Improved asphalt high-temperature performance grading method

Abstract

The invention belongs to the technical field of road engineering, and particularly relates to an improved asphalt high-temperature performance grading method which comprises the following steps: preparing an asphalt test piece; carrying out an MSCR test on the original sample asphalt test piece; dividing the high-temperature grade and the applicable traffic grade of the original asphalt; performing an MSCR test on the aged asphalt test piece; dividing the high-temperature grade and the applicable traffic grade of the aged asphalt; and determining the high-temperature grade of the asphalt and the applicable traffic grade according to the high-temperature grade and traffic grade division results of the original asphalt and the aged asphalt. Aiming at the defects of the existing asphalt high-temperature performance grading method, the high-temperature performance of the original asphalt and the aged asphalt is evaluated by adopting the same test method and consistent indexes, so that the high-temperature performance of the asphalt can be more accurately evaluated, and the high-temperature grade of the asphalt can be more accurately divided. In the absence of aging equipment, the invention also provides an idea for preliminarily determining the high-temperature grade and the applicable traffic grade of the asphalt according to the high-temperature performance of the original asphalt.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, and in particular relates to an improved method for classifying the high-temperature performance of asphalt. Background Technology

[0002] Asphalt pavement is the main paving form for roads of all grades in my country. Asphalt, as one of the raw materials for asphalt pavement, has always been a key research focus in the field of road engineering, as the selection of asphalt scientifically and rationally based on local environment and traffic conditions is crucial. Asphalt grading systems serve as the basis for optimal selection. Currently, commonly used asphalt grading systems worldwide include penetration grading systems, viscosity grading systems, and performance grading systems. Among these, the performance grading system, based on the rheological properties of asphalt, can more accurately evaluate the road performance of asphalt compared to the penetration and viscosity grading systems, and therefore has been promoted and applied in many countries.

[0003] In the initial performance grading system, the rutting factor | G *| / sin δ As an evaluation index for assessing the high-temperature performance of undisturbed asphalt and aged asphalt, | G *| represents the dynamic shear modulus. δ It refers to the phase angle. A higher rutting factor in asphalt indicates stronger high-temperature rutting resistance. The performance grading system requires a rutting factor of not less than 1.0 kPa for undisturbed asphalt and not less than 2.2 kPa for aged asphalt, and determines the high-temperature grade of the asphalt based on this. Although the rutting factor can accurately evaluate the high-temperature performance of base asphalt, it still has many limitations. For example, the sinusoidal load applied in the dynamic shear test cannot effectively simulate the rutting mechanism of asphalt pavement; in the derivation of the rutting factor, only a simple mathematical model of shear stress and shear strain is assumed, without considering the influence of viscosity on shear strain; the number of loading cycles in the dynamic shear test is insufficient to allow the properties of some modified asphalts to reach a steady state, etc. Therefore, the rutting factor often underestimates the high-temperature performance of modified asphalt, especially polymer-modified asphalt.

[0004] Given the limitations of rutting factors, the Multiple Stress Creep Recovery (MSCR) test has been widely used in recent years to evaluate the high-temperature performance of asphalt. The MSCR test employs a creep recovery loading mode, which can isolate the irrecoverable strain of asphalt and calculate the irrecoverable creep compliance based on this strain, thus providing a more accurate evaluation of the high-temperature performance of asphalt. The latest performance grading system uses the MSCR test to evaluate the high-temperature performance of asphalt after short-term aging treatment, using the irrecoverable creep compliance at 3.2 kPa as the benchmark. J nr3.2This method aims to determine the high-temperature rating and applicable traffic class of aged asphalt. However, for undisturbed asphalt, the latest performance grading system still uses the rutting factor to evaluate its high-temperature performance; therefore, this method still has significant limitations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an improved method for classifying the high-temperature performance of asphalt, thereby more accurately classifying the high-temperature performance and applicable traffic levels of asphalt.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an improved method for classifying the high-temperature performance of asphalt, the method comprising the following steps: S1. After subjecting the asphalt to be evaluated to short-term aging treatment, prepare original asphalt specimens and aged asphalt specimens respectively. S2. Select the initial test temperature according to the type of asphalt, and conduct MSCR tests on the undisturbed asphalt specimens at this temperature. Obtain the data on the change of shear strain over time in the MSCR test to calculate the average unrecoverable creep compliance of the undisturbed asphalt specimens at a creep stress level of 3.2 kPa. J nr3.2 ; S3. Judging the original asphalt specimen J nr3.2 Is the calculated value less than or equal to 10 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was repeated to determine the high-temperature rating and applicable traffic class of the original asphalt sample; S4. Based on the high temperature rating of the original asphalt sample, select the initial test temperature. At this temperature, conduct MSCR tests on the aged asphalt specimens and obtain the data on the change of shear strain over time during the MSCR tests to calculate the average unrecoverable creep compliance of the aged asphalt specimens at a creep stress level of 3.2 kPa. J nr3.2 ; S5. Judging the aging of asphalt specimens J nr3.2 Is the calculated value less than or equal to 4.5 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was repeated to determine the high-temperature rating and applicable traffic class of the aged asphalt. S6. Based on the high temperature rating and traffic rating of the original asphalt and aged asphalt, determine the high temperature rating and applicable traffic rating of the asphalt to be evaluated.

