Method, device and program for evaluating fresh concrete flowing through force-feed pipe

Abstract

To evaluate fresh concrete being pressure-fed by measuring impedance using an electrode sensor placed in a force-feed pipe to determine the paste volume.SOLUTION: Fresh concrete flowing through force-feed pipe is evaluated by: the steady state criterion that a paste volume is not changing and an aggregate mixing ratio of the fresh concrete is constant, based on impedance measurement values tending to be stable without variation in the impedance measurement by an electrode sensor 2; and the warning criterion that the aggregate mixing ratio of the fresh concrete is excessive in relative amount of coarse aggregate, based on the impedance measurement values tending to vary excessively in the impedance measurement by the electrode sensor, due to instability in the paste volume.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for evaluating the aggregate mixing ratio (ratio (G / S) of fine aggregate (S) to coarse aggregate (G)) of fresh concrete being pumped by performing impedance measurement using an electrode sensor placed in a pumping pipe, and to an evaluation device and program for the method. [Background technology]

[0002] In the past, when pouring concrete, there were cases where the separation of coarse aggregate due to lateral flow or the occurrence of peanut batter (junka) on the cover due to flow obstruction caused by reinforcing bars occurred. To deal with this, methods such as applying a vibrator according to well-defined rules or installing a wall vibrator have been used, but the occurrence of peanut batter (junka) on the concrete surface has not been completely eliminated.

[0003] In recent years, AC impedance measurement has come to be used for filling management during concrete pouring. It is known that impedance changes when the concrete mix is ​​different, and impedance measurement is being used to clarify the factors that affect the impedance of fresh concrete and to evaluate deviations of the aggregate mix ratio from the planned mix ratio.

[0004] For example, in the following Patent Document 1, the applicant has disclosed a method for evaluating the homogeneity of fresh concrete, in which one axis is set to impedance (Ω) and the other axis is set to 1 mm of concrete. 3 The paste volume (L / m) is defined as the sum of the volume of water and the volume of cement per 3We have proposed a method for evaluating the homogeneity of fresh concrete, in which a correlation diagram is obtained in which a paste volume target value is set based on a mix plan and an impedance target value corresponding to the paste volume target value is set based on the correlation, the impedance of the concrete is measured when the concrete is pumped or poured, and the deviation of the aggregate mixing ratio is estimated from the difference with the target impedance. Based on the above invention, the impedance of poured concrete is currently measured using electrode sensors installed in wall forms, etc., to monitor the separation of materials in fresh concrete. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-9814 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, all the experiments in the above Patent Document 1 were based on measuring the impedance of fresh concrete poured in a container, i.e., fresh concrete in a static state, and no verification was performed on how the impedance value of fresh concrete in a fluid state flowing in a pressure pipe changes according to changes in the aggregate mixing ratio. Therefore, it was unclear on what criteria and how to evaluate the impedance measurement results by the electrode sensor installed in the pressure pipe in order to grasp whether the aggregate mixing ratio in the pressure pipe is stable, whether the aggregate mixing ratio is starting to change, or whether the relative amount of coarse aggregate in the pressure pipe is excessive.

[0007] In addition, the concrete pumping pipe is made of metal, and depending on the position of the electrodes of the electrode sensor, there is a possibility that a short circuit of current may occur in the pumping pipe, which may hinder impedance measurement.

[0008] Therefore, a first object of the present invention is to provide a method for evaluating fresh concrete being pumped by measuring impedance using an electrode sensor placed in a pumping pipe and determining the paste volume.

[0009] A second object of the present invention is to provide a method for preventing a current short circuit from occurring in an electrode sensor for measuring impedance to a pressure pipe.

[0010] The third objective is to provide an evaluation device and program for evaluating fresh concrete. [Means for solving the problem]

[0011] In order to solve the first problem, the present invention relates to a method for measuring the impedance of fresh concrete by installing an electrode sensor on the wall of a pressure pipe and measuring the paste volume (1 m of concrete). 3 A method for evaluating fresh concrete flowing in a pumping pipe by determining the volume of water per unit area and the volume of cement per unit area, a steady state criterion for determining that the paste volume is unchanged and the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement value being stable without any variation in the impedance measurement by the electrode sensor; The present invention provides a method for evaluating fresh concrete flowing in a pressure pipe, characterized in that the method evaluates the aggregate mixing ratio of the fresh concrete by setting a warning criterion for judging that the relative amount of coarse aggregate is excessive due to instability of the paste volume when the impedance measurement values ​​tend to vary excessively in the impedance measurement by the electrode sensor.

