Method for evaluating the degree of fluidity of ready-mixed concrete, measurement sensor, and device for evaluating the degree of fluidity of ready-mixed concrete

Abstract

To provide an evaluation method of fluidity degree of ready-mixed concrete, a measurement sensor, and an evaluation device of fluidity degree of ready-mixed concrete which can evaluate fluidity degree of concrete extremely simply and in real time.SOLUTION: An evaluation method of fluidity degree of ready-mixed concrete comprises: a first step and a second step. In the first step, a measurement sensor is placed in the vicinity of a vibrator in a first posture in which a float portion is located below a weight portion in ready-mixed concrete. In the second step, the vibrator is operated to fluidize the fresh concrete. As the ready-mixed concrete is fluidized, an evaluation portion acquires an inclination from the measurement sensor while the measurement sensor moves from the first posture to a second posture in which the float portion is located above the weight portion or while the measurement sensor is halfway from the first posture to the second posture, and a fluidity degree of the ready-mixed concrete is evaluated based on a change in the inclination.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the degree of fluidity of concrete, a measurement sensor, and an evaluation device for evaluating the degree of fluidity of 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] However, in the method for determining the completion of concrete compaction in Patent Document 1, the floaters are placed at a pitch of 50 cm, which means that at least 19 floaters are required for a 10 m wide structure, resulting in a 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] Therefore, an object of the present invention is to provide a method for evaluating the fluidity degree of ready-mixed concrete, a measurement sensor, and an apparatus for evaluating the fluidity degree of ready-mixed concrete, which can evaluate the fluidity degree of concrete extremely simply and in real time. [Means for solving the problem]

[0010] The above-mentioned problems are solved by the present invention. That is, the method for evaluating the fluidity degree of ready-mixed concrete according to the present invention (1) comprises: A method for evaluating the fluidity of ready-mixed concrete using an evaluation device having a measurement sensor including a weight portion, a float portion acting on the weight portion with a buoyancy greater than that of the weight portion, and a sensor portion that detects a change in inclination of a line segment connecting the weight portion and the float portion relative to a vertical direction, and an evaluation portion that acquires the change in inclination and evaluates the fluidity of the ready-mixed concrete, a first step of installing the measurement sensor in a first posture in which the float portion is positioned lower than the weight portion in the fresh concrete, and inserting an activated or unactivated vibrator near the measurement sensor; a second step of operating the vibrator to vibrate the fresh concrete and fluidize the fresh concrete, and as the fresh concrete fluidizes, acquiring the change in inclination from the measurement sensor with the evaluation unit 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, and evaluating the degree of fluidization of the fresh concrete based on time-series data of the change in inclination; Equipped with.

[0011] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (2) is the method for evaluating the fluidity degree of ready-mixed concrete according to (1), The method includes a third step of recovering the measurement sensor from the fresh concrete after the second step has started.

[0012] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (3) is the method for evaluating the fluidity degree of ready-mixed concrete according to (2), The measurement sensor is connected to an extraction jig, and at least a portion of the extraction jig is located outside the fresh concrete. In the third step, the extraction jig is extracted to recover the measurement sensor from the fresh concrete.

[0013] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (4) is a method for evaluating the fluidity degree of ready-mixed concrete according to any one of (1) to (3), In the second step, the evaluation unit plots a graph of the change in slope and determines the completion of compaction from the time-series data of the graph.

[0014] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (5) is a method for evaluating the fluidity degree of ready-mixed concrete according to any one of (1) to (3), In the second step, the evaluation unit plots a graph of the change in slope and predicts the vibration time until compaction is completed from the time series data of the graph.

[0015] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (6) is the method for evaluating the fluidity degree of ready-mixed concrete according to (5), The vibration time until compaction is completed is determined by determining a point within a specified range of the graph of the slope change and the average slope of the graph at that point, and the time until an extension line with the slope extended from that point reaches a predetermined slope change that determines that compaction is complete.

[0016] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (7) is the method for evaluating the fluidity degree of ready-mixed concrete according to (2) or (3), The third step is performed before the completion of the compaction, and the vibration of the fresh concrete by the vibrator is performed until the time of the completion of the compaction.

[0017] Further, the method for evaluating the fluidity degree of ready-mixed concrete of the present invention (8) is a method for evaluating the fluidity degree of ready-mixed concrete according to any one of (1) to (3), The sensor unit has a first detection axis and a second detection axis that are respectively perpendicular to a direction perpendicular to a line segment connecting the weight unit and the float unit, and detects a first acceleration and a second acceleration on the first detection axis and the second detection axis, and calculates a resultant acceleration by the following formula: Resultant acceleration = (1st acceleration 2 +2nd acceleration 2 ) 1 / 2 The gradient of the resultant acceleration is calculated using the following formula: Slope = asin(resultant acceleration).

[0018] Further, the measurement sensor of the present invention (9) is a measurement sensor for measuring the fluidity degree of the fresh concrete, which is inserted into the fresh concrete, A weight portion, a float portion on which a buoyancy greater than that of the weight portion acts; a sensor unit that detects a change in the inclination of a line segment connecting the weight unit and the float unit with respect to a vertical direction; Equipped with.

[0019] Further, the measurement sensor of the present invention (10) is the measurement sensor according to (9), The sensor unit detects acceleration, and detects the change in tilt from the change in acceleration.

[0020] Further, the measurement sensor of the present invention (11) is the measurement sensor according to (9) or (10), The sensor portion has at least one detection axis in a direction perpendicular to a line segment connecting the weight portion and the float portion.

[0021] Further, the measurement sensor of the present invention (12) is the measurement sensor according to (9) or (10), The sensor portion has a detection axis in a direction parallel to a line segment connecting the weight portion and the float portion.

[0022] Further, the measurement sensor of the present invention (13) is the measurement sensor according to (9) or (10), The sensor unit has a capacitor, operates on power supplied from the capacitor, and is characterized in that the capacitor is located on the side of the weight unit on a line segment connecting the weight unit and the float unit.

[0023] Further, the measurement sensor of the present invention (14) is the measurement sensor according to (13), The capacitor is characterized by being the weight portion.

[0024] Further, the measurement sensor of the present invention (15) is the measurement sensor according to (9) or (10), The measurement sensor has an umbrella portion, the umbrella portion is located outside the weight portion on a line segment connecting the weight portion and the float portion, The umbrella portion has an arch-shaped cross section that is convex in a direction away from the weight portion.

[0025] In addition, the evaluation device for the degree of fluidity of ready-mixed concrete of the present invention (16) is An apparatus for evaluating the degree of fluidity of ready-mixed concrete, the apparatus having a measurement sensor and an evaluation unit, the measurement sensor having a weight unit, a float unit, and a sensor unit, the sensor unit detects a change in inclination of a line segment connecting the weight unit and the float unit with respect to a vertical direction, The evaluation unit receives the change in inclination detected by the sensor unit due to the rotation of the measurement sensor when the measurement sensor is embedded in the fresh concrete, and evaluates the degree of fluidity of the fresh concrete from the change in inclination.

