A method for selecting key characterization parameters for phase state structure transition of time-aging SBS modified asphalt

Abstract

The application relates to a method for selecting key characterization parameters of phase state structure transition of aging SBS modified asphalt, and relates to a method for selecting key characterization parameters of phase state structure transition of aging SBS modified asphalt. The application aims to solve the technical problem that there is no characterization parameter for phase state structure transition in the aging process of SBS modified asphalt. The application carries out fluorescence microscopic testing, viscoelastic testing, viscous flow testing and viscous toughness testing on SBS modified asphalt with different aging times; the aging time period t corresponding to the obvious change of the phase state structure is obtained through the fluorescence microscopic testing, then the change rates of the maximum value and the minimum value in the result parameters of the viscoelastic testing, the viscous flow testing and the viscous toughness testing within the aging time period t are calculated, and the parameter with the change rate greater than 80% is taken as the key characterization parameter of the phase state structure transition.

Description

Technical Field

[0001] This invention relates to a method for selecting key characterization parameters for the phase structure transformation of aged SBS modified asphalt. Background Technology

[0002] Asphalt is widely used in roads and pavements due to its low cost, relative ease of application, and good mechanical properties under load. However, asphalt performance is challenged when the material needs to operate outside a specific temperature range. Asphalt ruts at high temperatures and cracks at low temperatures. Therefore, to ensure reliable performance of asphalt under varying environmental conditions, different climates, and processing parameters, its operating temperature range must be extended. To broaden the operating temperature range and increase the service life of asphalt pavements, styrene-butadiene-styrene block copolymer (SBS) is often added to blends due to its good temperature stability. Furthermore, SBS thermoplastic elastomers provide excellent stiffness and elastic recovery, attributed to the network of glassy polystyrene polymer chains embedded in a rubbery polybutadiene matrix.

[0003] Although SBS-modified asphalt exhibits superior performance compared to base asphalt, whether it can retain this excellent performance after aging remains questionable. In other words, it is uncertain whether aged SBS-modified asphalt will retain its characteristics as modified asphalt or revert to the state of base asphalt. Understanding the phase structure changes in aged SBS-modified asphalt helps identify different aging states, reveal deterioration patterns, and provide practical guidance for pavement maintenance and asphalt recycling. Despite extensive discussions of the phase structure of SBS-modified asphalt in past studies, the evolution pattern of phase structure during aging remains uncertain, with one major problem being the confusion surrounding the concept of phase structure.

[0004] Phase structure is generally considered a multidimensional concept with multiple dimensions and aspects, including morphological structure, material structure, chemical structure, mechanical properties, and rheological properties, which have been extensively studied in many research studies. Currently, researchers mainly study the viscous flow properties, viscoelastic properties, elastic recovery, and viscoductile properties of SBS-modified asphalt for characteristic identification. The slope (VTS) of the viscosity-temperature curve can be obtained through rotational viscosity testing; the percentage (ER) of recovery to initial conditions after elongation and the average elastic recovery rate (ERR) can be calculated through elastic recovery testing; and the recovery rate (R) and irrecoverable creep rate (J) can be calculated through multiple stress repeated creep recovery (MSCR) testing. nr The viscosity and toughness parameters T of the material were obtained through viscosity and toughness tests. oand toughness parameter T e And so on. Some of these methods can qualitatively evaluate the modification effect of modified asphalt, but they cannot quantify it, and simply judging changes in performance indicators cannot reveal the aging mechanism. Experimental parameters and performance coefficients are complex and varied. After SBS modified asphalt ages, all of the above indicators show varying degrees of decay. In conventional testing methods, only some parameters conform to the true decay law. Therefore, it is essential to find the key characterizing parameters of phase structure transformation at different aging stages of SBS modified asphalt. Summary of the Invention

[0005] The present invention aims to solve the technical problem of the lack of characterization parameters for the phase structure transformation during the aging process of SBS modified asphalt, and provides a method for selecting key characterization parameters for the phase structure transformation of SBS modified asphalt in the time-phase aging stage.

