Evaluation method for viscoelastic cracking performance of rubber asphalt mixture

Abstract

The invention discloses a method for evaluating the viscoelastic cracking performance of a rubber asphalt mixture, and aims to solve the problem that the current evaluation of the cracking performance of the rubber asphalt mixture is only limited to brittle cracking at low temperature and does not relate to the evaluation of the viscoelastic cracking performance. The evaluation method comprises the following steps: 1, cutting a Marshall test piece; 2, image recognition; 3, carrying out an indirect tensile test on the asphalt mixture Marshall test piece, and determining a control load; 4, acquiring a picture of the asphalt mixture in an indirect tensile test loading process; 5, calculating and obtaining a surface strain field of the asphalt mixture Marshall test piece in the indirect tensile test process; 6, calculating a high strain index, and determining a high strain area proportion; 7, calculating a viscoelastic protection index; 8, constructing a discrete element test piece model; ninthly, indirect stretching simulation is carried out; 10, counting a mortar tension chain; 11, calculating a mortar force chain score; and 12, evaluating. According to the method, an image recognition technology and discrete element modeling are combined, so that the accuracy of an evaluation result is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of asphalt mixture evaluation, and in particular relates to a method for evaluating the viscoelastic cracking performance of a rubber asphalt mixture. Background Art

[0002] my country is currently facing the problem of dealing with a large number of waste tires. Making waste rubber tires into rubber powder to prepare rubber asphalt is an effective treatment method. As a typical viscoelastic and temperature-sensitive material, rubber asphalt pavement has real-time large deformation characteristics under the coupling of temperature and load.

[0003] Asphalt mixture is mainly composed of elastic aggregate, viscoelastic asphalt mortar and voids. It is greatly affected by temperature and exhibits viscoelastic plasticity as a whole. Affected by the asphalt content and temperature, the viscoelastic characteristics are uncertain and the overall performance is uncertain. At high temperatures, asphalt is fluid, and practitioners are more concerned about the anti-rutting performance of asphalt mixtures; for the cracking performance of asphalt mixtures, they often focus on brittle cracking at low temperatures. In fact, in the viscoelastic state of asphalt mixtures, adhesion and cohesion damage will occur under large deformation due to external forces, which is specifically manifested as cracking of asphalt mixtures. The viscoelastic cracking phenomenon of rubber asphalt mixtures is more obvious. Practitioners rarely study the viscoelastic cracking of rubber asphalt mixtures.

[0004] The discrete element method (DEM) is a numerical method based on the theory of non-continuous media to simulate the mechanical behavior of granular materials. It is suitable for the micromechanical properties and stress-deformation analysis of bulk or cemented materials, and can quantify the transmission distribution of the internal force chain field of the material during loading. The force exerted on each particle and the displacement generated can be expressed intuitively. The digital speckle correlation method (DIC) can obtain the evolution of the displacement field and strain field of the material surface under load, and can analyze the micro-deformation characteristics of asphalt mixture under loading mode based on the digital speckle method. Therefore, it is of practical application value to use the discrete element method (DEM) and the digital speckle correlation method (DIC) as research methods, and to use the contact force chain field and the micro-deformation field as analysis indicators to evaluate the viscoelastic cracking of asphalt mixture. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that when a rubber asphalt mixture is in a viscoelastic state, it cracks under the action of an external load. The current evaluation of the cracking performance of the rubber asphalt mixture is limited to brittle cracking at low temperatures and does not involve the evaluation of the viscoelastic cracking performance. A method for evaluating the viscoelastic cracking performance of a rubber asphalt mixture is provided.

[0006] The evaluation method of the viscoelastic cracking performance of the rubber asphalt mixture of the present invention is implemented according to the following steps:

[0007] Step 1: cutting the surface of the rubber asphalt mixture Marshall specimen, observing the exposed aggregate in the section of the cut specimen as natural speckle, and obtaining a pre-treated specimen;

[0008] Step 2: Perform image recognition on the cut section of the pre-treated specimen to obtain the aggregate area and the mortar area, respectively, to obtain the pre-treated specimen;

[0009] Step 3: Place the pretreated specimen in a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state, and use a universal testing machine to perform an indirect tensile test on the pretreated specimen to obtain a mechanical loading curve, with 80% of the maximum load as the control load during the digital speckle test;

[0010] Step 4: Put another pre-treated specimen into a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state, and perform an indirect tensile test on the pre-treated specimen using a universal testing machine. When the load reaches the control load, the loading is stopped, and the image of the asphalt mixture specimen during the indirect tensile test is obtained by a digital speckle image acquisition system.

