Method for fluidizing ready-mixed concrete

Abstract

To provide a method for fluidizing ready-mixed concrete by which the ready-mixed concrete can be extremely easily and uniformly fluidized.SOLUTION: A method for fluidizing ready-mixed concrete includes a measuring process for measuring a degree of repulsion at a plurality of positions of a plurality of hardened test concretes having different vibration times, a calculating process for calculating a standard deviation for each of the plurality of hardened test concretes having different vibration times from a plurality of measurement results of the degree of repulsion, a selecting process for selecting a vibration time of the hardened test concrete having the smallest standard deviation as a standard vibration time, a first preparatory process for acquiring first inclination information corresponding to the first posture and second inclination information corresponding to the second posture after the standard vibration time elapses by an acquisition unit while a measurement sensor moves from a first posture to a second posture, and a vibrating process for applying a vibrator to placed ready-mixed concrete and vibrating the vibration time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for fluidizing ready-mixed concrete. [Background technology]

[0002] A method for determining the completion of concrete compaction is known (see Patent Document 1). In this method, a float is placed at the bottom of a form before concrete is poured, and completion of concrete compaction is determined when the float rises.

[0003] A method for determining the degree of compaction of concrete is known (see Patent Document 2). This method is said to be able to determine the degree of compaction of concrete by irradiating the concrete with radiation.

[0004] A measuring device and a method for determining the compaction of concrete are known (see Patent Document 3). In this measuring device, an acceleration sensor is placed inside a rod-shaped housing, and the acceleration sensor can detect vibrations transmitted to the concrete. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-183392 [Patent Document 2] Japanese Patent Application Publication No. 2019-143399 [Patent Document 3] Patent No. 6503260 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] In the method for determining the completion of concrete compaction in Patent Document 1, the floaters are placed at a pitch of 50 cm, but for a structure with a width of 10 m, at least 19 floaters are required, which poses the problem of large-scale preparation.In addition, if the floaters do not rise to the surface due to the influence of aggregate in the concrete, they cannot be recovered.

[0007] The method of determining the degree of compaction of concrete in Patent Document 2 has a problem in that the number of counts of measured radiation varies, making it difficult to determine the degree of compaction in real time.

[0008] In the measuring device and determination method of Patent Document 3, because the housing has a fixed volume, it is necessary to continue vibration after removing the housing and fill the resulting hollow space with fresh concrete to perform compaction. As a result, the concrete around the area where compaction is determined to be complete is subjected to excessive compaction.

[0009] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for fluidizing ready-mixed concrete that can fluidize ready-mixed concrete extremely simply and uniformly. [Means for solving the problem]

[0010] The above-mentioned problems are solved by the present invention. That is, the method for fluidizing ready-mixed concrete according to the present invention (1) comprises: A method for fluidizing ready-mixed concrete using an evaluation device having a measurement sensor including a weight portion, a float portion on which a buoyancy greater than that of the weight portion acts, and a sensor portion characterized by detecting a change in inclination of a line segment connecting the weight portion and the float portion relative to a vertical direction, and an acquisition portion that acquires the change in inclination, a measuring step in which the degree of rebound is measured at a plurality of points on a plurality of hardened test concrete samples that have been vibrated by a vibrator for different vibration times before hardening; a calculation step of calculating a standard deviation for each of the plurality of hardened test concretes having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete that minimizes the standard deviation; a first preliminary step of installing the measurement sensor in a first posture in which the float portion is positioned lower than the weight portion in the test ready-mixed concrete, and inserting the vibrator near the measurement sensor; a second preliminary step of operating the vibrator to vibrate the test ready-mixed concrete to fluidize the test ready-mixed concrete, and acquiring, as the test ready-mixed concrete fluidizes, first tilt information corresponding to the first position and second tilt information corresponding to after the standard vibration time has elapsed while the measurement sensor moves from the first position to a second position in which the float portion is positioned above the weight portion, or while the measurement sensor is midway from the first position to the second position; a vibration step of introducing a vibrator into the poured fresh concrete to vibrate it for the standard vibration time; Equipped with In the vibration process, the measurement sensor is placed in the poured fresh concrete in the first attitude, and the vibrator vibrates for the standard vibration time until the tilt change obtained by the acquisition unit changes from the first tilt information to the second tilt information.

