A recycled asphalt mixture doped with natural asphalt and a method for preparing the same

Abstract

This application relates to the field of recycled asphalt technology, specifically disclosing a recycled asphalt mixture mixed with natural asphalt and its preparation method. The recycled asphalt mixture mixed with natural asphalt comprises the following raw materials: 75-85 parts activated waste asphalt mixture, 5-10 parts natural rock asphalt, 5-10 parts matrix asphalt, 2-4 parts recycling agent, 1-3 parts boron-modified organic vermiculite intercalation anchoring agent, 3-5 parts rubber powder, 12-18 parts basalt crushed stone, 1-5 parts basalt fiber, 6-12 parts limestone mineral powder, and 0.5-1.2 parts crosslinking agent; the activated waste asphalt mixture is obtained by microwave irradiation and plasma etching treatment of waste asphalt. The recycled asphalt mixture of this application exhibits excellent high-temperature stability and effectively suppresses rutting and shoving defects present in recycled asphalt mixtures.

Description

Technical Field

[0001] This application relates to the field of recycled asphalt technology, and more specifically, to a recycled asphalt mixture mixed with natural asphalt and a method for preparing the same. Background Technology

[0002] Asphalt is a dark brown, viscous cementitious material composed of various high-molecular hydrocarbons and their derivatives. It possesses excellent adhesion, plasticity, water resistance, and corrosion resistance, making it an indispensable core material in road construction. It is widely used in the paving of infrastructure such as highways, municipal roads, and airport runways. Asphalt mixtures are composite materials formed by uniformly mixing asphalt as a binder with mineral aggregates of a certain gradation at a suitable temperature. Their comprehensive performance directly determines the load-bearing capacity, driving comfort, and service life of road surfaces, making them a major component of modern road pavement structures.

[0003] As highways age, large quantities of waste asphalt pavement face excavation and reconstruction, generating substantial amounts of waste asphalt mixtures. Traditional disposal methods primarily involve stockpiling and landfilling, which not only results in significant waste of asphalt and aggregate resources but also pollutes the surrounding environment. Against this backdrop, recycled asphalt mixture technology has seen extensive research and application. This technology involves crushing and screening waste asphalt mixtures, then mixing them with appropriate amounts of new asphalt, recycling agents, and new aggregates through a specific process. This effectively achieves the recycling of waste materials, reduces construction costs, and decreases reliance on natural resource extraction and asphalt imports, making it an important development direction in the road construction sector. In related technologies, such as the patent application document with publication number CN118978812A, a recycled asphalt mixture and its preparation method are disclosed. The above technical solution first treats polypropylene fibers in a mixed acid solution of sulfuric acid and nitric acid to improve the chemical activity of polypropylene fibers, enabling them to better combine with subsequent hydrotalcite-like materials. Then, a layered bimetallic hydrotalcite-like compound is generated on the surface of the pretreated polypropylene fibers. Introducing zinc-aluminum hydrotalcite-like materials into the recycled asphalt mixture can improve the heat aging resistance of the recycled asphalt. Then, through the addition reaction between double bonds, polymer polymer chains are introduced, increasing the compatibility between the composite modified polypropylene fibers and recycled asphalt. Sodium 3-allyloxy-2-hydroxy-1-propanesulfonate and p-trifluoromethylstyrene interact to jointly improve the low-temperature crack resistance and heat aging resistance of the recycled asphalt mixture.

[0004] However, existing recycled asphalt mixtures still have significant drawbacks in practical applications. In high-temperature summer conditions, recycled asphalt pavements are prone to rutting and shoving, severely impacting road performance and service life, thus hindering their widespread application in high-grade highways. This problem mainly arises because waste asphalt undergoes irreversible aging during long-term service due to natural factors such as sunlight, temperature changes, and rainwater erosion. This leads to an imbalance in asphalt components, with increased asphaltene content and decreased resin content. Consequently, the recycled asphalt exhibits insufficient high-temperature viscosity, excessive rigidity but insufficient toughness, making it prone to plastic deformation at high temperatures. Therefore, existing recycled asphalt mixtures suffer from insufficient high-temperature stability. Summary of the Invention

[0005] To enhance the high-temperature stability of recycled asphalt mixtures, this application provides a recycled asphalt mixture mixed with natural asphalt and its preparation method.

[0006] The technical solution for a recycled asphalt mixture mixed with natural asphalt provided in this application is as follows: A recycled asphalt mixture containing natural asphalt comprises the following raw materials in parts by weight: The mixture consists of 75-85 parts activated waste asphalt mixture, 5-10 parts natural rock asphalt, 5-10 parts matrix asphalt, 2-4 parts recycling agent, 1-3 parts boron-modified organic vermiculite intercalation anchoring agent, 3-5 parts rubber powder, 12-18 parts basalt crushed stone, 1-5 parts basalt fiber, 6-12 parts limestone mineral powder, and 0.5-1.2 parts crosslinking agent. The activated waste asphalt mixture is obtained by treating waste asphalt with microwave irradiation and plasma etching. The boron-modified organic vermiculite intercalation anchoring agent is obtained by organic intercalation of vermiculite powder and then modification with boric acid powder.