[0011] Step 5, determine the analysis sub-area, and obtain the surface horizontal strain field of the pretreated specimen in step 4 during the indirect tensile test;

[0012] Step 6: Determine the high strain area S from the surface horizontal strain field in step 5 高应变 ;

[0013] Step 7. The calculation formula of viscoelastic protection index D is as follows:

[0014]

[0015] In the formula, S 砂浆 and S 高应变 are the mortar area and high strain area area respectively;

[0016] Step 8: Construct discrete element specimen model:

[0017] Through CT scanning of a single aggregate, templates of aggregates with different shapes are established, and an aggregate shape template library is constructed. Then, a random generation algorithm is used to generate an asphalt mixture specimen model of the corresponding gradation according to the gradation, and the positions of the constituent particles are obtained as the aggregate positions. Aggregate templates in the aggregate shape template library are randomly retrieved to replace the randomly generated particles. The corresponding contact models and mechanical contact parameters of the components' internal and interface are adjusted to ensure that the discrete element model is in a viscoelastic state, and then a discrete element specimen model is constructed.

[0018] Step 9. Build rectangular walls at the top and bottom of the side of the discrete element specimen model. The rectangular walls are all composed of "facets". The top is the loading wall and the bottom is the bearing wall. The speed of the loading wall is controlled to simulate the indirect tensile test. Stop loading when the load reaches the control load determined in step 3.

[0019] Step 10: traverse the force chain information inside the discrete element specimen model when the control load is reached to obtain the tension chain ratio P inside the mortar and at the mortar-aggregate interface;

[0020] Step 11: Calculate the score M, M = 1-P;

[0021] Step 12: The evaluation result of the viscoelastic cracking performance of the asphalt mixture is S, which is calculated according to the following formula (1), thereby completing the evaluation of the viscoelastic cracking performance of the asphalt mixture;

[0022] S = 0.5*D*100+0.5*M*100(1).

[0023] The present invention adopts image recognition technology and discrete element modeling to propose a method for evaluating the viscoelastic cracking performance of rubber asphalt mixture, which provides a research method for facing and paying attention to the viscoelastic cracking phenomenon of asphalt mixture; the phenomenon of viscoelastic cracking of rubber asphalt mixture is shown to exist, but current research only pays attention to low-temperature brittle cracking and high-temperature rutting, resulting in the inability to evaluate viscoelastic cracking, and the phenomenon of cracking of the road surface in a viscoelastic state is ignored. By using digital speckle means and discrete element modeling methods, actual testing is combined with simulation simulation, which effectively solves the problem of difficulty in obtaining actual test data and improves the accuracy of simulation simulation; discrete element modeling proposes that the discrete element geometric specimen model adopts a combination of image processing (aggregate morphology) + random generation (aggregate position), taking into account both efficiency and accuracy; the viscoelastic protection index and the ratio of the tensile chain inside the mortar and the mortar-aggregate interface are proposed, which fully considers the important influence of asphalt mortar on the viscoelastic properties of asphalt mixture, combines actual deformation with mechanical analysis, conforms to the actual characteristics of viscoelastic cracking, and effectively improves the accuracy of the evaluation results. A corresponding evaluation method for the viscoelastic cracking performance of asphalt mixtures is proposed, which is in line with the current status of asphalt pavement use and is helpful for the evaluation of asphalt mixture performance and design guidance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the image recognition diagram of the Marshall specimen of asphalt mixture in Example 1;

[0025] Figure 2 The surface horizontal strain field during the indirect tensile test under controlled load in Example 1;

[0026] Figure 3 This is a test diagram of the discrete element specimen model in step nine of Example 1 simulating an indirect tensile test;

