Manufacturing method of recycled aggregate, particle separation method and quality evaluation method

Abstract

To provide a particle separation method that can be suitably applied to a method for producing recycled aggregate, which can efficiently produce recycled aggregate from crushed concrete chunks.SOLUTION: There is provided a method for separating multiple particles obtained by crushing concrete blocks. The method comprises the steps of: acquiring image data of the multiple particles; identifying mortar-rich portions and aggregate-rich portions using the image data; and, on the basis of a result of the identification, separating the multiple particles into multiple particle groups including a first particle group and a second particle group having a lower mortar content in the image data than the first particle group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing recycled aggregate, a method for separating particles, and a method for evaluating quality. [Background technology]

[0002] At demolition sites, waste concrete is generated as industrial waste. There are known techniques for crushing such waste concrete, sorting the crushed material according to its size and contained components, and recovering recycled aggregate. For example, Patent Document 1 proposes a technique for determining the size and area of ​​large aggregates from images and removing them. Patent Document 2 proposes the use of a wet specific gravity separator and a wet cyclone separator as means for separating mortar components from aggregate components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-212778 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-220192 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology to recover aggregate components from crushed concrete blocks, such as waste concrete, and use them as recycled aggregate for concrete has not been widely utilized, and currently most of the waste concrete is used as roadbed material. This is due to the fact that in order to obtain high-quality recycled aggregate, processes such as heating and grinding are required to remove the mortar adhering to the particle surfaces of the crushed material, and it is also time-consuming to measure the density, water absorption, and other parameters used to evaluate the quality of recycled aggregate.

[0005] The present disclosure provides a method for producing recycled aggregate from crushed concrete blocks, which can efficiently produce recycled aggregate, and a particle sorting method that can be suitably applied to such a production method.The present disclosure also provides a quality evaluation method that can simply and quickly evaluate the quality of multiple particles obtained from concrete blocks. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a method for separating a plurality of particles obtained by crushing concrete blocks, the method comprising the steps of: acquiring image data of the plurality of particles; identifying a mortar-rich portion and an aggregate-rich portion using the image data; and, based on the results of the identification, separating the plurality of particles into a plurality of particle groups including a first particle group and a second particle group having a lower mortar content than the first particle group.

[0007] This separation method involves obtaining image data of multiple particles obtained by crushing a concrete block. Because the mortar and aggregate components present in the original concrete block differ in color, and because mortar is often attached to the aggregate particle surface or present as a separate particle in the multiple particles obtained by crushing the concrete block, the difference in particle surface color can be used to quickly and easily distinguish between mortar-rich and aggregate-rich portions. Based on the results of this identification, the separation method separates the multiple particles into multiple particle groups, including a first particle group and a second particle group with a lower mortar content. Because the second particle group obtained by separation has a lower mortar content, this method is suitable for use in a method for producing recycled aggregate.

[0008] One aspect of the present disclosure provides a method for producing recycled aggregate, comprising the step of obtaining recycled aggregate from at least a portion of the second particle group separated by the above-described separation method. In this method, the second particle group having a low mortar content is separated by the above-described separation method, and therefore the recycled aggregate can be produced efficiently.

[0009] One aspect of the present disclosure provides a quality evaluation method for a plurality of particles obtained by crushing a concrete block, the quality evaluation method comprising the steps of: acquiring image data of the plurality of particles; identifying a mortar-rich portion and an aggregate-rich portion using the image data; and deriving an area ratio of at least one of the mortar-rich portion and the aggregate-rich portion in the image data based on the results of the identification.

[0010] This quality evaluation method involves acquiring image data of multiple particles obtained by crushing a concrete block. Mortar and aggregate components differ in color, and in the multiple particles obtained by crushing a concrete block, mortar is often attached to the surface of aggregate particles or exists as individual particles. Therefore, the difference in particle surface color can be used to quickly and easily distinguish between mortar-rich and aggregate-rich portions. Based on the results of this identification, the area ratio of at least one of the mortar-rich and aggregate-rich portions can be derived, allowing the quality of the multiple particles to be easily and quickly evaluated. [Effects of the Invention]