[0006] The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to the present invention is carried out according to the following steps:

[0007] First, samples of the SBS modified asphalt to be tested were prepared and subjected to time-sequential thermo-oxidative aging. Then, fluorescence microscopy, viscoelasticity, viscous flow, and visco-toughness tests were performed on the SBS modified asphalt at different aging times. The aging time period t corresponding to the significant change in the phase structure of the SBS modified asphalt was determined by fluorescence microscopy. Then, the rate of change of the maximum and minimum values ​​of the parameters in the viscoelasticity, viscous flow, and visco-toughness tests within the aging time period t was calculated. Parameters with a rate of change greater than 80% were used as key characterization parameters of the phase structure transformation of aged SBS modified asphalt, parameters with a rate of change greater than 60% and less than or equal to 80% were used as reference characterization parameters of the phase structure transformation of aged SBS modified asphalt, and parameters with a rate of change less than or equal to 60% were not used as characterization parameters of the phase structure transformation of aged SBS modified asphalt.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] The method of this invention fully conforms to the true decay law of phase structure evolution of aged SBS modified asphalt, with high accuracy. Compared with other methods, it can reduce time and material consumption. This method is very suitable for characterizing the phase structure evolution of aged SBS modified asphalt. Finally, it is recommended to use the viscosity-toughness curve parameter as one of the key indicators for determining whether aged asphalt can be regarded as modified asphalt or conventional asphalt. Attached Figure Description

[0010] Figure 1 The fluorescence image is from the 0-hour aging period in Experiment 2.

[0011] Figure 2 The fluorescence image is from the second experiment after 2 hours of aging.

[0012] Figure 3 The fluorescence image is from the 4-hour aging test in Experiment 2.

[0013] Figure 4 The fluorescence image is from the 6-hour aging period in Experiment 2.

[0014] Figure 5 The fluorescence image is from the 8-hour aging period in Experiment 2.

[0015] Figure 6 The image shows the fluorescence of the unaged matrix bitumen in Experiment 2;

[0016] Figure 7 The viscosity-temperature curves from Experiment 3;

[0017] Figure 8 To Figure 7 Material temperature sensitivity curve;

[0018] Figure 9 The data graph for the loss modulus G in Experiment 4 is shown.

[0019] Figure 10 for Figure 9 Enlarged view within the Chinese box;

[0020] Figure 11 The graph shows the ER data from Experiment 5;

[0021] Figure 12 The graph shows the ERR data from Experiment 5;

[0022] Figure 13 The data used to fit the experimental results to the Burgers model in Experiment 6. Figure 1 ;

[0023] Figure 14 The data used to fit the experimental results to the Burgers model in Experiment 6. Figure 2 ;

[0024] Figure 15 The data used to fit the experimental results to the Burgers model in Experiment 6. Figure 3 ;

[0025] Figure 16 The data used to fit the experimental results to the Burgers model in Experiment 6. Figure 4 ;

[0026] Figure 17 The load-deformation curves from Experiment 7;

[0027] Figure 18 The thermogram for test eight. Detailed Implementation

[0028] Specific Implementation Method 1: This implementation method is a method for selecting key characterization parameters for phase structure transformation during the time-aged SBS modified asphalt stage, specifically carried out according to the following steps:

[0029] First, samples of the SBS modified asphalt to be tested were prepared and subjected to time-sequential thermo-oxidative aging. Then, fluorescence microscopy, viscoelasticity, viscous flow, and visco-toughness tests were performed on the SBS modified asphalt at different aging times. The aging time period t corresponding to the significant change in the phase structure of the SBS modified asphalt was determined by fluorescence microscopy. Then, the rate of change of the maximum and minimum values ​​of the parameters in the viscoelasticity, viscous flow, and visco-toughness tests within the aging time period t was calculated. Parameters with a rate of change greater than 80% were used as key characterization parameters of the phase structure transformation of aged SBS modified asphalt, parameters with a rate of change greater than 60% and less than or equal to 80% were used as reference characterization parameters of the phase structure transformation of aged SBS modified asphalt, and parameters with a rate of change less than or equal to 60% were not used as characterization parameters of the phase structure transformation of aged SBS modified asphalt.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the time-sharing thermo-oxidative aging method is aging in a rotating thin-film oven. Everything else is the same as in Specific Implementation Method One.

