Method and electronic device for evaluating low-temperature crack resistance of asphalt considering physical hardening

Abstract

The present application relates to a kind of asphalt low temperature crack resistance performance evaluation method and electronic equipment considering physical hardening, prepare asphalt sample by silica gel mould and 4mm DSR, temperature calibration is carried out to asphalt sample, obtain temperature equilibrium time;Based on the compliance value, the complex modulus and phase angle of asphalt sample are corrected;Determine the best indoor time detection of physical hardening under asphalt low temperature environment, after asphalt sample hardens, carry out frequency and strain scanning test to asphalt sample under different low temperature, determine the importance of physical hardening on asphalt low temperature rheological property according to frequency scanning result, obtain the influence of physical hardening on asphalt low temperature rheology under nonlinear strain level in asphalt fracture test process according to strain scanning result, realize asphalt low temperature crack resistance performance evaluation.Compared with prior art, the method needs less consumables to evaluate asphalt low temperature crack resistance performance, and is efficient and accurate.

Description

Technical Field

[0001] This invention relates to the field of low-temperature crack resistance evaluation technology for asphalt, and in particular to a method and electronic device for evaluating the low-temperature crack resistance of asphalt that takes into account physical hardening. Background Technology

[0002] In cold climates, low-temperature cracking of asphalt pavements is influenced by multiple factors, including materials, structure, and environment. Among the material factors, the low-temperature rheological properties of the asphalt binder are the primary one. While the BBR test is a commonly used evaluation method, its low-temperature isothermal storage time is only 1 hour, failing to adequately consider unloaded cracking caused by long-term low-temperature hardening of asphalt. Furthermore, it only characterizes deformation capacity and stress relaxation performance using stiffness modulus S and creep rate m, respectively. However, the low-temperature performance of asphalt is affected by both deformation capacity and stress relaxation. Therefore, evaluating the low-temperature performance of asphalt solely based on S or m values ​​is incomplete. Recent research indicates that the ExBBR test, which considers the physical hardening of asphalt binders below room temperature, calculates the ultimate low-temperature performance grade (LTPG) corresponding to different hardening times by setting three curing periods at -18℃: 1 hour, 24 hours, and 72 hours. By calculating the differences between the three LTPGs and the low-temperature grade loss (GL), a more accurate correlation between the low-temperature rheological properties of the binder and the crack resistance of the pavement can be established.

[0003] To address the issues of high material consumption and limited testing of recycled materials in BBR (Bipolar Transformer) tests, DSR (Dynamic Shear Rheometer) technology has been developed for low-temperature measurements. The 8mm parallel plate DSR (8mm DSR, where DSR stands for Dynamic Shear Rheometer) suffers from significant compliance errors in the absolute value of the dynamic modulus below 5℃, making it difficult to test. However, the 4mm parallel plate and 1.75mm gap (4mm DSR) setup, along with data correction, solves this instrument error problem, requiring only 150mg of material (far less than the 15g required for BBR). Currently, within the temperature range of -40℃ to 5℃, the low-temperature rheological properties of asphalt can be characterized using 4mm DSR, and the test results show a strong correlation with those obtained from BBR tests. Furthermore, most studies on the physical hardening characterization of asphalt based on this technology focus on constructing the master curve at a specific low temperature, without considering the influence of low-temperature physical hardening. However, low-temperature physical hardening of asphalt can lead to unevenness in the master curve construction, hindering the determination of the shift factor.