[0007] Preferably, the average non-recoverable creep compliance at a creep stress level of 3.2 kPa J nr3.2 The calculation formula is as follows: (1) (2) In the formula: N Number of creep recovery cycles; J nr (3.2, N The asphalt specimen under a creep stress level of 3.2 kPa was at the [missing information - likely a specific stress level]. N The irreversible creep compliance at the end of the creep recovery cycle; ε 0 represents the shear strain of the asphalt specimen at the beginning of the creep stage in a single creep recovery cycle; ε r The shear strain of the asphalt specimen at the end of the recovery phase in a single creep recovery cycle.

[0008] Preferably, in step S3, the method for determining the high-temperature grade and applicable traffic grade of the original asphalt sample is as follows: If in step S2 J nr3.2 Calculated value greater than 10 kPa −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until... J nr3.2 Calculated value less than or equal to 10 kPa −1 ; If in step S2 J nr3.2 The calculated value is greater than 4.4 kPa. −1 And less than or equal to 10 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 2.2 kPa. −1 And less than or equal to 4.4 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 1.1 kPa. −1 And less than or equal to 2.2 kPa −1If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is less than or equal to 1.1 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C.

[0009] Preferably, in step S5, the method for determining the high-temperature rating and applicable traffic level of the aged asphalt is as follows: If in step S4 J nr3.2 The calculated value is greater than 4.5 kPa. −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until... J nr3.2 The calculated value is less than or equal to 4.5 kPa. −1 ; If in step S4 J nr3.2 Calculated value greater than 2 kPa −1 And less than or equal to 4.5 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 Calculated value greater than 1 kPa −1 And less than or equal to 2 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is greater than 0.5 kPa. −1 And less than or equal to 1 kPa−1 If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is less than or equal to 0.5 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C.

[0010] Preferably, in steps S3 and S5, traffic level S represents the standard level, indicating that the applicable traffic conditions are a traffic volume of less than 10 million equivalent axles and a vehicle speed of greater than 70 km / h; traffic level H represents the heavy-load level, indicating that the applicable traffic conditions are a traffic volume of 10 million to 30 million equivalent axles or a vehicle speed of 20 to 70 km / h; traffic level V represents the overload level, indicating that the applicable traffic conditions are a traffic volume of greater than 30 million equivalent axles or a vehicle speed of less than 20 km / h; and traffic level E represents the extremely heavy-load level, indicating that the applicable traffic conditions are a traffic volume of greater than 30 million equivalent axles and a vehicle speed of less than 20 km / h.

[0011] Preferably, according to the improved method for classifying the high-temperature performance of asphalt according to claim 1, the specific method for determining the high-temperature grade and applicable traffic grade of the asphalt to be evaluated in step S6 is as follows: the highest temperature applicable to both the original asphalt and the aged asphalt is taken as the high-temperature grade of the asphalt to be evaluated, and the highest traffic grade applicable to both the original asphalt and the aged asphalt at that temperature is taken as the applicable traffic grade of the asphalt.

