Method for determining reaction degree of rubber asphalt and application thereof in judging aging rubber modified asphalt recycling time

Abstract

The application discloses a method for judging the reaction degree of rubber and asphalt to determine the recycling time of aged rubber modified asphalt and application thereof, and comprises the following steps: S1, obtaining a rubber modified asphalt sample and a matrix asphalt homologous to the rubber modified asphalt; the rubber modified asphalt sample and the matrix asphalt both have multiple aging degrees; S2, performing phase separation on the rubber modified asphalt sample in each aging state; S3, performing rheological property tests on the rubber modified asphalt, the asphalt phase and the matrix asphalt under preset temperature conditions of high temperature, medium temperature and low temperature respectively; S4, respectively calculating the particle effect value PE and the interaction effect value IE of each aging state in different temperature domains; and S5, dividing the aging process of the rubber modified asphalt into three stages to evaluate the reaction degree of rubber and asphalt, and determining the recycling time based on the divided aging stages. Thus, the technical problems that the reaction degree of rubber and asphalt cannot be quantitatively evaluated and the recycling time lacks scientific basis in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a method and application for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of reaction of rubber asphalt. Background Technology

[0002] Rubber-modified asphalt is an important environmentally sustainable technology for realizing the resource utilization of waste tires and improving road durability. Essentially, it is a two-phase composite system composed of a rubber phase dispersed in an asphalt phase. Throughout the preparation, service, and aging processes of this system, there are always two levels of interaction between rubber and asphalt. Firstly, there are changes in the physical state of the rubber particles themselves, including elastic filling, volume swelling, and subsequent degradation shrinkage. Secondly, there are changes in the intrinsic properties of the asphalt phase caused by material exchange and chemical reactions between rubber and asphalt. These two interactions are coupled and superimposed, and their combined result is the degree of rubber-asphalt reaction. This indicator reflects how much of the rubber particles have reacted and the depth of the rubber-asphalt interaction. Accurately evaluating the degree of rubber-asphalt reaction is a crucial prerequisite for determining the optimal time for regenerating aged rubber-modified asphalt.

[0003] However, currently used evaluation methods in this field cannot effectively quantify this degree of reaction. On the one hand, macroscopic rheological tests (such as overall rutting factor, fatigue life, etc.), conventional physical indicators (such as penetration, viscosity, softening point, etc.), and infrared spectroscopy all treat rubber-modified asphalt as a homogeneous single material, only reflecting the overall aging response of the composite system. They cannot separate the independent contributions of changes in the physical state of rubber and the chemical interaction between rubber and asphalt, and therefore cannot quantitatively evaluate the degree of rubber-asphalt reaction. On the other hand, although existing phase separation techniques (such as solvent extraction and mesh screen percolation) can achieve the physical separation of the rubber phase and the asphalt phase, most related studies stop at analyzing the chemical composition or microstructure of the separated components. They have not yet conducted further system rheological tests covering the service temperature range on the separated components, and there is a lack of a unified analytical framework that quantitatively correlates changes in component properties with the degree of rubber-asphalt reaction.

[0004] The fundamental flaw of the aforementioned existing technologies lies in the fact that they consistently treat all test results for rubber-modified asphalt as a convolutional output of particle physical effects and chemical interaction effects, with the two completely entangled and inextricably decoupled in the signal. The technical root of this flaw lies in the long-standing use of the evaluation paradigm of base asphalt in the field, which assumes that rubber-modified asphalt can be regarded as a homogeneous asphalt with improved performance, while ignoring the essential characteristics of its two-phase composite system. In reality, the rubber phase and the asphalt phase evolve independently, and there is dynamic material exchange and chemical reaction between the two phases. This determines that no overall index can uniquely correspond to the intrinsic state of the degree of rubber-asphalt reaction.

[0005] Following conventional technical approaches, solving the problem of determining regeneration timing naturally leads to the idea of ​​adding more overall performance indicators, improving testing accuracy, extending the aging observation period, or combining multiple indicators into empirical formulas to try to find a certain threshold through data fitting. However, this approach has a fundamental obstacle because no matter how many overall indicators are tested, each indicator is a superposition of PE and IE, and the evolution direction of PE and IE with the aging process is not monotonous (for example, the low-temperature interaction effect may change from damage to improvement, while the high-temperature particulate effect may change from improvement to damage), and their dominance can even reverse in different temperature ranges. Without decoupling, any threshold judgment based on overall indicators will fail due to the switching of mechanisms in different aging stages and temperature ranges; the same overall value may correspond to completely different degrees of response.

[0006] Therefore, simply relying on traditional approaches to repair the problem cannot break through the bottleneck. It is necessary to develop a separation-decoupling-quantification method to accurately determine the reaction progress. Summary of the Invention

[0007] One of the objectives of this invention is to provide a method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of rubber-asphalt reaction, in order to solve the technical problem that the degree of rubber-asphalt reaction cannot be quantitatively evaluated and the timing of regeneration lacks scientific basis in the prior art.

[0008] To achieve the above-mentioned objectives, the specific technical solution is as follows: A method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of rubber asphalt reaction includes the following steps: S1 Obtain rubber-modified asphalt samples and base asphalt of the same origin as the rubber-modified asphalt; both the rubber-modified asphalt samples and the base asphalt have multiple aging degrees, including the unaged state and different aging states after aging treatment; the aging treatment is: short-term aging at 163℃ for 85min using RTFO; or short-term aging at 163℃ for 85min using RTFO, followed by aging at 100℃ and 2.1MPa under PAV conditions for 20h~80h; S2 performs phase separation on rubber-modified asphalt samples under each aging state at a temperature greater than or equal to 155℃ and less than 180℃ to obtain asphalt phase and rubber phase. S3 conducted rheological property tests on the rubber-modified asphalt, the asphalt phase, and the matrix asphalt under preset temperature conditions of high temperature, medium temperature, and low temperature, respectively: the irreversible creep compliance J was obtained under high temperature conditions. nr The fatigue life N obtained by time scanning under medium temperature conditions was obtained. f The ratio of low-temperature creep stiffness S to creep rate m, S / m, was obtained by testing under low-temperature conditions, and the corresponding rheological performance index values ​​of the three were obtained. S4 calculates the particle effect value PE and the interaction effect value IE under each aging state according to equations (1) and (2) for each temperature domain: Equation (1); Equation (2); In the formula, Unfiltered is the rheological performance index value of the rubber-modified asphalt, Filtered is the rheological performance index value of the asphalt phase, and Neat is the rheological performance index value of the base asphalt. Among them, PE is defined as the contribution of rubber particles insoluble in the asphalt phase to the rheological properties of the system, and IE is defined as the change in intrinsic properties of the asphalt phase caused by the interaction between rubber and asphalt through material exchange and chemical reaction; the combined evolution trend of PE and IE characterizes the degree of rubber-asphalt reaction. S5 based on high temperature J nr The numerical signs and trends of the corresponding particle effect PE_H, the high-temperature interaction effect IE_H, and the low-temperature interaction effect IE_L with the degree of aging are used to divide the aging process of rubber-modified asphalt into three stages to evaluate the degree of rubber-asphalt reaction, and to determine the timing of recycling based on the divided aging stages: When IE_H<0 and IE_L>0, it is determined to be the first stage dominated by asphalt oxidation hardening and rubber swelling absorption, and no recycling treatment needs to be initiated. When IE_H<0 and IE_L<0, it is determined to be the second stage of dynamic competition between rubber degradation and asphalt aging, and the stage of recommending recycling treatment is entered. When PE_H>0 and IE_H>0, it is determined to be the third stage dominated by aging of the rubber-asphalt blend, entering the regeneration stage of restoring the overall performance of the blend. This regeneration stage indicates that the soluble rubber components have been largely depleted. The determination of the third stage also utilizes medium-temperature N... f The corresponding PE and IE are used for auxiliary verification: when the temperature is N f When the corresponding PE value decreases by more than 30% compared to the second stage, and the corresponding IE value shows a continuous increasing trend, it can be used to confirm that the rubber-asphalt reaction has entered the third stage.

