Method for evaluating viscoelastic cracking performance of rubber asphalt mixture

Abstract

The application discloses a method for evaluating viscoelastic cracking performance of rubber asphalt mixture, and aims at solving the problem that current evaluation of cracking performance of rubber asphalt mixture is limited to brittle cracking at low temperature and does not involve evaluation of viscoelastic cracking performance. The evaluation method comprises the following steps: 1, cutting a Marshall test piece; 2, image recognition; 3, performing an indirect tensile test on the Marshall test piece of the asphalt mixture to determine a control load; 4, collecting photos of the asphalt mixture in a loading process of the indirect tensile test; 5, calculating and obtaining a surface strain field of the Marshall test piece of the asphalt mixture in the indirect tensile test process; 6, calculating a high strain index to determine a high strain area proportion; 7, calculating a viscoelastic protection index; 8, constructing a discrete element test piece model; 9, performing indirect tensile simulation; 10, counting mortar tension chains; 11, calculating a mortar tension chain score; and 12, evaluating. The application combines the image recognition technology and the discrete element modeling, and effectively improves the accuracy of the evaluation result.

Description

Technical Field

[0001] This invention belongs to the field of asphalt mixture evaluation technology, specifically relating to an evaluation method for the viscoelastic cracking performance of rubber asphalt mixtures. Background Technology

[0002] my country currently faces a large problem in disposing of waste tires. Processing waste rubber tires into rubber powder to produce rubber asphalt is an effective method. As a typical viscoelastic and temperature-sensitive material, rubber asphalt pavements exhibit large real-time deformation characteristics under temperature-load coupling.

[0003] Asphalt mixtures are mainly composed of elastic aggregates, viscoelastic-plastic asphalt mortar, and voids. They are significantly affected by temperature, exhibiting an overall viscoelastic-plastic characteristic. However, the viscoelastic properties and overall performance are uncertain due to the influence of asphalt content and temperature. At higher temperatures, asphalt exhibits fluidity, and industry professionals focus more on the rutting resistance of asphalt mixtures; regarding cracking performance, they often emphasize brittle cracking at low temperatures. In fact, under large deformations and external forces, asphalt mixtures in a viscoelastic state will experience bonding and cohesive failure, specifically manifesting as cracking. The viscoelastic cracking phenomenon is more pronounced in rubber-asphalt mixtures. However, research on the viscoelastic cracking of rubber-asphalt mixtures is scarce.

[0004] The Discrete Element Method (DEM) is a numerical method based on discontinuous medium theory to simulate the mechanical behavior of granular materials. It is suitable for analyzing the micromechanical properties and stress-deformation of granular or cementitious materials, quantifying the transmission and distribution of internal force chain fields during loading, and intuitively expressing the forces and displacements of each particle. The Digital Speckle Correlation Method (DIC) can obtain the evolution of the displacement and strain fields on the material surface under load, and can be used to analyze the micromechanical deformation characteristics of asphalt mixtures under loading modes. Therefore, using the Discrete Element Method (DEM) and the Digital Speckle Correlation Method (DIC) as research tools, and using the contact force chain field and micromechanical deformation field as analytical indicators to evaluate the viscoelastic cracking of asphalt mixtures, has practical application value. Summary of the Invention

[0005] The purpose of this invention is to address the problem that rubber asphalt mixtures crack under external loads when in a viscoelastic state, and that current evaluations of the cracking performance of rubber asphalt mixtures are limited to brittle cracking at low temperatures and do not address the evaluation of viscoelastic cracking performance. Therefore, this invention provides a method for evaluating the viscoelastic cracking performance of rubber asphalt mixtures.

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

[0007] Step 1: Cut the surface of the Marshall specimen of rubber asphalt mixture. The exposed aggregate in the cross-section of the cut specimen is used as natural speckle for observation to obtain the pretreated specimen.

[0008] Step 2: Perform image recognition on the cross-section of the pretreated specimen after cutting to obtain the aggregate area and mortar area respectively, and obtain the pretreated specimen;

[0009] Step 3: Place the pretreated specimens in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Use a universal testing machine to conduct indirect tensile tests on the pretreated specimens to obtain the mechanical loading curve. Use 80% of the maximum load as the control load for digital speckle testing.