[0011] The present disclosure can provide a method for producing recycled aggregate that can efficiently produce recycled aggregate from crushed concrete blocks, and a particle sorting method that can be suitably applied to such a production method.The present disclosure can provide a quality evaluation method that can simply and quickly evaluate the quality of multiple particles obtained from concrete blocks. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a recycled aggregate manufacturing facility. [Figure 2] 1 is a flowchart of a method for fractionating multiple particles. [Figure 3] FIG. 1 is a diagram showing a fractionation device used in a method for fractionating a plurality of particles. [Figure 4] 1A is a diagram illustrating an example of a method for separating a plurality of particles, and FIG. 1B is a diagram illustrating another example of a method for separating a plurality of particles. [Figure 5] (A) is image data of multiple particles before binarization. (B) is image data of multiple particles after binarization. [Figure 6] 10 is a graph showing the relationship between the area ratio of white regions in image data of a plurality of particles and the water absorption rate. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure are described below. However, the following embodiments are merely examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content. In the description, the same reference numerals are used for identical elements or elements having the same functions, and redundant description is omitted where appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships based on the orientation of the reference numerals shown in the drawings. The dimensional ratios of each element are not limited to the ratios shown. The numerical range exemplified as "a to b" is a numerical range inclusive of a and b, with a lower limit being a and an upper limit being b. Numerical ranges in which the upper or lower limit of one numerical range is replaced with the upper or lower limit of another numerical range are also included in the present disclosure. When multiple options are exemplified, one of them may be used alone, or multiple options may be used in combination.

[0014] One embodiment of a method for separating particles obtained by crushing concrete blocks includes an image acquisition step of acquiring image data of the particles, an identification step of distinguishing between mortar-rich and aggregate-rich portions using the image data, and a separation step of separating the particles into a plurality of particle groups, including a first particle group and a second particle group having a lower mortar content than the first particle group, based on the results of the identification step. The second particle group has a lower mortar content than the first particle group, and therefore tends to have a higher density, which is a typical quality of recycled aggregate.

[0015] In the present disclosure, the mortar-rich portion and the aggregate-rich portion are relative portions identified using image data, and are not absolute. That is, the mortar-rich portion may have a higher proportion of mortar on the particle surface than the aggregate-rich portion, and the proportion of aggregate components may be higher than the proportion of mortar. The aggregate-rich portion may have a higher proportion of aggregate components on the particle surface than the mortar-rich portion, and the proportion of mortar may be higher than the proportion of aggregate components.

[0016] In the sorting method of this embodiment, where the number of particles to be sorted is n and the number of particle groups obtained by sorting is k, n > k. n / k may be 100 or more, 1000 or more, 10,000 or more, or 100,000 or more. The particles may be obtained, for example, through a crushing step in which concrete blocks are crushed to obtain crushed material, a heating step in which the crushed material is heat-treated, and a grinding step in which the crushed material after the heat treatment is ground to obtain the particles.

[0017] An example of a sorting method may use a recycled aggregate manufacturing facility 100 shown in FIG. 1. The crushing process may be performed using a crusher. Examples of crushers include a jaw crusher that crushes concrete blocks by clamping them between fixed and movable teeth, a hammer crusher that crushes concrete blocks using the impact force of a hammer rotating at high speed, and a centrifugal crusher that uses centrifugal force to scatter concrete blocks at high speed, causing them to collide with existing concrete blocks and concrete fragments in the vicinity, and crushing the concrete blocks using the impact force. Crushing may be performed using one of these devices, or a combination of two or more devices. The particle size of the crushed concrete blocks obtained by the crushing process (hereinafter sometimes simply referred to as "crushed material") may be 40 mm or less.

[0018] In the crushing step, the crushed material may be obtained and then sieved using a first electric sieve to select the crushed material according to its size. Crushed material exceeding a predetermined size may be crushed using, for example, an impact crusher, and then sieved again using the first electric sieve.

[0019] In the heating step, the crushed material may be heated to 80°C or higher, 90°C or higher, or 100°C or higher. The upper limit of the heating temperature may be 350°C. A rotary kiln may be used as a heating device in the heating step. Exhaust gas emitted from at least one of a cement factory and a waste disposal site may be used as the heat source for the heating device. This reduces fuel consumption in the heating device and further reduces the environmental load. The heating time may be 0.1 to 5 hours, 0.2 to 3 hours, or 0.3 to 1 hour. By performing such a heating step, the mortar contained in the crushed material is embrittled by a dehydration reaction, making it easier to peel the mortar from the aggregate components contained in the crushed material.

