Method for estimating strength development of hydraulic composition, and program for estimating strength development of hydraulic composition

Abstract

To provide a method for accurately estimating a strength development of a hydraulic composition by an easy method.SOLUTION: The method for estimating the strength development of a hydraulic composition according to the present invention includes the steps of: collecting a part of a hydraulic composition to be placed in a placing region or of a hydraulic composition placed in a placing region as a sample (step a); heating the sample under a predetermined heating condition after the hydraulic composition is placed in the placing region (step b); measuring the change of mass of the sample before and after step b (step c); and determining whether the hydraulic composition placed in the placing region has reached a strength development time on the basis of the result of measurement in step c.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for estimating the strength development of a hydraulic composition, and also to a program executed for estimating the strength development of a hydraulic composition. [Background technology]

[0002] Predicting the strength development in concrete and mortar during construction is important from the viewpoint of ensuring the durability and quality of concrete structures.

[0003] For example, during the construction stage of floor concrete, fresh concrete is poured, and finishing work is carried out after hydration progresses and a certain level of strength is achieved. Also, during the construction stage of concrete structures, the formwork is removed (demolition) once a certain level of strength is achieved. Furthermore, when prestressing steel strands are introduced into concrete to create prestressed concrete, prestressing is also carried out once a predetermined level of strength is achieved. Specifically, in the case of the post-tensioning method, tension is applied to the prestressing steel strands once a predetermined level of strength is achieved. Conversely, in the case of the pretensioning method, tension is applied to the prestressing steel strands once a predetermined level of strength is achieved after they have been introduced.

[0004] However, in the past, determining whether fresh concrete had hardened and reached a predetermined strength, i.e., for example, when it was time to finish the surface, was largely dependent on the contractor's intuition, and there was a problem that the timing of the judgment varied depending on the contractor's level of proficiency.

[0005] Patent Document 1 discloses a technique in which resistance detection sensors are embedded at multiple locations within a concrete skeleton, and when the sensors reach a predetermined resistance value, it is detected that the time for leveling has arrived. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-340938 Summary of the Invention [Problem to be solved by the invention]

[0007] The penetration resistance test specified in JIS A 1147 is known as a method for determining the hardening state of concrete. This method detects the degree of hardening by the penetration resistance value when a specified penetration needle is inserted vertically into the mortar specimen. By measuring the penetration resistance value at multiple points over time, it is possible to determine the hardening state of concrete at the initial stage (when the penetration resistance value reaches, for example, 3.5 N / mm 2 The time until the penetration resistance reaches, for example, 28.0 N / mm 2 From the approximate curve of these plots, the relationship between the penetration resistance value and elapsed time can be obtained.

[0008] However, to detect the hardening state of concrete using this method, it is necessary to prepare a test specimen every time a time passes, insert a penetration needle vertically, and measure the penetration resistance value, which can be cumbersome.In addition, since a dedicated testing device is used to conduct the test, workers must be trained in how to operate this device.

[0009] While the technology disclosed in the aforementioned Patent Document 1 does not require the preparation of a test specimen, it still requires a large-scale device, and mastery of the device is required for implementation. Furthermore, because part of the embedded sensor is exposed on the concrete surface, the probe connected to the sensor may get in the way during compaction and leveling work. Furthermore, removing the embedded sensor after the test may create a gap, which may affect leveling work.

[0010] In view of the above problems, the present invention has an object to provide a method for accurately estimating the strength development of a hydraulic composition using a simple method. Another object of the present invention is to provide a program executed for accurately estimating the strength development of a hydraulic composition using a simple method. [Means for solving the problem]

[0011] The method for estimating the strength development of a hydraulic composition according to the present invention comprises: Step (a) of taking a sample of a hydraulic composition to be poured in a pouring area or poured in the pouring area; (b) heating the sample under predetermined heating conditions; a step (c) of measuring a change in mass of the sample before and after the step (b); and (d) determining whether the hydraulic composition cast in the casting area has reached the strength development stage based on the measurement results in (c).

[0012] In this specification, the term "hydraulic composition" refers to a hardenable composition containing a cement composition and water, and includes both pre-hardened and hardened forms. In this specification, the term "cement composition" refers to a cement-containing powder or a material derived therefrom (a material derived from the powder in a water-containing mixture, or a hardened product thereof) that does not contain water, aggregate, or a water-reducing agent. Examples of hydraulic compositions include concrete and mortar.

[0013] As time passes, the hydraulic composition before hardening progresses as the hydration reaction progresses and hardening progresses. In other words, as the hardening of the hydraulic composition progresses, the amount of free water contained in the hydraulic composition decreases. The reduced free water is used in the hydration reaction and becomes bound water. Strictly speaking, the free water may temporarily increase immediately after pouring due to the bleeding phenomenon.