[0027] Figure 4 It is the tension chain diagram of the mortar interior and the mortar-aggregate interface of the discrete element specimen model traversed in Example 1. DETAILED DESCRIPTION

[0028] Specific implementation method 1: The evaluation method of the viscoelastic cracking performance of the rubber asphalt mixture in this implementation method is implemented according to the following steps:

[0029] Step 1: cutting the surface of the rubber asphalt mixture Marshall specimen, observing the exposed aggregate in the section of the cut specimen as natural speckle, and obtaining a pre-treated specimen;

[0030] Step 2: Perform image recognition on the cut section of the pre-treated specimen to obtain the aggregate area and the mortar area, respectively, to obtain the pre-treated specimen;

[0031] Step 3: Place the pretreated specimen in a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state. Use a universal testing machine to perform an indirect tensile test on the pretreated specimen to obtain a mechanical loading curve. The maximum load is obtained through the mechanical loading curve, and 80% of the maximum load is used as the control load during the digital speckle test.

[0032] Step 4: Put another pre-treated specimen into a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state, and perform an indirect tensile test on the pre-treated specimen using a universal testing machine. When the load reaches the control load, the loading is stopped, and the image of the asphalt mixture specimen during the indirect tensile test is obtained by a digital speckle image acquisition system.

[0033] Step 5, determine the analysis sub-area, and obtain the surface horizontal strain field of the pretreated specimen in step 4 during the indirect tensile test;

[0034] Step 6: Determine the high strain area S from the surface horizontal strain field in step 5 高应变 ;

[0035] Step 7. The calculation formula of viscoelastic protection index D is as follows:

[0036]

[0037] In the formula, S 砂浆 and S 高应变 are the mortar area and high strain area area respectively;

[0038] Step 8: Construct discrete element specimen model:

[0039] Through CT scanning of a single aggregate, templates of aggregates with different shapes are established, and an aggregate shape template library is constructed. Then, a random generation algorithm is used to generate an asphalt mixture specimen model of the corresponding gradation according to the gradation, and the positions of the constituent particles are obtained as the aggregate positions. Aggregate templates in the aggregate shape template library are randomly retrieved to replace the randomly generated particles. The corresponding contact models and mechanical contact parameters of the components' internal and interface are adjusted to ensure that the discrete element model is in a viscoelastic state, and then a discrete element specimen model is constructed.

[0040] Step 9. Build rectangular walls at the top and bottom of the side of the discrete element specimen model. The rectangular walls are all composed of "facets". The top is the loading wall and the bottom is the bearing wall. The speed of the loading wall is controlled to simulate the indirect tensile test. Stop loading when the load reaches the control load determined in step 3.

[0041] Step 10: traverse the force chain information inside the discrete element specimen model when the control load is reached to obtain the tension chain ratio P inside the mortar and at the mortar-aggregate interface;

[0042] Step 11: Calculate the score M, M = 1-P;

[0043] Step 12: The evaluation result of the viscoelastic cracking performance of the asphalt mixture is S, which is calculated according to the following formula (1), thereby completing the evaluation of the viscoelastic cracking performance of the asphalt mixture;

[0044] S = 0.5*D*100+0.5*M*100(1).

[0045] In step one of the present embodiment, the exposed aggregate is observed as natural speckle to prevent artificial speckle from covering up the information of each component, which has an important influence on the viscoelastic properties of the asphalt mixture. In step three, multiple pre-treated specimens can be used, the temperature is set to 30°C, and 80% of the average maximum load is used as the control load, which ensures the uniformity of the viscoelastic properties and variables of the asphalt mixture under load.

[0046] In step eight of this embodiment, the contact model and mechanical contact parameters corresponding to the internal and interface of the components are adjusted to ensure that the discrete element model conforms to the viscoelastic state of the test specimen, and then the discrete element specimen model is constructed. In step nine, the constructed discrete element specimen model is subjected to a simulated indirect tensile test, and the force-displacement curve obtained from the indirect tensile test of the pretreated specimen in step three is compared. The load peak difference and the maximum load difference (the maximum load difference is the maximum value of the load difference of the force-displacement curve) are obtained from the force-displacement curve. The load peak difference and the maximum load difference are used as evaluation indicators. When the load peak difference is within 10% and the maximum load difference is within 15%, the discrete element simulation results are accepted. If they do not meet the requirements, the mechanical contact parameters in step eight are readjusted.