[0012] In the invention described in claim 1 above, fresh concrete flowing in the pressure pipe is evaluated based on the steady state criterion and the warning criterion.

[0013] First, the steady state criterion for determining that the paste volume has not changed and the aggregate mixture ratio of fresh concrete (the ratio of fine aggregate to coarse aggregate) is constant based on the fact that the impedance measurement values ​​tend to be stable without variation in impedance measurement using the electrode sensor is based on the knowledge that, based on the experimental results described below, when the aggregate mixture ratio is within a certain range from the standard mix, it is presumed that the fine aggregate and coarse aggregate flow at a constant ratio, and it has been found that the impedance measurement value shows a constant value in such cases. Therefore, based on the fact that the impedance measurement values ​​tend to be stable without variation, it is determined that the paste volume has not changed and the aggregate mixture ratio of fresh concrete is constant.

[0014] Next, the warning criterion for judging that the relative amount of coarse aggregate in the aggregate mixture ratio of fresh concrete is excessive due to instability of the paste volume when the impedance measurement value shows an excessive tendency for variation in impedance measurement by the electrode sensor is based on the knowledge from the experimental results described below that when the proportion of coarse aggregate in fresh concrete increases excessively, the amount of fine aggregate which is relatively easy to flow decreases and the impedance measurement value becomes unstable in a jagged wave shape, and it was found that in such a case, the impedance measurement value appears to show a clear tendency for variation. Therefore, it is decided that the warning criterion for judging that the relative amount of coarse aggregate in the aggregate mixture ratio of fresh concrete is excessive due to instability of the paste volume when the impedance measurement value shows an excessive tendency for variation in impedance measurement.

[0015] As the present invention according to claim 2, there is provided a method for evaluating fresh concrete flowing in a pressure pipe as described in claim 1, which includes, as a precursor to the warning criterion, a preliminary warning criterion for determining that the paste volume is on a decreasing trend and the fresh concrete has a relatively increasing amount of coarse aggregate based on an increasing trend in impedance measurement by the electrode sensor.

[0016] The invention described in claim 2 above is provided with a preliminary warning criterion as a precursor to the warning criterion. Specifically, when the impedance measurement value by the electrode sensor shows an increasing trend, it is determined that the paste volume is decreasing and the fresh concrete has a relatively increasing coarse aggregate content. From the experimental results described below, it has become clear that when the mix balance is lost for some reason and the proportion of coarse aggregate begins to become relatively large, the impedance measurement value clearly shows an increasing trend. Therefore, when the impedance measurement value shows an increasing trend, it is determined that the paste volume is decreasing and the fresh concrete has a relatively increasing coarse aggregate content.

[0017] The present invention according to claim 3 provides a method for evaluating fresh concrete flowing in a pressure pipe according to either claim 1 or 2, in which the effective paste volume is calculated by subtracting the volume of the paste film (thickness α) adsorbed on the aggregate surface from the paste volume, instead of the paste volume.

[0018] In the invention described in claim 3, since it is assumed that the paste film adsorbed on the aggregate surface is not involved in ion induction, it is possible to improve the correlation with impedance (Ω) by subtracting the volume of this paste film from the paste volume.

[0019] According to a fourth aspect of the present invention, there is provided a method for evaluating fresh concrete flowing in a pressure pipe according to the first aspect, in which a digital signal of a voltage between the electrodes of the electrode sensor is measured instead of measuring the impedance.

[0020] The invention described in claim 4 above is a method for measuring impedance in indoor experiments by connecting an LCR meter to the electrodes. However, since it is difficult to measure impedance using precision equipment such as an LCR meter in adverse environments such as construction sites, the invention is devised to simply substitute voltage and measure the digital signal of the voltage between the electrodes of the electrode sensor.

[0021] The present invention according to claim 5 provides a method for evaluating fresh concrete flowing in a pressure pipe as described in claim 1, in which the electrode sensor prevents a short circuit of current by ensuring a distance of 6 mm or more between the electrode and the pressure pipe using an insulator.

[0022] The invention described in claim 5 above is such that, in order to prevent current short-circuiting and improve measurement accuracy when measuring impedance, a separation of 6 mm or more is ensured between the electrode and the pressure pipe using an insulator based on the experimental results described below.