[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the viscoelastic test is an elastic recovery test and a multi-stress repeated creep recovery test. Everything else is the same as in Specific Implementation Method One or Two.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the viscous flow test is a rotational viscosity test and a dynamic shear rheology test. Everything else is the same as in Specific Implementation Methods One to Three.

[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Two in that the method for preparing the SBS modified asphalt sample and performing time-sequential thermo-oxidative aging is as follows:

[0034] 1. The base bitumen and SBS are sheared at high temperature;

[0035] 2. Mechanically stir the materials at high temperature;

[0036] 3. Add stabilizer and stir continuously at high temperature;

[0037] IV. The samples were placed in a high-temperature rolling film oven and kept at that temperature for different times to prepare SBS modified asphalt with different aging times; this process was carried out in air at an airflow rate of 5000 mL / min ± 200 mL / min. Everything else is the same as in Specific Implementation Method 1. Everything else is the same as in Specific Implementation Method 2.

[0038] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Three in that it uses the Burgers model to fit and analyze the elastic recovery performance of time-aged SBS modified asphalt based on the results of the multi-stress repeated creep recovery test. Everything else is the same as in Specific Implementation Method Three.

[0039] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the Burgers model described is...

[0040]

[0041] In the formula: ε(t) is the cumulative strain, in meters (m);

[0042] σ0 represents the stress level, measured in kPa.

[0043] t represents the loading time, measured in seconds (s).

[0044] E1 is the elastic coefficient in the Maxwell model, and η1 is the damping coefficient in the Maxwell model.

[0045] E2 is the elastic coefficient in the Kelvin model, and η2 is the damping coefficient in the Kelvin model. Everything else is the same as in Specific Implementation Method Six.

[0046] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that it extracts parameters from the curve obtained by the viscosity-toughness test. The specific method is as follows:

[0047] 1. The viscosity-toughness of SBS modified asphalt under timed aging was tested according to ASTM D5801 standard, and the load-deformation curve was obtained.

[0048] II. Following the polymer yield and fracture theory, the load-deformation curve is divided into different regions: elastic deformation region, yield point, strain softening stage, cold drawing stage, stress hardening stage, and fracture point.

[0049] III. Extraction of Elastic Deformation Region and Calculation of Elastic Modulus (E) and Elastic Ultimate Strength (σ) A ); Yield point extracts yield strength (σ) Y ); Extracting fracture strength (σ) from the fracture point B ) and elongation at break (ε B ); line integral T o and T eThis indicates the material's viscoductile and ductile properties and its resistance to fracture. Other aspects are the same as in Specific Implementation Method Seven.

[0050] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Five in that the stabilizer mentioned in step three is elemental sulfur. Everything else is the same as in Specific Implementation Method Five.

[0051] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Five in that the high temperature mentioned in step four is 180°C. Everything else is the same as in Specific Implementation Method Five.