[0026] The apparatus for evaluating the fluidity degree of ready-mixed concrete according to the present invention (17) is the apparatus for evaluating the fluidity degree of ready-mixed concrete according to the present invention (16), The evaluation unit is characterized in that it determines the completion of compaction of the ready-mixed concrete from the time-series data of the slope change.

[0027] The apparatus for evaluating the fluidity degree of ready-mixed concrete according to the present invention (18) is the apparatus for evaluating the fluidity degree of ready-mixed concrete according to the present invention (16), The evaluation unit is characterized in that it predicts the vibration time until the compaction of the fresh concrete is completed from the time series data of the slope change. [Effects of the Invention]

[0028] According to the present invention, it is possible to provide a method for evaluating the fluidity degree of ready-mixed concrete and an apparatus for evaluating the fluidity degree of ready-mixed concrete, which can evaluate the fluidity degree of concrete extremely simply and in real time. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram showing an evaluation device for evaluating the fluidity degree of ready-mixed concrete according to a first embodiment. FIG. [Figure 2] 2 is a cross-sectional view showing a state in which a measurement sensor of the device for evaluating the fluidity degree of ready-mixed concrete shown in FIG. 1 is installed in 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] 5 is a graph showing the degree of fluidity of ready-mixed concrete measured by a method for evaluating the degree of fluidity of ready-mixed concrete using the device for evaluating the degree of fluidity of ready-mixed concrete shown in FIGS. 1 to 4. [Figure 7] This graph explains that in the graph shown in Figure 6, the time it takes for an extension line with the average gradient of the graph at one point to reach a predetermined resultant acceleration that is predicted as compaction completion is the vibration time that is predicted as compaction completion. [Figure 8] FIG. 10 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a first modified example. [Figure 9] FIG. 10 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a second modified example. [Figure 10] FIG. 11 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a third modified example. [Figure 11] FIG. 11 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a fourth modified example. [Figure 12] FIG. 11 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a fifth modified example. [Figure 13] FIG. 13 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a sixth modified example. [Figure 14] FIG. 13 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a seventh modified example. [Figure 15] FIG. 13 is a cross-sectional view taken along the central axis direction of a measurement sensor according to an eighth modified example. [Figure 16] FIG. 13 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a ninth modified example. [Figure 17] FIG. 23 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a tenth modified example. [Figure 18]FIG. 20 is a cross-sectional view taken along the central axis direction of a measurement sensor according to an eleventh modified example. [Figure 19] FIG. 23 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a twelfth modified example. [Figure 20] FIG. 23 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a thirteenth modified example. [Figure 21] FIG. 23 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a fourteenth modified example. [Figure 22] FIG. 23 is a cross-sectional view taken along the central axis direction of a measurement sensor according to a fifteenth modified example. [Figure 23] 10 is a graph showing the degree of fluidity of ready-mixed concrete measured using a method for evaluating the degree of fluidity of ready-mixed concrete using an evaluation device according to a second embodiment. [Figure 24] This graph explains that in the graph shown in Figure 23, the time it takes for an extension line with the average gradient of the graph at one point to reach a preset acceleration predicted as compaction completion is the vibration time predicted as compaction completion. [Figure 25] This is a graph that explains that in a form that combines the first and second embodiments, the time until an extension line with the average gradient of the graph at one point reaches a predetermined acceleration that is predicted as compaction completion is taken as the vibration time that is predicted as compaction completion. DETAILED DESCRIPTION OF THE INVENTION

[0030] The method for evaluating the fluidity degree of ready-mixed concrete of the present invention includes: A method for evaluating the fluidity of ready-mixed concrete using an evaluation device having a measurement sensor including a weight portion, a float portion acting on the weight portion with a buoyancy greater than that of the weight portion, and a sensor portion that detects a change in inclination of a line segment connecting the weight portion and the float portion relative to a vertical direction, and an evaluation portion that acquires the change in inclination and evaluates the fluidity of the ready-mixed concrete, a first step of installing the measurement sensor in a first posture in which the float portion is positioned lower than the weight portion in the fresh concrete, and inserting an activated or unactivated vibrator near the measurement sensor; a second step of operating the vibrator to vibrate the fresh concrete and fluidize the fresh concrete, and as the fresh concrete fluidizes, acquiring the change in inclination from the measurement sensor with the evaluation unit 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, and evaluating the degree of fluidization of the fresh concrete based on time-series data of the change in inclination; Equipped with.

[0031] In the first step, a vibrator for fluidizing the fresh concrete is inserted near the measurement sensor.

[0032] As shown in Fig. 1, in the first step, the measurement sensor is placed at a position 150 to 250 mm, preferably 170 to 230 mm, and more preferably 190 to 210 mm, from the vibrator. In this embodiment, it is most preferable to place the measurement sensor at a position, for example, 200 mm from the vibrator. If the measurement sensor is placed at a position, for example, 150 mm or less from the vibrator, there is a possibility that the measurement sensor will be caught up in the vibration of the vibrator. On the other hand, if the measurement sensor is placed at a position, for example, 250 mm or more from the vibrator, it will be in an area that is less susceptible to the influence of the vibration from the vibrator.

[0033] As shown in FIG. 2, the measurement sensor 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 of fresh concrete that has already been poured and compacted in the first pour above the lower layer of fresh concrete. In this embodiment, it is most preferable to place the measurement sensor at a position, for example, 200 mm from the top surface of the upper layer of fresh concrete poured in the upper layer. The evaluation device can also be used to evaluate the first pour of fresh concrete or fresh concrete poured in the third or subsequent pours. The measurement sensor is placed at the above-mentioned predetermined position by, for example, a worker using a rod or the like, or by the operator of the device using a device equipped with a rod tool or the like. The height of the compacted fresh concrete in the lower layer is, for example, 50 cm. In the first step, the measurement sensor is installed in the fresh concrete in a first position in which the float portion is positioned below the weight portion.

[0034] The ready-mix concrete is a common ready-mix concrete in which each material is commercially available. The slump value of the ready-mixed concrete 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.

[0035] For example, the mix ratio of ready-mixed concrete when the slump value is 6 cm is 18-8-20N.

[0036] For example, the mix ratio of ready-mixed concrete when the slump value is 15.5 cm is 18-15-20N.

[0037] The vibrator consists of a general vibrator used for compacting ready-mixed concrete. The vibrator penetrates the upper layer to be compacted, and the first 100 mm or so of its tip is inserted into the already compacted lower layer. If the ready-mixed concrete being evaluated is the first pour of ready-mixed concrete, it is necessary to ensure that the vibrator does not come into contact with the bottom. Depending on the diameter and vibration output strength of the vibrator, if the diameter is 50 mm, for example, a range of about a 250 mm radius from the center of the vibrator will be able to transmit vibrations and compact the ready-mixed concrete.