[0020] The grinding process may be carried out using a device that crushes or pulverizes materials primarily through friction combined with shearing. Examples of such devices include a millstone, a mortar grinder, an edge runner, a roller mill, a planetary grinder, and an agitation tank mill. Specifically, the grinding process may be carried out using a Marmar (product name) manufactured by Kurimoto Iron Works. The grinding process can remove mortar from the crushed material while suppressing the crushing of aggregate components contained in the crushed material. This reduces the mortar content in the crushed material. The grinding process may involve grinding the crushed material using multiple grinders (e.g., a primary grinder and a secondary grinder). The respective aggregate and mortar contents in the crushed material can be adjusted by changing the output (rotation speed) of the grinders. The exhaust gases generated by the rotary kiln and the grinder may be introduced into a dust collector to recover fine powder.

[0021] In this way, pulverized concrete blocks are obtained. The pulverized concrete blocks contain multiple particles, and the content of mortar and aggregate components varies from particle to particle. Because directly measuring the mortar and aggregate components is time-consuming, in this embodiment, image data is used to distinguish between mortar-rich and aggregate-rich portions. Discrimination may be performed on a particle-by-particle basis, a predetermined region-by-region basis in the image data, or an image data-by-image data basis. When distinguishing on a particle-by-particle basis, "first particles" may be distinguished from "second particles" whose surface area ratio of mortar-rich portions is smaller than that of the first particles, based on the area ratio of the mortar-rich portions on the particle surface. In this case, the first particles tend to have a higher mortar content than the second particles, and the second particles tend to have a higher aggregate content and higher density than the first particles. The first particles may contain only mortar or both mortar and aggregate components. The second particles may contain only aggregate components or both aggregate components and mortar. A portion of the surface of the second particles may be covered with mortar.

[0022] In the separation process, a plurality of particles including mortar and aggregate components are separated. The separation process may be performed, for example, according to the flowchart shown in FIG. 2 using a separation device 50 shown in FIGS. 1 and 3. Hereinafter, a description will be given with reference to FIGS. 2 and 3. In the separation process, first, image data of a plurality of particles is acquired (S1). In the separation device 50 shown in FIG. 3, the image data is acquired by a camera 13. A plurality of particles 10 may be transported at a predetermined speed in the direction of arrow A by a conveyor 11. A camera 13 is disposed above the conveyor 11 and captures images of the plurality of particles 10 on the conveyor 11. The camera 13 is not particularly limited as long as it can distinguish the difference in color between the mortar and aggregate components. For example, it may be a normal digital camera or video camera, a camera that can distinguish color differences such as an infrared camera, or a camera that can distinguish between the components contained in mortar and raw aggregate, such as a spectral camera or hyperspectral camera.

[0023] The image data acquired by the camera 13 may be subjected to image processing in the information processing unit 20 (S2). Image processing includes noise removal, contrast enhancement, threshold processing, etc. This allows the multiple particles 10 included in the image data to be distinguished into multiple types based on the shading of their surface colors. For example, as shown in the flowchart of FIG. 2, a threshold is set arbitrarily, and the color of each of the multiple particles 10 included in the image data is determined to be equal to or less than the threshold to distinguish between mortar-rich and aggregate-rich portions (S3, S4, S5). The threshold may be any grayscale value. If the grayscale value of a particle is equal to or less than the threshold, it is distinguished as an aggregate-rich portion (second particle 10B in the case of particle units) (S4), and if it exceeds the threshold, it is distinguished as a mortar-rich portion (first particle 10A in the case of particle units) (S5).

[0024] The identification can be performed by the information processing unit 20 in Fig. 3. The information processing unit 20 can be configured as a normal computer system. As shown in Fig. 3, an example of the hardware configuration of the information processing unit 20 includes at least one processor 72, a memory 74, a storage 76, and an input / output port 78. The storage 76 may store computer software (e.g., analysis software) for realizing each function.

[0025] The information processing unit 20 may be configured to load such computer software onto hardware such as the processor 72 and memory 74, so that the input / output port 78 and the input / output device 82 operate under the control of the processor 72. The storage 76 may be a computer-readable recording medium such as a hard disk, non-volatile semiconductor memory, a magnetic disk, or an optical disk. The storage 76 may store a threshold value or a regression equation between color (for example, the area ratio of the mortar-rich portion or the aggregate-rich portion) and water absorption rate.

