A method for measuring the slump expansion of concrete

Abstract

The present invention relates to a method for measuring the slump expansion of concrete, comprising the following steps: S1: making a concrete slump expansion model on a pre-set measuring device, collecting a concrete slump expansion image, wherein the image includes the measuring device and the concrete slump expansion model; S2: performing contour recognition on the concrete slump expansion image, generating and correcting the contour image; S3: determining the proportional relationship between the contour of the concrete slump expansion model and the contour of the measuring device according to the known actual size of the measuring device and the corrected contour image, and calculating the slump expansion of concrete according to the proportional relationship and the actual size of the measuring device. Compared with the prior art, the present invention can accurately and efficiently measure the slump expansion of concrete.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, in particular to a method for measuring the slump spread of concrete. Background Art

[0002] Slump expansion is one of the most important indicators of concrete quality. It comprehensively represents the fluidity, stability, and ability to pass through steel bar gaps of the mixture.

[0003] The method for obtaining the slump expansion is to load the concrete mixture into a standard cone slump cone according to the prescribed method, and after it is filled and leveled, lift the cone vertically upward and move it aside. It should be noted that the height of the standard cone slump cone is generally 30cm. The concrete mixture will slump and expand due to its own weight. The average diameter of the concrete after slump expansion is used as a fluidity indicator, namely the slump expansion.

[0004] The existing slump expansion measurement method mostly adopts manual measurement. The measurement personnel use a steel ruler to measure the average diameter of the concrete after collapse, and then obtain the slump expansion. This method has low measurement accuracy and efficiency.

[0005] Chinese patent CN112907512A discloses a method and device for testing the working performance of fresh self-compacting concrete. The measurement process is: first, complete the slump operation on the measuring board, further use digital cameras, smart phones and other image acquisition devices to take photos, then use image recognition technology to identify the contours of the measuring board and concrete, and finally calculate the slump expansion of the concrete based on the pixel size of the target length, the bit depth of the image and the actual size of the target length. However, the patent has the following defects:

[0006] During the measurement process, since the measuring board is located in the construction site with a complex background, it is difficult for image recognition technology to determine the location of the measuring board. At the same time, since the colors of the concrete and the measuring board may be similar to those of the surrounding site, the edge detection algorithm with a fixed threshold will find it difficult to effectively distinguish the contours, reducing the measurement accuracy of the concrete slump expansion. Summary of the invention

[0007] The purpose of the present invention is to provide a method for measuring the slump expansion of concrete in order to overcome the defects of the above-mentioned prior art. The present invention can accurately and efficiently measure the slump expansion of concrete.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides a method for measuring the slump spread of concrete, comprising the following steps:

[0010] S1: making a concrete slump spread model on a pre-set measuring device, and collecting a concrete slump spread image, wherein the image includes the measuring device and the concrete slump spread model;

[0011] S2: Performing contour recognition on the concrete slump spread image to generate and correct a contour image;

[0012] S3: determining the proportional relationship between the concrete slump expansion model contour and the measuring device contour according to the known actual size of the measuring device and the corrected contour image, and calculating the concrete slump expansion according to the proportional relationship and the actual size of the measuring device.

[0013] Preferably, the measuring device comprises a base plate, circular scale lines and a plurality of combination marks, the combination marks and the circular scale lines are both arranged on the base plate, the base plate is used for laying out the concrete slump-propagation model, and the circular scale lines are used for locating the slump cone.

[0014] Preferably, S2 specifically includes the following steps:

[0015] S201: obtaining a boundary threshold of the image by an adaptive threshold calculation algorithm, identifying the image contour by an edge detection algorithm based on the boundary threshold, generating a contour image, and determining the corresponding contours of the combined mark and the base plate according to the image contour;

[0016] S202: Establish a coordinate system on the contour image, determine the geometric center point of the corresponding contour of each combined mark and the coordinate information of the geometric center point, and correct the contour image based on the coordinate information of each geometric center point and the geometric relationship between each geometric center point.

[0017] Preferably, the adaptive threshold calculation algorithm includes the maximum inter-class variance method and the Bernsen algorithm.

[0018] Preferably, the edge detection algorithm includes Canny, Sobel and Laplacian algorithms.