[0010] Step 4: Place another pretreated specimen in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Perform an indirect tensile test on the pretreated specimen using a universal testing machine. Stop loading when the control load is reached. Use a digital speckle image acquisition system to acquire images of the asphalt mixture specimen during the indirect tensile test loading process.

[0011] Step 5: Determine the analysis sub-region and obtain the surface horizontal strain field of the pretreated specimen from Step 4 during the indirect tensile test.

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

[0013] Step 7: The formula for calculating the viscoelastic protection index D is as follows:

[0014]

[0015] In the formula, S 砂浆 and S 高应变 These represent the mortar area and the high-strain zone area, respectively.

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

[0017] By scanning individual aggregates with CT, different aggregate templates are established to construct an aggregate morphology template library. Then, according to the gradation, a random generation algorithm is used to generate asphalt mixture specimen models with corresponding gradations. The positions of the constituent particles are obtained as the aggregate positions. The aggregate templates in the aggregate morphology template library are randomly selected to replace the randomly generated particles. The contact models and mechanical contact parameters of the components inside and at the interface are adjusted to ensure that the discrete element model is in a viscoelastic state, thereby constructing a discrete element specimen model.

[0018] Step 9: Construct rectangular walls on the top and bottom sides 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 loading wall is speed controlled to simulate the indirect tensile test. The loading is stopped when the control load determined in step 3 is reached.

[0019] Step 10: Traverse the force chain information inside the discrete element specimen model when the control load is reached, and obtain the proportion P of the tensile chain 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 asphalt mixture is S. S is calculated according to the following formula (1), thus completing the evaluation of the viscoelastic cracking performance of asphalt mixture.

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

[0023] This invention proposes a method for evaluating the viscoelastic cracking performance of rubber-asphalt mixtures using image recognition technology and discrete element modeling (DEM), providing a research approach to address and emphasize the viscoelastic cracking phenomenon in asphalt mixtures. While the viscoelastic cracking phenomenon in rubber-asphalt mixtures is evident, current research only focuses on low-temperature brittle cracking and high-temperature rutting, leading to an inability to evaluate viscoelastic cracking and neglecting the cracking phenomenon occurring in pavements under viscoelastic conditions. This invention employs digital speckle mapping and DEM, combining actual testing with simulation, effectively solving the problem of obtaining difficult-to-obtain actual test data and improving the accuracy of simulation. DEM proposes a method for creating geometric specimen models using a combination of image processing (aggregate morphology) and random generation (aggregate location), balancing efficiency and accuracy. Furthermore, it proposes a viscoelastic protection index and a tensile chain ratio index within the mortar and at the mortar-aggregate interface, fully considering the significant influence of asphalt mortar on the viscoelastic properties of asphalt mixtures. By combining actual deformation with mechanical analysis, this method aligns with 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 consistent with the current use of asphalt pavements and helps to evaluate the performance and design guidance of asphalt mixtures. Attached Figure Description

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

[0025] Figure 2 This refers to the surface horizontal strain field during the controlled load process in the indirect tensile test in Example 1.

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

[0027] Figure 4 This is a tensile chain diagram of the mortar interior and mortar-aggregate interface of the discrete element specimen model obtained by traversal in Example 1. Detailed Implementation

[0028] Specific Implementation Method 1: The evaluation method for the viscoelastic cracking performance of rubber asphalt mixtures in this implementation method is carried out according to the following steps:

[0029] Step 1: Cut the surface of the Marshall specimen of rubber asphalt mixture. The exposed aggregate in the cross-section of the cut specimen is used as natural speckle for observation to obtain the pretreated specimen.

[0030] Step 2: Perform image recognition on the cross-section of the pretreated specimen after cutting to obtain the aggregate area and mortar area respectively, and obtain the pretreated specimen;

[0031] Step 3: Place the pretreated specimens in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Use a universal testing machine to conduct indirect tensile tests on the pretreated specimens to obtain the mechanical loading curve. Obtain the maximum load through the mechanical loading curve and use 80% of the maximum load as the control load for digital speckle testing.