[0026] The memory 74 temporarily stores programs and data loaded from the storage 76, calculation results of the processor 72, and the like. The processor 72 may cooperate with the memory 74 to execute programs for performing image processing of image data acquired by the camera 13, deriving grayscale values, determining whether a threshold value is exceeded, and identifying the mortar-rich portion (first particles 10A in the case of particle units) and the aggregate-rich portion (second particles 10B in the case of particle units). The input / output port 78 inputs and outputs electrical signals between the control unit 30 and the input / output device 82, etc., in response to commands from the processor 72. In addition to the identification results, the output device may output the area ratio of the mortar-rich portion to the aggregate-rich portion, and a predicted value of water absorption calculated by a regression equation derived using the area ratio and the actual measured value of water absorption.

[0027] The information processing unit 20 outputs the identification results of the mortar-rich portion and the aggregate-rich portion to the control unit 30. The control unit 30 outputs a control signal to operate the valve 32 based on the input value from the information processing unit 20. The control unit 30 may have, for example, a processor, memory, storage, input / output ports, etc., similar to the information processing unit 20. The control unit 30 only needs to be configured to derive and output a control signal. Note that it is not necessary to configure the information processing unit 20 and the control unit 30 as separate hardware components, and they may be configured as a single piece of hardware.

[0028] When each of the plurality of particles 10 includes both a mortar-rich portion and an aggregate-rich portion, the particles may be separated into particles according to the area ratio of the mortar-rich portion to the aggregate-rich portion in the image data. If the area ratio of the mortar-rich portion is larger, the particles may be separated into a first particle group 12A as first particles 10A, and if the area ratio of the aggregate-rich portion is larger, the particles may be separated into a second particle group 12B as second particles 10B. If the area ratios of the mortar-rich portion and the aggregate-rich portion are equal, the particles may be separated into either the first particle group 12A or the second particle group 12B. In this way, the plurality of particles 10 are separated into the first particle group 12A and the second particle group 12B based on the identification results of the mortar-rich portion and the aggregate-rich portion (S6, S7). For example, in the information processing unit 20 of Fig. 3, when one of the plurality of particles 10 is identified as a second particle 10B, the valve 32 is opened and compressed gas such as compressed air is discharged toward the slit 14 provided downstream of the conveyor 11. The discharged gas passes through the slit 14 from bottom to top, blowing the identified second particle 10B upward. After being blown away by the gas from the slit 14, the second particle 10B falls downward due to gravity.

[0029] On the other hand, if one of the particles 10 is identified as the first particle 10A, the valve 32 is closed, and the first particle 10A, which has passed through the slit 14 from the end of the conveyor 11, falls downward due to gravity. As a result, the first particle 10A and the second particle 10B fall along different paths and are collected in separate containers 15A and 15B. In this manner, the particles 10 are separated into a first particle group 12A containing the first particle 10A and a second particle group 12B containing the second particle 10B (S6, S7). The second particle group 12B thus separated has a lower mortar content and a higher aggregate content than the particles 10 and the first particle group 12A. Therefore, the second particle group 12B is suitable for use in the production of recycled aggregate.

[0030] The separation means is not limited to gas discharge, and separation by gas suction or other means other than wind power may be used. For example, the first particles 10A (first particle group 12A) and the second particles 10B (second particle group 12B) may be separated using a mechanical mechanism that opens and closes a slit 14. The image processing (S2) may include binarization processing. This allows the mortar-rich portion (first particles 10A) and the aggregate-rich portion (second particles 10B) to be distinguished more quickly and accurately.

[0031] 2 and 3, the particles 10 are separated into two types, the first particle group 12A and the second particle group 12B, but this is not limiting. For example, the particles 10 may be separated into three or more types of particle groups by setting multiple thresholds. For example, image data may be used to identify a mortar-rich portion, an intermediate portion, and an aggregate-rich portion, and the particles 10 may be separated into three types of particle groups: a mortar-rich particle group, an aggregate-rich particle group, and an intermediate particle group.

[0032] The separation is not limited to being performed on a particle-by-particle basis. In a modified example, the mortar-rich portion and the aggregate-rich portion may be identified on an image data basis, the area ratio between the two may be derived, and each of the multiple particles included in the image data may be separated into one of the particle groups according to the area ratio. This allows multiple particles 10 to be separated into multiple particle groups more quickly than when the separation and separation are performed on a particle-by-particle basis. In another modified example, the image data may be divided into multiple regions, the mortar-rich portion and the aggregate-rich portion may be identified for each region, the area ratio may be derived, and the multiple particles may be separated into each region according to the area ratio.

