A method for quickly determining the true low-temperature grade and thermally reversible aging degree of asphalt

Abstract

The present invention discloses a method for rapidly determining the true low-temperature grading and degree of thermally reversible aging of asphalt, and relates to the technical field of road performance evaluation of petroleum asphalt. The present invention enables the asphalt binder to be tested to quickly reach an equilibrium state through cyclic oscillation thermal history treatment before the asphalt low-temperature bending beam rheology (BBR) test, thereby achieving rapid determination of the true low-temperature performance grading of asphalt and rapid differentiation of asphalts with different thermally reversible aging trends. At the same time, it can also rapidly identify the effects of various additives on the true low-temperature performance of asphalt. The present invention overcomes the problem of long time required for existing true low-temperature performance grading and thermally reversible aging evaluation of asphalt through cyclic oscillation thermal treatment of asphalt, and can achieve the same effect in only 20 hours, thereby accelerating the research and development process of thermally reversible aging-resistant asphalt, and can also quickly conduct quality acceptance, avoiding construction delays caused by long-term raw material quality testing and increased costs caused by asphalt storage.

Description

Technical Field

[0001] The present invention relates to the technical field of road performance evaluation of petroleum asphalt, and in particular to a method for rapidly determining the true low-temperature classification and thermally reversible aging degree of asphalt. Background Art

[0002] Asphalt-based materials are playing an increasingly important role in transportation infrastructure construction due to their waterproofing, vibration damping, and easy maintenance properties. Unlike cement-based materials, asphalt-based materials tend to harden or become brittle over their service life. Hardening significantly reduces the crack resistance and water stability of the surface asphalt material, making asphalt pavements susceptible to premature failure. The tendency of asphalt to harden under atmospheric influences is well known and has been studied for many years. The term "aging" is often used in engineering to describe the hardening of asphalt binders during storage, mixing, paving, and service. Thermally reversible aging is another important aging mode that is largely overlooked by researchers. This aging generally refers to the isothermal hardening phenomenon in which the stiffness of asphalt binders increases exponentially with storage time when stored at room or low temperatures. During this process, no chemical reaction occurs, and the stiffness of the asphalt binder can be restored to its original state by heating. Thermally reversible aging at low temperatures is also known as "physical hardening," while thermally reversible aging at moderate temperatures is also known as "spatial hardening." Existing research results from indoor and field test sections indicate that both thermally reversible aging and oxidative aging are equally important to the durability of asphalt binders, especially in cold regions. By considering the actual low-temperature performance grade of asphalt in equilibrium after thermally reversible aging, the asphalt's adaptability to low-temperature environments can be more accurately determined, thereby avoiding the premature cracking of asphalt pavements caused by the loss of asphalt's low-temperature performance grade during long-term low-temperature service. Furthermore, the degree of thermally reversible aging in asphalt is also a key indicator of asphalt's low-temperature performance. Lower levels of thermally reversible aging indicate that the asphalt's low-temperature performance is less affected by degradation from long-term low-temperature thermal history.

[0003] In order to quantify the degree of thermal reversible aging in asphalt binder, the existing patent application "A method for obtaining an evaluation index of the physical hardening performance of asphalt materials" (CN201510519493.4) ​​discloses a method for quantifying the degree of low-temperature thermal reversible aging of asphalt using the index of the slope of the time-shift factor curve. However, this method cannot be used to determine the actual low-temperature environment temperature that asphalt can adapt to, and the slope index of the time-shift factor curve cannot be linked to the existing asphalt low-temperature grading system, indicating the adverse effects of low-temperature thermal reversible aging on the durability of asphalt. At the same time, constant temperature storage of asphalt at different temperatures may result in different time-shift factor curve slopes. Therefore, this method and index cannot guide the selection of asphalt in cold regions. The patent "A method for calculating the temperature stress of binder considering the thermal reversible aging phenomenon of asphalt" (CN202110030431.2) discloses a method for calculating the temperature stress of asphalt considering the thermal reversible aging phenomenon. However, the testing process of this method is cumbersome, and the asphalt needs to be kept at a constant temperature for 72 hours to reach an equilibrium state before the temperature stress can be calculated. The patent "A method for quantifying the degree of thermally reversible aging of cold-recycled asphalt mixtures" (CN202211117456.7) discloses a method for quantifying the degree of thermally reversible aging in asphalt mixtures. However, this method is aimed at a composite material system of aggregate and binder, and the microcrack density proposed is not applicable to the asphalt binder itself. The patents "A test instrument and method for evaluating the physical hardening of asphalt" (CN202210561808.1) and "A method for evaluating the physical hardening of asphalt" (CN202210474811.X) respectively propose the use of cone penetration and atomic force microscopy images to quantify the low-temperature thermally reversible aging trend in asphalt. However, similar to the previous analysis, these two methods cannot be associated with the existing commonly used asphalt low-temperature performance grading system, cannot guide the selection of asphalt, and the test results depend largely on the storage temperature.

