Epoxy recycled asphalt mixture and method for preparing the same

Abstract

The application discloses an epoxy reclaimed asphalt mixture and a preparation method thereof, and belongs to the technical field of waste asphalt recycling, wherein through optimization of a reclaimed agent formula, aggregate pretreatment technology and construction of a matched epoxy asphalt composite system, RAP 100% efficient recycling is realized, the Marshall stability of the prepared epoxy reclaimed asphalt mixture is greater than or equal to 20kN, the dynamic stability is greater than or equal to 10000 times / mm, and the freeze-thaw splitting strength ratio is greater than or equal to 90%, so that all performance indexes meet the application requirements of highway engineering, a green, economical and high-performance reclaimed material solution is provided for road engineering, and engineering cost is reduced, resource waste and environmental pollution are reduced.

Description

Technical Field

[0001] This invention belongs to the field of waste asphalt recycling technology, specifically relating to an epoxy recycled asphalt mixture and its preparation method. Background Technology

[0002] Asphalt pavements are widely used in highways and municipal road infrastructure due to their advantages of high smoothness, good driving comfort, and convenient construction. However, as they age, pavements are prone to cracking, rutting, and loosening, generating large amounts of waste asphalt mixture (RAP) during maintenance. Traditional landfill and disposal methods not only waste high-quality asphalt and aggregate resources but also occupy land and cause environmental pollution.

[0003] Currently, the recycling rate of RAP is mostly between 30% and 50%, making it difficult to achieve 100% recycling. Existing technologies for RAP recycling mainly include conventional thermal recycling technology, recycling technology with the addition of common recycling agents, and some epoxy asphalt recycling technologies. Conventional hot recycling technology simply heats and sieves RAP, then blends it with some new aggregates and new asphalt, achieving a recycling rate of only 30%–50%. This fails to fully utilize RAP resources and does not address the issues of old asphalt aging and aggregate gradation imbalance, resulting in limited performance of recycled materials. Ordinary recycling agent technology repairs old asphalt performance by adding single-component or simply compounded recycling agents, but the recycler has poor compatibility with old asphalt and subsequent bonding systems, and it does not optimize for aggregate gradation issues in 100% RAP recycling, easily leading to segregation and insufficient water stability. Existing epoxy asphalt recycling technology, while attempting to use RAP for epoxy asphalt recycling in some cases, has significant drawbacks: it does not specifically address the issues of old asphalt aging and aggregate gradation imbalance, resulting in unstable recycled material performance; epoxy asphalt systems often use formulations from steel bridge deck paving, leading to high costs and poor compatibility with the requirements of 100% RAP recycling; and the recycling agent has poor integration with the epoxy system, resulting in short construction dwell time and difficulty in meeting engineering construction requirements.

[0004] Existing research shows that epoxy asphalt, with its high strength, high modulus, excellent fatigue resistance and water damage resistance, can enhance the performance of hot recycled asphalt mixtures. Some technologies have achieved 80% to 100% RAP content, but there are still problems such as insufficient compatibility of recycling agents, poor integration between epoxy system and old asphalt, and difficulty in controlling construction retention time. Summary of the Invention

[0005] To address the technical problems of insufficient compatibility of existing recycling agents, poor integration of epoxy systems with old asphalt, and difficulty in controlling construction retention time, this invention provides an epoxy recycled asphalt mixture and its preparation method. By optimizing the recycling agent formulation, improving the aggregate pretreatment process, and constructing a suitable epoxy asphalt composite system, this invention achieves 100% efficient recycling of RAP (Rich Asphalt Particulate Epoxy) and produces epoxy asphalt materials with high strength, good durability, and strong stability. This provides a green, economical, and high-performance recycled material solution for road engineering, while reducing engineering costs, resource waste, and environmental pollution.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The first objective of this invention is to provide an epoxy recycled asphalt mixture, wherein the epoxy recycled asphalt mixture is made by mixing waste asphalt mixture as aggregate with a recycling agent and an epoxy asphalt composite system.

[0008] The regenerator is prepared by mixing waste rubber powder and tung oil-modified phenolic resin at 125℃~135℃ to obtain a premix; adding polyphosphoric acid, nano-calcium carbonate, antioxidant, and ultraviolet absorber to the premix and mixing evenly; then adding 0.8%~2.5% of silane coupling agent by mass of the total regenerator and continuing to mix.

[0009] The waste asphalt mixture has a moisture content of ≤0.5%, a particle size of ≤26.5mm, a penetration of ≥15 (with 0.1mm as 1 unit), a softening point of ≥40℃, and a ductility of ≥10cm at 15℃.