[0033] FIG. 4 shows specific examples of the sorting method according to each of the above-described modifications. In FIG. 4(A), four adjacent rectangles represent four image data sets. These image data sets P1, P2, P3, and P4 may be image data obtained by capturing images of multiple particles 10 moving on a conveyor 11 with a camera 13 at predetermined time intervals. Each of the image data sets P1, P2, P3, and P4 contains multiple particles, and the area ratios of the mortar-rich portions (aggregate area ratios) in each set of image data are different from one another. For example, the area ratios of the mortar-rich portions are P1>P3>P2>P4. When these image data sets P1, P2, P3, and P4 are binarized, image data sets IP1, IP2, IP3, and IP4 are obtained. In this case, the threshold value for the binarization process is set between the image data sets P2 and P3.

[0034] The image data IP1 and IP3 (or a plurality of particles contained therein) are identified as a mortar-rich portion and separated into a first particle group 12A, and the image data IP2 and IP4 (or a plurality of particles contained therein) are identified as an aggregate-rich portion and separated into a second particle group 12B. Such separation into particle groups contained in the image data may be performed by switching the conveyor 11's destination at predetermined time intervals. This allows separation into the first particle group 12A containing mortar and the second particle group 12B having a lower mortar content and a higher aggregate content than the first particle group 12A.

[0035] In FIG. 4(B), one rectangle divided into nine regions represents one image data. In this case, the particle groups contained in one image data LP are divided into nine groups. By performing binarization processing for each region (region), image data ILP is obtained. The black region is identified as the aggregate-rich portion, and the particles contained in this region are separated into the second particle group 12B. The white region is identified as the mortar-rich portion, and the particles contained in this region are separated into the first particle group 12A. In this way, by dividing the image data into multiple regions, distinguishing between the mortar-rich portion and the aggregate-rich portion on a region-by-region basis, and separating the particles contained in each region, the accuracy of separating the mortar and aggregate components can be improved compared to when identification and separation are performed on an image data basis. The number of regions is not particularly limited, and any number of regions may be selected.

[0036] Such identification and separation in image data units or region units, or in particle units, can be performed using commercially available devices (such as an automatic sorting device manufactured by Tomra Sorting Co., Ltd. or a small belt-type full-color digital sorter manufactured by Anzai Manufacturing Co., Ltd.) Note that these sorting devices may also be used in combination with a conventional wet specific gravity separator (wet cyclone separator) or the like.

[0037] According to the above-described separation method, the multiple particles obtained by crushing concrete blocks can be quickly and easily separated into a first particle group 12A and a second particle group 12B by utilizing the difference in color between the mortar and aggregate components. In crushed concrete blocks, mortar adheres to the particle surfaces. Therefore, the second particle group 12B, which is separated based on the difference in particle surface color, has a lower mortar content than the first particle group 12A, a sufficiently low water absorption rate, and a sufficiently high density. Therefore, it may be used as a raw material for recycled aggregate, or it may be used as recycled aggregate as is. Therefore, the above-described separation method, which utilizes the unique characteristics of crushed concrete blocks, namely, the location of mortar adhesion and the difference in color between the mortar and aggregate components, can be suitably applied to a method for manufacturing recycled aggregate.

[0038] As shown in FIG. 2, the separated first particle group 12A may be subjected to a heating treatment (S8) and a grinding treatment (S9), after which image data may be acquired again (S1). As shown in FIG. 1, the first particles may be fed back into a rotary kiln and a grinder for heating and grinding. This reduces the mortar content of the first particle group 12A. It is not necessary to perform both the heating and grinding treatments; only the grinding treatment may be performed. The resulting particles may be fed back to the sorting device 50 in FIG. 3 as a group of particles 10 for sorting. This allows a portion of the particles separated into the first particle group 12A to be recovered as the second particle group 12B. This increases the yield of high-quality recycled aggregate obtained from concrete blocks.

[0039] The second particle group 12B separated in the separation step (separation device 50) may also be subjected to at least one of a heating treatment and a grinding treatment, after which image data may be acquired. In this case, the heating treatment and grinding treatment may be performed using equipment other than the rotary kiln and grinder shown in FIG. 1. This prevents the separated second particle group 12B from being mixed with crushed concrete blocks that have not been subjected to the separation step. After acquiring the image data, the image processing (S2), determination of whether the content is below the threshold (S3), classification (S4, S5), and separation (S6, S7) of FIG. 2 are performed again to obtain the second particle group 12B with a higher aggregate content and a lower water absorption rate. Each of these steps (S1 to S7) can be performed using an apparatus similar to the separation device 50 shown in FIG. 3.