[0004] The Ontario Ministry of Transportation in Canada uses the Extended Bending Beam Method LS-308 (ExBBR) to determine the true low-temperature performance grade and degree of thermally reversible aging of asphalt after accounting for thermally reversible aging. The grade loss (the difference between the continuous low-temperature grade obtained after 72 hours of low-temperature aging and the standard grade obtained after 1 hour) is used as an evaluation parameter for the degree of thermally reversible aging of asphalt at low temperatures. The grade loss must not exceed 6°C to prevent the use of asphalt sensitive to reversible aging. This method has also been adopted by the American Ashto Organization (AASHTO) as TP122-16. Compared to other methods, ExBBR offers several significant advantages, leading to its implementation in Ontario, Canada. First, it is based on existing bending beam rheological tests and can indicate the true low-temperature ambient temperature to which a particular asphalt can withstand. Second, the ExBBR grade loss metric comprehensively considers creep stiffness and creep rate and has a clear physical meaning. However, the method requires 72 hours of storage at low-temperature ambient temperature to determine the true grade temperature, a lengthy testing period that has hindered its further promotion and application. In addition, the current ExBBR method uses anhydrous ethanol to cure asphalt for 72 hours, which causes anhydrous ethanol to diffuse into the asphalt, thereby affecting the determination of asphalt properties (Mihai Marasteanu et al., published in Construction and Building Materials, 2018, 162, 80-87). Summary of the Invention

[0005] In response to the above-mentioned problems in the prior art, the present invention provides a method for quickly determining the true low-temperature grade and thermally reversible aging degree of asphalt, so as to solve the problem that the traditional AASHTO TP 122-16 and LS-308 test methods require the asphalt to be stored at a constant temperature for 72 hours before the true low-temperature grade temperature of asphalt can be obtained. The present invention adopts an externally programmed high and low temperature control box to achieve ramp cooling, and applies an oscillating thermal history during the cooling process, so that the asphalt can quickly reach a thermodynamic equilibrium state, while reducing the long-term contact between asphalt and anhydrous ethanol, thereby avoiding the diffusion of anhydrous ethanol into the asphalt and affecting the measurement results of the asphalt properties.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A method for rapidly determining the true low-temperature grade and thermally reversible aging degree of asphalt comprises the following steps:

[0008] Step 1: Heat the asphalt to a fluid state to remove thermal history and melt the crystalline components in the asphalt. Then, pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0009] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80-100°C. Keep the sample at the preset temperature for 10 minutes and then cool it down at a constant rate.

[0010] Step 3: Cool the asphalt sample from the preset temperature of the temperature control box to -20°C at a cooling rate of 3-10°C / h. During the cooling process, apply a cyclic oscillating thermal history with an amplitude of ±0.02-0.05°C every 120 seconds. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0011] Step 4: Quickly demould the asphalt and transfer it to a place with a temperature set to T HT The bending beam rheometer was placed in a constant temperature bath for 10 minutes and then tested to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0012] Step 5: Raise the temperature of the thermostat of the bending beam rheometer to the set temperature T LT , and tested after 10 minutes of constant temperature, and the creep stiffness S corresponding to loading for 60 seconds was obtained. F2 and creep rate m F2 ;

[0013] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real :

[0014] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0015] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0016] Step 7: Use the actual low temperature performance grade T of asphalt real The difference from the conventional 1h asphalt grading temperature LTPG quantifies the extent of thermally reversible aging of asphalt.

[0017] Furthermore, in step 1, the temperature of the flowing state is 170°C.

[0018] Furthermore, in step 2, the cooling medium of the programmable high and low temperature control box is compressed dry air.

[0019] Furthermore, in step 3, the cyclic oscillation thermal history adopts a thermal history with sinusoidal or triangular wave changes.

[0020] Furthermore, in step 3, the cooling rate is 3-5°C / h.