[0012] By employing the above technical solution, the present invention provides an improved method for classifying the high-temperature performance of asphalt, which has at least the following beneficial effects: 1. This invention uses the MSCR test to evaluate the high-temperature performance of undisturbed asphalt, in order to... J nr3.2 As an evaluation indicator, compared to the rutting factor, J nr3.2 It can more accurately evaluate the high-temperature performance of undisturbed asphalt.

[0013] 2. Compared with existing performance grading systems, the asphalt high-temperature performance grading method proposed in this invention uses consistent evaluation indicators to assess the high-temperature performance of undisturbed and aged asphalt. By comparing the high-temperature grades of undisturbed and aged asphalt with the traffic grade classification results, the high-temperature grade and applicable traffic grade of the asphalt to be evaluated are determined.

[0014] 3. In the absence of aging equipment, the high-temperature performance of the original asphalt can be used to preliminarily determine the high-temperature grade and applicable traffic grade of the asphalt to be evaluated. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the improved asphalt high-temperature performance grading method of the present invention; Figure 2 The graph shows the shear strain of the original 70# base asphalt specimen used in Example 1 of this invention as a function of time at a temperature of 64°C and a creep stress level of 3.2 kPa. Figure 3 The graph shows the shear strain of the aged 70# base asphalt specimen used in Example 1 of this invention as a function of time at a temperature of 64°C and a creep stress level of 3.2 kPa. Figure 4 The graph shows the shear strain of the original SBS modified asphalt specimen used in Example 2 of this invention as a function of time at a temperature of 70°C and a creep stress level of 3.2 kPa. Figure 5 This is a graph showing the shear strain of the aged SBS modified asphalt specimen used in Example 2 of the present invention as a function of time at a temperature of 70°C and a creep stress level of 3.2 kPa. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding and implementation of how the present application uses technical means to solve technical problems and achieve technical effects.

[0017] Example 1 To address the technical problem that the rutting factor is insufficient to accurately evaluate the high-temperature performance of asphalt in existing high-temperature performance grading methods, this invention proposes an improved high-temperature performance grading method for asphalt. This method uses the MSCR test to evaluate the high-temperature performance of virgin and aged asphalt, in order to... J nr3.2As an evaluation indicator, the high-temperature rating and applicable traffic class of undisturbed asphalt and aged asphalt are classified based on different judgment criteria. Compared with the rutting factor, J nr3.2 This invention enables a more accurate evaluation of the high-temperature performance of undisturbed asphalt. By comparing the high-temperature ratings of undisturbed and aged asphalt with the traffic classification results, the high-temperature rating and applicable traffic class of the asphalt are determined. Compared with existing performance grading systems, the asphalt high-temperature performance grading method proposed in this invention uses consistent evaluation indicators to assess the high-temperature performance of undisturbed and aged asphalt, enabling a more accurate classification of the asphalt's high-temperature rating. The specific method is as follows: S1. In this embodiment, 70# base asphalt is used as the research object. The asphalt is subjected to short-term aging treatment by a rotating thin film heating test to obtain aged asphalt. The original asphalt and the aged asphalt are heated to a flowing state, and the original asphalt specimens and the aged asphalt specimens with a diameter of 25mm are prepared by the silicone mold method. After the asphalt specimens cool, they are demolded for use.

[0018] S2. Based on the type of asphalt, the initial test temperature was selected as 64°C. A dynamic shear rheometer was used to conduct MSCR tests on the undisturbed asphalt specimens at 64°C. After the MSCR test, a graph showing the shear strain of the undisturbed asphalt specimens over time at a creep stress level of 3.2 kPa was plotted, as shown below. Figure 1 As shown. Based on formulas (1) and (2), the average unrecoverable creep compliance of the original asphalt specimen at a creep stress level of 3.2 kPa was calculated. J nr3.2 , J nr3.2 The calculated value is 7.50 kPa. −1 .

[0019] (1) (2) In the formula: N Number of creep recovery cycles; J nr (3.2, N The asphalt specimen under a creep stress level of 3.2 kPa was at the [missing information - likely a specific stress level]. N The irreversible creep compliance at the end of the creep recovery cycle; ε 0 represents the shear strain of the asphalt specimen at the beginning of the creep stage in a single creep recovery cycle; ε r The shear strain of the asphalt specimen at the end of the recovery phase in a single creep recovery cycle.