[0009] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects: In the field of road engineering, the aging of rubber-modified asphalt involves three independent variables: asphalt oxidative hardening, rubber swelling / degradation, and two-phase mass exchange. Existing technologies can only obtain overall rheological properties such as J. nrThe continuous decline was misinterpreted as an improvement in high-temperature performance, failing to distinguish between the particle effect (PE, the physical contribution of rubber) and the interaction effect (IE, the chemical contribution), and further failing to capture the key turning points in the reaction mechanism, such as the change from positive to negative IE_L and from negative to positive PE_H. This resulted in the inability to quantitatively evaluate the degree of rubber-asphalt reaction, and a lack of scientific basis for judging the timing of recycling.

[0010] This invention separates the asphalt phase through phase separation, multi-temperature rheology, and PE / IE decoupling techniques, and then tests the high-temperature J of the homologous matrix asphalt NA. nr , medium temperature N f Low-temperature S / m. Using the PE and IE formulas, the particle effect and interaction effect are independently quantified from the overall performance. The NA of the homologous matrix asphalt is used as the zero-interaction benchmark, freeing IE from dependence on absolute values. Aging is divided into three stages based on three combinations of IE_H and IE_L, with sign reversal directly corresponding to qualitative changes in the reaction mechanism (swelling and oil absorption, degradation and migration, and blend hardening). The synergistic effect of multi-temperature zone indices captures the temperature asynchrony of high-temperature benefit and low-temperature damage. The cross-validation of PE / IE with solubility S and expansion rate E (the nodes where IE_L turns from positive to negative and E turns from positive to negative are completely consistent in time; the positive turn of PE_H is synchronous with S approaching saturation) forms a macro-rheological-micro-physicochemical dual-dimensional verification.

[0011] This invention creatively integrates phase separation operation with multi-temperature zone rheological property testing of separated components. By establishing two quantitative formulas for PE and IE, it simultaneously solves two interrelated but long-standing technical problems: the inability to quantitatively evaluate the degree of rubber-asphalt reaction and the inability to accurately determine the timing of regeneration based on the degree of reaction.

[0012] The invention comprises three stages: the first stage (physical swelling) requires no regeneration, only the reservation of light components in the formulation; the second stage (degradation competition) is the active regeneration window, and a composite strategy of supplementing light components and repairing the rubber network should be adopted; the third stage (blend aging) requires reconstruction and regeneration. This invention uses a symbolic criterion, does not rely on numerical thresholds, has material universality, and the auxiliary criterion for medium-temperature PE can accurately capture the critical point of rubber elasticity loss.

[0013] In summary, the present invention solves two major technical problems: the inability to quantitatively evaluate the degree of reaction and the inability to determine the timing of regeneration based on the degree of reaction. It provides a scientific basis for the phased and precise regeneration of aged rubber-modified asphalt.

[0014] According to one embodiment of the present invention, the rubber-modified asphalt samples with different aging degrees are named CRMA; the matrix asphalt of the same origin as the rubber-modified asphalt is named NA.

[0015] According to one embodiment of the present invention, the aging process is as follows: CRMA and NA are subjected to short-term aging in a rotary thin-film oven at 163°C for 85 minutes to obtain CRMA and NA aged at 163°C for 85 minutes; CRMA and NA are first subjected to short-term aging in a rotary thin-film oven at 163°C for 85 minutes, and then aged under a pressure aging vessel at 100°C and 2.1 MPa for 20 hours, 40 hours, 60 hours, and 80 hours respectively, thereby obtaining CRMA and NA aged at 100°C for 20 hours, 100°C for 40 hours, 100°C for 60 hours, and 100°C for 80 hours; a total of 5 groups of CRMA and NA with different aging degrees are obtained. Wherein, RTFO is a rotary thin-film oven, and PAV is a pressure aging vessel.

[0016] According to one embodiment of the present invention, the rubber-modified asphalt sample is prepared by the following method: the base asphalt is heated to a molten state in an oven at 140℃-160℃, and then transferred to a constant temperature electric heating mantle to continue heating to 180℃-190℃. Under constant temperature conditions of 180℃-190℃, waste rubber particles accounting for 18%-22% of the asphalt mass are added while stirring; a high-speed shearing machine is used to shear at a speed of 4400r / min-4600r / min for 8min-12min; after shearing, stirring is continued at 180℃-190℃ for 25min-35min.

[0017] According to one embodiment of the present invention, the phase separation in S2 specifically adopts the high-temperature mesh sieve percolation method: the rubber modified asphalt sample is placed on a 200-300 mesh standard sieve, a collection container is set below it, and the whole thing is placed in an oven at 160±5℃ for 30±5 min to collect the asphalt phase.

[0018] Among them, the viscosity of the asphalt phase decreases at high temperatures, allowing it to permeate through the screen, while the rubber particles are trapped by the screen due to their particle size and swelling state, thus achieving physical separation of the two phases. It is important to note that the high-temperature separation operation itself introduces a new technical problem: the thermal effects during the separation process may cause non-negligible additional aging of the asphalt phase. This results in the separated asphalt phase failing to accurately reflect its intrinsic properties in the original rubber-modified asphalt, ultimately distorting the calculated results for PE and IE, and rendering the aging stage assessment invalid. To address this newly introduced problem, this invention strictly limits the process parameters for phase separation, setting the separation temperature at 160±5℃ and the holding time at 30±5min. Through these optimized parameters, while ensuring sufficient flow of the asphalt phase for effective separation, the occurrence of additional thermo-oxidative aging is suppressed to the greatest extent, thereby ensuring the fidelity of the separated asphalt phase and solving the new problem of additional aging introduced by high-temperature separation.

[0019] According to one embodiment of the present invention, step S2 further includes the separation of the rubber phase: a rubber-modified asphalt sample is weighed and dissolved in trichloroethylene, stirred at 45℃-55℃, vacuum filtered through a filter membrane, and the retained rubber particles are dried by forced air to obtain the rubber phase. This invention solves the technical problems of not being able to completely obtain a pure rubber phase and the difficulty in verifying the degree of reaction from the perspective of the rubber phase, providing a component basis for multi-dimensional cross-validation.

[0020] According to one embodiment of the present invention, the rotation speed of the magnetic stirring is 600 r / min-800 r / min, and the magnetic stirring time is 12h-13h.

[0021] According to one embodiment of the present invention, the filter membrane is a 0.010 mm filter membrane.

[0022] According to one embodiment of the present invention, the drying temperature of the retained rubber particles is 40℃-60℃ and the drying time is 12h-24h; preferably, the drying temperature of the retained rubber particles is 50℃ and the drying time is 24h.

[0023] According to one embodiment of the present invention, a multi-dimensional cross-validation step is further included: based on the rubber phase obtained in S2, the mass m of the dried rubber phase is obtained. R 1. The initial mixing mass is m0. Calculate the solubility S = (m0 – m R ) / m0×100%; the average particle area S of the separated rubber phase R The expansion rate E is calculated based on the average area S0 of the original rubber particles. R –S 0) / S0×100%; Combining the changes in solubility S and swelling rate E with the degree of aging, cross-validation was performed with PE and IE to achieve a multi-dimensional evaluation of the degree of rubber-asphalt reaction. Solubility S reflects the mass loss of rubber (degree of cross-linking network breakage), and swelling rate E reflects the volume change of rubber. The evolution of S and E is highly synchronized with PE / IE; the node where IE_L changes from positive to negative coincides perfectly with the node where E changes from positive to negative in time. In the third stage, S approaches the theoretical upper limit synchronously with the positive changes in PE_H and IE_H. This consistency provides rheological-independent verification evidence, enhancing the reliability of the evaluation system.