[0023] According to the present invention as claimed in claim 6, a paste volume (1 m of concrete) is calculated based on a signal from an electrode sensor for measuring the impedance of fresh concrete installed on the wall of the pressure pipe. 3 The evaluation device evaluates fresh concrete flowing in a pressure pipe by grasping the volume of water per unit volume and the volume of cement per unit volume, a steady state criterion for determining that the paste volume is unchanged and the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement value being stable without any variation in the impedance measurement by the electrode sensor; The present invention provides an evaluation device that evaluates fresh concrete flowing in a pressure pipe by using a warning criterion that judges that the relative amount of coarse aggregate in the aggregate mixing ratio of fresh concrete is excessive due to instability of the paste volume when the impedance measurement value tends to vary excessively in the impedance measurement by the electrode sensor.

[0024] According to the present invention as claimed in claim 7, a computer is provided for calculating the paste volume (1 m of concrete) based on a signal from an electrode sensor for measuring the impedance of fresh concrete installed on the wall of the pressure pipe. 3 The program is for functioning as a means for evaluating fresh concrete flowing in a pressure pipe by grasping the volume of water per unit volume and the volume of cement per unit volume, The computer is made to function as a steady state standard judgment means for judging that the paste volume has not changed and that the aggregate mixing ratio of the fresh concrete is constant when the impedance measurement values ​​by the electrode sensor tend to be stable without variation, and as a warning standard judgment means for judging that the aggregate mixing ratio of the fresh concrete has an excessive relative amount of coarse aggregate due to instability of the paste volume when the impedance measurement values ​​by the electrode sensor tend to vary excessively, thereby evaluating fresh concrete flowing through a pressure pipe. Effect of the Invention

[0025] As described above in detail, according to the present invention, impedance measurement is performed using an electrode sensor disposed in the pressure pipe, and it is possible to correctly evaluate the aggregate mixing ratio of fresh concrete being pressure-fed.

[0026] It is also possible to prevent current short-circuiting of the electrode sensor for measuring impedance to the pressure pipe.

[0027] Furthermore, it is possible to provide an evaluation device and a program for evaluating fresh concrete. [Brief description of the drawings]

[0028] [Figure 1] 1 shows the attachment state of an electrode sensor 2 to a pressure pipe 1, (A) is a cross-sectional view, (B) is a vertical cross-sectional view (viewed in the direction of the arrow BB), and (C) is a top view from a horizontal cross-section (viewed in the direction of the arrow CC). [Diagram 2] (A) is a current diagram when there is a short circuit, and (B) is a current diagram when there is no short circuit. [Diagram 3] 1A and 1B show a test apparatus used in Example 1, in which (A) is a cross-sectional view and (B) is a plan view. [Figure 4] 1A to 1C are front views of four types of electrode sensors with different electrode areas used in Example 1. [Diagram 5]FIG. 11 is an explanatory diagram of a digital signal value of a voltage substituted for impedance. [Figure 6] 6A to 6D are graphs showing the experimental results in Example 1, showing the relationship between the separation distance and the voltage digital signal value for each of four types of electrode sensors. [Figure 7] FIG. 11 is a perspective view showing a test device used in Example 2. [Figure 8] 13 shows graphs (A) to (D) of the time and voltage digital signal value for each blend, which are the experimental results (part 1) in Example 2. [Figure 9] 13 shows graphs (A) to (D) of the time and voltage digital signal value for each blend, which are the experimental results (part 2) in Example 2. [Figure 10] 13 shows graphs (A) to (D) of the time and voltage digital signal value for each blend, which are the experimental results (part 3) in Example 2. [Figure 11] FIG. 1 is a correlation diagram between impedance and paste volume in a static state (no flow). [Figure 12] FIG. 1 is a correlation diagram between impedance and effective paste volume in a static state (no flow). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0030] [Relationship between impedance and paste volume in static state] First, the relationship between impedance and paste volume in a static state (without flow) will be described. This content is the content described in JP 2023-9814 A.

[0031] Although the concrete mix itself is properly mixed with the water, cement, coarse aggregate, and fine aggregate according to the initial mix plan (mix design), the concrete does not have a uniform consistency because the mixture ratio of coarse aggregate and fine aggregate varies from place to place. Therefore, it is necessary to know the mixture ratio of aggregate when pouring the concrete, and the following procedure makes it possible to estimate deviations in the mixture ratio of aggregate.

