Method for defining multistage dispersion system of asphalt mixture

Abstract

The invention discloses an asphalt mixture multistage dispersion system defining method which comprises the following steps: acquiring a slice scanning image of an asphalt mixture test piece, and performing three-dimensional reconstruction on the slice image of the asphalt mixture test piece; dividing an interface pure asphalt area, a mucilage area and a mortar area through the three-dimensional reconstruction model of the asphalt concrete test piece; considering the adsorption influence of the aggregate surface appearance on the asphalt, and correcting the division range of the three-stage dispersion system of the interface area in combination with the calculation of the equivalent asphalt content. According to the method, a three-dimensional reconstruction model is constructed by using test piece slices scanned by nano industrial CT, a new asphalt mixture cross-scale multi-stage three-stage dispersion system definition is provided, and the problem that the definition standard of the asphalt mixture cross-scale multi-stage dispersion system is lacked is solved.

Description

Technical Field

[0001] The invention belongs to the field of asphalt mixture evaluation methods, and in particular relates to a method for defining a multi-level dispersion system of an asphalt mixture. Background Art

[0002] Asphalt mixture, as an asphalt pavement material, is an engineering material of a multi-level dispersed system. The macroscopic phenomenological empirical judgment method cannot accurately predict the deterioration evolution law of asphalt concrete, resulting in the service life of asphalt pavements in my country often failing to reach the designed life. The structural stability of asphalt mixtures mainly comes from the intercalation of the aggregate skeleton and the adhesion interaction between the asphalt and aggregate interfaces. Among them, the fracture damage of the asphalt mixture interface phase as the weakest area is often the main cause of pavement diseases. Therefore, studying the distribution of the asphalt mixture dispersion system and revealing the strength formation mechanism and deterioration evolution law of asphalt mixtures are of great significance to the improvement and prediction of pavement performance.

[0003] The construction of the traditional asphalt mixture dispersion system is based on the principle of conceptual explanation and mechanism interpretation. The boundary definition between each dispersion system is difficult to reflect. At the same time, due to the three-level dispersion system spatial network structure adopted by the mortar theory, it is impossible to guide the division of multi-scale material components of asphalt mixtures, resulting in the mechanism of interaction between the various components is not yet clear. Therefore, there is currently a lack of standards for defining cross-scale multi-level dispersion systems of asphalt mixtures, making it difficult to reveal the strength formation mechanism and deterioration evolution law of asphalt mixtures from a multi-scale perspective. Summary of the invention

[0004] The main purpose of the present invention is to solve the problem of lack of definition standards for cross-scale multi-level dispersion systems of asphalt mixtures, and to propose a method for defining multi-level dispersion systems of asphalt mixtures.

[0005] To this end, the present invention provides a method for defining a multi-stage dispersion system of an asphalt mixture, and the specific steps are as follows:

[0006] S1: Collecting slice scanning images of asphalt mixture specimens, reconstructing the slice images of asphalt mixture specimens in three dimensions, and screening out aggregates of different particle sizes;

[0007] S2: Using the three-dimensional reconstruction model obtained in S1, the interface area is divided into a three-level dispersion system, the interface area is divided into an interface transition area and an asphalt mortar area, and the interface transition area is divided into a pure asphalt area and a mortar area;

[0008] The measurement function of Avizo software is used to measure the distribution thickness of the pure asphalt area. The distribution interval of the data range of the measured pure asphalt area distribution thickness is summarized and analyzed to obtain the overall pure asphalt area range of the specimen. The distribution range of the asphalt mortar is determined by combining the distribution of the aggregates of 0.075 mm and below screened in step S1. The asphalt mortar distribution range of the three-dimensional reconstructed specimen is then divided into four parts using Avizo software for measurement. The data is analyzed to obtain the distribution range of the mortar thickness in the interface area. The distribution range of the specimen mortar is obtained in the same way as the asphalt mortar.