[0024] According to one embodiment of the present invention, the average particle area S R The following method was used to obtain S2: After obtaining the rubber phase, the average particle area of ​​the rubber phase was determined by microscopy. The rubber phases separated under each aging state were placed on glass slides to prepare observation samples. Microscopic images were acquired at 50x magnification. ImageJ image analysis software was used to statistically analyze the area of ​​1000 randomly selected rubber particles in each sample to obtain the average particle area S.R .

[0025] According to one embodiment of the present invention, the separation temperature of the phase separation in S2 is not higher than the aging temperature of the rotary thin film oven, so as to prevent the separation process from causing measurable additional aging to the asphalt phase.

[0026] According to one embodiment of the present invention, the high temperature in S3 is 60℃-65℃; the medium temperature is 20℃-25℃; and the low temperature is -10℃ to -20℃; preferably, the high temperature is 65℃; the medium temperature is 25℃; and the low temperature is -20℃.

[0027] According to one embodiment of the present invention, in the calculation of PE and IE in S4, for the performance improvement direction of the index J, which is a decrease in value... nr S / m, negative PE or IE indicate a positive contribution; for performance improvement indicators N, the direction is towards numerical increase. f A positive PE or IE indicates a positive contribution.

[0028] According to one embodiment of the present invention, S5 further includes a third-stage auxiliary verification rule: when any of the following conditions are met, it can be confirmed that the rubber-asphalt reaction has entered the third stage: 1. High temperature J nr The corresponding PE_H value changes from negative to positive; 2.Medium temperature N f The corresponding PE value decreased by more than 30% compared to the previous aging level, and the corresponding IE value showed a continuous increasing trend.

[0029] Among these, the loss of elasticity in rubber particles is the core indicator of entering the third stage. At high temperatures, the change from negative to positive PE directly reflects the transition from increased elasticity to rigidity damage in the particles. Mid-temperature fatigue performance is highly dependent on the elastic energy dissipation effect of the rubber particles; a significant decrease in PE corresponds to the depletion of the rubber's elastic core. Both can independently confirm the arrival of the reaction's final stage. This invention further defines the criteria for determining the third stage, resolving the potential ambiguity in stage determination that may exist solely based on the high-temperature IE criterion, providing auxiliary verification criteria, and improving the accuracy of the third-stage determination.

[0030] According to one embodiment of the present invention, S5, determining the regeneration timing based on the degree of reaction, further includes matching corresponding regeneration strategies in stages: When it is determined to be in the first stage, the swelling balance can be controlled by reserving a surplus of light components in the initial formula design or by optimizing the preparation process parameters, without the need to start a special regeneration process. When it is determined to be the second stage, a composite regeneration strategy with the core of supplementing light components and repairing the rubber crosslinking network is adopted; When the stage is determined to be the third stage, a reconstruction and regeneration strategy is adopted, which is based on chemical regeneration using the surface active sites of residual degradation products or the introduction of exogenous polymers to construct new elastic networks.

[0031] Because the core issues differ at different aging stages, the first stage involves the normal physical phenomenon of light component migration, requiring only pre-regulation without regeneration; the second stage allows for rubber repair and still offers room for improvement in interaction effects, making it suitable for actively repairing biphase properties; the third stage requires the rubber to have failed, necessitating performance reconstruction at the blend level. Therefore, this invention solves the problem of a one-size-fits-all approach in existing regeneration technologies, avoiding the technical issues of poor regeneration results or resource waste caused by the inability to match differentiated regeneration strategies to different reaction stages.

[0032] The second objective of this invention is to provide an application of the method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of reaction of the rubber asphalt.

[0033] The specific technical solution is as follows: The method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of rubber-asphalt reaction is applied in the staged and precise regeneration of aged rubber-modified asphalt. This method evaluates the degree of rubber-asphalt reaction and determines the timing of regeneration, implementing a corresponding staged regeneration strategy based on the determined aging stage.

[0034] According to one embodiment of the present invention, the staged precise regeneration includes: when it is determined to be the second stage, a composite regeneration strategy of supplementing lightweight components and repairing the rubber crosslinking network is adopted; when it is determined to be the third stage, a reconstruction regeneration strategy of using the surface active sites of residual degradation products for chemical regeneration or introducing exogenous polymers to construct a new elastic network is adopted.

[0035] According to one embodiment of the present invention, using PE and IE in an unaged state as a benchmark, the degree of rubber-asphalt reaction is quantified by comparing the changes in PE and IE relative to the benchmark under each aging state.

[0036] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0037] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart illustrating the method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of reaction of rubber asphalt in the embodiments.

[0038] Figure 2 This is a schematic diagram of the asphalt phase separation device in the embodiment.

[0039] Figure 3 This is a schematic diagram of the rubber phase separation device in the embodiment.

[0040] Figure 4 This is a schematic diagram illustrating the physical meaning of PE and IE in the embodiment. Detailed Implementation

[0041] The terms "preferred," "more preferred," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0042] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present invention.

[0044] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0045] In the embodiments, rubber-modified asphalt samples with different aging degrees are named CRMA; the base asphalt of the same origin as the rubber-modified asphalt samples is named NA.

[0046] The base asphalt used in this embodiment is 70# petroleum asphalt produced by Maoming Petrochemical Co., Ltd., and its basic properties are shown in Table 1 below: Table 1 Basic Properties of 70# Base Asphalt

[0047] The rubber powder used in this embodiment is derived from waste tires of heavy-duty trucks with dimensions of 900mm to 1200mm, with a mesh size of 30 to 80 mesh, and was produced and supplied by Guangxi Jiaoke New Material Technology Co., Ltd. The particle size range of the waste rubber used in this embodiment is 0.45mm to 0.6mm. The composition of the waste rubber is summarized in Table 2.

[0048] Table 2 Basic Physicochemical Indicators of Rubber

[0049] In this embodiment, the rubber-modified asphalt sample was prepared by the following method: the base asphalt was heated to a molten state in an oven at 150°C, and then transferred to a constant-temperature electric heating mantle to continue heating to 185°C. Under constant temperature conditions of 185°C, waste rubber particles accounting for 20% of the asphalt mass were added while stirring, and stirring was continued for 20 minutes; then, a high-speed shearing machine was used to shear at 4500 r / min for 10 minutes; after shearing, stirring was continued at 185°C for 30 minutes.

[0050] Example The method for determining the degree of reaction of rubber asphalt and the timing of recycling of aged rubber-modified asphalt is shown in the flowchart below. Figure 1 As shown, it includes the following steps: S1 subjected rubber-modified asphalt samples and base asphalt of the same origin as the above rubber-modified asphalt samples to the following aging treatments: short-term aging at 163℃ for 85 min with RTFO to obtain the short-term aging group; short-term aging at 163℃ for 85 min with RTFO, followed by aging at 100℃ and 2.1MPa PAV for 20 h, 40 h, 60 h, and 80 h respectively, thus obtaining a total of 6 groups of rubber-modified asphalt samples CRMA with different aging degrees, namely unaged, aged at 163℃ for 85 min, aged at 100℃ for 20 h, aged at 100℃ for 40 h, aged at 100℃ for 60 h, and aged at 100℃ for 80 h, and the corresponding base asphalt NA; S2 uses a high-temperature mesh sieve percolation method to separate the asphalt phase of CRMA under various aging conditions: 100g of CRMA sample is placed on a collection container covered with a 300-mesh stainless steel sieve and kept in a 160℃ oven for 30 minutes. The component flowing to the bottom of the container is collected, which is the asphalt phase (CR-A). 1g of CRMA sample under each aging condition is weighed and dissolved in 100mL of trichloroethylene. The solution is then magnetically stirred at 800r / min for 12h in a 50℃ constant temperature water bath to ensure complete dissolution of the asphalt. The resulting solution is vacuum filtered through a 0.010mm filter membrane. The filter paper containing rubber particles is transferred along with the particles to a petri dish and dried in a 50℃ forced-air drying oven for 24h to obtain the rubber phase. The mass m of the dried rubber phase is weighed. R Based on the original rubber blending mass m0 during CRMA preparation, the solubility S is calculated according to formula (3): S=(m0–m R ) / m0×100%(3; Meanwhile, the average particle area of ​​the rubber phase was determined using microscopy. Rubber phases separated under various aging conditions were placed on glass slides to prepare observation samples. Microscopic images were acquired at 50x magnification. ImageJ image analysis software was used to statistically analyze the area of ​​1000 randomly selected rubber particles from each sample, yielding the average particle area S. R Based on the average area S0 of the original rubber particles, the expansion rate E is calculated according to formula (4): E=(S R –S0) / S0×100%(4; The calculation results of solubility S and swelling rate E of rubber phase in rubber-modified asphalt under different aging degrees are summarized in Table 4; The schematic diagram of the asphalt phase separation device is shown below. Figure 2 As shown; The schematic diagram of the rubber phase separation device is shown below. Figure 3 As shown; S3 underwent a multi-stress creep recovery test at a high temperature of 64℃, referring to AASHTOT 350-19, and the unrecoverable creep compliance J at a stress level of 3.2 kPa was taken. nr J nr The smaller the value, the better the high-temperature rutting resistance.