[0040] The method for producing recycled aggregate according to one embodiment includes a finishing step for obtaining recycled aggregate from at least a portion of the second particle group 12B obtained by the above-described method for separating a plurality of particles. That is, the method for producing recycled aggregate according to this embodiment includes each step of the above-described separation method. Therefore, the description of the embodiment of the separation method can also be applied to the method for producing recycled aggregate. The method for producing recycled aggregate according to this embodiment can be performed using the recycled aggregate production equipment 100 shown in FIG. 1 and the separation device 50 shown in FIG. 3, following the flowchart shown in FIG. 2.

[0041] In the finishing step, particle size adjustment S10 of the second particle group 12B may be performed as shown in FIG. 2. The particle size adjustment may be performed, for example, using a second electric sieve as shown in FIG. 1. In this case, recycled aggregate can be obtained as undersize (S11). The recycled aggregate may be recycled coarse aggregate. In this manufacturing method, multiple particles 10 obtained by crushing concrete blocks are sorted using the above-mentioned sorting method (sorting device 50), so recycled aggregate can be efficiently produced from concrete blocks. Furthermore, by adjusting the threshold value for identification, quality adjustment of the recycled aggregate, such as water absorption, and yield adjustment can be performed smoothly and simply.

[0042] When producing recycled coarse aggregate, the bone dry density is 2.30 g / cm 3 More than 2.35g / cm 3 More than 2.39g / cm 3 More than 2.40g / cm 3 or more, or 2.41 g / cm 3 The water absorption of the recycled coarse aggregate may be 5.00% by mass or less, 4.70% by mass or less, 4.40% by mass or less, 4.20% by mass or less, 4.00% by mass or less, or 3.90% by mass or less. The bone dry density and water absorption can be measured in accordance with JIS A 1110:2020 "Testing Method for Density and Water Absorption of Coarse Aggregate." The particle size of the recycled coarse aggregate may be 40 mm or less, or may be 5 to 20 mm. The particle size can be adjusted, for example, by changing the mesh size of the second electric sieve in FIG. 1.

[0043] This recycled aggregate manufacturing method uses particle groups separated by a separation method that takes advantage of the unique characteristics of crushed concrete blocks, such as the location of mortar adhesion and the difference in color between the mortar and aggregate components. This allows for efficient and high-yield recovery of recycled aggregate from concrete blocks. Furthermore, by utilizing this separation method, it is possible to reduce the amount of crushed material used in the heating and grinding processes, thereby suppressing the grinding of aggregate components during these processes. This allows for an increased yield of high-quality recycled coarse aggregate.

[0044] A particle quality evaluation method according to one embodiment includes the steps of acquiring image data of a plurality of particles, distinguishing between a mortar-rich portion and an aggregate-rich portion using the image data, and deriving the area ratio of at least one of the mortar-rich portion and the aggregate-rich portion in the image data based on the results of the distinction. Acquiring the image data and distinguishing between the mortar-rich portion and the aggregate-rich portion may be performed using steps S1 to S5 in the flowchart of FIG. 2 and the camera 13, information processing unit 20, and input / output device 82 in the sorting apparatus 50 of FIG. 3, similar to the particle sorting method described above. Therefore, the same explanation as for the method for sorting a plurality of particles applies to the quality evaluation method of this embodiment.

[0045] In the image data captured by the camera 13, the area of ​​the mortar-rich portion can be regarded as the area of ​​the portion below a predetermined threshold. In the image data, the area of ​​the aggregate-rich portion can be regarded as the area of ​​the portion above a predetermined threshold. The image data may be binarized to determine the area of ​​the mortar-rich portion and the area of ​​the aggregate-rich portion. From each area thus determined, the area ratio of the mortar-rich portion to the total area of ​​the mortar-rich portion and the aggregate-rich portion can be derived. Furthermore, the area ratio of the aggregate-rich portion to the total area of ​​the mortar-rich portion and the aggregate-rich portion can be derived. These calculations may be performed by the information processing unit 20. This allows the quality of multiple particles to be evaluated, such as the mortar content, aggregate component content, and water absorption rate. The evaluation may be performed by performing regression analysis of the measured values ​​of the water absorption rate or each content rate of multiple particles and the area ratio of the mortar-rich portion or the aggregate-rich portion to create a calibration curve (regression equation), and then predicting the water absorption rate and each content rate using the calibration curve.