[0019] Preferably, S3 specifically includes the following steps:

[0020] S301: Calculate the area of ​​each contour respectively, and then determine the contour corresponding to the concrete slump spread model;

[0021] S302: Determine the minimum circumscribed rectangle of the corresponding contour of the concrete slump spread model, and obtain the pixel value corresponding to the concrete slump spread model by calculating the pixel value corresponding to the average side length of the minimum circumscribed rectangle;

[0022] S303: Calculate the actual physical size of the concrete slump expansion model based on the actual size of the line connecting the geometric center points of adjacent combined marks in the known base plate and the proportional relationship between the line connecting the geometric center points of adjacent combined marks and the pixel values ​​corresponding to the concrete slump expansion model.

[0023] Preferably, the formula describing the actual physical dimensions of the concrete slump expansion model is specifically:

[0024]

[0025] Where D is the actual physical size of the concrete slump expansion model, d is the pixel value corresponding to the concrete slump expansion model, L is the actual physical size of the line connecting the center points of adjacent combination marks, and l is the pixel value of the line connecting the center points of adjacent combination marks.

[0026] Preferably, the plurality of combined marks are respectively arranged at corner points of the base plate.

[0027] Preferably, the circular scale line is located at the center of the base plate.

[0028] Preferably, before executing S2, the concrete slump spread image collected in S1 is preprocessed, and the preprocessing includes, for example, noise reduction and graying.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention provides a method for measuring the slump spread of concrete. By arranging combined marks at the corner points of the bottom plate, an edge detection algorithm can quickly determine the location of the corner points of the bottom plate according to the number of contour nesting layers, thereby improving the measurement speed and efficiency of the slump spread of concrete.

[0031] (2) The present invention provides a method for measuring the slump expansion of concrete. By adopting an adaptive threshold edge detection algorithm, the boundary threshold of the edge detection algorithm can be automatically adjusted according to the characteristics of the image itself, thereby solving the problem that the contour distinction effect is poor when the target and background colors are similar and the light is dark, which in turn affects the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic flow chart of a method for measuring the slump expansion of concrete provided in this embodiment.

[0033] Figure 2 for Figure 1 A schematic diagram of the structure of the measuring device in the illustrated embodiment.

[0034] Figure 3 for Figure 2 Top view of the illustrated embodiment.

[0035] Figure 4 for Figure 2 A schematic diagram of the structure of a combined mark in the illustrated embodiment.

[0036] Figure 5 for Figure 2 A schematic diagram of the number of nested layers of the outline of the combined logo of the illustrated embodiment.

[0037] Figure 6 for Figure 2 A schematic diagram of the structure of the combined mark outline and the combined mark geometric center point in the embodiment;

[0038] Figure 7 Schematic diagram of the corrected contour image.

[0039] The accompanying drawings are marked as follows: 1. combination mark, 2. base plate, 3. circular scale line, 4. outer wall, 5. notch, 6. internal column, 7. first outline of combination mark, 8. second outline of combination mark, 9. third outline of combination mark, 10. line connecting the geometric center points of adjacent combination marks. DETAILED DESCRIPTION

[0040] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0041] refer to Figure 1 As shown, this embodiment provides a method for measuring the slump spread of concrete, comprising the following steps:

[0042] S1: making a concrete slump expansion model on a pre-set measuring device, and collecting a concrete slump expansion image, wherein the concrete slump expansion image includes the measuring device and the concrete slump expansion model.

[0043] As an optional implementation, refer to Figure 2 and Figure 3 As shown, the measuring device includes a base plate 2, circular scale lines 3 and a plurality of combination marks 1. The combination marks 1 and the circular scale lines 3 are both arranged on the base plate 2. The base plate 2 is used to lay out the concrete slump expansion model, and the circular scale lines 3 are used to locate the slump cone.

[0044] As an optional implementation, a plurality of combination marks 1 are respectively arranged at each corner point of the bottom plate 2 .

[0045] As an optional implementation, the circular scale line 3 is located at the center of the bottom plate 2, and the diameter of the circular scale line 3 is slightly larger than the diameter of the lower opening of the collapse cone.

[0046] S101: placing a base plate 2 on a horizontal ground, and placing a standard cone slump cone centered within a circular scale line 3 on the base plate 2;

[0047] S102: A slump expansion model is made according to a standard method. When the expansion of the model stops increasing, the bottom plate 2 is photographed by an image acquisition device to acquire a concrete slump expansion image.

[0048] As an optional implementation, the image acquisition device includes a smart phone and a high-definition camera, and the vertical distance between the lens of the image acquisition device and the base plate 2 is greater than 1 meter.

[0049] It should be noted that the concrete slump expansion model is arranged on the bottom plate 2 and will not overflow the bottom plate 2 .