[0011] In addition, the method for fluidizing ready-mixed concrete of the present invention (2) is a measuring step in which the degree of rebound is measured at a plurality of points on a plurality of hardened test concrete samples that have been vibrated by a vibrator for different vibration times before hardening; a calculation step of calculating a standard deviation for each of the plurality of hardened test concretes having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete that minimizes the standard deviation; a vibration step of introducing a vibrator into the poured fresh concrete to vibrate it for the standard vibration time; Equipped with. [Effects of the Invention]

[0012] According to the present invention, a method for fluidizing ready-mixed concrete can be provided that can fluidize ready-mixed concrete extremely simply and uniformly. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing an evaluation device used in a ready-mixed concrete fluidization method according to an embodiment. FIG. [Figure 2] 2 is a cross-sectional view showing a state in which a measurement sensor of the evaluation device shown in FIG. 1 is installed inside a concrete formwork. FIG. [Figure 3] 2 is an enlarged front view showing a measurement sensor of the evaluation device shown in FIG. 1. FIG. [Figure 4] 4 is a cross-sectional view of the measurement sensor shown in FIG. 3 taken along the line F4-F4. [Figure 5] 4 is a schematic diagram showing a process in which the measurement sensor shown in FIG. 3 moves from a first posture to a second posture via an intermediate posture. [Figure 6] FIG. 2 is a perspective view showing the outer shape and dimensions of hardened test concrete used in the measurement step of the ready-mixed concrete fluidization method of the embodiment. [Figure 7] FIG. 7 is a plan view showing the position where a vibrator is inserted and the positions of the first and second sides where the degree of resilience is measured for the hardened test concrete shown in FIG. 6 in the state of fresh concrete before hardening. [Figure 8] FIG. 7 is a front view showing side points (grid points) for measuring the degree of rebound on a first side surface of the hardened test concrete shown in FIG. 6. [Figure 9] FIG. 7 is a side view showing the side points (grid points) at which the degree of rebound is measured on the second side of the hardened test concrete shown in FIG. 6. [Figure 10] 1 is a graph showing the resilience of hardened fresh concrete when the vibrator is vibrated for 2 to 3 seconds and the regression line obtained therefrom. [Figure 11] 1 is a graph showing the resilience of hardened fresh concrete when vibrated by a vibrator for 20 seconds and the regression line obtained therefrom. [Figure 12] 1 is a graph showing the resilience of hardened fresh concrete when vibrated by a vibrator for 50 seconds and the regression line obtained therefrom. [Figure 13] 13 is a graph showing the relationship between the absolute value of the slope of the regression line shown in FIGS. 10 to 12 and the vibration time. [Figure 14] 13 is a graph showing the standard deviation of the degree of repulsion for each hardened fresh concrete with different vibration times obtained from FIGS. 10 to 12, etc.; DETAILED DESCRIPTION OF THE INVENTION

[0014] The evaluation device for evaluating the degree of fluidity of ready-mixed concrete and the method for fluidizing ready-mixed concrete using the same according to the present invention will be described below with reference to the drawings. [Embodiment]

[0015] As shown in FIGS. 1 and 2, the evaluation device 11 includes a measurement sensor 14 and an acquisition unit 15 that acquires information obtained from the measurement sensor 14 (information related to acceleration).

[0016] The measurement sensor 14 is inserted into the test ready mixed concrete 12 to evaluate the degree of fluidity thereof. The test ready mixed concrete 12 is poured into a formwork 13 to a predetermined height.

[0017] The acquisition unit 15 is configured with a general PC (personal computer) such as a notebook computer. The acquisition unit 15 has a CPU, ROM, RAM, a hard disk, an SSD, and a display unit 15A (display). In addition, as will be described later, software is installed in the acquisition unit 15 that can calculate a resultant acceleration or the like obtained by combining the acceleration in the X-axis direction and the acceleration in the Y-axis direction obtained by the sensor unit 17, and display the calculated resultant acceleration or the like as a graph on the display unit 15A.

[0018] The software can calculate the resultant acceleration using the following formula (1). Resultant acceleration = (1st acceleration2 +2nd acceleration 2 ) 1 / 2 Formula (1) Furthermore, the software can easily determine the inclination of line segment 27 connecting plummet section 21 and float section 22 with respect to the vertical direction using the following equation (2). Slope = asin(resultant acceleration) Equation (2)

[0019] As shown in Fig. 1, the measurement sensor 14 is placed at a position, for example, 200 mm from the vibrator 16. Also, as shown in Fig. 2, the measurement sensor 14 is placed at a depth, for example, 200 mm from the surface (top surface) of the test ready-mix concrete 12 that has been poured into the formwork 13 and will now be fluidized and compacted.

