Method for estimating the quality of live masonry

Abstract

To provide a method capable of estimating the quality of ready-mixed concrete easily and with high accuracy.SOLUTION: A quality estimation method of ready-mixed concrete includes: process of using a plurality of standard ready-mixed concretes and photographic means capable of identifying wavelengths of 700 nm or more, photographing the surface of each of the plurality of standard ready-mixed concretes, and acquiring data regarding the light with wavelengths of 700 nm or more from the photographed images: process of using a ready-mixed concrete subject to quality estimation and the photographic means, photographing the surface of the ready-mixed concrete subject to quality estimation, and acquiring data regarding the light with wavelengths of 700 nm or more from the photographed images of the ready-mixed concrete subject to quality estimation; and process of obtaining estimated values of data regarding the quality of ready-mixed concrete subject to quality estimation based on the above data regarding the light for standard ready-mixed concretes and the above data regarding the light for the ready-mixed concrete subject to quality estimation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for estimating the quality of fresh concrete.

Background Art

[0002] Fresh concrete is manufactured by kneading each material in a mixer for a predetermined time based on a mixture adjusted according to the quality of the target fresh concrete. On the other hand, even when the mixture and kneading time are the same, the quality of the manufactured fresh concrete varies due to variations in the physical properties and storage conditions of fresh concrete materials such as the surface water content rate of aggregates, or the outside air temperature during manufacturing. In order to actually measure and confirm the quality of fresh concrete, it takes time and labor, and depending on the skill of the person performing the actual measurement, variations may occur in the measurement results. As a method for evaluating the segregation of concrete materials, Patent Document 1 describes a method for evaluating the segregation state of high-flow concrete by measuring the color difference between the surfaces of non-segregated fresh normal concrete and fresh high-flow concrete using the same materials.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a result of diligent research to solve the above problems, the inventors have found that the above objectives can be achieved by a method that includes the steps of: photographing the surface of a reference ready-mixed concrete using multiple reference ready-mixed concretes and an imaging means, and obtaining data on light with wavelengths of 700 nm or longer from the obtained image; photographing the surface of ready-mixed concrete to be used for quality estimation, and obtaining data on light with wavelengths of 700 nm or longer from the obtained image; and obtaining an estimated value of quality data for ready-mixed concrete to be estimated based on the light data of the reference ready-mixed concrete and the light data of the ready-mixed concrete to be used for quality estimation, and have completed the present invention. In other words, the present invention provides the following [1] to [6]. [1] A method for estimating the quality of ready-mixed concrete, comprising: a first imaging step of imaging the surface of each of the multiple reference ready-mixed concretes that serve as a standard for estimating the quality of ready-mixed concrete, using imaging means capable of identifying wavelengths of 700 nm or longer, and obtaining data relating to light with wavelengths of 700 nm or longer from the obtained images for each of the multiple reference ready-mixed concretes; a second imaging step of imaging the surface of the ready-mixed concrete to be the subject of quality estimation, using the imaging means, and obtaining data relating to light with wavelengths of 700 nm or longer of the ready-mixed concrete to be the subject of quality estimation from the obtained images; and an estimation step of obtaining an estimated value of data relating to the quality of the ready-mixed concrete to be the subject of quality estimation based on the data relating to light with wavelengths of 700 nm or longer of the reference ready-mixed concrete and the data relating to light with wavelengths of 700 nm or longer of the ready-mixed concrete to be the subject of quality estimation.

[0006] [2] The method for estimating the quality of ready-mixed concrete according to [1], wherein a light source is used in each of the first and second imaging steps, and in the first imaging step, the light source used to irradiate the surface of the standard ready-mixed concrete to be photographed is adjusted so that the average reflectance of the resulting image is 20% or more, and in the second imaging step, the surface of the ready-mixed concrete to be estimated is photographed using the light source whose light intensity was adjusted in the first imaging step. [3] The method for estimating the quality of ready-mixed concrete according to [1] or [2] above, wherein the data relating to the quality of ready-mixed concrete is the unit water content. [4] The method for estimating the quality of ready-mixed concrete according to [3], wherein in each of the first and second photography steps described above, the surface of the standard ready-mixed concrete or the ready-mixed concrete subject to quality estimation is photographed at an arbitrary time within the period from immediately after mixing until 1 minute has elapsed.

