Method and apparatus for evaluating fresh concrete

Abstract

The purpose is to simultaneously evaluate the fluidity of fresh concrete and the mixing state of cement paste and aggregate. [Solution] A time-sequential image of flowing fresh concrete is acquired, the displacement per unit time of a specific aggregate appearing on the surface of the fresh concrete is measured from the acquired image, the flow velocity of the aggregate is calculated from the displacement per unit time, and the relationship between the flow velocity of the aggregate and the slump of the fresh concrete is recorded in a data table, and the slump of the fresh concrete is evaluated based on the flow velocity of the aggregate.

Description

[Technical Field]

[0001] This disclosure relates to a method and apparatus for evaluating the fluidity and material segregation properties of fresh concrete. [Background technology]

[0002] In all concrete work associated with civil engineering and building construction, the fluidity of fresh concrete and its slump, an indicator of fluidity, are crucial elements for construction management and quality control. The slump of fresh concrete decreases over time and is significantly affected by ambient temperature. Therefore, it is important to monitor the slump continuously at the site where the fresh concrete is poured, and to do so in real time. Furthermore, managing the cement paste and aggregate (especially coarse aggregate) to prevent separation and unevenness is also important for ensuring the quality of the concrete after hardening.

[0003] The fluidity of concrete is generally evaluated using the slump flow test specified in the Japanese Industrial Standards (JIS). However, the JIS method requires sampling fresh concrete, filling it into a slump cone, and then performing the test, which is time-consuming. Therefore, it is difficult to continuously track the slump value as it changes over time.

[0004] Therefore, methods have been proposed to evaluate the fluidity of fresh concrete, including a method for determining the flow rate and velocity from video footage of fresh concrete flowing down a chute of an agitator truck to identify the slump and slump flow (see Patent Document 1), a method for attaching a partitioned inclined flow tester to the chute of an agitator truck, determining the flow tip velocity and height of the fresh concrete flowing down the inclined flow section at an arbitrary measurement point, and determining the apparent yield value and apparent plastic viscosity based on these measurements (see Patent Document 2), and a system for predicting the quality of fresh concrete by filming the fresh concrete being mixed and analyzing multiple image data taken at different times using artificial intelligence (AI) (see Patent Document 3). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-116454 [Patent Document 2] Japanese Patent Publication No. 2019-117095 [Patent Document 3] Japanese Patent Publication No. 2024-061301 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The evaluation methods disclosed in Patent Documents 1 to 3 evaluate the flow velocity of fresh concrete using images, and no method has been proposed to evaluate the material segregation state at the same time. In order to maintain and improve the quality of concrete not only when it is placed but also after it has hardened, it is important to simultaneously evaluate the fluidity of fresh concrete in flow and the state of aggregate segregation.

[0007] Therefore, this disclosure aims to evaluate the fluidity of fresh concrete and the mixing state of cement paste and aggregate simultaneously. [Means for solving the problem]

[0008] A method for evaluating fresh concrete according to one embodiment of the present disclosure includes acquiring a time-sequential image of flowing fresh concrete, measuring the displacement per unit time of a specific aggregate appearing on the surface of the fresh concrete from the image, calculating the flow velocity of the aggregate from the displacement per unit time, and evaluating the slump of the fresh concrete from the flow velocity of the aggregate by referring to a data table that records the relationship between the flow velocity of the aggregate and the slump of the fresh concrete.

[0009] A method for evaluating fresh concrete according to one embodiment of the present disclosure includes obtaining a first image at time t and a second image at time t+Δt, which are taken of the surface of flowing fresh concrete; defining the position of a specific aggregate observed in the first image as the first position and the position of a specific aggregate observed in the second image as the second position; determining the displacement of the specific aggregate from the difference between the first position and the second position; calculating the flow velocity of the aggregate by dividing the displacement by Δt; and evaluating the slump of the fresh concrete from the flow velocity of the aggregate by referring to a data table that records the relationship between the flow velocity of the aggregate and the slump of the fresh concrete.

[0010] In a fresh concrete evaluation method according to one embodiment of the present disclosure, the displacement of a specific aggregate may be calculated from the displacement in the X-axis direction and the displacement in the Y-axis direction.

[0011] In a fresh concrete evaluation method according to one embodiment of the present disclosure, the centroid of a specific aggregate may be determined, and the displacement of the specific aggregate may be determined based on the centroid.

[0012] In a fresh concrete evaluation method according to one embodiment of the present disclosure, multiple aggregates may be selected as specific aggregates, the displacement of each of the multiple aggregates may be determined, and the flow velocity of the fresh concrete may be calculated from the average value of the respective displacements.