[0007] By adopting the above technical solution, a synergistic reinforcement system of "interface activation - molecular regeneration - covalent anchoring - skeleton reinforcement" was constructed by introducing a step-by-step activation of waste asphalt mixture and boron-modified organic vermiculite intercalation anchoring agent. This fundamentally solves the core defects of recycled asphalt mixture, such as insufficient high-temperature stability and susceptibility to rutting and shoving in summer. First, through step-by-step synergistic activation using microwave-solvent directional desorption and argon plasma deep etching, a progressive approach from macroscopic surface peeling to microscopic interface modification was achieved: microwave irradiation, through thermal and non-thermal effects, promotes the rapid evaporation of water and lightweight components adsorbed inside the waste asphalt. Combined with the penetration of saturated water vapor, it effectively peels off the dense oxidized hard shell on the surface of aged asphalt, providing a clean substrate for subsequent processing. Then, argon plasma, through high-energy particle bombardment, precisely etches the residual inert oxide layer, breaks the disordered cross-linking structure of asphalt macromolecules, and introduces active sites such as hydroxyl and carboxyl groups at the asphalt-aggregate interface, significantly improving surface energy and chemical reactivity. This activation process completely breaks through the limitations of traditional methods that rely solely on physical crushing, opening molecular channels for the penetration of rejuvenating agents and subsequent anchoring reactions. It fundamentally solves the industry pain points of rejuvenating agents being difficult to penetrate, poor integration of new and old asphalt, and weak interfacial bonding.

[0008] Furthermore, the precise selection of regenerators enables molecular-level targeted regeneration, avoiding the risk of high-temperature performance degradation caused by traditional regenerators. 1-Butyl-3-methylimidazolium thiocyanate ionic liquid or cycloalkane aromatic regenerators can selectively depolymerize over-crosslinked asphaltene or replenish missing aromatic components. While restoring the colloidal balance and rheological properties of asphalt, they avoid the introduction of large amounts of light oils, thus not reducing the high-temperature viscosity and rigidity of the asphalt. Combined with the synergistic effect of rubber powder, crosslinking agents, and basalt fibers, the rubber powder forms a crosslinked network with the asphalt under the action of the crosslinking agent, improving high-temperature elasticity and resilience. The basalt fibers and natural rock asphalt strengthen the overall skeletal structure of the mixture from the perspectives of fiber reinforcement and rigid filling, respectively. Through the synergistic effect of these components, the problem of insufficient high-temperature stability of recycled asphalt mixtures is effectively solved.

[0009] Optionally, the activated waste asphalt mixture is prepared using the following method: A1. The waste asphalt is crushed and screened to an average particle size of 10-20mm, and then placed in a closed microwave reaction chamber. It is irradiated with microwave at a frequency of 2.2-2.5GHz and a power of 350-450W for 8-12 minutes. Saturated water vapor is introduced simultaneously with the irradiation. After the irradiation is completed, the desorbed and activated waste asphalt mixture is obtained. A2. Transfer the desorbed and activated waste asphalt mixture into a plasma treatment device, introduce high-purity argon gas, and perform plasma etching treatment for 6-10 minutes at a discharge power of 120-160W and a treatment temperature of 45-60℃. After the etching treatment is completed, spray 0.5%-1.5% of the mass of the silane coupling agent solution, stir for 5-10 minutes, and then vacuum dry at 60-80℃ to obtain the activated waste asphalt mixture.

[0010] By adopting the above technical solutions, the preparation method of activated waste asphalt mixtures is defined, ensuring the feasibility of step-by-step activation and the scientific nature of the process parameters. The frequency, power, and time parameters of microwave irradiation, combined with the introduction of saturated water vapor, effectively desorb the oxide layer on the surface of the waste asphalt, avoiding aggregate damage caused by overheating. The power, temperature, and time parameters of plasma treatment precisely control the etching depth and the generation density of active sites, ensuring the uniformity and stability of interface activation. The spraying of the silane coupling agent solution and the vacuum drying steps further promote the chemical bonding between the activated interface and subsequent components, improving the overall structural durability.

[0011] Optionally, the regenerant is one of 1-butyl-3-methylimidazolium thiocyanate ionic liquid or cycloalkane aromatic regenerant.