[0052] The invention was verified using the following experiments:

[0053] Experiment 1: This experiment used 70# base asphalt and SBS modified asphalt (ID). SBS modified asphalt (ID) was prepared using 70# base asphalt, linear SBS1301 modifier, and stabilizer. SBS1301, provided by Yanshan Petrochemical Company, is a linear copolymer with an average molecular weight of 100,000 g / mol and a styrene content of 30 wt%. Commercially available elemental sulfur was added to the SBS modified asphalt as a stabilizer to achieve chemical crosslinking. A 5% SBS content was used to match actual conditions, and the RTFOT delayed aging method was used to simulate the aging process. The specific steps for preparing time-aged SBS modified asphalt included:

[0054] 1. Add 5wt% linear SBS1301 to 70# base bitumen and shear at 4000rpm for 0.5h at 180℃;

[0055] 2. Mechanically stir the material at 180℃ and a stirring rate of 500 rpm for 1 hour;

[0056] 3. Add 0.15wt% stabilizer and stir continuously at 180℃ for 1.5h;

[0057] IV. Place the samples in a 180℃ rolling film oven and keep them at that temperature for 2h, 4h, 6h and 8h respectively to prepare specimens with different aging degrees; this process is carried out in air with an airflow of 5000mL / min±200mL / min.

[0058] Experiment 2: Fluorescence microscopy testing includes the following steps:

[0059] I. The phase structure morphology of the SBS modified asphalt and 70# base asphalt prepared above was characterized by fluorescence microscopy. Fluorescence images at different aging stages were collected using a CSM-900E series fluorescence microscope.

[0060] 2. SBS modified bitumen was observed under a fluorescence microscope at 400× magnification, and test samples were prepared using hot-drop coverslips.

[0061] III. Observe the dispersed phase, continuous phase, and discontinuous phase of the SBS copolymer, such as... Figure 1-5 As shown, Figure 1-5 Fluorescence images corresponding to aging times of 0h, 2h, 4h, 6h, and 8h, respectively. Figure 6 The fluorescence image shows the base asphalt before aging, and can be seen from 4 to 6 hours of RTFOT aging of SBS modified asphalt (i.e., Figure 3 and Figure 4 The phase structure of asphalt underwent significant changes, with the polymer network structure disappearing noticeably and the amount of SBS decreasing significantly.

[0062] Experiment 3: The viscosity flow test analysis method includes the following steps:

[0063] I. The rotational viscosity of SBS modified asphalt at different aging stages was tested using a rotational viscometer (RV), and viscosity-temperature curves were plotted.

[0064] II. Fit the viscosity-temperature curve using the modified Refutas curve (ASTM 2017b): loglog(η)=n-VTSlog(T);

[0065] Where: η is the viscosity of SBS modified asphalt; N is the regression coefficient; T is the test temperature in °C; and the slope of the regression line VTS represents the temperature sensitivity performance.

[0066] Figure 7 The viscosity-temperature curve of the material. Figure 8 To Figure 7 The material temperature sensitivity curves show that the VTS value increases with the extension of aging time. The VTS values ​​for 0h, 2h, 4h, 6h, and 8h of aging are -1.191, -1.192, -1.188, -1.033, and -0.946, respectively. The change rate of the VTS value for 2h and 4h is 13.05%.

[0067] Experiment 4: Low-Temperature Phase Behavior Analysis includes the following steps:

[0068] I. The viscoelastic phase behavior of SBS modified asphalt was studied by dynamic mechanical analysis using a dynamic shear rheometer test. Temperature scans were performed at a constant frequency of 1.592 Hz within a temperature range of -10℃ to 70℃, with 10℃ intervals. A fixed strain of 0.1% was selected within the linear viscoelastic range. A parallel plate geometry of 8 mm with a 2 mm gap was used within the temperature range of -10℃ to 30℃, and a parallel plate geometry of 25 mm with a 1 mm gap was used within the temperature range of 40℃ to 70℃. The detailed test procedure was based on ASTM D7175 (ASTM 2015b).

[0069] II. The loss modulus G method is used to determine the Tg temperature, such as Figure 9 and 10 As shown, Figure 10 for Figure 9 The enlarged view within the Chinese box shows that the glass transition temperatures (Tg) of SBS aged asphalt at RTFOT0h, 2h, 4h, 6h, and 8h are -3.2℃, -1.1℃, 3.1℃, 5.2℃, and 6.8℃, respectively. The Tg change rate for 2h and 4h is 67.74%.