[0013] In a method for evaluating fresh concrete according to one embodiment of the present disclosure, it may include selecting a plurality of aggregates as specific aggregates present in a first region in a first image, defining the contour of each of the plurality of aggregates, and determining the first total area of ​​the region inside each of the contours of the plurality of aggregates; selecting aggregates corresponding to specific aggregates present in the same region as the first region in a second image, defining the contour of each of the aggregates corresponding to the specific aggregates, and determining the second total area of ​​the region inside each of the contours of the aggregates corresponding to the specific aggregates; and evaluating the degree of material segregation of the fresh concrete by comparing the first total area and the second total area.

[0014] The fresh concrete evaluation method described above may also be performed on-site at the concrete placement site, on unhardened concrete placed in formwork, or simultaneously with vibration compaction of concrete placed in formwork.

[0015] An evaluation device for fresh concrete according to one embodiment of the present disclosure includes: an imaging unit that captures a time-sequential image of flowing fresh concrete; a displacement measurement unit that determines the amount of displacement per unit time of a specific aggregate appearing on the surface of the fresh concrete from the captured image; a calculation unit that calculates the flow velocity of the aggregate from the amount of displacement per unit time; and an evaluation unit that refers to a data table in which the relationship between the flow velocity of the aggregate and the slump of the fresh concrete is recorded, and evaluates the slump of the fresh concrete from the flow velocity of the aggregate.

[0016] An evaluation device for fresh concrete according to one embodiment of the present disclosure includes: an imaging unit that acquires a first image of flowing fresh concrete at time t and a second image at time t+Δt; a displacement measurement unit that determines the displacement of a specific aggregate from the difference between the first position and the second position, with the position of a specific aggregate observed from the first image being the first position and the position of a specific aggregate appearing in the second image being the second position; a calculation unit that calculates the flow velocity of the aggregate by dividing the displacement by Δt; and an evaluation unit that evaluates the slump of the fresh concrete from the flow velocity by referring to a data table in which the relationship between the flow velocity of the aggregate and the slump of the fresh concrete is recorded.

[0017] In a fresh concrete evaluation device according to one embodiment of the present disclosure, the displacement measurement unit may calculate the displacement of a specific aggregate from the displacement in the X-axis direction and the displacement in the Y-axis direction.

[0018] In a fresh concrete evaluation device according to one embodiment of the present disclosure, the displacement measurement unit may determine the displacement of a specific aggregate by finding the centroid of the specific aggregate and determining the displacement of the specific aggregate based on the centroid.

[0019] In the fresh concrete evaluation apparatus according to an embodiment of the present disclosure, the displacement measurement unit selects a plurality of aggregates as specific aggregates, obtains the displacement amount of each of the plurality of aggregates, and the calculation unit may calculate the flow rate of the fresh concrete from the average value of each displacement amount.

[0020] In the fresh concrete evaluation apparatus according to an embodiment of the present disclosure, the displacement measurement unit selects a plurality of aggregates as specific aggregates existing in a first region in a first image, defines the contour of each of the plurality of aggregates, obtains the first total area of the region inside the contour of each of the plurality of aggregates, selects the aggregates corresponding to the specific aggregates existing in the same region as the first region in a second image, defines the contour of each of the aggregates corresponding to the specific aggregates, obtains the second total area of the region inside the contour of each of the aggregates corresponding to the specific aggregates, the calculation unit calculates the amount of change or the rate of change between the first total area and the second total area, and the evaluation unit may evaluate the degree of material separation of the fresh concrete from the amount of change or the rate of change.

Effect of the Invention

[0021] According to an embodiment of the present disclosure, by evaluating the fluidity and segregation resistance of flowing fresh concrete, it is possible to grasp changes in fluidity and a decrease in segregation resistance, and prevent various problems that occur during the placement of fresh concrete. As a result, the quality of concrete structures can be managed, and durability can be improved.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram for explaining a fresh concrete evaluation method according to an embodiment of the present disclosure. [Figure 2] It is a diagram for explaining a fresh concrete evaluation method according to an embodiment of the present disclosure. [Figure 3] It is a diagram for explaining a fresh concrete evaluation method according to an embodiment of the present disclosure. [Figure 4] This diagram illustrates the relationship between slump and aggregate flow velocity using a graph. [Figure 5] This figure illustrates a method for evaluating fresh concrete according to one embodiment of the present disclosure. [Figure 6] This figure shows the configuration of a fresh concrete evaluation device according to one embodiment of the present disclosure. [Figure 7] This diagram illustrates the processing flow of a fresh concrete evaluation method according to one embodiment of the present disclosure. [Figure 8] This diagram illustrates the processing flow of a fresh concrete evaluation method according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the length, width, height, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals (or numerals followed by A, B, etc.), and detailed explanations may be omitted as appropriate. Furthermore, the letters "1st," "2nd," etc., attached to each element are convenient indicators used to distinguish each element and have no further meaning unless specifically explained.