[0010] The epoxy asphalt composite system is composed of 20-40 parts of bisphenol A type E-51 epoxy resin, 34-66 parts of base asphalt, 10-20 parts of curing agent and 4-6 parts of diluent.

[0011] In a preferred embodiment, the mass ratio of the waste rubber powder to the tung oil-modified phenolic resin is 1:2.5-4; based on the mass of the premix, the mass percentage of the polyphosphoric acid is 1%-3%; the mass percentage of the nano-calcium carbonate is 2%-5%; the mass percentage of the antioxidant is 0.2%-0.8%; and the mass percentage of the ultraviolet absorber is 0.3%-1.0%.

[0012] In a preferred embodiment, the waste rubber powder has a particle size of 40-80 mesh, preferably waste tire rubber powder; the antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010); the ultraviolet absorber is 2-hydroxy-4-octyloxybenzophenone (UV-531); and the silane coupling agent is γ-aminopropyltriethoxysilane (KH-550).

[0013] In a preferred embodiment, the particle size includes 0.1mm to 2.36mm, 2.36mm to 4.75mm, 4.75mm to 9.5mm, 9.5mm to 13.2mm, 13.2mm to 19mm, and 19mm to 26.5mm.

[0014] In a preferred embodiment, the penetration of the base bitumen is 60-80 (with 0.1 mm as one unit).

[0015] In a preferred embodiment, the curing agent is polyamide curing agent 650 and the diluent is butyl glycidyl ether.

[0016] As a preferred embodiment, the epoxy recycled asphalt mixture has a Marshall stability ≥20kN, a dynamic stability ≥10000 cycles / mm, and a freeze-thaw splitting strength ratio ≥90%.

[0017] The second objective of this invention is to provide a method for preparing epoxy recycled asphalt mixture, characterized by comprising the following steps: Waste rubber powder and tung oil-modified phenolic resin are mixed to obtain a premix. Polyphosphoric acid, nano-calcium carbonate, antioxidant, and ultraviolet absorber are added to the premix and mixed evenly. Then, a silane coupling agent is added and mixed further to obtain the regenerator.

[0018] An epoxy asphalt composite system is obtained by mixing epoxy resin, curing agent, diluent, and base asphalt.

[0019] Waste asphalt mixture is heated at 135℃~145℃ to obtain softened aggregate. A recycling agent is added to allow the recycling agent to penetrate into the softened aggregate. Then, an epoxy asphalt composite system is added and mixed evenly to obtain epoxy recycled asphalt mixture.

[0020] In a preferred embodiment, the recycling agent accounts for 1% to 1.5% of the mass of the waste asphalt mixture.

[0021] In a preferred embodiment, the epoxy asphalt composite system accounts for 3% to 6% of the mass of the waste asphalt mixture.

[0022] In one preferred embodiment, the epoxy recycled asphalt mixture is placed in a mold, compacted at 135℃~145℃, cured for 2 hours, and then cured at 60℃ for 48h~72h.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses waste asphalt mixture as aggregate, and mixes the aggregate with a recycling agent and an epoxy asphalt composite system to obtain epoxy recycled asphalt mixture, achieving 100% efficient recycling of RAP.

[0024] 1. Material performance optimization effect: The targeted design of the adaptive recycling agent, through the synergistic effect of multiple raw materials, effectively repairs the adhesion and flexibility of aged asphalt. At the same time, the addition of silane coupling agent improves the compatibility with the epoxy system. Combined with RAP fine pretreatment and gradation optimization, it solves the problems of aggregate gradation imbalance and poor interfacial adhesion, effectively avoiding the defects of mixture segregation and poor water stability. The compounded antioxidants and ultraviolet absorbers enhance the anti-aging ability of recycled materials and extend their service life.

[0025] 2. Core performance meets standards: The constructed epoxy asphalt composite system has good synergy with the recycling agent and RAP aggregate, giving the 100% epoxy RAP asphalt mixture high strength, high modulus and excellent durability. Tests show that the prepared epoxy recycled asphalt mixture has a Marshall stability ≥ 20kN, dynamic stability ≥ 10000 cycles / mm, and freeze-thaw splitting strength ratio ≥ 90%. All performance indicators meet the requirements for highway engineering applications.

[0026] 3. Construction and promotion effects: The preparation process is simple and controllable, and the required equipment is conventional equipment for road material production. By optimizing the raw material ratio and process parameters, the viscosity growth rate of the epoxy asphalt composite system is controlled to ensure that the construction dwell time is ≥4h.