[0032] In advance, one axis is set to impedance (Ω) and the other axis is set to 1m of concrete. 3 The paste volume (L / m) is defined as the sum of the volume of water and the volume of cement per 3 ) A correlation diagram is obtained, and a paste volume target value is set based on the formulation plan in the correlation diagram, and an impedance target value corresponding to the paste volume target value is set based on the correlation, The impedance of the concrete is measured when the concrete is pumped or poured, and the deviation of the aggregate mixing ratio is estimated from the difference between the impedance and the target impedance.

[0033] That is, prior to pouring concrete, a laboratory experiment was conducted, for example, with the vertical axis representing impedance (Ω) and the horizontal axis representing the impedance of 1 m of concrete. 3 The paste volume (L / m) is defined as the sum of the volume of water and the volume of cement per 3 In this correlation diagram, both the vertical and horizontal axes are logarithmic.

[0034] The "paste volume" is a factor that the present inventors have focused on. When concrete is composed of water, cement, coarse aggregate, and fine aggregate, it is believed that the volume of the cement paste excluding the coarse aggregate and fine aggregate is largely related to the induction of ions, and therefore the volume involved in the induction of ions is calculated based on the volume of 1 m of concrete. 3 The "paste volume" is defined as the sum of the volume of water and the volume of cement per unit area.

[0035] The paste volume (L / m3 ) can be calculated by the following formula (1).

number

[0036] Paste volume (L / m 3 )=170(kg / m 3 ) / 1000(kg / m 3 )+293(kg / m 3 ) / 3160(kg / m 3 ) =0.170(m 3 / m 3 )+0.093(m 3 / m 3 )=0.263(m 3 / m 3 )=263(L / m 3 ) Figure 11 shows the relationship between impedance (Ω) and paste volume (L / m 3 ) is shown, and to explain in detail based on this, the amounts of water, cement, coarse aggregate, and fine aggregate are clear based on the mix plan. Therefore, the paste volume can be calculated and the target paste volume value is clear. In addition, taking into consideration the variation in the aggregate mixing ratio, the target paste volume value is set as the median and a predetermined allowable range is set in the ± direction. It is desirable to set this allowable range based on experience and experiments. In general, it is desirable to set the target paste volume value as the median within a range of ±25% of the target paste volume value, preferably within a range of ±20%. As will be described later, on the paste volume axis, a decrease in paste volume compared to the target paste volume value means that there is relatively more coarse aggregate, and an increase in paste volume compared to the target paste volume value means that there is relatively more fine aggregate.

[0037] Therefore, by measuring the impedance of concrete and estimating the deviation of the aggregate mixture ratio from the difference between the measured impedance and the target impedance, it is possible to estimate in which direction the aggregate mixture ratio (ratio of coarse aggregate to fine aggregate) is biased.

[0038] Impedance (Ω) and paste volume (L / m 3 12, in order to further improve accuracy, the paste volume in the correlation diagram can be replaced with the effective paste volume obtained by subtracting the volume of the paste film (thickness α) adsorbed on the aggregate surface from the paste volume. Since the paste film adsorbed on the aggregate surface is assumed not to be involved in ion induction, by subtracting the volume of this paste film from the paste volume, it becomes possible to further improve the correlation with impedance (Ω), and to improve accuracy.

[0039] [Relationship between impedance and paste volume in a fluid state] Next, a method for evaluating fresh concrete flowing through a pressure pipe by installing an electrode sensor for measuring the impedance of fresh concrete in the pressure pipe will be described in detail.

[0040] In the above [Relationship between impedance and paste volume in a static state], it was found that in a static state, using the impedance of the standard mix as a reference, when the measured impedance increases it means that the amount of coarse aggregate has relatively increased, and when the measured impedance decreases it means that the amount of coarse aggregate has relatively decreased (= the amount of fine aggregate has relatively increased), but no verification has been done on how the impedance value of fresh concrete in a fluid state flowing inside the pumping pipe changes in response to changes in the aggregate mixture ratio. Therefore, with regard to fresh concrete in a fluid state, it is important to understand the paste volume from the measured impedance and infer the state of the aggregate mixture ratio.

[0041] The following will explain this in detail with reference to the drawings.