[0051] Time-scan fatigue testing was conducted at a moderate temperature of 25°C using a dynamic shear rheometer with a 2mm thick, 8mm diameter specimen, a frequency of 10Hz, and a 5% strain control mode. The complex shear modulus G was used as the basis for the stress test. The number of loading cycles reduced to 50% of the initial value is taken as the fatigue life N. f N f The larger the value, the better the fatigue performance.

[0052] At a low temperature of -12℃, referring to the AASHTOT313-19 bending beam rheological test, the ratio of creep stiffness S to creep rate m, S / m, was obtained. The smaller the S / m, the better the low temperature crack resistance. S4 calculates the particulate effect (PE) and interaction effect (IE) under each temperature range and aging state according to equations (1) and (2), respectively. The physical meaning of PE and IE is illustrated in the diagram below. Figure 4 As shown; Note: For J nr For S / m, a decrease in the value indicates performance improvement, and a negative PE or IE indicates a beneficial contribution; for N f An increase in the value indicates performance improvement, and a positive PE or IE indicates a beneficial contribution. The calculation results are summarized in Table 3: Equation (1); Equation (2); In the formula, Unfiltered is the rheological performance index value of rubber-modified asphalt, Filtered is the rheological performance index value of the asphalt phase, and Neat is the rheological performance index value of the base asphalt. Among them, PE is defined as the contribution of rubber particles insoluble in the asphalt phase to the rheological properties of the system, and IE is defined as the change in intrinsic properties of the asphalt phase caused by the interaction between rubber and asphalt through material exchange and chemical reaction; the combined evolution trend of PE and IE characterizes the degree of rubber-asphalt reaction. S5 based on high temperature J nr The numerical signs of the corresponding particle effect PE_H, high-temperature interaction effect IE_H, and low-temperature interaction effect IE_L, along with their changing trends with aging degree, are used to divide the aging process of rubber-modified asphalt into three stages to evaluate the degree of rubber-asphalt reaction. Based on these aging stages, the timing of recycling is determined. When IE_H<0 and IE_L>0, it is determined to be the first stage of asphalt oxidation hardening and rubber swelling absorption (corresponding to the aging state in Table 3: unaged, RTFO), and no regeneration treatment needs to be initiated. When IE_H<0 and IE_L<0, it is determined to be the second stage of dynamic competition between rubber degradation and asphalt aging (corresponding to the aging states in Table 3: PAV20h, PAV40h, PAV60h), and it enters the stage where it is recommended to carry out recycling treatment. When PE_H>0 and IE_H>0, it is determined to be the third stage dominated by aging of the rubber-asphalt blend, entering the regeneration stage of restoring the overall properties of the blend. The above-mentioned regeneration stage of restoring the overall properties of the blend indicates that the soluble components of rubber have been basically depleted. The determination of the third stage also uses medium-temperature N f The corresponding PE and IE are used for auxiliary verification: when the temperature is N f When the corresponding PE value decreases by more than 30% compared to the second stage, and the corresponding IE value shows a continuous increasing trend, it can be used to confirm that the rubber-asphalt reaction has entered the third stage.

[0053] Table 3 Calculation results of PE and IE

[0054] Table 3 shows that in the first stage, the index IE_H < 0, indicating that after the rubber particles absorb the light components, the components remaining in CR-A (the separated asphalt phase) are mainly heavy components. This increases the viscosity and stiffness of CR-A, and the non-recoverable creep flexibility J at high temperatures. nrThe NA of the base asphalt was significantly lower than that of the base asphalt. Therefore, the asphalt phase re-weighting caused by material migration had a positive effect on the high-temperature rutting resistance, and the interaction effect showed a significant improvement. Numerically, the absolute value of IE_H (0.7469) before aging was much larger than that of PE (0.1987), proving that the improvement in high-temperature performance at this stage mainly depended on the interaction effect caused by swelling absorption, rather than the physical effect of the rubber particles themselves. In the first stage, the index IE_L > 0, indicating that the rubber particles "extracted" the lightweight components from the asphalt, which originally played a role in softening and relaxing, causing the separated CR-A to become more brittle and hard. At low temperatures, the stiffness S of this asphalt phase, which has lost its lightweight components, increases, while the creep rate m decreases, resulting in an overall increase in the S / m value compared to NA. Therefore, the interaction effect has a negative contribution to low-temperature performance in this stage (IE_L is positive, and the smaller the performance index S / m, the better). It is worth noting that although the interaction effect impairs low-temperature performance, the PE_L at the unaged stage is -1.3741 (a very large absolute value). The elastic containment and toughening effect of the rubber particles themselves compensate for the negative effect of IE, allowing CRMA to still maintain good low-temperature performance overall.

[0055] In the second stage, the key point for IE_L to turn from positive to negative is PAV20h, which is the critical point where the interaction effect shifts from unfavorable to favorable in terms of low-temperature performance (IE_L≈0). As aging continues, the light components absorbed and locked by the rubber particles, along with the degradation products of the rubber itself, begin to gradually migrate back and be released into the asphalt phase. These migrated light components play a role in replenishing the flexibility of the asphalt phase and enhancing its low-temperature relaxation ability. As a result, the low-temperature performance of CR-A not only recovers the losses caused by "extraction" but even begins to outperform NA itself, and IE_L thus turns negative. After PAV40h, the absolute value of IE_L (0.3670) has exceeded the absolute value of PE_L (0.1373), indicating that the interaction effect has replaced the particle effect and become the dominant mechanism for improving low-temperature performance. In the second stage, IE_H < 0 indicates that at the high-temperature end, although the interaction effect is still beneficial, its improving effect reaches its extreme value (-0.9229) after PAV20h and then continuously weakens with increasing aging. This reflects the fierce competition between two opposing trends: asphalt oxidative hardening and rubber degradation softening. On the one hand, the long-term high-temperature and high-pressure environment causes the asphalt phase itself to continuously oxidize, J nr Natural descent; on the other hand, the light components of rubber reversion have a plasticizing effect on the asphalt phase, causing J nr The relative increase. The net effect of both determines the value of IE_H. The decrease in the absolute value of IE_H after 40 hours of PAV is a result of the intrinsic oxidative hardening of asphalt gradually gaining the upper hand.

[0056] Meanwhile, in the second stage, the PE value at medium temperature was consistently much higher than the IE value, demonstrating the core dependence of fatigue performance on the rubber particle effect. It is noteworthy that at PAV60h, the PE value showed a significant jump (27.7321), while N... f The IE also continued to increase, which may reflect that the refined rubber particles formed a better interfacial bond and stress transfer with the matrix, providing an additional fatigue energy dissipation mechanism.