[0009] S3: organic washing, filtration and drying of aggregates, weighing the total asphalt mass, considering the effect of aggregate surface morphology on asphalt adsorption, and then calculating the equivalent asphalt content, and correcting the three-level dispersion system division range of the interface area;

[0010] First, the aggregate is washed multiple times with an organic solvent, the washed asphalt solution is filtered through a filter device, and the filtrate is vacuum filtered using a filter pump. After the filtration is completed, the aggregate on the filter paper is dried and weighed using a high-precision electronic scale to obtain the total mass of the asphalt.

[0011] Next, considering the influence of asphalt adsorbed on the aggregate surface on asphalt thickness, the mass of asphalt absorbed by the aggregate surface morphology was calculated by referring to the calculation formula (2) for the proportion of asphalt binder absorbed by aggregate in asphalt mixture;

[0012] M 吸附 =M 洗涤后 ×P ba (2)

[0013] Among them, M 吸附 Indicates the mass of asphalt absorbed by the aggregate surface morphology, M 洗涤后 It represents the mass of coarse aggregate after repeated washing, except for surface fine aggregate and asphalt, P ba Indicates the proportion of asphalt absorbed by aggregate.

[0014] Next, the asphalt content attached to the aggregate in the asphalt mortar is calculated by equivalent asphalt content calculation;

[0015] Next, the asphalt adsorbed on the aggregate surface and the asphalt wrapped in the aggregate in the asphalt mortar are comprehensively considered, the masses of the two are taken out from the total asphalt mass, and the asphalt content in the interface transition zone is calculated.

[0016] Next, the volume of asphalt is calculated by the asphalt content and density on the aggregate surface, and then the volume of mineral powder is calculated according to the mass and density of mineral powder, and finally the mixed density of asphalt on the coarse aggregate surface is calculated according to the mass of asphalt and mineral powder;

[0017] Finally, the volume is calculated based on the asphalt mass and mixed density of the interface transition zone, and then the thickness range of the interface transition zone is calculated based on the surface area. At the same time, the thickness of the asphalt mortar area is corrected based on the pure asphalt area range calculated in step S2.

[0018] The steps for calculating the equivalent asphalt content are as follows: the asphalt in the asphalt mixture is divided into effective asphalt and asphalt adsorbed by mineral aggregates, and the effective asphalt content in the asphalt mixture and the 0.075 mm passing rate P in the mineral aggregate grading are calculated. 0.075 The ratio of powder to glue ratio FB is based on the principle that the asphalt content adsorbed by the asphalt mortar mineral material is consistent with the powder to glue ratio. 0.075 It is replaced by the 0.075mm pass rate in the asphalt mortar to obtain the asphalt content attached to the aggregate in the asphalt mortar.

[0019] Specifically, step S1 includes the following steps:

[0020] Firstly, a rutting plate specimen is provided, and core sampling is performed at the interface area of ​​the specimen;

[0021] Use nano-industrial CT to scan the core specimen and obtain CT scan images of the specimen slices;

[0022] Use image processing software to export the raw format image files reconstructed from CT scans into single slice image files;

[0023] The slice images are processed using digital image processing technology to accurately study the distribution characteristics of the microstructure of the asphalt mixture interface area;

[0024] The segmented image processed by digital image processing technology is subjected to threshold segmentation and reconstruction of the three-dimensional visualization of the coring specimen;

[0025] Finally, the aggregates of the reconstructed specimens are separated to obtain the volume and other characteristic parameters of each aggregate. The volume information of the aggregate is extracted, and the corresponding equivalent diameter is calculated according to the principle of equal volume. According to the particle size information of the aggregate, aggregates of different particle sizes are screened to complete the three-dimensional reconstruction of aggregates of different particle sizes.

[0026] Specifically, the digital image processing technology is an image segmentation technology based on a deep learning network model.

[0027] Specifically, the three-dimensional visualization of the reconstructed specimens was achieved using Avizo software.

[0028] Specifically, Where V represents the volume of aggregate and D represents the particle size of aggregate.