[0007] [5] A method for estimating the quality of ready-mixed concrete according to any one of [1] to [4] above, comprising a step provided between the first imaging step and the estimation step, wherein regression analysis is performed with data relating to light of the standard ready-mixed concrete with a wavelength of 700 nm or more as the independent variable and data relating to the quality of the standard ready-mixed concrete as the dependent variable, and the regression equation, which is a relationship between the data relating to light of the standard ready-mixed concrete with a wavelength of 700 nm or more and the data relating to the quality of the standard ready-mixed concrete, is used as an estimation equation for estimating the quality of ready-mixed concrete, and in the estimation step, an estimated value of the data relating to the quality of ready-mixed concrete that is the subject of quality estimation is obtained using the data relating to light of the ready-mixed concrete with a wavelength of 700 nm or more and the estimation equation. [6] The method for estimating the quality of ready-mixed concrete according to [5], wherein the data relating to light with a wavelength of 700 nm or more is absorbance data and includes absorbance at least one wavelength selected from the wavelength range of 800 to 2,000 nm. [Effects of the Invention]

[0008] According to the concrete quality estimation method of the present invention, the quality of ready-mixed concrete can be estimated simply and with high accuracy. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the relationship between the measured and predicted unit water volume in Example 1, represented by a straight line, and plots the measured and predicted unit water volume in Example 1. [Modes for carrying out the invention]

[0010] The present invention provides a method for estimating the quality of ready-mixed concrete, comprising: a first imaging step of using a plurality of standard ready-mixed concrete samples that serve as a standard for estimating the quality of ready-mixed concrete, and imaging means capable of identifying wavelengths of 700 nm or longer to image the surface of each of the plurality of standard ready-mixed concrete samples, and obtaining data relating to light with wavelengths of 700 nm or longer from the obtained images; a second imaging step of using the imaging means to image the surface of the ready-mixed concrete sample that is the subject of quality estimation, and obtaining data relating to light with wavelengths of 700 nm or longer of the ready-mixed concrete sample that is the subject of quality estimation from the obtained images; and an estimation step of obtaining an estimated value of data relating to the quality of the ready-mixed concrete sample that is the subject of quality estimation based on the data relating to light with wavelengths of 700 nm or longer of the standard ready-mixed concrete samples and the data relating to light with wavelengths of 700 nm or longer of the ready-mixed concrete sample that is the subject of quality estimation. The following explains each step in detail.

[0011] [First shooting process] This process involves photographing the surface of each of the multiple standard ready-mixed concrete samples, which serve as a standard for estimating the quality of ready-mixed concrete, using imaging equipment capable of identifying wavelengths of 700 nm or longer. From the resulting images, data related to light with wavelengths of 700 nm or longer is obtained for each of the multiple standard ready-mixed concrete samples. Standard ready-mixed concrete can be any type of ready-mixed concrete, and there are no particular restrictions on its materials or mix ratios. However, from the standpoint of achieving higher accuracy in estimation, ready-mixed concrete made from the same materials as the ready-mixed concrete being estimated is preferable. From the viewpoint of being able to estimate the quality of ready-mixed concrete with higher accuracy, the number of standard ready-mixed concrete samples should be 2 or more, preferably 5 or more, more preferably 10 or more, and particularly preferably 15 or more. Furthermore, from the viewpoint of reducing the labor required to produce the concrete for creating the estimation formula, the above number should be 30 or less, more preferably 25 or less. Furthermore, it is preferable that each of the multiple standard ready-mixed concrete samples uses the same materials, but has different mix designs and manufacturing conditions.

[0012] Examples of imaging methods capable of distinguishing wavelengths of 700 nm or higher include multi-wavelength spectroscopic cameras such as multispectral cameras and hyperspectral cameras. Among these, hyperspectral cameras are preferred from the viewpoint of obtaining data on light with wavelengths of 700 nm or higher with higher accuracy. Photographs of standard ready-mixed concrete are taken, for example, of the following: (1) ready-mixed concrete in a mixer (hereinafter also simply referred to as "mixer") while the materials are being mixed; (2) ready-mixed concrete after mixing is complete in the mixer (after the mixing of each material is complete); (3) ready-mixed concrete that has been put from the mixer into the hopper after mixing; (4) ready-mixed concrete being stirred in the drum of a truck agitator; (5) ready-mixed concrete used in various tests such as slump tests, before or after the test; and (6) the surface of ready-mixed concrete flowing down the chute of an agitator truck. Furthermore, it is preferable that each of the multiple standard ready-mixed concrete samples be photographed at an arbitrarily determined time, from the viewpoint of being able to estimate the quality of the ready-mixed concrete with greater accuracy. The arbitrarily determined time will vary depending on the quality of the ready-mixed concrete to be estimated, the mix design of the ready-mixed concrete, the manufacturing conditions of the ready-mixed concrete, etc., but for example, it may be an arbitrarily determined time within 5 minutes immediately after the completion of mixing of the ready-mixed concrete (for example, 30 seconds after the completion of mixing of the ready-mixed concrete). Furthermore, two or more photographs may be taken of a single standard concrete sample to obtain two or more images.