[0057] In the third stage, PE_H > 0 because, after a long period of thermo-oxidative degradation, the cross-linked network of the rubber particles has been almost completely destroyed, and a large number of molecular chains have broken, resulting in a substantial loss of high elasticity. At this point, the rubber particles are no longer elastomers but have degenerated into rigid or even brittle filler particles. In the third stage, IE_H>0 changed from negative to positive, indicating that the rubber particle effect itself also impaired high-temperature performance. This further confirms that the rubber particles have degenerated into rigid fillers. Under repeated creep loading, these rigid particles that cannot recover elastically produce irreversible displacement and interfacial debonding in the asphalt matrix, increasing irreversible deformation; Furthermore, in the early to mid-aging stages (0-60h), PE_H is negative because the rubber particles still retain elasticity. However, as aging progresses into the later stages (third stage, 80h), the rubber degrades severely, the cross-linking network disintegrates, and the particles essentially lose their elasticity, becoming rigid fillers. At this point, these rigid particles not only can no longer provide elastic support but also disrupt the continuity of the asphalt phase, exacerbating irreversible viscous flow and leading to a decrease in the J of CRMA. nr Instead, it becomes greater than CR-A, and PE_H suddenly turns positive. This abrupt change from negative to positive is also a sign that the system has entered the third stage; Meanwhile, in the third stage, the degradation of medium-temperature PE can be used as an auxiliary criterion. From PAV60h to PAV80h, the medium-temperature PE dropped sharply from 27.7321 to 17.3143, a decrease of more than 37%, far exceeding the 30% auxiliary criterion threshold. This confirms the loss of the elastic core of the rubber particles, resulting in a significant decrease in their ability to dissipate fatigue energy, supporting the determination of the third stage.

[0058] Table 4 Calculation results of solubility S and swelling ratio E

[0059] Note: The rubber particles obtained after aging PAV60h and PAV80h were too small to be effectively placed on a glass slide for sample preparation, hence the missing expansion rate (E) data. This unmeasurability itself is important information about the physical state.

[0060] Table 4 shows that for unaged rubber and RTFO (first stage), the solubility S is low, at 7.62% for unaged rubber and only slightly increases to 12.77% after RTFO. This small increase indicates that the rubber cross-linking network is basically intact. The expansion rate E is positive and high, confirming that the rubber particles are in a state of significant volume expansion and the cross-linking structure is relatively intact. Specifically, the slow increase in S and the high positive value of E confirm that the rubber in the first stage of aging is mainly characterized by physical swelling, with minimal degradation. This is completely consistent with the first stage defined by the rheological criteria IE_H<0 and IE_L>0. For PAV20h, PAV40h, and PAV60h (the second stage), the solubility S shows a sharp increase: from 12.77% of RTFO to 30.47% of PAV20h, reaching 45.63% of PAV40h, and further increasing to 56.96% of PAV60h; the expansion rate E changes from positive to negative and drops sharply: PAV20h drops to -19.46%, and PAV40h further falls to -73.81%. PAV40h already enters the volume shrinkage limit region. The rapid increase in S and the sharp decrease in E, both confirming that the rubber has transitioned from physical swelling to chemical degradation. This is highly consistent with the second stage defined by the rheological criteria IE_H < 0 and IE_L < 0. PAV20h is the node where the E sign reverses and also the starting point where the IE_L sign reverses; the two are completely synchronized.

[0061] For PAV80h (stage three), the solubility S increased slightly from 56.96% in PAV60h to 61.39% in PAV80h, an increase of only 4.43%, with the growth rate slowing significantly. The expansion rate E for both PAV60h and PAV80h was unmeasurable due to the excessively small size of the rubber particles. The slowing growth rate of S, approaching its theoretical limit, and the unmeasurable E due to the extremely small particle size, together confirm that the rubber reaction has entered its final state. This perfectly corresponds to the third stage defined by the rheological criterion IE_H>0.

[0062] By combining the physicochemical indices of the rubber phase (solubility S, swelling rate E) in Table 4 with the rheological dual-effect indices (PE, IE) in Table 3, this invention constructs a multi-dimensional evaluation system with cross-validation of macroscopic performance and microscopic physicochemical properties. The comprehensive evaluation of each stage is shown in Table 5 below.

[0063] Table 5 Multi-dimensional evaluation system

[0064] Comparative Example 1 Comparative Example 1 provides a traditional evaluation method that does not involve phase separation. The only difference from the embodiment is that the asphalt phase separation and rubber phase separation in S2 of the embodiment are omitted in Comparative Example 1. Rheological tests are directly performed on the original CRMA samples under different aging conditions, and the degree of aging is evaluated only based on the changes in these overall rheological indicators.

[0065] Specifically: The CRMA samples were prepared, aged (no aging, RTFO, PAV 20h, PAV 40h, PAV 60h, PAV 80h), and subjected to rheological testing conditions identical to those in the examples, but without any phase separation treatment. High-temperature J values ​​of the original CRMA samples under each aging condition were directly obtained. nr , medium temperature N f The results for low temperature S / m are shown in Table 6.

[0066] Table 6. CRMA rheological properties under different aging conditions

[0067] Note: J nr The smaller the value, the better the high-temperature rutting resistance; N f The larger the value, the better the medium-temperature fatigue performance; the smaller the value, the better the low-temperature crack resistance.

[0068] Based on the monotonic variation trends of each indicator with the degree of aging in Table 6, the following evaluation conclusions can be drawn: High temperature performance (J) nr ): J nr 0.392 kPa before aging -1 The pressure continued to decrease to 0.011 kPa at PAV80h. -1 The decrease reached 97.2%. According to traditional interpretation, J nr The continuous decrease indicates that the high-temperature rutting resistance continues to improve with increasing aging. Based on this trend, traditional methods would conclude that the deeper the aging, the better the high-temperature performance, thus classifying the PAV80h sample as having the best high-temperature performance.

[0069] Mid-temperature performance (N) f ): N f The number of cycles decreased from 52,809 at no aging to 10,680 at PAV 80h, a decrease of 79.8%. However, it is worth noting that N... f Not monotonically decreasing: N at PAV60h fThe fatigue life was 17,400 cycles, a significant decrease from the 23,970 cycles at PAV40h, and further reduced to 10,680 cycles at PAV80h. Traditional methods can only observe the overall trend of fatigue life gradually decreasing with aging, but cannot explain whether there are beneficial mechanisms involved in the degradation process, nor can they identify the key nodes at which fatigue performance undergoes qualitative changes.

[0070] Low temperature performance (S / m): The S / m value continuously increased from 151.7 MPa / s at no aging to 477.4 MPa / s at PAV80h, an increase of 214.7%. Traditionally, this continuous increase in S / m indicates a sustained deterioration in low-temperature crack resistance. Traditional methods use this to determine that deeper aging leads to worse low-temperature performance, but they cannot identify whether the improvement mechanism changes at a certain stage.

[0071] Aging stage classification based on overall indicators: Based solely on the data in Table 6, traditional methods can only subjectively segment the data according to the magnitude of each indicator's value, for example, by J. nr The rate of decline roughly divides the aging process into a rapid hardening phase (unaged → RTFO, J nr A sharp drop of 77% and a slow hardening period (PAV 20~80h, J nr (The rate of decline is slowing down), or according to N f The attenuation range is similarly divided. This division ignores the intrinsic structural evolution of the rubber-asphalt two-phase system and fails to reveal the fundamental driving force behind performance changes.