[0038] In the second step, with the measurement sensor positioned in the fresh concrete as described above, the vibrator is activated. This compacts the fresh concrete. When the vibrator is activated, the particles that make up the fresh concrete tend to fall into the gaps between them due to the vibrations. This increases the water pressure in the gaps. This reduces the frictional force between the particles, and buoyancy becomes more dominant than frictional force in the fresh concrete. This causes the fresh concrete to flow.

[0039] As fluidization progresses in the fresh concrete, the frictional force around the measurement sensor decreases. Then, in the second step, the buoyancy acting on the float part causes the measurement sensor, which is in the first position, to gradually rotate so that the float part faces upward (as if upside down). This causes the measurement sensor to change from the first position to the second position, in which the float part is positioned above the weight part.

[0040] The sensor unit can detect changes in the inclination of the line segment connecting the weight unit and the float unit relative to the vertical direction. The sensor unit is an acceleration sensor that has at least one detection direction axis in a direction perpendicular to the line segment connecting the weight unit and the float unit.

[0041] The method for evaluating the fluidity degree of ready-mixed concrete of the present invention includes a third step of retrieving the measurement sensor from the ready-mixed concrete after the start of the second step. The measurement sensor is connected to a removal jig, and at least a portion of the removal jig is located outside the ready-mixed concrete. In the third step, the measurement sensor is retrieved from the ready-mixed concrete by removing the removal jig.

[0042] The third step is carried out before the time when compaction is predicted to be completed. The third step is carried out several seconds to several tens of seconds, preferably 1 to 10 seconds, and more preferably 1 to 5 seconds before the time when compaction is predicted to be completed. On the other hand, the operation of the vibrator in the second step is carried out until the time when compaction is predicted to be completed.

[0043] The vibration time that is predicted to indicate the completion of compaction is set as the time until the extension line of the gradient set between 1 and 10 seconds on the acceleration graph reaches the predetermined resultant acceleration that is predicted to indicate the completion of compaction. The resultant acceleration that is predicted to indicate the completion of compaction is set based on the relationship between the resultant acceleration and the quality of the concrete after hardening.

[0044] Hereinafter, an embodiment of an apparatus for evaluating the fluidity degree of ready-mixed concrete used in the method for evaluating the fluidity degree of ready-mixed concrete of the present invention will be described with reference to the drawings. [First embodiment]

[0045] 1 and 2, a measurement sensor 14 is inserted into the ready-mixed concrete to evaluate the degree of fluidity. Ready-mixed concrete 12 is poured into a formwork 13 to a predetermined height.

[0046] The evaluation device 11 has a measurement sensor 14 and an evaluation unit 15 that acquires and evaluates information (information related to acceleration) obtained from the measurement sensor 14. The evaluation unit 15 is configured as a general PC (personal computer) such as a laptop computer. The evaluation unit 15 has a CPU, ROM, RAM, a hard disk, an SSD, and a display unit 15A (display). In addition, software is installed in the evaluation unit 15 that can calculate a resultant acceleration, etc., by combining the acceleration in the X-axis direction and the acceleration in the Y-axis direction obtained by the sensor unit 17, as described below, and display the calculated resultant acceleration, etc., as a graph on the display unit 15A.

[0047] The software can calculate the resultant acceleration using the following formula (1). Resultant acceleration = (1st acceleration 2 +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)

[0048] 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 of, for example, 200 mm from the surface (top surface) of the ready-mixed concrete 12 that has been poured into the formwork 13 and is about to be compacted.

[0049] As shown in FIGS. 3 and 4 , the measurement sensor 14 includes a weight 21 provided near one end (upper end) of the sensor, a float 22 provided near the other end (lower end) opposite the one end, a housing 23 connecting the weight 21 and the float 22, a sensor 17 provided within the housing 23, a connector 24 connected to the weight 21, an umbrella 25 fixed to the connector 24, and a cable 26 electrically connecting the sensor 17 and the evaluation unit 15. The housing 23 and the float 22 are fixed by a fixing portion 31 (bolt). The cable 26 is an example of an extraction jig. The cable 26 can be omitted by wirelessly connecting the sensor 17 and the evaluation unit 15. In this case, the extraction jig may be formed of a rod having a magnet at its tip. The measurement sensor 14 may also have a metal part (e.g., the umbrella 25) that is attached to a magnet. The extraction jig configured in this manner can retrieve the measurement sensor 14 in the ready-mix concrete 12 by the magnetic force of the magnet.

[0050] 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.

[0051] 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).

[0052] 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 in the third 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.

[0053] 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.

[0054] 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.

[0055] The evaluation 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 evaluation unit 15 can also output this resultant acceleration as a graph on the display unit 15A.

[0056] Next, a method for evaluating the fluidity degree of ready-mixed concrete using the evaluation device 11 for evaluating the fluidity degree of ready-mixed concrete of this embodiment will be described with reference to Figures 1 to 7. In the evaluation method of this embodiment, two types of ready-mixed concrete 12 with different slump values ​​(slump value 6 cm and slump value 15.5 cm) were used. In addition, in the graph of Figure 6, when the line segment 27 connecting the weight portion and the float portion 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 evaluation unit 15 takes a value close to 0 G.

[0057] A worker who wishes to compact the ready-mixed concrete 12 pours the ready-mixed concrete 12 into a formwork 13. The state shown in Figures 1 and 2 shows a state in which an upper layer 12B of ready-mixed concrete 12 to be compacted has been newly poured on top of the lower layer 12A of ready-mixed concrete 12 that has already been poured.

[0058] Generally, a worker operates the vibrator 16 and places it at an appropriate position in the ready-mixed concrete 12. At this time, the tip of the vibrator 16 is inserted into the ready-mixed concrete 12 in the lower layer 12A to a position, for example, about 100 mm.

[0059] In the first step, the vibrator 16 is placed near the measurement sensor 14, i.e., at a position, for example, 200 mm from the measurement sensor 14. The measurement sensor 14 is placed, for example, 200 mm from the surface of the ready-mixed concrete 12 in the upper layer 12B, using a device equipped with an insertion rod or rod tool. At this time, the measurement sensor 14 is placed in a first position P1 in which the float portion 22 is positioned below the weight portion 21.

[0060] In the second step, the vibration of vibrator 16 causes gradual fluidization (compaction) around vibrator 16, particularly within a radius of, for example, about 250 mm from the vibrator if the diameter of vibrator 16 is 50 mm. As the fresh concrete 12 around vibrator 16 gradually fluidizes, the frictional force acting on measurement sensor 14 gradually decreases. Then, as the frictional force acting on measurement sensor 14 decreases, the effect of buoyancy acting on float portion 22 increases, and measurement sensor 14 moves from first position P1 to second position P2 in which float portion 22 is positioned above weight portion 21, as shown in FIG. 5.