[0029] Specifically, the screening principle of aggregates of different particle sizes is: particle sizes of 0-0.075mm are divided into one group, which is the distribution of asphalt mortar filler; particle sizes of 0.075mm-2.36mm are divided into one group, which is the distribution of asphalt mortar fine aggregate; finally, particle sizes above 2.36 are used as coarse aggregate.

[0030] Specifically, the analysis method is to statistically analyze a large amount of thickness range data. For the pure asphalt area thickness with small data discreteness, the proportion of its pure asphalt area distribution thickness is calculated, and the thickness with a proportion of more than 5% is taken as the pure asphalt area thickness range. For the mortar area thickness and the mortar area thickness with large data discreteness, the minimum and maximum values ​​of the entire data set are taken as the area thickness range;

[0031] Specifically, the three-dimensional reconstructed specimen was divided into four parts for measurement: from top to bottom, 25%, 50%, 75% and 100% of the volume of the reconstructed specimen were measured respectively;

[0032] Specifically, the multi-level three-level dispersion system of the new asphalt mixture is as follows: the pure asphalt area (micrometer level) is dispersed in the pure mortar area to form an interface transition zone (hundred-micrometer level), the coarse aggregate as the dispersed phase is dispersed in the interface transition zone to form a coarse aggregate skeleton (millimeter level), and the coarse aggregate skeleton is dispersed in the asphalt mortar area to form an asphalt mixture with an interwoven network structure.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention innovatively proposes a method for defining a multi-level dispersion system of asphalt mixtures. It uses a three-dimensional reconstruction model constructed by using specimen slices scanned by industrial CT to propose a new definition of a cross-scale multi-level three-level dispersion system of asphalt mixtures, solving the problem of the lack of a definition standard for a cross-scale multi-level dispersion system of asphalt mixtures. The present invention provides a theoretical premise for accurately predicting the deterioration evolution law of asphalt concrete, which is of great significance for studying the durability of asphalt mixtures.

[0035] 2. The present invention takes into account the effect of aggregate surface morphology on the adsorption of asphalt, calculates the volume by calculating the equivalent asphalt content and the mixed density, and then calculates the thickness range of the interface transition zone in combination with the surface area, and corrects the division range of the three-level dispersion system in the interface area, making the division range of the three-level dispersion system more accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 Displayed as a multi-scale grouping diagram of asphalt mixture;

[0038] Figure 2 Shown is a map of the determination of the distribution range of the pure asphalt area;

[0039] Figure 3 Displayed as a histogram of the thickness percentage of pure asphalt area distribution;

[0040] Figure 4 The display is a schematic diagram of asphalt mortar distribution;

[0041] Figure 5 The display is a schematic diagram of the equal division of the specimen;

[0042] Figure 6 Displayed as a distribution diagram of the thickness range of the asphalt mortar area;

[0043] Figure 7 The display is a three-dimensional reconstruction of the mortar distribution of the specimen;

[0044] Figure 8 Displayed as a box plot of the asphalt mortar distribution range;

[0045] Fig. 9 Shown is the trend diagram of indentation modulus change at different points. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] This method uses nanoscale industrial CT to obtain digital images of core specimens, uses deep learning image segmentation algorithms to perform image segmentation, and uses Avizo software to perform three-dimensional reconstruction of the digital images processed by deep learning segmentation to study the distribution characteristics and range of each level of dispersion system in the interface area of ​​asphalt mixtures. The range of the divided three-level dispersion system is verified by nanoindentation and scanning electron microscopy, as well as organic washing and particle size analysis of aggregates after real mixing and asphalt coating.

[0048] The present invention proposes a method for defining a multi-stage dispersion system of an asphalt mixture, which specifically comprises the following steps:

[0049] Step S1: collecting a slice scanning image of the asphalt mixture specimen, performing three-dimensional reconstruction on the slice image of the asphalt mixture specimen, and screening out aggregates of different particle sizes;

[0050] First, coring is performed at the interface area of ​​the asphalt concrete specimen. As an example, the diameter of the coring specimen is 5 mm, the height is 10 mm, and the number of coring specimens is 3.

