An epoxy fully recycled pavement structure and its application

Abstract

This invention relates to the field of road engineering technology, and in particular to an epoxy fully recycled pavement structure and its application. The pavement structure, from bottom to top, consists of a lower layer composed of asphalt mixture or cement-stabilized crushed stone, a middle layer composed of epoxy fully recycled mixture, and a top layer composed of epoxy recycled mixture. The epoxy fully recycled mixture includes: 85-95 parts of recycled asphalt pavement material, 5-10 parts of epoxy recycling agent, 3-6 parts of bio-based modified asphalt, 0.3-1.2 parts of graphene-modified montmorillonite, and 0.2-0.6 parts of amino-functionalized carbon nanotubes. In the top layer, the amount of recycled asphalt pavement material is 40-60% of that used in the middle layer. The middle layer is 100% recycled asphalt pavement material. The epoxy component significantly improves the strength of the mixture and mitigates the adverse effects of recycled material aging. Combined with nano-reinforcement and gradient dosage design, the pavement exhibits excellent comprehensive performance and is suitable for the needs of high-grade highway engineering.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to an epoxy fully recycled pavement structure and its application. Background Technology

[0002] In the field of road engineering, asphalt pavement recycling technology is a key approach to achieving resource recycling. However, traditional recycled pavement structures and material systems have significant limitations. Traditional recycled pavements typically employ a single recycled layer structure or simply use recycled mixtures in the lower layer. This structure fails to fully consider the optimization of the performance gradient distribution of recycled materials. Its core problems are: incomplete activation of aged asphalt, relying mainly on the physical dilution of new asphalt, and failing to reconstruct the colloidal structure of aged asphalt; poor integration of new and old materials at the interface, resulting in weak interlayer bonding; and difficulty in synergistically improving the overall performance of the recycled layer, leading to early pavement damage.

[0003] The limitations of existing technologies are specifically reflected in the following aspects: First, the structural design is simplistic, failing to incorporate functional layering design tailored to the performance characteristics of recycled materials, making it difficult to simultaneously meet the multiple requirements of load-bearing capacity in the lower layer, fatigue resistance in the middle layer, and skid resistance and wear resistance in the upper layer. Second, the material activation mechanism is crude; traditional recycling agents cannot precisely target the chemical cross-linking bonds of fractured aged asphalt, resulting in insufficient activation depth. In existing technologies, the content of recycled asphalt in conventional hot-recycled asphalt mixtures is generally limited to less than 60%. Once the content exceeds 60%, insufficient activation of aged asphalt and poor interfacial compatibility between new and old materials lead to a sharp decline in the low-temperature crack resistance, fatigue resistance, and water stability of the recycled mixture, failing to meet the performance requirements of high-grade highway pavement structural layers and greatly limiting the resource utilization efficiency of waste asphalt pavement materials. Finally, the interfacial performance is weak; the aged asphalt film on the surface of RAP aggregates has poor compatibility with new asphalt, and there is a lack of effective interfacial reinforcement methods, making it a weak link for stress concentration and moisture intrusion.

[0004] Therefore, there is an urgent need for an innovative pavement structure that can systematically solve the above problems by combining functional layered structure design with deep activation-interface enhancement material technology, and achieve high-proportion, high-performance regeneration of RAP.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] This invention provides an epoxy fully recycled pavement structure and its application, which can effectively solve the problems in the background art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides an epoxy fully recycled pavement structure, wherein the pavement structure comprises, from bottom to top, a lower layer composed of asphalt mixture or cement-stabilized crushed stone, an intermediate layer composed of epoxy fully recycled mixture, and an upper layer composed of epoxy recycled mixture. By weight, the epoxy fully recycled mixture includes: 85-95 parts of recycled asphalt pavement (RAP), 5-10 parts of epoxy recycling agent, 3-6 parts of bio-based modified asphalt, 0.3-1.2 parts of graphene-modified montmorillonite, and 0.2-0.6 parts of amine-functionalized carbon nanotubes. In the top layer, the amount of recycled old asphalt pavement material is 40-60% of that used in the middle layer, and the remainder is the same as that of epoxy fully recycled mixture.