[0027] 4. Resource utilization and environmental protection effects: Achieve 100% recycling of RAP without adding new aggregates, maximize the resource value of aggregates and old asphalt in RAP, significantly reduce raw material consumption and engineering costs, reduce environmental pollution caused by RAP landfill, and conform to the concept of green and sustainable development. Attached Figure Description

[0028] Figure 1 Marshall stability test of the epoxy asphalt recycled mixtures prepared in Example 1 and Comparative Example 1 of this invention.

[0029] Figure 2 The dynamic stability test was conducted on the epoxy asphalt recycled mixtures prepared in Example 1 and Comparative Example 1 of this invention.

[0030] Figure 3 This test examines the freeze-thaw splitting strength ratio of the epoxy asphalt recycled mixtures prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0032] Existing research shows that epoxy asphalt, with its high strength, high modulus, excellent fatigue resistance and water damage resistance, can enhance the performance of hot recycled asphalt mixtures. Some technologies have achieved 80% to 100% RAP content, but there are still problems such as insufficient compatibility of recycling agents, poor integration between epoxy system and old asphalt, and difficulty in controlling construction retention time.

[0033] The technical solution of the present invention will be analyzed in detail below.

[0034] This invention provides an epoxy recycled asphalt mixture, which is made by mixing waste asphalt mixture as aggregate with a recycling agent and an epoxy asphalt composite system.

[0035] The regenerator is prepared by mixing waste rubber powder and tung oil-modified phenolic resin (purchased from Yoshida Chemical, model BF03) at 125℃~135℃ to obtain a premix; polyphosphoric acid (industrial polyphosphoric acid 300g / mol~400g / mol), nano calcium carbonate (20nm~80nm), antioxidant, and ultraviolet absorber are added to the premix and mixed evenly; then 0.8%~2.5% of silane coupling agent by mass of the total regenerator is added and mixed further to obtain the final product.

[0036] The waste asphalt mixture has a moisture content of ≤0.5%, a particle size of ≤26.5mm, a penetration of ≥15 (with 0.1mm as 1 unit), a softening point of ≥40℃, and a ductility of ≥10cm at 15℃.

[0037] The epoxy asphalt composite system is composed of 20-40 parts of bisphenol A type E-51 epoxy resin, 34-66 parts of base asphalt, 10-20 parts of curing agent and 4-6 parts of diluent.

[0038] In the above technical solution, this invention uses waste asphalt mixture as aggregate, which is mixed with a recycling agent and an epoxy asphalt composite system to obtain epoxy recycled asphalt mixture. By optimizing the recycling agent formula, aggregate pretreatment process, and constructing a suitable epoxy asphalt composite system, 100% efficient regeneration of RAP is achieved, producing epoxy asphalt materials with high strength, good durability, and strong stability. Its multi-functional compound design breaks through the limitations of single-component recycling agents, synergistically combining tung oil-modified phenolic resin (enhancing adhesion), polyphosphoric acid (adjusting performance), and nano-calcium carbonate (strengthening strength) to meet multiple needs of repair, compatibility, and strengthening. By optimizing the recycling agent through silane coupling agent composition, it achieves strong interfacial adhesion with the epoxy system, old asphalt, and RAP aggregate, avoiding segregation of the mixture. It can efficiently repair the adhesion and flexibility of aged old asphalt, solving the core problem of old asphalt performance degradation during 100% RAP regeneration. Using carefully selected waste tire rubber powder as the core component, it combines the dual value of resource recycling and performance enhancement, aligning with the green concept. It is also compounded with antioxidants and UV absorbers to improve the anti-aging and UV resistance of recycled materials, extend their service life, and precisely match 100% RAP recycling scenarios. It does not rely on new aggregates and has good synergistic effects with subsequent epoxy asphalt composite systems.

[0039] The preparation process of this invention is simple and controllable, and the required equipment is conventional equipment for road material production. By optimizing the raw material ratio and process parameters, the viscosity growth rate of the epoxy asphalt composite system is controlled to ensure that the construction dwell time is ≥4h. It is easy to promote industrialization and is applicable to various scenarios such as highway maintenance and municipal road construction.

[0040] The technical solution of the present invention will be further illustrated below through the following embodiments and comparative examples.