[0061] At this time, the evaluation unit 15 calculates a resultant acceleration by combining the acceleration detected in the X-axis direction and the acceleration detected in the Y-axis direction obtained from the sensor unit 17. When the measurement sensor 14 is in the first attitude P1, the Z-axis direction shown in Fig. 5 substantially coincides with the vertical direction G, and therefore the resultant acceleration is almost zero as shown in Fig. 6.

[0062] As the fresh concrete 12 fluidizes, 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, as shown in Figure 6, 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 gravitational acceleration and has a peak value near 1G.

[0063] In the second step, as the operation of the vibrator 16 continues, the degree of fluidization of the ready-mixed concrete 12 further progresses, and as shown in FIG. 5, the measurement sensor 14 rotates from the intermediate position P0 to the second position P2.

[0064] Here, if compaction completion can be evaluated at or near the peak value of the graph (region B shown in FIG. 6 ) based on the physical properties and composition of the fresh concrete and the surrounding environment, the worker removes the measurement sensor 14 when the resultant acceleration reaches or near the peak value (third step). At this time, the worker retrieves the measurement sensor 14 by pulling up the cable portion 26. That is, in this case, in the second step, the evaluation unit 15 acquires the tilt (tilt information: acceleration) from the sensor portion 17 while the measurement sensor 14 is moving from the first position P1 to the second position P2 (intermediate position P0). At this time, the arched umbrella portion 25 reduces the resistance force applied to the measurement sensor 14 during removal, thereby improving the removability of the measurement sensor 14. In this embodiment, the timing to remove the measurement sensor 14 is determined by the worker's own judgment. However, the evaluation unit 15 may also display the remaining time until compaction completion (predicted time of compaction completion) based on the waveform of the graph to prompt the worker to remove the measurement sensor 14.

[0065] After removing the measurement sensor 14, the worker continues to operate the vibrator 16 for several to several tens of seconds to achieve the desired degree of compaction of the ready-mixed concrete 12. In this way, by continuing to operate the vibrator 16 even after removing the measurement sensor 14, the cavity where the measurement sensor 14 was removed can be filled with fluidized ready-mixed concrete 12. This prevents the area where the measurement sensor 14 was removed from becoming a defect.

[0066] On the other hand, if the physical properties and composition of the fresh concrete 12 and the surrounding environment indicate that compaction is complete before the peak of the graph and near the base of the mountain-shaped curve, or after the peak (area A or area C shown in FIG. 6, i.e., a position outside the peak), the worker removes the measurement sensor 14 either before the measurement sensor 14 reaches the second posture P2 (or its vicinity) shown in FIG. 5 (more specifically, before the intermediate posture P0), or when the resultant acceleration passes the peak and begins to decrease significantly, and the measurement sensor 14 reaches the second posture P2 (or its vicinity) shown in FIG. 5 (step 3). At this time, the worker retrieves the measurement sensor 14 by pulling up the cable 26. That is, in this case, the evaluation unit 15 acquires the tilt (tilt information: acceleration) from the sensor unit 17 while the measurement sensor 14 moves from the first posture P1 to the second posture P2. In this embodiment, the timing for removing the measurement sensor 14 is decided by the worker himself, but the evaluation unit 15 may also display the remaining time until compaction is completed (predicted time of compaction completion) based on the waveform of the graph to prompt the worker to remove the measurement sensor 14.

[0067] Alternatively, the evaluation unit 15 may determine any one of points D and E within a predetermined range outside the peak value of the graph. That is, as shown in Fig. 7, the evaluation unit 15 may determine the average gradient of the graph at that point, and use the time until extension lines F and G having the gradient extended from that point reach preset resultant accelerations H and I that are predicted to indicate the completion of compaction as the vibration time predicted to indicate the completion of compaction. Here, the resultant acceleration predicted to indicate the completion of compaction is appropriately set based on the relationship between the resultant acceleration and the quality of the hardened concrete.

[0068] After removing the measurement sensor 14, the worker continues to operate the vibrator 16 for several to several tens of seconds to achieve the desired degree of compaction of the ready-mixed concrete 12. In this case, by continuing to operate the vibrator 16 even after removing the measurement sensor 14, the cavity where the measurement sensor 14 was removed can be filled with fluidized ready-mixed concrete 12. This prevents the area where the measurement sensor 14 was removed from becoming a defect.

[0069] After compaction at this position is complete, the worker inserts the vibrator 16 into the ready-mixed concrete 12 at another position within the formwork 13 and carries out steps 1 to 3. In this way, by moving the vibrator 16 and the measurement sensor 14 sequentially or simultaneously within the formwork 13, all of the ready-mixed concrete 12 within the formwork 13 is made to flow uniformly. This completes the compaction work.

[0070] As is clear from Figure 6, fresh concrete 12 with a higher slump value (slump value 15.5 cm) is inherently softer and therefore tends to fluidize more easily. On the other hand, fresh concrete 12 with a lower slump value (slump value 6 cm) is inherently harder and therefore tends to fluidize less easily.

[0071] According to this embodiment, the following can be said: In the method for evaluating the fluidity degree of fresh concrete, an evaluation device 11 is used, which includes a weight 21, a float 22 acting on which a larger buoyancy than that of the weight 21 acts, a sensor 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, and an evaluation unit 15 that acquires the change in inclination and evaluates the fluidity degree of the fresh concrete 12. In this method, a measurement sensor 14 is disposed in the fresh concrete 12 in a first position P1 in which the float 22 is positioned below the weight 21, and the measurement sensor 14 is disposed in the fresh concrete 12 in a first position P1 in which the float 22 is positioned below the weight 21. The method includes a first step of inserting an activated or unactivated vibrator 16 near the vibrator 14, and a second step of activating the vibrator 16 to fluidize the ready-mixed concrete 12, and as the ready-mixed concrete 12 fluidizes, the evaluation unit 15 acquires the change in tilt from the measurement sensor 14 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 halfway from the first position P1 to the second position P2, and evaluates the degree of fluidization of the ready-mixed concrete 12 based on the fluctuations in the change in tilt.

[0072] The evaluation device 11 for evaluating the degree of fluidity of fresh concrete has a measurement sensor 14 and an evaluation unit 15, the measurement sensor 14 has a weight portion 21, a float portion 22, and a sensor portion 17, the sensor portion 17 detects a change in inclination of the line segment connecting the weight portion 21 and the float portion 22 relative to the vertical direction, and the evaluation unit 15 receives the change in inclination detected by the sensor portion 17 due to the rotation of the measurement sensor 14 when the measurement sensor 14 is embedded in the fresh concrete, and evaluates the degree of fluidity of the fresh concrete from the change in inclination.