[0047] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that in step 3, the pre-treated specimen is placed in a constant temperature box and kept warm at 30° C. for more than 6 hours to ensure that the asphalt mixture is in a viscoelastic state.

[0048] Specific implementation method three: This implementation method is different from specific implementation method two in that an air bath heat preservation method is adopted in the constant temperature box.

[0049] Specific implementation method 4: The difference between this implementation method and any one of specific implementation methods 1 to 3 is that in step 3, a universal testing machine is used to perform an indirect tensile test on the pretreated specimen, the loading rate is set to 50 mm / min, the loading bar width is 12.7 mm, and loading is stopped when the load reaches the control load.

[0050] Specific implementation method five: This implementation method is different from any one of specific implementation methods one to four in that in step four, the image of the asphalt mixture specimen during the indirect tensile test loading process is acquired by a digital speckle image acquisition system, and the image acquisition frequency is set to 5 images per second.

[0051] Specific implementation method 6: The difference between this implementation method and any one of specific implementation methods 1 to 5 is that in step 5, the size of the analysis sub-area is determined to be 15 to 20 pixels (pixel units) and the step length is 5 pixels.

[0052] Specific implementation method 7: This implementation method is different from any one of specific implementation methods 1 to 6 in that in step 6, a strain point with a high strain index greater than 4 is determined as a high strain area.

[0053] Specific embodiment eight: This embodiment is different from specific embodiment seven in that the calculation method of the high strain index H is as follows:

[0054]

[0055] In the formula, ε i , ε 平均 are the tensile strain at the strain point and the overall average tensile strain of the pretreated specimen, respectively.

[0056] Specific implementation method 9: The difference between this implementation method and any one of specific implementation methods 1 to 8 is that in step 8, PFC3d software is used to construct a discrete element specimen model.

[0057] Specific implementation method ten: The difference between this implementation method and any one of specific implementation methods one to nine is that the larger the S value in step twelve, the better the anti-viscoelastic cracking effect.

[0058] Embodiment 1: The evaluation method of the viscoelastic cracking performance of the rubber asphalt mixture in this embodiment is implemented according to the following steps:

[0059] 1. Cut the upper and lower surfaces of the SMA-13 ​​standard rubber asphalt mixture specimen. After cutting, determine that the height of the standard asphalt mixture specimen is 50 mm and the diameter is 101.6 mm. Ensure that the cut surface is smooth and flat, and use the exposed aggregate on the cut surface as natural speckle;

[0060] 2. Perform image recognition on the surface of the cut specimen to obtain the aggregate area and mortar area. The mortar area ratio is 12.1%, and the pre-treated specimen is obtained; Figure 1 This is the image recognition diagram of the Marshall specimen of asphalt mixture;

[0061] 3. Place the pretreated specimen in a temperature control box for more than 6 hours, use an air bath to keep warm, the temperature is 30°C, use UTM-250 loading equipment to carry out indirect tensile test on the pretreated specimen, the loading speed is 50mm / min, and the curve of loading force changing with time is recorded during the test. Load 3 parallel specimens, the average maximum load is 8.3kN, so the control load is 6.6kN;

[0062] Fourth, synchronously control the UTM-250 loading device and the digital speckle image acquisition system, and conduct an indirect tensile test on another pre-treated specimen (asphalt mixture Marshall specimen) with surface cutting. Stop loading when the load reaches the control load, and obtain the image of the asphalt mixture during the indirect tensile test through the digital speckle image acquisition system. Considering the hardware equipment and accuracy requirements, the image acquisition frequency is set to 5 images per second;