[0014] Free water is not bound to the cement composition and exists in a highly flexible state. Therefore, it evaporates when heated. On the other hand, bound water is bound to the atoms that make up the cement composition, so it does not evaporate even when heated.

[0015] According to the above method, a sample obtained by taking a portion of a hydraulic composition to be poured in a pouring area or that has already been poured in the pouring area is subjected to a heat treatment, and the change in mass before and after heating is measured. When the hydraulic composition after pouring contains a large amount of free water, in other words, when hardening has not progressed much, the amount of water that evaporates upon heating is large, so the change in mass of the sample before and after heating is relatively large. On the other hand, when the hydraulic composition after pouring contains a small amount of free water, in other words, when hardening has progressed, the amount of water that evaporates upon heating is small, so the change in mass of the sample before and after heating is relatively small.

[0016] Since the sample is obtained by sampling a portion of the hydraulic composition to be cast in the casting area or that has already been cast in the casting area, the degree of hardening of the sample over time can be considered to be the same as the degree of hardening of the hydraulic composition after casting. This allows the degree of hardening of the hydraulic composition after casting to be estimated based on the change in mass of the sample before and after heating. For example, if the amount or rate of change in mass is below a predetermined threshold, it can be determined that the hydraulic composition after casting has reached the strength development stage. Note that the sample may be mortar from which the coarse aggregate has been removed after sampling a portion of the hydraulic composition to be cast in the casting area or that has already been cast in the casting area.

[0017] When carrying out the step (a), the sample may be collected from the hydraulic composition that has actually been poured after the start of pouring work, or may be collected from the hydraulic composition to be poured before the start of pouring work, or may be collected by pooling a portion of the hydraulic composition to be poured before the start of pouring work, and then collecting the sample from the pooled hydraulic composition after the start of pouring work.

[0018] The step (b) may be a step of heating the sample using a dielectric heating device or an induction heating device. The dielectric heating device is typically a microwave oven. The induction heating device is typically an IH device.

[0019] An example of how to carry out the above method is as follows. First, the mass of the sample before heating is measured, and then the sample is placed in a microwave oven and heated at a predetermined output for a predetermined time. The sample is then removed from the microwave oven, i.e., the mass of the sample after heating is measured. The mass of the sample before heating is compared with the mass of the sample after heating to detect the degree of change. The degree of change may be the difference between the two (amount of change), or it may be the amount of change from a reference value or the ratio of the difference to the reference value. Here, the reference value may be the mass of the sample at the time pouring is completed.

[0020] That is, the step (c) may include a step (c1) of measuring the mass of the sample before the step (b) is performed, a step (c2) of measuring the mass of the sample after the step (b) is performed, and a step (c3) of calculating a difference value between the measurement result obtained in the step (c1) and the measurement result obtained in the step (c2), and the change in the mass of the sample may be measured based on the difference value obtained in the step (c3).

[0021] From the viewpoint of improving the accuracy of the estimation, it is preferable to measure the change in mass of the sample before and after heating at multiple points in time.

[0022] That is, in the estimation method, the steps (b) and (c) may be repeatedly executed multiple times at predetermined timings, and the step (b) may be a step of heating the sample under the heating conditions at each of the timings.

[0023] In this case, step (d) may be configured to determine that the hydraulic composition cast in the casting area has reached the time to develop strength if it is detected that the change in mass of the sample measured in step (c) shows a downward trend over time each time step (b) is performed and that the change in mass of the sample measured in step (c) is below a predetermined first threshold value.

[0024] The step (d) may include a step of estimating the strength development time when it is determined that the hydraulic composition cast in the casting area has not yet reached the strength development time.

[0025] More specifically, the estimation method includes a step (e) of acquiring a first data string showing a change in mass of a data-acquisition hydraulic composition, which is made with the same formulation as the hydraulic composition to be poured in the pouring area or which has been poured in the pouring area, before and after heating according to the elapsed time since water is mixed with the data-acquisition hydraulic composition, and a second data string showing a change in penetration resistance value of the data-acquisition hydraulic composition according to the elapsed time; and (f) deriving, from the first data string, a calibration curve showing the tendency of the transition of the amount of change in mass of the hydraulic composition for data acquisition during a time period including a time period before and after the strength determination time of the hydraulic composition for data acquisition, which is certified based on the second data string; The step (d) may include a step (d1) of estimating the time when the hydraulic composition cast in the casting area will reach the strength development time based on the change in mass of the sample measured in the step (c) and the calibration curve derived in the step (f) when it is determined that the hydraulic composition cast in the casting area has not yet reached the strength development time. This step (d1) corresponds to a step of predicting the strength development time of the hydraulic composition after casting.

[0026] When preparing the hydraulic composition for data acquisition, it may be finely adjusted to have the same conditions as the hydraulic composition after casting, taking into account climatic conditions such as temperature and humidity.