[0032] Step 4: Place another pretreated specimen in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Perform an indirect tensile test on the pretreated specimen using a universal testing machine. Stop loading when the control load is reached. Use a digital speckle image acquisition system to acquire images of the asphalt mixture specimen during the indirect tensile test loading process.

[0033] Step 5: Determine the analysis sub-region and obtain the surface horizontal strain field of the pretreated specimen from Step 4 during the indirect tensile test.

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

[0035] Step 7: The formula for calculating the viscoelastic protection index D is as follows:

[0036]

[0037] In the formula, S 砂浆 and S 高应变 These represent the mortar area and the high-strain zone area, respectively.

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

[0039] By scanning individual aggregates with CT, different aggregate templates are established to construct an aggregate morphology template library. Then, according to the gradation, a random generation algorithm is used to generate asphalt mixture specimen models with corresponding gradations. The positions of the constituent particles are obtained as the aggregate positions. The aggregate templates in the aggregate morphology template library are randomly selected to replace the randomly generated particles. The contact models and mechanical contact parameters of the components inside and at the interface are adjusted to ensure that the discrete element model is in a viscoelastic state, thereby constructing a discrete element specimen model.

[0040] Step 9: Construct rectangular walls on the top and bottom sides 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 loading wall is speed controlled to simulate the indirect tensile test. The loading is stopped when the control load determined in step 3 is reached.

[0041] Step 10: Traverse the force chain information inside the discrete element specimen model when the control load is reached, and obtain the proportion P of the tensile chain 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 asphalt mixture is S. S is calculated according to the following formula (1), thus completing the evaluation of the viscoelastic cracking performance of asphalt mixture.

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

[0045] In step one of this implementation method, the exposed aggregate is observed as a natural speckle to prevent artificial speckle from obscuring the information of each component, which has an important impact on the viscoelastic properties of the asphalt mixture. In step three, multiple pretreated specimens can be used, with the temperature set at 30°C and the average maximum load of 80% as the control load, to ensure the uniformity of the viscoelastic characteristics and variables of the asphalt mixture under load.

[0046] In step eight of this implementation method, the contact models and mechanical contact parameters of the internal components and interfaces are adjusted to ensure that the discrete element model conforms to the viscoelastic state of the test specimen, thereby constructing a discrete element specimen model. 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 pre-processed specimen in step three is compared. The load peak difference and the load maximum difference (the load maximum difference is the maximum value of the load difference in the force-displacement curve) are obtained from the force-displacement curve. The load peak difference and the load maximum difference are used as evaluation indicators. When the load peak difference is within 10% and the load maximum difference is within 15%, the discrete element simulation result is accepted. If it does not meet the requirements, the mechanical contact parameters in step eight are readjusted.

[0047] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that in step three, the pretreated specimens are placed in a constant temperature chamber and kept at 30°C for more than 6 hours to ensure that the asphalt mixture is in a viscoelastic state.

[0048] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that it adopts an air bath insulation method in the constant temperature chamber.

[0049] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that in step three, a universal testing machine is used to conduct an indirect tensile test on the pretreated specimen. The loading rate is set to 50 mm / min, the width of the loading strip is 12.7 mm, and loading is stopped when the control load is reached.

[0050] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that, in step 4, images of the asphalt mixture specimens during the indirect tensile test are acquired using a digital speckle image acquisition system, with the image acquisition frequency set to 5 frames per second.

[0051] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the size of the analysis sub-region is determined to be 15-20 pixels in step five, with a step size of 5 pixels.

[0052] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that in step six, the strain point with a high strain index greater than 4 is determined as the high strain region.

[0053] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the high strain index H is calculated using the following method:

[0054]

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

[0056] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that step eight uses PFC3d software to construct a discrete element specimen model.

[0057] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the larger the S value in step 12, the better the anti-viscoelastic cracking effect.

[0058] Example 1: The evaluation method for the viscoelastic cracking performance of rubber asphalt mixtures in this example 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 the height of the standard asphalt mixture specimen to be 50 mm and the diameter to be 101.6 mm. Ensure that the cut surface is smooth and flat, and treat the exposed aggregate on the cut surface as natural speckle.