[0020] As shown in FIGS. 3 and 4 , measurement sensor 14 includes weight 21 provided near one end (upper end) of the sensor, float 22 provided near the other end (lower end) opposite the one end, housing 23 connecting weight 21 and float 22, sensor 17 provided within housing 23, connector 24 connected to weight 21, umbrella 25 fixed to connector 24, and cable 26 electrically connecting sensor 17 and acquisition unit 15. Housing 23 and float 22 are fixed by fixing unit 31 (bolt). Cable 26 is an example of an extraction jig. Note that cable 26 can be omitted by wirelessly connecting sensor 17 and acquisition unit 15. In this case, the extraction jig may be formed of a rod having a magnet at its tip. Measurement sensor 14 may also include a metal part (e.g., umbrella 25) that is attached to a magnet. The extraction jig configured in this manner can retrieve the measurement sensor 14 in the test ready-mix concrete 12 by the magnetic force of the magnet.

[0021] Weight portion 21 is cylindrical and made of a metal material, such as stainless steel. Float portion 22 is hollow and made of a synthetic resin material, for example. Air is stored inside float portion 22. The density of float portion 22 is extremely small compared to the density of weight portion 21.

[0022] The housing 23 is formed, for example, from a synthetic resin material into a hollow cylindrical shape. The sensor unit 17 can be housed inside the housing 23. The connecting fitting 24 is formed, for example, from a metal material, such as stainless steel, into a cylindrical shape. The umbrella portion 25 is formed, for example, from a synthetic resin material into a hollow, arched cross section (bullet shape).

[0023] The connector fittings 24 and the cable portion 26 have sufficient strength to withstand the tensile load that is applied when the measurement sensor 14 is removed from the fresh concrete 12 during the third preliminary step described below. The cable portion 26 includes a plurality of electric wires made of a metal material and a sleeve-shaped covering layer that covers the outside of the electric wires. The covering layer of the cable portion 26 is fixed to the connector fittings 24, for example.

[0024] Sensor unit 17 is capable of sensing changes in the tilt of line segment 27 connecting weight portion 21 and float portion 22 relative to the vertical direction. Sensor unit 17 is configured as an acceleration sensor, and in particular, is configured as an acceleration sensor having at least one detection direction axis in a direction perpendicular to line segment 27 connecting weight portion 21 and float portion 22. This sensor unit 17 (acceleration sensor) has detection direction axes in two axial directions perpendicular to line segment 27 connecting weight portion 21 and float portion 22. Sensor unit 17 can sense changes in the tilt of line segment 27 relative to the vertical direction (tilt information) by acquiring acceleration in the two axial directions.

[0025] That is, as shown in FIG. 5, when measurement sensor 14 is in first posture P1 in which float section 22 is located below weight section 21, the direction of line segment 27 connecting the weight section and float section substantially coincides with vertical direction G. In this case, the direction of line segment 27 connecting the weight section and float section is defined as the Z axis, and the directions perpendicular to this Z axis are defined as the X axis and Y axis. The Y axis is perpendicular to the X axis. The acceleration sensor of this embodiment has detection direction axes in the X axis direction and Y axis direction, respectively (first detection direction axis: X axis direction, second detection direction axis: Y axis direction). Furthermore, when in first posture P1, the Z axis substantially coincides with vertical direction G.

[0026] The acquisition unit 15 can calculate a resultant acceleration (gradient) obtained by combining an acceleration (first acceleration) detected in the X-axis direction, which is the first detection direction axis, and an acceleration (second acceleration) detected in the Y-axis direction, which is the second detection direction axis, both of which are acquired from the sensor unit 17. The acquisition unit 15 can also output this resultant acceleration as a graph on the display unit 15A.

[0027] Next, a method for fluidizing ready-mixed concrete using the evaluation device 11 of this embodiment will be described with reference to FIGS.

