work will be managed.

(B) The concrete used is ordinary concrete with a nominal strength of 18 N / mm ² , slump of 18 cm, and a maximum size of coarse aggregate of 25 mm using ordinary cement made of ready-mixed concrete. Usually, the display format 18-18-25N is used).

  The producer uses a concrete conforming to the above-mentioned standard (hereinafter referred to as standard concrete) kneaded in advance on a different day from the placement date, and molded into a cylindrical specimen having a diameter of 10 cm and a height of 20 cm. The specimen is prepared, the specimen strength and specimen temperature are continuously measured at room temperature in advance to obtain the accumulated temperature, and each coefficient of the accumulated temperature formula for this standard concrete is set. The specimen temperature is measured by installing the embedded RFID module of the present invention at the center of the specimen using a thin resin rod and embedding it in concrete.

  The integrated temperature formula is given as a general formula as follows.

here,
t (n): nth temperature from the start of measurement (° C.)
I (n): Time from concrete production (placement) at the nth (i time)
k: n at the end of measurement
c: Constant (in this test example, −5 ° C. is used)
Moreover, the intensity | strength estimation formula decided to use the following formula | equation.

here,
F _C : Estimated strength F ₂₈ : Compound strength (in this example, 21.6 N / mm ² increased by 20% with respect to nominal strength 18)
a, b: Constants determined by concrete

Fig. 4 shows the test values (solid squares) of test specimens of standard concrete corresponding to the concrete standards of the concrete to be placed (specimens of concrete mixed on a different day from the placement date) and the test The strength estimation formula A based on constants a and b (a _f and b _f , 15.5 and 0.704, respectively) determined using the least square method from the values, and this was determined in consideration of variation in the composition constants a and b in the confidence limits (a _r, and b _r, respectively 22.0 and 0.70) shows by the intensity estimating equation (intensity estimating equation by confidence limits) B as a model example.

At the same time as the production of ordinary 18-18-25N concrete required for placement, the producer uses the concrete ID corresponding to the agitator truck for transporting concrete, the strength estimation formula used (formula (2)), and the above-mentioned specimen. Access F ₂₈ , a _f , b _f , a _r , b _r , or the above strength estimation formula A and strength estimation formula B, which are usually required for estimating the concrete strength of 18-18-25N based on the test results, from the Internet. Register in a possible database.

(C) The concrete structure to be constructed is a beam of a reinforced concrete ramen structure building structure with a concrete design standard strength of 18 N / mm ² (simulated specimen), height 600 mm, width 400 mm, length 2 .8m.

  The embedded RFID module equipped with the temperature sensor of the present invention is arranged in the longitudinal direction within the cross section of the specimen shown in FIG. 5, for example, by using the reinforcing bar arranged in the mold and the resin rod. A total of 24 are installed in 4 different locations. The RFID module has a communication frequency of 13.56 MHz with a module ID, is equipped with a thermistor as a temperature sensor, a CPU, and a battery, and is compatible with anti-collision molded with a resin with an outer diameter of 25 mm and a thickness of 9 mm. .

  Immediately after installing the RFID module, information on the buried position and additional information on the concrete used such as concrete manufacturer, installer, construction date, design standard strength, concrete standard, etc. are stored in the RFID module storage unit using a reader / writer. Write to.

  After receiving concrete ID from the producer at the time of receiving concrete, placing concrete directly on the formwork, using a reader / writer, writing the concrete ID corresponding to the placed concrete into the RFID module and at the same time every hour Set the measurement time interval to measure the temperature. In addition, an instruction to start measurement is given to the RFID module using a reader / writer (thereby, the internal switch is turned on to switch to a temperature measurement control state using a battery).

(D) Instead of the strength estimation formula (B in Fig. 4) based on the reliability limit in (B) above, use the same concrete as the concrete used for placing, at a constant temperature higher than the daily average temperature at the site. Preparation of the specimen when using the strength estimation formula (C in FIG. 4) by the specimen subjected to the accelerated curing is performed as follows.

  At the same time, concrete is placed on the formwork of the actual structure on the site, and at the same time, a cylindrical specimen having a diameter of 10 cm and a height of 20 cm is prepared for the strength test. Separately, for measurement of the specimen temperature history, the RFID module is embedded in a specimen having the same shape as the specimen for strength test, and the measurement is started simultaneously with writing the concrete ID with a reader / writer.