[0013] By capturing images using imaging equipment, data related to light with wavelengths of 700 nm or greater can be obtained for each of the multiple standard ready-mixed concrete samples. The above image may be the captured image (hereinafter also referred to as the "captured image") as is, or it may be an image obtained by cropping a portion of the captured image (for example, an image consisting only of the area in which the surface of the fresh concrete is reflected). Furthermore, multiple images may be cropped from the captured images in order to increase the number of independent variables used in creating the estimation formula (described later) and to obtain an estimation formula that can estimate the quality of ready-mixed concrete with higher accuracy. Data relating to light refers to data concerning the properties of light (reflected light). Examples of light properties include absorbance, reflectance, and radiance. Among these, absorbance is preferred from the viewpoint of ease of acquisition. These may be used individually or in combination of two or more types. Data relating to light with wavelengths of 700 nm or higher refers to data relating to light at a specific wavelength arbitrarily defined, which is 700 nm or higher. This data relating to light includes a numerical value (e.g., absorbance) relating to at least one characteristic of the light obtained from the above image. In addition, numerical values related to the characteristics of light can be obtained for each pixel constituting the above image. Therefore, the average value of the numerical values related to the characteristics of light at a specific wavelength obtained from all the pixels constituting the above image may be used as the numerical value related to the characteristics of light included in the data related to the above light. When a plurality of images are cut out from the photographed image, data related to the above light can be obtained from each of the cut-out images.

[0014] The wavelengths at which data related to light are obtained in the first photographing step and the second photographing step may be those selected by performing correlation analysis with the numerical value related to the characteristics of light (for example, absorbance) at a specific wavelength as an independent variable and the quality of fresh concrete (for example, the measured value of the unit water content) as a dependent variable, and selecting wavelengths with a correlation coefficient of 0.6 or more (preferably 0.7 or more). The wavelengths with a correlation coefficient of 0.6 or more can be determined as the wavelengths indicating the peaks of the characteristics of light (for example, absorbance) that have a large correlation with the quality of fresh concrete. Fresh concrete is a composite material, and as the hydration reaction of cement progresses over time, the wavelengths at which numerical values related to the characteristics of light (for example, absorbance) that have a large correlation with the quality of fresh concrete (for example, unit water content) can be obtained may vary depending on the type of fresh concrete, the timing of photographing, etc. Therefore, by using the data related to light at the wavelengths with a large correlation coefficient, the quality of fresh concrete can be estimated with higher accuracy. In addition, from the viewpoint of estimating the quality of fresh concrete with higher accuracy, the number of wavelengths to be selected is preferably 3 or more, more preferably 4 or more, and particularly preferably 5 or more.

[0015] For example, from the viewpoint of estimating the quality of fresh concrete with higher accuracy, the data related to light with wavelengths of 700 nm or more preferably includes the numerical values related to the characteristics of light of at least one wavelength (preferably 2 to 30, more preferably 5 to 25, and particularly preferably 10 to 20) selected from the wavelength range of 800 to 2,000 nm. In particular, from the viewpoint of estimating the quality of ready-mixed concrete with higher accuracy, the above-mentioned data on light preferably includes absorbance at wavelengths selected from the wavelength range of 1,400 to 1,500 nm, and more preferably includes numerical values ​​(e.g., absorbance) relating to the characteristics of light at wavelengths selected from the wavelength ranges of 940 to 990 nm (even more preferably 950 to 980 nm), 1,290 to 1,340 nm (even more preferably 1,300 to 1,330 nm), 1,400 to 1,460 nm (even more preferably 1,410 to 1,450 nm), 1,500 to 1,550 nm (even more preferably 1,510 to 1,540 nm), and 1,600 to 1,700 nm (even more preferably 1,610 to 1,690 nm).