[0051] Next, the core specimen is scanned using a nano-industrial CT to obtain CT scan images of the specimen slices.

[0052] Next, the image processing software is used to export the raw image file reconstructed from the CT scan into a single slice image file. As an example, the raw image file obtained from the CT scan is exported using Image J software into a png format image that can be used for subsequent segmentation processing. The image size is 2800×2800, and the number of exported images is 2300.

[0053] Next, the slice images were processed using digital image processing technology to accurately study the distribution characteristics of the microstructure of the asphalt mixture interface area. As an example, the image processing technology of U-Net deep learning network model image segmentation was used to perform semantic segmentation on the asphalt mixture image obtained by high-precision nano CT scanning to obtain the microscopic distribution of the interface area.

[0054] Finally, the segmented images after batch processing based on the U-Net semantic segmentation model are imported into the Avizo software, and the Interactive Thresholding module is used for threshold segmentation. Then, the Volume Rendering module is used to realize the three-dimensional visualization of the coring specimen reconstructed based on the slice image. Then, the Separate Objects module is used to separate the aggregates of the reconstructed specimen. The LableAnalysis module is used to obtain the volume and other characteristic parameters of each aggregate. Then, the volume information of the aggregates in the LableAnalysis module is extracted. The corresponding equivalent diameter of the three-dimensionally reconstructed aggregate is calculated according to the volume equality principle as shown in formula (1):

[0055]

[0056] Where V represents the volume of aggregate and D represents the particle size of aggregate.

[0057] According to the aggregate particle size information, the Filter by measure module is used to screen aggregates of different particle sizes and complete the three-dimensional reconstruction of aggregates of different particle sizes.

[0058] Specifically, the screening principle of aggregates of different particle sizes is: particle sizes of 0-0.075mm are divided into one group, which is the distribution of asphalt mortar filler; particle sizes of 0.075mm-2.36mm are divided into one group, which is the distribution of asphalt mortar fine aggregate; finally, particle sizes above 2.36 are used as coarse aggregate.

[0059] Step S2: using the three-dimensional reconstruction model obtained in S1 to divide the interface into pure asphalt area, glue area, and mortar area;

[0060] Firstly, a new definition of asphalt mixture cross-scale multi-level three-level dispersion system is proposed: Figure 1 :The pure asphalt area (micrometer level) is dispersed in the pure mortar area to form an interface transition zone (hundred micrometer level), the coarse aggregate as a dispersed phase is dispersed in the interface transition zone to form a coarse aggregate skeleton (millimeter level), and the coarse aggregate skeleton is dispersed in the asphalt mortar area to form an asphalt mixture with an interwoven network structure.

[0061] Next, the measurement function of Avizo software was used to measure the thickness of the pure asphalt area distribution in the interface area. The measurement method is shown in Figure 2. After the measurement, the distribution interval of the pure asphalt area distribution thickness data range obtained by the measurement was summarized and analyzed to obtain the proportion of different thickness distributions of the pure asphalt area of ​​the specimen as a whole. Figure 3 As an example, three core samples were measured for pure asphalt areas. Measurement images were selected from each specimen at equal intervals from top to bottom. Five images were taken for each specimen, and a total of 15 images were selected, resulting in more than 5,000 data points. The overall pure asphalt area distribution range mainly fluctuated between 8 and 27 μm.

[0062] Next, the distribution range of the asphalt mortar is determined based on the distribution of the aggregates of 0.075 mm and below screened in step S1, and the distribution of the asphalt mortar after three-dimensional reconstruction is measured using the Avizo software. Figure 4 As shown in Figure 2, the three-dimensional reconstructed specimen was then divided into four equal parts, and the distribution range of the asphalt mortar was measured, as shown in Figure 2. Figure 5 As shown in the figure, the measured asphalt mortar distribution thickness data is analyzed to obtain the distribution range of the mortar thickness in the interface area as shown in the figure. Figure 6 As an example, three core samples were measured and it was found that the overall interface mortar thickness distribution range was mainly concentrated between 40-80μm.