[0020] S3. Judging the original asphalt specimen J nr3.2Is the calculated value less than or equal to 10 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was conducted again to determine the high-temperature rating and applicable traffic class of the original asphalt sample. The specific steps included the following: If in step S2 J nr3.2 Calculated value greater than 10 kPa −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until... J nr3.2 Calculated value less than or equal to 10 kPa −1 ; If in step S2 J nr3.2 The calculated value is greater than 4.4 kPa. −1 And less than or equal to 10 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 2.2 kPa. −1 And less than or equal to 4.4 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 1.1 kPa. −1 And less than or equal to 2.2 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is less than or equal to 1.1 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... Jnr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C.

[0021] In this embodiment, because the original asphalt specimen was at 64°C J nr3.2 The calculated value is greater than 4.4 kPa. −1 And less than or equal to 10 kPa −1 This indicates that the asphalt is suitable for 64°C, and the applicable traffic class at 64°C is S. The test temperature was increased to 70°C in 6°C increments, and the MSCR test at 70°C was conducted on the original asphalt specimen using a dynamic shear rheometer. After the MSCR test, the average non-recoverable creep compliance of the original asphalt specimen at a creep stress level of 3.2 kPa was calculated according to formulas (1) and (2). J nr3.2 , J nr3.2 The calculated value is 17.61 kPa. −1 Because the original asphalt specimen was at 70°C J nr3.2 Calculated value greater than 10 kPa −1 This indicates that the asphalt is no longer suitable for temperatures of 70°C and above.

[0022] S4. Based on the high-temperature rating of the original asphalt sample, a test temperature of 64°C was selected. A dynamic shear rheometer was used to conduct MSCR tests on the aged asphalt specimens at 64°C. After the MSCR test, a graph showing the shear strain of the aged asphalt specimens over time at a creep stress level of 3.2 kPa was plotted, as shown below. Figure 2 As shown. Based on formulas (1) and (2), the average unrecoverable creep compliance of the aged asphalt specimen at a creep stress level of 3.2 kPa was calculated. J nr3.2 , J nr3.2 The calculated value is 3.38 kPa. −1 .

[0023] S5. Judging the aging of asphalt specimens J nr3.2 Is the calculated value less than or equal to 4.5 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was conducted again to determine the high-temperature rating and applicable traffic class of the aged asphalt. The specific steps included the following: If in step S4 J nr3.2 The calculated value is greater than 4.5 kPa. −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until...J nr3.2 The calculated value is less than or equal to 4.5 kPa. −1 ; If in step S4 J nr3.2 Calculated value greater than 2 kPa −1 And less than or equal to 4.5 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 Calculated value greater than 1 kPa −1 And less than or equal to 2 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is greater than 0.5 kPa. −1 And less than or equal to 1 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is less than or equal to 0.5 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C.

[0024] In this embodiment, because the aged asphalt specimens were at 64°C J nr3.2 Calculated value greater than 2 kPa −1 And less than or equal to 4.5 kPa −1This indicates that the asphalt is suitable for 64°C, and the applicable traffic class at 64°C is S. The test temperature was increased to 70°C in 6°C increments, and the MSCR test at 70°C was conducted on the aged asphalt specimens using a dynamic shear rheometer. After the MSCR test, the average non-recoverable creep compliance of the aged asphalt specimens at a creep stress level of 3.2 kPa was calculated according to formulas (1) and (2). J nr3.2 , J nr3.2 The calculated value is 8.06 kPa. −1 Due to the aging of asphalt specimens at 70°C J nr3.2 The calculated value is greater than 4.5 kPa. −1 This indicates that the asphalt is no longer suitable for temperatures of 70°C and above.

[0025] S6. By comparing the high temperature rating and traffic rating of the original asphalt and the aged asphalt, in this embodiment, the performance rating of the 70# base asphalt is determined to be PG 64S−XX, where XX represents the low temperature rating of the asphalt, which needs to be determined by the asphalt flexural creep stiffness test.