[0042] First, as shown in Fig. 1, an electrode sensor 2 is installed on the wall of a pressure pipe 1 to measure the impedance of fresh concrete. The electrode sensor 2 is connected to a computer that serves as a fresh concrete evaluation device 5, and the signal from the electrode sensor is A / D converted and then input to the evaluation device 5, where the properties of the fresh concrete are evaluated by an evaluation program.

[0043] Since the material of the pressure pipe 1 is metal, there is a possibility that a current short circuit may occur from the electrode 3. Specifically, as shown in Fig. 2(A), if a current short circuit occurs from the point electrode, the short circuit current flows through the pressure pipe 1, making highly accurate measurement impossible. Fig. 2(B) shows the state of the current line when there is no current short circuit.

[0044] Therefore, in order to prevent a short circuit of the current, it is desirable to ensure a separation S of 1 mm or more, preferably 6 mm or more, between the electrode and the pressure pipe, using an insulator, in accordance with the experimental example described later. In the illustrated example, a plastic insulator 4 is provided so as to surround the periphery of the protrusion in which the electrodes 3, 3 of the electrode sensor 2 are embedded. The electrode sensor 2 is attached to the top surface of the pressure pipe 1 in the illustrated example, but it may be attached to the side surface or bottom surface, or multiple sensors may be provided.

[0045] This method for measuring the impedance of the fresh concrete flowing through the pressure pipe 1 and evaluating the fresh concrete flowing through the pressure pipe is based on the following criteria.

[0046] a steady state criterion for determining that the paste volume is unchanged and the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement value being stable without any variation in the impedance measurement by the electrode sensor; If the impedance measurement value in the impedance measurement by the electrode sensor shows a tendency for excessive variation, a warning criterion is set to determine that the aggregate mixing ratio of the fresh concrete has an excessive relative amount of coarse aggregate due to instability in the paste volume.

[0047] According to the experimental results described later, when the aggregate mixture ratio is within a certain range from the standard mixture ratio, the impedance measurement results are measured at a constant value continuously without variation, and it is presumed that the fine aggregate and coarse aggregate are flowing at a constant ratio. Therefore, when the impedance measurement value tends to be stable without variation in the impedance measurement by the electrode sensor, it can be determined that the aggregate mixture ratio is constant and the mixture state of fresh concrete is constant.

[0048] Next, the warning criterion for determining that the relative amount of coarse aggregate in the aggregate mixture ratio of fresh concrete is excessive due to instability of the paste volume when the impedance measurement value by the electrode sensor shows an excessive tendency to vary is that, according to the experimental results described below, when the amount of relatively flowable fine aggregate in fresh concrete decreases and the amount of coarse aggregate increases excessively, the coarse aggregate, which is a non-conductive material, becomes dense, and there are alternating periods when there is a lot of coarse aggregate and air and periods when the concrete is rich in mortar, causing excessive variation in the impedance measurement values, resulting in the paste volume becoming unstable and the impedance measurement values ​​showing a clear tendency to vary. Therefore, the warning criterion for determining that the relative amount of coarse aggregate in the aggregate mixture ratio of fresh concrete is excessive when the impedance measurement value shows an excessive tendency to vary is set as follows.

[0049] As a precursor to the above warning criteria, it is desirable to provide a preliminary warning criterion that, when the impedance measurement value by the electrode sensor shows an increasing trend, determines that the paste volume is on a decreasing trend and that the fresh concrete has a relatively increasing amount of coarse aggregate.

[0050] The preliminary warning criterion is a warning criterion for the initial state where the paste volume is beginning to change. Experimental results described later have revealed that when the mix balance is lost for some reason and the proportion of coarse aggregate begins to increase relatively, the impedance measurement value clearly shows an increasing trend. Therefore, when the impedance measurement value shows an increasing trend, it is determined that the paste volume is decreasing and the amount of coarse aggregate in fresh concrete is relatively increasing. EXAMPLES

[0051] Example 1 Example 1 is an experiment conducted to determine the appropriate value of the separation distance S between the electrode 3 of the electrode sensor 2 installed in the pressure pipe 1 and the pressure pipe 1 in order to prevent current short circuiting of the electrode sensor 2 for measuring impedance to the pressure pipe 1 and to perform accurate impedance measurement.