[0028] The method for fluidizing ready-mixed concrete of the present invention comprises: A method for fluidizing ready-mixed concrete using an evaluation device (11) having a measurement sensor (14) including a weight (21), a float (22) acting on which a buoyancy greater than that of the weight (21) acts, and a sensor unit (17) characterized by detecting a change in inclination of a line segment connecting the weight (21) and the float (22) with respect to the vertical direction, and an acquisition unit that acquires the change in inclination, a measuring step of measuring the rebound degree at a plurality of points on a plurality of hardened test concretes 31 that have been vibrated by a vibrator 16 for different vibration times before hardening; A calculation step of calculating a standard deviation for each of the plurality of hardened test concretes 31 having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes 31 having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete 31 that minimizes the standard deviation; a first preliminary step of placing the measurement sensor 14 in the test ready-mixed concrete 12 in a first position P1 in which the float portion 22 is positioned below the weight portion 21, and inserting the vibrator 16 near the measurement sensor 14; a second preliminary step of operating the vibrator 16 to vibrate the test ready-mixed concrete 12 and fluidizing the test ready-mixed concrete 12, and as the test ready-mixed concrete 12 fluidizes, while the measurement sensor 14 moves from the first position P1 to the second position P2 in which the float portion 22 is positioned above the weight portion 21, or while the measurement sensor 14 is partway from the first position P1 to the second position P2, acquiring first tilt information corresponding to the first position P1 and second tilt information corresponding to after the standard vibration time has elapsed, by the acquiring unit 15; a vibration step of introducing a vibrator 16 into the poured ready-mixed concrete to vibrate it for the standard vibration time; Equipped with In the vibration process, the measurement sensor 14 is placed in the poured fresh concrete in a first position P1, and vibration is applied by the vibrator 16 for the standard vibration time until the tilt change obtained by the acquisition unit 15 changes from the first tilt information to the second tilt information.

[0029] Furthermore, in this embodiment, it is also possible to fluidize the ready-mixed concrete by time management of the standard vibration time without using the evaluation device 11.

[0030] That is, the method for fluidizing ready-mixed concrete of the present invention comprises the steps of: a measuring step of measuring the rebound degree at a plurality of points on a plurality of hardened test concretes 31 that have been vibrated by a vibrator 16 for different vibration times before hardening; A calculation step of calculating a standard deviation for each of the plurality of hardened test concretes 31 having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes 31 having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete 31 that minimizes the standard deviation; a vibration step of introducing a vibrator 16 into the poured ready-mixed concrete to vibrate it for the standard vibration time; Equipped with.

[0031] Multiple hardened test concretes 31 with different vibration times for the measurement process are prepared as follows. As shown in FIG. 6, ready-mixed concrete is poured into a rectangular formwork (1190 mm wide x 590 mm deep x 600 mm high) when viewed from above. In the present invention, eight hardened test concretes 31 with different vibration times are prepared. As shown in FIG. 2, an operator inserts a vibrator 100 mm wide and 100 mm deep from the corner of the formwork. Eight hardened test concretes 31 with different vibration times are then prepared, respectively, for 2-3 seconds, 5 seconds, 10 seconds, 15 seconds, 20 seconds, 30 seconds, 40 seconds, and 50 seconds. After hardening, the ready-mixed concrete is cured in air. In the measurement process, the rebound degree of the side surfaces of the hardened test concrete 31 is measured seven days after pouring the ready-mixed concrete. The surfaces for this rebound degree measurement are the first side surface 31A and the second side surface 31B, which are adjacent to the vibrator insertion point in FIG. 7.

[0032] In the measurement process, as shown in Figures 8 and 9, on each of the first side surface 31A and the second side surface 31B, the degree of rebound is measured using a Schmidt hammer test at the intersections (grid points) of 13 line segments at different positions in the vertical direction and 9 line segments at different positions in the horizontal direction. The pitch of each measurement point is 30 mm in the vertical direction and 30 mm in the horizontal direction. Measurement positions in the horizontal direction are nine points measured at 30 mm intervals, starting from a position overlapping with the vibrator and moving away from the vibrator. Measurement positions in the vertical direction are 13 points measured at 30 mm intervals in the vertical direction from the top surface of the hardened test concrete 31.

[0033] Points where measurement is difficult due to the influence of air bubbles are assigned a value of zero. The number of measurement points on each side is 13 x 9 = 117, for a total of 234 for the first side 31A and the second side 31B. In accordance with the guidelines of the Japan Society of Civil Engineers, values ​​that exceed the mean value ±20% of all data are considered abnormal and are excluded.