[0027] Step (e) corresponds to a step of acquiring the change in the degree of hardening over time for a hydraulic composition for data acquisition, which is made with the same composition as the hydraulic composition after casting. The data acquired in step (e) is stored in a predetermined storage area such as a server, and analyzed, for example, as data related to a calibration curve described later, to grasp the degree of hardening of a hydraulic composition made with the same composition as the hydraulic composition for data acquisition, and can be used at multiple work sites where the hydraulic composition with the same composition is cast.

[0028] In step (f), a calibration curve is derived from the data-collecting hydraulic composition, which is made with the same formulation as the hydraulic composition used at the casting site, showing the change in mass over time in the time period before and after the strength assessment. Data on this calibration curve is recorded in, for example, a predetermined memory unit.

[0029] The step (f) may be a step of deriving the calibration curve based on the first data sequence and the second data sequence transmitted from a shipping factory that ships the hydraulic composition to be poured into the pouring area. The shipping factory here is typically a ready-mixed concrete factory. In other words, the step (f) may be executed by a processing device such as a server or a terminal computer based on the first data sequence and the second data sequence transmitted from the ready-mixed concrete factory.

[0030] By comparing the data of this calibration curve with the change in mass of the sample measured in step (c), the time when strength appears can be easily estimated.

[0031] The data obtained in step (e) may be stored in a server, for example, and step (f) may be performed within the server. In this case, the server may be accessed on-site using a communication terminal (e.g., a smartphone, a notebook computer, a tablet computer, etc.) that can connect to the server, and information regarding the transition of the amount of change in the mass of the sample measured in step (c) may be input, so that calculation processing for estimating the time when strength develops may be performed on the server side.

[0032] As another example, data on the calibration curve may be stored on a server and downloaded to the communication terminal. In this case, information on the change in mass of the sample measured in step (c) may be input to the communication terminal, and the downloaded data on the calibration curve may be used to perform calculations for estimating the intensity onset time.

[0033] Furthermore, the step (d1) may be a step of estimating the time when the hydraulic composition cast in the casting area will reach the strength development time based on data on the calibration curve transmitted from a factory that ships the hydraulic composition to be cast in the casting area. In this case, the calibration curve may be derived in the ready-mixed concrete factory based on the first data string and the second data string, and then the step may be executed by a processing device such as a server or a terminal computer based on the data on the calibration curve transmitted from the ready-mixed concrete factory.

[0034] The present invention also provides a program for estimating the strength development of a hydraulic composition, which is installed in a processing device, and includes: a first process for calculating first information on the change in mass of a sample over time when the sample is a part of a hydraulic composition to be poured in a pouring area or has been poured in the pouring area and is subjected to a heat treatment; a second process for receiving input of second information on a calibration curve corresponding to a trend in the amount of change in mass of the hydraulic composition for data acquisition, which is made with the same formulation as the hydraulic composition to be poured in the pouring area or which has been poured in the pouring area, during a time period including before and after a time period for determining the strength of the hydraulic composition for data acquisition, when the hydraulic composition for data acquisition is subjected to a heat treatment; a third process for determining, by calculation, whether or not the hydraulic composition cast in the casting area has reached a strength development time based on the first information and the second information; and a fourth process for outputting the results obtained in the third process.

[0035] The processing device that performs the arithmetic processing using the above program may be one or more of the following: a notebook computer, a tablet computer, a smartphone, and a server.

[0036] The third process may include a process of estimating, by calculation, when it is determined that the hydraulic composition after casting has not yet reached its strength development time, the time when the hydraulic composition after casting will reach its strength development time, based on the change in mass of the sample described in the first information and the calibration curve described in the second information. Note that, when the calculation processing device is a server, the fourth process corresponds to a process of transmitting the results to a user's operation terminal (typically a portable computer or smartphone held by a worker present in the casting area). Also, when the calculation processing device is a user's operation terminal, the fourth process corresponds to a process of displaying the results on the display screen of the user's operation terminal. [Effects of the Invention]

[0037] According to the present invention, a method for accurately estimating the strength development of a hydraulic composition using a simple method is realized. [Brief explanation of the drawings]

[0038] [Figure 1]1 is a flowchart showing an example of the procedure for carrying out a method for estimating strength development of a hydraulic composition. [Figure 2] 1 is a block diagram schematically illustrating one configuration of a system for estimating the strength development time of a hydraulic composition. [Figure 3] 10 is a graph showing a schematic diagram of the change over time in the dehydration rate corresponding to the first data series and the penetration resistance value corresponding to the second data series. [Figure 4] FIG. 10 is a block diagram schematically showing another configuration of a system for estimating the strength development time of a hydraulic composition. [Figure 5] FIG. 10 is a block diagram schematically showing another configuration of a system for estimating the strength development time of a hydraulic composition. [Figure 6A] 1 is a graph showing the change over time in the penetration resistance value and dewatering rate of test mortar. [Figure 6B] 1 is a graph showing the change over time in the penetration resistance value and free water reduction rate of test mortar. DETAILED DESCRIPTION OF THE INVENTION

[0039] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for estimating the strength development of a hydraulic composition and a program for estimating the strength development of a hydraulic composition according to the present invention will be described with reference to the accompanying drawings.