[0012] By adopting the above technical solutions, the regenerator ensures the targeting and efficiency of the regeneration process. The strong polarity and selective depolymerization ability of ionic liquids, or the component matching of cycloalkane aromatic regenerators, can effectively repair the colloidal structure of aged asphalt and restore its viscoelasticity. At the same time, it avoids the high-temperature softening problem caused by excessive lightweight components in traditional regenerators, thus providing a basic guarantee for high-temperature stability.

[0013] Optionally, the boron-modified organic vermiculite intercalation anchoring agent is prepared by the following method: B1. Disperse vermiculite powder in an ethanol solution, add hexadecyltrimethylammonium bromide, stir at a constant temperature of 70-80℃ for 3-4 hours, filter and wash until no bromide ions are detected, and dry at 90-100℃ to obtain organic intercalated vermiculite; B2. Mix organic intercalated vermiculite with boric acid powder, place in a muffle furnace, heat to 180-220℃ at 5℃ / min, calcine in a constant temperature solid phase for 1-2 hours, and then cool naturally. Grind the calcined product into powder using an air jet mill and pass it through a 200-mesh sieve to obtain boron-modified organic vermiculite intercalation anchoring agent.

[0014] By employing the above technical solution, the preparation method of boron-modified organic vermiculite intercalation anchoring agent is limited, ensuring the synergistic achievement of its intercalation effect and high-temperature stability. The organic intercalation effect of hexadecyltrimethylammonium bromide expands the interlayer spacing of vermiculite, improving its dispersibility in asphalt; the solid-phase calcination modification of boric acid introduces high-temperature resistant BO bonds, endowing the filler with high-temperature stability. The air jet milling and sieving steps ensure the fineness and uniformity of the filler, facilitating the formation of a continuous anchoring network in the mixture.

[0015] Optionally, in step B1, the mass concentration of the ethanol solution is 60%-70%; the mass ratio of the vermiculite powder to the ethanol solution is 1:(8-10).

[0016] Optionally, in step B1, the mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide is (4-5):1.

[0017] By employing the above technical solution and limiting the mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide, the saturation of organic intercalation and the interlayer spacing are maximized. The intercalating agent can fully cover the vermiculite surface and penetrate into the interlayer, effectively weakening the interlayer forces and providing a structural basis for subsequent boron modification and bitumen penetration.

[0018] Optionally, in step B2, the mass ratio of organic intercalated vermiculite to boric acid powder is (8-10):1.

[0019] Optionally, the length of the basalt fiber is 4-8 mm.

[0020] Optionally, the crosslinking agent comprises sulfur and zinc oxide in a mass ratio of (2-3):1.

[0021] By adopting the above technical solution, a highly efficient vulcanization system is provided, which promotes the cross-linking reaction between rubber powder and asphalt. The synergistic effect of sulfur and zinc oxide can effectively form a stable cross-linking network, improve the high-temperature elasticity and resilience of asphalt, and at the same time avoid the increased brittleness caused by over-vulcanization.

[0022] This application also provides a method for preparing recycled asphalt mixtures mixed with natural asphalt, using the following technical solution: A method for preparing recycled asphalt mixture mixed with natural asphalt includes the following steps: Activated waste asphalt mixture, basalt crushed stone, and limestone mineral powder are mixed and stirred at 110-120℃ for 3-5 minutes. Then, a recycling agent and base asphalt are added and stirred at 120-150℃ for 18-22 minutes. Next, rubber powder and crosslinking agent are added and stirred at 140-145℃ for 8-10 minutes. Finally, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are added and stirred at 138-142℃ for 10-14 minutes. After cooling, a recycled asphalt mixture mixed with natural asphalt is obtained.

[0023] By adopting the above technical solution and limiting the preparation steps and temperature parameters, the orderly addition of each component and the precise control of reaction conditions are ensured. Staged stirring and temperature control ensure that the activated waste asphalt mixture, aggregates, recycling agent, base asphalt, rubber powder, crosslinking agent, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are sequentially and uniformly dispersed and undergo the expected reaction, avoiding mutual interference between components and ensuring the structural uniformity and performance stability of the final mixture.

[0024] In summary, this application has the following beneficial effects: 1. This application utilizes a step-by-step synergistic activation process combining microwave directional desorption and plasma etching to solve the problems of weak interfacial bonding and easy deformation at high temperatures in traditional recycled asphalt mixtures caused by the dense oxide layer on the surface of waste asphalt and the difficulty in penetrating the rejuvenator. Microwave irradiation utilizes thermal and non-thermal effects, combined with the penetration of saturated water vapor, to rapidly peel off the hard oxide shell on the surface of aged asphalt, exposing internal active sites. Argon plasma further removes the residual inert layer through high-energy particle etching, introducing polar groups such as hydroxyl and carboxyl groups at the asphalt-aggregate interface, significantly increasing surface energy. This process achieves step-by-step deep activation from macro to micro, providing penetration channels for the rejuvenator. Simultaneously, silane coupling agents form covalent bonds with active sites, achieving chemical bonding between new and old asphalt. This technology significantly enhances the adhesion of the asphalt-aggregate interface in recycled asphalt mixtures, improves shear resistance at high temperatures, effectively suppresses rutting and shoving damage, and provides a fundamental guarantee for the high-temperature stability of recycled asphalt mixtures.

