Method for determining the optimal fiber length in chopped fiber modified EA-10 epoxy asphalt mixture

Abstract

The present invention discloses a method for determining the optimal length of fibers in EA-10 epoxy asphalt mixture modified with short fibers. The method comprises the following steps: performing a mix design on the EA-10 epoxy asphalt mixture, calculating the gradation parameters of the EA-10 epoxy asphalt mixture of short fibers, constructing a discrete element model based on the gradation parameters, performing a binarization process on the model, extracting the microscopic characteristic parameters of the EA-10 epoxy asphalt mixture, and finally performing a statistical process to determine the optimal length of the short fibers in the EA-10 epoxy asphalt mixture modified with short fibers based on the microscopic characteristic parameters. The present invention can effectively determine the optimal length of fibers in the EA-10 epoxy asphalt mixture modified with short fibers, solves the problem that the test results of the traditional macroscopic indoor test method for determining the optimal length of fibers are highly discrete, saves raw materials and test costs, and lays a foundation for determining the admixture ratio of mixed-length fibers in the EA-10 epoxy asphalt mixture modified with short fibers.

Description

Technical Field

[0001] The present invention relates to the field of road engineering materials, and in particular to a method for determining the optimal fiber length in chopped fiber-modified EA-10 epoxy asphalt mixture. Background Art

[0002] In recent years, the improvement of the road performance of asphalt mixtures by fibers has attracted widespread attention from scholars. Fibers can play a role in the reinforcement, strengthening, and crack resistance of the mixture, and have become one of the mainstream development directions of asphalt pavement materials both domestically and internationally. Epoxy asphalt, as a new road material, outperforms conventional asphalt mixtures. However, epoxy asphalt mixtures also have some shortcomings, such as poor low-temperature performance and insufficient water stability and durability. Therefore, the addition of chopped fibers to epoxy asphalt mixtures can significantly improve their road performance, making them suitable for platforms with higher strength requirements. At the same time, relevant research has shown that the effects of chopped fibers of different lengths on the road performance of epoxy asphalt mixtures vary significantly.

[0003] Numerous studies have shown that, at the same dosage, chopped fiber length is a significant factor influencing the performance enhancement of asphalt mixtures. Due to the wide variety of chopped fiber types and the fact that actual chopped fiber production typically uses lengths in multiples of three, there is currently no effective method for determining the optimal fiber length for chopped fiber-modified EA-10 epoxy asphalt mixtures. Determining the optimal fiber length for chopped fiber-modified EA-10 epoxy asphalt mixtures is crucial for maximizing the fiber's reinforcing effect.

[0004] Through investigation, it was found that the determination of the optimal fiber length in chopped fiber modified EA-10 epoxy asphalt mixture at home and abroad basically adopts the enumeration method. By designing a large number of experimental groups to obtain material properties and conduct comparative optimization, the following problems mainly exist:

[0005] 1. The macro-experimental process is complex, time-consuming and labor-intensive, and the economic investment and results are not cost-effective;

[0006] 2. There are many types of fibers and specifications for chopped fiber lengths. It is difficult for the test method to exhaust all combinations. The combinations determined are only those with better results among the enumeration.

[0007] Therefore, how to avoid a large number of macroscopic tests and accurately, efficiently and conveniently determine the optimal fiber length in chopped fiber-modified EA-10 epoxy asphalt mixture to maximize the reinforcing effect of chopped rock fiber is an urgent problem to be solved. Summary of the Invention

[0008] To meet the needs of engineering and experiments, the present invention proposes a method for determining the optimal fiber length in chopped fiber-modified EA-10 epoxy asphalt mixture. This method has low cost, simple operation, and high efficiency, and greatly enriches the application of discrete element simulation technology in the selection of chopped fiber length.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for determining the optimal fiber length in a chopped fiber-modified EA-10 epoxy asphalt mixture comprises the following steps:

[0011] S1, design the mix ratio of EA-10 short fiber epoxy asphalt mixture and calculate the gradation parameters of EA-10 short fiber epoxy asphalt mixture;

[0012] S2, using the gradation parameters to write a discrete element simulation code to generate a discrete element model of EA-10 epoxy asphalt mixture;

[0013] S3, binarize the discrete element model of EA-10 epoxy asphalt mixture and use image processing software to extract the microscopic characteristic parameters of EA-10 epoxy asphalt mixture;

[0014] S4, statistically process the microscopic characteristic parameters of EA-10 epoxy asphalt mixture to determine the optimal length of chopped fibers added to the chopped fiber modified EA-10 epoxy asphalt mixture.