[0040] Fig. 1 is a flowchart showing an example of the procedure for carrying out a method for estimating the strength development of a hydraulic composition according to the present invention (hereinafter, abbreviated as "this estimation method" where appropriate). In the following description, the step numbers assigned to the flowchart shown in Fig. 1 will be referred to where appropriate.

[0041] This estimation method is typically performed at the site where the hydraulic composition has been poured after the hydraulic composition has been poured, but the present invention does not limit the location where this estimation method is performed.

[0042] (Step S1: Sampling) A portion of the hydraulic composition cast at the casting location (within the casting area) is collected as a sample. This sample is used to estimate the strength development of the hydraulic composition at the casting location. When collecting the sample, it is preferable to collect a mortar sample by wet screening or removing coarse aggregate from the hydraulic composition cast at the casting location. Note that a portion of the hydraulic composition to be cast may also be collected as a sample before casting.

[0043] This sample is subjected to a heat treatment as described below, and the change in mass before and after heating is measured. Therefore, the amount of sample to be collected is arbitrary as long as it is an amount that allows the change in mass before and after heating to be detected.

[0044] Any method can be used for the heat treatment, but the simplest method is to use a dielectric heating device, such as a microwave oven. Considering that the sample will be heated in a microwave oven, the amount of sample to be collected is preferably 100 g to 600 g, and more preferably 150 g to 400 g. By using such an amount, it is possible to prevent the sample from exploding due to the internal moisture being heated by the induction heating device, and to improve the accuracy of measuring the change in mass before and after heating. Typically, a sample is collected in an amount of about 200 g ± 10 g.

[0045] In addition, in consideration of handling during the heat treatment in the next step, it is preferable to collect the sample on a paper plate, a magnetic container, or a heat-resistant container.

[0046] This step S1 corresponds to the process (a).

[0047] (Step S2: Measuring mass before heating) The mass of the sample collected in step S1 is measured. Any method for measuring mass can be used, but to ensure high accuracy, a mass measuring device such as an electronic balance can be used. The measured mass data is recorded in a memory unit installed in the mass measuring device or installed outside the mass measuring device.

[0048] In step S3 described later, if the sample is heated while placed in a container or the like, the mass may be measured with the sample placed in the container.

[0049] This step S2 corresponds to the process (c1).

[0050] (Step S3: Sample heating) The sample collected in step S1 is heated by a heating device. Any device can be used as the heating device, but it is preferable to heat the sample for as short a time as possible in order to prevent the sample from hardening during the heating process. From this perspective, a dielectric heating device such as a microwave oven or an induction heating device such as an IH device is preferably used as the heating device, and a dielectric heating device is more preferably used.

[0051] When heating a sample using a dielectric heating device, it is preferable to heat the sample in a heat-resistant container, for example, in order to improve ease of handling.

[0052] The heating time of the sample is set within a range in which the hardening of the hydraulic composition constituting the sample does not progress significantly during the heat treatment. When a dielectric heating device is used as the heating device, the heating time of the sample is, for example, about 3 to 6 minutes. The heating time is set appropriately depending on the value of the energy (power consumption) applied to the heat treatment.

[0053] This step S3 corresponds to the process (b).

[0054] (Step S4: Mass measurement after heating) In step S3, the mass of the sample after the heat treatment is measured. The mass can be measured by the same method as in step S2.

[0055] This step S4 corresponds to the process (c2).

[0056] (Step S5: Calculation of mass change before and after heating) The change in mass of the sample before and after the heat treatment is calculated based on the mass of the sample before the heat treatment obtained in step S2 and the mass of the sample after the heat treatment obtained in step S4. Simply, the difference between the mass of the sample before the heat treatment obtained in step S2 and the mass of the sample after the heat treatment obtained in step S4 is calculated. Alternatively, the change in mass before and after the heat treatment may be recognized by calculating the ratio of the masses before and after the heat treatment.

[0057] The calculation of the mass change may be performed by a processing unit or may be performed manually by an operator.

[0058] This step S5 corresponds to the process (c3). The steps S2, S4, and S5 correspond to the process (c).

[0059] Note that the procedure is not limited to the above steps S2 to S5, as long as the change in mass of the sample before and after the heat treatment can be measured. For example, the heat treatment and the mass measurement process may be carried out in parallel.