[0034] From the obtained data, values ​​at nine points in the horizontal direction are averaged. Therefore, in the present invention, for each hardened test concrete 31 subjected to different vibration times, 13 average values ​​at different measurement heights are obtained from the first side surface 31A and the second side surface 31B, respectively. Some of the average results are shown in Figs. 10 to 12. In Fig. 10, the vibration time by the vibrator 16 is 2 to 3 seconds, in Fig. 11, the vibration time by the vibrator 16 is 20 seconds, and in Fig. 12, the vibration time by the vibrator 16 is 50 seconds. Regression lines are shown in Figs. 10 to 12.

[0035] Figure 13 shows a graph of the absolute value of the slope of the regression line obtained in Figures 10 to 12 in relation to the vibration time. It can be seen that the absolute value of the slope of the regression line increases as the vibration time increases. This is thought to be because vibration causes air bubbles to rise and aggregates in the fresh concrete to sink, resulting in vertical variations in the state of the materials in the fresh concrete. Therefore, it can be seen that unnecessarily lengthening the vibration time is undesirable for obtaining hardened concrete with uniform repulsive force, as it causes uneven distribution of materials in the fresh concrete.

[0036] In the calculation step, a standard deviation is calculated for each of the hardened test concretes 31 with different vibration times from the multiple measurement results of the rebound degree measured for each of the hardened test concretes 31 with different vibration times. At this time, a standard deviation is calculated for the measurement results of the first side 31A of the hardened test concrete 31, and a standard deviation is calculated for the measurement results of the second side 31B of the hardened test concrete 31. In other words, two standard deviations are obtained for each of the hardened test concretes with different vibration times. The calculated standard deviations are shown as a graph in FIG. 14.

[0037] In the selection process, the operator selects the hardened test concrete 31 with the vibration time that provides the smallest average value of the standard deviations obtained from the first side 31A and the second side 31B from the standard deviation graph shown in FIG. 14. For example, in FIG. 14, the hardened test concrete 31 with a vibration time of 20 seconds has the smallest average standard deviation. Therefore, in FIG. 14, the operator selects 20 seconds, which is the vibration time of the selected hardened test concrete 31, as the standard vibration time. Note that, depending on the type of test concrete, a time other than 20 seconds may be selected as the standard vibration time. In other words, the standard vibration time is preferably 15 seconds or more and 30 seconds or less. If the standard vibration time is shorter than 15 seconds, the average value of the standard deviation of the rebound degree increases, as is clear from FIG. 14, and a uniform rebound degree cannot be obtained in the hardened test concrete 31. If the standard vibration time is increased beyond 30 seconds, the absolute value of the slope of the regression line increases, as is clear from Figure 13, and there is a problem that the degree of rebound becomes non-uniform across the vertical height (measurement height) of the hardened test concrete 31.

[0038] The following first to third preliminary steps can be carried out as a preliminary step, and are not necessary if the fluidization and compaction of the ready-mixed concrete are carried out under time management using the standard vibration time described above.

[0039] In the first preliminary step, as shown in Figures 1 and 2, a measurement sensor 14 is inserted near a vibrator 16 that fluidizes the test ready-mix concrete 12. Details of the test ready-mix concrete 12 used here will be described later, but it has the same composition as the hardened test concrete 31 described above.

[0040] In the first preliminary step, the measurement sensor 14 is placed in the test ready-mixed concrete 12 at a position 150 to 250 mm, preferably 170 to 230 mm, and more preferably 190 to 210 mm, from the vibrator 16. In this embodiment, it is most preferable to place the measurement sensor 14 in the test ready-mixed concrete 12 at a position, for example, 200 mm from the vibrator. If the measurement sensor 14 is placed at a position, for example, 150 mm or less from the vibrator 16, there is a possibility that the measurement sensor 14 will be caught up in the vibration of the vibrator 16. On the other hand, if the measurement sensor 14 is placed at a position, for example, 250 mm or more from the vibrator 16, it will be in an area that is less susceptible to the effects of the vibrations from the vibrator 16.