[0015] Preferably, in step S1, the gradation parameters of EA-10 epoxy asphalt mixture include the volume v of each grade of coarse and fine aggregates Di and aggregate void ratio VMA, assuming asphalt density is ρ a , the density of coarse and fine aggregates are both ρ b , the total volume of the asphalt mixture specimen is V, the designed void ratio is VV, the volume of coarse and fine aggregates is v, and the asphalt-stone ratio is α. Then the void ratio of the mineral aggregate is the proportion of the part other than coarse and fine aggregates in the specimen:

[0016]

[0017] The particle sizes of coarse and fine aggregates are D1, D2, D3, ...D i ,…D n , n is the number of grades, and the passing rate of each grade is 100%, P D2 、P D3 ,…P Di ,…,P Dn According to the results of each parameter, the volume v of each grade of coarse and fine aggregate can be calculated Di :

[0018]

[0019] Preferably, in step S1, a mix ratio design is performed for the EA-10 chopped fiber epoxy asphalt mixture, wherein the coarse aggregate is the aggregate with a particle size greater than 1.18 mm and less than 13.2 mm, and the fine aggregate is the aggregate with a particle size greater than 0 mm and less than 1.18 mm.

[0020] Preferably, in step S2, the software used to construct the discrete element model is PFC 2D software, and the generated EA-10 epoxy asphalt mixture discrete element model is a two-dimensional mineral aggregate distribution microscopic model of EA-10 epoxy asphalt mixture, whose components are the wall, each grade of coarse and fine aggregates, and mineral aggregate gaps. The specific construction process is as follows:

[0021] (1) Define the calculation area and generate the wall: Before performing the numerical simulation calculation, the calculation area must be defined and the wall must be generated at the boundary of the area. In order to ensure that the coarse and fine aggregate particles generated subsequently can be fully and randomly distributed in the wall, the initial calculation area and wall size are generally set to two to three times the size of the asphalt mixture specimen. In order to ensure the accuracy of the microscopic characteristic parameters obtained subsequently, the final width of the EA-10 epoxy asphalt mixture discrete element model wall should be greater than 5 times the maximum sieve hole passing particle size;

[0022] (2) Generation of coarse and fine aggregate particles: The volume v of each grade of coarse and fine aggregate is calculated from the gradation parameters. Di Then, the PFC 2D software is used to generate coarse and fine aggregate particle groups in the selected calculation area through command flow, so that the volume and v of all coarse and fine aggregate particles in the file are accumulated each time coarse and fine aggregate particles are generated. Di’ , if v Di’ <v Di , then return to the previous step and continue to randomly generate the coarse and fine aggregate particles of this file. If v Di’ ≥v Di , then stop generating the coarse and fine aggregate particles of this level, output the results, and generate the next level of coarse and fine aggregate particles. After running the command stream multiple times, a group of coarse and fine aggregate particles with gradation characteristics can be generated;

[0023] (3) Generation of mineral gaps: Use PFC 2D software to characterize porosity with mineral gap ratio, so that the generated mineral gaps meet the grading parameter requirements;

[0024] (4) Gravity fall and wall compaction molding: In step (1), in order to make the coarse and fine aggregate particle groups generated have a fully random spatial distribution, the height of the rectangular specimen is expanded to twice. After the coarse and fine aggregate particle groups are generated, the specimen is compacted by its own gravity free fall and the top wall until the top wall drops to the specified height of the specimen.