[0008] This invention employs a three-layer functionalized structure. The bottom layer provides basic support. The middle layer uses an epoxy fully recycled mixture and 100% recycled old asphalt pavement material. The epoxy regenerator interrupts the cross-linking network of aged asphalt and reconstructs the colloidal structure, achieving deep activation. Simultaneously, graphene-modified montmorillonite and amino-functionalized carbon nanotubes enhance the interface between new and old asphalt and asphalt-aggregate, giving this layer high load-bearing capacity and fatigue resistance. In the top layer of epoxy recycled mixture, the proportion of recycled old asphalt pavement material is controlled to be 40-60% of the recycled material used in the middle layer. While continuing the same activation and enhancement mechanism, the proportion of recycled material is reduced to retain sufficient new asphalt and functional components, thereby ensuring the surface function of the surface layer is dense, skid-resistant, and wear-resistant. The pavement structure of this invention realizes the gradient utilization of old materials in the pavement structure. The middle layer fully utilizes the strength of the recycled material, and the top layer balances recycling and surface performance requirements, improving the overall stability and service life of the pavement.

[0009] Furthermore, by weight percentage, the epoxy regenerator comprises: 25-40% bisphenol A type epoxy resin, 30-50% epoxy modified aromatic amine composite curing agent, 15-35% hydroxyl-terminated polyether polyol toughening agent, and 5-15% epoxy propyl ether reactive diluent.

[0010] In this invention's epoxy regenerator, bisphenol A type epoxy resin serves as the film-forming host of the epoxy system. The epoxy functional groups on its molecular chain can undergo ring-opening crosslinking reactions with the amine functional groups of the epoxy-modified aromatic amine composite curing agent, forming a stable three-dimensional network structure. Simultaneously, the epoxy groups can chemically bond with polar groups in aged asphalt and the amine groups of amine-functionalized carbon nanotubes, achieving synergistic activation of aged asphalt and construction of the composite network. The epoxy-modified aromatic amine composite curing agent provides the main curing reaction sites, and its amine functional groups can target and attack carbonyl and other polar groups in aged asphalt, achieving chemical bond breaking of the crosslinked network and completing the deep activation of the aged asphalt. The hydroxyl-terminated polyether polyol toughening agent, through its long, flexible chain segments, interpenetrates within the newly formed epoxy-asphalt network, endowing the system with the necessary deformation capacity and preventing brittle fracture. The epoxy propylene ether reactive diluent adjusts the viscosity and construction wettability of the entire system, ensuring that it can fully penetrate into the aged asphalt film on the surface of the RAP aggregate. The above-mentioned proportion range ensures a balance between bond breaking activation, network toughening, structural strength, and process applicability, enabling the aged asphalt to immediately participate in the formation of a new epoxy-asphalt composite cementing system with both strength and flexibility after chemical bond breaking, thereby overcoming the problems of incomplete activation and weak interfaces caused by simple physical dilution.

[0011] Furthermore, the bio-based modified bitumen is a composite modified product of castor oil-based bio-bitumen and base bitumen, wherein the amount of castor oil-based bio-bitumen accounts for 15-30% of the total mass of the bio-based modified bitumen.

[0012] Castor oil-based bioasphalt is rich in highly polar functional groups such as hydroxyl and ester groups. These groups are thermodynamically compatible with the oxygen-containing polar components in aged asphalt, which can promote the mutual diffusion and fusion between new and old asphalt. When the dosage is in the range of 15-30%, it is sufficient to form an effective polar network in the continuous phase of asphalt, which can enhance its wetting and penetration ability on the aged asphalt film on the RAP surface, while avoiding excessive reduction of the system's high-temperature viscosity and overall mechanical strength due to excessive introduction of bioasphalt.

[0013] Preferably, the preparation method of bio-based modified asphalt is as follows: castor oil-based bio-asphalt and base asphalt heated to a fluid state are added into a mixing tank in proportion, and sheared and stirred at a speed of 300-500 rpm for 20-40 minutes within a temperature range of 160-180℃ until uniformly mixed to form a homogeneous and stable bio-based modified asphalt.

[0014] Furthermore, the interlayer spacing of the graphene-modified montmorillonite is 2.0~3.5 nm, and the loading of graphene in montmorillonite is 1.5~3.0%.