[0041] Example 1 A method for preparing epoxy recycled asphalt mixture includes the following steps: S1, RAP fine preprocessing: RAP Screening and Impurity Removal: The recovered RAP is screened in multiple stages. First, it is screened through a 26.5mm sieve to remove impurities such as oversized stones and metal fragments. Then, it is screened through 19mm, 13.2mm, 9.5mm, 4.75mm, and 2.36mm sieves in sequence to obtain six grades of aggregate: 0.1mm~2.36mm, 2.36mm~4.75mm, 4.75mm~9.5mm, 9.5mm~13.2mm, 13.2mm~19mm, and 19mm~26.5mm.

[0042] RAP drying and moisture content control: According to the required gradation requirements, weigh the graded RAP aggregates and put them into the drying equipment. Dry them at 105℃±5℃ for 2 hours until the moisture content is ≤0.5%. Cool them to room temperature for later use to avoid moisture affecting the subsequent mixing quality of the aggregates.

[0043] RAP gradation optimization and adjustment: The gradation of each grade of RAP aggregate after drying is tested. Referring to the target gradation requirements of AC-13, AC-16 or AC-20 in the "Technical Specification for Construction of Highway Asphalt Pavement", the aggregate gradation is optimized by mechanically crushing the coarse aggregate particle size and supplementing with RAP crushed fine aggregate of the same particle size. This ensures that the gradation curve is smooth and within the target gradation range, without the need to add new aggregate.

[0044] Rapid evaluation of old asphalt performance: The old asphalt in a portion of RAP is extracted using the extraction-rotary evaporation method, and its penetration, softening point, and ductility (5℃) are tested to assess the degree of aging and provide a basis for subsequent adjustment of the amount of recycling agent.

[0045] S2, Regenerant Preparation: Premix raw material ratio (by weight): Under the conditions of 135℃ and 900r / min, select 10 parts of waste rubber powder (particle size 40-80 mesh, preferably waste tire rubber powder) and 40 parts of tung oil modified phenolic resin, mix and stir for 35 minutes to fully blend and obtain the premix.

[0046] Preparation of regenerator: At 125℃ and 700r / min, based on the mass of the premix, 3% polyphosphoric acid (PPA), 5% nano-calcium carbonate, 0.8% antioxidant (antioxidant 1010), and 1.0% ultraviolet absorber (UV-531) were added sequentially to the premix and mixed evenly. Then, 2.5% of silane coupling agent (KH-550) was added according to the total mass of the regenerator, and stirring was continued for 25min to obtain the regenerator. After cooling to room temperature, it was sealed and stored. This regenerator can effectively repair the performance of aged asphalt and improve its compatibility with epoxy systems.

[0047] Preparation of S3, RAP100% recycled epoxy asphalt mixture: Epoxy asphalt composite system (by weight): 20 parts epoxy resin (bisphenol A type E-51), 10 parts curing agent (polyamide curing agent 650), 4 parts diluent (butyl glycidyl ether), and 66 parts new base asphalt (penetration 60-80).

[0048] RAP aggregate preheating and addition of recycling agent and epoxy asphalt composite system: Add the S1-treated RAP aggregate to the asphalt mixture mixing pot, heat to 135℃, and keep warm for 60 minutes to fully preheat the aggregate and initially soften the old asphalt; add the recycling agent prepared by S2 at 1% of the weight of RAP aggregate, and stir for 60 seconds at 135℃ and 60 r / min to allow the recycling agent to fully penetrate into the old asphalt and repair its aging properties; add the epoxy asphalt composite system at 3% of the weight of RAP aggregate, and continue stirring at 135℃ and 60 r / min for 60 seconds.

[0049] Compaction and curing: The mixed material is fed into the corresponding mold and compacted at 135℃. Then it is cured at 135℃ for 2 hours and then cured at 60℃ for 48 hours to obtain epoxy recycled asphalt mixture.

[0050] Example 2 A method for preparing epoxy recycled asphalt mixture includes the following steps: S1, RAP fine preprocessing: RAP Screening and Impurity Removal: The recovered RAP is screened in multiple stages. First, it is screened through a 26.5mm sieve to remove impurities such as oversized stones and metal fragments. Then, it is screened through 19mm, 13.2mm, 9.5mm, 4.75mm, and 2.36mm sieves in sequence to obtain six grades of aggregate: 0.1mm~2.36mm, 2.36mm~4.75mm, 4.75mm~9.5mm, 9.5mm~13.2mm, 13.2mm~19mm, and 19mm~26.5mm.

[0051] RAP drying and moisture content control: According to the required gradation requirements, weigh the graded RAP aggregates and put them into the drying equipment. Dry them at 105℃±5℃ for 1.5h until the moisture content is ≤0.5%. Cool them to room temperature for later use to avoid moisture affecting the subsequent mixing quality of the aggregates.

