Biomimetic adhesion modified rubber asphalt and a method for preparing the same

Abstract

This invention relates to a biomimetic adhesive modified rubber asphalt and its preparation method, comprising the following steps: heating and melting base asphalt, adding rubber powder under stirring conditions to obtain a first rubber powder asphalt blend; subjecting the first rubber powder asphalt blend to a first shear treatment to obtain a second rubber powder asphalt blend; adding a biomimetic adhesive polymer to the second rubber powder asphalt blend, subjecting it to a second shear treatment to obtain a third blend; adding methyl epoxide fatty acid ester to the third blend, stirring evenly, and then subjecting it to a constant-temperature swelling and development treatment to obtain modified rubber asphalt. This invention uses a biomimetic adhesive polymer and methyl epoxide fatty acid ester as additives to improve rubber asphalt. The resulting modified rubber asphalt can balance high-temperature stability and low-temperature crack resistance; it has moderate viscosity, improving its workability; and it can alleviate the phase separation behavior of rubber asphalt, thereby improving its storage stability.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials, specifically to a biomimetic adhesive modified rubber asphalt and its preparation method. Background Technology

[0002] Most industrialized countries and regions in the world today face severe challenges and dilemmas in the disposal of automotive industry waste (such as scrap tires). The thermomechanical, chemical, and physical properties of scrap tires are suitable for asphalt pavement engineering; therefore, one method of recycling scrap tires is to process them into rubber powder for asphalt modification.

[0003] Modified asphalt made from waste rubber powder exhibits significantly optimized road performance, with substantial improvements in high-temperature rutting resistance, durability, and fatigue resistance compared to base asphalt, leading to its widespread application. The core of rubberized asphalt preparation lies in the formation of a stable viscoelastic composite system through a physical swelling process between base asphalt and waste rubber powder under high-temperature and high-speed shear conditions.

[0004] However, this preparation mechanism also determines its inherent defects in practical engineering applications: (1) Extremely high viscosity and extremely poor construction adaptability: Due to the influence of the three-dimensional elastic network structure of the composite system, the viscosity of rubber asphalt is significantly higher than that of ordinary modified asphalt. Therefore, the mixing temperature of the mixture during construction needs to be higher, usually 20-30°C higher than that of SBS modified asphalt, reaching 185-195°C, and the paving temperature ≥175°C. The production energy consumption is significantly higher than that of ordinary asphalt. At the same time, the insufficient fluidity caused by high viscosity makes the paving resistance large and the aggregate wetted unevenly during construction, which easily leads to clumping and segregation. Its construction workability (such as paving smoothness, aggregate) is affected. (1) The wetting effect is not as good as other modified asphalts; during construction, it is not only inefficient, but also causes serious equipment wear; (2) The performance balance is insufficient, its low temperature crack resistance is limited, and its storage stability is poor: the fluidity of rubber asphalt decreases under low temperature conditions, and its plastic deformation capacity is still short compared with modified asphalts such as SBS. It is difficult to fully adapt to the stress release requirements of extremely cold regions, and its low temperature crack resistance is limited. When used in extremely cold regions, it is easy to break brittlely; in addition, the rubber particles and asphalt only form a temporary stable structure through physical adsorption. It lacks strong chemical bond constraints, which directly leads to poor storage stability and easy particle sedimentation and system stratification. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a biomimetic adhesive modified rubber asphalt and its preparation method, thereby solving the technical problems of excessively high viscosity of rubber asphalt which is not conducive to construction, poor low-temperature crack resistance and poor storage stability in the prior art.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing biomimetic adhesive modified rubber asphalt, comprising the following steps: S1, heating and melting base asphalt, adding rubber powder under stirring conditions to obtain a first rubber powder asphalt blend; S2, subjecting the first rubber powder asphalt blend to a first shear treatment to obtain a second rubber powder asphalt blend; S3, adding a biomimetic adhesive polymer to the second rubber powder asphalt blend, subjecting it to a second shear treatment to obtain a third blend; S4, adding epoxy fatty acid methyl ester to the third blend, stirring evenly, and then subjecting it to a constant-temperature swelling and development treatment to obtain modified rubber asphalt.