[0070] Test 5: The elastic recovery test includes the following steps:

[0071] 1. Elastic recovery test was performed using a ductility tester according to ASTM D 6084 (ASTM 2010).

[0072] II. Calculate the elongation ER and elastic recovery rate ERR, such as Figure 11 and 12 As shown.

[0073]

[0074]

[0075] In the formula: x is the remaining length of the asphalt sample, in cm;

[0076] ER (elongation at break) is the percentage of a material that recovers to its initial condition after stretching, expressed as a percentage.

[0077] ERR (elastic recovery rate) is the average rate of change of elastic recovery over the time interval from t1 to t2, expressed in % / min.

[0078] ER1 and ER2 are the elongation rates corresponding to measurement times t1 and t2, respectively, in percentage (%).

[0079] t1 and t2 are the selected time points, in minutes.

[0080] Table 1 ER Data (%)

[0081]

[0082] Table 2 ERR Data

[0083] Time range 0h 2h 4h 6h 8h 0-5min 13 11.6 9.4 8 7.4 0-10min 7.1 6.7 5.7 5 4.5 0-20min 0.8 0.8 0.7 0.8 0.7 20-30min 0.4 0.4 0.5 0.4 0.4 30-40min 0.4 0.3 0.3 0.3 0.3 40-50min 0.3 0.2 0.2 0.2 0.2 50-60min 0.2 0.2 0.2 0.1 0.2

[0084] Since ER data doesn't clearly differentiate between different stages of the aging process, ERR data is calculated instead. The difference lies in the fact that ER data is cumulative, while ERR data is segmented, calculating only a specific time range. To distinguish between instantaneous elastic recovery and delayed elastic recovery, the 60-minute period is divided into seven time segments in the ERR table. The first three segments represent instantaneous elastic recovery, and the last four represent delayed elastic recovery. From this table, we can see that the ERR is almost zero in the 0-20 minute range, while the ERR value is still relatively large in the 0-10 minute range. This indicates that the time range for calculating instantaneous elastic recovery should be between 10 and 20 minutes.

[0085] Test 6: The Multi-Stress Repeated Creep Recovery (MSCR) test includes the following steps:

[0086] I. Multi-stress repeated creep recovery (MSCR) tests were conducted using a dynamic shear rheometer. The tests were performed at 64°C using two stresses (0.1 kPa and 3.2 kPa). The loading process consisted of 20 cycles (10 cycles at 0.1 kPa and 10 cycles at 3.2 kPa), with each cycle including 1 second of creep and 9 seconds of recovery (ASTM D7405, ASTM 2015c).

[0087] 2. The Burgers model was used to fit the experimental results to obtain the instantaneous elastic compliance J. e Viscous flexibility J v and hysteresis elastic flexibility J d All units are in kPa -1 ,like Figure 13 and 14 As shown.

[0088] III. Calculation of instantaneous elastic component J e' Viscous component J v' and the hysteretic elastic component J de' All units are %; V r This is the ratio of viscous flexibility to elastic flexibility, such as... Figure 15 and 16 As shown.

[0089] The Burgers model is:

[0090] In the formula: ε(t) is the cumulative strain, in meters;

[0091] σ0 represents the stress level, measured in kPa.

[0092] t represents the loading time, measured in seconds (s).

[0093] E1 is the elastic coefficient in the Maxwell model, and η1 is the damping coefficient in the Maxwell model.