[0052] RAP gradation optimization and adjustment: The gradation of each grade of RAP aggregate after drying is tested. Referring to the target gradation requirements of AC-13, AC-16 or AC-20 in the "Technical Specification for Construction of Highway Asphalt Pavement", the aggregate gradation is optimized by mechanically crushing the coarse aggregate particle size and supplementing with RAP crushed fine aggregate of the same particle size. This ensures that the gradation curve is smooth and within the target gradation range, without the need to add new aggregate.

[0053] Rapid evaluation of old asphalt performance: The old asphalt in a portion of RAP is extracted using the extraction-rotary evaporation method, and its penetration, softening point, and ductility (5℃) are tested to assess the degree of aging and provide a basis for subsequent adjustment of the amount of recycling agent.

[0054] S2, Regenerant Preparation: Recycling agent raw material ratio (by weight): Under the conditions of 130℃ and 925r / min, select 10 parts of waste rubber powder (particle size 40-80 mesh, preferably waste tire rubber powder) and 32.5 parts of tung oil modified phenolic resin, mix and stir for 38 minutes to fully blend and obtain premix.

[0055] Preparation of the rejuvenator: At 130℃ and 725r / min, based on the mass of the premix, 2% polyphosphoric acid (PPA), 3.5% nano-calcium carbonate, 0.5% antioxidant (antioxidant 1010), and 0.65% ultraviolet absorber (UV-531) were added sequentially and mixed evenly. Then, 1.65% of the total mass of the rejuvenator, silane coupling agent (KH-550), was added, and stirring was continued for 28 min to obtain the rejuvenator. After cooling to room temperature, it was sealed and stored. This rejuvenator can effectively repair the properties of aged asphalt and improve its compatibility with epoxy systems.

[0056] Preparation of S3, RAP100% recycled epoxy asphalt mixture: Epoxy asphalt composite system (by weight): 30 parts epoxy resin (bisphenol A type E-51), 15 parts curing agent (polyamide curing agent 650), 5 parts diluent (butyl glycidyl ether), and 50 parts new base asphalt (penetration 60-80).

[0057] RAP aggregate preheating and addition of recycling agent and epoxy asphalt composite system: Add the S1-treated RAP aggregate to the asphalt mixture mixing pot, heat to 140℃, and keep warm for 100 minutes to fully preheat the aggregate and initially soften the old asphalt; add the recycling agent prepared by S2 at 1.25% of the weight of RAP aggregate, and stir for 60 seconds at 140℃ and 80 r / min to allow the recycling agent to fully penetrate into the old asphalt and repair its aging properties; add the epoxy asphalt composite system at 5% of the weight of RAP aggregate, maintain the temperature at 140℃ and the speed at 80 r / min, and continue stirring for 60 seconds.

[0058] Compaction and curing: The mixed material is fed into the corresponding mold and compacted at 140℃. Then it is cured at 140℃ for 2 hours and then cured at 60℃ for 60 hours to obtain epoxy recycled asphalt mixture.

[0059] Example 3 A method for preparing epoxy recycled asphalt mixture includes the following steps: S1, RAP fine preprocessing: RAP Screening and Impurity Removal: The recovered RAP is screened in multiple stages. First, it is screened through a 26.5mm sieve to remove impurities such as oversized stones and metal fragments. Then, it is screened through 19mm, 13.2mm, 9.5mm, 4.75mm, and 2.36mm sieves in sequence to obtain six grades of aggregate: 0.1mm~2.36mm, 2.36mm~4.75mm, 4.75mm~9.5mm, 9.5mm~13.2mm, 13.2mm~19mm, and 19mm~26.5mm.

[0060] RAP drying and moisture content control: According to the required gradation requirements, weigh the graded RAP aggregates and put them into the drying equipment. Dry them at 105℃±5℃ for 3 hours until the moisture content is ≤0.5%. Cool them to room temperature for later use to avoid moisture affecting the subsequent mixing quality of the aggregates.

[0061] RAP gradation optimization and adjustment: The gradation of each grade of RAP aggregate after drying is tested. Referring to the target gradation requirements of AC-13, AC-16 or AC-20 in the "Technical Specification for Construction of Highway Asphalt Pavement", the aggregate gradation is optimized by mechanically crushing the coarse aggregate particle size and supplementing with RAP crushed fine aggregate of the same particle size. This ensures that the gradation curve is smooth and within the target gradation range, without the need to add new aggregate.