[0007] Secondly, the present invention provides a modified rubber asphalt prepared by the above-described preparation method.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention uses biomimetic adhesive polymers and epoxy fatty acid methyl esters as additives to improve rubber asphalt. Epoxy fatty acid methyl esters play a core role in efficient plasticizing and viscosity reduction, significantly reducing the viscosity and construction temperature of rubber asphalt, and improving the fluidity and paving uniformity of the mixture. The biomimetic adhesive polymers rely on biomimetic adhesion mechanisms to strengthen the interfacial chemical bonding between rubber asphalt and aggregates, thereby improving the adhesion strength of the system. By synergistically improving the ductility of rubber asphalt, the low-temperature flexibility and crack resistance of the resulting modified rubber asphalt are optimized, compensating for its weakness of low-temperature brittle fracture. The increased penetration and decreased softening point ensure good high-temperature stability, allowing the modified asphalt to achieve a balance between high-temperature stability and low-temperature crack resistance. Simultaneously, the invention introduces biomimetic adhesive polymers and epoxy fatty acid methyl esters, resulting in a moderate viscosity of the modified rubber asphalt, improving its workability (such as mixing fluidity and paving uniformity), enhancing its performance in actual road engineering, and extending road service life. Furthermore, it alleviates the phase separation behavior of rubber asphalt, thereby improving its storage stability and achieving comprehensive optimization and enhancement of the road performance of rubber asphalt. Attached Figure Description

[0009] Figure 1 These are the penetration test results of the biomimetic adhesive modified rubber asphalt of this invention at 25°C. Figure 2 The softening point test results are those of the biomimetic adhesive modified rubber asphalt of this invention. Figure 3 The results are the 5℃ ductility test results of the biomimetic adhesive modified rubber asphalt of this invention; Figure 4 The results are the rotational viscosity test results of the biomimetic adhesive modified rubber asphalt of this invention; Figure 5 The results are the storage stability test results of the biomimetic adhesive modified rubber asphalt of this invention; Figure 6These are the pull-out strength test results of the biomimetic adhesive modified rubber asphalt of this invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0012] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0013] To address the shortcomings of current rubber asphalt, such as excessively high viscosity hindering construction, poor low-temperature crack resistance, and poor storage stability, this invention provides a biomimetic adhesive-modified rubber asphalt and its preparation method. Using a mussel-inspired biomimetic adhesive polymer and epoxy fatty acid methyl ester as additives to improve rubber asphalt, the epoxy fatty acid methyl ester exerts a highly efficient plasticizing and viscosity-reducing core effect, significantly lowering the viscosity and construction temperature of the rubber asphalt, and improving the flowability and paving uniformity of the mixture. The mussel-inspired biomimetic adhesive polymer, relying on a biomimetic adhesive mechanism, strengthens the interfacial chemical bonding between the rubber asphalt and aggregates, enhancing the system's adhesion strength and resistance to water damage. The synergistic effect of these two additives further optimizes the low-temperature flexibility and crack resistance of the rubber asphalt, compensating for its low-temperature brittle fracture weakness, significantly improving its service performance in actual road engineering, extending the service life of the pavement, and thus achieving a comprehensive optimization and improvement of the road performance of rubber asphalt.

[0014] In a first aspect, the present invention provides a method for preparing biomimetic adhesive modified rubber asphalt, comprising the following steps: S1, the base asphalt is heated and melted, and rubber powder is added under stirring conditions to obtain the first rubber powder asphalt blend; S2, the first rubber powder asphalt blend is subjected to a first shearing treatment to obtain a second rubber powder asphalt blend; S3, add a biomimetic adhesive polymer to the second rubber powder asphalt blend, and then perform a second shearing treatment to obtain the third blend; S4. Epoxy fatty acid methyl ester is added to the third blend, stirred evenly, and then subjected to constant temperature swelling and development treatment to obtain modified rubber asphalt.

