A three-dimensional evaluation method for homogeneity of a concrete member based on aggregate particle characteristics

Abstract

The application provides a kind of concrete component homogeneity three-dimensional evaluation method based on aggregate particle characteristics, belongs to concrete performance detection technical field.The steps are: selecting the thickness variation coefficient of mortar coating and the variation coefficient of aggregate particle number as the core evaluation index;Determine the concrete homogeneity classification evaluation standard, the standard includes;Using image processing technology to process the concrete component, obtain the three-dimensional space coordinates and morphology data of the aggregate and mortar phase inside the component through multi-section data fusion, generate a three-dimensional entity model;Statistical and calculate the thickness variation coefficient of mortar coating and the variation coefficient of aggregate particle number;Put the core index into the classification evaluation standard, obtain the three-dimensional homogeneity evaluation grade of the concrete component, and compare the two-dimensional section evaluation result to verify the applicability and rationality of the method.The application can realize the complete characterization of the three-dimensional space structure of the concrete component, improve the scientificity, accuracy and practicability of the homogeneity evaluation.

Description

Technical Field

[0001] This invention relates to the field of concrete performance testing technology, specifically to a three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics. Background Technology

[0002] Concrete, as the most widely used building material in the world today, directly determines the mechanical properties, durability, and long-term service safety of structures through the homogeneity of its components, making it a core indicator for engineering quality control. Currently, the evaluation of concrete homogeneity in engineering practice mainly relies on two-dimensional cross-sectional analysis methods. This method involves observing cross-sections cut at specific locations within a component and analyzing the aggregate distribution (such as aggregate area ratio) to indirectly infer the overall homogeneity of the component. While this method is relatively simple to operate, it only reflects local information from a single cross-section and cannot fully characterize the complex distribution of multiphase materials such as aggregates, mortar, and pores within the concrete in three-dimensional space. Therefore, it is difficult to accurately and comprehensively assess the overall homogeneity level of the component.

[0003] Existing two-dimensional cross-section evaluation methods have significant limitations. On the one hand, they cannot capture three-dimensional information such as internal defects, segregation, or uneven aggregate distribution in the three-dimensional space of the component, leading to randomness and bias in the evaluation results, which may mislead the judgment of engineering quality. On the other hand, traditional methods often use the aggregate area ratio as the core or even the only evaluation indicator, ignoring key spatial distribution characteristics such as the quantity distribution, spacing, and uniformity of the mortar coating layer of aggregate particles, resulting in insufficient accuracy and reliability of the evaluation results.

[0004] As infrastructure becomes larger and more complex, and the requirements for project lifespan and durability continue to increase, the need for precise and three-dimensional evaluation of the internal quality of concrete components is becoming increasingly urgent. Therefore, the industry urgently needs a technology that can overcome the limitations of two-dimensional analysis, enabling a precise and scientific evaluation of the overall homogeneity of concrete components from a three-dimensional spatial scale, comprehensively utilizing the multi-dimensional characteristics of aggregate distribution. This would overcome the technical difficulties of incomplete and inaccurate evaluation in existing technologies, providing more reliable technical support for engineering quality control. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing methods for evaluating the homogeneity of concrete, which rely on two-dimensional cross-sections and have only a single index, and to provide a three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics. This method can achieve a complete characterization of the three-dimensional spatial structure of concrete components, comprehensively consider the multi-dimensional characteristics of aggregate particle distribution, and improve the scientificity, accuracy, and practicality of homogeneity evaluation.