[0024] In this disclosure, "fresh concrete" refers to concrete that has been poured into formwork immediately after mixing and has not yet hardened. However, in the following explanation, unless otherwise specified, it will simply be referred to as "concrete." To distinguish it from this, hardened concrete will be referred to as "hardened concrete," "concrete after hardening," etc.

[0025] Figure 1 illustrates the concept of the concrete evaluation method according to this disclosure. Figure 1 shows an image at time t extracted from a series of still images or a video of flowing concrete, and an image at time t+Δt, which is Δt after time t. The images may be taken from above the concrete surface, or from an oblique or side view. However, the image at time t and the image at time t+Δt that are to be compared must have the same camera position, field of view, and magnification.

[0026] The value of Δt can be set as appropriate. Δt can be set to a time of 1 second or less; for example, Δt = 0.5 seconds. Depending on the concrete flow rate, Δt can also be set to a time longer than 1 second; for example, Δt = 1.5 seconds.

[0027] On the surface of flowing concrete, cement paste and aggregates to which the cement paste is attached become visible. When the concrete surface is photographed with a camera, the presence of aggregates can be confirmed by the differences in gloss, shadows, and contrast caused by the exposure to ambient light. Within the flowing concrete, the aggregates move together with the cement paste.

[0028] Figure 1 schematically shows that aggregates 10A, 10B, 10C, and 10D are present in cement paste CP. Since concrete is fluid, the positions of aggregates 10A, 10B, 10C, and 10D also change over time. For example, if we represent the positions of the aggregates appearing in the image using XY coordinates, aggregate 10A is at position (x1, y1) at time t and moves to position (x1+Δx, y1+Δy) at time t+Δt. Similarly, aggregate 10B is at position (x2, y2) at time t and moves to position (x2+Δx, y2+Δy) at time t+Δt. In other words, between time t and time t+Δt, aggregates 10A and 10B move by Δx in the X-axis direction and Δy in the Y-axis direction. Therefore, the movement distance in the X-axis direction and the movement distance in the Y-axis direction of aggregates 10A and 10B are divided by Δt, respectively, to obtain the movement velocity in the X-axis direction (Vx ) and Y-axis movement speed (V y If we find the moving speed of aggregates 10A and 10B (V=(V x 2 +V y 2 ) 1 / 2 This allows us to determine the slump. In this disclosure, the slump is evaluated by assuming that the movement speed of aggregates 10A and 10B is equal to the flow speed of the concrete.

[0029] The flow velocity of aggregates is captured by an imaging device such as a digital camera and analyzed using the image displayed on a computer screen. In this analysis, screen coordinates may be used as the coordinate system representing the position of the aggregates. To convert screen coordinates to actual lengths, a conversion formula between logical coordinates on the computer screen and actual size coordinates on the screen can be used. When identifying the position of aggregates, characteristic parts of the aggregates observed on the screen can be used as measurement points. For example, within a single aggregate, parts that appear sharper or have stronger contrast compared to other parts can be selected. Alternatively, the outline of the aggregates as seen externally can be taken, the area enclosed by the outline can be set as a planar figure, the centroid of that planar figure can be found, and that centroid can be used as a measurement point.

[0030] Figure 1 shows an example where aggregates 10A and 10B move in the same direction and for the same distance, for the sake of simplicity. However, in reality, each aggregate moves irregularly within flowing concrete. For example, as shown in Figure 2, aggregate 10A, which was at position (x1, y1) at time t, moves to (x1+Δxa, y1+Δya) at time t+Δt, and aggregate 10B, which was at (x2, y2) at time t, moves to (x2+Δxb, y2+Δyb) at time t+Δt. Here, we assume that xa ≠ xb and ya ≠ yb. In such cases, the respective movement velocities of aggregates 10A and 10b can be calculated, the average value of the aggregate flow velocities can be found, and this average value can be evaluated as the flow velocity of the concrete. In Figure 2, we focused on two aggregates, 10A and 10B. However, by performing calculations for other aggregates, 10C and 10D, we can increase the number of aggregates used in the calculations and improve the accuracy of evaluating the flow velocity of concrete.