[0041] The measurement sensor 14 is positioned 150 to 250 mm, preferably 170 to 230 mm, and more preferably 190 to 210 mm, from the top surface of the upper layer 12B of the test ready-mixed concrete 12, which is poured above the lower layer 12A of the ready-mixed concrete 12 that has already been poured and compacted the first time. In this embodiment, it is most preferable to place the measurement sensor 14 at a position, for example, 200 mm from the top surface of the upper layer 12B of the test ready-mixed concrete 12 that has been poured in the upper layer. The measurement sensor 14 can also be used to evaluate the test ready-mixed concrete 12A poured the first time and test ready-mixed concrete poured the third time or later. The measurement sensor 14 is positioned at the above-mentioned predetermined position by, for example, a worker using a rod or by an operator of a device equipped with a rod tool. The height of the lower layer of ready-mixed concrete 12A that has already been compacted is, for example, 50 cm. In the first preliminary step, the measurement sensor 14 is placed in the test ready mixed concrete 12B in a first posture P1 in which the float portion 22 is positioned below the weight portion 21.

[0042] The test ready-mix concrete 12 is a general ready-mix concrete in which each material is commercially available.

[0043] The slump value of the test ready mixed concrete 12 is 1 to 25 cm, may be 4 to 20 cm, may be 5 to 16 cm, or may be 6 to 15.5 cm.

[0044] For example, the mix proportion of the test ready-mixed concrete 12 when the slump value is set to 6 cm is, for example, 18-8-20N.

[0045] For example, when the slump value is set to 15.5 cm, the mix proportion of the test ready-mixed concrete 12 is, for example, 18-15-20N.

[0046] The vibrator 16 is a typical vibrator used to compact the test ready-mixed concrete 12. The vibrator 16 penetrates the upper layer to be compacted, and about 100 mm of its tip is inserted into the already compacted lower layer. If the test ready-mixed concrete 12 to be evaluated is the first pour of ready-mixed concrete, it is necessary to ensure that the vibrator 16 does not come into contact with the bottom. Depending on the diameter and vibration output strength, if the vibrator 16 has a diameter of 50 mm, the vibrations will be transmitted within an area with a radius of, for example, about 250 mm from the center of the vibrator 16, and the ready-mixed concrete 12 can be compacted.

[0047] In the second preliminary step, the vibrator 16 is operated with the measurement sensor 14 positioned in the test ready-mixed concrete 12B in the above-described positional relationship. This fluidizes and compacts the test ready-mixed concrete 12B. The time for which the vibrator 16 vibrates the test ready-mixed concrete 12B is the standard vibration time (20 seconds in this embodiment). When the vibrator 16 is operated, the particles that make up the test ready-mixed concrete 12B tend to fall into the gaps between the particles due to the vibration. This increases the water pressure in the gaps. This reduces the frictional force between the particles, and buoyancy becomes dominant over frictional force in the test ready-mixed concrete 12B. This causes the test ready-mixed concrete 12B to fluidize.

[0048] As fluidization progresses in the test ready-mixed concrete 12B, the frictional force around the measurement sensor 14 decreases. Then, in the second step, the buoyancy acting on the float portion 22 causes the measurement sensor, which is in the first position P1, to gradually rotate so that the float portion 22 faces upward (as if upside down). As a result, the measurement sensor 14 attempts to change from the first position P1 to the second position P2 in which the float portion 22 is positioned above the weight portion 21.

[0049] Sensor unit 17 of measurement sensor 14 can detect changes in the inclination of line segment 27 connecting weight portion 21 and float portion 22 relative to the vertical direction. Sensor unit 17 is composed of an acceleration sensor. Sensor unit 17 is an acceleration sensor that has at least one detection direction axis in a direction perpendicular to line segment 27 connecting weight portion 21 and float portion 22.

[0050] In the second preliminary step, the acquisition unit 15 acquires changes in tilt information associated with changes in the attitude of the measurement sensor 14 from the start of vibration of the vibrator 16 until the standard vibration time has elapsed. That is, the acquisition unit 15 acquires first tilt information corresponding to the first attitude P1 and second tilt information corresponding to after the standard vibration time has elapsed while the measurement sensor 14 moves from the first attitude P1 to the second attitude P2 in which the float portion 22 is positioned above the weight portion 21, or while the measurement sensor 14 is moving from the first attitude P1 to the second attitude P2. The first tilt information and the second tilt information are acquired appropriately, for example, from tilt information of the measurement sensor 14 continuously acquired by the acquisition unit 15.

[0051] When the line segment 27 connecting the weight portion 21 and the float portion 22 is positioned along the vertical direction (when in the first attitude P1), the resultant acceleration (resultant acceleration in the X and Y axis directions) calculated by the acquisition unit 15 takes a value close to 0G.