[0004] A search revealed Chinese invention patent application publication number CN117272580 A, which discloses a method for predicting the low-temperature performance of asphalt using DSR based on frequency and time domain data conversion. The method includes the following steps: pouring asphalt samples; firstly, conducting temperature and frequency scanning tests using a dynamic shear rheometer (DSR) to obtain the dynamic shear modulus G* and phase angle δ at different temperatures and frequencies; then, fitting the master curve of the test data and extending the master curves of G* and δ using the time-temperature equivalence principle to obtain the corresponding low-temperature frequencies' G* and δ; subsequently, converting the asphalt modulus G*(ω) into a compliance component J'(ω), and then converting the frequency domain data J(ω) into time domain data J(t) using the frequency-time domain conversion equation J(t)=J'(ω)ω=2 / πt; finally, calculating the creep stiffness S(t) and its rate of change m based on J(t) to evaluate the low-temperature crack resistance of asphalt. Furthermore, a set of calibration factors is introduced to calibrate the prediction results, thereby obtaining more accurate low-temperature asphalt performance evaluation indicators. The existing patent application has the problem that it only uses creep stiffness S(t) and its rate of change m to evaluate the performance of low-temperature asphalt, without considering the influence of physical hardening, and therefore the evaluation of the crack resistance of low-temperature asphalt is inaccurate.

[0005] How to evaluate the low-temperature crack resistance of asphalt considering physical hardening has become a technical problem that needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for evaluating the low-temperature crack resistance of asphalt that considers physical hardening, so as to solve the problems of large asphalt consumption, long testing time and limited hardening temperature in the traditional bending beam rheological test characterization of the low-temperature crack resistance of asphalt that considers physical hardening.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] According to one aspect of the present invention, a method for evaluating the low-temperature crack resistance of asphalt considering physical hardening is provided, the method comprising the following steps:

[0009] Asphalt samples were prepared using a silicone mold and a 4mm DSR. The temperature of the asphalt samples was calibrated, and the time required for the temperature of the asphalt samples to reach equilibrium was determined and recorded as the temperature equilibrium time.

[0010] Instrumental compliance measurement was performed on a 4 mm DSR, and the complex modulus and phase angle of the asphalt sample were corrected based on the measured compliance value.

[0011] Based on the curves of the evolution of complex modulus and phase angle with hardening time after correction by 4mm DSR, numerical algorithm is used to determine the optimal indoor time to characterize the physical hardening of asphalt under low temperature conditions.

[0012] Based on the temperature equilibrium time and the optimal indoor time for physical hardening, asphalt samples were stored at a constant low temperature until they reached physical hardening. Then, frequency and strain scanning tests were performed on the asphalt samples at different low temperatures to evaluate the low-temperature crack resistance of asphalt.

[0013] Preferably, the process of calibrating the temperature of the asphalt sample includes:

[0014] Select a variety of typical low-temperature environments, use a real-time temperature monitoring instrument to detect the temperature of the asphalt sample in real time, and insert and fix the thermocouple in the middle position of the asphalt sample between the upper and lower plates of the 4mm DSR.

[0015] The temperature was lowered to a constant low temperature, and the temperature of the asphalt sample was recorded according to the data displayed on the real-time temperature monitoring instrument. The time required for the temperature of the asphalt sample to reach equilibrium was determined based on the temperature fluctuation.

[0016] Preferably, the process of correcting the complex modulus and phase angle of the asphalt sample includes:

[0017] Based on the compliance values ​​of the 4mm DSR instrument, additional compliance corrections were performed on the complex modulus and phase angle of the asphalt samples. The complex modulus includes the shear storage modulus and the shear loss modulus, specifically:

[0018]

[0019] In the formula, (G*) m ′ and (G*) c ′ represents the shear storage modulus before and after compliance correction, respectively; (G*)m″ and (G*)m″. c "These are the shear loss moduli before and after compliance correction, respectively; δ" c The phase angle after compliance correction; J E The compliance value measured by a 4mm DSR instrument; k g Let be a geometric constant, and its formula is:

[0020]

[0021] In the formula, h is the gap between the upper and lower plates of the 4mm DSR; R is the radius of the 4mm DSR parallel plate.

[0022] Preferably, the process of obtaining the evolution curves of the complex modulus and phase angle with hardening time includes:

[0023] Various unaged waxy asphalt binders were selected and stored at constant temperature for three days under different low-temperature conditions. They were then continuously loaded with constant frequency and strain, and the normal force was set to zero. Based on a 4mm DSR, the evolution curves of complex modulus and phase angle with hardening time were obtained. The optimal indoor time for characterizing the low-temperature physical hardening of asphalt was then fitted using a numerical algorithm of a typical logarithmic function equation.