[0072] Furthermore, comparing the overall rheological parameters in Table 6 with the PE / IE decoupling results in Table 3 of the example clearly reveals the following limitations of the traditional method: Limitation 1: Inability to identify directional shifts in interaction effects Table 6 shows that the low-temperature S / m of CRMA continuously increases with aging, and traditional methods can only conclude that the low-temperature performance deteriorates monotonically. However, Table 3 records that the examples reveal a completely different intrinsic mechanism through phase separation. The interaction effect IE_L undergoes a directional reversal from positive to negative during RTFO to PAV20h (from impairing low-temperature performance to improving low-temperature performance). This key reversal is completely masked in the overall indicators of Table 6 because the decrease in the rubber particle effect PE is greater, obscuring the beneficial transformation of IE.

[0073] Limitation 2: Inability to distinguish the dominant contributors to performance changes Table 6 shows the J values ​​of PAV60h and PAV80h. nr The values ​​are 0.023 kPa. -1 and 0.011 kPa -1Traditional methods use this to determine if high-temperature performance continues to improve. However, Table 3 of the examples reveals that PE_H and IE_H are negative at PAV 60h, but both PE_H and IE_H turn positive (0.8649 and 1.0270) at PAV 80h, indicating that both types of effects have become detrimental factors to high-temperature performance. nr The continued decline is entirely a result of the high hardening of the asphalt matrix, not a contribution from the rubber. Traditional methods misinterpret the hardening of the asphalt matrix as a continuous improvement in the system, completely obscuring the driving force behind the performance change.

[0074] Limitation 3: It cannot provide a mechanistic explanation for the complex evolution of intermediate-temperature fatigue life. Table 6 shows that N f From 23,970 cycles at PAV40h to 17,400 cycles at PAV60h, and then to 10,680 cycles at PAV80h, traditional methods can only describe accelerated decay. However, Table 3 of the examples shows that PE at intermediate temperatures is consistently much greater than IE, and PE jumps sharply at PAV60h (27.7321) before rapidly decaying at PAV80h (17.3143). This indicates that the fundamental driving force of fatigue performance is the rubber particle effect, and the sharp drop in PE originates from the loss of the rubber elastic core. Traditional methods cannot describe the overall N... f This core mechanism is stripped away from the changes.

[0075] Limitation 4: Inability to construct a multi-dimensional aging stage determination system Traditional methods rely solely on three independent overall indicators for empirical segmentation, lacking mechanistic criteria. For example, they cannot determine when the aging process transitions from "physical aging" to "chemical aging," nor can they ascertain whether rubber degradation has reached its final state. In contrast, the proposed method establishes a three-stage determination criterion based on the sign relationship between PE and IE, which can be cross-validated with physicochemical indicators such as solubility (S) and swelling ratio (E), forming a mechanistically transparent, multi-dimensional evaluation system.

[0076] Limitation 5: It cannot support the formulation of a phased regeneration strategy. Because traditional methods cannot reveal the dominant mechanisms in each stage of aging—namely, the first stage is dominated by asphalt oxidation and hardening and rubber swelling absorption; the second stage is dominated by the dynamic competition between rubber degradation and asphalt aging; and the third stage is dominated by the overall oxidation and hardening of the blend—it is impossible to formulate differentiated regeneration strategies targeting the core contradictions of each stage. Traditional methods can only apply a uniform regeneration approach to samples in all aging states, failing to distinguish when it is sufficient to reserve a surplus of light components in the initial formulation design and optimize the preparation process (first stage); when active regeneration centered on supplementing light components and repairing the rubber crosslinking network should be initiated (second stage); and when a reconstruction regeneration aimed at rebuilding the elastic skeleton of the blend is needed (third stage). This one-size-fits-all regeneration approach may waste resources unnecessarily and may miss the optimal intervention opportunity when targeted regeneration is truly needed.

[0077] The comparison between Comparative Example 1 and the Example 2 is summarized in Table 7.

[0078] Table 7 Comparison between Comparative Example 1 and the Examples

[0079] In summary, Comparative Example 1 fully demonstrates that traditional evaluation methods without phase separation treat rubber-modified asphalt as a "homogeneous black box," only observing the final macroscopic performance and failing to provide a mechanistic basis for accurate determination of the aging stage or decision support for the scientific formulation of a phased regeneration strategy. The proposed example, through phase separation and dual-effect decoupling, fundamentally overcomes these limitations, achieving accurate evaluation of the degree of aging reaction and quantitative judgment of regeneration timing, demonstrating significant progress.

[0080] Comparative Example 2 The only difference between Comparative Example 2 and the Example is that, during the asphalt phase separation in S2, the oven temperature in Comparative Example 2 was increased from 160°C in the Example to 180°C. All other operations (sample preparation, aging treatment, rubber phase separation, rheological testing conditions, PE / IE calculation method, etc.) are exactly the same as those in the Example.

[0081] This comparative example only focuses on the three aging states that best reflect the effect of temperature: no aging, RTFO, and PAV20h. ​​The rheological test conditions are the same as those in the example. The high-temperature and low-temperature rheological performance indicators of CRMA, CR-A separated at 180℃ and the corresponding aging state NA are obtained. PE and IE are calculated according to Equations (1) and (2). The results are summarized in Table 8.

[0082] Table 8. Calculation results of PE and IE in Comparative Example 2 (separation at 180°C) and their comparison with those of the Examples.

[0083] Table 8 shows the systematic biases of PE and IE under separation conditions of 180℃. Since Unfiltered (CRMA) and Neat (NA) in the calculation formulas for PE and IE are not affected by the separation temperature, all biases originate from the distortion of Filtered (CR-A).

[0084] As shown in Table 8, the PE and IE obtained by separation at 180℃ under the three aging conditions all exhibited regular deviations: Deviation analysis of high-temperature indicators: The absolute value of the negative PE_H value systematically decreases, leading to an underestimation of the contribution of rubber particle effect. This can easily result in a misjudgment that the physical contribution of rubber particles to high-temperature performance is not as large as expected. The absolute value of the negative IE_H value systematically increases, leading to an overestimation of the contribution of interaction effect. This can exaggerate the improving effect of rubber-asphalt interaction on high-temperature performance.

[0085] Analysis of deviations in low-temperature indices: The absolute value of the negative PE_L value systematically increased, leading to an overestimation of the improving effect of rubber particles on low-temperature performance, potentially masking the true trend of the rubber particle effect decaying with aging. The positive IE_L value systematically increased or had an incorrect sign. Taking the unaged sample as an example, IE_L changed from 1.2217 to 1.4919, a deviation of 0.2702. The S / m of the filtered sample increased due to additional aging, amplifying the positive value of IE and exaggerating the extent to which the interaction effect impaired low-temperature performance. More seriously, at PAV20h, the IE_L of the example was -0.0148 (negative, indicating that the interaction effect had turned into a benefit to low-temperature performance), while the IE_L of Comparative Example 2 was +0.0234 (still positive, indicating that the interaction effect was still impairing low-temperature performance). The sign of IE_L underwent a fundamental change, directly leading to serious errors in the subsequent aging stage determination.

[0086] The absolute values ​​of the deviations for PE and IE decrease with increasing aging (the deviation is largest for unaged samples, followed by RTFO, and smallest for PAV20h). This is because unaged samples are most sensitive to additional heat, resulting in the largest deviation; PAV20h samples are sufficiently aged, and the relative increment from the additional 30 minutes of heat treatment is small. However, the decrease in deviation does not mean it can be ignored; the sign error of IE_L at PAV20h is sufficient to invalidate the entire stage's determination.