[0060] (Step S6: Determine when strength appears) Whether or not the sample has reached the strength development period is determined based on the results of the mass change of the sample before and after the heat treatment obtained in step S5. As described above, the sample is a sample taken from a portion of the hydraulic composition poured at the pouring location, so step S6 corresponds to the process of determining whether or not the hydraulic composition at the pouring location has reached the strength development period.

[0061] If the sample taken in step S1 is a hydraulic composition before hardening, it contains a large amount of free water. In this case, heating in step S3 evaporates some of the free water, and the measurement result in step S4 is significantly lower than the measurement result in step S2. On the other hand, if the sample taken in step S1 is a hydraulic composition whose hardening has progressed, much of the free water has changed into bound water. In this case, even when heated in step S3, the amount of water that evaporates is small, so the measurement result in step S4 does not show a significant change compared to the measurement result in step S2.

[0062] That is, as an example, if the change in mass of the sample before and after the heat treatment is below a predetermined first threshold Th1, it can be determined that the sample has reached the strength development period, and if the change in mass of the sample before and after the heat treatment is above a predetermined second threshold Th2 (Th2≧Th1), it can be determined that the sample has not yet reached the strength development period. When using this method, information regarding each threshold may be stored in advance in a memory unit of a communication terminal such as a smartphone or notebook computer of the operator.

[0063] Alternatively, it is possible to determine whether a sample has reached the strength development stage by taking into account the change in mass of the sample over time before and after heat treatment, as will be described later.

[0064] (Step S7: Post-processing) If it is determined in step S6 that the specimen has reached the time for developing strength (Yes in step S6a), a post-process is carried out at the pouring location. An example of the post-process is finishing work such as leveling work.

[0065] (Repeat steps S3 to S6) If it is determined in step S6 that the sample has not yet reached the strength development stage (No in step S6a), steps S3 to S6 are executed again after a predetermined waiting time. Note that in this case, the heating process in step S3 is performed under substantially the same heating conditions (power, time) as the previous heating process.

[0066] In this case, in step S6, in addition to the judgment criterion of whether the mass change of the sample before and after the heat treatment is below a predetermined first threshold value Th1, the judgment criterion may also include the tendency of the amount of mass change (amount of change) of the sample before and after the heat treatment to change over time.

[0067] As mentioned above, if not much time has passed since the hydraulic composition was poured into the pouring location, the sample will contain a large amount of free water. Therefore, when the heating treatment is performed in step S3, the amount of water evaporates according to the heating conditions. In other words, when step S3 is performed under the same heating conditions, it is expected that the amount of change in mass will show approximately the same tendency.

[0068] Immediately after pouring the hydraulic composition, bleeding may occur, causing a temporary increase in the amount of free water. In this case, it is expected that the change in mass will tend to increase.

[0069] On the other hand, after a certain amount of time has passed since the hydraulic composition was poured, the amount of free water decreases as the hydration reaction progresses and hardening progresses. In this case, the amount of water evaporated by the heat treatment in step S3 tends to decrease.

[0070] Therefore, if the change in mass before and after heating shows a decreasing trend over time and the change in mass of the sample before and after heat treatment is below a predetermined first threshold value Th1, it can be determined that the sample has reached the strength development period.

[0071] The timing at which steps S3 to S6 are repeatedly executed is arbitrary. However, if they are executed too close together, there is a possibility that the tendency of the obtained results will not change, while if the time interval is too long, there is a possibility that the hydraulic composition at the pouring point will be determined to have reached the strength development time at a time significantly later than the strength development time. From this perspective, the repetition time interval is preferably 10 to 60 minutes, and more preferably 15 to 30 minutes. Note that the repetition time interval does not need to be constant. For example, the repetition time interval may be set to be shorter as time passes from the start of pouring.

[0072] When repeatedly measuring the change in mass of the sample before and after heating, the sample may be collected each time, i.e., steps S1 to S6 may be repeatedly performed.

[0073] (Step S11: Estimation of strength onset time) If it is determined in step S6 that the sample has not yet reached the strength development stage (No in step S6a), it is also possible to optionally estimate the strength development stage of the sample. This point will be described with reference to FIG. 2 and subsequent drawings.

[0074] FIG. 2 is a block diagram showing a schematic configuration of a system having a function for estimating the intensity onset time.

[0075] The communication terminal 10 shown in FIG. 2 is a terminal that can be operated by a worker at the concrete pouring site, and is typically a smartphone, a notebook computer, or a tablet computer. The communication terminal 10 includes an input unit 11, a display unit 12, and a communication unit 13. The input unit 11 is a means for inputting information to the communication terminal 10, and is composed of an operator, keyboard, mouse, touch panel, or the like. The display unit 12 is a means for displaying information, and is, for example, a monitor. The communication unit 13 is a communication interface. Note that when information is input through the communication unit 13, the communication unit 13 may also function as the input unit 11.