[0015] This invention utilizes a mussel-inspired biomimetic adhesive polymer as one of the modifiers. Through the synergistic effect of non-covalent bonds such as multiple hydrogen bonds and π-π interactions, it can significantly enhance the interfacial bond strength between asphalt and aggregates, while also exhibiting good high and low temperature performance. Epoxy fatty acid methyl ester, as a bio-based environmentally friendly modifier, can significantly improve the low-temperature flexibility and plasticity of asphalt, and improve the workability of rubber asphalt. By externally incorporating the aforementioned biomimetic adhesive polymer and epoxy fatty acid methyl ester into the rubber asphalt system, the two can exert a synergistic effect: on the one hand, they synergistically improve ductility, thereby optimizing the low-temperature flexibility and crack resistance of the resulting modified rubber asphalt while maintaining high-temperature stability, compensating for its weakness of low-temperature brittle fracture, and balancing high and low temperature performance; on the other hand, they synergistically improve storage stability and enhance the interfacial adhesion between rubber asphalt and aggregates. Furthermore, this invention simultaneously introduces the biomimetic adhesive polymer and epoxy fatty acid methyl ester, resulting in a moderate viscosity of the modified rubber asphalt, improving its workability (such as mixing fluidity and paving uniformity), enhancing its service performance in actual road engineering, and extending the service life of the pavement.

[0016] In some embodiments, in step S1, the base bitumen is heated to 175–185°C.

[0017] In some embodiments, in step S1, the amount of rubber powder is 10 to 20% of the mass of the base asphalt.

[0018] In some embodiments, the conditions for the first shearing process in step S2 include: a temperature of 175–185°C, a rotation speed of 5000–7000 rpm, and a shearing time of 20–40 min.

[0019] In some embodiments, step S3, the preparation step of the biomimetic adhesive polymer includes: Under the action of an initiator, styrene and acrylic acid undergo a free radical copolymerization reaction to produce styrene containing carboxyl groups; A biomimetic adhesive polymer is obtained by reacting carboxyl-containing styrene with dopamine hydrochloride via an amidation reaction.

[0020] Furthermore, the initiator includes azobisisobutyronitrile, added in an amount of 0.5 to 1.5% of the mass of styrene.

[0021] Furthermore, the amount of acrylic acid added is 12-18% of the mass of styrene.

[0022] Furthermore, the conditions for the free radical copolymerization reaction include: a reaction temperature of 50–70 °C and a reaction time of 9–11 h.

[0023] Furthermore, after the free radical copolymerization reaction is completed, styrene containing carboxyl groups is obtained by washing and drying.

[0024] Further, carboxyl-containing styrene and dopamine hydrochloride are reacted via amidation to obtain a biomimetic adhesive polymer. Specifically, the reaction involves: dissolving carboxyl-containing styrene in a solvent, adding hydroxybenzotriazole and cooling to 0–4°C, adding carbodiimide salt and stirring for 20–40 min to obtain a mixture; dissolving dopamine hydrochloride in a solvent, adding triethylamine for activation treatment to obtain an activated dopamine solution; adding the activated dopamine solution to the mixture, heating to 20–30°C under a protective atmosphere and reacting for 11–13 h; after the reaction is complete, precipitation with hydrochloric acid, washing with water and drying to obtain the biomimetic adhesive polymer.

[0025] Furthermore, carbodiimide salts include EDC. HCl.

[0026] Furthermore, the molar ratio of the carboxyl group to hydroxybenzotriazole, carbodiimide salt, and dopamine hydrochloride in styrene containing carboxyl groups is 1:(0.95-1.05):(0.95-1.05):(1.1-1.3); the molar ratio of dopamine hydrochloride to triethylamine is 1:(0.95-1.05).

[0027] Furthermore, the solvents used in both the free radical copolymerization and amidation reactions include N,N-dimethylformamide.