[0015] Graphene-modified montmorillonite has an interlayer spacing of 2.0~3.5nm, which allows its sheet structure to effectively accommodate asphalt components, forming physical interlocks and enhancing the mechanical bonding force between the asphalt matrix and the mineral interface. At the same time, by controlling the loading of graphene in montmorillonite to 1.5~3.0%, graphene can be stably attached to the surface of montmorillonite in the form of nanosheets, constructing a uniformly distributed reinforcing network in the asphalt and improving the bonding strength and deformation resistance of the binder. More specifically, the preparation method of graphene-modified montmorillonite is as follows: purified sodium-based montmorillonite is dispersed in water to form a suspension, an aqueous solution of graphene oxide is added and stirred, and the negative charge on the surface of the montmorillonite sheets is used to electrostatically adsorb the graphene oxide to initially load it; then an intercalating agent is added and reacted at 60~80℃, the intercalating agent enters the interlayer of montmorillonite and expands it to 2.0~3.5nm; finally, the graphene oxide is converted into graphene by reduction treatment, and graphene-modified montmorillonite powder with a loading of 1.5~3.0% is obtained by washing and drying.

[0016] Furthermore, the amino-functionalized carbon nanotubes have a diameter of 20-50 nm, a length of 1-5 μm, and an amino grafting rate of 3.2-5.8%.

[0017] The size of the aforementioned amine-functionalized carbon nanotubes makes them easier to disperse in the asphalt matrix and allows them to form a three-dimensional network structure within the binder through their large aspect ratio, effectively transferring and dispersing stress. The aforementioned amine grafting rate gives the nanotubes sufficient amine density, enabling the amine functional groups to chemically react with the epoxy groups in the epoxy regenerator or the polar components in the asphalt, forming a strong chemical bond between the carbon nanotubes and the asphalt matrix. This effectively imparts the excellent mechanical properties of the carbon nanotubes to the entire binder system, strengthens the interface, and improves the overall stiffness and crack resistance of the mixture.

[0018] Furthermore, the preparation method of the epoxy regenerator includes: S1. Bisphenol A type epoxy resin and hydroxyl-terminated polyether polyol toughening agent are mixed evenly at 80~90℃. The above temperature range promotes the physical compatibility and prepolymerization reaction of epoxy resin and toughening agent, so that the toughening agent is evenly dispersed in epoxy resin matrix, laying the foundation for the subsequent formation of a cured network with both strength and flexibility. S2. Add epoxy-modified aromatic amine composite curing agent to the mixture in step S1 and continue stirring at the same temperature; this step achieves uniform dispersion of the curing agent in the epoxy matrix and avoids uneven system caused by excessively rapid local reaction; After mixing S3, the temperature is lowered to 50-60℃, and epoxy propylene ether reactive diluent is slowly added. After mixing, the epoxy regenerator is obtained after vacuum degassing. The addition of epoxy propylene ether reactive diluent after the temperature is lowered to 50-60℃ reduces the volatilization of the diluent, which lowers the viscosity of the system and improves the wetting and penetration efficiency of the epoxy regenerator on aged asphalt during construction. The vacuum degassing step eliminates air bubbles introduced during mixing, avoids the formation of defects after curing, and ensures the homogeneity and storage stability of the epoxy regenerator components.

[0019] Furthermore, the preparation method of the epoxy fully recycled mixture includes: Q1 The old asphalt pavement material milled on site is screened by vibration to obtain old asphalt pavement recycled material, which is then dried at 140~150℃ for later use; drying can avoid moisture causing poor asphalt coating or generating steam pressure during subsequent hot mixing process; Q2 Weigh out the epoxy regenerator and bio-based modified asphalt, heat them separately to 120~130℃ and keep them warm for later use. This can keep the two liquid materials at a low viscosity and good fluidity. Premix the graphene-modified montmorillonite and amine-functionalized carbon nanotubes for later use. This can initially homogenize the two nanopowders and prevent them from agglomerating due to static electricity or other reasons when they are added separately in the mixing pot. Q3. Pre-stir the heated recycled asphalt pavement for 10-20 seconds; then add epoxy recycling agent, maintain the temperature at 135-145℃, and stir for 30-40 seconds to allow the epoxy recycling agent to flow fully and penetrate into the aged asphalt film on the surface of the RAP aggregate, completing the chemical activation of the aged asphalt; then add bio-based modified asphalt and continue stirring for 20-30 seconds. The activated asphalt interface has better compatibility with the bio-based modified asphalt. This step further integrates the new and old asphalt and forms a continuous and uniform cementitious film to coat the aggregate. Q4 Then add the premixed graphene-modified montmorillonite and amine-functionalized carbon nanotubes, stir and disperse to obtain epoxy fully recycled mixture; add premixed nanomaterials and stir and disperse, the graphene-modified montmorillonite and amine-functionalized carbon nanotubes achieve nanoscale distribution in the formed asphalt binder through mechanical stirring, the montmorillonite sheets and carbon nanotube network play a role in physical reinforcement and stress transfer, and finally obtain a uniformly structured epoxy fully recycled mixture.