[0025] Preferably, in step S3, binarization of the discrete element model of EA-10 epoxy asphalt mixture refers to separating the "coarse and fine aggregates" and "mineral gaps" in the model based on the threshold segmentation method, selecting bimodal threshold segmentation, and bimodal threshold segmentation based on the peak interval in the grayscale histogram of coarse and fine aggregates and mineral gaps to convert the image with grayscale values ​​distributed between 0 and 255 into a binary image with grayscale values ​​of 0 or 255.

[0026] Specifically, in step S3, image pro plus image processing software is used to extract the microscopic characteristic parameters of EA-10 epoxy asphalt mixture, wherein the microscopic characteristic parameter of EA-10 epoxy asphalt mixture is the longest axis of the mineral aggregate gap, and the longest axis of the mineral aggregate gap is the longest axis among the gaps formed by the contact of coarse and fine aggregates in the asphalt mixture.

[0027] Preferably, in step S4, the mesoscopic characteristic parameters of the EA-10 epoxy asphalt mixture are statistically processed. The statistical processing refers to analyzing the obtained mesoscopic parameters of the EA-10 epoxy asphalt mixture, and characterizing the optimal length of the added chopped fibers by the length determined by the length interval with the highest distribution frequency of the mesoscopic parameters. Specifically, the statistical processing includes the following steps:

[0028] (1) Arrange the extracted microscopic characteristic parameters in ascending order: the longest axis of the mineral gap;

[0029] (2) Count the number of longest axes of the mineral gaps in the intervals (0, 1), [1, 2), [2, 3), ..., [n, +∞), and denote them as X1, X2, ..., X i , i is an integer from 1 to n;

[0030] (3) Determine the maximum value of Xi Max(Xi);

[0031] (4) Determine the optimal length gradation of basalt fiber: If the maximum value of Xi Max (X i )=X6, then the optimal length grade of the chopped fiber is L=6mm; if the maximum value of XiMax(X i )=X9, then the optimal length grade of the chopped fiber is L=9mm.

[0032] Compared with the prior art, the present invention has the following benefits:

[0033] 1. The method for determining the optimal fiber length in the chopped fiber modified EA-10 epoxy asphalt mixture provided by the present invention avoids the complicated process of macroscopic testing and the discreteness of the test results, has high efficiency, and avoids the waste of manpower and material resources.

[0034] 2. The method for determining the optimal fiber length in the chopped fiber modified EA-10 epoxy asphalt mixture provided by the present invention can be applied to different types of chopped fibers, avoiding repeated experiments, and has strong operability and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the implementation process of the method for determining the optimal fiber length in the chopped fiber modified EA-10 epoxy asphalt mixture provided by the present invention.

[0036] Figure 2 It is a binarized image of the discrete element microscopic model of EA-10 epoxy asphalt mixture provided in the embodiment.

[0037] Figure 3 1 is a frequency diagram of the longest axis length distribution of the gap between the EA-10 epoxy asphalt mixture mineral materials provided in the embodiment. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described in more detail below in conjunction with specific embodiments:

[0039] Figure 1 The figure is a schematic diagram of the implementation process of the method for determining the optimal fiber length in the chopped fiber modified EA-10 epoxy asphalt mixture provided by the present invention. The method includes the following steps:

[0040] Step 1: Design the mix ratio of EA-10 chopped fiber epoxy asphalt mixture and calculate the gradation parameters of EA-10 chopped fiber epoxy asphalt mixture. The gradation parameters of EA-10 epoxy asphalt mixture include the volume v of each grade of coarse and fine aggregates. Di and aggregate void ratio VMA, assuming asphalt density is ρ a , the density of coarse and fine aggregates are both ρ b (In practice, the density of coarse aggregate and fine aggregate is different, but in the simulation, their density values ​​are recorded as the same size, both ρ b ), the total volume of the asphalt mixture specimen is V, the designed void ratio is VV, the volume of coarse and fine aggregates is v, and the asphalt-stone ratio is α. The aggregate void ratio VMA is the proportion of the part other than coarse and fine aggregates in the specimen:

[0041]

[0042] The particle sizes of coarse and fine aggregates are D1, D2, D3, ...D i ,…D n , n is the number of grades, and the passing rate of each grade is 100%, P D2 、P D3 ,…P Di ,…,P Dn According to the results of each parameter, the volume v of each grade of coarse and fine aggregate can be calculatedDi :