[0073] The measurement sensor 14 is a measurement sensor for measuring the degree of fluidity of the fresh concrete that is inserted into the fresh concrete, and comprises a weight portion 21, a float portion 22 that exerts a greater buoyancy than the weight portion 21, and a sensor portion that detects a change in the inclination of the line segment connecting the weight portion 21 and the float portion 22 relative to the vertical direction.

[0074] Normally, as the action of the vibrator 16 progresses in fluidizing the fresh concrete 12, the frictional force acting within the fresh concrete 12 decreases, causing the fresh concrete 12 to fluidize (liquefy). With the above configuration, the degree of fluidization of the fresh concrete 12 can be evaluated in real time based on the extremely simple principle that the measurement sensor 14 rotates as the frictional force within the fresh concrete 12 decreases. This allows for uniform compaction work regardless of the worker's level of proficiency, ensuring consistent quality.

[0075] The method includes a third step of recovering the measurement sensor 14 from the fresh concrete after the start of the second step.

[0076] According to this configuration, the measurement sensor 14 can be reliably collected.

[0077] The measurement sensor 14 is connected to an extraction jig, and at least a portion of the extraction jig is located outside the fresh concrete 12. In the third step, the extraction jig is extracted to recover the measurement sensor 14 from the fresh concrete 12.

[0078] According to this configuration, the measurement sensor 14 can be extremely easily recovered, and the risk of the measurement sensor 14 remaining in the ready-mixed concrete 12 can be prevented.

[0079] In the second step, the evaluation unit 15 plots a graph of the change in slope and determines the completion of compaction from the time-series data in the graph. According to this configuration, the operator can grasp that fluidization has been completed at a position (for example, a peak position) that is intuitively easy to understand for the operator.

[0080] In the second step, the evaluation unit 15 plots a graph of the change in slope, and predicts the vibration time until compaction is completed from the time series data of the graph. According to these configurations, it is possible to predict the completion of fluidization at a position that is intuitively recognizable to the operator (for example, a peak position, etc.).

[0081] The vibration time predicted to indicate the completion of compaction is determined by determining a point within a specified range of the acceleration graph and the average gradient of the graph at that point, and the time it takes for an extension line with that gradient extended from that point to reach a predetermined change in slope predicted to indicate the completion of compaction. With this configuration, the vibration time that is predicted to complete compaction can be calculated extremely easily.

[0082] The third step is performed before the time when compaction is predicted to be completed, and the operation of the vibrator 16 in the second step is performed until the time when compaction is predicted to be completed. According to this configuration, when the measurement sensor 14 is removed in the third step, it is possible to prevent the removed portion from becoming a cavity (defect).

[0083] The sensor unit has a first detection axis and a second detection axis that are respectively perpendicular to a direction perpendicular to a line segment connecting the weight unit and the float unit, and detects a first acceleration and a second acceleration on the first detection axis and the second detection axis, and calculates a resultant acceleration by the following formula: Resultant acceleration = (1st acceleration 2 +2nd acceleration 2 ) 1 / 2 The gradient of the resultant acceleration is calculated using the following formula: Slope = asin(resultant acceleration).

[0084] According to this configuration, the resultant acceleration can be easily calculated based on the above formula, and the inclination of line segment 27 connecting weight portion 21 and float portion 22 with respect to the vertical direction can be easily calculated from the above formula using this resultant acceleration.

[0085] The umbrella portion 25 is connected to the weight portion 21, has the cable portion 26 passing through the inside thereof, and has an arch-shaped cross-sectional shape that is convex in the direction away from the sensor portion 17. With this configuration, when the measurement sensor 14 is removed from the fresh concrete 12 in the third step, the resistance force acting on the evaluation device 11 is reduced, and it is possible to prevent a large load from being applied to the connecting fitting 24 and the cable portion 26.

[0086] In the following modifications, differences from the first embodiment will be mainly described, and illustrations or descriptions of parts common to the first embodiment will be omitted.

[0087] FIG. 8 shows a first modified example of the measurement sensor 14. In the first modified example, the measurement sensor 14 has a sensor unit 17 disposed outside the housing 23. The measurement sensor 14 has a connection unit 33 that connects the casing 32 and the weight unit 21. The sensor unit 17 is composed of electronic components. Therefore, the surface of the sensor unit 17 is coated with a waterproof resin (not shown) or is covered with a waterproof cover. The casing 32 is made of a synthetic resin material. The covering layer of the cable unit 26 (string) is fixed inside the weight unit 21 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the electric wire of the cable unit 26 (string) is omitted. In this modified example, if the sensor unit 17 and the evaluation unit 15 are connected wirelessly, the cable unit 26 can also be omitted.

[0088] FIG. 9 shows the measurement sensor 14 of the second modified example. In the second modified example, the measurement sensor 14 has the sensor unit 17 disposed inside the weight unit 21. In this modified example, the sensor unit 17 is disposed inside the weight unit 21 and inside the connection unit 33, ensuring that the sensor unit 17 is waterproof. The electric wire of the cable unit 26 (string) electrically connects the evaluation unit 15 and the sensor unit 17. The coating layer of the cable unit 26 is firmly fixed to the weight unit 21 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, if the sensor unit 17 and the evaluation unit 15 are connected wirelessly, the cable unit 26 can be omitted.

[0089] FIG. 10 shows a measurement sensor 14 of a third modified example. In the third modified example, the measurement sensor 14 has a sensor unit 17 disposed outside the weight unit 21. The sensor unit 17 is composed of electronic components. For this reason, the surface of the sensor unit 17 is coated with a waterproof resin (not shown) or is covered with a waterproof cover. The covering layer of the cable unit 26 (string) is fixed to the outside of the weight unit 21 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, if the sensor unit 17 and the evaluation unit 15 are connected wirelessly, the cable unit 26 can be omitted.

[0090] FIG. 11 shows a measurement sensor 14 of a fourth modified example. In the fourth modified example, the measurement sensor 14 has a sensor unit 17 disposed inside the float unit 22. The casing 32 that constitutes the float unit 22 is formed from a synthetic resin material. The covering layer of the cable unit 26 (string) is fixed inside the weight unit 21 and can be used to remove the measurement sensor 14 from the fresh concrete in the third step. In this modified example, if the sensor unit 17 and evaluation unit 15 are connected wirelessly, the cable unit 26 can be omitted.