[0031] In flowing concrete, aggregates may move while rotating irregularly. Figure 3 schematically shows the state of aggregates flowing with rotation. When aggregates rotate, as shown in Figure 1, if a single point on the aggregate is used as the measurement point, there is a concern that the distance traveled may not be accurately measured depending on the size of the aggregate. In such cases, as explained above, by treating the area enclosed by the contour of the aggregate as a planar figure, finding the centroid of that planar figure, and using that centroid as the measurement point, the accuracy of measuring the distance traveled can be improved, and a more accurate flow velocity can be determined.

[0032] Concrete slump is a value that represents the degree of softness and is usually determined by a slump test. The flow velocity of aggregates has a certain relationship with the slump value, as the flow velocity increases when the concrete is soft and decreases when it hardens. Figure 4 is a graph showing the relationship between slump and aggregate flow velocity. Since the preferred numerical range for slump is known, the preferred range for flow velocity can be determined from that numerical range.

[0033] The relationship between concrete slump and aggregate flow velocity, as shown in Figure 4, can be obtained by evaluating pre-prepared concrete samples. Specifically, by preparing several samples with varying concrete softness and measuring the aggregate flow velocity and performing slump tests, the correspondence between the aggregate flow velocity obtained by this evaluation method and the slump value obtained by the slump test can be obtained. However, the characteristics shown in the graph of Figure 4 differ depending on the type of aggregate, rock type, and unit cement content of the concrete; therefore, the same aggregate flow velocity may not be obtained even with the same slump value. For this reason, by measuring the aggregate flow velocity during slump tests for concrete produced under various manufacturing conditions and accumulating the data, it is possible to correlate it with the slump value and evaluate changes in slump.

[0034] Furthermore, the flow velocity of aggregates also changes depending on the angle of the chute through which the concrete flows and the discharge pressure of the concrete pump. Therefore, by accumulating data on various conditions during concrete placement, such as the chute angle and discharge pressure, it is possible to correlate this data with the slump value and evaluate changes in the slump.

[0035] The method for evaluating concrete slump described in this disclosure allows for on-site measurement during concrete placement and immediate evaluation of the results. If the evaluation results are favorable and the concrete has the predetermined slump, construction can continue as is. On the other hand, if the evaluation results are unfavorable and the concrete slump falls outside the set range, it is desirable to immediately stop concrete placement and replace the agitator truck. However, concrete may remain in the pump truck or agitator truck. In such cases, since the slump value tends to decrease over time, measures can be taken by adding superplasticizers or water-reducing agents prepared on-site to restore the slump of the remaining concrete to the appropriate value. Furthermore, if significant changes in slump are observed and it frequently exceeds the appropriate slump range, measures can be taken such as contacting the ready-mix concrete plant to have them consider countermeasures for future shipments.

[0036] Furthermore, even if the slump value is within the specified standard range, variations may occur in the quality of the concrete after hardening. Therefore, by investigating the relationship between the measured slump value and the quality of the concrete (e.g., compressive strength, air content, etc.) and accumulating the data, it can be used for research and development aimed at improving concrete, as well as for improving and managing construction methods.

[0037] The above describes a method for evaluating concrete slump from images taken of the concrete surface, but the same images can also be used to evaluate the degree of segregation of materials in the concrete. Segregation is a phenomenon in which the distribution of materials constituting the concrete becomes uneven during or after concrete placement, such as the localized concentration of coarse aggregate or the concentration of water on the surface of the concrete. A high degree of segregation is undesirable because it leads to an uneven distribution of materials in the hardened concrete, resulting in a decrease in quality.

[0038] Figure 5 illustrates a conceptual method for evaluating the degree of material segregation in concrete. Figure 5 is a schematic diagram of images of the concrete surface at time t and time t+Δt, showing that aggregates 10A, 10B, 10C, and 10D are present in the cement paste CP. To evaluate material segregation, the contours of the regions recognized as aggregates are defined, and the area within the regions enclosed by these contours is calculated. For example, in the image at time t, the contours of aggregates 10A, 10B, 10C, and 10D present in the region R under observation are defined, and the areas S1, S2, S3, and S4 of the regions enclosed by these contours are calculated, and their total area S (=S1+S2+S3+S4) is then calculated. The ratio RT1 (=S / SR) of the area S occupied by aggregates to the area SR of region R is then calculated. Subsequently, a similar evaluation is performed using the image at time t+Δt. Specifically, the areas S1', S2', S3', and S4' of the aggregate are determined, and the ratio of the area S' occupied by the aggregate to the area SR of region R is calculated as RT2 (= S' / SR).