[0024] Preferably, the process of evaluating the low-temperature crack resistance of asphalt includes:

[0025] The importance of physical hardening to the low-temperature rheological properties of asphalt was determined based on the frequency scanning results.

[0026] The effect of physical hardening on the low-temperature rheology of asphalt under nonlinear strain levels was obtained based on the strain scanning results.

[0027] More preferably, the process of determining the importance of physical hardening to the low-temperature rheological properties of asphalt based on the frequency scanning results includes: performing frequency scanning tests on all asphalt samples at different low-temperature temperatures, taking into account the time before and after physical hardening; comparing the differences in complex modulus caused by different hardening times; and determining the influence of physical hardening on the low-temperature rheological properties of asphalt by comparing the changes in complex modulus caused by asphalt physical hardening and penetration grade differences.

[0028] More preferably, the process of obtaining the influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain level includes: conducting scanning tests on all asphalt samples at a constant frequency at different low-temperature temperatures, taking into account the linear increase in strain before and after physical hardening, obtaining the stress-strain curves of non-waxy and waxy asphalt after low-temperature isothermal storage, and comparing them with the stress-strain curves of those not subjected to isothermal storage, so as to reflect the influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain level from the asphalt fracture test process.

[0029] Preferably, the method includes conducting an adhesion test on the asphalt sample, and after the adhesion test meets the requirements, using a numerical algorithm to determine the optimal indoor time for characterizing the physical hardening of asphalt under low-temperature conditions.

[0030] Preferably, the process of testing the adhesion of asphalt samples includes: performing strain scanning tests on asphalt samples within a strain range at a constant frequency and different typical low temperature ranges, and obtaining the adhesion effect between the asphalt samples and the upper and lower plates of the 4mm DSR by observing the fracture images of the asphalt samples after the strain scanning test.

[0031] According to another aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the program to implement the method described thereon.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) This invention is based on a method for evaluating the low-temperature crack resistance of asphalt using a 4mm DSR. It calculates the temperature equilibrium time and the optimal indoor time for physical hardening of asphalt under different low-temperature environments. Considering the influence of physical hardening, it conducts frequency and strain scanning tests on the low-temperature isothermal conditioning process, reducing the test time from 72 hours and 20 minutes to 4 hours and 20 minutes and the asphalt material consumption from 15g to 150mg. This highlights the differences in physical hardening behavior of asphalt and the effect of physical hardening on the low-temperature crack resistance of asphalt, achieving the goal of evaluating the low-temperature crack resistance of asphalt considering physical hardening. This provides theoretical and methodological support for establishing a more comprehensive evaluation method for the low-temperature performance of asphalt pavement.

[0034] 2) Before frequency and strain scanning tests, this invention obtains the temperature equilibrium time of asphalt under different low-temperature environments through temperature calibration, and obtains the optimal indoor time for physical hardening through strain scanning tests. This shortens the time and improves the evaluation efficiency for the low-temperature crack resistance performance of asphalt considering physical hardening.

[0035] 3) The present invention corrects the complex modulus and phase angle of asphalt samples based on the compliance value of the 4mm DSR instrument. This is a key step in the evaluation of the low-temperature crack resistance of asphalt and helps to improve the accuracy of the evaluation of the low-temperature crack resistance of asphalt.

[0036] 4) This invention considers physical hardening, and the frequency scanning results determine the importance of physical hardening to the low-temperature rheological properties of asphalt; the strain scanning results obtain the influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain levels during the asphalt fracture test. Compared with the BBR test, which does not consider physical hardening to evaluate the low-temperature performance of asphalt, this invention is more comprehensive and accurate. Attached Figure Description

[0037] Figure 1 This is a schematic diagram illustrating the principle of the low-temperature crack resistance evaluation method for asphalt in this invention.

[0038] Figure 2 The real-time temperature change graph of a 4mm DSR asphalt sample is provided for the low-temperature crack resistance evaluation method of asphalt in this invention.