[0028] In some embodiments, in step S3, the amount of biomimetic adhesive polymer is 0.5 to 1.5% of the mass of the base asphalt. Since the biomimetic adhesive polymer, when combined with rubber asphalt, will significantly increase the viscosity of the asphalt in the combined system, it will have a significant impact on the workability and construction properties of the resulting modified asphalt. Therefore, the amount of biomimetic adhesive polymer is controlled to be low.

[0029] In some embodiments, the conditions for the second shearing process in step S3 include: a temperature of 175–185°C, a rotation speed of 5000–7000 rpm, and a shearing time of 20–40 min.

[0030] In some embodiments, the amount of epoxy fatty acid methyl ester added is 2 to 5% of the mass of the base asphalt. Epoxy fatty acid methyl ester has a significant effect on the high-temperature stability of asphalt, and it is difficult to achieve the expected modification effect at low dosages. Therefore, its dosage cannot be too low, but excessive dosage will affect the interfacial strength. Therefore, its addition is controlled to be 2 to 5% of the mass of the base asphalt, and more preferably 2.5 to 3.5%.

[0031] In some embodiments, in step S4, the temperature of the isothermal swelling and development treatment is 175–185°C, and the time is 20–40 min.

[0032] In some embodiments, the stirring rate in steps S1 and S4 is lower than the rotational speed in the first shearing process and the second shearing process.

[0033] Secondly, the present invention provides a modified rubber asphalt prepared by the above-described preparation method.

[0034] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0035] To avoid redundancy, the following descriptions are provided for some of the raw materials.

[0036] The base asphalt used in this invention is 70# base asphalt, and its basic physical properties are shown in Table 1.

[0037] Table 1 Basic Physical Properties of 70# Base Asphalt

[0038] The rubber powder is made from waste tires that have been mechanically crushed. The particle size is controlled to be 40-80 mesh, with an ash content of ≤10% and a metal impurity content of ≤0.5%. The rubber powder is weighed according to the usage ratio and placed in an oven at 130℃ for 2 hours to remove surface moisture and volatile impurities, ensuring that the swelling effect is not affected by moisture.

[0039] The monomer raw materials required for the preparation of biomimetic adhesive polymers include styrene (St), acrylic acid (AA), dopamine hydrochloride (DA), azobisisobutyronitrile (AIBN), and anhydrous dimethylformamide (DMF). The preparation can be divided into two steps: Step 1: Free radical copolymerization of styrene (St) and acrylic acid (AA) to produce carboxyl-containing styrene: Specifically, styrene and 15% (by weight of styrene) of acrylic acid are added to a round-bottom flask, with 1% (by weight of styrene) of azobisisobutyronitrile (AIBN) as the initiator and 2-3 times (by weight of propylene oxide) of anhydrous DMF as the polar solvent. After mixing, the mixture is reacted in a 60°C water bath for 10 hours. After the reaction is complete, the mixture is repeatedly washed with n-hexane to remove the lower layer liquid, and then dried in a drying oven at 60°C for 5 hours to obtain the carboxyl-containing styrene (St-A).

[0040] Step 2: Amide reaction of carboxyl-containing styrene (St-A) with dopamine hydrochloride: Powdered carboxyl-containing styrene (St-A) is added to a three-necked flask, followed by the addition of anhydrous DMF at a mass 10 times that of the carboxyl-containing styrene, and stirring until completely dissolved. An equivalence of the carboxyl groups in St-A is then added to the flask, and the reaction system is cooled to 0°C. Subsequently, an equivalence of the carbodiimide salt (EDC) is added. The mixture was stirred at 0°C for 30 minutes to obtain a mixed solution. Then, in another flask, 1.2 equivalents of dopamine hydrochloride relative to the carboxyl group were added. The solution was dissolved in anhydrous DMF with a mass of 2-3 times that of dopamine hydrochloride, and an equivalent amount of anhydrous triethylamine was added dropwise. The mixture was activated for 10 minutes to obtain an activated dopamine solution. The activated dopamine solution was then added to the mixed solution reaction system in a three-necked flask. The temperature was raised to 25°C and the mixture was stirred for 12 hours under nitrogen protection. After the reaction was completed, the product was precipitated several times with dilute hydrochloric acid, washed with water until neutral, and dried under vacuum at 50°C to obtain a biomimetic adhesive polymer (styrene containing dopamine), denoted as StA-g-DA.