[0039] The degree of segregation in concrete can be evaluated by comparing RT1 and RT2. Specifically, a small difference between RT1 and RT2 indicates a small degree of segregation, while a large difference between RT1 and RT2 indicates a large degree of segregation.

[0040] The images used for evaluation may be images of the surface of flowing concrete during concrete placement, or images of the stationary concrete surface sampled in a predetermined container before concrete placement. Furthermore, this evaluation may be based on the total area of ​​all aggregates contained within region R, on the total area of ​​aggregates of a predetermined size or larger, or on the total area of ​​arbitrarily selected aggregates within region R.

[0041] Furthermore, as explained in Figures 1 to 3, by understanding the movement speed of aggregates in the X-axis and Y-axis directions, it is possible to predict a decrease in the segregation resistance of concrete. When making this prediction, an appropriate range for the flow velocity of the aggregates is set, and aggregates with movement velocities that deviate significantly from this range are extracted. A range is also set for these deviating flow velocities, and predetermined thresholds are set for the percentage of the deviation, such as an increase (high speed side) or decrease (low speed side) of 50% or more or 75% or more. If the flow velocity of the aggregates exceeds the high-speed threshold, it can be judged that the degree of material segregation is large, and if it exceeds the low-speed threshold, it can be judged that the degree of material segregation is small or that the fluidity has decreased. In addition, if the aggregates sink into the cement paste or disappear from the screen, a certain loss rate can be set, and the data can be processed so that it is not treated as data. By capturing the movement of as many aggregates as possible and averaging it, the actual characteristics can be obtained.

[0042] This evaluation method allows for the simultaneous assessment of slump and segregation during concrete placement. Because this method utilizes image analysis, it can be performed in real-time at the construction site while concrete is being placed, allowing for immediate evaluation of the results. If the evaluation is favorable and the degree of segregation is low, construction can continue. On the other hand, if the evaluation is unfavorable and the degree of segregation is high, it is advisable to immediately stop concrete placement, visually inspect the condition of the placed concrete, and consider replacing the agitator truck. However, since concrete segregation is influenced not only by the inherent properties of the material but also by the flow rate, pumping, and the use of the vibration compactor during placement, it is also advisable to consider reviewing these construction methods. Furthermore, if the segregation is significantly high, it is possible to contact the ready-mix concrete plant to request measures for future shipments. By performing such evaluations in real-time, construction can be carried out while ensuring the required quality.

[0043] Figure 6 shows the configuration of a device for evaluating the slump and material segregation of concrete. The concrete evaluation device 100 includes an imaging unit 102, an image processing unit 104, a displacement measurement unit 106, a calculation unit 108, an evaluation unit 110, and a display unit 114.

[0044] The imaging unit 102 has the function of acquiring images of the concrete surface as digital data. The imaging unit 102 is installed facing the channel 202 through which the concrete 200 flows. It is preferable that the angle of the imaging unit 102 be constant, and it is preferable that a support column or tripod be used to fix the imaging unit 102 in place. The imaging unit 102 may also have a buffer function (buffer memory) for temporarily storing captured images and a storage function (memory card, etc.) for saving captured images.

[0045] The concrete flow path 202 may be a chute for an agitator truck or a concrete pumping pipe. If the flow path 202 is a chute for an agitator truck, it is preferable to install the imaging unit 102 above the chute. If the flow path 202 is a concrete pumping pipe, the imaging unit 102 can be installed facing the concrete discharge port. Alternatively, the flow path 202 through which the concrete flows may be replaced with a formwork 204 into which concrete has been poured, and the imaging unit 102 may be installed to photograph the concrete flowing through the formwork 204 or the concrete flowing due to a vibratory compaction machine.

[0046] The image processing unit 104 performs predetermined image processing on the images taken by the imaging unit 102 at time t and time t+Δt. For example, as explained with reference to Figure 1, it has the function of identifying aggregate in cement paste based on differences in contrast, setting feature points and their screen coordinates, extracting the contours of the aggregate and finding the centroid of the region enclosed by the contours, and calculating the area of ​​the region enclosed by the contours of the aggregate. The image processing unit 104 performs at least one of these processes.