[0052] As the ready-mixed concrete 12 becomes fluid, the measurement sensor 14 rotates and assumes an intermediate position P0 between the first position P1 and the second position P2. At this time, the line segment 27 connecting the weight portion 21 and the float portion 22 is positioned along a substantially horizontal plane. At this time, the resultant acceleration sensed by the sensor portion 17, which is a combination of the acceleration detected in the X-axis direction and the acceleration detected in the Y-axis direction, is on the same axis as the acceleration of gravity and has a peak value near 1 G.

[0053] In the second preliminary step, if the operation of the vibrator 16 continues, the degree of fluidization of the fresh concrete 12 will further progress, and as shown in Figure 5, the measurement sensor 14 will rotate from the intermediate position P0 to the second position P2.

[0054] The ready-mixed concrete fluidization method of the present invention includes a third preliminary step of retrieving the measurement sensor 14 from the test ready-mixed concrete 12 after the second preliminary step is completed. The measurement sensor 14 is connected to, for example, a removal jig (cable portion 26 in this embodiment), and at least a portion of the removal jig is located outside the ready-mixed concrete 12. In the third preliminary step, the measurement sensor 14 is retrieved from the ready-mixed concrete 12 by removing the removal jig.

[0055] In the vibration process, the vibrator 16 and measurement sensor 15 are introduced into the poured ready-mixed concrete and vibrate it for the standard vibration time. At this time, the positional relationship between the vibrator 16 and the measurement sensor 15 is the same as in the first preliminary process. This vibration process is carried out until the tilt information of the measurement sensor 14 changes from the first tilt information to the second tilt information. At this time, the worker visually checks the acquisition unit 15 and continues vibration by the vibrator 16 until the tilt of the measurement sensor 14 changes from the first tilt information to the second tilt information. When the tilt of the measurement sensor 14 reaches the second tilt information, the vibrator 16 is removed, as it is determined that the fluidization of the ready-mixed concrete has been completed.

[0056] The vibration process involves injecting the vibrator 16 and measurement sensor 14 into the poured ready-mixed concrete at a specified pitch, and repeating the above process until the poured ready-mixed concrete is uniformly fluidized throughout. In this way, by fluidizing the ready-mixed concrete using changes in the slope information obtained by the measurement sensor 14 rather than simply managing the standard vibration time, it is possible to always fluidize the ready-mixed concrete to the same degree, even if the quality and properties of the ready-mixed concrete vary from site to site.

[0057] On the other hand, in the vibration step, the worker may simply measure the standard vibration time and remove the vibrator 16 after the standard vibration time has elapsed, thereby fluidizing and compacting the ready-mixed concrete.

[0058] According to this embodiment, the following can be said: The method for fluidizing ready-mixed concrete uses an evaluation device 11 having a measurement sensor 14 including a weight 21, a float 22 that exerts a buoyancy greater than that of the weight 21, and a sensor unit 17 that detects a change in inclination of a line segment 27 connecting the weight 21 and the float 22 with respect to the vertical direction G, and an acquisition unit 15 that acquires the change in inclination. The method for fluidizing ready-mixed concrete includes a measuring step of measuring the degree of rebound at a plurality of locations on a plurality of hardened test concretes 31 that have been vibrated by a vibrator 16 for different vibration times before hardening; a calculating step of calculating a standard deviation for each of the plurality of hardened test concretes 31 that have different vibration times from a plurality of measurement results of the degree of rebound measured for each of the plurality of hardened test concretes 31 that have different vibration times; a selecting step of selecting the vibration time for the hardened test concrete 31 that minimizes the standard deviation as the standard vibration time; a first preliminary step of installing a measurement sensor 14 in the test ready-mixed concrete 31 in a first position P1 in which the float part 22 is located below the weight part 21 and inserting a vibrator 16 near the measurement sensor 14; and a test step of operating the vibrator 16 to vibrate the test ready-mixed concrete 31. The method includes a second preliminary step in which the measurement sensor 14 is moved from the first position P1 to the second position P2 in which the float portion 22 is positioned above the weight portion 21 as the test ready-mixed concrete 12 is fluidized, or while the measurement sensor 14 is moving from the first position P1 to the second position P2 in which the float portion 22 is positioned above the weight portion 21, and the acquisition unit 15 acquires first tilt information corresponding to the first position P1 and second tilt information corresponding to after the standard vibration time has elapsed, and a vibration step in which a vibrator 16 is introduced into the poured ready-mixed concrete to vibrate it for the standard vibration time, in which the measurement sensor 14 is placed in the poured ready-mixed concrete at the first position P1, and the vibrator 16 applies vibration for the standard vibration time until the tilt change obtained by the acquisition unit 15 changes from the first tilt information to the second tilt information.