[0091] FIG. 12 shows the measurement sensor 14 of the fifth modified example. In the fifth modified example, the measurement sensor 14 has a sensor unit 17 disposed outside the float unit 22. The sensor unit 17 is composed of electronic components. For this reason, the surface of the sensor unit 17 is coated with a waterproof resin (not shown) or covered with a waterproof cover. The covering layer of the cable unit 26 (string) is fixed inside the weight unit 21 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the electric wire of the cable unit 26 (string) is omitted. In this modified example, if the sensor unit 17 and the evaluation unit 15 are connected wirelessly, the cable unit 26 can also be omitted.

[0092] FIG. 13 shows a measurement sensor 14 of a sixth modified example. In the sixth modified example, the measurement sensor 14 has a sensor unit 17 disposed outside (below) the weight unit 21. In this modified example, the sensor unit 17 is disposed inside a hollow casing 32, ensuring waterproofing of the sensor unit 17. The casing 32 is formed from a synthetic resin material. The hollow portion inside the casing 32 essentially constitutes the float unit 22. The covering layer of the cable unit 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the cable unit 26 can be omitted if the sensor unit 17 and the evaluation unit 15 are connected wirelessly.

[0093] FIG. 14 shows the measurement sensor 14 of the seventh modified example. In the seventh modified example, the measurement sensor 14 has the sensor unit 17 disposed on the outside (above) of the weight unit 21. In this modified example, the sensor unit 17 is disposed inside a hollow casing 32, ensuring waterproofing of the sensor unit 17. The casing 32 is formed from a synthetic resin material. The hollow portion inside the casing 32 essentially constitutes the float unit 22. The covering layer of the cable unit 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the cable unit 26 can be omitted if the sensor unit 17 and the evaluation unit 15 are connected wirelessly.

[0094] FIG. 15 shows the measurement sensor 14 of the eighth modified example. In the eighth modified example, the measurement sensor 14 has the sensor unit 17 disposed outside the casing 32 and outside the connection unit 33 that connects the casing 32 and the weight unit 21. The sensor unit 17 is composed of electronic components. Therefore, the surface of the sensor unit 17 is coated with a waterproof resin (not shown) or covered with a waterproof cover. The hollow portion inside the casing 32 essentially constitutes the float unit 22. The coating layer of the cable unit 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the electric wire of the cable unit 26 (string) is omitted. In this modified example, the cable unit 26 can be omitted if the sensor unit 17 and the evaluation unit 15 are connected wirelessly.

[0095] FIG. 16 shows a measurement sensor 14 according to a ninth modified example. In the ninth modified example, the measurement sensor 14 has a sensor unit 17 disposed inside the casing 32 and inside the connection unit 33 that connects the casing 32 and the weight unit 21. In this modified example, the sensor unit 17 is disposed inside the hollow casing 32, ensuring waterproofing of the sensor unit 17. The casing 32 is formed from a synthetic resin material. The hollow portion inside the casing 32 essentially constitutes the float unit 22. The covering layer of the cable unit 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the cable unit 26 can be omitted if the sensor unit 17 and the evaluation unit 15 are connected wirelessly.

[0096] FIG. 17 shows a measurement sensor 14 of a tenth modified example. In the tenth modified example, the measurement sensor 14 has a sensor unit 17 disposed on the outside of a casing 32. The sensor unit 17 is composed of electronic components. Therefore, the surface of the sensor unit 17 is coated with a waterproof resin (not shown) or is covered with a waterproof cover. The hollow portion inside the casing 32 essentially constitutes the float portion 22. The covering layer of the cable portion 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, if the sensor unit 17 and the evaluation unit 15 are connected wirelessly, the cable portion 26 can be omitted.

[0097] FIG. 18 shows the measurement sensor 14 of the eleventh modified example. In the eleventh modified example, the measurement sensor 14 has the sensor unit 17 disposed at the bottom of the casing 32 and inside the casing 32. In this modified example, the sensor unit 17 is disposed inside the hollow casing 32, ensuring waterproofing of the sensor unit 17. The casing 32 is formed from a synthetic resin material. The hollow portion inside the casing 32 essentially constitutes the float unit 22. The covering layer of the cable unit 26 (string) is fixed to the outside of the casing 32 and can be used to remove the measurement sensor 14 from the ready-mixed concrete in the third step. In this modified example, the cable unit 26 can be omitted if the sensor unit 17 and the evaluation unit 15 are connected wirelessly.

[0098] FIG. 19 shows a measurement sensor 14 according to a twelfth modification. In the twelfth modification, the measurement sensor 14 has a sensor unit 17 and a wireless circuit (not shown) disposed adjacent to the sensor unit 17 inside the connection unit 33. The measurement sensor 14 houses a battery 41 (e.g., a button-type battery) between the connection unit 33 and the casing 32. The battery 41 (capacitor) can supply power to the sensor unit 17 and the wireless circuit. In this modification, the sensor unit 17 is disposed inside the connection unit 33, ensuring waterproofing of the sensor unit 17. In this modification, the cable unit 26 is omitted because the sensor unit 17 (wireless circuit) and the evaluation unit 15 are connected wirelessly. In this modification, the through-hole of the weight unit 21 is sealed by a sealing member (not shown), such as a rubber stopper.

[0099] FIG. 20 shows a measurement sensor 14 according to a thirteenth modification. In the thirteenth modification, the measurement sensor 14 has a sensor unit 17 and a wireless circuit (not shown) disposed adjacent to the sensor unit 17 inside the connection unit 33. The measurement sensor 14 houses a battery 41 (e.g., a button-type battery) between the connection unit 33 and the casing 32. The battery 41 (capacitor) can supply power to the sensor unit 17 and the wireless circuit. The battery 41 is fixed to the connection unit 33 by a cylindrical connector 42 with a bottom. In this modification, the sensor unit 17 is disposed inside the casing 32, ensuring waterproofing of the sensor unit 17. In this modification, the cable unit 26 is omitted because the sensor unit 17 (wireless circuit) and the evaluation unit 15 are connected wirelessly.

[0100] FIG. 21 shows a measurement sensor 14 according to a fourteenth modification. In this modification, the measurement sensor 14 has a sensor unit 17 disposed inside the connection unit 33. In this modification, the sensor unit 17 is disposed inside the connection unit 33, ensuring waterproofing of the sensor unit 17. The measurement sensor 14 has a battery 41 (e.g., a button-type battery) fixed to the connection unit 33. The battery 41 (capacitor) can supply power to the sensor unit 17 and the wireless circuit. In this modification, the battery 41 also serves as the weight unit 21. The battery 41 also serves as a lid that closes the opening of the connection unit 33. The casing 32 is made of a synthetic resin material. The hollow portion inside the casing 32 essentially constitutes the float unit 22. In this modification, the cable unit 26 is omitted because the sensor unit 17 (wireless circuit) and the evaluation unit 15 are connected wirelessly.