[0025] 2. This application employs a boron-modified organic vermiculite intercalation anchoring agent. Through organic intercalation, the interlayer spacing of the vermiculite is expanded. Combined with high-temperature solid-phase modification with boric acid, high-temperature resistant BO covalent bonds are introduced, overcoming the shortcomings of conventional mineral fillers that rely solely on physical filling and are prone to failure at high temperatures. In asphalt mixtures, the boron-modified vermiculite flakes are uniformly dispersed, and boron atoms form covalent cross-links with the polar groups of activated asphalt and the aggregate surface, constructing a three-dimensional heat-resistant network. This network directly constrains the creep of asphalt molecules through chemical bonding forces, hindering aggregate particle slippage and maintaining structural stability of the mixture under high-temperature loads, effectively solving the problem of pavement plastic deformation in high-temperature summer environments.

[0026] 3. This application uses 1-butyl-3-methylimidazolium thiocyanate ionic liquid or cycloalkane aromatic group-type regenerator, overcoming the limitation of traditional regenerators that rely on light oil components, leading to high-temperature performance degradation. The ionic liquid selectively depolymerizes over-crosslinked asphaltene macromolecules through strong polarity, while the cycloalkane aromatic group replenishes the missing resins and aromatic components; both can precisely restore the colloidal structural balance of asphalt. This regenerator, while repairing the viscoelasticity of aged asphalt, avoids reducing the high-temperature viscosity of asphalt due to excessive light components, achieving a synergistic improvement in molecular-level regeneration and high-temperature stability. Detailed Implementation

[0027] The present application will be further described in detail below with reference to the embodiments.

[0028] Example of preparation of activated waste asphalt mixture Preparation Example 1 Activated waste asphalt mixture is prepared using the following method: A1. Waste asphalt is crushed and screened to obtain mixed particles with an average particle size of 10mm. These particles are then placed in a sealed microwave reaction chamber. The microwave frequency is set to 2.2GHz and the power to 350W. The mixture is then irradiated with microwave for 8 minutes. Saturated water vapor is introduced simultaneously during the irradiation process. After the irradiation is completed, the material is removed to obtain desorbed and activated waste asphalt mixture.

[0029] A2. The desorbed and activated waste asphalt mixture is transferred into a plasma treatment device. High-purity argon gas is introduced into the device, and the discharge power is adjusted to 120W and the treatment temperature is 45℃. The mixture is subjected to plasma etching treatment for 6 minutes. After the etching treatment is completed, 0.5% of KH-570 silane coupling agent solution by mass is sprayed onto the surface of the mixture and stirred at a uniform speed for 5 minutes. After stirring, the mixture is placed in a vacuum dryer at 60℃. After drying, the activated waste asphalt mixture is obtained.

[0030] Preparation Example 2 Activated waste asphalt mixture is prepared using the following method: A1. Waste asphalt is crushed and screened to obtain mixed particles with an average particle size of 15mm. These particles are then placed in a sealed microwave reaction chamber. The microwave frequency is set to 2.35GHz and the power to 400W. The mixture is then irradiated with microwave for 10 minutes. Saturated water vapor is introduced simultaneously during the irradiation process. After the irradiation is completed, the material is removed to obtain desorbed and activated waste asphalt mixture.

[0031] A2. The above-mentioned desorbed and activated waste asphalt mixture is transferred into a plasma treatment device. High-purity argon gas is introduced into the device, and the discharge power is adjusted to 140W and the treatment temperature is 52℃. The mixture is subjected to plasma etching treatment for 8 minutes. After the etching treatment is completed, KH-570 silane coupling agent solution accounting for 1.0% of its mass is sprayed onto the surface of the mixture and stirred at a uniform speed for 7 minutes. After stirring is completed, the mixture is placed in a vacuum drying condition at 70℃. After drying, activated waste asphalt mixture is obtained.

[0032] Preparation Example 3 Activated waste asphalt mixture is prepared using the following method: A1. Waste asphalt is crushed and screened to obtain mixed particles with an average particle size of 20mm. These particles are then placed in a sealed microwave reaction chamber. The microwave frequency is set to 2.5GHz and the power to 450W. The mixture is then irradiated with microwave for 12 minutes. Saturated water vapor is introduced simultaneously during the irradiation process. After the irradiation is completed, the material is removed to obtain desorbed and activated waste asphalt mixture.