[0094] E2 is the elastic coefficient in the Kelvin model, and η2 is the damping coefficient in the Kelvin model;

[0095] The total deformation in creep tests is classified into three types:

[0096] a) Instantaneous elastic deformation; b) Delayed elastic deformation; c) Viscous deformation; described as:

[0097]

[0098]

[0099]

[0100]

[0101]

[0102] In the formula: J(t) is the total creep compliance, in kPa. -1 ;

[0103] J e J v and J de The parameters are, in order, instantaneous elastic flexibility, viscous flexibility, and hysteretic elastic flexibility, with units of kPa. -1 ;

[0104] J e' J v' J de' The components are, in order, the instantaneous elastic component, the viscous component, and the hysteretic elastic component, representing the percentage of total deformation, in %;

[0105] V r It is the ratio of viscous flexibility to elastic flexibility.

[0106] Experiment 7: Viscosity and toughness test includes the following steps:

[0107] I. Experimental Procedure: The experiment was conducted according to ASTM D 5801 (ASTM 2017c) standard, specifically as follows: The asphalt sample was treated in an oven at 80℃ for 1 hour, and then 50g ± 1g of the sample was poured into a test container for preparation. The sample (using the test container) was placed in a water bath at 25℃ for 1.5 hours, and then stretched at 25℃ with a loading rate of 500mm / min to obtain the load-deformation curve of the time-aged SBS modified asphalt.

[0108] II. Extract the elastic modulus (E) and elastic ultimate strength (σ) from the load-deformation curve. A ), yield strength (σ) Y ), fracture strength (σ) B ), elongation at break (ε) B ), line integral T o (The entire integral area of ​​the curve) and T e (Toughness parameters) Related parameters, such as Figure 17 As shown;

[0109] III. The parameters were extracted for SBS modified asphalt after RTFOT aging for 0h, 2h, 4h, 6h, and 8h, and for base asphalt after RTFOT aging for 0h and 8h, as shown in Table 3. It can be observed that the shape of the toughness curve and related parameters significantly differentiate the aging behavior of SBS modified asphalt. From a toughness perspective, the curve shape of SBS modified asphalt after 6h of RTFOT (rotary thin-film oven aging) is exactly the same as that of conventional asphalt, which is consistent with the changes observed in fluorescence microscopy. The change rate of Te at 2h and 4h is 100%. The parameters of the toughness curve can be used to determine whether the aged SBS modified asphalt can be treated as modified asphalt or conventional asphalt.

[0110] Table 3 Mechanical parameters of the toughness curve

[0111]

[0112] Experiment 8: To evaluate the applicability of the above quantitative parameters in describing phase evolution and performance degradation during aging, correlation analysis was performed using the most relevant parameters from the above experiments. The results showed that... Figure 18 The correlation heatmap illustrates this, where -1 and 1 represent strong negative and positive correlations, respectively, and values ​​close to 0 indicate no correlation. The correlation heatmap shows robust correlations between many indicators and aging time, indicating a significant linear trend during the aging process.

[0113] The method for fitting MSCR test results using the Burgers model provided in this invention shows that aged SBS modified asphalt exhibits a lower viscosity ratio and superior elasticity, confirming the reliability of evaluating the elastic recovery performance of aged SBS modified asphalt in the experiment. Delayed elastic deformation (J) de' The percentage of total deformation did not differ significantly at different aging times, which is consistent with the results of the elastic recovery test.

[0114] This invention extracts different quantitative parameters from the visco-toughness curve. Excluding the visco-toughness parameter To, which exhibits a non-linear behavior of first increasing and then decreasing, showing a weak correlation, other quantifiable parameters in the toughness curve show a strong correlation with aging. Compared to different properties, the toughness curve not only provides a comprehensive set of parameters but also effectively distinguishes the critical states of modified and unmodified asphalt during the aging process, possessing clear physical significance. Therefore, this method is highly suitable for characterizing the phase structure evolution of aged SBS modified asphalt.

[0115] Table 4 shows the rate of change of the above test data.