[0041] Example 1 A method for preparing biomimetic adhesive modified rubber asphalt includes the following steps: S1. The base asphalt is heated to 180°C and kept at a constant temperature to provide a stable environment for the subsequent component fusion. Then, under continuous stirring, the dried rubber powder (15% of the mass of the base asphalt) is slowly and uniformly added to the constant-temperature asphalt. Stirring is maintained during the feeding process to avoid the rubber powder from agglomerating. After all the materials are added, stirring is continued until the system forms a homogeneous suspension to obtain the first rubber powder asphalt blend. S2, the first rubber powder asphalt blend is subjected to high-speed shearing at 6000 rpm for 30 minutes under constant temperature of 180℃ to achieve preliminary dispersion and swelling of rubber powder, and the second rubber powder asphalt blend is obtained. S3, add 1% of StA-g-DA by mass of the base asphalt to the second rubber powder asphalt blend, maintain a constant temperature of 180℃ and a rotation speed of 6000rpm and continue high-speed shearing for 30min to promote the interfacial bonding of StA-g-DA with rubber powder and asphalt, and obtain the third blend. S4. After the shearing process is completed, reduce the stirring speed and add 3% epoxy fatty acid methyl ester by mass of base asphalt to the third blend. Continue stirring for 10 minutes until the mixture is uniform. Then, place it in a 180℃ oven for constant temperature swelling and development for 30 minutes to obtain the target modified rubber asphalt, denoted as StA-CR-EMF3 / MA.

[0042] Example 2 Compared with Example 1, the only difference is that the amount of epoxy fatty acid methyl ester added is adjusted to 5% of the mass of the base asphalt, and the other steps and conditions are the same as in Example 1; thus, biomimetic adhesive polymer modified rubber asphalt (StA-CR-EMF5 / MA) is obtained.

[0043] Comparative Example 1 The base bitumen used in Example 1 was used directly.

[0044] Comparative Example 2 Compared with Example 1, the only difference is that: no rubber powder and epoxy fatty acid methyl ester are added, and only biomimetic adhesive polymer is added alone. That is, all the treatment in step S2 and part of the treatment in steps S1 and S4 are removed. StA-g-DA is added to the base asphalt heated to 180°C for shear treatment and isothermal swelling development. Other steps and conditions are the same as in Example 1. Biomimetic adhesive polymer modified asphalt (abbreviated as StA-g-DA / MA) is obtained.

[0045] Comparative Example 3 Compared with Example 1, the only difference is that: no StA-g-DA and epoxy fatty acid methyl ester are added, only rubber powder is added alone, that is, all the treatment in step S3 and part of the treatment in step S4 are removed, and the second rubber powder asphalt blend is directly subjected to isothermal swelling development. Other steps and conditions are the same as in Example 1; rubber modified asphalt (CR / MA) is obtained.

[0046] Comparative Example 4 Compared with Example 1, the only difference is that epoxy fatty acid methyl ester is not added, that is, part of the treatment in step S4 is removed, and the third blend is directly subjected to isothermal swelling development. Other steps and conditions are the same as in Example 1; biomimetic adhesive polymer modified rubber asphalt (StA-CR / MA) is obtained.

[0047] Performance testing Penetration: According to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011 T 0604), the penetration of asphalt is determined under the conditions of 25℃ temperature, 100g load and 5s penetration time, and is expressed as 0.1mm.

[0048] Softening point: According to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011 T 0606), the softening point of modified asphalt is tested by the ring and ball method to evaluate its high-temperature performance.