[0039] Figure 3 Linear fitting curve of angular displacement and torque of 4mm DSR parallel plate provided for the low-temperature crack resistance evaluation method of asphalt in this invention;

[0040] Figure 4 The graph shows the evolution of the complex modulus of unaged waxy asphalt within a 72-hour hardening time, as provided by the low-temperature crack resistance evaluation method for asphalt in this invention.

[0041] Figure 5This invention provides the difference in penetration grade at different frequencies and the rate of change in complex modulus caused by physical hardening in the evaluation method for low-temperature crack resistance of asphalt.

[0042] Figure 6 The stress-strain relationship curves of four types of asphalt at 10℃ and hardening times of 0 and 4 hours are provided for the low-temperature crack resistance evaluation method of asphalt in this invention.

[0043] Figure 7 This is a flowchart illustrating the method for evaluating the low-temperature crack resistance of asphalt in the invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment relates to a method for evaluating the low-temperature crack resistance of asphalt considering physical hardening, where low temperature refers to -20℃ to 10℃.

[0047] like Figure 1 and Figure 7 The method includes the following steps:

[0048] S1. Prepare and process asphalt samples using a silicone mold and a 4mm DSR. Then, calibrate the temperature of the asphalt samples and determine the time required for the temperature of the asphalt samples to reach equilibrium based on the temperature fluctuations. This time is recorded as the temperature equilibrium time.

[0049] S2. Perform instrument compliance measurement on the 4mm DSR to obtain the measurement result of the relationship between angular displacement and torque, i.e. compliance value. Then, based on the measured compliance value, correct the complex modulus and phase angle of the asphalt sample.

[0050] S3. Under constant frequency and different typical low temperature ranges, strain scanning tests were performed on asphalt samples to detect their adhesion, specifically the adhesion effect between the asphalt sample and the upper and lower plates of a 4mm DSR. If the adhesion test meets the requirements, the effectiveness of the 4mm DSR method for asphalt samples is demonstrated.

[0051] S4. Different unaged waxy asphalt binders were selected and stored in a constant low temperature environment. Based on the 4mm DSR instrument, the curves of the evolution of the corrected complex modulus and phase angle with hardening time were exported. Numerical algorithms were used to determine the optimal indoor time to characterize the low-temperature physical hardening of asphalt.

[0052] S5. After the asphalt samples are stored at a constant low temperature for a temperature equilibrium time and the optimal indoor time for physical hardening, physical hardening is achieved. Then, frequency and strain scanning tests considering physical hardening are performed on the asphalt samples at different low temperatures. The importance of physical hardening to the low-temperature rheological properties of asphalt is determined based on the frequency scanning results. The influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain level is obtained based on the strain scanning, thereby realizing the evaluation of the low-temperature crack resistance of asphalt.

[0053] The process of S1 includes:

[0054] S11. Asphalt samples are prepared and processed using a silicone mold and a 4mm DSR. The detailed steps include: making a silicone mold with a diameter of 4mm and a depth of 2mm; heating the lower plate of the 4mm DSR to 60℃ to ensure good adhesion between the sample and the upper and lower plates of the 4mm DSR; adjusting the distance between the upper and lower plates of the 4mm DSR to 1.800mm, while lowering the DSR temperature to 20℃ to allow the asphalt sample to expand outwards, and lifting the DSR PTD200 cover; trimming the asphalt sample with a hot scraper; after the asphalt sample is trimmed, pressing down the DSR PTD 200 cover and adjusting the DSR gap to 1.750mm.

[0055] S12, temperature calibration of the asphalt sample. Detailed steps include: selecting four typical low-temperature environments (-20℃, -10℃, 0℃, and 10℃); using a real-time temperature monitor to detect the asphalt sample temperature in real time; inserting and fixing the thermocouple attached to the real-time temperature monitor between the upper and lower plates of the 4mm DSR; finally, lowering the temperature to a constant low temperature, recording the asphalt sample temperature according to the data displayed on the real-time temperature monitor, and determining the time required for the asphalt sample temperature to reach equilibrium based on temperature fluctuations. The results are as follows: Figure 2 As shown, the asphalt samples reached equilibrium within 20 minutes under four typical low-temperature environments.