[0016] [Second shooting process] This process involves photographing the surface of the ready-mixed concrete to be subject to quality estimation using imaging means capable of identifying wavelengths of 700 nm or longer (the imaging means used in the first imaging process), and obtaining data on light with wavelengths of 700 nm or longer from the obtained image. The ready-mixed concrete that is the subject of this invention is various types of ready-mixed concrete, and its materials and mixing ratios are not particularly limited. Furthermore, the shooting method, shooting conditions for the surface of the ready-mix concrete, and the above-mentioned data regarding light are the same as in the first shooting process.

[0017] [Estimation process] This process involves obtaining an estimated value of quality data for the ready-mixed concrete subject to quality estimation, based on the data on light wavelengths of 700 nm or higher obtained in the first imaging process for the standard ready-mixed concrete and the data on light wavelengths of 700 nm or higher obtained in the second imaging process for the ready-mixed concrete subject to quality estimation. The data used to estimate the quality of ready-mixed concrete is not limited to any data relating to the quality of ready-mixed concrete that can be expressed numerically, but examples include the unit water content. Examples of methods for obtaining estimated values ​​of data regarding the quality of ready-mixed concrete that is the subject of quality estimation include: (i) creating an estimation formula for estimating the quality of ready-mixed concrete using data on light with wavelengths of 700 nm or more for standard ready-mixed concrete, and then using this estimation formula and data on light with wavelengths of 700 nm or more for the ready-mixed concrete to be estimated to obtain estimated values ​​of data regarding the quality of the ready-mixed concrete to be estimated; and (ii) creating a prediction model for estimating the quality of ready-mixed concrete using machine learning (e.g., machine learning using a neural network) with data on light with wavelengths of 700 nm or more for standard ready-mixed concrete, and then using this prediction model and data on light with wavelengths of 700 nm or more for the ready-mixed concrete to be estimated to obtain estimated values ​​of data regarding the quality of the ready-mixed concrete to be estimated.

[0018] The following describes in detail an example of a method for estimating the quality of ready-mixed concrete, which involves creating an estimation formula for estimating the quality of ready-mixed concrete in the estimation formula creation process, and then using the above estimation formula to obtain estimated values ​​of data related to the quality of ready-mixed concrete that is the subject of quality estimation (method (i) above). [Estimation formula creation process] This step is a step provided between the first imaging step and the estimation step described above, and involves performing regression analysis with the data on light with wavelengths of 700 nm or more obtained from the standard ready-mixed concrete in the first imaging step as the independent variable and the data on the quality of the standard ready-mixed concrete as the dependent variable, and using the regression equation, which is the relationship between the data on light with wavelengths of 700 nm or more of the standard ready-mixed concrete and the data on the quality of the standard ready-mixed concrete, as the estimation equation for estimating the quality of the ready-mixed concrete. This process may be performed before the second shooting process or after the second shooting process.

[0019] The data relating to the quality of ready-mixed concrete used as a standard is not particularly limited as long as it relates to the quality of ready-mixed concrete and can be expressed as a numerical value, but examples include the unit water content. The number of data combinations consisting of independent and dependent variables used in regression analysis is 2 or more, preferably 5 or more, more preferably 10 or more, and particularly preferably 15 or more. Furthermore, from the viewpoint of reducing the effort required for regression analysis, the above number is preferably 30 or less, and more preferably 25 or less. After obtaining an estimation formula in the estimation formula creation process, in the estimation process, an estimated value of the quality data of the ready-mixed concrete to be estimated can be obtained using the estimation formula obtained based on the data on light with wavelengths of 700 nm or more for the ready-mixed concrete to be subject to quality estimation in the estimation process, and the quality of the ready-mixed concrete to be subject to quality estimation can be estimated based on the obtained estimated value.

[0020] When photographing ready-mix concrete in a dark place such as inside a mixer, from the viewpoint of estimating the quality of the ready-mix concrete with higher accuracy, the surface of the ready-mix concrete being photographed may be illuminated with light using a light source (for example, a halogen lamp) in each of the first and second photographing steps described above. The above light source is preferably adjusted (for example, by adjusting the light intensity, position, etc.) so that the average reflectance of the image obtained in the first shooting step is 20% or more, more preferably 40% or more, and particularly preferably 60% or more. The upper limit of the average reflectance is preferably 90%, more preferably 80%. The reflectance can be obtained for each pixel that makes up the image obtained in the first imaging process. The average reflectance is the average of the reflectances obtained from all pixels that make up the image.