[0043]

[0044] Step 2: Use the gradation parameters to write a discrete element simulation code to generate the EA-10 epoxy asphalt mixture discrete element model (EA-10 epoxy asphalt mixture two-dimensional mineral distribution micro-model). The discrete element model generation steps include defining the calculation area and generating the wall, generating coarse and fine aggregate particles, generating mineral gaps, and compacting the wall. The specific generation process is as follows:

[0045] (1) Define the calculation area and generate the wall: Before performing the numerical simulation calculation, the calculation area must be defined and the wall must be generated at the boundary of the area. In order to ensure that the coarse and fine aggregate particles generated subsequently can be fully and randomly distributed in the wall, the initial calculation area and wall size are generally set to two to three times the size of the asphalt mixture specimen. In order to ensure the accuracy of the microscopic characteristic parameters obtained subsequently, the final width of the EA-10 epoxy asphalt mixture discrete element model wall should be greater than 5 times the maximum sieve hole passing particle size.

[0046] (2) Generation of coarse and fine aggregate particles: The volume v of each grade of coarse and fine aggregate is calculated from the gradation parameters. Di Then, the PFC 2D software is used to generate coarse and fine aggregate particle groups in the selected calculation area through command flow, so that the volume and v of all coarse and fine aggregate particles in the file are accumulated each time coarse and fine aggregate particles are generated. Di’ , if v Di’ <v Di , then return to the previous step and continue to randomly generate the coarse and fine aggregate particles of this file. If v Di’ ≥v Di , then stop generating the coarse and fine aggregate particles of this level, output the results, and generate the next level of coarse and fine aggregate particles. After running the command stream multiple times, a group of coarse and fine aggregate particles with grading characteristics can be generated.

[0047] (3) Generation of mineral gaps: Use PFC 2D software to characterize porosity with mineral gap ratio so that the generated mineral gaps meet the grading parameter requirements.

[0048] (4) Gravity drop and wall compaction: In step (1), to ensure that the coarse and fine aggregate particles are fully randomly distributed, the height of the rectangular specimen is doubled. After the coarse and fine aggregate particles are generated, the specimen is compacted by gravity free fall and the top wall until the top wall descends to the specified height of the specimen.

[0049] Step 3: Binarize the EA-10 epoxy asphalt mixture discrete element mesoscopic model using bimodal threshold segmentation to separate the "aggregate" and "mineral gaps" in the model. Bimodal threshold segmentation selects an appropriate threshold based on the peak intervals in the grayscale histograms of aggregate and mineral gaps. This converts an image with grayscale values ​​ranging from 0 to 255 into a binary image with grayscale values ​​of 0 or 255. Image processing software is used to extract the mesoscopic characteristic parameters of the epoxy asphalt mixture.

[0050] Step 4: Statistically process the microscopic characteristic parameters to determine the optimal fiber length in the chopped fiber modified EA-10 epoxy asphalt mixture. This specifically includes the following steps:

[0051] (1) Arrange the extracted microscopic characteristic parameters in ascending order: the longest axis of the mineral gap;

[0052] (2) Count the number of longest axes of the mineral gaps in the intervals (0, 1), [1, 2), [2, 3), ..., [n, +∞), and denote them as X1, X2, ..., X i , i is an integer from 1 to n;

[0053] (3) Determine the maximum value of Xi Max(Xi);

[0054] (4) Determine the optimal length gradation of basalt fiber: If the maximum value of Xi Max (X i )=X6, then the optimal length grade of the chopped fiber is L=6mm; if the maximum value of XiMax(X i )=X9, then the optimal length grade of the chopped fiber is L=9mm.