[0062] Rapid evaluation of old asphalt performance: The old asphalt in a portion of RAP is extracted using the extraction-rotary evaporation method, and its penetration, softening point, and ductility (5℃) are tested to assess the degree of aging and provide a basis for subsequent adjustment of the amount of recycling agent.

[0063] S2, Regenerant Preparation: Recycling agent raw material ratio (by weight): Under the conditions of 125℃ and 950r / min, select 10 parts of waste rubber powder (particle size 40-80 mesh, preferably waste tire rubber powder) and 25 parts of tung oil modified phenolic resin, mix and stir for 40 minutes to fully blend and obtain premix.

[0064] Preparation of regenerator: At 135℃ and 750r / min, based on the mass of the premix, 1% polyphosphoric acid, 2% nano-calcium carbonate, 0.2% antioxidant (antioxidant 1010), and 0.3% ultraviolet absorber (UV-531) were added sequentially to the premix and mixed evenly. Then, 0.8% of silane coupling agent (KH-550) was added according to the total mass of the regenerator, and stirring was continued for 30 min to obtain the regenerator. After cooling to room temperature, it was sealed and stored. This regenerator can effectively repair the performance of aged asphalt and improve its compatibility with epoxy systems.

[0065] Preparation of S3, RAP100% recycled epoxy asphalt mixture: Epoxy asphalt composite system (by weight): 40 parts epoxy resin (bisphenol A type E-51), 20 parts curing agent (polyamide curing agent 650), 6 parts diluent (butyl glycidyl ether), and 34 parts new base asphalt (penetration 60-80).

[0066] RAP aggregate preheating and addition of recycling agent and epoxy asphalt composite system: Add the S1-treated RAP aggregate to the asphalt mixture mixing pot, heat to 145℃, and keep warm for 120 minutes to fully preheat the aggregate and initially soften the old asphalt; add the recycling agent prepared by S2 at 1.5% of the weight of RAP aggregate, and stir for 60 seconds at 145℃ and 100 r / min to allow the recycling agent to fully penetrate into the old asphalt and repair its aging properties; add the epoxy asphalt composite system at 6% of the weight of RAP aggregate, and continue stirring at 145℃ and 100 r / min for 60 seconds.

[0067] Compaction and curing: The mixed material is fed into the corresponding mold and compacted at 145℃. Then it is cured at 145℃ for 2 hours and then cured at 60℃ for 72 hours to obtain epoxy recycled asphalt mixture.

[0068] To further illustrate the effects of the present invention, comparative examples are also provided, as follows: Comparative Example 1 A method for preparing epoxy recycled asphalt mixture includes the following steps: S1, RAP standard preprocessing: RAP screening and impurity removal: The recovered RAP is subjected to single screening, using a 19mm screen to remove obviously large impurities (such as stones and metal fragments). No multi-stage fine grading is performed, resulting in only two grades of material: coarse material on the screen and undersize mixture. The undersize mixture contains aggregates of all particle sizes in the range of 0.1mm to 19mm.

[0069] RAP drying treatment: The sieved RAP material is placed into the drying equipment and dried at 110℃ for 2 hours, with the moisture content controlled at 1.0% to 1.5%. After drying, it is naturally cooled to room temperature for subsequent mixing. When the gradation does not meet the target requirements, it is adjusted by adding new aggregate (such as new basalt aggregate).

[0070] The RAP did not further differentiate between particle size ranges; the RAP drying process did not consider the potential impact of moisture on subsequent mixing quality; the aging performance of old asphalt in the RAP was not systematically evaluated, and the amount of recycling agent was determined solely based on experience, without clear indicator testing basis.

[0071] S2, conventional regenerant preparation: The raw material ratio of the regenerator (by weight) is as follows: 15 parts waste engine oil, 5 parts diesel oil, 3 parts rosin resin, and 1 part antioxidant (antioxidant 1076). The raw materials are of a single type and no modified components or compatibility regulators are added.

[0072] Preparation of the recycling agent: All raw materials were directly added to a conventional mixer and stirred for 25 minutes at 80°C and 600 r / min. No step-by-step premixing was required. After stirring, the mixture was cooled to room temperature. The uniformity of mixing was not strictly controlled. This recycling agent can only soften old asphalt in a simple way and cannot effectively repair the aging properties of old asphalt. It also has poor compatibility with epoxy systems.