The producer takes the specimen home and estimates that it is higher than the daily average temperature at the site. For example, when the daily average temperature is 15 ° C, the producer performs accelerated curing at 35 ° C. The producer conducts a compressive strength test using specimens accelerated and cured every 24 hours. After the end of the test after 72 hours, a strength estimation formula is determined using the least squares method from the test results (after 72 hours have passed). The coefficients a _c and b _c of 14.0 and 0.709) are appropriately registered in the database corresponding to the concrete ID.

  Table 2 summarizes the integrated temperature and compressive strength test results of the specimens that were subjected to accelerated curing using the same concrete used for on-site placement. As will be described later with reference to Table 3, when accelerated curing is performed on a specimen made of the same concrete as the concrete used for placing, when the reliability limit is considered for a specimen made of the same standard but different concrete In comparison, it is possible to estimate the intensity with higher accuracy. That is, in terms of accuracy, it is important to obtain a strength estimation formula using a specimen made of the same concrete as the concrete used for placing.

  FIG. 4 shows a model example of the strength estimation formula C based on the measured value (white circle) of the test specimen by the accelerated curing, together with the strength estimation formula A and the reliability estimation formula B based on the reliability limit for the standard concrete described above. Is shown.

  In this case, since the cast concrete and the concrete of the specimen are the same, it is not necessary to consider the variation in the concrete composition due to different mixing dates (concrete production dates).

(E) After a certain period of time has elapsed since the concrete placement, the reader / writer is used to read the concrete ID, measured data, and buried position information of each RFID module.

After that, when the reader / writer is connected to the Internet and the concrete ID is searched as an index and the strength is estimated based on the confidence limit, the strength estimation formula and the coefficients F ₂₈ , a _r and b _r are promoted. When strength is estimated by curing, the strength estimation formula and the coefficients F ₂₈ , _ac and b _c are taken into the reader / writer, and at the same time the integrated temperature of the concrete placed using formula (1) is calculated. Calculation is performed for each RFID module, and the concrete strength is estimated using Equation (2), and the strength estimation result and embedded position information for each RFID module are displayed on the reader / writer screen. Thereby, for example, as shown in Table 3, an estimated strength value of the cast concrete at each initial age can be obtained.

  Table 3 shows the strength estimates obtained by considering the reliability limit from the test results of the specimens made of concrete different from the concrete actually used for placing, although the standards are the same. This is a comparison of strength estimates obtained from the test results of specimens made from the same concrete used for placing and accelerated and cured. Differences in estimated intensity due to differences in embedding positions are shown by ranges.

  Although the temperature history that affects the strength development of concrete varies depending on the embedded position of the RFID module with a built-in sensor, the strength at each position of the concrete can be easily grasped according to the present invention, and the concrete position after each elapsed time can be determined. It is also possible to grasp the difference in strength due to the difference and the overall image of strength expression at each age.

In this example, it is possible to secure 12.0 N / mm ² capable of removing the support work after about 144 hours when the strength estimation value considering the reliability limit corresponding to the concrete standard is used. When using the strength estimation formula by accelerated curing with the same concrete as the concrete actually used that enables high-precision estimation, it is easy for field workers to directly and easily at each construction site after 72 hours. Can be guessed.

  The method using the estimated strength value based on the reliability limit is not necessary to perform accelerated curing separately, and it is easy and efficient to perform a search using the concrete ID as a clue by effectively utilizing the database accumulated in the past. This method is feasible. However, in terms of the accuracy of the estimated strength, it is necessary to consider the influence of the difference in the lot of material used and mixing due to different mixing dates as a safety factor even if the concrete corresponds to the same concrete standard, and it is not always sufficient. There are cases where it cannot be said.

  The method using the strength estimated value by accelerated curing of the specimen with the same concrete used for placing is more accurate than using the strength estimated value due to the reliability limit, and usually the support work can be removed in a short time. It becomes. However, facilities and heat sources for accelerated curing are required, and when performing a large amount, it is affected by labor and cost.