[0116]

[0117] As can be seen from Table 4, the indicators with a change rate greater than 80% are the toughness parameter Te and the fracture elongation ε. B The change rates were 100.00% and 86.84%, respectively, and are recommended as key characterization parameters for the phase structure transformation of aged SBS modified asphalt. The change rates were between 60% and 80% for the glass transition temperature (Tg) and the visco-toughness parameter (To), with change rates of 67.74% and 71.29%, respectively, and are recommended as reference characterization parameters for the phase structure transformation of aged SBS modified asphalt. Change rates below 60% are not recommended as characterization parameters for the phase structure transformation of aged SBS modified asphalt.

Claims

1. A method for selecting key characterization parameters for phase structure transformation during time-aged SBS modified asphalt, characterized in that... The key characterization parameters for phase structure transformation in time-aged SBS modified asphalt were selected according to the following steps: First, samples of the SBS modified asphalt to be tested were prepared and subjected to time-sequential thermo-oxidative aging. Then, fluorescence microscopy, viscoelasticity, viscous flow, and visco-toughness tests were performed on the SBS modified asphalt at different aging times. The aging time period t corresponding to the significant change in the phase structure of the SBS modified asphalt was determined by fluorescence microscopy. Then, the rate of change of the maximum and minimum values ​​of the parameters in the viscoelasticity, viscous flow, and visco-toughness tests within the aging time period t was calculated. Parameters with a rate of change greater than 80% were used as key characterization parameters of the phase structure transformation of aged SBS modified asphalt, parameters with a rate of change greater than 60% and less than or equal to 80% were used as reference characterization parameters of the phase structure transformation of aged SBS modified asphalt, and parameters with a rate of change less than or equal to 60% were not used as characterization parameters of the phase structure transformation of aged SBS modified asphalt.

2. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 1, characterized in that... The time-division thermo-oxidative aging method is aging in a rotating thin-film oven.

3. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 1, characterized in that... The viscoelastic tests mentioned are elastic recovery tests and multi-stress repeated creep recovery tests.

4. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 1, characterized in that... The viscous flow test includes rotational viscosity test and dynamic shear rheology test.

5. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 2, characterized in that... The method for preparing the SBS modified asphalt sample and subjecting it to time-sequential thermo-oxidative aging is as follows:

1. The base bitumen and SBS are sheared at high temperature; 2. Mechanically stir the materials at high temperature; 3. Add stabilizer and stir continuously at high temperature; IV. The samples were placed in a high-temperature rolling film oven and kept at that temperature for different times to prepare SBS modified asphalt with different aging times. This process is carried out in air at a flow rate of 5000 mL / min ± 200 mL / min; The aforementioned high temperatures are all 180℃.

6. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 3, characterized in that... The Burgers model was used to fit and analyze the elastic recovery performance of time-aged SBS modified asphalt based on the results of multi-stress repeated creep recovery tests.

7. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 6, characterized in that... The Burgers model is ， In the formula: ε(t) is the cumulative strain, in meters (m); σ0 represents the stress level, measured in kPa. t represents the loading time, measured in seconds (s). E1 is the elastic coefficient in the Maxwell model, and η1 is the damping coefficient in the Maxwell model. E2 is the elastic coefficient in the Kelvin model, and η2 is the damping coefficient in the Kelvin model.

8. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 1, characterized in that... The parameters for extracting from the curves obtained from the viscosity-toughness test are as follows:

1. The viscosity-toughness of SBS modified asphalt under timed aging was tested according to ASTM D5801 standard, and the load-deformation curve was obtained. II. Following the polymer yield and fracture theory, the load-deformation curve is divided into different regions: elastic deformation region, yield point, strain softening stage, cold drawing stage, stress hardening stage, and fracture point. III. Extraction of elastic deformation region, calculation of elastic modulus and elastic ultimate strength; extraction of yield strength from yield point; extraction of fracture strength and elongation at fracture point; line integral T. o and T e This indicates the material's viscoductility and toughness, as well as its resistance to fracture.

9. The method for selecting key characterization parameters for phase structure transformation in time-aged SBS modified asphalt according to claim 5, characterized in that... The stabilizer mentioned in step three is elemental sulfur.

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