[0033] A2. The above-mentioned desorbed and activated waste asphalt mixture is transferred into a plasma treatment device. High-purity argon gas is introduced into the device, and the discharge power is adjusted to 160W and the treatment temperature is 60℃. The mixture is subjected to plasma etching treatment for 10 minutes. After the etching treatment is completed, KH-570 silane coupling agent solution accounting for 1.5% of its mass is sprayed onto the surface of the mixture and stirred at a uniform speed for 10 minutes. After stirring, the mixture is placed in a vacuum drying condition at 80℃. After drying, activated waste asphalt mixture is obtained.

[0034] Preparation Example 4 The difference between the activated waste asphalt mixture and the preparation example 3 is that the KH-570 silane coupling agent solution was not sprayed after the etching and activation were completed.

[0035] Example of preparation of boron-modified organic vermiculite intercalation anchoring agent Preparation Example 5 Boron-modified organic vermiculite intercalation anchoring agent was prepared using the following method: B1. Take vermiculite powder and disperse it in a 60% ethanol solution with a mass ratio of vermiculite powder to ethanol solution of 1:8. Add hexadecyltrimethylammonium bromide to the mixed solution with a mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide of 4:1. Adjust the temperature to 70℃ and stir at a constant temperature for 3 hours. After stirring, filter the mixture and wash the filter residue repeatedly with deionized water until no bromide ions are detected in the washing liquid. Dry the washed filter residue at 90℃. After drying, organic intercalated vermiculite is obtained.

[0036] B2. Take the above-mentioned organic intercalated vermiculite and boric acid powder, mix them evenly at a mass ratio of 8:1, place the mixture in a muffle furnace, heat it to 180°C at a heating rate of 5°C per minute, and calcine it in a constant temperature for 1 hour. After calcination, turn off the muffle furnace and let the material cool naturally to room temperature. Send the cooled calcined product into an air jet mill for pulverization. After pulverization, pass it through a 200-mesh sieve and sieve out the material to obtain the boron-modified organic vermiculite intercalation anchoring agent.

[0037] Preparation Example 6 Boron-modified organic vermiculite intercalation anchoring agent was prepared using the following method: B1. Take vermiculite powder and disperse it in a 65% ethanol solution with a mass ratio of vermiculite powder to ethanol solution of 1:9. Add hexadecyltrimethylammonium bromide to the mixed solution with a mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide of 4.5:1. Adjust the temperature to 75℃ and stir at a constant temperature for 3.5 hours. After stirring, filter the mixture and wash the filter residue repeatedly with deionized water until no bromide ions are detected in the washing liquid. Dry the washed filter residue at 95℃. After drying, organic intercalated vermiculite is obtained.

[0038] B2. Take the above-mentioned organic intercalated vermiculite and boric acid powder, mix them evenly at a mass ratio of 9:1, place the mixture in a muffle furnace, heat it to 200°C at a heating rate of 5°C per minute, and calcine it in a constant temperature solid phase for 1.5 hours. After calcination, turn off the muffle furnace and let the material cool naturally to room temperature. Send the cooled calcined product into an air jet mill for pulverization. After pulverization, pass it through a 200-mesh sieve and sieve out the material to obtain boron-modified organic vermiculite intercalation anchoring agent.

[0039] Preparation Example 7 Boron-modified organic vermiculite intercalation anchoring agent was prepared using the following method: B1. Take vermiculite powder and disperse it in a 70% ethanol solution with a mass ratio of vermiculite powder to ethanol solution of 1:10. Add hexadecyltrimethylammonium bromide to the mixed solution with a mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide of 5:1. Adjust the temperature to 80℃ and stir at a constant temperature for 4 hours. After stirring, filter the mixture and wash the filter residue repeatedly with deionized water until no bromide ions are detected in the washing liquid. Place the washed filter residue at 100℃ to dry. After drying, organic intercalated vermiculite is obtained.

[0040] B2. Take the above-mentioned organic intercalated vermiculite and boric acid powder, mix them evenly at a mass ratio of 10:1, place the mixture in a muffle furnace, heat it to 220°C at a heating rate of 5°C per minute, and calcine it in a constant temperature for 2 hours. After calcination, turn off the muffle furnace and let the material cool naturally to room temperature. Send the cooled calcined product into an air jet mill for crushing. After crushing, pass it through a 200-mesh sieve and sieve out the material to obtain the boron-modified organic vermiculite intercalation anchoring agent.