[0047] The displacement measurement unit 106 has a function of calculating the displacement amount of the aggregate from the image at time t and the image at time t+Δt. For example, when obtaining the displacement amount of the feature points of the aggregate as described with reference to FIGS. 1, 2, and 3, the displacement amounts Δx and Δy are calculated from the coordinates (x, y) of the feature points at time t and the coordinates (x+Δx, y+Δy) at time t+Δt. When the coordinates are based on the screen coordinates, the displacement amounts Δx and Δy are converted to actual dimensions.

[0048] Also, as described with reference to FIG. 5, when obtaining the area of the region identified as the aggregate, the area of the aggregate at time t and at time t+Δt is calculated.

[0049] The calculation unit 108 has a function of calculating the flow velocity of the aggregate. For example, the flow velocity of the aggregate is calculated from the displacement amounts Δx and Δy of the aggregate between time t and time t+Δt. The flow velocity of the aggregate is, for example, obtained by dividing the displacement amounts Δx and Δy by Δt respectively to obtain the moving velocity Vx in the X-axis direction and the moving velocity Vy in the Y-axis direction, and then obtaining the moving velocity V(=(Vx 2 +Vy 2 ) 1 / 2 ) from that data.

[0050] Also, the calculation unit 108 calculates the amount of change and the rate of change of how much the area of the region identified as the aggregate obtained by the displacement measurement unit 106 has changed between time t and time t+Δt.

[0051] The evaluation unit 110 has the function of determining whether the slump of the concrete is within an acceptable range based on the aggregate flow velocity calculated by the calculation unit 108. The evaluation unit 110 reads reference data from the data table 112 based on the concrete conditions and measurement conditions to make the determination. The data table 112 records data showing the relationship between concrete slump and aggregate flow velocity for each parameter such as concrete conditions (type of aggregate, type of rock, unit cement amount, etc.) and flow path conditions (chute angle, pump discharge pressure), as shown in Figure 4. The evaluation unit 110 reads data corresponding to the concrete conditions and measurement conditions from the data table to determine whether the slump value is within a set range.

[0052] Furthermore, the evaluation unit 110 evaluates the degree of material separation based on the amount of change in aggregate area and the rate of change in area calculated by the calculation unit 108.

[0053] For example, the evaluation unit 110 may have a function to determine the rate of change of the aggregate area ratio and issue a warning with an alarm sound on the display unit 114 if the rate of change deviates from a preset threshold. The evaluation unit 110 may also have a function to determine the change in area ratio for each zone, such as dividing the video screen into four zones (up, down, left, and right) or, if the concrete is flowing horizontally, dividing it into three zones (upper, middle, and lower), and to determine whether material segregation is occurring overall or partially. Since material segregation is also affected by the flow velocity and the vibration compactor, if it is determined that material segregation has occurred partially due to the use of the vibration compactor, the usage time and insertion depth of the vibration compactor can also be reviewed. In this way, the evaluation device 100 is also useful for improving construction methods. Furthermore, the evaluation unit 110 may have artificial intelligence capabilities, and as "pattern recognition utilizing machine learning," it may collect a large amount of video data, use the state of material segregation as training data, learn patterns of material segregation from past data, and predict slump and segregation state in real time, thereby optimizing construction methods and saving labor.

[0054] The display unit 114 has a function to display the judgment result. The display unit 114 may also have a function to display an image of the concrete surface and markers indicating characteristic points and contours of the aggregate when the image processing unit 104 identifies the aggregate. The display unit 114 may also have a function to display images at time t and time t+Δt simultaneously on a multi-screen display.

[0055] An evaluation device 100 having such functions can be realized by integrating hardware and software resources. The imaging unit 102 is made up of an image sensor such as a CMOS sensor or CCD sensor and an optical system, and is realized by a camera capable of capturing still images and videos. The display unit 114 is realized by a flat panel display such as a liquid crystal panel or an organic EL panel. The image processing unit 104, displacement measurement unit 106, calculation unit 108, and evaluation unit 110 are realized on a computer by a computer program.

[0056] The evaluation device 100 may consist of a camera (imaging unit 102), a computer (image processing unit 104, displacement measurement unit 106, calculation unit 108, evaluation unit 110), and a display (display unit 114) as separate devices connected by wired or wireless connections, or it may be implemented as a tablet terminal, smartphone, or notebook personal computer in which the camera, computer, and display are integrated.

[0057] Figure 7 shows the process flow for evaluating concrete slump. Each process shown in Figure 7 is performed by the evaluation device 100 shown in Figure 6.

[0058] First, the imaging unit 102 takes images of the flowing concrete surface (S200). The images of the flowing concrete surface may be taken continuously as the concrete is poured, or they may be taken intermittently. In other words, each of the following steps may be performed while the concrete surface is being photographed.