[0056] The process of S2 includes:

[0057] S21, The detailed steps for measuring the compliance of a 4mm DSR include: applying a strong adhesive cyanoacrylate to the parallel center position between the upper and lower plates of the 4mm DSR to reduce the gap between them and ensure a uniform thin layer of adhesive, thus guaranteeing strong adhesion; allowing the adhesive to cure between the upper and lower plates for 3 hours; adjusting the gap between the upper and lower plates in real time during curing to maintain zero normal force; and performing a stress scanning test after curing to measure the angular displacement generated by the 4mm DSR within a certain torque range, thereby obtaining the relationship between angular displacement and torque, i.e., the compliance value. The results are as follows. Figure 3 As shown.

[0058] S22, based on the measured flexibility values, the asphalt samples are corrected for complex modulus (both shear storage modulus and shear loss modulus are complex moduli) and phase angle. Detailed steps include:

[0059] Based on the compliance values ​​of the 4mm DSR instrument, additional compliance corrections were performed on the shear storage modulus, shear loss modulus, and phase angle of the asphalt samples, obtained through the following method:

[0060]

[0061] In the formula, (G*) m ′ and (G*) c ′ represents the shear storage modulus before and after compliance correction, respectively; (G*)m″ and (G*)m″. c "These are the shear loss moduli before and after compliance correction, respectively; δ" c The phase angle after compliance correction; J E The compliance value measured by a 4mm DSR instrument; k g Let be a geometric constant, and its formula is:

[0062]

[0063] In the formula, h is the gap between the upper and lower plates of the 4mm DSR; R is the radius of the 4mm DSR parallel plate; and π is pi.

[0064] In S2, the instrument compliance correction method uses the compliance values ​​of a 4mm DSR instrument to correct the complex modulus and phase angle.

[0065] In S3, the steps for testing the adhesion of asphalt samples include: performing strain scanning tests on asphalt samples within a strain range of 0.1% to 30% at a constant frequency of 10 Hz and different typical low temperature ranges, observing the fractured physical image of the asphalt sample after the test, and obtaining the adhesion of the asphalt sample.

[0066] In S4, the steps for determining the optimal indoor hardening time of asphalt samples using numerical algorithms include: selecting three types of unaged waxy asphalt binders, storing them at different low temperatures for 3 days, continuously loading them at a constant frequency of 0.05Hz and a strain of 0.01%, and setting the normal force to zero; and obtaining the evolution curves of complex modulus and phase angle with hardening time based on the 4mm DSR method (e.g., ...). Figure 4 The optimal indoor time for characterizing the low-temperature physical hardening of asphalt was determined using a numerical algorithm based on a typical function equation, where the typical function is the typical logarithmic function. Figure 4 It can be seen that, under the 4mm DSR method, asphalt samples reached physical hardening equilibrium (complex modulus change rate ≤5%) 4 hours after temperature equilibrium under different low-temperature conditions, which is much shorter than the evaluation time of 72 hours for low-temperature physical hardening in the BBR test.

[0067] The S5 process includes:

[0068] S51, frequency scanning tests were conducted on asphalt samples at different low temperatures, and the importance of physical hardening to the low-temperature rheological properties of asphalt was determined based on the test results. The detailed steps included: conducting frequency scanning tests on all asphalt samples at different temperatures considering physical hardening before and after, comparing the differences in complex modulus caused by different hardening times, and determining the influence of physical hardening on the low-temperature rheological properties of asphalt by comparing the changes in complex modulus caused by differences in asphalt physical hardening and penetration grade, respectively; the determination of the asphalt penetration grade was based on the European penetration grade standard EN 12591:2009.

[0069] S52, strain scanning tests were conducted on asphalt samples at different low temperatures. Based on the test results, the influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain levels during the asphalt fracture test was determined. The detailed steps included: conducting a linearly increasing strain scanning test at a constant frequency to obtain the stress-strain curves of non-waxy and waxy asphalt after low-temperature isothermal storage, and comparing them with the stress-strain curves of asphalt without isothermal storage; the influence of physical hardening on the low-temperature rheology of asphalt under nonlinear strain levels was demonstrated from the asphalt fracture test process.