[0076] The in-plant operation terminal 30 shown in Fig. 2 is an operation terminal installed in a factory (typically a ready-mixed concrete factory) that ships the hydraulic composition to the concrete pouring location, and is a computer of any type having a communication function. The in-plant operation terminal 30 includes an input unit 31 and a communication unit 32. The input unit 31 is a means for inputting information to the in-plant operation terminal 30. The communication unit 32 is a communication interface. When information is input through the communication unit 32, the communication unit 32 may also function as the input unit 31.

[0077] 2 is configured to be capable of communicating with the communication terminal 10 and the in-factory operation terminal 30 via the electric communication line 5, and includes a storage unit 21, an arithmetic processing unit 22, and a communication unit 23. The storage unit 21 is a storage medium such as a hard disk or memory. The arithmetic processing unit 22 is an arithmetic processing means such as a CPU. The communication unit 23 is a communication interface.

[0078] The memory unit 21 of the server 20 stores a first data string indicating the change in mass before and after heating over time since water was mixed into a data-acquiring hydraulic composition prepared with the same formulation as the poured hydraulic composition, and a second data string indicating the change in penetration resistance over time. Specifically, the first and second data strings obtained by measurements at the ready-mixed concrete plant are input to the in-plant operation terminal 30 via the input unit 31 and sent to the server 20 by the communication unit 32 via the telecommunications line 5. The server 20 receives the first and second data strings sent by the communication unit 23 and stores them in the memory unit 21. The telecommunications line 5 is, for example, the Internet, an intranet, or the like.

[0079] The first data string is obtained by carrying out the steps S2 to S5 described above at the ready-mixed concrete plant. The second data string is obtained by carrying out a method conforming to JIS A 1147 at the ready-mixed concrete plant. The steps for obtaining the first data string and the second data string can be carried out at a time before concrete pouring is carried out at the pouring location. The steps for obtaining the first data string and the second data string correspond to step (e).

[0080] 3 is a graph showing the change over time in the dehydration rate corresponding to the first data series and the penetration resistance value corresponding to the second data series. The "dehydration rate" here is a value defined as (A1-A2) / A0, where A0 is the mass of the hydraulic composition used for data acquisition at an initial stage (mortar state), A1 is the mass of the hydraulic composition used for data acquisition immediately before heating, and A2 is the mass of the hydraulic composition used for data acquisition after heating. In other words, the change over time in the dehydration rate corresponds to the first data series relating to the transition of the change in mass before and after heating depending on the time elapsed since water was mixed. The value of A1 may be the same as the value of A0.

[0081] The time when the hydraulic composition used for data acquisition starts to harden can be determined based on the value of the penetration resistance. Typically, the time when the slope of the curved second data string changes by a predetermined value or more can be determined as the time when hardening starts, i.e., the time when strength is developed. For example, in Figure 3, the time when the elapsed time tα is reached can be determined as the time when strength is developed.

[0082] A data string relating to the change in mass of the sample before and after heating (hereinafter referred to as "sample data string") is input to the communication terminal 10 via the input unit 11 in a state associated with the elapsed time since the start of the concrete pouring work. Specifically, the sample data string may be input by a worker at the concrete pouring site operating the communication terminal 10, or the sample data may be input by being automatically transferred to the communication terminal 10 from a mass measuring device such as an electronic balance.

[0083] The communication terminal 10 transmits the sample data string input via the input unit 11 to the server 20 from the communication unit 13 via the telecommunication line 5. The server 20 compares the sample data string received via the communication unit 23 with the first data string recorded in the memory unit 21, and calculates to estimate the behavior that the sample data string will exhibit in the future as time passes.

[0084] As described above, the first data string was obtained by performing the same processing as that used to obtain the sample data string on a data acquisition hydraulic composition made with the same formulation as the hydraulic composition after casting. Therefore, it is expected that the change in mass of the sample before and after heating will show approximately the same tendency as that of the first data string.

[0085] As described above, the server 20 can identify the intensity onset time in the first data sequence based on the second data sequence recorded in the storage unit 21. Therefore, the intensity onset time of the sample can be estimated based on the information about the intensity onset time in the first data sequence and the comparison result between the first data sequence and the sample data sequence. More specifically, the intensity onset time of the sample can be estimated by comparing the sample data sequence with a calibration curve obtained by associating the intensity onset time determined based on the second data sequence with the first data sequence. This estimation process is executed by the arithmetic processing unit 22 of the server 20. Alternatively, the server 20 may record information about the calibration curve in the storage unit 21, and the arithmetic processing unit 22 may compare the calibration curve read from the storage unit 21 with the sample data sequence received by the communication unit 23 to estimate the intensity onset time of the sample. The step of deriving data about the calibration curve corresponds to step (f).