[0049] Ductility: The ductility of modified asphalt was tested using a ductility tester according to the test method in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011 T 0605). The test temperature and tensile speed were set to 5℃ and 5cm / min, respectively.

[0050] Viscosity: According to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011 T 0625), the viscosity values ​​of modified asphalt at different temperatures (125℃, 135℃, 145℃, 155℃ and 165℃) were tested using a Brookfield rotational viscometer to evaluate its viscosity-temperature sensitivity.

[0051] Polymer-modified asphalt segregation test: According to the test method of "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2011 T 0661), softening point tests were conducted on the asphalt samples at the top and bottom of the cured asphalt pipe, and the difference in softening points was taken as the evaluation standard for the storage stability of modified asphalt.

[0052] Pull-out test: Before the experiment, square basalt specimens with a side length of 50 mm were prepared after cleaning and drying, and then heated in an oven at 160℃. After heating, molten asphalt was applied between two aggregate specimens and extruded into shape. After the specimens cooled and solidified, they were placed at a constant temperature of 20℃ for 4 hours. In the laboratory, the specimens were fixed on the MTS testing machine with screws and the test was conducted at a pull-out rate of 10 mm / min. The maximum pull-out force was measured and the interfacial pull-out strength was calculated.

[0053] This invention prepares modified rubber asphalt with both high temperature resistance and high toughness by incorporating a biomimetic adhesive polymer and epoxy fatty acid methyl ester into rubber asphalt, thereby compensating for the performance deficiencies of rubber asphalt. Performance tests were conducted on Examples 1-2 and Comparative Examples 1-4 above, and the results are as follows: Figures 1-6 As shown.

[0054] (1) Results of penetration test at 25℃ Figure 1It can be seen that different modifier compound systems have a significant impact on the penetration and workability of asphalt: when biomimetic adhesive polymer or rubber powder is added alone, the penetration of asphalt decreases to 60 and 49 respectively compared to the base asphalt, indicating a significant increase in asphalt consistency. In the compound system of rubber powder and biomimetic adhesive polymer, the penetration of asphalt further decreases to 42, and the consistency continues to increase, leading to more prominent defects in workability. However, after introducing epoxy fatty acid methyl ester into this compound system, the penetration of asphalt shows a significant upward trend. Among them, the penetration of the StA-CR-EMF3 / MA system can reach 70, which significantly improves workability and can better balance the core road performance and workability of asphalt. In contrast, the penetration of StA-CR-EMF5 / MA further increases, and its resistance to deformation is weaker than that of StA-CR-EMF3 / MA in Example 1. In summary, through comprehensive performance comparison and demonstration, StA-CR-EMF3 / MA is the optimal modifier combination scheme.

[0055] (2) Based on the softening point test results ( Figure 2 As can be seen, the softening points of asphalt in different modifier compound systems show significant differences: the softening points of the base asphalt and the single biomimetic adhesive polymer modification system are only 47.8℃ and 48.6℃, respectively; when rubber powder is added alone or when rubber powder and polymer are compounded (StA-CR / MA), the softening point of asphalt increases significantly, reaching 61.3℃ and 64.7℃, respectively. The excessively high softening point will increase the mixing and compaction temperature of asphalt, increasing the difficulty of construction and energy consumption; however, after introducing epoxy fatty acid methyl ester into the compound system, the softening point of asphalt shows a significant decrease. The softening point of the StA-CR-EMF3 / MA system is 58℃, which effectively alleviates the problem of excessively high softening point of the compound system, reduces the construction temperature requirements, and maintains a suitable softening point to ensure construction quality, avoid high-temperature deformation, and improve high-temperature stability. Therefore, after comprehensive demonstration, it was decided to adopt the StA-CR-EMF3 / MA modifier combination scheme.