[0006] A three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics includes the following steps: S1. Construct a core index system for evaluating the homogeneity of concrete components, and select the coefficient of variation of mortar coating thickness and the coefficient of variation of aggregate particle number as core evaluation indicators. S2. Determine the evaluation criteria for the homogeneity grading of concrete, wherein the criteria include: Superior grade: The coefficient of variation of mortar coating thickness is less than 1 and the coefficient of variation of aggregate particle number is less than 0.3; Good grade: The coefficient of variation of mortar coating thickness is less than 1 and the coefficient of variation of aggregate particle number is greater than 0.3; Intermediate: The coefficient of variation of the mortar coating thickness is greater than or equal to 1 and the coefficient of variation of the aggregate particle number is less than 0.3; Poor grade: The coefficient of variation of mortar coating thickness is greater than or equal to 1 and the coefficient of variation of aggregate particle number is greater than or equal to 0.3; S3. Obtain three-dimensional spatial data of concrete components: Image processing technology is used to process concrete components, and the three-dimensional spatial coordinates and morphological data of aggregate and mortar phase inside the component are obtained through multi-section data fusion to generate a three-dimensional solid model. S4. Calculate the core evaluation indicators: Based on the three-dimensional solid model, traverse the entire volume range of the component, and statistically calculate the coefficient of variation of the mortar coating thickness and the coefficient of variation of the number of aggregate particles. S5. Homogeneity Evaluation and Verification: Substitute the core indicators calculated in step S4 into the grading evaluation criteria set in step S2 to obtain the three-dimensional homogeneity evaluation level of the concrete component, and compare the two-dimensional section evaluation results to verify the applicability and rationality of the method.

[0007] Preferably, in step S3, the image processing technology includes cutting, photographing, and binarizing the concrete component; wherein the selected detection cross-sectional size is not less than 4 times the maximum stone particle size in the component, and the maximum coarse aggregate particle size does not exceed 1 / 4 of the minimum cross-sectional size of the component.

[0008] Preferably, in step S3, the resolution of the photographed image is not less than 0.01mm, and the cutting and photographing process must ensure the continuity and integrity of each cross section.

[0009] Preferably, in step S4, the method for calculating the coefficient of variation of the mortar coating thickness includes: in the three-dimensional solid model, for each aggregate particle, at least 10 measurement points are uniformly selected along the surface normal direction, the distance from each measurement point to the aggregate surface is calculated as the local mortar coating thickness, the average value of the thickness of all measurement points is taken as the mortar coating thickness of the aggregate particle, and then the mortar coating thickness of all aggregate particles in the whole component is statistically analyzed, and the ratio of its standard deviation to the average value is calculated to obtain the coefficient of variation of the mortar coating thickness.

[0010] Preferably, in step S4, the method for calculating the coefficient of variation of aggregate particle quantity includes: uniformly dividing the three-dimensional solid model of the concrete component into several equal volume units, counting the number of aggregate particles in each unit, calculating the ratio of the standard deviation to the average value of the number of aggregate particles in all units, and obtaining the coefficient of variation of aggregate particle quantity.

[0011] Preferably, the method is applicable to concrete pier components in bridge engineering; during evaluation, three test points are selected along each section of the pier, and each test point has a test cross section of 150mm×150mm.

[0012] Preferably, the method is applicable to concrete segmental beam components in bridge engineering; during evaluation, the front, rear, and lower middle positions of the segmental beam are selected as test points, and each test point has a test cross section of 150mm×150mm.

[0013] In a further preferred embodiment, the selected test section is subjected to surface grinding to remove the surface mortar layer, so that the aggregate particles are clearly exposed.

[0014] In a further preferred embodiment, in step S3, the components are cut in layers and the cross-sectional data are fused to generate a three-dimensional solid model, wherein the thickness of each layer is controlled at 5mm.

[0015] A computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, it implements the steps of the three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics as described in any one of claims 1 to 9.

[0016] Compared with the prior art, the present invention achieves the following technical effects: Breaking through the limitations of two-dimensional cross-sectional analysis: This invention conducts evaluation based on three-dimensional spatial data of the entire volume of concrete components, which can completely and realistically characterize the spatial distribution of the multiphase structure inside concrete, avoiding the misleading effect of local information from two-dimensional cross-sections on the overall evaluation results, and improving the comprehensiveness and accuracy of the evaluation.

[0017] Constructing a multi-dimensional evaluation system: This invention comprehensively considers two core indicators: the coefficient of variation of mortar coating thickness and the coefficient of variation of aggregate particle number. It overcomes the one-sidedness of traditional methods that rely solely on the single indicator of aggregate area ratio, and can more comprehensively reflect the essential characteristics of concrete homogeneity.