[0086] The estimation result of the strength development time obtained by the calculation processing unit 22 is transmitted from the communication unit 23 to the communication terminal 10 via the electric communication line 5. The communication terminal 10 displays the estimation result received by the communication unit 13 on the display unit 12. This allows the worker at the pouring site to recognize the estimation result of the time when the hydraulic composition at the pouring site will develop strength.

[0087] When it is determined that the sample has not yet reached the strength development time, this step S11 of estimating the strength development time of the sample corresponds to the step (d1).

[0088] [Variations] A variety of modifications can be adopted for the system having the function of estimating the intensity onset time, as will be explained below.

[0089] <1> The calculation process for estimating the strength development time of the hydraulic composition at the pouring point may be performed on the communication terminal 10. Fig. 4 is a block diagram showing a schematic configuration of another system having a function for estimating the strength development time. In the embodiment shown in Fig. 4, the communication terminal 10 includes a calculation processing unit 14 and a memory unit 15.

[0090] In the modified example shown in FIG. 4 , the memory unit 21 of the server 20 also stores a first data string relating to the change in mass before and after heating according to the elapsed time since water was mixed in, for a hydraulic composition for data acquisition that was made with the same formulation as the hydraulic composition after casting, and a second data string showing the change in penetration resistance value according to the elapsed time.

[0091] In the communication terminal 10, a data string (sample data string) relating to the change in mass of the sample before and after heating is input from the input unit 11 in a state associated with the time elapsed since the start of the concrete pouring operation. In this modification, the communication terminal 10 receives the first data string and the second data string themselves recorded in the memory unit 21 of the server 20 from the communication unit 13, or data relating to the calibration curve, and records them in the memory unit 15. In the calculation processing unit 14, the communication terminal 10 compares the sample data string with the first data string recorded in the memory unit 15, and estimates the time when the strength of the sample will be developed.

[0092] <2> In a ready-mixed concrete plant, the first data string and the second data string may be directly input to the server 20 (see Figure 5). In other words, in Figure 2, the server 20 may also function as the in-plant operation terminal 30. In Figure 5, the server 20 is referred to as an "in-plant server" to clearly indicate that it is located within the ready-mixed concrete plant.

[0093] This embodiment can also be adopted in the alternative configuration of FIG.

[0094] [Another embodiment] In the above embodiment, the case of determining the time when the hydraulic composition at the casting location develops strength has been described, but the present invention can also be used to determine the time when the hydraulic composition at the casting location develops strength. Note that the time when the hydraulic composition at the casting location develops strength is included in the broad definition of the time when the hydraulic composition at the casting location develops strength. [Example]

[0095] The following description will be given with reference to examples.

[0096] Test mortars made from the materials shown in Tables 1 and 2 below were poured, and the penetration resistance was measured over a set time period using a method conforming to JIS A 1147. The results are shown in graphs (a) of Figures 6A and 6B. In Table 1, W / C refers to the water-cement ratio, and S / C refers to the sand-cement ratio.

[0097] [Table 1]

[0098] [Table 2]

[0099] Next, several 200g±10g samples of test mortar were placed on paper plates and placed in a 500W microwave oven for 4 minutes every hour. The change in mass before and after each heating treatment was measured, and the dehydration rate was calculated. As described above, the dehydration rate is a value defined as (A1-A2) / A0, where A0 is the mass at the initial stage (mortar state), A1 is the mass immediately before heating, and A2 is the mass after heating. The change in dehydration rate over time is shown in graph (b) of Figure 6A.

[0100] The free water reduction rate was calculated from the change in mass before and after heating when each heat treatment was carried out. The free water reduction rate is a value defined as (B1-B2) / B2, where B1 (=A1-A2) is the amount of water removed by the heat treatment and B2 is the theoretical amount of water contained in the test mortar estimated from the mix proportions. The value of B2 can be calculated from the values ​​in Table 1. That is, when the water-cement ratio W / C is 0.5 and the cement-sand ratio S / C is 2.8, the ideal amount of water B2 contained in 200 g of test mortar is: This can be calculated as 200 / (0.5+1+2.8)*0.5=23.3[g]. The change in the rate of decrease in free water over time is shown in graph (b) of FIG. 6B.

[0101] 6A(a) or 6B(a), it can be seen that the penetration resistance value shows an increasing trend from the point when the elapsed time reaches about 2 hours 30 minutes to 3 hours. As a result of intensive studies by the present inventors, it was found that the penetration resistance value is 0.3 N / mm 2 ~1.0N / mm 2 In other words, this time period corresponds to the strength development period and can be recognized as the leveling period. In addition, in Figures 6A and 6B, the penetration resistance value is 3.5 N / mm 2 The point at which the elapsed time reaches 4 hours and 22 minutes is marked as the "first train." According to the graph, the point at which the elapsed time reaches 4 hours and 22 minutes corresponds to the first train.