[0063] 5. Since viscoelastic cracking is affected by large deformation cracking, the mechanical evaluation based on brittle cracking is difficult to accurately reflect the results. Therefore, strain is used as the main evaluation criterion. The size of the analysis sub-area is determined to be 20 pixels and the step size is 5 pixels based on comprehensive efficiency and accuracy. Strain information is calculated, and the surface horizontal strain field of the pre-treated specimen (asphalt mixture Marshall specimen) during the indirect tensile test is obtained from the image obtained in step 4. Figure 2 is the surface horizontal strain field of the asphalt mixture Marshall specimen during the indirect tensile test;

[0064] 6. Horizontal tensile strain is related to cracking. Only horizontal tensile strain is counted. The high strain is determined according to the high strain index to determine the proportion of the high strain area. The strain point with a high strain index greater than 4 is the high strain area. The calculation method of the high strain index is shown in the following formula. In this embodiment, the area proportion of the high strain area is determined to be 3.54%;

[0065]

[0066] In the formula, ε i , ε 平均 are the tensile strain at the strain point and the overall average tensile strain of the pretreated specimen, respectively;

[0067] 7. Compare the high strain area with the mortar area ratio, and propose a viscoelastic protection index D. The viscoelastic protection index is shown in the following formula. The larger the D, the better. In this embodiment, D is calculated to be 70.7%;

[0068]

[0069] In the formula, S 砂浆 , S 高应变 are the area ratios of mortar and high strain area, respectively;

[0070] 8. Construct discrete element specimen model. The discrete element geometric specimen model adopts a combination of image processing (aggregate morphology) + random generation (aggregate position). Simple in-situ image processing is too time-consuming, and the accuracy of the random model is relatively low. Therefore, a combination of the two is adopted. The aggregate model is obtained by image processing to generate an aggregate morphology template library. The aggregate model parameters are distance (distance, representing the smoothness of the model surface) = 150, ratio (ratio, representing the ratio of the minimum particle size to the maximum particle size of the internal component particles of the coarse aggregate model) = 0.3. According to the SMA13 grading, a random generation algorithm is used to generate the corresponding specimen model, and the component particle position is obtained as the aggregate position. The aggregate template library morphology is randomly retrieved to replace the randomly generated particles, thereby achieving the construction of the specimen model. The contact parameters of each component are adjusted with the help of indoor test results. The contact between aggregates is set to a linear stiffness contact model (no contact is required inside the aggregate Clump block), and the contact inside the mortar and between the mortar and the aggregate is set to a linear contact bonding model.

[0071] Table 1 Contact parameters between aggregates

[0072]

[0073] Table 2 Contact parameters inside asphalt mortar

[0074]

[0075] Table 3 Contact parameters between asphalt mortar and aggregate

[0076]

[0077] 9. Construct rectangular walls at the top and bottom of the side of the discrete element specimen model. The rectangular walls are composed of "facets". The top is the loading wall and the bottom is the bearing wall. The speed of the loading wall is controlled to simulate the indirect tensile test. Stop loading when the load reaches the control load determined in step 3; Figure 3 This is the discrete element simulation diagram of indirect tension of standard Marshall specimen;

[0078] 10. Traverse the force chain information inside the discrete element specimen model when the control load is reached, obtain the force chain information of each component, and obtain the tension chain ratio P inside the mortar and at the mortar-aggregate interface; Figure 4 The tensile force chain diagram of the mortar interior and the mortar-aggregate interface of the asphalt mixture Marshall specimen obtained in this embodiment;

[0079] 11. The smaller the proportion of mortar tension chain, the better. The proportion of tension chain P inside the mortar and at the mortar-aggregate interface is 57.2%, so the score M is 42.8%;

[0080] 12. The evaluation result of the viscoelastic cracking performance of asphalt mixture is S. The larger S is, the better the anti-viscoelastic cracking effect is. S is calculated according to the following formula (1), thereby completing the evaluation of the viscoelastic cracking performance of asphalt mixture;

[0081] S=0.5*D*100+0.5*M*100 (1).

[0082] The viscoelastic cracking performance evaluation result of SMA13 measured in this embodiment is S=56.75, and the anti-viscoelastic cracking performance is relatively excellent, indicating that the SMA13 skeleton plays a certain role in bearing, and the specific gravity of the mortar tension chain is relatively reasonable, which is also reflected in the small high strain area of ​​the mortar.