[0052] (1) Experimental overview As shown in Figure 3, a container was created using a wooden formwork with an open top and inner dimensions of 300 mm (length) × 300 mm (width) × 300 mm (height). A hole (φ35 mm) was formed in the center of the bottom surface of the formwork to allow the electrode sensor to be replaced. To investigate the separation distance at which current crosstalk does not occur, thin steel plates with a thickness of 1.2 mm and holes of φ35, 45, 60, 80, and 100 mm were prepared as thin steel plates to be placed on the bottom surface of the formwork. These thin steel plates correspond to separation distances S of 1 mm, 6 mm, 13.5 mm, 23.5 mm, and 33.5 mm, respectively.

[0053] As the electrode sensors, four types were prepared, with point electrodes having dimensions of φ6 mm, φ9 mm, φ11.5 mm, and a bow shape, as shown in Fig. 4. The mix proportion of fresh concrete used was C1-3 (standard mix proportion) of Experimental Example 2 described later.

[0054] In the experiment, fresh concrete was filled while changing the thin steel plate for each electrode sensor, and the impedance was measured by the electrode sensor.

[0055] Normally, impedance is measured by connecting an LCR meter to the electrodes, but since it seems difficult to measure impedance using precision equipment such as an LCR meter in adverse environments such as construction sites, we have simplified the measurement by using voltage instead. Specifically, as shown in Figure 5, (1) a reference resistor Z2 is connected in series to the electrodes. (2) When a voltage E is applied to a series circuit of resistors Z1 and Z2, the voltage V1 between the electrodes is measured by utilizing the fact that the voltage is distributed in proportion to the magnitude of the electrical resistance. (3) Various trials are made of the value of the reference resistor Z2 until the voltage V1 can be measured at an appropriate magnitude. (4) Voltage V1 is output as a voltage digital signal that is a relative value when the applied voltage E is divided by 10 bits.

[0056] (2) Experimental results The experimental results are shown in Figure 6. For each electrode sensor, it was found that the voltage digital signal had an upward trend up to a separation distance of 6 mm, but once the separation distance exceeded 6 mm it became almost horizontal, the same as in the case without the iron plate. This shows that a separation distance of 6 mm or more can prevent current crosstalk.

[0057] Therefore, when attaching the electrode sensor 2 to the pressure pipe 1, it is desirable to ensure a separation of 6 mm or more between the electrode 3 and the pressure pipe 1 by the insulator 4.

[0058] Example 2 This experiment was conducted to measure impedance using an electrode sensor 2 placed in a pressure pipe 1 in order to correctly evaluate the paste volume of the fresh concrete being pressure-fed, that is, the aggregate mixing ratio at the time of flow.

[0059] (1) Experimental overview A rigid vinyl chloride pipe VU125 (inner diameter 131 mm × outer diameter 140 mm) with a length of 2000 mm was prepared, and an electrode sensor (electrode: bow shape) was attached to the tip side. After filling fresh concrete into this rigid vinyl chloride pipe in an inclined state, it was set vertically and then slowly pulled up to discharge the fresh concrete inside, and the voltage digital signal during discharge was measured by the electrode sensor.

[0060] The fresh concrete was of 5 types shown in Table 1 below. Also, its volume composition ratio is shown in Table 2 below. C1-3 in the center is the standard mixture, and the mixture has an increasing relative amount of coarse aggregate as going up (coarse aggregate amount: C1-3 < C1-2 < C1-1), and a decreasing relative amount of coarse aggregate as going down (coarse aggregate amount: C1-3 > C1-4 > C1-5).

[0061]

Table 1

[0062]

Table 2

[0063] (2) Experimental results <Experimental result 1> The results of the first experiment are shown in Fig. 8. Note that C1-5 is omitted because it has the same tendency as C1-4.

[0064] First, in the case of the standard mixture C1-3 shown in Fig. 8(C), the impedance measurement results show that a constant value is continuously measured without variation, so it is presumed that the fine aggregate and the coarse aggregate are flowing while maintaining a certain ratio.

[0065] In the case of C1-2 mix shown in Figure 8(B), the impedance measurement value shows a clear tendency to increase from the middle of the flow. The reason for this tendency is that when the PVC pipe is tilted and fresh concrete is filled in, the fine aggregate (actually the mortar) flows downwards through the gaps between the coarse aggregates, resulting in a mix with more fine aggregate at the bottom and more coarse aggregate at the top, and when the PVC pipe is pulled upwards, the electrode sensor reliably captures this change in the aggregate mix ratio. Considering that this tendency to increase in the impedance measurement value only occurs in the case of C1-2 mix, it is surmised that a phenomenon in which the balance between coarse aggregate and fine aggregate is easily lost occurs within a certain range of aggregate mix ratios.