[0041] Example Example 1 A recycled asphalt mixture mixed with natural asphalt, the raw material composition and proportions of which are shown in Table 1, wherein the activated waste asphalt mixture is the activated waste asphalt mixture prepared in Preparation Example 1, the base asphalt is 70# base asphalt, the recycling agent is 1-butyl-3-methylimidazolium thiocyanate ionic liquid, the boron-modified organic vermiculite intercalation anchoring agent is the boron-modified organic vermiculite intercalation anchoring agent prepared in Preparation Example 5, the basalt fiber length is 4 mm, and the crosslinking agent is a compound of sulfur and zinc oxide with a mass ratio of 2:1.

[0042] A method for preparing recycled asphalt mixture mixed with natural asphalt includes the following steps: Activated waste asphalt mixture, basalt crushed stone, and limestone mineral powder are mixed and stirred at 110°C for 3 minutes. Then, a recycling agent and base asphalt are added and stirred at 120°C for 18 minutes. Next, rubber powder and crosslinking agent are added and stirred at 140°C for 8 minutes. Finally, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are added and stirred at 138°C for 10 minutes. After cooling, a recycled asphalt mixture mixed with natural asphalt is obtained.

[0043] Example 2 A recycled asphalt mixture mixed with natural asphalt, the raw material composition and proportions of which are shown in Table 1, wherein the activated waste asphalt mixture is the activated waste asphalt mixture prepared in Preparation Example 2, the base asphalt is 70# base asphalt, the recycling agent is RA25 hot-mix asphalt recycling agent (the main component is naphthenic aromatic hydrocarbon), the boron modified organic vermiculite intercalation anchoring agent is the boron modified organic vermiculite intercalation anchoring agent prepared in Preparation Example 6, the basalt fiber length is 6 mm, and the crosslinking agent is a compound of sulfur and zinc oxide with a mass ratio of 2.5:1.

[0044] A method for preparing recycled asphalt mixture mixed with natural asphalt includes the following steps: Activated waste asphalt mixture, basalt crushed stone, and limestone mineral powder are mixed and stirred at 115℃ for 4 minutes. Then, a recycling agent and base asphalt are added and stirred at 135℃ for 20 minutes. Next, rubber powder and crosslinking agent are added and stirred at 142℃ for 9 minutes. Finally, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are added and stirred at 140℃ for 12 minutes. After cooling, a recycled asphalt mixture mixed with natural asphalt is obtained.

[0045] Example 3 A recycled asphalt mixture mixed with natural asphalt, the raw material composition and proportions of which are shown in Table 1, wherein the activated waste asphalt mixture is the activated waste asphalt mixture prepared in Preparation Example 3, the base asphalt is 70# base asphalt, the recycling agent is 1-butyl-3-methylimidazolium thiocyanate ionic liquid, the boron-modified organic vermiculite intercalation anchoring agent is the boron-modified organic vermiculite intercalation anchoring agent prepared in Preparation Example 7, the basalt fiber length is 8 mm, and the crosslinking agent is a compound of sulfur and zinc oxide with a mass ratio of 3:1.

[0046] A method for preparing recycled asphalt mixture mixed with natural asphalt includes the following steps: Activated waste asphalt mixture, basalt crushed stone, and limestone mineral powder are mixed and stirred at 120°C for 5 minutes. Then, a recycling agent and base asphalt are added and stirred at 135°C for 22 minutes. Next, rubber powder and crosslinking agent are added and stirred at 145°C for 10 minutes. Finally, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are added and stirred at 142°C for 14 minutes. After cooling, a recycled asphalt mixture mixed with natural asphalt is obtained.

[0047] Table 1. Raw material composition and proportions (kg) of recycled asphalt mixtures in Examples 1-3

[0048] Example 4 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that the activated waste asphalt mixture in this example is the activated waste asphalt mixture prepared in Preparation Example 2.

[0049] Example 5 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that the activated waste asphalt mixture in this example is the activated waste asphalt mixture prepared in Preparation Example 1.

[0050] Example 6 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that the boron-modified organic vermiculite intercalation anchoring agent used in this example is the boron-modified organic vermiculite intercalation anchoring agent prepared in Preparation Example 6.

[0051] Example 7 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that the boron-modified organic vermiculite intercalation anchoring agent used in this example is the boron-modified organic vermiculite intercalation anchoring agent prepared in Preparation Example 5.

[0052] Comparative Example Comparative Example 1 A recycled asphalt mixture was prepared according to Example 1 in the patent application document with publication number CN118978812A entitled "A Recycled Asphalt Mixture and its Preparation Method".

[0053] Comparative Example 2 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that an equal amount of untreated waste asphalt mixture is used instead of activated waste asphalt mixture in this comparative example.

[0054] Comparative Example 3 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that an equal amount of vermiculite powder is used instead of boron-modified organic vermiculite intercalation anchoring agent in this comparative example.