[0021] In summary, compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] 1. The method of the present invention still determines the low-temperature grade of asphalt by using a bending beam rheometer (BBR) without the need for additional low-temperature performance characterization equipment, and can be well integrated into the existing asphalt pavement low-temperature cracking control system;

[0023] 2. The present method can reduce the testing time of the existing AASHTO TP 122-16 and LS-308 test methods to less than 20 hours, while achieving the same extreme low-temperature classification temperature and classification loss indicators as AASHTO TP 122-16 and LS-308. This significantly shortens the testing time while maintaining test accuracy, accelerating the development of new thermally resistant and reversibly aging asphalt materials and reducing construction delays caused by lengthy quality testing.

[0024] 3. The method of the present invention can simultaneously apply thermal history to a large number of different asphalts, greatly improving testing efficiency. Specifically, a large number of cast asphalt BBR beam specimens can be placed in a designated external programmable high and low temperature control chamber at one time. The cyclic oscillating thermal history applied by the programmable high and low temperature control chamber can accelerate the asphalt batch to reach equilibrium state.

[0025] 4. The method of the present invention can avoid the property changes caused by immersing asphalt in anhydrous ethanol for 72 hours (such as oil analysis in asphalt into anhydrous ethanol or chemical reaction between asphalt and anhydrous ethanol) by using an external programmable high and low temperature control box;

[0026] 5. The method for grading the actual low-temperature performance of asphalt and quantifying the degree of thermally reversible aging of asphalt proposed in the present invention has simple operation and high testing efficiency, and has high promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a thermal wave diagram of the sinusoidal cyclic oscillation heat history applied to the asphalt sample in Example 1 of the present invention;

[0028] Figure 2 This is a thermal wave diagram of the triangular wave cyclic oscillation thermal history applied to the asphalt sample in Example 4 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with various embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0030] The following examples of the present invention use a certain No. 110 asphalt as a test material to further illustrate the present invention.

[0031] Example 1

[0032] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0033] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0034] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0035] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0036] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0037] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0038] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula sand creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0039] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0040] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0041] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0042] Example 2

[0043] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0044] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0045] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0046] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. After cooling to -20°C, keep the temperature constant for 10 minutes.

[0047] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0048] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0049] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0050] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0051] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0052] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0053] Example 3

[0054] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0055] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0056] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0057] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 10°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.05°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0058] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0059] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0060] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0061] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0062] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0063] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0064] Example 4

[0065] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 2 As shown, the specific steps include:

[0066] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0067] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0068] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. Apply a triangular wave cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0069] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0070] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0071] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0072] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0073] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0074] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0075] Example 5

[0076] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0077] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0078] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 30°C. Keep the sample at 30°C for 10 minutes and then cool it down at a constant rate.

[0079] Step 3: Cool the asphalt sample from 30°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0080] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0081] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0082] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0083] T s =T HT -(T LT -T HT )×[(logS F2-log300) / (logS F1 -logS F2 )]-10℃

[0084] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0085] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0086] Example 6

[0087] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0088] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0089] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0090] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.01°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0091] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0092] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0093] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0094] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0095] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0096] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0097] Example 7

[0098] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0099] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0100] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0101] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.05°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0102] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0103] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0104] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0105] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0106] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0107] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0108] Example 8

[0109] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0110] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0111] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0112] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.06°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0113] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0114] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0115] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0116] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0117] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0118] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0119] Example 9

[0120] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0121] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0122] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 100°C. Keep the sample at 100°C for 10 minutes and then cool it down at a constant rate.

[0123] Step 3: Cool the asphalt sample from 100°C to -20°C at a cooling rate of 5°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0124] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0125] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0126] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0127] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0128] T m =THT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0129] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0130] Example 10

[0131] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0132] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0133] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0134] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 3°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds during the cooling process. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0135] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0136] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0137] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt Treal .

[0138] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0139] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0140] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0141] Example 11

[0142] This embodiment uses the above-mentioned asphalt for testing. The thermal history of the asphalt is as follows: Figure 1 As shown, the specific steps include:

[0143] Step 1: Heat 100g of asphalt to a flowing state of 170℃ to remove the thermal history and melt the crystalline components in the asphalt. Then pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling.

[0144] Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box with a preset temperature of 80°C. Keep the sample at 80°C for 10 minutes and then cool it down at a constant rate.

[0145] Step 3: Cool the asphalt sample from 80°C to -20°C at a cooling rate of 12°C / h. Apply a sinusoidal cyclic oscillation thermal history with an amplitude of ±0.02°C every 120 seconds. After cooling to -20°C, hold the sample at this temperature for 10 minutes.