[0018] The evaluation criteria are scientific and reliable: through clear quantitative index grading, the homogeneity of concrete is accurately graded and evaluated. Furthermore, the applicability and rationality of the method are further guaranteed by the comparison and verification of three-dimensional and two-dimensional evaluation results, providing more reliable technical support for the quality control of concrete engineering. Attached Figure Description

[0019] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 This is a schematic diagram showing the selection of the homogeneity test location for the pier column in Example 3.

[0021] Figure 2 This is a schematic diagram showing the selection of the homogeneity test location for the segmental beam in Example 3. Detailed Implementation

[0022] The following are specific embodiments of the present invention, described in conjunction with the accompanying drawings, to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0024] Example 1 This embodiment uses a C30 concrete cube specimen (150mm side length) as the evaluation object and employs the method of this invention to evaluate homogeneity. The specific steps are as follows: Specimen preparation: Cubic specimens were prepared according to the C30 concrete mix proportion (cement:sand:stone:water = 1:1.83:3.48:0.45) and cured under standard conditions for 28 days before use.

[0025] 3D data acquisition: Data is acquired using image processing techniques such as concrete specimen cutting, photography, and binarization. First, the specimen is cut along different directions to obtain multiple cross-sections. Each cross-section is photographed, and then the photos are binarized to extract the outline information of the aggregate and mortar phase. A 3D solid model of the aggregate and mortar phase inside the specimen is generated by fusing multi-section data.

[0026] Core indicator calculation: Calculation of the coefficient of variation of mortar coating thickness: In the three-dimensional solid model, 100 aggregate particles are randomly selected, and 12 measurement points are selected along the surface normal direction of each aggregate particle. The thickness of the mortar coating at each measurement point is calculated. The average thickness of the mortar coating of all aggregate particles is 2.5 mm, and the standard deviation is 2.0 mm. Therefore, the coefficient of variation of mortar coating thickness = 2.0 / 2.5 = 0.8.

[0027] Calculation of the coefficient of variation of aggregate particle number: The three-dimensional model of the specimen is evenly divided into three equal sections. The average number and standard deviation of the number of particles in each section are calculated to obtain the coefficient of variation of the particle number. The number of aggregate particles in each unit is counted, and the average number is 8, with a standard deviation of 2.0. Therefore, the coefficient of variation of aggregate particle number = 2.0 / 8 = 0.25.

[0028] Homogeneity evaluation: According to the grading standard, the coefficient of variation of mortar coating thickness is 0.8 < 1, and the coefficient of variation of aggregate particle number is 0.25 < 0.3. Therefore, the homogeneity evaluation level of this C30 concrete specimen is excellent.

[0029] Verification and comparison: The existing two-dimensional cross-section method was used to evaluate three different cross-sections of the specimen. Two cross-sections were rated as excellent and one as good, indicating a discrepancy in the evaluation results. However, the three-dimensional evaluation method of this invention is based on full-volume data, and the evaluation results are stable and consistent, verifying the superiority of this method.

[0030] Example 2 This embodiment uses a real concrete beam member (dimensions 500mm×200mm×2000mm) as the evaluation object, and the specific steps are as follows: 3D data acquisition: Image processing techniques such as concrete specimen cutting, photography, and binarization are used to acquire data for the beam components. The beam components are cut into segments, and each segment is cut at a set distance along the length direction to obtain multiple cross sections. After photographing each cross section, binarization processing is performed to extract the outline information of aggregate and mortar phases. The entire beam component is obtained by fusing and stitching the multi-section data.

[0031] Core indicator calculation: Traversing the entire volume of the beam component, the average thickness of the mortar coating layer was found to be 3.2mm, with a standard deviation of 3.5mm and a coefficient of variation of 3.5 / 3.2≈1.09; Dividing the beam component into 200 equal volume units, the average number of aggregate particles was 12, with a standard deviation of 4.8 and a coefficient of variation of 4.8 / 12=0.4.

[0032] Homogeneity evaluation: The coefficient of variation of mortar coating thickness is 1.09≥1, and the coefficient of variation of aggregate particle quantity is 0.4≥0.3. Therefore, the homogeneity evaluation level of this concrete beam component is poor.