[0070] Example 2

[0071] This embodiment also relates to the application of a method for evaluating the low-temperature crack resistance of asphalt that takes into account physical hardening. This evaluation method is used to evaluate the low-temperature performance of four existing types of asphalt:

[0072] Three waxy asphalt binders (asphalt samples B, C, and D) were obtained, and their complex modulus changes after 4 hours of hardening were compared with those caused by using asphalt with different penetration grades. The results are as follows: Figure 5 As shown, at most temperatures, the change in complex modulus caused by 4 hours of isothermal storage can reach nearly 50% of the change in complex modulus caused by the differences in the three penetration grades of asphalt A (non-waxy asphalt). Therefore, physical hardening is an important factor to consider when selecting asphalt binders and evaluating the low-temperature rheological properties of asphalt. Ignoring this factor in low-temperature rheological tests may lead to an overestimation of the low-temperature performance grade of asphalt binders.

[0073] This embodiment demonstrates the influence of physical hardening on the low-temperature rheological properties of asphalt from another perspective, such as the fracture properties of asphalt. Figure 6 As shown, the 4mm DSR method effectively displays the stress-strain curves of asphalt samples at 10℃. The peak effective shear stresses of non-waxed asphalt A before and after 4 hours of hardening are 1.638 MPa and 1.661 MPa, respectively, a difference of 1.41%. For waxed asphalts B, C, and D, the peak effective shear stresses before isothermal hardening are 2.151 MPa, 3.244 MPa, and 1.446 MPa, respectively. After 4 hours of hardening, the peak stresses increase to 2.627 MPa, 3.914 MPa, and 1.598 MPa, representing increases of 22.13%, 20.65%, and 10.51% compared to before hardening. Therefore, compared to non-waxed asphalt, the isothermal hardening process significantly increases the internal stress of waxed asphalt, which is attributed to the physical hardening of waxed asphalt during 10℃ isothermal storage. Furthermore, from an engineering performance perspective, the significant stress generated within the asphalt during physical hardening will impair the low-temperature crack resistance of asphalt pavements.

[0074] Therefore, the above-mentioned rapid evaluation method for the low-temperature crack resistance of asphalt considering physical hardening solves the problems of large asphalt consumption, long testing time, and limited hardening temperature in the traditional bending beam rheological test characterization of the low-temperature crack resistance of asphalt considering physical hardening.

[0075] Example 3

[0076] The electronic device of this invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0077] Multiple components in the device are connected to the I / O interface, including: input units such as keyboards and mice; output units such as various types of displays and speakers; storage units such as disks and optical discs; and communication units such as network interface cards (NICs), modems, and wireless transceivers. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0078] The processing unit performs the various methods and processes described above. For example, in some embodiments, the methods may be implemented as computer software programs tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the methods described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute the methods by any other suitable means (e.g., by means of firmware).