[0059] From the captured image data, images at time t and time t+Δt are extracted. The image processing unit 104 selects aggregates from each extracted image and sets measurement points for measuring displacement (distance moved) (S202). This process of setting measurement points may be performed within the computer by an image processing program, or it may be performed by an operator while viewing a display screen.

[0060] Next, the displacement measurement unit 106 sets the position of the measurement point at time t and time t+Δt (S204), and calculates the displacement of the measurement point (S206). The measurement point can be set based on screen coordinates as described above.

[0061] The calculation unit 108 calculates the aggregate flow velocity based on the displacement of the measurement point (S208). The calculation of the aggregate flow velocity is as described above. Then, the evaluation unit 110 estimates the concrete slump based on the aggregate flow velocity (S210) and determines whether the slump value is within a preset range of specified values ​​(S212). The slump evaluation is performed by referring to the data recorded in the data table 112. This evaluation result is displayed on the display unit 114, etc., and is also provided to the operator as visually accessible data such as text and images.

[0062] Figure 8 shows the process flow for evaluating the degree of material segregation in concrete. Each process shown in Figure 8 is performed by the evaluation device 100 shown in Figure 6.

[0063] Similar to the example shown in Figure 7, first, the imaging unit 102 captures images of the flowing concrete surface (S250). From the captured image data, images at time t and time t+Δt are extracted, and the image processing unit 104 identifies the aggregates in each extracted image (S252). Then, contours are set for the aggregates identified in the image (within region R) (S254), and the total area of ​​the region enclosed by the contours is calculated (S256).

[0064] Using the calculated total area, the proportion of the area occupied by aggregate on the concrete surface at time t and time t+Δt is calculated (S258). Then, the degree of material segregation is evaluated from the change in the amount or rate of change of the area occupied by aggregate at time t and time t+Δt (S260). This evaluation result is displayed on the display unit 114, etc., and is also provided to the worker as visually accessible data such as text and images.

[0065] The evaluation of the concrete slump shown in steps S200 to S212 in Figure 7 and the evaluation of concrete material segregation shown in steps S250 to S260 in Figure 8 may be performed simultaneously, alternately, or either one at a time using the evaluation device 100 shown in Figure 6.

[0066] As described above, according to one embodiment of this disclosure, the fluidity and degree of material segregation of concrete in flow can be evaluated in real time at the concrete placement site, and also at the construction site where concrete is still fluid after placement. Since the evaluation results can be known by the worker at the same time as the measurement, various defects that occur in concrete work can be prevented, the quality of concrete structures can be managed, and the durability can be improved.

[0067] The concrete evaluation method described herein can be applied to concrete flowing down the chute of an agitator truck, concrete flowing within a formwork when concrete is pumped in, and concrete flowing when compacted with a vibratory compactor.

[0068] The configuration of the concrete evaluation method and the evaluation apparatus as disclosed herein can be combined as appropriate, provided they do not contradict each other. Furthermore, additions, deletions, or modifications to the processing steps of the concrete evaluation method and additions, deletions, or design changes to the components of the evaluation apparatus are also included within the technical scope of the invention as disclosed herein, provided that they do not alter the gist of the disclosure.

[0069] Even if there are effects or benefits other than those achieved by the invention disclosed herein, those that are clear from this disclosure or that can be easily predicted by a person skilled in the art shall naturally be considered to be brought about by the invention disclosed herein. [Explanation of Symbols]

[0070] 10A, 10B, 10, 10D: Aggregate, 100: Evaluation device, 102: Imaging unit, 104: Image processing unit, 106: Displacement measurement unit, 108: Calculation unit, 110: Evaluation unit, 112: Data table, 114: Display unit, 200: Concrete (fresh concrete), 202: Flow channel, 204: Formwork, CP: Cement paste

Claims

1. By acquiring a time-sequential image of flowing fresh concrete, From the aforementioned image, the amount of displacement per unit time of a specific aggregate appearing on the surface of the fresh concrete is measured. The flow velocity of the aggregate is calculated from the displacement per unit time. Refer to a data table that records the relationship between the flow velocity of the aggregate and the slump of the fresh concrete, and evaluate the slump of the fresh concrete from the flow velocity of the aggregate. A method for evaluating fresh concrete characterized by the following features.