[0055] Comparative Example 4 A recycled asphalt mixture mixed with natural asphalt differs from Example 3 in that the activated waste asphalt mixture in this comparative example is the activated waste asphalt mixture prepared in Preparation Example 4.

[0056] Performance testing Test items: (1) Dynamic stability (DS) test at 60℃ The test was conducted according to method T0719-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). Recycled asphalt mixtures prepared in the examples and comparative examples were made into specimens of 300mm × 300mm × 50mm and placed in a constant temperature environment of 60℃ for 4 hours. A rutting tester was used, applying a constant load of 0.7MPa and compacting the mixture at a frequency of 42 times / min. The rutting depth was recorded at 1000 and 2000 compactions, and the dynamic stability (unit: times / mm) was calculated. A higher dynamic stability value indicates stronger high-temperature rutting resistance and better high-temperature stability of the mixture.

[0057] (2) High-temperature shear strength test at 70℃ The test was conducted according to method T0737-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The mixture was prepared into specimens of 50mm × 50mm × 20mm and placed in a 70℃ constant temperature chamber for 2 hours. A universal testing machine was used to conduct shear tests at a loading rate of 1mm / min. The maximum load at which the specimen failed under shear was recorded, and the shear strength (unit: MPa) was calculated. A higher shear strength indicates stronger shear resistance of the mixture at high temperatures, effectively inhibiting shoving disease.

[0058] (3) Dynamic stability test at 60°C after aging in a rotary film oven (RTFOT) The test was conducted according to method T0719-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The mixture specimens prepared in the examples and comparative examples were placed in a rotating thin-film oven and aged at 163℃ for 75 minutes. After aging, the dynamic stability of the aged specimens was measured according to the "60℃ Dynamic Stability Test" method. The ratio of the dynamic stability after aging to that before aging (retention rate) was calculated. A higher retention rate indicates a smaller decrease in high-temperature stability and better durability after long-term high-temperature aging.

[0059] Test results are shown in Table 2.

[0060] Table 2 Detection Results

[0061] The test results show that the high-temperature stability of the recycled asphalt mixture prepared in this application is significantly better than that of the comparative examples. The dynamic stability of the mixture specimens in Examples 1-7 at 60℃ is above 3120 cycles / mm, and the shear strength at 70℃ is above 1.82 MPa. In contrast, the corresponding values ​​of the comparative examples are significantly lower. Among them, the dynamic stability at 60℃ of Comparative Example 2 is only 1520 cycles / mm, and the shear strength at 70℃ is only 0.98 MPa, which is far lower than the level of the examples. The core reason for this difference is that the examples adopted a step-by-step synergistic activation process of microwave irradiation and plasma etching, which effectively peeled off the oxidized hard shell on the surface of waste asphalt and introduced a large number of active sites. At the same time, the boron-modified organic vermiculite intercalation anchoring agent constructed a three-dimensional heat-resistant network, constrained the creep of asphalt molecules, and hindered the slippage of aggregate particles, thereby significantly improving the high-temperature rutting resistance and shear resistance of the mixture.

[0062] Example 3 exhibited the highest dynamic stability at 60°C and shear strength at 70°C, at 3890 cycles / mm and 2.28 MPa, respectively. Example 1 showed relatively lower performance, while Example 2 fell between the two. This is because the boron-modified organic vermiculite intercalation anchoring agent used in Example 3 had superior microwave and plasma activation parameters, resulting in a more thorough modification effect of the anchoring agent.

[0063] The test data on long-term thermal aging performance further highlights the advantages of the technical solution of this application. The dynamic stability retention rate after aging of Examples 1 to 7 is all above 88.6%, and Example 3 reaches 93.7%, while the retention rate of each comparative example is below 83%, and that of Comparative Example 2 is only 68.3%. This is because the boron-modified organic vermiculite intercalation anchoring agent introduces high-temperature resistant BO covalent bonds after boric acid solid-phase calcination modification, which can effectively inhibit the decay of high-temperature stability of the mixture during long-term high-temperature aging. In contrast, Comparative Example 3 uses unmodified vermiculite powder, which can only play a physical filling role and cannot form a stable heat-resistant network. Its performance decays significantly after aging, demonstrating the innovation and necessity of the anchoring agent modification process of this application.

[0064] The performance shortcomings of each comparative example further confirm the importance of the core technical features of this application. Comparative Example 1, prepared using existing technology, lacks a step-by-step activation process and boron-modified anchoring agent, resulting in poor high-temperature stability and anti-aging performance. Comparative Example 2, untreated waste asphalt, has a dense surface oxide layer, making it difficult for the recycling agent to penetrate, resulting in weak interfacial bonding and the worst high-temperature performance. Comparative Example 4, without the addition of a silane coupling agent, cannot achieve effective covalent bond bridging between the activated interface and each component, resulting in insufficient interfacial bonding and a significant decrease in high-temperature performance and anti-aging performance compared to the examples.