[0073] S3, Preparation of epoxy recycled asphalt mixture: Epoxy asphalt composite system (by weight): 50 parts epoxy resin (bisphenol A type E-44), 25 parts curing agent (polyamide curing agent 651), 60 parts new base asphalt (penetration 60-80), no diluent added, the system has high viscosity and is difficult to mix.

[0074] RAP aggregate was added to a mixing pot with a recycling agent and epoxy asphalt composite system. The RAP aggregate treated with S1 was added to the mixing pot and heated to 120°C and kept at that temperature for 40 minutes to achieve only the initial preheating of the aggregate. 2% of the total weight of the RAP aggregate was added to the conventional recycling agent prepared with S2 and stirred for 40 seconds at 120°C and 50 r / min. Subsequently, 4% of the total weight of the RAP aggregate was added to the epoxy asphalt composite system and stirred for 40 seconds at 120°C and 50 r / min.

[0075] Compaction and curing: The mixed material is directly fed into the mold and compacted at 120℃. After being left at room temperature for 48 hours, epoxy recycled asphalt mixture is obtained.

[0076] Performance testing Epoxy recycled asphalt mixtures prepared in Example 1 and Comparative Example 1 were tested according to the relevant standards of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), focusing on three core performance indicators: Marshall stability, dynamic stability, and freeze-thaw splitting strength ratio. The test results are shown in the table below. Figure 1 , Figure 2 , Figure 3 As shown.

[0077] Table 1. Test of core performance indicators of epoxy recycled asphalt mixture The test results above show that the epoxy recycled asphalt mixture prepared by this technical solution has significantly better performance in all three core indicators than the mixture prepared by existing technologies. The specific analysis is as follows: 1. Marshall stability: Using a Marshall stability tester, the mixed specimens cured to the specified age were placed in a 60℃ constant temperature water bath for 30-40 minutes. Then, the specimens were placed in the indenter of the tester and loaded at a uniform loading rate of 5 mm / min until the specimens failed. The maximum loading force was recorded as the Marshall stability (unit: kN). Three specimens were tested in each group, and the average value was taken as the final result.

[0078] The results are as follows Figure 1 As shown, the test value of Example 1 is 22.5kN, which is 42.4% higher than that of the comparative example (15.8kN). This indicates that the technical solution effectively improves the overall load-bearing capacity and anti-damage performance of the mixture through refined RAP pretreatment, adaptive regenerator repair and optimized mixing and curing process, and solves the problem of insufficient strength of the mixture in the prior art.

[0079] 2. Dynamic stability: An asphalt mixture rutting tester was used, with the test temperature set at 60℃ and the loading pressure at 0.7MPa. A wheel-type loading method was adopted, with a loading frequency of 42 times / min. The number of loading times when the cumulative deformation of the test specimen reached 25mm was taken as the dynamic stability (unit: times / mm). Three specimens were tested in each group, and the average value was taken as the final result.

[0080] The results are as follows Figure 2 As shown, the test value of Example 1 was 11200 times / mm, which is 64.7% higher than that of the comparative example (6800 times / mm). This indicates that the mixture prepared in Example 1 has excellent rutting resistance and can effectively resist permanent deformation under high temperature environment. This is due to the good compatibility between the adaptable recycling agent and the epoxy asphalt composite system, as well as the precise optimization of RAP gradation, which improves the compactness of the internal structure of the mixture.

[0081] 3. Freeze-thaw splitting strength ratio: The procedure was performed according to method T 0729-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The specific steps are as follows: First, standard cylindrical mixture specimens were prepared, with no less than 6 specimens per group, divided into two groups, A and B (3 specimens per group). Group A, as the standard specimens, was cured in a constant temperature environment of 25℃±0.5℃ to the specified age, and then directly placed on a splitting tensile strength tester. The splitting tensile strength was tested at a loading rate of 5mm / min, and the splitting tensile strength value of each specimen was recorded. The average value was taken as the average splitting tensile strength (R0) of Group A. Group B, as freeze-thaw specimens, was first placed in a sealed bag and an appropriate amount of distilled water was added. (Water level 2mm above the top surface of the specimen) The specimens were frozen in a -18℃±2℃ freezer for 16h±1h, then immediately placed in a 60℃±0.5℃ constant temperature water bath for 24h±1h to complete one freeze-thaw cycle. This freeze-thaw cycle was repeated for a total of three cycles. The specimens from group B were then removed and kept at a constant temperature of 25℃±0.5℃ for 2h±0.5h. The splitting strength was then tested using the same method as group A. The splitting strength value of each specimen was recorded, and the average value was taken as the average splitting strength (R1) of group B. The freeze-thaw splitting strength ratio (TSR) was calculated using the formula TSR=(R1 / R0)×100%, with the result rounded to one decimal place, and this was taken as the final freeze-thaw splitting strength ratio of the mixture.