[0063] Specifically, the analysis method is to statistically analyze a large amount of thickness range data. For the thickness of the pure asphalt area with smaller data discreteness, the proportion of the pure asphalt area distribution thickness is calculated, and the thickness with a proportion of more than 5% is taken as the thickness range of the pure asphalt area. For the thickness of the mortar area and the mortar area with larger data discreteness, the minimum and maximum values ​​of the entire data set are taken as the thickness range of the area; the three-dimensional reconstructed specimen is divided into four parts for measurement, and from top to bottom, 25%, 50%, 75% and 100% of the volume of the reconstructed specimen are measured respectively.

[0064] Next, in the same way as the 3D reconstruction of asphalt mortar, the distribution range of the specimen mortar was 3D reconstructed by aggregate size screening, such as Figure 7As shown, the distribution range of the mortar is measured by the measurement function of the Avizo software in the same way of four equal divisions. The distribution range of the mortar is obtained by measuring the thickness of the mortar of the specimen after three-dimensional reconstruction. The overall distribution of the mortar thickness data of the specimen is shown in the 8-box line diagram. As an example, it is concluded that the distribution range of the mortar area is between 300μm and 1360μm.

[0065] The inventors have found that the uneven distribution of asphalt on the aggregate surface and the influence of mineral powder contained in asphalt on asphalt density will affect the division range of the previous three-level dispersion system, that is, the adsorption of asphalt by the aggregate surface morphology will affect the division range of the previous three-level dispersion system.

[0066] To this end, the present invention also includes an S3 step for correcting the division range of the three-level dispersion system in the interface area: the aggregate of the asphalt mixture specimen is organically washed, filtered and dried, and the total mass of the asphalt is weighed, the effect of the aggregate surface morphology on the adsorption of asphalt is considered, and then the equivalent asphalt content is calculated to correct the division range of the three-level dispersion system in the interface area.

[0067] The specific correction process is:

[0068] First, the aggregate is washed multiple times with an organic solvent, and then the washed asphalt solution is filtered, and then the filtrate is vacuum filtered. After the filtration is completed, the aggregate on the filter paper is dried and weighed to obtain the total mass of the asphalt;

[0069] Next, considering the influence of asphalt adsorbed on the aggregate surface on asphalt thickness, the mass of asphalt absorbed by the aggregate surface morphology was calculated by referring to the calculation formula (2) for the proportion of asphalt binder absorbed by aggregate in asphalt mixture;

[0070] M 吸附 =M 洗涤后 ×P ba (2)

[0071] Among them, M 吸附 Indicates the mass of asphalt absorbed by the aggregate surface morphology, M 洗涤后 It represents the mass of coarse aggregate after repeated washing, except for surface fine aggregate and asphalt, P ba Indicates the proportion of asphalt absorbed by aggregate;

[0072] The asphalt content attached to the aggregate in the asphalt mortar is calculated by calculating the equivalent asphalt content. The asphalt adsorbed on the aggregate surface and the asphalt attached to the aggregate in the asphalt mortar are comprehensively considered, and the mass of the two is taken out from the total asphalt mass to calculate the asphalt content in the interface transition zone.

[0073] Then, the volume of asphalt is calculated by the asphalt content and density on the aggregate surface, the volume of mineral powder is calculated by the mass and density of mineral powder, and the mixed density of asphalt on the coarse aggregate surface is calculated by the mass of asphalt and mineral powder;

[0074] Finally, the volume is calculated based on the asphalt content and mixed density of the interface transition zone, and then the thickness range of the interface transition zone is calculated based on the surface area. At the same time, the thickness of the asphalt mortar area is corrected based on the pure asphalt area range calculated in step S2.