[0055] Example 1

[0056] The mix ratio design of EA-10 epoxy asphalt mixture was carried out and the gradation parameters of EA-10 epoxy asphalt mixture were calculated: coarse and fine aggregates of different particle size ranges were divided into different grades according to the specifications. Based on the mix ratio design results, the volume of coarse and fine aggregates and the void ratio of mineral aggregates in each grade were calculated. The particle size of coarse aggregate is 1.18mm to 13.2mm, the particle size of fine aggregate is 0.075mm to 1.18mm, and the density of asphalt is ρ a =1.038g / cm 3 , the density of coarse and fine aggregates are both ρ b =2.7g / cm 3 The total volume of the asphalt mixture specimen is V = 70 × 125 = 8750 mm 3 , the designed void ratio is VV = 4%, the volume of coarse and fine aggregates is v, and the oil-stone ratio is α = 7.7%. Then the void ratio of the mineral aggregate is the proportion of the part other than coarse and fine aggregates in the specimen:

[0057]

[0058] The particle sizes of coarse and fine aggregates are D1, D2, D3, ...D i ,…D n , n is the number of grades, and the passing rate of each grade is 100%, P D2 、P D3 ,…P Di ,…,P Dn According to the results of each parameter, the volume v of each grade of coarse and fine aggregate can be calculated Di As shown in Table 1:

[0059] Table 1 Volume of coarse and fine aggregates of different grades

[0060] Particle size / mm 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 0 Pass rate / % 100 98.7 74.5 59.2 47.5 32.5 20.8 15.9 12.4 0 Grading sieve residue / % 0 1.3 24.2 15.3 11.7 15 11.7 4.9 3.5 12.4 <![CDATA[Volume / mm 3 > 0 113.8 2117.5 1338.8 1487.5 1312.5 1023.8 428.8 306.3 1085

[0061] Use the gradation parameters to write a discrete element simulation code to generate the discrete element model of EA-10 epoxy asphalt mixture. The components of the discrete element model of EA-10 epoxy asphalt mixture are the wall, the coarse and fine aggregates of each grade, and the gaps between the mineral aggregates. The specific simulation process is as follows:

[0062] (1) Define the calculation area and generate the wall: Before performing numerical simulation calculations, the calculation area must be defined and the wall generated at the area boundary. To ensure that the aggregate particles generated subsequently can be fully and randomly distributed in the wall, the initial calculation area and wall size are set to twice the size of the asphalt mixture specimen. To ensure the accuracy of the subsequently obtained microscopic characteristic parameters, the wall size of the EA-10 epoxy asphalt mixture discrete element model should be 70 mm × 125 mm.

[0063] (2) Generation of coarse and fine aggregate particles: The volume v of each grade of coarse and fine aggregate is calculated from the gradation parameters. Di Then, the PFC 2D software is used to generate coarse and fine aggregate particle groups in the selected calculation area through command flow, so that the volume and v of all coarse and fine aggregate particles in the file are accumulated each time coarse and fine aggregate particles are generated. Di’ , if v Di’ <v Di , then return to the previous step and continue to randomly generate the coarse and fine aggregate particles of this file. If v Di’ ≥v Di , then stop generating the coarse and fine aggregate particles of this level, output the results, and generate the next level of coarse and fine aggregate particles. After running the command stream multiple times, a group of coarse and fine aggregate particles with grading characteristics can be generated.

[0064] (3) Generation of mineral gaps: PFC 2D software was used to characterize the porosity with a mineral gap ratio of 15.3%, so that the generated mineral gaps met the grading parameter requirements.

[0065] (4) Gravity drop and wall compaction: In step (1), to ensure that the coarse and fine aggregate particles are fully randomly distributed, the height of the rectangular specimen is doubled. After the coarse and fine aggregate particles are generated, the specimen is compacted by gravity free fall and the top wall until the top wall descends to the specified height of the specimen.

[0066] Based on the EA-10 epoxy asphalt mixture discrete element microscopic model, the binary processing is performed and the bimodal threshold segmentation is selected to separate the "aggregate" and "mineral gap" in the model. Figure 2 The image processing software Image-Pro-Plus (IPP) was used to extract the longest axis parameters of the mineral gap of EA-10 epoxy asphalt mixture, export the data, and generate an EXCEL table.