[0059] According to this configuration, since the vibration for the standard vibration time is determined based on the change in slope from the first slope information to the second slope information, the degree of fluidity of poured fresh concrete can be made uniform even if the quality of the poured fresh concrete varies slightly from site to site. Furthermore, even if the hardness and properties of the poured fresh concrete vary depending on the season or weather, the degree of fluidity of the poured fresh concrete can be made uniform. Furthermore, the degree of fluidity of the poured fresh concrete can be made uniform even in areas that are difficult for workers to see due to the structure.

[0060] Another method for fluidizing ready-mixed concrete includes a measurement step of measuring the degree of rebound at multiple locations on multiple hardened test concretes 31 that have been vibrated by a vibrator 16 for different vibration times before hardening; a calculation step of calculating a standard deviation for each of multiple hardened test concretes 31 with different vibration times from multiple measurement results of the degree of rebound measured for each of the multiple hardened test concretes 31 with different vibration times; a selection step of selecting the vibration time of the hardened test concrete 31 that minimizes the standard deviation as the standard vibration time; and a vibration step of introducing a vibrator 16 into the poured ready-mixed concrete to vibrate it for the standard vibration time.

[0061] This configuration eliminates the need for measurement sensors, etc. As a result, by setting the vibration time with the smallest standard deviation of the rebound rate as the standard vibration time, it is possible to construct hardened concrete with a fairly small variation in the rebound rate with an extremely simple configuration. This makes it possible to easily construct good concrete with a small variation in the rebound rate.

[0062] The above embodiment is merely an example, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0063] 11 Evaluation equipment 12 Ready-mix concrete 14 Measurement Sensor 15 Acquisition Department 16 Vibrator 17 Sensor section 21 Weight 22 Float section 23 Case 25 Umbrella section 26 Cable section 27 line segments 31 Hardened test concrete P1 1st posture P0 intermediate posture P2 2nd posture

Claims

1. A method for fluidizing ready-mixed concrete using an evaluation device having a measurement sensor including a weight portion, a float portion on which a buoyancy greater than that of the weight portion acts, and a sensor portion characterized by detecting a change in inclination of a line segment connecting the weight portion and the float portion relative to a vertical direction, and an acquisition portion that acquires the change in inclination, a measuring step of measuring the rebound degree at a plurality of points of a plurality of hardened test concretes which have been vibrated by a vibrator for different vibration times before hardening; a calculation step of calculating a standard deviation for each of the plurality of hardened test concretes having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete that minimizes the standard deviation; a first preliminary step of installing the measurement sensor in a first posture in which the float portion is positioned lower than the weight portion in the test ready-mixed concrete, and inserting the vibrator near the measurement sensor; a second preliminary step of operating the vibrator to vibrate the test ready-mixed concrete to fluidize the test ready-mixed concrete, and acquiring, with the acquisition unit, first tilt information corresponding to the first position and second tilt information corresponding to after the standard vibration time has elapsed while the measurement sensor moves from the first position to a second position in which the float portion is positioned above the weight portion as the test ready-mixed concrete fluidizes, or while the measurement sensor is midway from the first position to the second position; a vibration step of introducing a vibrator into the poured fresh concrete to vibrate it for the standard vibration time; Equipped with In the vibration step, the measurement sensor is placed in the poured fresh concrete in the first position, and vibration by the vibrator for the standard vibration time is performed until the inclination change obtained by the acquisition unit changes from the first inclination information to the second inclination information.

2. a measuring step of measuring the rebound degree at a plurality of points of a plurality of hardened test concretes which have been vibrated by a vibrator for different vibration times before hardening; a calculation step of calculating a standard deviation for each of the plurality of hardened test concretes having different vibration times from a plurality of measurement results of the rebound degree measured for each of the plurality of hardened test concretes having different vibration times; a selection step of selecting, as a standard vibration time, the vibration time of the hardened test concrete that minimizes the standard deviation; a vibration step of introducing a vibrator into the poured fresh concrete to vibrate it for the standard vibration time; A method for fluidizing ready-mixed concrete comprising:

Images