[0102] Figure 6A(b) confirms that the dehydration rate shows a decreasing trend during this strength development period. Figure 6B(b) also confirms that the free water reduction rate shows an increasing trend during this strength development period. Both graphs indicate that the test mortar is developing strength. [Explanation of symbols]

[0103] 5: Telecommunications lines 10: Communication terminal 11: Input section 12: Display section 13: Communications Department 14: Processing unit 15: Storage section 20: Server 21: Storage section 22: Processing unit 23: Communications Department 30: Factory operation terminal 31: Input section 32: Communications Department

Claims

1. Step (a) of taking a sample of a hydraulic composition to be poured in a pouring area or poured in the pouring area; a step (b) of heating the sample under predetermined heating conditions after the hydraulic composition has been cast in the casting area; a step (c) of measuring a change in mass of the sample before and after the step (b); and (d) determining whether the hydraulic composition cast in the casting area has reached the strength development stage based on the measurement results in the step (c).

2. The steps (b) and (c) are repeatedly performed multiple times at predetermined timings; The step (b) is a step of heating the sample under the heating conditions at the respective timings, The method for estimating the strength development of a hydraulic composition described in claim 1, characterized in that step (d) determines that the hydraulic composition cast in the casting area has reached the strength development time when it is detected that the change in mass of the sample measured in step (c) shows a downward trend over time each time step (b) is performed and that the change in mass of the sample measured in step (c) is below a predetermined first threshold.

3. The step (c) a step (c1) of measuring the mass of the sample before carrying out the step (b); a step (c2) of measuring the mass of the sample after the step (b); and a step (c3) of calculating a difference between the measurement result obtained in the step (c1) and the measurement result obtained in the step (c2), The method for estimating the strength development of a hydraulic composition according to claim 2, further comprising measuring a change in mass of the sample based on the difference value obtained in the step (c3).

4. a step (e) of acquiring a first data string showing the change in mass of a hydraulic composition for data acquisition, which is made with the same formulation as a hydraulic composition to be poured in the pouring area or which has been poured in the pouring area, before and after heating according to the elapsed time since water was mixed with the hydraulic composition, and a second data string showing the change in penetration resistance value of the hydraulic composition for data acquisition according to the elapsed time; and (f) deriving, from the first data string, a calibration curve showing a trend in the amount of change in mass of the hydraulic composition for data acquisition during a time period including a time period before and after a strength determination time period of the hydraulic composition for data acquisition, which is certified based on the second data string; The method for estimating the strength development of a hydraulic composition described in claim 2 or 3, characterized in that step (d) includes step (d1) of estimating the time when the hydraulic composition cast in the casting area will reach the strength development time based on the change in mass of the sample measured in step (c) and the calibration curve derived in step (f) when it is determined that the hydraulic composition cast in the casting area has not yet reached the strength development time.

5. The method for estimating the strength development of a hydraulic composition described in claim 4, characterized in that step (f) is a step of deriving the calibration curve based on the first data string and the second data string transmitted from a shipping factory that ships the hydraulic composition to be poured into the pouring area.

6. The method for estimating the strength development of a hydraulic composition described in claim 4, characterized in that step (d1) is a step of estimating the time when the hydraulic composition cast in the casting area will reach the strength development time based on data regarding the calibration curve sent from a shipping factory that ships the hydraulic composition to be cast in the casting area.

7. The method for estimating the strength development of a hydraulic composition according to any one of claims 1 to 6, characterized in that the step (b) is a step of heating the sample using a dielectric heating device or an induction heating device.

8. A program for estimating the strength development of a hydraulic composition, which is installed in a computing device, a first process for calculating first information on the change in mass of a sample over time when the sample is a part of a hydraulic composition to be poured in a pouring area or has been poured in the pouring area and is subjected to a heat treatment; a second process for receiving input of second information on a calibration curve corresponding to a trend in the amount of change in mass of a hydraulic composition for data acquisition, which is made with the same formulation as a hydraulic composition to be poured in the pouring area or which has been poured in the pouring area, during a time period including before and after a time period for determining the strength of the hydraulic composition for data acquisition, when the hydraulic composition for data acquisition is subjected to a heat treatment; a third process for determining, by calculation, whether or not the hydraulic composition cast in the casting area has reached a strength development time based on the first information and the second information; and a fourth process for outputting the results obtained in the third process.

9. The program for estimating the strength development of a hydraulic composition as described in claim 8, characterized in that the third process includes a process for estimating by calculation the time when the hydraulic composition cast in the casting area will reach the strength development time based on the change in mass of the sample described in the first information and the calibration curve described in the second information, when it is determined that the hydraulic composition cast in the casting area has not reached the strength development time.

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