[0067] According to statistical processing, the optimal length of chopped fibers was determined: the longest axes of the microscopic mineral gaps were extracted in ascending order, and the longest axes of the mineral gaps were statistically distributed in the intervals (0, 1), [1, 2), [2, 3), ..., [9, +∞), with the proportions being X1 = 11.4%, X2 = 13.4%, X3 = 26.8%, X4 = 17.8%, X5 = 9.3%, X6 = 8.6%, X7 = 6.7%, X8 = 3.3%, and X9 = 2.7%, respectively. The distribution frequency diagram is shown in the figure below. Figure 3 As shown, we can see that the maximum value of Xi Max (X i )=X3, then the optimal length of the chopped fiber is L=3mm.

[0068] The chopped fiber length was 3 mm, the type of chopped fiber was basalt fiber, the total fiber content was 0.3% of the total mass of the asphalt mixture, and the optimal oil-stone ratio was 7.7%. EA-10 basalt fiber epoxy asphalt mixture was prepared. The high-temperature rutting test and low-temperature beam bending test were used to test its high-temperature performance and low-temperature performance, respectively. The results are shown in Tables 2 and 3.

[0069] Comparative Example 1

[0070] The chopped fiber length was selected to be 6 mm, the type of chopped fiber was basalt fiber, the total fiber content was 0.3% of the total mass of the asphalt mixture, and the optimal oil-stone ratio was 7.7%. EA-10 basalt fiber epoxy asphalt mixture was prepared. The high-temperature rutting test and low-temperature beam bending test were used to test its high-temperature performance and low-temperature performance, respectively. The results are shown in Tables 2 and 3.

[0071] Comparative Example 2

[0072] The chopped fiber length was selected as 9 mm, the type of chopped fiber was basalt fiber, the total fiber content was 0.3% of the total mass of the asphalt mixture, and the optimal oil-stone ratio was 7.7%. EA-10 basalt fiber epoxy asphalt mixture was prepared. The high-temperature rutting test and low-temperature beam bending test were used to test its high-temperature performance and low-temperature performance, respectively. The results are shown in Tables 2 and 3.

[0073] Table 2 Comparison of high temperature performance of epoxy asphalt mixtures with different lengths of chopped fibers

[0074]

[0075] Table 3 Comparison of low temperature performance of epoxy asphalt mixture with different lengths of chopped fiber

[0076]

[0077]

Claims

1. A method for determining the optimal fiber length in chopped fiber modified EA-10 epoxy asphalt mixture, characterized in that: The steps include: S1, design the mix ratio of EA-10 short fiber epoxy asphalt mixture and calculate the gradation parameters of EA-10 short fiber epoxy asphalt mixture; S2, using the above gradation parameters to write a discrete element simulation code to generate a discrete element model of EA-10 epoxy asphalt mixture; S3, performing binarization processing on the above discrete element model to extract the microscopic characteristic parameters of EA-10 epoxy asphalt mixture; S4, performing statistical processing on the above microscopic characteristic parameters to determine the optimal length of the chopped fibers to be incorporated into the chopped fiber modified EA-10 epoxy asphalt mixture; Among them, in step S1, the gradation parameters of EA-10 epoxy asphalt mixture include the volume of coarse and fine aggregates v Di and the aggregate void ratio VMA, assuming the asphalt density is ρ a , the density of coarse and fine aggregates is ρ b , the total volume of the asphalt mixture specimen is V, the designed void ratio is VV, the volume of coarse and fine aggregates is v, and the asphalt-stone ratio is α, then the aggregate void ratio VMA is expressed as follows: The particle sizes of coarse and fine aggregates are D1, D2, D3, ...D i ,…D n , n is the number of grades, and the passing rate of each grade is 100%, P D2 、P D3 ,…P Di ,…,P Dn , according to the results of each parameter, the volume v of each grade of coarse and fine aggregate is obtained Di : In step S2, the software used to construct the discrete element model is PFC 2D software. The generated EA-10 epoxy asphalt mixture discrete element model is a two-dimensional mineral aggregate distribution micro-model of EA-10 epoxy asphalt mixture. Its components are the wall, various grades of coarse and fine aggregates, and mineral aggregate gaps. The specific construction process is as follows: (1) Define the calculation area and generate the wall: Before performing the numerical simulation calculation, the calculation area must be defined and the wall must be generated at the boundary of the area. In order to ensure that the coarse and fine aggregate particles generated subsequently can be fully and randomly distributed in the wall, the initial calculation area and wall size are set to two to three times the size of the asphalt mixture specimen. In order to ensure the accuracy of the microscopic characteristic parameters obtained subsequently, the final width of the EA-10 epoxy asphalt mixture discrete element model wall should be greater than 5 times the maximum sieve hole passing particle size; (2) Generation of coarse and fine aggregate particles: The volume v of each grade of coarse and fine aggregate is calculated from the gradation parameters. Di Then, the PFC 2D software is used to generate coarse and fine aggregate particle groups in the selected calculation area through command flow, so that the volume and v of all coarse and fine aggregate particles in the file are accumulated each time coarse and fine aggregate particles are generated. Di ', if v Di '<v Di , then return to the previous step and continue to randomly generate the coarse and fine aggregate particles of this file. If v Di '≥v Di , then stop generating the coarse and fine aggregate particles of this level, output the results, and generate the next level of coarse and fine aggregate particles. After running the command stream multiple times, a group of coarse and fine aggregate particles with gradation characteristics can be generated; (3) Generation of mineral gaps: Use PFC 2D software to characterize porosity with mineral gap ratio, so that the generated mineral gaps meet the grading parameter requirements; (4) Gravity fall and wall compaction molding: In step (1), in order to make the coarse and fine aggregate particle groups generated have a fully random spatial distribution, the height of the rectangular specimen is expanded to twice. After the coarse and fine aggregate particle groups are generated, the specimen is compacted by its own gravity free fall and the top wall until the top wall drops to the specified height of the specimen.