[0033] Verification and comparison: Two-dimensional cross-sectional evaluation of the crack-prone parts of the beam components also yielded poor results, consistent with the three-dimensional evaluation results of this invention; at the same time, mechanical property tests were conducted on the beam components, and their compressive strength and flexural strength were both lower than the design requirements, further verifying the rationality of the evaluation method of this invention.

[0034] Example 3 (Specific Example for Bridge Concrete Components) This embodiment focuses on the homogeneity evaluation of core concrete components of bridges (piers, segmental beams) and, in accordance with actual engineering testing requirements, employs the method of this invention. The specific steps are as follows: 1. Evaluation of the homogeneity of pier components Test site selection: In accordance with the requirements of the "Code for Construction of Concrete Structures" GB50666, three test points are selected along each section of the pier. Each test point is selected with a test section of 150mm×150mm (the cross-sectional size is not less than 4 times the maximum aggregate size, and the maximum coarse aggregate size does not exceed 1 / 4 of the minimum cross-sectional size of the pier). The selected cross-section is surface treated by grinding to remove the mortar layer on the concrete surface, so that the aggregate (stone) is clearly exposed.

[0035] 3D data acquisition: Data is acquired using image processing techniques such as concrete specimen cutting, photography, and binarization. The test section of the pier is cut in layers at different depths, with each layer controlled to a thickness of 5mm. Each cut section is photographed (with a resolution of no less than 0.01mm). The photographs are then binarized to extract the contour information of the aggregate and mortar phases. A 3D solid model of the test area of ​​the pier is generated by fusing multi-section data.

[0036] Core indicator calculation: Traversing the entire volume range of the 3D solid model, the average thickness of the mortar coating layer was found to be 2.8mm, with a standard deviation of 2.2mm, and a coefficient of variation of 2.2 / 2.8≈0.79. The 3D model was uniformly divided into 81 equal volume units (each unit has a volume of 10mm×10mm×10mm), and the number of aggregate particles in each unit was counted. The average number was 9, with a standard deviation of 2.1. Therefore, the coefficient of variation of the number of aggregate particles was 2.1 / 9≈0.23.

[0037] Homogeneity evaluation: According to the grading standard, the coefficient of variation of mortar coating thickness is 0.79 < 1, and the coefficient of variation of aggregate particle number is 0.23 < 0.3. Therefore, the homogeneity evaluation level of the concrete in the test area of ​​the pier column is excellent.

[0038] 2. Evaluation of homogeneity of segmental beam members: Test site selection: Select a typical segment of the precast segmental beam and set one test point at each of the three key locations at the front, back, and bottom middle of the segmental beam. Each test point also selects a test section of 150mm×150mm (to meet the matching requirements of cross-sectional dimensions and aggregate particle size in the "Code for Construction of Concrete Structures" GB50666). The surface of each section is ground to remove the surface mortar layer and expose the aggregate.

[0039] 3D data acquisition: Using the same image processing techniques as those used for pier columns, such as concrete specimen cutting, photography, and binarization, the test points of the segmental beam were cut in layers (5mm thickness), photographed, and binarized. After extracting the aggregate and mortar phase contour information, the 3D solid model of each test point was generated by fusing multi-section data. The model was then stitched together to obtain the overall 3D homogeneity analysis model of the segment of the segmental beam.

[0040] Calculation of core indicators: The coefficients of variation of mortar coating thickness in the front, back and lower middle test areas of the segmental beam were 0.85, 0.92 and 0.88, respectively, all <1; the coefficients of variation of aggregate particle number were 0.35, 0.32 and 0.34, respectively, all >0.3.

[0041] Homogeneity evaluation: According to the grading standard, the homogeneity evaluation level of the concrete of this precast segmental beam is good.

[0042] Verification and comparison: The two-dimensional cross-sections of each test point were evaluated separately, and the results were consistent with the three-dimensional evaluation results. At the same time, combined with the construction records of the segmental beam, the slight differences in the vibration parameters during the pouring process were consistent with the homogeneity evaluation results, which verified the applicability of the method of the present invention in the evaluation of actual bridge engineering components.

[0043] Those skilled in the art to which this application pertains may modify or supplement the specific embodiments described or use similar methods to replace them, but without departing from the inventive concept of this application or exceeding the scope defined by the appended claims.