[0056] (3) Based on the ductility test results at 5℃ ( Figure 3It can be seen that the ductility of the base asphalt modified with a single biomimetic adhesive polymer is only 6mm and 7mm, indicating poor low-temperature crack resistance. When rubber powder (CR / MA) is added alone or when rubber powder is compounded with a biomimetic adhesive polymer, the asphalt ductility increases to 62mm and 69mm, respectively, indicating that the addition of rubber powder can effectively improve the low-temperature ductility of asphalt, but still does not reach the ideal level for engineering applications. After introducing epoxy fatty acid methyl ester into the compound system, the asphalt ductility increases significantly. The ductility of the StA-CR-EMF3 / MA system can reach 102mm, which is about 48% higher than that of the compound system, significantly enhancing the low-temperature crack resistance of asphalt. At the same time, combined with the penetration and softening point test results, it can be seen that this system can maintain good high-temperature stability while improving low-temperature ductility, without sacrificing high-temperature performance for excessive pursuit of ductility. In contrast, the high-temperature stability of the StA-CR-EMF5 / MA system, which has the highest ductility, has decreased. In summary, through comprehensive performance comparison and demonstration, StA-CR-EMF3 / MA is the optimal modifier combination scheme that takes into account both high and low temperature performance.

[0057] (4) Based on the results of rotational viscosity test ( Figure 4 It can be seen that the viscosity of asphalt varies significantly among different modifier-modified systems: the viscosity of the base asphalt modified with a single biomimetic adhesive polymer remains at a low level; when rubber powder is added alone or in combination with the polymer, the asphalt viscosity increases significantly, especially the StA-CR / MA system, which reaches a viscosity of approximately 5.7 Pa at 135℃. Excessive viscosity leads to a significant increase in mixing and construction temperatures, increasing construction costs and energy consumption. However, the introduction of epoxy fatty acid methyl esters into this compound system resulted in a significant decrease in asphalt viscosity; specifically, the viscosity of the StA-CR-EMF3 / MA system dropped to 2.8 Pa at 135℃. This effectively alleviates the problem of excessively high viscosity in the compound system, reduces the construction temperature requirements, and maintains a suitable viscosity to ensure construction quality. The viscosity of the StA-CR-EMF5 / MA system is slightly lower than that of the StA-CR-EMF3 / MA system, which can also balance construction temperature and construction quality.

[0058] (5) Based on the results of the modified asphalt segregation test ( Figure 5 It can be seen that the addition of modifiers improves the storage stability of rubber asphalt to varying degrees. Figure 5It is known that after segregation testing, the difference in softening points between the top and bottom of CR / MA modified asphalt is as high as 9.3℃, indicating extremely poor storage stability. For the StA-CR series modified asphalts, the differences in softening points for StA-CR / MA, StA-CR-EMF3 / MA, and StA-CR-EMF5 / MA are 6.0℃, 6.5℃, and 4.55℃, respectively, which are significantly lower than those for CR / MA. Therefore, this invention, through the introduction of biomimetic adhesive polymers and epoxy fatty acid methyl esters, jointly alleviates the phase separation behavior of the CR / MA system, thereby improving its storage stability.

[0059] (6) Pull-out test results ( Figure 6 The results show that, compared to base asphalt, the addition of either StA-g-DA or rubber powder alone can significantly improve the interfacial pull-out strength. The combined addition of both exhibits a good synergistic effect, further enhancing the interfacial strength. When 3% epoxy fatty acid methyl ester (EMF) is added to the system, the interfacial strength decreases slightly, possibly due to the viscosity-reducing effect of EMF, but remains at a high level overall, especially higher than the CR / MA system. When the EMF content increases to 5%, the interfacial strength decreases further. Overall, the pull-out strength results indicate that the StA-CR-EMF3 system has superior interfacial performance.