[0066] In the case of the C1-1 mix shown in Figure 8(A), the impedance measurement values ​​show a tendency for excessive variation. The reason for this tendency is believed to be that the amount of relatively easy-to-flow fine aggregate in fresh concrete is reduced and the proportion of coarse aggregate is excessively increased, causing the non-conductive coarse aggregate to become dense, resulting in excessive variation in the impedance measurement values ​​due to alternating periods of high coarse aggregate and air content and periods of mortar richness, which makes the paste volume unstable and causes the impedance measurement values ​​to show an excessive tendency for excessive variation.

[0067] <Experimental Results 2 and 3> The results of the second experiment shown in FIG. 9 and the results of the third experiment shown in FIG. [Explanation of symbols]

[0068] 1...pressure pipe, 2...electrode sensor, 3...electrode, 4...insulator, 5...evaluation device (computer)

Claims

1. An electrode sensor was installed on the wall of the pressure pipe to measure the impedance of fresh concrete, and the paste volume (1 m of concrete) was 3 A method for evaluating fresh concrete flowing in a pumping pipe by determining the volume of water and the volume of cement per unit area, a steady state criterion for determining that the paste volume is unchanged and the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement value being stable without any variation in the impedance measurement by the electrode sensor; A method for evaluating fresh concrete flowing in a pressure pipe, characterized in that when impedance measurement values ​​using the electrode sensor show a tendency for excessive variation, a warning criterion is set to determine that the aggregate mixing ratio of the fresh concrete has an excessive relative amount of coarse aggregate due to instability in the paste volume.

2. 2. The method for evaluating fresh concrete flowing in a pressure pipe as described in claim 1, further comprising a preliminary warning criterion for determining that the paste volume is on a decreasing trend and the fresh concrete has a relatively increasing amount of coarse aggregate based on an increasing trend in impedance measurement by the electrode sensor, as a precursor to the warning criterion.

3. 3. A method for evaluating fresh concrete flowing in a pressure pipe as described in claim 1 or 2, wherein the paste volume is replaced by an effective paste volume obtained by subtracting the volume of the paste film (thickness α) adsorbed on the aggregate surface from the paste volume.

4. The method for evaluating fresh concrete flowing in a pressure pipe according to claim 1, wherein a digital signal of a voltage between the electrodes of the electrode sensor is measured instead of measuring the impedance.

5. 2. The method for evaluating fresh concrete flowing through a pressure pipe according to claim 1, wherein in the electrode sensor, a short circuit of current is prevented by ensuring a distance of 6 mm or more between the electrode and the pressure pipe using an insulator.

6. Based on the signal from the electrode sensor for measuring the impedance of fresh concrete installed on the wall of the pressure pipe, the paste volume (1 m of concrete) was calculated. ３ The evaluation device evaluates fresh concrete flowing in a pressure pipe by grasping the volume of water per unit area and the volume of cement per unit area, a steady state criterion for determining that the paste volume is unchanged and the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement value being stable without any variation in the impedance measurement by the electrode sensor; The evaluation device is characterized by evaluating fresh concrete flowing through a pressure pipe using a warning criterion that determines that the relative amount of coarse aggregate in the aggregate mixture ratio of fresh concrete is excessive due to instability in the paste volume when the impedance measurement values ​​tend to vary excessively in the impedance measurement using the electrode sensor.

7. A program for making a computer function as a means for evaluating fresh concrete flowing in a pressure pipe by determining the paste volume (the sum of the volume of water and the volume of cement per 1 m3 of concrete) based on a signal from an electrode sensor for measuring the impedance of fresh concrete installed on the wall of the pressure pipe, The program is characterized by causing the computer to function as a steady state standard judgment means for judging that the paste volume has not changed and that the aggregate mixing ratio of the fresh concrete is constant based on the impedance measurement values ​​tending to be stable without variation in the impedance measurement by the electrode sensor, and as a warning standard judgment means for judging that the aggregate mixing ratio of the fresh concrete has an excessive relative amount of coarse aggregate due to instability in the paste volume based on the impedance measurement values ​​tending to vary excessively in the impedance measurement by the electrode sensor, and evaluating the fresh concrete flowing through a pressure pipe.

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