[0060] 2. Image recognition was performed on the surface of the cut specimen to obtain the aggregate area and mortar area. The mortar area ratio was 12.1%, resulting in a pretreated specimen. Figure 1 Image recognition diagram of Marshall specimens of asphalt mixture;

[0061] 3. Place the pretreated specimens in a temperature-controlled chamber and keep them at a temperature of 30℃ using an air bath. Use a UTM-250 loading device to perform indirect tensile tests on the pretreated specimens at a loading speed of 50 mm / min. Record the curve of the loading force versus time during the test. Load 3 parallel specimens. The average maximum load is 8.3 kN, thus the control load is 6.6 kN.

[0062] IV. Synchronously control the UTM-250 loading device and the digital speckle image acquisition system to conduct an indirect tensile test on another pre-treated specimen (asphalt mixture specimen) with surface cutting. Loading is stopped when the control load is reached. The digital speckle image acquisition system is used to acquire images of the asphalt mixture during the indirect tensile test. Considering the hardware equipment and accuracy requirements, the image acquisition frequency is set to 5 frames per second.

[0063] V. Due to the influence of large deformation cracking on viscoelastic cracking, mechanical evaluation based on brittle cracking is difficult to accurately reflect the results. Therefore, strain is used as the main evaluation standard. Considering both efficiency and accuracy, the analysis sub-region size is determined to be 20 pixels, with a step size of 5 pixels. Strain information is calculated, and the surface horizontal strain field of the pretreated specimen (asphalt mixture Marshall specimen) during the indirect tensile test is obtained from the image acquired in step four. Figure 2 The surface horizontal strain field of the obtained asphalt mixture Marshall specimen during the indirect tensile test;

[0064] VI. Horizontal tensile strain is related to cracking. Only horizontal tensile strain is statistically analyzed. The proportion of high strain zone is determined based on the high strain index. The strain point with a high strain index greater than 4 is the high strain zone. The calculation method of the high strain index is shown in the following formula. In this embodiment, the area proportion of high strain zone is determined to be 3.54%.

[0065]

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

[0067] 7. By comparing the ratio of high strain zone to mortar area, the viscoelastic protection index D is proposed. The viscoelastic protection index is shown in the following formula. The larger D is, the better. In this embodiment, D is calculated to be 70.7%.

[0068]

[0069] In the formula, S 砂浆 S 高应变 These represent the area ratios of mortar and the high-strain zone, respectively.

[0070] 8. Constructing Discrete Element Specimen Models: The discrete element geometric specimen model adopts a combination of image processing (aggregate morphology) and random generation (aggregate position). Simple in-situ image processing is too time-consuming, while the accuracy of random models is relatively reduced. Therefore, a combination of the two is adopted. Image processing is used to obtain aggregate models to generate an aggregate morphology template library. The aggregate model parameters are distance (representing the smoothness of the model surface) = 150 and ratio (representing the ratio of the minimum to the maximum particle size of the constituent particles inside the coarse aggregate model) = 0.3. According to the SMA13 gradation, a random generation algorithm is used to generate the corresponding specimen model. The positions of the constituent particles are obtained as the aggregate positions. The aggregate template library morphology is randomly selected to replace the randomly generated particles, thereby achieving the construction of the specimen model. The contact parameters of each component are adjusted based on the results of indoor tests. The contact between aggregates is set to a linear stiffness contact model (no contact needs to be set 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 discrete element specimen model. These walls are all composed of "facets," with the top serving as the loading wall and the bottom as the bearing wall. Speed ​​control is applied to the loading walls to simulate an indirect tensile test. Loading is stopped when the control load determined in step 3 is reached. Figure 3 The following is a discrete element simulation diagram of indirect tensile stress on a 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 tensile chain ratio P inside the mortar and at the mortar-aggregate interface. Figure 4 This is a tensile chain diagram of the mortar interior and mortar-aggregate interface of the Marshall specimen of asphalt mixture obtained in this embodiment;

[0079] 11. The smaller the proportion of mortar tension chains, the better. The proportion of tension chains inside the mortar and at the mortar-aggregate interface, P, is 57.2%, therefore 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. S is calculated according to the following formula (1), thus completing the evaluation of the viscoelastic cracking performance of asphalt mixture.