[0101] FIG. 22 shows a measurement sensor 14 according to a fifteenth modification. In this modification, the measurement sensor 14 has a sensor unit 17 and a wireless circuit (not shown) disposed adjacent to the sensor unit 17 inside a connector 42. The measurement sensor 14 has a battery 41 (e.g., a button-type battery) located adjacent to the sensor unit 17 inside the connector 42. The battery 41 (capacitor) can supply power to the sensor unit 17 and the wireless circuit. In this modification, the battery 41 also serves as the weight 21. The battery 41 is fixed to the connection unit 33 by a cylindrical connector 42 with a bottom. In this modification, the sensor unit 17 is disposed inside the casing 32, ensuring waterproofing of the sensor unit 17. In this modification, the cable 26 is omitted because the sensor unit 17 (wireless circuit) and the evaluation unit 15 are connected wirelessly.

[0102] In the following embodiment, differences from the first embodiment will be mainly described, and illustrations or descriptions of parts common to the first embodiment will be omitted. [Second embodiment]

[0103] The evaluation device according to the second embodiment will be described with reference to FIGS. 1 to 5, 23 and 24. FIG. 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 a detection direction axis in a direction along line segment 27 connecting weight portion 21 and float portion 22. This sensor unit 17 (acceleration sensor) has a detection direction axis in a direction along 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 along the detection direction axis.

[0104] That is, as shown in FIG. 5, when evaluation device 11 is in first posture P1 in which float portion 22 is positioned below weight portion 21, the direction of line segment 27 connecting weight portion 21 and float portion 22 substantially coincides with vertical direction G. In this case, the direction of line segment 27 connecting weight portion 21 and float portion 22 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 a detection direction axis (detection sensitivity) in the Z axis direction. Furthermore, when in first posture P1, the Z axis substantially coincides with vertical direction G.

[0105] The evaluation unit 15 can output the acceleration in the Z-axis direction detected by the sensor unit 17 as a graph on the display unit 15A.

[0106] Next, a method for evaluating the fluidity degree of ready-mixed concrete using the evaluation device 11 for evaluating the fluidity degree of ready-mixed concrete of this embodiment will be described with reference to Figure 23. In the evaluation method of this embodiment, two types of ready-mixed concrete 12 with different slump values ​​(slump value 6 cm and slump value 15.5 cm) were used. In addition, in the graph of Figure 23, when the line segment 27 connecting the weight portion and the float portion is positioned along the vertical direction (when in the first attitude P1), the acceleration displayed on the display unit 15A of the evaluation unit 15 corresponds to the gravitational acceleration itself (i.e., 1 G).

[0107] A worker who wishes to compact the ready-mixed concrete 12 pours the ready-mixed concrete 12 into a formwork 13. The state shown in Figures 1 and 2 shows a state in which an upper layer 12B of ready-mixed concrete 12 to be compacted has been newly poured on top of the lower layer 12A of ready-mixed concrete 12 that has already been poured.

[0108] Generally, a worker operates the vibrator 16 and places it at an appropriate position in the ready-mixed concrete 12. At this time, the tip of the vibrator 16 is inserted into the ready-mixed concrete 12 in the lower layer 12A to a position, for example, about 100 mm.

[0109] In the first step, the vibrator 16 is placed near the measurement sensor 14, i.e., at a position, for example, 200 mm from the measurement sensor 14. The measurement sensor 14 is placed, for example, 200 mm from the surface of the ready-mixed concrete 12 in the upper layer 12B, using a device equipped with an insertion rod or rod tool. At this time, the measurement sensor 14 is placed in a first position P1 in which the float portion 22 is positioned below the weight portion 21.

[0110] In the second step, the vibration of vibrator 16 causes gradual fluidization (compaction) around vibrator 16, particularly within a radius of, for example, about 250 mm from the vibrator if the diameter of vibrator 16 is 50 mm. As the fresh concrete 12 around vibrator 16 gradually fluidizes, the frictional force acting on measurement sensor 14 gradually decreases. Then, as the frictional force acting on measurement sensor 14 decreases, the effect of buoyancy acting on float portion 22 increases, and measurement sensor 14 moves from first position P1 to second position P2 in which float portion 22 is positioned above weight portion 21, as shown in FIG. 5.

[0111] When the measurement sensor 14 is in the first attitude P1, the Z-axis direction shown in FIG. 5 substantially coincides with the vertical direction G, and therefore the acceleration is approximately 1 as shown in FIG.

[0112] As the fresh 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, as shown in Figure 23, the acceleration detected in the Z-axis direction by the sensor portion 17 assumes a value close to 0G.

[0113] In the second step, as the operation of the vibrator 16 continues, the degree of fluidization of the ready-mixed concrete 12 further progresses, and as shown in FIG. 5, the measurement sensor 14 rotates from the intermediate position P0 to the second position P2.

[0114] The evaluation unit 15 may determine an arbitrary point J on the graph. That is, as shown in Fig. 24, the evaluation unit 15 may determine the average gradient of the graph at point J, and determine the vibration time predicted as compaction completion as the time until an extension line K having the gradient extended from point J reaches a preset acceleration L predicted as compaction completion. Here, the acceleration predicted as compaction completion is appropriately set based on the relationship between acceleration and the quality of the concrete after hardening.

[0115] After removing the measurement sensor 14, the worker continues to operate the vibrator 16 for several to several tens of seconds to achieve the desired degree of compaction of the ready-mixed concrete 12. In this case, by continuing to operate the vibrator 16 even after removing the measurement sensor 14, the cavity where the measurement sensor 14 was removed can be filled with fluidized ready-mixed concrete 12. This prevents the area where the measurement sensor 14 was removed from becoming a defect.

[0116] After compaction at this position is complete, the worker inserts the vibrator 16 into the ready-mixed concrete 12 at another position within the formwork 13 and carries out steps 1 to 3. In this way, by moving the vibrator 16 and the measurement sensor 14 sequentially or simultaneously within the formwork 13, all of the ready-mixed concrete 12 within the formwork 13 is made to flow uniformly. This completes the compaction work.

[0117] As is clear from Figure 23, fresh concrete 12 with a higher slump value (slump value 15.5 cm) is inherently softer and therefore tends to fluidize more easily. On the other hand, fresh concrete 12 with a lower slump value (slump value 6 cm) is inherently harder and therefore tends to fluidize less easily.

[0118] The above-described embodiments can be implemented with various substitutions and modifications. For example, the sensor unit 17 of the first embodiment may be combined with the sensor unit 17 of the second embodiment. That is, when the measurement sensor 14 is in the first posture P1, the detection direction axes of the sensor unit 17 may be both the vertical direction (Z-axis direction) and directions (X-axis direction and Y-axis direction) perpendicular to the vertical direction (Z-axis direction). In this case, as shown in FIG. 25 , the evaluation unit 15 may display on a graph the change in tilt (resultant acceleration in the X-axis and Y-axis directions) in the directions perpendicular to the vertical direction (Z-axis direction) before and after the posture of the measurement sensor 14 reaches the intermediate posture P0. In this case, as in the first embodiment, the evaluation unit 15 may determine any one point D or E within a predetermined range outside the peak value of the graph. 25, the evaluation unit 15 may determine the average gradient of the graph at that point, and may determine the vibration time predicted to be the compaction completion time as the time until extension lines F, G having the gradient extended from that point reach preset resultant accelerations H, I predicted to be the compaction completion time. Here, the resultant acceleration predicted to be the compaction completion time may be set appropriately based on the relationship between the resultant acceleration and the quality of the concrete after hardening.