[0020] The above preparation method first adds epoxy regenerator separately and keeps it warm while stirring, providing sufficient time and temperature conditions for it to specifically penetrate and chemically activate aged asphalt. This is a key prerequisite for achieving deep regeneration. Then, bio-based modified asphalt is added. At this point, the activated asphalt interface is more likely to fuse with it, forming a continuous cementitious phase with uniform properties. Finally, nano-reinforcing materials are added to the formed uniform asphalt binder. This avoids the nanomaterials being wrapped or isolated by unactivated aged asphalt or unfused components, ensuring that they can be directly and fully dispersed in the effective cementitious phase, maximizing their interface reinforcement and network construction effects.

[0021] Furthermore, the epoxy fully recycled mixture is prepared under closed conditions.

[0022] The sealed environment provides a stable reaction medium for the chemical activation process of aged asphalt by epoxy rejuvenator, reduces oxygen interference, and ensures that the activation reaction proceeds fully.

[0023] Furthermore, the particle size of the recycled asphalt pavement aggregate is 5~25mm. This particle size range ensures that the recycled aggregate has a suitable gradation, enabling it to form a good skeleton interlocking structure in the mixture, thereby providing stable mechanical support and deformation resistance for the epoxy fully recycled mixture. The second aspect of this invention provides the application of the above-mentioned epoxy fully recycled pavement structure in the reconstruction and expansion of high-grade highways and the maintenance and renovation of old pavements.

[0024] The technical solution of this invention can achieve the following technical effects: The pavement structure of this invention comprises a lower layer of conventional asphalt mixture or cement-stabilized crushed stone, whose main function is to provide solid structural support and load distribution foundation for the pavement; a middle layer of epoxy fully recycled mixture prepared with 100% ultra-high RAP content, breaking through the industry bottleneck of 60% content in existing technologies, mainly bearing and dispersing traffic loads, and endowed with outstanding fatigue resistance and load-bearing capacity through epoxy regenerator and nano-reinforcing components in the material system; and an upper layer of epoxy recycled mixture, which optimizes the pavement surface characteristics and ensures sufficient anti-skid, wear-resistant and durability properties to meet the requirements of driving safety and long-term use. In the intermediate layer of this invention, the epoxy regenerator targets the cross-linked network of fractured and aged asphalt and introduces flexible segments to complete the chemical activation and reconstruction of the colloidal structure. On this basis, bio-based modified asphalt promotes the fusion of new and old asphalt and improves workability. Graphene-modified montmorillonite and amine-functionalized carbon nanotubes synergistically enhance the bonding between the asphalt-aggregate interface and the new and old asphalt at the nanoscale, thereby improving the overall strength and durability of the material. Furthermore, during the preparation of the intermediate layer, precise feeding sequence and temperature control ensure that the special epoxy regenerator fully penetrates and activates the RAP, and that the functional components are uniformly dispersed and effectively synergistic, ultimately achieving continuous and stable production of high-performance epoxy fully recycled mixtures. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of an epoxy fully recycled pavement structure. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] 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 in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Example 1:

[0030] This embodiment provides an epoxy fully recycled pavement structure and its preparation method, the specific steps of which are as follows: (1) The raw material preparation process is as follows: Recycled Asphalt Pavement (RAP): Old asphalt pavement materials are milled and recycled on-site. After being screened by vibration, RAP aggregates with a particle size of 5~25mm are selected, placed in a heated drum, and dried at 145℃ until there are no water marks on the surface, and then set aside for use. Epoxy Regenerator: By weight percentage, 32% bisphenol A type epoxy resin, 35% epoxy-modified aromatic amine composite curing agent, 20% hydroxyl-terminated polyether polyol toughening agent, and 13% epoxy propylene ether reactive diluent are used for preparation. First, the bisphenol A type epoxy resin and hydroxyl-terminated polyether polyol toughening agent are stirred and mixed at 85°C and 250 rpm for 18 minutes. Then, the epoxy-modified aromatic amine composite curing agent is added, and the mixture is stirred continuously at the same temperature for 10 minutes. Then, the system temperature is lowered to 55°C, the reactive diluent is slowly added, and the mixture is stirred for another 30 minutes. After vacuum degassing for 12 minutes, 7.5 parts by weight of homogeneous epoxy regenerator are obtained and placed in a storage tank and heated and kept at 125°C for later use. Bio-based modified bitumen: Castor oil-based bio-bitumen (accounting for 22% of the total mass) and base bitumen heated to a fluid state were added to a mixing tank and sheared and stirred at 400 rpm for 30 minutes at 170°C to form 4.5 parts by weight of homogeneous and stable bio-based modified bitumen, which was then heated and kept at 125°C for later use. Nano-reinforcing material: Take 0.75 parts by weight of graphene-modified montmorillonite with a layer spacing of 2.8 nm and a graphene loading of 2.2%, and 0.4 parts by weight of amine-functionalized carbon nanotubes with a tube diameter of 35 nm, a length of 3 μm, and an amine grafting rate of 4.5%. Mix them evenly by dry method beforehand and put them into a dry powder metering silo for later use. (2) The surface layer of the epoxy fully recycled mixture is prepared using a closed mixing pot. The specific steps are as follows: Q1. Add 90 parts by weight of dried and prepared RAP into the mixing pot and pre-stir for 15 seconds to make the aggregate evenly distributed. Q2 Add 7.5 parts by weight of epoxy recycling agent at 125℃ to the mixing pot, keep the mixing system temperature at 140℃, and stir at a constant speed for 35 seconds to allow the recycling agent to fully penetrate and activate the aged asphalt on the RAP surface. Q3 is then added with 4.5 parts by weight of bio-based modified asphalt at 125°C, and stirred for another 25 seconds to promote the fusion of the new and old asphalt and the coating of aggregates. Q4 Finally, add the premixed graphene-modified montmorillonite and amine-functionalized carbon nanotube dry powder mixture, stir and disperse for 75 seconds to ensure that the nanomaterials are evenly distributed in the asphalt binder; continue stirring for 25 seconds to obtain a uniform epoxy fully recycled mixture, and control the discharge temperature at 135~140℃.

[0031] (3) The RAP content of the epoxy recycled mixture is 50% of the weight of the intermediate layer RAP, i.e., 45 parts by weight. The proportions and preparation methods of the remaining components are the same as those of the intermediate layer.

[0032] (4) On the treated and compacted foundation, the epoxy fully recycled pavement structure of the present invention is laid in the following order: Lower layer: Pave and compact conventional AC-20 asphalt mixture, 8cm thick, as a support layer; Intermediate layer: Spread the prepared epoxy fully recycled mixture on the lower layer to a thickness of 6cm and compact it immediately; Top layer: Lay epoxy recycled mixture with a thickness of 4cm, compact and level it. Example 2:

[0033] This embodiment provides an epoxy fully recycled pavement structure and its preparation method, the specific steps of which are as follows: (1) The raw material preparation process is as follows: Recycled Asphalt Pavement (RAP): Old asphalt pavement materials are milled and recycled on-site. After being screened by vibration, RAP aggregates with a particle size of 5~25mm are selected, placed in a heated drum, and dried at 143℃ until there are no water marks on the surface, and then set aside for use. Epoxy Regenerator: By weight percentage, 28% bisphenol A type epoxy resin, 40% epoxy-modified aromatic amine composite curing agent, 18% hydroxyl-terminated polyether polyol toughening agent, and 14% epoxy propylene ether reactive diluent are used for preparation. First, the bisphenol A type epoxy resin and hydroxyl-terminated polyether polyol toughening agent are stirred and mixed at 88℃ and 280 rpm for 17 minutes. Then, the epoxy-modified aromatic amine composite curing agent is added, and the mixture is stirred continuously at the same temperature for 10 minutes. Then, the system temperature is lowered to 58℃, the reactive diluent is slowly added, and the mixture is stirred for another 28 minutes. After vacuum degassing for 13 minutes, 8.0 parts by weight of homogeneous epoxy regenerator are obtained and placed in a storage tank and heated and kept at 128℃ for later use. Bio-based modified bitumen: Castor oil-based bio-bitumen (18% of the total mass) and base bitumen heated to a fluid state are added to a mixing tank and sheared and stirred at 380 rpm for 35 minutes at 165°C to form 5.0 parts by weight of homogeneous and stable bio-based modified bitumen, which is then heated and kept at 128°C for later use. Nano-reinforcing material: Take 0.9 parts by weight of graphene-modified montmorillonite with an interlayer spacing of 3.0 nm and a graphene loading of 2.0%, and 0.5 parts by weight of amine-functionalized carbon nanotubes with a diameter of 40 nm, a length of 4 μm, and an amine grafting rate of 4.0%. Mix them evenly by dry method beforehand and put them into a dry powder metering silo for later use. (2) The surface layer of the epoxy fully recycled mixture is prepared using a closed mixing pot. The specific steps are as follows: Q1. Add 88 parts by weight of dried and prepared RAP into the mixing pot and pre-stir for 18 seconds to make the aggregate evenly distributed. Q2 Add 8.0 parts by weight of epoxy recycling agent at 128℃ to the mixing pot, maintain the mixing system temperature at 142℃, and stir at a constant speed for 38 seconds to allow the recycling agent to fully penetrate and activate the aged asphalt on the RAP surface. Q3 is then added with 5.0 parts by weight of bio-based modified asphalt at 128°C, and stirred for another 28 seconds to promote the fusion of the new and old asphalt and the coating of aggregates. Q4 Finally, add the premixed graphene-modified montmorillonite and amine-functionalized carbon nanotube dry powder mixture, stir and disperse for 78 seconds to ensure that the nanomaterials are evenly distributed in the asphalt binder; continue stirring for 28 seconds to obtain a uniform epoxy fully recycled mixture, and control the discharge temperature at 136~141℃.

[0034] (3) The RAP content of the epoxy recycled mixture is 55% of the weight of the intermediate layer RAP, i.e., 48 parts by weight. The proportions and preparation methods of the remaining components are the same as those of the intermediate layer.

[0035] (4) On the treated and compacted foundation, the epoxy fully recycled pavement structure of the present invention is laid in the following order: Lower layer: Pave and compact conventional AC-25 asphalt mixture, 9cm thick, as a support layer; Intermediate layer: Spread the prepared epoxy fully recycled mixture on the lower layer to a thickness of 5cm and compact it immediately; Top layer: Lay epoxy recycled mixture with a thickness of 4cm, compact and level it. Example 3:

[0036] This embodiment provides an epoxy fully recycled pavement structure and its preparation method, the specific steps of which are as follows: (1) The raw material preparation process is as follows: Recycled Asphalt Pavement (RAP): Old asphalt pavement materials are milled and recycled on-site. After being screened by vibration, RAP aggregates with a particle size of 5~25mm are selected, placed in a heated drum, and dried at 148℃ until there are no water marks on the surface, and then set aside for use. Epoxy Regenerator: By weight percentage, 36% bisphenol A type epoxy resin, 32% epoxy-modified aromatic amine composite curing agent, 22% hydroxyl-terminated polyether polyol toughening agent, and 10% epoxy propyl ether reactive diluent are used for preparation. First, the bisphenol A type epoxy resin and the hydroxyl-terminated polyether polyol toughening agent are stirred and mixed at 82℃ and 220 rpm for 19 minutes. Then, the epoxy-modified aromatic amine composite curing agent is added, and the mixture is stirred continuously at the same temperature for 10 minutes. Then, the system temperature is lowered to 52℃, the reactive diluent is slowly added, and the mixture is stirred for another 32 minutes. After vacuum degassing for 11 minutes, 6.0 parts by weight of homogeneous epoxy regenerator are obtained. The regenerator is placed in a storage tank and heated and kept at 122℃ for later use. Bio-based modified bitumen: Castor oil-based bio-bitumen (25% of the total mass) and base bitumen heated to a fluid state were added to a mixing tank and sheared and stirred at 450 rpm for 25 minutes at 175°C to form 3.8 parts by weight of homogeneous and stable bio-based modified bitumen, which was then heated and kept at 122°C for later use. Nano-reinforcing material: Take 0.6 parts by weight of graphene-modified montmorillonite with a layer spacing of 2.5 nm and a graphene loading of 2.5%, and 0.3 parts by weight of amine-functionalized carbon nanotubes with a tube diameter of 28 nm, a length of 2 μm, and an amine grafting rate of 5.0%, mix them evenly by dry method in advance, and put them into the dry powder metering silo for later use. (2) The surface layer of the epoxy fully recycled mixture is prepared using a closed mixing pot. The specific steps are as follows: Q1. Add 92 parts by weight of dried and prepared RAP into the mixing pot and pre-stir for 12 seconds to make the aggregate evenly distributed. Q2 Add 6.0 parts by weight of epoxy recycling agent at 122℃ to the mixing pot, maintain the mixing system temperature at 138℃, and stir at a constant speed for 33 seconds to allow the recycling agent to fully penetrate and activate the aged asphalt on the RAP surface. Q3 is then added with 3.8 parts by weight of bio-based modified asphalt at 122°C, and stirred for another 22 seconds to promote the fusion of the new and old asphalt and the coating of aggregates. Q4 Finally, add the premixed graphene-modified montmorillonite and amine-functionalized carbon nanotube dry powder mixture, stir and disperse for 72 seconds to ensure that the nanomaterials are evenly distributed in the asphalt binder; continue stirring for 22 seconds to obtain a uniform epoxy fully recycled mixture, and control the discharge temperature at 134~138℃.