[0079] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0080] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0081] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory, optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for evaluating the low-temperature crack resistance of asphalt considering physical hardening, characterized in that, The method includes the following steps: Asphalt samples were prepared using a silicone mold and a 4mm DSR. The temperature of the asphalt samples was calibrated, and the time required for the temperature of the asphalt samples to reach equilibrium was determined and recorded as the temperature equilibrium time. Instrumental compliance measurement was performed on a 4 mm DSR, and the complex modulus and phase angle of the asphalt sample were corrected based on the measured compliance value. Based on the curves of the evolution of complex modulus and phase angle with hardening time after correction by 4mm DSR, numerical algorithm is used to determine the optimal indoor time to characterize the physical hardening of asphalt under low temperature conditions. Based on the temperature equilibrium time and the optimal indoor time for physical hardening, after the asphalt samples are stored at a constant low temperature to achieve physical hardening, frequency and strain scanning tests are performed on the asphalt samples at different low temperature temperatures to evaluate the low temperature crack resistance of asphalt. The process for evaluating the low-temperature crack resistance of asphalt includes: The importance of physical hardening to the low-temperature rheological properties of asphalt was determined based on the frequency scanning results. The low-temperature crack resistance of asphalt considering physical hardening factors under nonlinear strain levels is obtained based on strain scanning results. The process of determining the importance of physical hardening to the low-temperature rheological properties of asphalt based on frequency scanning results includes: performing frequency scanning tests on all asphalt samples at different low-temperature temperatures, considering the difference before and after physical hardening; comparing the differences in complex modulus caused by different hardening times; and determining the influence of physical hardening on the low-temperature rheological properties of asphalt by comparing the changes in complex modulus caused by asphalt physical hardening and penetration grade differences. The process of obtaining the effect of physical hardening on the low-temperature rheology of asphalt under nonlinear strain level includes: conducting scanning tests on all asphalt samples at a constant frequency at different low-temperature temperatures, taking into account the linear increase in strain before and after physical hardening, obtaining the stress-strain curves of non-waxy and waxy asphalt after low-temperature isothermal storage, and comparing them with the stress-strain curves of those not subjected to isothermal storage, so as to reflect the effect of physical hardening on the low-temperature crack resistance of asphalt from the asphalt fracture test process.

2. The method for evaluating the low-temperature crack resistance of asphalt considering physical hardening according to claim 1, characterized in that, The process of calibrating the temperature of the asphalt sample includes: Select a variety of typical low-temperature environments, use a real-time temperature monitoring instrument to detect the temperature of the asphalt sample in real time, and insert and fix the thermocouple in the middle position of the asphalt sample between the upper and lower plates of the 4mm DSR. The temperature was lowered to a constant low temperature, and the temperature of the asphalt sample was recorded according to the data displayed on the real-time temperature monitoring instrument. The time required for the temperature of the asphalt sample to reach equilibrium was determined based on the temperature fluctuation.

3. The method for evaluating the low-temperature crack resistance of asphalt considering physical hardening according to claim 1, characterized in that, The process of correcting the complex modulus and phase angle of the asphalt sample includes: Based on the compliance values ​​of the 4mm DSR instrument, additional compliance corrections were performed on the complex modulus and phase angle of the asphalt samples. The complex modulus includes the shear storage modulus and the shear loss modulus, specifically: ； ； ； In the formula, (G ) m ′ and (G ) c ′ represents the shear storage modulus before and after compliance correction, respectively; (G )m′′ and (G ) c ′′ represent the shear loss modulus before and after compliance correction, respectively; δ c The phase angle after compliance correction; J E The compliance value measured by a 4mm DSR instrument; k g Let be a geometric constant, and its formula is: ； In the formula, h is the gap between the upper and lower plates of the 4mm DSR; R is the radius of the 4mm DSR parallel plate.

4. The method for evaluating the low-temperature crack resistance of asphalt considering physical hardening according to claim 1, characterized in that, The process of obtaining the curves showing the evolution of the complex modulus and phase angle over hardening time includes: Various unaged waxy asphalt binders were selected and stored at constant temperature for three days under different low-temperature conditions. They were then continuously loaded with constant frequency and strain, and the normal force was set to zero. Based on a 4mm DSR, the evolution curves of complex modulus and phase angle with hardening time were obtained. The optimal indoor time for characterizing the low-temperature physical hardening of asphalt was then fitted using a numerical algorithm of a typical logarithmic function equation.

5. The method for evaluating the low-temperature crack resistance of asphalt considering physical hardening according to claim 1, characterized in that, The method involves conducting adhesion tests on asphalt samples, and then using numerical algorithms to determine the optimal indoor time for characterizing the physical hardening of asphalt under low-temperature conditions once the adhesion test meets the requirements.

6. The method for evaluating the low-temperature crack resistance of asphalt considering physical hardening according to claim 1, characterized in that, The process of testing the adhesion of asphalt samples includes: performing strain scanning tests on asphalt samples within a strain range at a constant frequency and different typical low temperature ranges; and obtaining the adhesion effect between the asphalt samples and the upper and lower plates of the 4mm DSR by observing the fracture images of the asphalt samples after the strain scanning test.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1 to 6.

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