[0119] Furthermore, when the measurement sensor 14 is in the intermediate position P0 or before or after it reaches the intermediate position P0, the change in tilt in the vertical direction (Z-axis direction) (Z-axis direction acceleration) may be displayed on the graph. The evaluation unit 15 may determine an arbitrary point J on the graph. That is, as shown in FIG. 25, the evaluation unit 15 may calculate the average gradient of the graph at the point J, and determine the vibration time predicted as compaction completion as the time it takes for an extension line K having the gradient extended from the point J to reach a predetermined acceleration L predicted as compaction completion. Here, the acceleration predicted as compaction completion may be set appropriately based on the relationship between acceleration and the quality of the hardened concrete. [Explanation of symbols]

[0120] 11 Evaluation equipment 12 Ready-mix concrete 14 Measurement Sensor 15 Evaluation Section 16 Vibrator 17 Sensor section 21 Weight 22 Float section 23 Case 25 Umbrella section 26 Cable section 27 line segments P1 1st posture P0 intermediate posture P2 2nd posture

Claims

1. A method for evaluating the fluidity of ready-mixed concrete using an evaluation device having a measurement sensor including a weight portion, a float portion acting on the weight portion with a buoyancy greater than that of the weight portion, and a sensor portion that detects a change in inclination of a line segment connecting the weight portion and the float portion relative to a vertical direction, and an evaluation portion that acquires the change in inclination and evaluates the fluidity of the ready-mixed concrete, a first step of installing the measurement sensor in a first posture in which the float portion is positioned lower than the weight portion in the fresh concrete, and inserting an activated or unactivated vibrator near the measurement sensor; a second step of operating the vibrator to vibrate the fresh concrete and fluidize the fresh concrete, and as the fresh concrete fluidizes, acquiring the change in inclination from the measurement sensor by the evaluation unit 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, and evaluating the degree of fluidization of the fresh concrete based on time-series data of the change in inclination; A method for evaluating the degree of fluidity of ready-mixed concrete.

2. The method for evaluating the degree of fluidity of ready-mixed concrete according to claim 1, further comprising a third step of recovering the measurement sensor from the ready-mixed concrete after the start of the second step.

3. The method for evaluating the degree of fluidity of fresh concrete described in claim 2, wherein the measurement sensor is connected to an extraction jig, and at least a portion of the extraction jig is located outside the fresh concrete, and in the third step, the measurement sensor is recovered from the fresh concrete by extracting the extraction jig.

4. 4. The method for evaluating the degree of fluidization of ready-mixed concrete according to claim 1, wherein in the second step, the evaluation unit draws a graph of the change in slope and determines the completion of compaction from the time series data of the graph.

5. 4. The method for evaluating the degree of fluidization of ready-mixed concrete according to claim 1, wherein in the second step, the evaluation unit plots a graph of the change in slope and predicts the vibration time until compaction is completed from the time series data of the graph.

6. The method for evaluating the degree of fluidity of fresh concrete described in claim 5, wherein the vibration time until compaction is completed is determined by determining a point within a predetermined range of the graph of the slope change and the average slope of the graph at that point, and the time until an extension line with the slope extended from that point reaches a predetermined slope change that determines that compaction is completed.

7. 4. The method for evaluating the degree of fluidity of ready-mixed concrete according to claim 2 or 3, wherein the third step is performed before the completion of compaction, and the vibration of the ready-mixed concrete by the vibrator is performed until the time when the compaction is completed.

8. The sensor unit has a first detection axis and a second detection axis that are respectively perpendicular to a direction perpendicular to a line segment connecting the weight unit and the float unit, and detects a first acceleration and a second acceleration on the first detection axis and the second detection axis, and calculates a resultant acceleration by the following formula: Composite acceleration = (1st acceleration ２ + Second acceleration ２ ) １／２ The gradient of the resultant acceleration is calculated using the following formula: Slope = asin (resultant acceleration) The method for evaluating the fluidity degree of ready-mixed concrete according to any one of claims 1 to 3.

9. A sensor for measuring the degree of fluidity of the ready-mixed concrete, which is inserted into the ready-mixed concrete, A weight portion, a float portion on which a buoyancy greater than that of the weight portion acts; a sensor unit that detects a change in the inclination of a line segment connecting the weight unit and the float unit with respect to a vertical direction; A measurement sensor comprising:

10. 10. The measurement sensor according to claim 9, wherein the sensor unit detects acceleration, and the change in tilt is detected by the change in acceleration.

11. 11. The measurement sensor according to claim 9, wherein the sensor portion has at least one detection axis in a direction perpendicular to a line segment connecting the weight portion and the float portion.

12. 11. The measurement sensor according to claim 9, wherein the sensor portion has a detection axis in a direction parallel to a line segment connecting the weight portion and the float portion.

13. 11. The measurement sensor according to claim 9 or claim 10, wherein the sensor unit has a capacitor, operates on power supplied from the capacitor, and the capacitor is located on the side of the weight unit on a line segment connecting the weight unit and the float unit.

14. The measurement sensor according to claim 13, wherein the capacitor is the weight portion.

15. The measurement sensor has an umbrella portion, the umbrella portion is located outside the weight portion on a line segment connecting the weight portion and the float portion, 11. The measurement sensor according to claim 9, wherein the umbrella portion has an arch-shaped cross section that is convex in a direction away from the weight portion.

16. An apparatus for evaluating the degree of fluidity of ready-mixed concrete, the apparatus having a measurement sensor and an evaluation unit, the measurement sensor having a weight unit, a float unit, and a sensor unit, the sensor unit detects a change in inclination of a line segment connecting the weight unit and the float unit with respect to a vertical direction, The evaluation device is characterized in that the evaluation unit receives the change in tilt detected by the sensor unit due to the rotation of the measurement sensor when the measurement sensor is embedded in the fresh concrete, and evaluates the degree of fluidity of the fresh concrete from the change in tilt.

17. The evaluation device according to claim 16, wherein the evaluation unit determines completion of compaction of the ready-mixed concrete from the time-series data of the change in slope.

18. The evaluation device according to claim 16, wherein the evaluation unit predicts a vibration time until compaction of the ready-mixed concrete is completed from the time-series data of the change in slope.

Images