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

[0082] The SMA13 viscoelastic cracking performance evaluation result measured in this embodiment is S=56.75, which shows excellent viscoelastic cracking resistance. This indicates that the SMA13 skeleton plays a certain role in load bearing, the mortar tension chain has a relatively reasonable specific gravity, and is also reflected in the small high strain zone of the mortar.

Claims

1. A method for evaluating the viscoelastic cracking properties of rubber-asphalt mixtures, characterized in that... The evaluation method for the viscoelastic cracking performance of this rubber-asphalt mixture is implemented according to the following steps: Step 1: Cut the surface of the Marshall specimen of rubber asphalt mixture. The exposed aggregate in the cross-section of the cut specimen is used as natural speckle for observation to obtain the pretreated specimen. Step 2: Perform image recognition on the cross-section of the pre-treated specimen after cutting to obtain the aggregate area and mortar area respectively; Step 3: Place the pretreated specimens in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Use a universal testing machine to conduct indirect tensile tests on the pretreated specimens to obtain the mechanical loading curve. Obtain the maximum load through the mechanical loading curve and use 80% of the maximum load as the control load for digital speckle testing. Step 4: Place another pretreated specimen in a constant temperature chamber to ensure that the asphalt mixture is in a viscoelastic state. Perform an indirect tensile test on the pretreated specimen using a universal testing machine. Stop loading when the control load is reached. Use a digital speckle image acquisition system to acquire images of the asphalt mixture specimen during the indirect tensile test loading process. Step 5: Determine the analysis sub-region and obtain the surface horizontal strain field of the pretreated specimen from Step 4 during the indirect tensile test. Step 6: Determine the area S of the high-strain region from the surface horizontal strain field in Step 5. 高应变 ; Step 7: The formula for calculating the viscoelastic protection index D is as follows: In the formula, S 砂浆 and S 高应变 These represent the mortar area and the high-strain zone area, respectively. Step 8: Construct a discrete element specimen model: By scanning individual aggregates with CT, different aggregate templates are established to construct an aggregate morphology template library. Then, according to the gradation, a random generation algorithm is used to generate asphalt mixture specimen models with corresponding gradations. The positions of the constituent particles are obtained as the aggregate positions. The aggregate templates in the aggregate morphology template library are randomly selected to replace the randomly generated particles. The contact models and mechanical contact parameters of the components inside and at the interface are adjusted to ensure that the discrete element model is in a viscoelastic state, thereby constructing a discrete element specimen model. Step 9: Construct rectangular walls on the top and bottom sides 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 loading wall is speed controlled to simulate the indirect tensile test. The loading is stopped when the control load determined in step 3 is reached. Step 10: Traverse the force chain information inside the discrete element specimen model when the control load is reached, and obtain the proportion P of the tensile chain 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 asphalt mixture is S. S is calculated according to the following formula (1), thus completing the evaluation of the viscoelastic cracking performance of asphalt mixture. S = 0.5 * D * 100 + 0.5 * M * 100 (1).

2. The method for evaluating the viscoelastic cracking performance of rubber-asphalt mixtures according to claim 1, characterized in that... In step three, the pretreated specimens are placed in a constant temperature chamber 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 mixtures according to claim 2, characterized in that... An air bath insulation method is used in the constant temperature chamber.

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

5. The method for evaluating the viscoelastic cracking performance of rubber-asphalt mixtures according to claim 1, characterized in that... In step four, images of the asphalt mixture specimens during the indirect tensile test are acquired using a digital speckle image acquisition system, with the image acquisition frequency set to 5 frames per second.

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

7. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixtures according to claim 1, characterized in that... In step six, strain points with a high strain index greater than 4 are identified as high strain zones.

8. The method for evaluating the viscoelastic cracking performance of rubber asphalt mixtures according to claim 7, characterized in that... The high strain index H is calculated as follows: In the formula, ε i ε 平均 These represent 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 mixtures 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 mixtures according to claim 1, characterized in that... In step twelve, the larger the S value, the better the anti-viscoelastic cracking effect.

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