[0087] As can be seen from the comparative analysis of Comparative Example 2 above, the present invention strictly limits the asphalt phase separation temperature to 160±5℃, which has sufficient experimental basis and theoretical support. The specific reasons are as follows: The standard short-term aging temperature for RTFO is 163℃, and the long-term aging temperature for PAV is 100℃. The upper temperature limit of 165℃ set in this invention is essentially the same as the RTFO temperature, thus creating a control boundary in the process to prevent additional aging. Since the separation temperature is not higher than the RTFO aging temperature, measurable thermo-oxidative aging of the asphalt phase by the separation process itself can be effectively avoided, ensuring that the separation operation does not introduce additional aging variables. In contrast, the 180℃ used in Comparative Example 2 is significantly higher than the RTFO temperature, causing the separation process to become a secondary accelerated aging of the asphalt phase. The obtained asphalt phase deviates from its true state in the original rubber-modified asphalt, violating the design principle of in-situ, non-destructive characterization of the phase separation method.

[0088] Regarding the lower limit of temperature, when the separation temperature is below 155℃, the viscosity of the asphalt phase in CRMA that has undergone long-term aging (such as PAV 20h and above) increases significantly, resulting in insufficient fluidity. It is difficult for the asphalt phase to pass through a 300-mesh sieve within the 30-minute holding time, leading to a lower asphalt phase yield, more residual rubber particles, and reduced separation completeness. This, in turn, affects the representativeness and repeatability of the PE and IE calculation results. When the separation temperature is above 165℃, as shown in Comparative Example 2, the thermal oxidation rate increases sharply, causing non-negligible distortions in the performance indicators of the separated asphalt phase. Systematic deviations appear in the PE and IE calculation results, particularly severely interfering with the determination of the turning point in the aging stage.

[0089] Therefore, 160±5℃ constitutes the optimal operating window between separation efficiency and result fidelity. Under the premise of ensuring that the asphalt phase has sufficient fluidity to achieve full separation, it minimizes the interference of additional thermo-oxidative aging on the true state of the asphalt phase, thus ensuring the data accuracy and stage determination reliability of the evaluation method of this invention from the source of the process.

[0090] Comparative Example 3 Comparative Example 3 provides a method for evaluating high-temperature rheological parameters using the conventional rutting factor. The only difference from the Example is that in the S3 high-temperature rheological test, the irreversible creep compliance J of the Example is used instead. nr Replace with conventional rutting factor G / sinδ, then, adaptively in S4, the calculation basis of PE and IE in the embodiment is replaced with G. / sinδ, the remaining operations (sample preparation, aging treatment, and phase separation) are exactly the same as in the examples. This comparative example focuses on comparing and analyzing three aging states: no aging, RTFO, and PAV20h.

[0091] Comparative Example 3 used the same CRMA, CR-A, and NA samples as the examples, and conducted dynamic shear rheological tests according to AASHTOT 315-22 standards at a high temperature of 64°C and a frequency of 10 rad / s to obtain the rutting factor G of the three samples under each aging condition. / sinδ 。 For G For / sinδ, an increase in the value indicates improved high-temperature rutting resistance, and a positive PE or IE indicates a beneficial contribution.

[0092] Based on testing and calculation, under various aging conditions, according to G... The PE and IE results for / sinδ are compared with those in Table 3 of the examples based on J. nr The comparison of PE and IE results is summarized in Table 9.

[0093] Table 9 Based on G High-temperature PE and IE results calculated by / sinδ

[0094] Based on the data in Table 9, combined with the G values ​​of CRMA, CR-A, and NA under various aging conditions... The intrinsic relationship between the measured values ​​of / sinδ can reveal the G / sinδ has the following inherent limitations in characterizing the high-temperature properties of rubber-modified asphalt and the decoupling of PE / IE.

[0095] Limitation 1: Significantly underestimates the relative contribution of interaction effects in the early stages of aging.

[0096] As can be seen from Table 9, based on G The |IE| / |PE| ratio of / sinδ is consistently much lower than that based on J. nr The ratio. Taking the unaged state as an example, J nr The system exhibits a high |IE| / |PE| ratio of 3.76, clearly demonstrating the absolute dominance of the interaction effect on high-temperature performance, with the particle effect playing only a secondary role; while G In the / sinδ system, this ratio is only 0.54, and the weight of IE is actually lower than that of PE. This means that if G is used... Using / sinδ as an evaluation metric reverses the conclusion that the first-stage interaction effect dominates the improvement in high-temperature performance, incorrectly identifying the particle effect as the main contributor. The root cause of this distortion lies in G / sinδ has insufficient sensitivity to the rubber-asphalt interaction effect, G As a linear viscoelastic composite stiffness index, / sinδ cannot effectively separate the contribution of the "heavyening" of the asphalt phase caused by rubber swelling to the high-temperature performance, resulting in a systematic and significant compression of the calculated value of IE.

[0097] Limitation 2: It cannot accurately capture the elastic response of rubber.

[0098] After undergoing 20 hours of PAV aging, at a standard test temperature of 64°C, CRMA's G... / sinδ is lower than CR-A, causing PE to turn negative. Superficially, this seems to indicate that particulate effects have impaired high-temperature performance; however, the examples are based on J... nr The PE value remained negative (-0.0289) at PAV20h, and the interaction effect IE (-0.9229) continued to make a strong and beneficial contribution, indicating that the overall performance was still in the improvement range. The reason for this PE sign reversal in / sinδ is that the index fails to fully consider the influence of the delayed elastic component: the oxidative hardening of the asphalt matrix after aging leads to G Increase, G / sinδ will G The increase is directly interpreted as performance improvement, leading to an overestimation of the CR-A index; while the contribution of the elastic recovery of rubber particles in CRMA to G The failure to effectively reflect / sinδ resulted in a relatively low CRMA index. The combined effect of these two factors led to G... In the / sinδ system, PE prematurely turns negative, creating the false signal that "the particulate effect has failed." In contrast, J nr By using multi-stress level creep recovery tests, elastic recovery and non-recoverable viscous deformation are directly separated. This allows for the sensitive capture of the actual elastic recovery contribution provided by rubber particles under repeated loading, avoiding misjudgment of the PE sign due to the insensitivity of the index to the elastic response.

[0099] Limitation 3: The physical meaning is inconsistent with the multi-temperature zone index system.

[0100] In the multi-temperature zone evaluation system established in this invention, the intermediate temperature N f The S / m ratio directly characterizes fatigue life, while the low-temperature S / m ratio directly characterizes low-temperature crack resistance; both are engineering indicators that directly reflect specific service performance. High-temperature J... nr It characterizes the irreversible permanent deformation of a material after repeated loading, directly corresponding to the mechanical mechanism of pavement rutting. The three indicators have highly unified physical meanings and are all directly related to the types of pavement distress under specific temperature ranges. And G... / sinδ, as a linear viscoelastic composite parameter, reflects the composite stiffness under undamaged conditions. Its correlation with actual pavement rutting is indirect and nonlinear. If the high-temperature index is changed from J... nr Replace with G If / sinδ is used, the physical meaning of the high-temperature index will be fundamentally separated from that of the medium-temperature and low-temperature indexes, which is not conducive to forming a logically consistent unified evaluation framework.

[0101] Limitation 4: There are logical obstacles to interpreting the meaning of the changes in the symbols PE and IE.

[0102] In J nr In the system, negative PE and IE indicate performance improvement, while positive PE and IE indicate performance degradation. The sign reversal directly corresponds to the change in the nature of the effect, with a clear physical meaning. However, in G... In the / sinδ system, due to the appearance of CRMA G The inversion phenomenon where / sinδ is lower than CR-A (negative for PE) does not occur because of rubber particle failure, but rather due to G. The inherent elastic response blind zone of the / sinδ index itself renders the positive and negative signs of PE meaningless in terms of physical indication. A negative PE could indicate that the rubber particles have indeed damaged high-temperature performance (e.g., after deep aging), or it could indicate that the rubber particles still play a reinforcing role but this is masked by the index blind zone (e.g., PAV20h). This ambiguity in the meaning of the sign makes the aging stage determination criterion based on sign changes unsuitable for G... Established within the / sinδ system, this fundamentally loses the core innovative feature of this invention: stage determination based on sign reversal.