[0026] It is important to note that the different traffic levels correspond to different types of aged asphalt. J nr3.2 The scope is based on AASHTO M 332, and includes the original asphalt samples corresponding to various traffic levels. J nr3.2 The scope is determined based on the following steps, not arbitrarily: A1. Select a base asphalt that meets the following requirements: its rutting factor in the aged state is approximately 2.2 times that in the original state. A2. Based on the linear viscoelastic theory, the calculation formulas for the dissipated strain energy of asphalt in the dynamic shear test and the calculation formulas for the shear deformation of asphalt in the creep stage in the MSCR test are derived as follows; (3) (4) In the formula: W To dissipate strain energy; τ 0 represents the amplitude of the shear stress applied in the dynamic shear test; | G *| represents the dynamic shear modulus; δ It is the phase angle; η 0 represents zero shear viscosity; ω It is the angular frequency, which is equal to 10 rad / s in the dynamic shear test; t It's the loading time; ε ( t ) is shear strain;J 0 represents instantaneous creep compliance; ΔJ ( t ) is a transient creep compliance; A3. Conduct MSCR tests on aged asphalt specimens at multiple temperatures, and calculate the MSCR at different temperatures according to the formula in step A2. J nr3.2 The corresponding zero-shear viscosity value was determined, and the Arrhenius equation and other methods were used for fitting to confirm it. J nr3.2 4.5 kPa −1 2kPa −1 1kPa −1 0.5 kPa −1 The corresponding temperature at that time; A4. At the four temperatures determined in step A3, conduct MSCR tests on the undisturbed asphalt specimens respectively, and calculate the MSCR values ​​of the undisturbed asphalt specimens at each temperature. J nr3.2 This allows for the determination of the corresponding traffic levels for each type of original asphalt sample. J nr3.2 scope.

[0027] Example 2 An improved method for classifying the high-temperature performance of asphalt is basically the same as the steps in Example 1, except that this example uses SBS modified asphalt as the research object.

[0028] MSCR tests were conducted on undisturbed asphalt specimens and aged asphalt specimens. The initial test temperature was 70°C, and the temperature was increased in 6°C increments until it reached 82°C. The shear strain of the undisturbed asphalt specimens at 70°C and a creep stress level of 3.2 kPa is shown in the figure below. Figure 4 As shown in the figure, the shear strain of the aged asphalt specimen at a temperature of 70°C and a creep stress level of 3.2 kPa varies with time. Figure 5 As shown.

[0029] Uncirculated asphalt specimens and aged asphalt specimens at various test temperatures J nr3.2 The calculated values ​​and corresponding traffic levels are shown in Table 1.

[0030] Table 1 Summary of MSCR test results for SBS modified asphalt Comparing the high-temperature rating and traffic class classification results of undisturbed asphalt and aged asphalt, in this embodiment, the performance class of the SBS modified asphalt is determined to be PG 82S−XX, where XX represents the low-temperature rating of the asphalt, which needs to be determined through asphalt flexural creep stiffness test. Furthermore, the traffic class applicable to this SBS modified asphalt at 76°C is H, and the traffic class applicable at 70°C is E.

[0031] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0032] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Since the above embodiments are substantially similar to the method embodiments, their descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0033] The above embodiments provide a detailed description of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An improved method for classifying the high-temperature performance of asphalt, characterized in that, The method includes the following steps: S1. After subjecting the asphalt to be evaluated to short-term aging treatment, prepare original asphalt specimens and aged asphalt specimens respectively. S2. Select the initial test temperature according to the type of asphalt, and conduct MSCR tests on the undisturbed asphalt specimens at this temperature. Obtain the data on the change of shear strain over time in the MSCR test to calculate the average unrecoverable creep compliance of the undisturbed asphalt specimens at a creep stress level of 3.2 kPa. J nr3.2 ; S3. Judging the original asphalt specimen J nr3.2 Is the calculated value less than or equal to 10 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was conducted again to determine the high temperature rating and applicable traffic rating of the original asphalt sample. S4. Based on the high-temperature grade of the original asphalt, select the initial test temperature and conduct MSCR tests on the aged asphalt specimens at this temperature. Obtain the data on the change of shear strain over time in the MSCR test to calculate the average unrecoverable creep compliance of the aged asphalt specimens at a creep stress level of 3.2 kPa. J nr3.2 ; S5. Judging the aging of asphalt specimens J nr3.2 Is the calculated value less than or equal to 4.5 kPa at the current test temperature? −1 Based on this, the test temperature was changed and the MSCR test was conducted again to determine the high temperature rating and applicable traffic level of the aged asphalt. S6. Based on the high temperature rating and traffic rating of the original asphalt and aged asphalt, determine the high temperature rating and applicable traffic rating of the asphalt to be evaluated.