Claims

1. A three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics, characterized in that, Includes the following steps: S1. Construct a core index system for evaluating the homogeneity of concrete components, and select the coefficient of variation of mortar coating thickness and the coefficient of variation of aggregate particle number as core evaluation indicators. S2. Determine the evaluation criteria for the homogeneity grading of concrete, wherein the criteria include: Superior grade: The coefficient of variation of mortar coating thickness is less than 1 and the coefficient of variation of aggregate particle number is less than 0.3; Good grade: The coefficient of variation of mortar coating thickness is less than 1 and the coefficient of variation of aggregate particle number is greater than 0.3; Intermediate: The coefficient of variation of the mortar coating thickness is greater than or equal to 1 and the coefficient of variation of the aggregate particle number is less than 0.3; Poor grade: The coefficient of variation of mortar coating thickness is greater than or equal to 1 and the coefficient of variation of aggregate particle number is greater than or equal to 0.3; S3. Obtain three-dimensional spatial data of concrete components: Image processing technology is used to process concrete components, and the three-dimensional spatial coordinates and morphological data of aggregate and mortar phase inside the component are obtained through multi-section data fusion to generate a three-dimensional solid model. S4. Calculate the core evaluation indicators: Based on the three-dimensional solid model, traverse the entire volume range of the component, and statistically calculate the coefficient of variation of the mortar coating thickness and the coefficient of variation of the number of aggregate particles. S5. Homogeneity Evaluation and Verification: Substitute the core indicators calculated in step S4 into the grading evaluation criteria set in step S2 to obtain the three-dimensional homogeneity evaluation level of the concrete component, and compare the two-dimensional section evaluation results to verify the applicability and rationality of the method.

2. The method according to claim 1, characterized in that, In step S3, the image processing technology includes cutting, photographing and binarizing the concrete component; wherein, the selected detection cross-sectional size is not less than 4 times the maximum stone particle size in the component, and the maximum coarse aggregate particle size does not exceed 1 / 4 of the minimum cross-sectional size of the component.

3. The method according to claim 2, characterized in that, In step S3, the resolution of the photographed image should be no less than 0.01mm, and the cutting and photographing process should ensure the continuity and integrity of each cross section.

4. The method according to claim 1, characterized in that, In step S4, the calculation method for the coefficient of variation of the mortar coating thickness includes: in the three-dimensional solid model, for each aggregate particle, at least 3 measurement points are uniformly selected along the surface normal direction, the distance from each measurement point to the aggregate surface is calculated as the local mortar coating thickness, the average value of the thickness of all measurement points is taken as the mortar coating thickness of the aggregate particle, and then the mortar coating thickness of all aggregate particles in the whole component is statistically analyzed, and the ratio of its standard deviation to the average value is calculated to obtain the coefficient of variation of the mortar coating thickness.

5. The method according to claim 1, characterized in that, In step S4, the method for calculating the coefficient of variation of aggregate particle quantity includes: uniformly dividing the three-dimensional solid model of the concrete component into several equal volume units, counting the number of aggregate particles in each unit, calculating the ratio of the standard deviation to the average value of the number of aggregate particles in all units, and obtaining the coefficient of variation of aggregate particle quantity.

6. The method according to claim 1, characterized in that, The method is applicable to concrete pier components in bridge engineering; during evaluation, three test points are selected along each section of the pier, and each test point has a test cross section of 150mm×150mm.

7. The method according to claim 1, characterized in that, The method is applicable to concrete segmental beam components in bridge engineering. During evaluation, the front, rear, and lower middle positions of the segmental beam are selected as test points, and each test point has a test section of 150mm×150mm.

8. The method according to claim 6 or 7, characterized in that, The selected test section is ground to remove the surface mortar layer and expose the aggregate particles clearly.

9. The method according to claim 1, characterized in that, In step S3, the components are cut in layers and the cross-sectional data are fused to generate a three-dimensional solid model, wherein the thickness of each layer is controlled at 5mm.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the three-dimensional evaluation method for the homogeneity of concrete components based on aggregate particle characteristics as described in any one of claims 1 to 9.

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