[0050] As an optional implementation, before executing S2, the concrete slump spread image collected in S1 is preprocessed, and the preprocessing includes, for example, noise reduction and graying.

[0051] S2: Perform contour recognition on the concrete slump spread image, generate and correct the contour image.

[0052] S201: Obtain the boundary threshold of the image through an adaptive threshold calculation algorithm, identify the image contour through an edge detection algorithm based on the boundary threshold, generate a contour image, and determine the corresponding contours of the combined mark 1 and the base plate 2 according to the image contour.

[0053] refer to Figure 4 As shown, the combined mark 1 provided in this embodiment includes an outer wall 4, a notch 5 and an inner column 6 from the outside to the inside. Since the combined mark 1 of this embodiment is provided at the corner point of the bottom plate 2, the number of nested layers of the combined mark 1 of this embodiment is 3 layers from the image contour. By finding the contour with the number of nested layers of 3 layers in the image contour, the corresponding contours of the combined mark 1 and the bottom plate 2 are determined. Figure 5 As shown, from outside to inside are the first outline 7 of the combined mark, the second outline 8 of the combined mark and the third outline 9 of the combined mark.

[0054] As an optional implementation, the adaptive threshold calculation algorithm includes but is not limited to the maximum inter-class variance method, Bernsen algorithm, etc., that is, clustering, averaging, etc. are used to obtain the boundary threshold of the adaptive image characteristics and edge detection algorithm.

[0055] As an optional implementation, the edge detection algorithm includes but is not limited to Canny, Sobel, and Laplacian algorithms.

[0056] S202: Establish a coordinate system on the contour image, determine the geometric center point of the corresponding contour of each combination mark 1 and the coordinate information of the geometric center point, and correct the contour image based on the coordinate information of each geometric center point and the geometric relationship between each geometric center point.

[0057] In this embodiment, a coordinate system is established with the lower left corner of the contour image as the origin, the right as the positive direction of the X-axis, and the upward as the positive direction of the Y-axis, to determine the horizontal and vertical coordinates of the geometric center point of each combination mark 1; the point with the smallest sum of the horizontal and vertical coordinate values ​​is the geometric center point of the combination mark 1 located at the lower left corner of the base plate 2, and the point with the largest sum of the horizontal and vertical coordinate values ​​is the geometric center point of the combination mark 1 located at the upper right corner of the base plate 2. For the remaining two geometric center points of the combination marks 1, the one with the larger vertical coordinate is the geometric center point of the combination mark 1 located at the upper left corner of the base plate 2, and the one with the smaller vertical coordinate is the geometric center point of the combination mark 1 located at the upper left corner of the base plate 2. For details, refer to reference Figure 6 The coordinate values ​​of the four geometric center points are necessary parameters of the perspective transformation model. The perspective transformation can be used to correct the slump spread image, transform the image in the natural shooting state into a vertical top view, and remove useless information in the image. Figure 7 shown.

[0058] S3: Measure the actual size of the measuring device and record it for subsequent use, determine the proportional relationship between the concrete slump expansion model contour and the measuring device contour according to the corrected contour image, and calculate the concrete slump expansion according to the proportional relationship and the actual size of the measuring device.

[0059] S301: Calculate the area of ​​each contour respectively by using the contourArea function of OpenCV, and then determine the contour corresponding to the concrete slump spread model.

[0060] refer to Figure 7 As shown in FIG. 1 , only the bottom plate 2, the concrete slump expansion model and the combination mark 1 remain in the corrected contour image. Since the concrete slump expansion model is approximately circular and its diameter is generally not less than 200 mm, and the area of ​​concrete is much larger than other objects, Figure 7 The contour with the largest area corresponds to the contour of the concrete slump expansion model.

[0061] S302: Determine the minimum circumscribed rectangle of the corresponding contour of the concrete slump spread model by using the minAreaRect function of OpenCV, and obtain the pixel value corresponding to the concrete slump spread model by calculating the pixel value corresponding to the average side length of the minimum circumscribed rectangle.

[0062] Among them, the minimum circumscribed rectangle is the maximum diameter of the concrete slump spread model; the width of the minimum circumscribed rectangle is the minimum diameter of the concrete slump spread model.

[0063] S303: Measure the actual size of the line 10 of geometric center points of adjacent combination marks in the base plate 2 and record it for subsequent use. Based on the proportional relationship between the line 10 of geometric center points of adjacent combination marks and the pixel values ​​corresponding to the concrete slump expansion model, calculate the actual physical size of the concrete slump expansion model.