2. The improved method for classifying the high-temperature performance of asphalt according to claim 1, characterized in that, The average non-recoverable creep compliance at a creep stress level of 3.2 kPa J nr3.2 The calculation formula is: In the formula: N Number of creep recovery cycles; J nr (3.2, N The asphalt specimen under a creep stress level of 3.2 kPa was at the [missing information - likely a specific stress level]. N The irreversible creep compliance at the end of the creep recovery cycle; ε 0 represents the shear strain of the asphalt specimen at the beginning of the creep stage in a single creep recovery cycle; ε r The shear strain of the asphalt specimen at the end of the recovery phase in a single creep recovery cycle.

3. The improved method for classifying the high-temperature performance of asphalt according to claim 1, characterized in that, In step S3, the method for determining the high-temperature grade and applicable traffic grade of the original asphalt sample is as follows: If in step S2 J nr3.2 Calculated value greater than 10 kPa −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until... J nr3.2 Calculated value less than or equal to 10 kPa −1 ; If in step S2 J nr3.2 The calculated value is greater than 4.4 kPa. −1 And less than or equal to 10 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 2.2 kPa. −1 And less than or equal to 4.4 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step distance until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is greater than 1.1 kPa. −1 And less than or equal to 2.2 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C; If in step S2 J nr3.2 The calculated value is less than or equal to 1.1 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 Calculated value greater than 10 kPa −1 Or the test temperature reaches 82°C.

4. The improved method for classifying the high-temperature performance of asphalt according to claim 1, characterized in that, In step S5, the method for determining the high-temperature rating and applicable traffic class of aged asphalt is as follows: If in step S4 J nr3.2 The calculated value is greater than 4.5 kPa. −1 Then, the test temperature is reduced according to the preset step distance, and the MSCR test is carried out on the asphalt again until... J nr3.2 The calculated value is less than or equal to 4.5 kPa. −1 ; If in step S4 J nr3.2 Calculated value greater than 2 kPa −1 And less than or equal to 4.5 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as S, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step distance, until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 Calculated value greater than 1 kPa −1 And less than or equal to 2 kPa −1 If the applicable traffic class of the asphalt at the current temperature is recorded as H, then the MSCR test on the asphalt will be conducted again by increasing the test temperature according to the preset step distance until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is greater than 0.5 kPa. −1 And less than or equal to 1 kPa −1 If the traffic class applicable to the asphalt at the current temperature is recorded as V, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C; If in step S4 J nr3.2 The calculated value is less than or equal to 0.5 kPa. −1 If the traffic class applicable to the asphalt at the current temperature is recorded as E, the MSCR test will be conducted on the asphalt again by increasing the test temperature according to the preset step increments until... J nr3.2 The calculated value is greater than 4.5 kPa. −1 Or the test temperature reaches 82°C.

5. The improved method for classifying the high-temperature performance of asphalt according to claim 1, characterized in that, In steps S3 and S5, traffic level S represents the standard level, indicating that the applicable traffic conditions are a traffic volume of less than 10 million equivalent axles and a vehicle speed of more than 70 km / h; traffic level H represents the heavy-load level, indicating that the applicable traffic conditions are a traffic volume of 10 million to 30 million equivalent axles or a vehicle speed of 20 to 70 km / h; traffic level V represents the overload level, indicating that the applicable traffic conditions are a traffic volume of more than 30 million equivalent axles or a vehicle speed of less than 20 km / h; and traffic level E represents the extremely heavy-load level, indicating that the applicable traffic conditions are a traffic volume of more than 30 million equivalent axles and a vehicle speed of less than 20 km / h.

6. The improved method for classifying the high-temperature performance of asphalt according to claim 1, characterized in that, In step S6, the specific method for determining the high temperature grade and applicable traffic grade of the asphalt to be evaluated is as follows: the highest temperature that is commonly applicable to both the original asphalt and the aged asphalt is taken as the high temperature grade of the asphalt to be evaluated, and the highest traffic grade that is commonly applicable to both the original asphalt and the aged asphalt at that temperature is taken as the applicable traffic grade of the asphalt.

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