[0075] The present invention innovatively proposes a method for defining a multi-level dispersion system of asphalt mixtures, and uses a three-dimensional reconstruction model constructed by using specimen slices scanned by industrial CT to propose a new definition of a cross-scale multi-level three-level dispersion system of asphalt mixtures, solving the problem of the lack of a definition standard for a cross-scale multi-level dispersion system of asphalt mixtures. The present invention provides a theoretical premise for accurately predicting the deterioration evolution law of asphalt concrete, which is of great significance for studying the durability of asphalt mixtures.

[0076] The steps for calculating the equivalent asphalt content are as follows: the asphalt in the asphalt mixture is divided into effective asphalt and asphalt adsorbed by mineral aggregates. The effective asphalt content in the asphalt mixture and the 0.075 mm passing rate (P 0.075 The ratio of the powder-binder ratio (FB) is based on the principle that the asphalt content adsorbed by the asphalt mortar mineral material is consistent with the powder-binder ratio. 0.075 It is replaced by the 0.075mm pass rate in the asphalt mortar to obtain the asphalt content attached to the aggregate in the asphalt mortar.

[0077] As an example, the following aggregate surface modified asphalt thickness distribution statistics are obtained:

[0078]

[0079] In summary, the thickness range of the corrected interface transition zone is 34-129μm, with an average value of 82μm. Based on the average value of 15μm of the pure asphalt area of ​​the interface calculated previously, the average value of the asphalt mortar area is 67μm, which verifies that the test results are close to the asphalt mortar area range data obtained by dividing under S2 three-dimensional reconstruction.

[0080] The present invention comprehensively considers the uneven distribution of asphalt on the aggregate surface and the problem that the actual density is not the pure asphalt density due to the mineral powder contained in the asphalt. It also considers the effect of the aggregate surface morphology on the adsorption of asphalt. The volume is calculated by calculating the equivalent asphalt content and the mixed density, and then the thickness range of the interface transition zone is obtained by combining the surface area calculation. Since the effect of the aggregate surface morphology on the adsorption of asphalt will not affect the division result of the pure asphalt area, after the overall correction of the interface transition zone, the asphalt mortar area is specifically corrected according to the average value.

[0081] In order to verify the accuracy of the method of the present invention, micromechanical analysis, micromorphology and chemical properties of the interface area, organic washing of aggregates and particle size analysis were carried out to verify the reliability of the division range of the three-level dispersion system;

[0082] Firstly, the micromechanical analysis of the pure asphalt area at the asphalt mixture interface was performed using a nanoindenter.

[0083] Use epoxy resin to cure the cored sample, then grind the cured sample to polish it. As an example, first use a lower-grit sandpaper to expose the test surface of the sample, then use a higher-grit sandpaper to grind step by step. The grits of the sandpaper are 180, 400, 600, 800, 1200, 2500, and 5000. Finally, use 10,000-grit abrasive paste to polish the surface of the specimen. During the grinding of the specimen, ultrasonic cleaning is performed to remove tiny particles on the surface. Finally, the completed specimen is sealed and stored.

[0084] Conduct nanoindentation test. As an example, select the aggregate and asphalt mortar area for dot test. The dot matrix is ​​a 3×11 matrix with a matrix spacing of 25μm. Dots are placed starting from the lower left corner and increasing to the right from 00000 to 00011. After the dot is completed, move up 25μm and then dot from left to right, and continue in sequence until the end.

[0085] The elastic modulus of each indentation is calculated using the Oliver-Pharr method, and the elastic modulus changes of the indentation are analyzed to determine the pure asphalt area. Fig. 9 .

[0086] Next, the microscopic morphology and chemical properties of the pure asphalt area at the interface were studied. The aggregate interface area was scanned at different magnifications using a scanning electron microscope (SEM), and the microscopic morphology of the area was explored. The interface aggregate and mortar area was selected for line scanning. Through the specific changes in the number of elements, we mainly focused on the regional range of the reduction of silicon and oxygen elements in the aggregate and the increase of carbon elements in the asphalt, and defined the thickness of the pure asphalt area between the aggregate and the asphalt mortar.