2. The method according to claim 1, wherein In step S1, a mix ratio design is performed for the EA-10 chopped fiber epoxy asphalt mixture, wherein the coarse aggregate is the aggregate with a particle size greater than 1.18 mm and less than 13.2 mm, and the fine aggregate is the aggregate with a particle size greater than 0 mm and less than 1.18 mm.

3. The method according to claim 1, wherein In step S3, the EA-10 epoxy asphalt mixture discrete element model is binarized. This means that bimodal threshold segmentation is used to separate the "coarse and fine aggregates" and "mineral gaps" in the model based on a threshold segmentation method. The bimodal threshold segmentation selects an appropriate threshold based on the peak interval in the grayscale histogram of the coarse and fine aggregates and the mineral gaps, and converts the image with grayscale values ​​distributed between 0 and 255 into a binary image with grayscale values ​​of 0 or 255.

4. The method according to claim 1, wherein In step S3, image pro plus image processing software is used to extract the microscopic characteristic parameters of the EA-10 epoxy asphalt mixture, wherein the microscopic characteristic parameter of the EA-10 epoxy asphalt mixture is the longest axis of the mineral aggregate gap, and the longest axis of the mineral aggregate gap is the longest axis among the gaps formed by the contact between coarse and fine aggregates in the asphalt mixture.

5. The method according to claim 1, wherein In step S4, the microscopic characteristic parameters of the EA-10 epoxy asphalt mixture are statistically processed. The statistical processing refers to analyzing the obtained microscopic parameters of the EA-10 epoxy asphalt mixture and characterizing the optimal length of the added chopped fibers by the length determined by the length interval with the highest distribution frequency of the microscopic parameters. The statistical processing specifically includes the following steps: (1) Arrange the extracted microscopic characteristic parameters in ascending order: the longest axis of the mineral gap; (2) Count the number of longest axes of the mineral gaps in the interval (0, 1), [1, 2), [2, 3), ..., [n, +∞), and record them as X1, X2, ..., X i , i is an integer from 1 to n; (3) Determine X i Maximum value Max(X i ); (4) Determine the optimal length gradation of basalt fiber: If X i Maximum value Max(X i )=X6, then the optimal length grade of the chopped fiber is L=6mm; if X i Maximum value Max(X i )=X9, then the optimal length grade of the chopped fiber is L=9mm.

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