[0065] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A recycled asphalt mixture mixed with natural asphalt, characterized in that, The raw materials include the following parts by weight: The mixture consists of 75-85 parts activated waste asphalt mixture, 5-10 parts natural rock asphalt, 5-10 parts matrix asphalt, 2-4 parts recycling agent, 1-3 parts boron-modified organic vermiculite intercalation anchoring agent, 3-5 parts rubber powder, 12-18 parts basalt crushed stone, 1-5 parts basalt fiber, 6-12 parts limestone mineral powder, and 0.5-1.2 parts crosslinking agent. The activated waste asphalt mixture is obtained by treating waste asphalt with microwave irradiation and plasma etching. The boron-modified organic vermiculite intercalation anchoring agent is obtained by organic intercalation of vermiculite powder and then modification with boric acid powder.

2. The recycled asphalt mixture mixed with natural asphalt according to claim 1, characterized in that, The activated waste asphalt mixture was prepared using the following method: A1. The waste asphalt is crushed and screened to an average particle size of 10-20mm, and then placed in a closed microwave reaction chamber. It is irradiated with microwave at a frequency of 2.2-2.5GHz and a power of 350-450W for 8-12 minutes. Saturated water vapor is introduced simultaneously with the irradiation. After the irradiation is completed, the desorbed and activated waste asphalt mixture is obtained. A2. Transfer the desorbed and activated waste asphalt mixture into a plasma treatment device, introduce high-purity argon gas, and perform plasma etching treatment for 6-10 minutes at a discharge power of 120-160W and a treatment temperature of 45-60℃. After the etching treatment is completed, spray 0.5%-1.5% of the mass of the silane coupling agent solution, stir for 5-10 minutes, and then vacuum dry at 60-80℃ to obtain the activated waste asphalt mixture.

3. The recycled asphalt mixture mixed with natural asphalt according to claim 1, characterized in that: The regenerant is one of 1-butyl-3-methylimidazolium thiocyanate ionic liquid or cycloalkane aromatic regenerant.

4. The recycled asphalt mixture mixed with natural asphalt according to claim 1, characterized in that, The boron-modified organic vermiculite intercalation anchoring agent was prepared using the following method: B1. Disperse vermiculite powder in an ethanol solution, add hexadecyltrimethylammonium bromide, stir at a constant temperature of 70-80℃ for 3-4 hours, filter and wash until no bromide ions are detected, and dry at 90-100℃ to obtain organic intercalated vermiculite; B2. Mix organic intercalated vermiculite with boric acid powder, place in a muffle furnace, heat to 180-220℃ at 5℃ / min, calcine in a constant temperature solid phase for 1-2 hours, and then cool naturally. Grind the calcined product into powder using an air jet mill and pass it through a 200-mesh sieve to obtain boron-modified organic vermiculite intercalation anchoring agent.

5. A recycled asphalt mixture mixed with natural asphalt according to claim 4, characterized in that: In step B1, the mass concentration of the ethanol solution is 60%-70%; the mass ratio of the vermiculite powder to the ethanol solution is 1:(8-10).

6. A recycled asphalt mixture mixed with natural asphalt according to claim 4, characterized in that: In step B1, the mass ratio of vermiculite powder to hexadecyltrimethylammonium bromide is (4-5):

1.

7. A recycled asphalt mixture mixed with natural asphalt according to claim 4, characterized in that: In step B2, the mass ratio of organic intercalated vermiculite to boric acid powder is (8-10):

1.

8. A recycled asphalt mixture mixed with natural asphalt according to claim 1, characterized in that: The basalt fibers are 4-8 mm in length.

9. A recycled asphalt mixture mixed with natural asphalt according to claim 1, characterized in that: The crosslinking agent comprises sulfur and zinc oxide in a mass ratio of (2-3):

1.

10. A method for preparing a recycled asphalt mixture doped with natural asphalt according to any one of claims 1-9, characterized in that, Includes the following steps: Activated waste asphalt mixture, basalt crushed stone, and limestone mineral powder are mixed and stirred at 110-120℃ for 3-5 minutes. Then, a recycling agent and base asphalt are added and stirred at 120-150℃ for 18-22 minutes. Next, rubber powder and crosslinking agent are added and stirred at 140-145℃ for 8-10 minutes. Finally, boron-modified organic vermiculite intercalation anchoring agent, natural rock asphalt, and basalt fiber are added and stirred at 138-142℃ for 10-14 minutes. After cooling, a recycled asphalt mixture mixed with natural asphalt is obtained.

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