[0037] (3) The RAP content of the epoxy recycled mixture is 45% of the weight of the intermediate layer RAP, i.e., 41 parts by weight. The remaining component proportions and preparation methods are the same as those of the intermediate layer.

[0038] (4) On the treated and compacted foundation, the epoxy fully recycled pavement structure of the present invention is laid in the following order: Lower layer: Cement-stabilized crushed stone is spread and compacted to a thickness of 10cm as a support layer; Intermediate layer: Spread the prepared epoxy fully recycled mixture on the lower layer to a thickness of 7cm and compact it immediately; Top layer: Lay epoxy recycled mixture with a thickness of 3cm, compact and level it.

[0039] Comparative Example 1: Unlike Example 1, this comparative example omits the addition of epoxy regenerator.

[0040] Comparative Example 2: Unlike Example 1, this comparative example does not include graphene-modified montmorillonite and amine-functionalized carbon nanotubes.

[0041] Comparative Example 3: Unlike Example 1, this comparative example increases the amount of RAP in the top layer to the same as that in the middle layer, i.e., 90 parts by weight of RAP.

[0042] Comparative Example 4: Unlike Example 1, this comparative example does not add hydroxyl-terminated polyether polyol toughening agent to the epoxy regenerator, but only uses the above-mentioned epoxy curing agent and diluent.

[0043] The pavement structures prepared in the examples and comparative examples were subjected to the following tests, and the data in Table 1 were obtained: The resilient modulus was determined using the bearing plate method, with reference to the standard JTG E60-2008. The dynamic modulus was obtained by uniaxial compression test, with reference standard AASHTO T 342. Fatigue life was determined using a four-point bending fatigue test. (Strain level), reference standard is AASHTO T321; The structural depth was tested using the sand-laying method, with reference to the standard JTG E60-2008 T 0961. The coefficient of friction was determined using the pendulum tester method, with reference standard JTG E60-2008 T 0964.

[0044] Table 1: Test Results of Examples and Comparative Examples As shown in Table 1, the epoxy fully recycled pavement structure provided by the present invention, as demonstrated by the test data of Examples 1-3, exhibits excellent and stable comprehensive performance. The synergistic effect of the three-layer functionalized structure and the targeted activation and interface enhancement material system enables the pavement to achieve high levels in key indicators such as resilience modulus, dynamic modulus, fatigue life, and surface function. This verifies that the present invention can meet the performance requirements of each structural layer of the pavement while achieving high RAP content recycling. In Comparative Example 1, because no epoxy recycling agent was added, the cross-linking network of the aged asphalt could not be chemically broken, and the old and new asphalt could not fully fuse. This resulted in insufficient integrity and load-bearing capacity of the cementing system, leading to... The fatigue life under strain level was significantly reduced, and the dynamic stability and low-temperature beam bending performance deteriorated significantly. Comparative Example 2 did not add graphene-modified montmorillonite and amino-functionalized carbon nanotubes. The asphalt-aggregate interface lacked nanoscale physical interlocking and chemical bonding enhancement, the stress dispersion effect was weakened, the material's crack resistance and durability were limited, and the fatigue life, dynamic stability and low-temperature beam bending failure strain all decreased significantly. Comparative Example 3 increased the RAP content of the top layer to the same as the middle layer. The proportion of new asphalt and functional components in the surface layer that could form a dense anti-skid structure was relatively insufficient, the pavement macro texture and friction coefficient decreased, and the dynamic stability and beam bending performance were slightly reduced. Comparative Example 4 did not contain hydroxyl-terminated polyether polyol toughening agent in the epoxy regenerator. The cured network lacked flexible chain segment interpenetration, the binder brittleness increased, the ability to resist repeated load deformation decreased, the fatigue life was significantly shortened, and the dynamic stability and low-temperature beam bending failure strain were significantly reduced.