[0087] Next, the asphalt and fine aggregate on the aggregate surface are extracted, and the asphalt in the naturally attached state on the aggregate surface is dissolved and washed using an organic solvent. The washed asphalt solution is filtered through a filtering device, the aggregate on the filter paper is dried and weighed, and the mass of the asphalt on the aggregate surface is calculated.

[0088] The three-dimensional morphology of the aggregate is obtained to obtain the aggregate surface area. Combined with the quality of the asphalt on the aggregate surface, the distribution thickness of the asphalt on the aggregate surface is calculated based on the principle of assumed uniformity, and combined with the results of the pure asphalt area verification, the mortar area is obtained.

[0089] Through the division of pure asphalt area and mortar area by S2, we get the thickness of this area is between 8μm-25μm, and the thickness of asphalt mortar area is between 30μm-108μm. By combining the statistical data of the two parts of the area, we can get the thickness of the aggregate interface transition zone is between 38μm-133μm. The statistical range of the data obtained based on the three-dimensional virtual reconstruction division and the verification experiment is relatively close. At the same time, based on the statistics of a large amount of data in the aggregate pure asphalt area based on Avizo software, the average thickness is 15μm, and the average thickness of the asphalt mortar area is 66μm. In terms of average distribution thickness, the results of the asphalt mortar area division show good consistency with the data of this verification experiment.

[0090] The above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for defining a multi-stage dispersion system of an asphalt mixture, characterized in that: The steps include: S1: Collect slice scanning images of asphalt mixture specimens, perform three-dimensional reconstruction on the slice scanning images, and screen out aggregates of different particle sizes; S2: Using the three-dimensional reconstruction model obtained in S1, the interface area is divided into a three-level dispersion system, the interface area is divided into an interface transition area and an asphalt mortar area, and the interface transition area is divided into a pure asphalt area and a mortar area; The measurement function of Avizo software is used to measure the distribution thickness of the pure asphalt area. The distribution interval of the data range of the measured pure asphalt area distribution thickness is summarized and analyzed to obtain the overall pure asphalt area range of the specimen. The distribution range of the asphalt mortar is determined by combining the distribution of the aggregates of 0.075 mm and below screened in step S1. The asphalt mortar distribution range of the three-dimensional reconstructed specimen is then divided into four parts using Avizo software for measurement. The data is analyzed to obtain the distribution range of the mortar thickness in the interface area. The distribution range of the specimen mortar is obtained in the same way as the asphalt mortar. S3: The aggregate of the asphalt mixture specimen is organically washed, filtered and dried, and the total mass of the asphalt is weighed. Considering the effect of the aggregate surface morphology on the adsorption of asphalt, the equivalent asphalt content is calculated and the division range of the three-level dispersion system in the interface area is corrected.

2. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 1, characterized in that: The specific process of step S3 is: First, the aggregate is washed multiple times with an organic solvent, and then the washed asphalt solution is filtered, and then the filtrate is vacuum filtered. After the filtration is completed, the aggregate on the filter paper is dried and weighed to obtain the total mass of the asphalt; Next, considering the influence of asphalt adsorbed on the aggregate surface on asphalt thickness, the mass of asphalt absorbed by the aggregate surface morphology was calculated by referring to the calculation formula (2) for the proportion of asphalt binder absorbed by aggregate in asphalt mixture; M 吸附 =M 洗涤后 ×P ba (2) Among them, M 吸附 Indicates the mass of asphalt absorbed by the aggregate surface morphology, M 洗涤后 It represents the mass of coarse aggregate after repeated washing, except for surface fine aggregate and asphalt, P ba Indicates the proportion of asphalt absorbed by aggregate; The asphalt content attached to the aggregate in the asphalt mortar is calculated by calculating the equivalent asphalt content. The asphalt adsorbed on the aggregate surface and the asphalt attached to the aggregate in the asphalt mortar are comprehensively considered, and the mass of the two is taken out from the total asphalt mass to calculate the asphalt content in the interface transition zone. Then, the volume of asphalt is calculated by the asphalt content and density on the aggregate surface, the volume of mineral powder is calculated by the mass and density of mineral powder, and the mixed density of asphalt on the coarse aggregate surface is calculated by the mass of asphalt and mineral powder; Finally, the volume is calculated based on the asphalt content and mixed density of the interface transition zone, and then the thickness range of the interface transition zone is calculated based on the surface area. At the same time, the thickness of the asphalt mortar area is corrected based on the pure asphalt area range calculated in step S2.

3. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 2, characterized in that: The steps for calculating the equivalent asphalt content are as follows: the asphalt in the asphalt mixture is divided into effective asphalt and asphalt adsorbed by mineral aggregates, and the effective asphalt content in the asphalt mixture and the 0.075 mm passing rate P in the mineral aggregate gradation are calculated. 0.075 The ratio of powder to glue ratio FB is based on the principle that the asphalt content adsorbed by the asphalt mortar mineral material is consistent with the powder to glue ratio. 0.075 It is replaced by the 0.075mm pass rate in the asphalt mortar to obtain the asphalt content attached to the aggregate in the asphalt mortar.

4. The method for defining a multi-stage dispersion system of an asphalt mixture according to any one of claims 1 to 3, characterized in that: Step S1 includes the following steps: S11: providing a rutting plate specimen, and taking a core at an interface area of ​​the specimen; S12: Scan the core specimen using nano-industrial CT to obtain a CT scan image of the specimen slice; S13: using image processing software to export the raw format image file reconstructed from the CT scan into a single slice image file; S14: Use digital image processing technology to process slice images and accurately study the distribution characteristics of the microstructure of the asphalt mixture interface area; S15: performing threshold segmentation on the segmented image processed by the digital image processing technology and reconstructing the three-dimensional visualization of the coring specimen; S16: Separate the aggregates of the reconstructed specimen, obtain the volume characteristic parameters of each aggregate, extract the volume information of the aggregate, calculate the corresponding equivalent diameter according to the volume equality principle, and screen the aggregates of different particle sizes according to the particle size information of the aggregates to complete the three-dimensional reconstruction of the aggregates of different particle sizes; wherein, The screening principle of aggregates with different particle sizes is: particle sizes of 0-0.075mm are divided into one group, which is the distribution of asphalt mortar filler; particle sizes of 0.075mm-2.36mm are divided into one group, which is the distribution of asphalt mortar fine aggregate; finally, particle sizes above 2.36 are used as coarse aggregate.

5. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: Digital image processing technology is an image segmentation technology based on deep learning network model.

6. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: The 3D visualization of the reconstructed specimens was achieved using Avizo software.

7. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: The formula for calculating equivalent diameter based on the volume equality principle is: Where V represents the volume of aggregate and D represents the particle size of aggregate.

8. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: For the thickness of pure asphalt areas with smaller data discreteness, the proportion of pure asphalt area distribution thickness is calculated, and the thickness with a proportion exceeding 5% is taken as the thickness range of the pure asphalt area. For the thickness of mortar areas and mortar areas with larger data discreteness, the minimum and maximum values ​​of the entire data set are taken as the thickness range of the area.

9. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: From top to bottom, 25%, 50%, 75% and 100% of the volume of the reconstructed specimen were measured.

10. The method for defining a multi-stage dispersion system of asphalt mixture according to claim 4, characterized in that: The process of obtaining asphalt quality includes: washing the aggregate with an organic solvent multiple times, filtering the washed asphalt solution through a filtration device, and vacuum filtering the filtrate with a suction pump. After the filtration is completed, the aggregate on the filter paper is dried and weighed using a high-precision electronic scale.

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