[0046] There is a good correlation between the area ratio of the mortar-rich or aggregate-rich portion of multiple particles obtained by crushing concrete blocks and the water absorption rate. Therefore, the information processing unit 20 may be used to predict the water absorption rate of multiple particles contained in image data based on the area ratio of the mortar-rich or aggregate-rich portion. While the water absorption rate measurement method conforming to JIS A 1110:2020 described above requires several days to obtain measurement results, the quality evaluation method of this embodiment allows the water absorption rate to be predicted easily and quickly. Moreover, the predicted water absorption rate value derived in this manner has sufficiently high accuracy.

[0047] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the particle separation method and the recycled aggregate production method may be performed using equipment other than the recycled aggregate production equipment 100 shown in Figure 1 and the separation device 50 shown in Figure 3. Furthermore, it is not essential to use a rotary kiln as the heating device.

[0048] The present disclosure includes the following embodiments [1] to

[12] . [1] A method for separating multiple particles obtained by crushing concrete blocks, comprising: acquiring image data of the plurality of particles; using the image data to distinguish between a mortar-rich portion and an aggregate-rich portion; and a step of sorting the plurality of particles into a plurality of particle groups including a first particle group and a second particle group having a lower mortar content than the first particle group based on the results of the identification. [2] A particle separation method according to [1], comprising a step of performing a binarization process on the image data, and using the image data after the binarization process to distinguish between the mortar-rich portion and the aggregate-rich portion. [3] A method for separating particles according to [1] or [2], which comprises a step of performing at least one of a heating treatment and a grinding treatment on the crushed concrete blocks to obtain the plurality of particles before acquiring the image data. [4] The method for separating particles according to any one of [1] to [3], which comprises at least one of a heat treatment and a grinding treatment of the first particle group. [5] The method for separating particles according to any one of [1] to [4], wherein the step of separating into a plurality of particle groups includes separating the plurality of particles using wind power. [6] The particle sorting method according to any one of [1] to [5], wherein at least one of the first particle group and the second particle group is subjected to one or both of a heating treatment and a grinding treatment to obtain particles, which are used as the plurality of particles, and the step of acquiring the image data, the step of identifying, and the step of sorting are carried out again. [7] A method for producing recycled aggregate, comprising the step of obtaining recycled aggregate from at least a part of the second particle group separated by the separation method according to any one of [1] to [6] above. [8] The method for producing recycled aggregate according to [7], wherein the step of obtaining the recycled aggregate includes sieving the second particle group. [9] A method for evaluating the quality of a plurality of particles obtained by crushing concrete blocks, comprising: acquiring image data of the plurality of particles; a step of identifying a mortar-rich portion and an aggregate-rich portion using the image data, and deriving an area ratio of at least one of the mortar-rich portion and the aggregate-rich portion in the image data based on the identification result.

[10] The quality evaluation method according to [9], which predicts the water absorption rate of the plurality of particles based on the area ratio.

[11] A quality evaluation method according to [9] or

[10] , comprising a step of performing a binarization process on the image data, and using the image data after the binarization process to identify the mortar-rich portion and the aggregate-rich portion.

[12] A quality evaluation method described in any one of [9] to

[11] , which includes a step of performing at least one of a heating treatment and a grinding treatment on the crushed concrete block material to obtain the plurality of particles before acquiring the image. [Example]

[0049] The present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0050] (Comparative Example 1) Concrete waste was crushed to prepare multiple particles with particle sizes of approximately 5 to 20 mm. Images of the prepared particles were captured using a camera (product name: iPhone 12 ("iPhone" is a registered trademark of Apple Inc.)). Image data was then binarized using Image J. The color image was converted to 8-bit (256-level grayscale) data, and the pixel values ​​at which the mortar area was distinguished as white were visually selected while comparing the color and grayscale images. Image J was used to calculate the area ratio of the white area (mortar-rich area) from the binarized image data. The results are shown in Table 1. The water absorption of the multiple particles was also measured in accordance with JIS A 1110:2020, "Test Method for Density and Water Absorption of Coarse Aggregate." The measurement results are shown in Table 1.