[0045] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. An epoxy fully recycled pavement structure, characterized in that, The road structure, from bottom to top, consists of a lower layer composed of asphalt mixture or cement-stabilized crushed stone, an intermediate layer composed of epoxy fully recycled mixture, and an upper layer composed of epoxy recycled mixture. By weight, the epoxy fully recycled mixture comprises: 85-95 parts of recycled old asphalt pavement material, 5-10 parts of epoxy recycling agent, 3-6 parts of bio-based modified asphalt, 0.3-1.2 parts of graphene-modified montmorillonite, and 0.2-0.6 parts of amine-functionalized carbon nanotubes. In the top layer, the amount of recycled asphalt pavement material is 40-60% of that used in the middle layer.

2. The epoxy fully recycled pavement structure according to claim 1, characterized in that, The epoxy regenerator comprises, by weight percentage: 25-40% bisphenol A type epoxy resin, 30-50% epoxy modified aromatic amine composite curing agent, 15-35% hydroxyl-terminated polyether polyol toughening agent, and 5-15% epoxy propyl ether reactive diluent.

3. The epoxy fully recycled pavement structure according to claim 1, characterized in that, The bio-based modified asphalt is a composite modified product of castor oil-based bio-asphalt and base asphalt, wherein the amount of castor oil-based bio-asphalt accounts for 15-30% of the total mass of the bio-based modified asphalt.

4. The epoxy fully recycled pavement structure according to claim 1, characterized in that, The interlayer spacing of the graphene-modified montmorillonite is 2.0~3.5 nm, and the loading of graphene in montmorillonite is 1.5~3.0%.

5. The epoxy fully recycled pavement structure according to claim 1, characterized in that, The amine-functionalized carbon nanotubes have a diameter of 20-50 nm, a length of 1-5 μm, and an amine grafting rate of 3.2-5.8%.

6. The epoxy fully recycled pavement structure according to claim 2, characterized in that, The preparation method of the epoxy regenerator includes: S1. Bisphenol A type epoxy resin and hydroxyl-terminated polyether polyol toughening agent are mixed evenly at 80~90℃; S2 Add epoxy-modified aromatic amine composite curing agent to the mixture in step S1 and continue stirring at the same temperature; After mixing with S3, the temperature is lowered to 50~60℃, and epoxy propyl ether reactive diluent is slowly added. After mixing and vacuum degassing, epoxy regenerator is obtained.

7. The epoxy fully recycled pavement structure according to claim 6, characterized in that, The preparation method of the epoxy fully recycled mixture includes: Q1 The old asphalt pavement material milled on site is screened by vibration to obtain the old asphalt pavement recycled material, which is then heated and dried at 140~150℃ for later use. Q2 Weigh out the epoxy regenerator and bio-based modified asphalt, heat them separately to 120~130℃ and keep them warm for later use; premix the graphene-modified montmorillonite with the amine-functionalized carbon nanotubes for later use. Q3 Pre-stir the heated recycled asphalt pavement for 10-20 seconds; then add the epoxy recycling agent, maintain the temperature at 135-145℃, and stir for 30-40 seconds; then add the bio-based modified asphalt and continue stirring for 20-30 seconds. Q4 Then add the premixed graphene-modified montmorillonite and amine-functionalized carbon nanotubes, stir and disperse to obtain the epoxy fully recycled mixture.

8. The epoxy fully recycled pavement structure according to claim 7, characterized in that, The epoxy fully recycled mixture is prepared under closed conditions.

9. The epoxy fully recycled pavement structure according to claim 7, characterized in that, The particle size of the recycled old asphalt pavement is 5~25mm.

10. The application of the epoxy fully recycled pavement structure according to claims 1 to 9 in the reconstruction and expansion of high-grade highways and the maintenance and renovation of old pavements.

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