[0146] Step 4: Rapidly demould the asphalt and transfer it to a thermostatic bath of a bending beam rheometer at -18°C for 10 minutes before testing to obtain the creep stiffness S corresponding to 60 seconds of loading. F1 and creep rate m F1 ;

[0147] Step 5: Place the asphalt sample in the thermostatic bath of the bending beam rheometer, raise the temperature to -12°C, and perform a three-point bending loading test after 10 minutes of constant temperature to obtain the creep stiffness S corresponding to 60 seconds of loading. F2 and creep rate m F2 ;

[0148] Step 6: Calculate the creep stiffness limit cracking temperature T according to the following formula s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real .

[0149] T s =T HT -(T LT -T HT )×[(logS F2 -log300) / (logS F1 -logS F2 )]-10℃

[0150] T m =T HT -(T LT -T HT )×[(m F2 -0.3) / (m F1 -m F2 )]-10℃

[0151] Step 7: Use the actual low temperature performance grade T of asphalt real The difference between the conventional 1h asphalt grading temperature LTPG (T real -LTPG) quantifies the extent of thermally reversible aging of asphalt.

[0152] The test results of a certain 110# unmodified asphalt obtained using AASHTO TP122-16 or LS-308 are shown in Table 1.

[0153] Table 1 Extended bending beam rheological test results of a 110# unmodified asphalt

[0154]

[0155] Note: According to the asphalt specification of Ontario, Canada, a difference of grading temperature or grading loss within 3°C can be considered as no significant change.

[0156] The actual low-temperature performance grading temperature and grading loss of the same 110# unmodified asphalt can be obtained by using Examples 1 to 11, as shown in Table 2.

[0157] Table 2 110# unmodified asphalt

[0158]

[0159]

[0160] Combined with the asphalt low-temperature performance grading test results after cyclic oscillation cooling thermal history treatment in the embodiment and the ExBBR results of AASHTO TP 122-16 and LS-308, the cyclic oscillation thermal history treatment proposed in the present invention can accelerate the asphalt to reach an equilibrium state, thereby obtaining the true low-temperature performance grading and grading loss parameters of asphalt with accuracy comparable to the AASHTO 122-16 and LS-308 standards. At the same time, the specific parameters of this method can shorten the original 72-hour constant temperature test time to less than 20 hours, greatly improving the test efficiency. The preset temperature, cooling rate, and amplitude of the thermal history of the programmable high and low temperature control box all affect the experimental results, while the normal waveform of the thermal history has less impact.

[0161] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A method for rapidly determining the true low-temperature grade and thermally reversible aging degree of asphalt, characterized in that: The steps include: Step 1: Heat the asphalt to a fluid state to remove thermal history and melt the crystalline components in the asphalt. Then, pour the asphalt into an aluminum bending beam rheometer mold. After cooling for 30 minutes, use a hot knife to cut off the asphalt sample that is higher than the top of the mold after cooling. Step 2: Place the test mold filled with asphalt in a programmable high and low temperature control box. The cooling medium of the programmable high and low temperature control box is compressed dry air. The preset temperature of the temperature control box is 80-100°C. The sample is kept at the preset temperature of the temperature control box for 10 minutes and then cooled at a constant rate. Step 3: Cool the asphalt sample from the preset temperature of the temperature control box to -20°C at a cooling rate of 3-5°C / h. During the cooling process, apply a cyclic oscillating thermal history with an amplitude of ±0.02-0.05°C every 120 seconds. After cooling to -20°C, maintain the temperature at this temperature for 10 minutes. The cyclic oscillating thermal history uses a thermal history with a sine wave or triangular wave change. Step 4: Quickly demould the asphalt and transfer it to a place where the temperature is set T HT The bending beam rheometer was placed in a constant temperature bath for 10 minutes and then tested to obtain the creep stiffness corresponding to 60 seconds of loading. S F1 and creep rate m F1 ; Step 5: Raise the temperature of the thermostat of the bending beam rheometer to the set temperature T LT , and tested after 10 minutes of constant temperature, and the creep stiffness corresponding to 60 seconds of loading was obtained. S F2 and creep rate m F2 ; Step 6: Calculate the creep stiffness limit cracking temperature according to the following formula T s and creep rate limiting cracking temperature T m The maximum value of the two is the actual low temperature performance grading temperature of asphalt T real : ； Step 7: Apply asphalt real low temperature performance grading T real The difference from the conventional 1h asphalt grading temperature LTPG quantifies the degree of thermally reversible aging of asphalt.

2. The method for rapidly determining the true low-temperature grade and thermally reversible aging degree of asphalt according to claim 1, characterized in that: In step 1, the temperature of the flowing state is 170°C.

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