[0082] The results are as follows Figure 3 As shown, the test value of Example 1 was 93.2%, which is 18.7% higher than that of the comparative example (78.5%). This demonstrates that the mixture prepared in Example 1 of this technical solution has excellent water stability and freeze-thaw resistance. The reason is that the moisture content is strictly controlled to ≤ 0.5% during the RAP pretreatment process, which avoids the damage of residual moisture to the interfacial bonding of the mixture. At the same time, the adaptable recycling agent enhances the adhesion between the old asphalt and the epoxy system and aggregates, and reduces the interfacial peeling phenomenon during the freeze-thaw cycle.

[0083] In summary, this technical solution, through refined RAP pretreatment, preparation of adaptable recycling agents, and optimized mixing and curing processes, not only achieves 100% recycling of RAP, but also significantly improves the mechanical properties, rutting resistance, and water stability of epoxy recycled asphalt mixtures. Compared with existing technologies, it has obvious technical advantages and application value.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An epoxy recycled asphalt mixture, characterized in that, The epoxy recycled asphalt mixture is made by mixing waste asphalt mixture as aggregate with recycling agent and epoxy asphalt composite system; The regenerator is prepared by mixing waste rubber powder and tung oil-modified phenolic resin at 125℃~135℃ to obtain a premix. Polyphosphoric acid, nano-calcium carbonate, antioxidant, and ultraviolet absorber are added to the premix and mixed evenly. Then, 0.8%~2.5% of silane coupling agent by mass of the total regenerator is added and mixed further. The waste asphalt mixture meets the following conditions: moisture content ≤ 0.5%, particle size ≤ 26.5 mm, penetration ≥ 15, softening point ≥ 40℃, and ductility at 15℃ ≥ 10 cm. By weight, the epoxy asphalt composite system is composed of 20 to 40 parts of bisphenol A type E-51 epoxy resin, 34 to 66 parts of base asphalt, 10 to 20 parts of curing agent and 4 to 6 parts of diluent.

2. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The mass ratio of waste rubber powder to tung oil-modified phenolic resin is 1:2.5-4; based on the mass of the premix, the mass percentage of polyphosphoric acid is 1%-3%; the mass percentage of nano-calcium carbonate is 2%-5%; the mass percentage of antioxidant is 0.2%-0.8%; and the mass percentage of ultraviolet absorber is 0.3%-1.0%.

3. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the ultraviolet absorber is 2-hydroxy-4-octoxybenzophenone; and the silane coupling agent is γ-aminopropyltriethoxysilane.

4. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The particle size of the waste asphalt mixture includes 0.1mm~2.36mm, 2.36mm~4.75mm, 4.75mm~9.5mm, 9.5mm~13.2mm, 13.2mm~19mm, and 19mm~26.5mm.

5. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The penetration of the base bitumen is 60-80.

6. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The curing agent is polyamide curing agent 650; the diluent is butyl glycidyl ether.

7. The epoxy recycled asphalt mixture according to claim 1, characterized in that, The epoxy recycled asphalt mixture has a Marshall stability ≥20kN, a dynamic stability ≥10000 cycles / mm, and a freeze-thaw splitting strength ratio ≥90%.

8. The method for preparing epoxy recycled asphalt mixture according to claims 1 to 7, characterized in that, Includes the following steps: Waste rubber powder and tung oil-modified phenolic resin are mixed to obtain a premix. Polyphosphoric acid, nano-calcium carbonate, antioxidant, and ultraviolet absorber are added to the premix and mixed evenly. Then, a silane coupling agent is added and mixed again to obtain the regenerator. An epoxy asphalt composite system is obtained by mixing epoxy resin, curing agent, diluent, and base asphalt. Waste asphalt mixture is heated at 135℃~145℃ to obtain softened aggregate. A recycling agent is added to allow the recycling agent to penetrate into the softened aggregate. Then, an epoxy asphalt composite system is added and mixed evenly to obtain epoxy recycled asphalt mixture.

9. The method for preparing epoxy recycled asphalt mixture according to claim 8, characterized in that, The recycling agent accounts for 1% to 1.5% of the mass of the waste asphalt mixture.

10. The method for preparing epoxy recycled asphalt mixture according to claim 8, characterized in that, The epoxy asphalt composite system accounts for 3% to 6% of the mass of the waste asphalt mixture.

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