2. We obtained a first image at time t and a second image at time t+Δt, both of which were taken of the surface of flowing fresh concrete. The position of a specific aggregate observed in the first image is defined as the first position, and the position of the specific aggregate observed in the second image is defined as the second position. The displacement of the specific aggregate is determined from the difference between the first position and the second position. The displacement is divided by the Δt to calculate the flow velocity of the aggregate. Refer to a data table that records the relationship between the flow velocity of the aggregate and the slump of the fresh concrete, and evaluate the slump of the fresh concrete from the flow velocity of the aggregate. A method for evaluating fresh concrete characterized by the following features.

3. The displacement of the aforementioned specific aggregate is calculated from the displacement in the X-axis direction and the displacement in the Y-axis direction. A method for evaluating fresh concrete according to claim 1 or 2.

4. The center of gravity of the specified aggregate is determined, and the displacement of the specified aggregate is determined based on the center of gravity. A method for evaluating fresh concrete according to claim 1 or 2.

5. Multiple aggregates are selected as the aforementioned specific aggregates, Determine the displacement of each of the aforementioned aggregates, The flow velocity of the fresh concrete is calculated from the average value of each of the aforementioned displacement amounts. A method for evaluating fresh concrete according to claim 1 or 2.

6. In the first image, a plurality of aggregates are selected as the specific aggregates present in the first region, the contours of each of the plurality of aggregates are defined, and the first total area of ​​the region inside the contours of each of the plurality of aggregates is determined. In the second image, select the aggregate corresponding to the specific aggregate that is located within the same region as the first region, define the contour of each of the aggregates corresponding to the specific aggregate, and calculate the second total area of ​​the region inside each of the contours of the aggregates corresponding to the specific aggregate. This includes evaluating the degree of material segregation in the fresh concrete by comparing the first total area with the second total area. The method for evaluating fresh concrete according to claim 2.

7. A method for evaluating fresh concrete, wherein the evaluation method described in any one of claims 1 to 6 is performed at the site where the concrete is poured, on unhardened concrete poured into formwork, or simultaneously at the site when vibrating-compacting concrete poured into formwork.

8. An imaging unit that captures a time-sequential image of flowing fresh concrete, A displacement measurement unit that determines the amount of displacement per unit time of a specific aggregate appearing on the surface of the fresh concrete from the aforementioned image, A calculation unit that calculates the flow velocity of the aggregate from the displacement amount per unit time, Includes an evaluation unit that refers to a data table recording the relationship between the flow velocity of the aggregate and the slump of the fresh concrete, and evaluates the slump of the fresh concrete from the flow velocity of the aggregate. A fresh concrete evaluation device characterized by the following features.

9. An imaging unit that acquires a first image of flowing fresh concrete at time t and a second image at time t + Δt, A displacement measurement unit determines the displacement of a specific aggregate from the difference between the first position and the second position, with the position of the specific aggregate observed in the first image being defined as the first position, and the position of the specific aggregate appearing in the second image being defined as the second position. A calculation unit that calculates the flow velocity of the aggregate by dividing the displacement by the Δt, Includes an evaluation unit that refers to a data table recording the relationship between the flow velocity of the aggregate and the slump of the fresh concrete, and evaluates the slump of the fresh concrete from the flow velocity. A fresh concrete evaluation device characterized by the following features.

10. The displacement measurement unit calculates the displacement of the specific aggregate from the displacement in the X-axis direction and the displacement in the Y-axis direction. The fresh concrete evaluation apparatus according to claim 8 or 9.

11. The displacement measurement unit determines the center of gravity of the specific aggregate and determines the displacement of the specific aggregate based on the center of gravity. The fresh concrete evaluation apparatus according to claim 8 or 9.

12. The displacement measurement unit selects a plurality of aggregates as the specific aggregate, and determines the displacement of each of the plurality of aggregates. The calculation unit calculates the flow velocity of the fresh concrete from the average value of each of the displacement amounts. The fresh concrete evaluation apparatus according to claim 8 or 9.

13. The displacement measurement unit selects a plurality of aggregates as the specific aggregates present in the first region in the first image, defines the contour of each of the plurality of aggregates, and calculates the first total area of ​​the region inside each of the contours of the plurality of aggregates. In the second image, it selects aggregates corresponding to the specific aggregates present in the same region as the first region, defines the contour of each of the aggregates corresponding to the specific aggregates, and calculates the second total area of ​​the region inside each of the contours of the aggregates corresponding to the specific aggregates. The calculation unit calculates the amount or rate of change between the first total area and the second total area, The evaluation unit evaluates the degree of material segregation of the fresh concrete from the amount of change or the rate of change. The fresh concrete evaluation apparatus according to claim 9.

Images