Claims

1. The evaluation method of viscoelastic cracking performance of rubber asphalt mixture is characterized by The evaluation method of the viscoelastic cracking performance of the rubber asphalt mixture is implemented according to the following steps: Step 1: cutting the surface of the rubber asphalt mixture Marshall specimen, observing the exposed aggregate in the section of the cut specimen as natural speckle, and obtaining a pre-treated specimen; Step 2: Perform image recognition on the cut section of the pre-treated specimen to obtain the aggregate area and mortar area respectively; Step 3: Place the pretreated specimen in a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state. Use a universal testing machine to perform an indirect tensile test on the pretreated specimen to obtain a mechanical loading curve. The maximum load is obtained through the mechanical loading curve, and 80% of the maximum load is used as the control load during the digital speckle test. Step 4: Put another pre-treated specimen into a constant temperature box to ensure that the asphalt mixture is in a viscoelastic state, and perform an indirect tensile test on the pre-treated specimen using a universal testing machine. When the load reaches the control load, the loading is stopped, and the image of the asphalt mixture specimen during the indirect tensile test is obtained by a digital speckle image acquisition system. Step 5, determine the analysis sub-area, and obtain the surface horizontal strain field of the pretreated specimen in step 4 during the indirect tensile test; Step 6: Determine the high strain area S from the surface horizontal strain field in step 5 高应变 ; Step 7. The calculation formula of viscoelastic protection index D is as follows: In the formula, S 砂浆 and S 高应变 are the mortar area and high strain area area respectively; Step 8: Construct discrete element specimen model: Through CT scanning of a single aggregate, templates of aggregates with different shapes are established, and an aggregate shape template library is constructed. Then, a random generation algorithm is used to generate an asphalt mixture specimen model of the corresponding gradation according to the gradation, and the positions of the constituent particles are obtained as the aggregate positions. Aggregate templates in the aggregate shape template library are randomly retrieved to replace the randomly generated particles. The corresponding contact models and mechanical contact parameters of the components' internal and interface are adjusted to ensure that the discrete element model is in a viscoelastic state, and then a discrete element specimen model is constructed. Step 9. Construct rectangular walls at the top and bottom of the side of the discrete element specimen model. The rectangular walls are all composed of "facets". The top is the loading wall and the bottom is the bearing wall. The speed of the loading wall is controlled to simulate the indirect tensile test. Stop loading when the load reaches the control load determined in step 3. Step 10: traverse the force chain information inside the discrete element specimen model when the control load is reached to obtain the tension chain ratio P inside the mortar and at the mortar-aggregate interface; Step 11: Calculate the score M, M = 1-P; Step 12: The evaluation result of the viscoelastic cracking performance of the asphalt mixture is S, which is calculated according to the following formula (1), thereby completing the evaluation of the viscoelastic cracking performance of the asphalt mixture; S = 0.5*D*100+0.5*M*100(1).

2. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that In step three, the pretreated specimens are placed in a constant temperature box and kept at 30°C for more than 6 hours to ensure that the asphalt mixture is in a viscoelastic state.

3. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 2, characterized in that An air bath insulation method is used in a constant temperature box.

4. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that In step three, a universal testing machine was used to perform an indirect tensile test on the pretreated specimen. The loading rate was set to 50 mm / min, the loading bar width was 12.7 mm, and the loading was stopped when the control load was reached.

5. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that In step 4, the digital speckle image acquisition system is used to obtain images of the asphalt mixture specimen during the loading process of the indirect tensile test, and the image acquisition frequency is set to 5 images per second.

6. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that In step 5, the size of the analysis sub-area is determined to be 15 to 20 pixels, with a step length of 5 pixels.

7. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that In step 6, the strain points with high strain index greater than 4 are determined as high strain areas.

8. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 7, characterized in that The high strain index H is calculated as follows: In the formula, ε i , ε 平均 are the tensile strain at the strain point and the overall average tensile strain of the pretreated specimen, respectively.

9. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that Step 8: Use PFC3d software to construct a discrete element specimen model.

10. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixture according to claim 1, characterized in that The larger the S value in step 12, the better the anti-viscoelastic cracking effect.

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