[0060] In summary, this invention incorporates a biomimetic polymer and epoxy fatty acid methyl ester into a rubber asphalt system. On the one hand, it significantly improves the interfacial bond strength between the asphalt and aggregates while ensuring the high-temperature stability and low-temperature crack resistance of the asphalt. On the other hand, it precisely addresses the shortcomings of traditional rubber asphalt, such as high construction viscosity, insufficient mixing fluidity, and poor adaptability for paving and compaction, greatly improving the convenience and efficiency of construction operations. This composite modification technology possesses significant engineering application value, economic and social benefits, and environmental benefits. It has broad prospects for promotion and application in the construction of high-grade highways, heavy-load traffic roads, and roads in areas with large temperature differences, providing an efficient and feasible technical path for the performance upgrading and engineering application of rubber asphalt.

[0061] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing biomimetic adhesive modified rubber asphalt, characterized in that, Includes the following steps: S1, the base asphalt is heated and melted, and rubber powder is added under stirring conditions to obtain the first rubber powder asphalt blend; S2, the first rubber powder asphalt blend is subjected to a first shearing treatment to obtain a second rubber powder asphalt blend; S3, add a biomimetic adhesive polymer to the second rubber powder asphalt blend, and then perform a second shearing treatment to obtain a third blend; S4, add epoxy fatty acid methyl ester to the third blend, stir evenly, and then perform constant temperature swelling and development treatment to obtain modified rubber asphalt.

2. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 1, characterized in that, In step S1, the base asphalt is heated to 175-185°C; The amount of rubber powder is 10-20% of the mass of the base asphalt.

3. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 1, characterized in that, In step S2, the conditions for the first shearing process include: a temperature of 175–185°C, a rotation speed of 5000–7000 rpm, and a shearing time of 20–40 min.

4. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 1, characterized in that, In step S3, the preparation steps of the biomimetic adhesive polymer include: Under the action of an initiator, styrene and acrylic acid undergo a free radical copolymerization reaction to produce styrene containing carboxyl groups; The carboxyl-containing styrene is reacted with dopamine hydrochloride via an amidation reaction to obtain a biomimetic adhesive polymer.

5. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 4, characterized in that, The initiator includes azobisisobutyronitrile (AIBN), and the amount added is 0.5% to 1.5% of the mass of styrene. The amount of acrylic acid added is 12-18% of the mass of styrene; The conditions for the free radical copolymerization reaction include: a reaction temperature of 50–70°C and a reaction time of 9–11 h.

6. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 4, characterized in that, The carboxyl-containing styrene is reacted with dopamine hydrochloride via an amidation reaction to obtain a biomimetic adhesive polymer, specifically comprising: Carboxyl-containing styrene is mixed and dissolved with a solvent, hydroxybenzotriazole is added and the temperature is lowered to 0-4℃, carbodiimide salt is added and stirred for 20-40 min to obtain a mixture; Dopamine hydrochloride was dissolved in a solvent and then activated with triethylamine to obtain an activated dopamine solution. Dopamine activating solution was added to the mixture, and the mixture was heated to 20-30°C and reacted for 11-13 hours under a protective atmosphere. After the reaction was completed, the mixture was precipitated with hydrochloric acid, washed with water and dried to obtain a biomimetic adhesive polymer.

7. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 6, characterized in that, The carbodiimide salt includes EDC. HCl; The molar ratio of the carboxyl group to hydroxybenzotriazole, carbodiimide salt, and dopamine hydrochloride in the carboxyl-containing styrene is 1:(0.95-1.05):(0.95-1.05):(1.1-1.3). The molar ratio of dopamine hydrochloride to triethylamine is 1:(0.95-1.05).

8. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 1, characterized in that, In step S3, the amount of the biomimetic adhesive polymer is 0.5% to 1.5% of the mass of the base asphalt; The conditions for the second shearing process include: a temperature of 175–185°C, a rotation speed of 5000–7000 rpm, and a shearing time of 20–40 min.

9. The method for preparing biomimetic adhesive modified rubber asphalt according to claim 1, characterized in that, In step S4, the amount of epoxy fatty acid methyl ester added is 2-5% of the mass of the base asphalt; The isothermal swelling and development treatment is performed at a temperature of 175–185°C for 20–40 minutes.

10. Modified rubber asphalt prepared by any one of claims 1-9.

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