[0051] Examples 1 to 4 The multiple particles prepared in Comparative Example 1 were milled using a ball mill. Reinforcing bars were used as the medium. The medium-sample ratio and rotation speed of the ball mill were as shown in Table 1. The medium-sample ratio in Table 1 refers to the ratio of the mass of the multiple particles to the mass of the medium. As in Comparative Example 1, image data of the multiple particles obtained in each Example was acquired and binarized to determine the area ratio of the white region (mortar-rich portion). The results are shown in Table 1. In addition, the water absorption of the multiple particles in each Example was measured in accordance with JIS A 1110:2020 "Test method for density and water absorption of coarse aggregate." The measurement results are shown in Table 1.

[0052] Figure 5 shows image data of multiple particles from Example 1. (A) is the image data before binarization, and (B) is the image data after binarization. It was confirmed that binarization made the color differences clearer, making it easier to distinguish between mortar-rich and aggregate-rich areas.

[0053] (Comparative Example 2) A plurality of particles having particle sizes of approximately 5 to 20 mm were prepared by crushing waste concrete chunks different from those used in Comparative Example 1. As in Comparative Example 1, image data of the prepared plurality of particles was acquired and binarized to calculate the area ratio of the white region (mortar-rich portion). The results are shown in Table 1. In addition, the water absorption of the plurality of particles was measured in accordance with JIS A 1110:2020 "Testing method for density and water absorption of coarse aggregate." The measurement results are shown in Table 1.

[0054] [Table 1]

[0055] Figure 6 shows the relationship between the area ratio of the white region in Table 1 and the water absorption rate. It was confirmed that the larger the area of ​​the white region, the higher the water absorption rate, i.e., the higher the mortar content. This confirmed that there is a good correlation between the mortar content in multiple particles and the area ratio of the white region (mortar-rich part). These results show that by identifying and sorting the multiple particles obtained by crushing concrete blocks based on their color, it is possible to obtain particles with a low mortar content and a high aggregate content. [Explanation of symbols]

[0056] 10...multiple particles, 10A...first particle, 10B...second particle, 11...conveyor, 13...camera, 12A...first particle group, 12B...second particle group, 14...slit, 15A, 15B...container, 20...information processing unit, 30...control unit, 32...valve, 50...sorting device, 72...processor, 74...memory, 76...storage, 78...input / output port, 82...input / output device, 100...recycled aggregate manufacturing equipment.

Claims

1. A method for separating a plurality of particles obtained by crushing concrete blocks, comprising: acquiring image data of the plurality of particles; using the image data to distinguish between a mortar-rich portion and an aggregate-rich portion; and a step of sorting the plurality of particles into a plurality of particle groups including a first particle group and a second particle group having a lower mortar content than the first particle group based on a result of the identification.

2. 2. The particle separation method according to claim 1, further comprising a step of binarizing the image data, and using the binarized image data to distinguish between the mortar-rich portion and the aggregate-rich portion.

3. 3. The particle separation method according to claim 1, further comprising the step of subjecting the crushed concrete blocks to at least one of a heat treatment and a grinding treatment to obtain the plurality of particles before acquiring the image data.

4. The method for separating particles according to claim 1 or 2, comprising a step including at least one of a heat treatment and a grinding treatment of the first particle group.

5. The method for separating particles according to claim 1 or 2, wherein the step of separating the particles into a plurality of particle groups includes separating the plurality of particles using wind power.

6. 3. The particle sorting method according to claim 1, wherein at least one of the first particle group and the second particle group is subjected to one or both of a heating treatment and a grinding treatment to obtain particles, which are used as the plurality of particles, and the step of acquiring the image data, the step of identifying, and the step of sorting are performed again.

7. A method for producing recycled aggregate, comprising the step of obtaining recycled aggregate from at least a part of the second particle group separated by the separation method according to claim 1 or 2.

8. The method for producing recycled aggregate according to claim 7 , wherein the step of obtaining the recycled aggregate includes sieving the second particle group.

9. A method for evaluating the quality of a plurality of particles obtained by crushing concrete blocks, comprising: acquiring image data of the plurality of particles; a step of identifying a mortar-rich portion and an aggregate-rich portion using the image data, and deriving an area ratio of at least one of the mortar-rich portion and the aggregate-rich portion in the image data based on the identification result.

10. The quality evaluation method according to claim 9 , further comprising predicting the water absorption rate of the plurality of particles based on the area ratio.

Images