[0021] Furthermore, reflectance can be obtained for each wavelength of the pixels that make up the image described above. For this reason, the reflectance at a specific wavelength obtained from the above pixels (usually the same wavelength from which the numerical values ​​of the optical properties included in the light-related data described above were obtained) may be used as the reflectance obtained from the pixels that make up the image. When using reflectances at multiple wavelengths, the average value of the reflectances obtained from multiple wavelengths may be used as the reflectance obtained from the pixels that make up the image. Furthermore, if a light source is used in the first shooting process, then in the second shooting process, the surface of the ready-mixed concrete, which is the subject of quality estimation, is photographed using a light source whose light intensity has been adjusted in the first shooting process (under the same conditions as the first shooting process).

[0022] In this invention, various conditions such as the timing of photography and the wavelength used to obtain light-related data (numerical values ​​related to the characteristics of light) are appropriately adjusted according to the quality of the ready-mixed concrete. For example, if the data relating to the quality of ready-mixed concrete is the unit water content, it is preferable to photograph the surface of the standard ready-mixed concrete or the ready-mixed concrete subject to quality estimation during the first and second photography steps described above, within a time period from immediately after the ready-mixed concrete is mixed until 1 minute has elapsed (preferably within a time period from immediately after the ready-mixed concrete is mixed until 30 seconds have elapsed, more preferably within a time period from immediately after the ready-mixed concrete is mixed until 10 seconds have elapsed, and at an arbitrarily determined time). By taking photographs within the above time frame, it is possible to obtain a more accurate estimate of the quality of the ready-mixed concrete. The ready-mix concrete can be photographed at any arbitrarily determined time, and the ready-mix concrete can be photographed inside the mixer, or the ready-mix concrete can be photographed as it is being poured from the mixer into the hopper. [Examples]

[0023] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement; ordinary Portland cement, density: 3.16 g / cm³ 3 (2) Fine aggregate; mountain sand, surface dry density: 2.57g / cm 3 (3) Coarse aggregate; crushed stone, surface dry density: 2.64 g / cm³ 3 (4) AE water-reducing agents; lignin sulfonic acid-based AE water-reducing agents (5) Air volume regulators; rosin-based air volume regulators (6) Water; tap water

[0024] [Example 1] The above materials were mixed using a mixer according to the proportions shown in Table 1 to prepare ready-mix concrete 1 to 17. Immediately after mixing, the surface of each fresh concrete sample was photographed using a hyperspectral camera capable of distinguishing wavelengths from 900 to 1700 nm. From the captured images, only the dark areas such as the boundary between the mixer components and the fresh concrete, and the areas where the aforementioned components are not visible, and where only the fresh concrete is visible (approximately 300 x 300 mm), were cropped. Furthermore, the cropped area was divided into eight equal parts, resulting in eight images consisting of 55 × 95 pixel regions (resolution approximately 1.2 × 1.2 mm / pixel). Of these eight images, the absorbance data obtained from six images was used as absorbance data for creating the estimation formula, and the absorbance data obtained from the remaining two images was used as absorbance data for verification. Furthermore, when taking the images, a halogen lamp was used as the light source to illuminate the mixer, and the settings were adjusted so that the average reflectance of the surface of the ready-mix concrete in the images obtained for absorbance data was 40% or higher.

[0025] [Table 1]