[0103] The comparison between Comparative Example 3 and the Example is summarized in Table 10.

[0104] Table 10 Comparison between Comparative Example 3 and the Examples

[0105] In summary, comparative example 3 proves that the rutting factor G / sinδ has inherent limitations in evaluating the high-temperature performance of rubber-modified asphalt due to its insufficient ability to characterize the elastic response of rubber particles and its lack of sufficient consideration of the delayed elastic component. This is manifested in the systematic distortion of the contribution weights of PE and IE, and the erroneous predictions resulting from the sign shift of PE. This invention selects J... nr As a high-temperature rheological index, it is not a simple replacement for conventional indices, but rather based on J... nr The targeted technical selection was made based on the technological advantages of being able to directly separate the elastic recovery and non-recoverable viscous deformation of materials through multi-stress level creep recovery testing, and having a higher response sensitivity to the elastic contribution of rubber particles. This selection directly ensures the accuracy of PE and IE decoupling and the reliability of aging stage determination.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of reaction of rubber asphalt, characterized in that: Includes the following steps: S1 Obtain rubber-modified asphalt samples and base asphalt of the same origin as the rubber-modified asphalt; both the rubber-modified asphalt samples and the base asphalt have multiple aging degrees, including the unaged state and different aging states after aging treatment; the aging treatment is: short-term aging at 163℃ for 85min using RTFO; or short-term aging at 163℃ for 85min using RTFO, followed by aging at 100℃ and 2.1MPa under PAV conditions for 20h~80h; S2 performs phase separation on rubber-modified asphalt samples under each aging state at a temperature greater than or equal to 155℃ and less than 180℃ to obtain asphalt phase and rubber phase. S3 conducted rheological property tests on the rubber-modified asphalt, the asphalt phase, and the matrix asphalt under preset temperature conditions of high temperature, medium temperature, and low temperature, respectively: the irreversible creep compliance J was obtained under high temperature conditions. nr The fatigue life N obtained by time scanning under medium temperature conditions was obtained. f The ratio of low-temperature creep stiffness S to creep rate m, S / m, was obtained by testing under low-temperature conditions, and the corresponding rheological performance index values ​​of the three were obtained. S4 calculates the particle effect value PE and the interaction effect value IE under each aging state according to equations (1) and (2) for each temperature domain: Equation (1); Equation (2); In the formula, Unfiltered is the rheological performance index value of the rubber-modified asphalt, Filtered is the rheological performance index value of the asphalt phase, and Neat is the rheological performance index value of the base asphalt. Among them, PE is defined as the contribution of rubber particles insoluble in the asphalt phase to the rheological properties of the system, and IE is defined as the change in intrinsic properties of the asphalt phase caused by the interaction between rubber and asphalt through material exchange and chemical reaction; the combined evolution trend of PE and IE characterizes the degree of rubber-asphalt reaction. S5 based on high temperature J nr The numerical signs and trends of the corresponding particle effect PE_H, the high-temperature interaction effect IE_H, and the low-temperature interaction effect IE_L with the degree of aging are used to divide the aging process of rubber-modified asphalt into three stages to evaluate the degree of rubber-asphalt reaction, and to determine the timing of recycling based on the divided aging stages: When IE_H<0 and IE_L>0, it is determined to be the first stage dominated by asphalt oxidation hardening and rubber swelling absorption, and no recycling treatment needs to be initiated. When IE_H<0 and IE_L<0, it is determined to be the second stage of dynamic competition between rubber degradation and asphalt aging, and the stage of recommending recycling treatment is entered. When PE_H>0 and IE_H>0, it is determined to be the third stage dominated by aging of the rubber-asphalt blend, entering the regeneration stage of restoring the overall performance of the blend. This regeneration stage indicates that the soluble rubber components have been largely depleted. The determination of the third stage also utilizes medium-temperature N... f The corresponding PE and IE are used for auxiliary verification: when the temperature is N f When the corresponding PE value decreases by more than 30% compared to the second stage, and the corresponding IE value shows a continuous increasing trend, it can be used to confirm that the rubber-asphalt reaction has entered the third stage.

2. The method for determining the timing of regeneration of aged rubber-modified asphalt according to claim 1, characterized in that: The rubber-modified asphalt sample was prepared by the following method: the base asphalt was heated to a molten state in an oven at 140℃-160℃, and then transferred to a constant temperature electric heating mantle to continue heating to 180℃-190℃. Under constant temperature conditions of 180℃-190℃, waste rubber particles accounting for 18%-22% of the asphalt mass were added while stirring. A high-speed shearing machine was used to shear at a speed of 4400r / min-4600r / min for 8min-12min. After shearing, stirring and development were continued at 180℃-190℃ for 25min-35min.

3. The method for determining the timing of regeneration of aged rubber-modified asphalt according to claim 1, characterized in that: The phase separation in S2 specifically adopts the high-temperature mesh sieve percolation method: the rubber-modified asphalt sample is placed on a 200-300 mesh standard sieve, and a collection container is set up below it. The whole sample is placed in an oven at 160±5℃ for 30±5 minutes to collect the asphalt phase.

4. The method for determining the timing of regeneration of aged rubber-modified asphalt according to claim 1, characterized in that: The S2 process also includes the separation of the rubber phase: a rubber-modified asphalt sample is weighed and dissolved in trichloroethylene, stirred at 45℃-55℃, filtered through a filter membrane under vacuum, and the retained rubber particles are dried by blowing to obtain the rubber phase.

5. The method for determining the timing of regeneration of aged rubber-modified asphalt according to claim 4, characterized in that: The drying temperature of the retained rubber particles is 40℃-60℃, and the drying time is 12h-24h.

6. The method for determining the timing of regeneration of aged rubber-modified asphalt according to claim 1, characterized in that: The high temperature in S3 is 60℃-65℃; the medium temperature is 20℃-25℃; and the low temperature is -10℃ to -20℃.

7. The method for determining the timing of regeneration of aged rubber-modified asphalt according to any one of claims 1-6, characterized in that: It also includes a multi-dimensional cross-validation step: based on the rubber phase obtained in S2, the mass m of the dried rubber phase is obtained. R 1. The initial mixing mass is m0. Calculate the solubility S = (m0 – m R ) / m0×100%; the average particle area S of the separated rubber phase R The expansion rate E is calculated based on the average area S0 of the original rubber particles. R –S 0) / S0×100%; Combining the changes in solubility S and expansion rate E with the degree of aging, cross-validation is performed with PE and IE to achieve a multi-dimensional evaluation of the degree of rubber-asphalt reaction.

8. The method for determining the timing of regeneration of aged rubber-modified asphalt according to any one of claims 1-6, characterized in that: The S5 method for determining the regeneration timing based on the degree of reaction also includes matching corresponding regeneration strategies in stages: When it is determined to be in the first stage, the swelling balance can be controlled by reserving a surplus of light components in the initial formula design or by optimizing the preparation process parameters, without the need to start a special regeneration process. When it is determined to be the second stage, a composite regeneration strategy with the core of supplementing light components and repairing the rubber crosslinking network is adopted; When the stage is determined to be the third stage, a reconstruction and regeneration strategy is adopted, which is based on chemical regeneration using the surface active sites of residual degradation products or the introduction of exogenous polymers to construct new elastic networks.

9. The method for determining the timing of regeneration of aged rubber-modified asphalt based on the degree of rubber asphalt reaction as described in any one of claims 1 to 6 is applied to the staged and precise regeneration of aged rubber-modified asphalt.

10. The application according to claim 9, characterized in that: The phased precision regeneration includes: when it is determined to be the second stage, a composite regeneration strategy of supplementing lightweight components and repairing the rubber crosslinking network is adopted; when it is determined to be the third stage, a reconstruction regeneration strategy of using the surface active sites of residual degradation products for chemical regeneration or introducing exogenous polymers to construct a new elastic network is adopted.

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