  Furthermore, in the estimation of strength by accelerated curing of the specimen with the same concrete, the accuracy improves as the specimen age, so the correction value obtained from the result of the strength test can be immediately known on site. Can do. In addition, by using a database with a concrete ID as a clue, an estimation formula obtained from a strength test result carried out by a producer can be immediately searched on site.

As described above, in the embodiment of the present invention, including a specific construction model example,
(a) Access the database using the concrete ID as a clue and estimate the strength without using the specimen.
(b) Information on strength estimation formulas, safety factors and correction factors obtained using concrete specimens of the same concrete standard as the concrete used for placing in advance is registered in the database, and the concrete ID is used as a clue to the database. To access and estimate strength (strength estimation based on confidence limits).
(c) Information on strength estimation formulas and correction factors obtained by accelerated curing of specimens made from the same concrete used for placing during concrete placement is registered in the database, and the concrete ID is used as a clue. Access the database to estimate strength (strength estimation by accelerated curing).
However, since there are advantages and disadvantages in terms of efficiency and accuracy, the method for estimating the strength may be selected as appropriate. If accuracy is important (c), efficiency is important (a), and average is (b).

  On the other hand, even after completion of the purpose of estimating the strength in the present invention, for example, when repairing or dismantling concrete after several decades from the placement of concrete, information on the burial position using the reader / writer, the contractor, and the construction date It is possible to read out additional information regarding the concrete used, such as design standard strength and concrete standards. The merit is, for example, that it is not necessary to search for materials such as construction records and design books after several decades.

  Further, even when the on-board battery is already consumed, as shown in FIG. 3 which is a configuration diagram, access to the nonvolatile RAM or the like in which the information is written does not require a battery and is supplied from the reader / writer. The written information can be read without problems.

It is a conceptual diagram which shows one Embodiment of the management method of the concrete of this invention. It is a flowchart corresponding to the conceptual diagram of FIG. It is a module system diagram showing one embodiment of an embedded RFID module used in the present invention. It is a graph which shows the relationship between the integrated temperature and the intensity | strength of the use concrete in the example of more concrete embodiment. It is sectional drawing which shows the example of arrangement | positioning in the beam concrete of an embedded type RFID module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Agitator track, 2, 2a ... Embedded RFID module, 3 ... Concrete structure, 3a ... Concrete, 3b ... Reinforcing bar, 4 ... Specimen, 5, 5a ... Reader / writer, 11 ... Database, 12 ... Network, DESCRIPTION OF SYMBOLS 21 ... Antenna, 22 ... Power supply rectifier circuit, 23 ... Receiver circuit, 24 ... Data processing logic circuit, 25 ... Transmission modulation, 26 ... Clock extraction, 27 ... CPU, 28 ... Nonvolatile RAM, 29 ... Built-in battery, 30 ... Built-in Temperature sensor

Claims (3)

Provides temperature measurement every predetermined time embed a plurality of implantable RFID module with a temperature sensor in pouring concrete, using the integrated temperature calculated from the temperature data, know the state of the ball striking setting concrete and a method for managing, in the plurality of embedded RFID module, may be stored position information about the embedded position of the concrete ID and the implantable RFID module of the concrete to be used as a pouring concrete, said plurality of the concrete ID and location information read from the implantable RFID module, identifies the embedded position of the concrete and the embedded RFID module using the intensity estimating equation based on accumulated temperature corresponding to the identified said concrete with, embedded in the embedded RFID module of the punching setting concrete Management method of concrete and estimates the intensity at arbitrary initial ages in location. Wherein the embedded RFID module, further management of the concrete according to claim 1 Symbol mounting, characterized in that keep additional information also is stored about Concrete to or used used. Oite the management method according to claim 1 or 2, wherein the concrete, the embedded RFID module, an antenna unit for transmitting and receiving data by wireless communication with the reader / writer, is connected to the antenna unit, the It is driven by power obtained by wireless communication from the reader / writer, and an RFID control unit for transmitting the information stored in the shared storage unit in accordance with an instruction from the reader / writer to the reader / writer, the pouring concrete a temperature sensor for measuring the temperature, and the state quantity obtaining information about the sensor control unit operates the said temperature sensor, and the sensor power for driving the temperature sensor and the sensor control unit, the RFID control unit and Connected to the sensor control unit and read / write data based on instructions from the RFID control unit or the sensor control unit Management method of concrete and having a shared storage unit is performed.

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