[0026] For each of the 102 images obtained from the images of ready-mix concrete 1 to 17, the average absorbance at wavelengths of 967 nm, 1,317 nm, 1,432 nm, 1,527 nm, 1,632 nm, 1,647 nm, and 1,687 nm was measured (the absorbance at each wavelength was measured for each pixel constituting the image, and the average value was calculated from the absorbance of all pixels). The absorbance at these seven wavelengths was used as the absorbance data. The above wavelengths were all selected based on a correlation analysis in which the absorbance of ready-mixed concrete 1 to 17 at the above wavelengths was the independent variable and the unit water content of the ready-mixed concrete was the dependent variable, resulting in a correlation coefficient of 0.6 or higher. Furthermore, the measured unit water content of ready-mixed concrete samples 1-17 was calculated by first measuring the air content of the ready-mixed concrete using an air meter, and then correcting for the volume component of the concrete. Data for creating an estimation formula, consisting of absorbance data at seven wavelengths and measured unit water content, was obtained from each of the 102 images. Multiple regression analysis was performed using the absorbance at each of the above wavelengths as the independent variable and the unit water content of the obtained ready-mixed concrete as the dependent variable, and the following estimation equation (1) was obtained. W=-590.3X1-3323.2X2-234.1X3-9616.6X4+3113.5X5+2551.4X6+2370.9X7+284.9 (1) (In the above estimation formula (1), W is the estimated value of the unit water volume, X1 is the absorbance at a wavelength of 967 nm, X2 is the absorbance at a wavelength of 1,317 nm, X3 is the absorbance at a wavelength of 1,432 nm, X4 is the absorbance at a wavelength of 1,527 nm, X5 is the absorbance at a wavelength of 1,632 nm, X6 is the absorbance at a wavelength of 1,647 nm, and X7 is the absorbance at a wavelength of 1,687 nm.)

[0027] Using 34 absorbance data points for verification and the estimation formula described above, 34 estimated values ​​for the unit water volume were obtained. Figure 1 shows the following relational equation (a) which illustrates the relationship between the measured and estimated values ​​of the unit water volume. y1 = 0.672x1 + 55.695 ... (a) (In the above relational equation (a), x1 is the measured value of the unit water volume, and y1 is the estimated value of the unit water volume.) Note that the coefficient of determination (R) of relation (a) 2 The value was 0.8001. Figure 1 shows that the estimation formula of the present invention allows for the estimation of the unit water volume with high accuracy.

Claims

1. A method for estimating the quality of ready-mixed concrete, A first imaging step involves photographing the surface of each of the multiple standard ready-mixed concrete samples, which serve as a standard for estimating the quality of ready-mixed concrete, using imaging means capable of identifying wavelengths of 700 nm or longer, and obtaining data on light with wavelengths of 700 nm or longer from the obtained images for each of the multiple standard ready-mixed concrete samples. A regression analysis is performed using the data on light wavelengths of 700 nm or more for the standard ready-mixed concrete as the independent variable, and the data on the quality of the standard ready-mixed concrete as the dependent variable. The regression equation, which is the relationship between the data on light wavelengths of 700 nm or more for the standard ready-mixed concrete and the data on the quality of the standard ready-mixed concrete, is used as an estimation equation for estimating the quality of the ready-mixed concrete. A second imaging step involves photographing the surface of the ready-mixed concrete subject to quality estimation using the above-mentioned imaging means, and obtaining data on light wavelengths of 700 nm or longer from the obtained image of the ready-mixed concrete subject to quality estimation. This includes an estimation step to obtain an estimated value of the quality data of the ready-mixed concrete subject to quality estimation, based on the above-mentioned data on light with wavelengths of 700 nm or more for the standard ready-mixed concrete and the above-mentioned data on light with wavelengths of 700 nm or more for the ready-mixed concrete subject to quality estimation. The above estimation formula creation process is provided between the first shooting process and the estimation process. The above data relating to light with wavelengths of 700 nm or more is absorbance data and includes absorbance at least one wavelength selected from the wavelength range of 800 to 2,000 nm. A method for estimating the quality of ready-mixed concrete, characterized in that, in the estimation step described above, an estimated value of the data relating to the quality of ready-mixed concrete subject to quality estimation is obtained by using the data relating to light with a wavelength of 700 nm or more of the ready-mixed concrete subject to quality estimation and the estimation formula described above.

2. In each of the above-mentioned first shooting process and the above-mentioned second shooting process, a light source is used. In the first photographic process described above, the light source that illuminates the surface of the reference concrete being photographed is adjusted so that the average reflectance of the resulting image is 20% or more. The method for estimating the quality of ready-mixed concrete according to claim 1, wherein in the second shooting step described above, the surface of the ready-mixed concrete subject to quality estimation is photographed using the light source whose light intensity was adjusted in the first shooting step described above.

3. The method for estimating the quality of ready-mixed concrete according to claim 1 or 2, wherein the data relating to the quality of the ready-mixed concrete is the unit water content.

4. The method for estimating the quality of ready-mixed concrete according to claim 3, wherein in each of the first and second photography steps described above, the surface of the standard ready-mixed concrete or the ready-mixed concrete subject to quality estimation is photographed at an arbitrarily determined time within the period from immediately after mixing until one minute has elapsed.

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