[0064] The formula that describes the actual physical dimensions of the concrete slump model is:

[0065]

[0066] Where D is the actual physical size of the concrete slump expansion model, d is the pixel value corresponding to the concrete slump expansion model, L is the actual physical size of the line connecting the center points of adjacent combination marks, and l is the pixel value of the line connecting the center points of adjacent combination marks.

[0067] In summary, the present invention provides a method for measuring the slump spread of concrete. By arranging a combination mark at the corner point of the bottom plate, the edge detection algorithm can quickly determine the location of the bottom plate corner point according to the number of contour nesting layers, thereby improving the measurement speed and efficiency of the slump spread of concrete. By adopting an adaptive threshold edge detection algorithm, the boundary threshold of the edge detection algorithm can be automatically adjusted according to the characteristics of the image itself, solving the problem of poor contour distinction when the target and background colors are similar and the light is dark, which in turn affects the measurement results.

[0068] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for measuring the slump expansion of concrete, characterized in that: The steps include: S1: making a concrete slump spread model on a pre-set measuring device, and collecting a concrete slump spread image, wherein the image includes the measuring device and the concrete slump spread model; S2: performing contour recognition on the concrete slump spread image, generating and correcting a contour image; S3: determining the proportional relationship between the concrete slump expansion model contour and the measuring device contour according to the known actual size of the measuring device and the corrected contour image, and calculating the concrete slump expansion according to the proportional relationship and the actual size of the measuring device; The measuring device comprises a base plate (2), circular scale lines (3) and a plurality of combination marks (1), wherein the combination marks (1) and the circular scale lines (3) are both arranged on the base plate (2), the base plate (2) is used for laying out the concrete slump spread model, and the circular scale lines (3) are used for locating the slump cone; The plurality of combined marks (1) are respectively arranged at each corner point of the bottom plate (2); The combined mark (1) includes, from outside to inside, an outer wall (4), a notch (5) and an inner column (6), and the combined mark (1) has three nested layers. By searching for a contour with three nested layers in the image contour, the corresponding contours of the combined mark (1) and the base plate (2) are determined, which are, from outside to inside, a first contour of the combined mark (7), a second contour of the combined mark (8) and a third contour of the combined mark (9); S2 specifically includes the following steps: S201: Obtaining a boundary threshold of the image through an adaptive threshold calculation algorithm, identifying the image contour through an edge detection algorithm based on the boundary threshold, generating a contour image, and determining the corresponding contours of the combined mark (1) and the base plate (2) according to the image contour; S202: Establish a coordinate system on the contour image, determine the geometric center point of the corresponding contour of each combination mark (1) and the coordinate information of the geometric center point, and correct the contour image based on the coordinate information of each geometric center point and the geometric relationship between each geometric center point.

2. A method for measuring the slump expansion of concrete according to claim 1, characterized in that: The adaptive threshold calculation algorithm includes the maximum inter-class variance method and the Bernsen algorithm.

3. A method for measuring the slump expansion of concrete according to claim 1, characterized in that: The edge detection algorithms include Canny, Sobel and Laplacian algorithms.

4. A method for measuring the slump expansion of concrete according to claim 1, characterized in that: S3 specifically includes the following steps: S301: Calculate the area of ​​each contour respectively, and then determine the contour corresponding to the concrete slump spread model; S302: Determine the minimum circumscribed rectangle of the corresponding contour of the concrete slump spread model, and obtain the pixel value corresponding to the concrete slump spread model by calculating the pixel value corresponding to the average side length of the minimum circumscribed rectangle; S303: According to the actual size of the line (10) connecting the geometric center points of adjacent combination marks in the known base plate (2), based on the proportional relationship between the line (10) connecting the geometric center points of adjacent combination marks and the pixel values ​​corresponding to the concrete slump expansion model, the actual physical size of the concrete slump expansion model is calculated.

5. A method for measuring the slump expansion of concrete according to claim 4, characterized in that: The formula that describes the actual physical dimensions of the concrete slump model is: Where D is the actual physical size of the concrete slump expansion model, d is the pixel value corresponding to the concrete slump expansion model, L is the actual physical size of the line connecting the center points of adjacent combination marks, and l is the pixel value of the line connecting the center points of adjacent combination marks.

6. A method for measuring the slump expansion of concrete according to claim 1, characterized in that: The circular scale line (3) is located at the center of the bottom plate (2).

7. A method for measuring the slump expansion of concrete according to claim 1, characterized in that: Before executing S2, the concrete slump spread image collected by S1 is preprocessed, and the preprocessing includes noise reduction and graying.

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