A regenerated asphalt concrete and its preparation method

Abstract

This application relates to the field of road construction materials, and specifically discloses a recycled asphalt concrete and its preparation method. The recycled asphalt concrete comprises the following raw materials: waste asphalt mixture, base asphalt, aggregate, mineral powder, hydroxyl-modified polyester fiber, polymer composite modifier, modified nano-silica, and recycling agent. The preparation method comprises the following steps: preheating the waste asphalt mixture; mixing and preheating the aggregate and the mineral powder; preheating the base asphalt and mixing it with the preheated aggregate to obtain a preliminary mixture; preheating the recycling agent and mixing it with the preliminary mixture, and then mixing and stirring it with the preheated waste asphalt mixture to obtain a mixture; mixing the hydroxyl-modified polyester fiber, the polymer composite modifier, and the modified nano-silica, and then mixing and stirring them with the mixture to obtain the recycled asphalt concrete. This application has the characteristics of alleviating the problem of late cracking of the recycled asphalt concrete to improve the durability of the recycled asphalt concrete.

Description

Technical Field

[0001] The present application relates to the field of road construction materials, and more specifically, to a recycled asphalt concrete and a preparation method thereof. Background Art

[0002] With the acceleration of my country's urbanization and the continuous improvement of transportation infrastructure, demand for asphalt concrete, a primary material for road paving, has increased annually. However, the production of traditional asphalt concrete requires a significant amount of natural sand and gravel, leading to over-exploitation of resources and severe environmental damage. To promote green building and a circular economy, recycled asphalt concrete mixtures have emerged.

[0003] Recycled asphalt concrete technology is a technology that recycles and processes old asphalt pavement materials and uses them in the preparation of new asphalt concrete. This technology realizes the reuse of resources and is in line with my country's sustainable development strategy. It can make full use of old asphalt pavement materials and reduce dependence on new materials. By recycling and reusing waste asphalt concrete, it can reduce resource waste and environmental pollution, and has important economic benefits and social significance.

[0004] Recycled asphalt concrete technology has been widely applied and developed in my country. Currently, the scale of road construction in my country is expanding year by year, creating a huge demand for asphalt concrete mixtures. Although recycled asphalt concrete, produced through recycling, crushing, screening, adding regenerants, and mixing, has similar performance to virgin asphalt concrete and can be widely used in highway and urban road construction, several practical issues remain that need to be addressed. For example, recycled asphalt concrete contains a certain proportion of aged asphalt, which reduces the lightweight components of aged asphalt and increases the asphaltene content. This reduces the asphalt's low-temperature crack resistance, making it more susceptible to cracking in later stages and less durable than brand-new asphalt concrete. Summary of the Invention

[0005] In order to alleviate the late cracking problem of recycled asphalt concrete and to improve the durability of recycled asphalt concrete, the present application provides a recycled asphalt concrete and a preparation method thereof.

[0006] In the first aspect, the present application provides a recycled asphalt concrete, which adopts the following technical solution:

[0007] A regenerated asphalt concrete comprises the following raw materials in parts by weight: 80-100 parts of waste asphalt mixture, 10-18 parts of base asphalt, 20-30 parts of aggregate, 5-12 parts of mineral powder, 8-15 parts of hydroxyl-modified polyester fiber, 12-18 parts of polymer composite modifier, 3-8 parts of modified nano-silica and 3-8 parts of regenerating agent;

[0008] Among them, the polymer composite modifier includes SBS powder and porous acrylate copolymer with a mass ratio of 1:(0.6 - 0.8). The modified nano-silica is obtained by impregnating nano-silica in an impregnating solution containing polyisopropylacrylamide, sodium polystyrene sulfonate, glutamic acid and 2-aminobenzoic acid.

[0009] By adopting the above technical solution, in this application, waste asphalt concrete is used as the main material, and matrix asphalt and new aggregates are additionally added. The matrix asphalt acts as a binder and cooperates with the new aggregates and waste asphalt concrete to form asphalt concrete. The addition of the regenerant can supplement the lost light components to the aged asphalt in the waste asphalt concrete, penetrate and dissolve the asphaltene in the aged asphalt, thereby restoring the viscosity and ductility of the asphalt and other indicators, making it regain the use performance similar to that of new asphalt, improving the anti-aging performance of the asphalt and its durability. Moreover, polyester fiber is also added in this application. On the one hand, the addition of polyester fiber can increase the toughness of the asphalt concrete, improve its crack resistance performance, keep it flexible and have a high tensile strength at low temperatures, so as to effectively resist the shrinkage stress and reduce the generation of temperature shrinkage cracks; and the three-dimensional distribution and strong adsorption performance of polyester fiber increase the cohesion of the asphalt, which can not only form a criss-cross reinforcing and bridging effect in the concrete, effectively improve the high-temperature stability of the recycled concrete, but also enhance the ability of the interfacial film formed between the asphalt and the aggregates in the asphalt concrete to resist the moisture stripping effect, thereby further improving the late crack resistance performance of the concrete and enhancing its durability performance.

[0010] In this application, a polymer composite modifier is added. The addition of SBS powder in the polymer composite modifier can interact with the resin in the asphalt to form a relatively stable bond. The cooperation of the waste asphalt concrete and the regenerant enables SBS to not only crosslink with the new matrix asphalt but also restore the crosslinking between the asphalt and SBS in the waste asphalt concrete, so that the performance of the waste asphalt concrete can be as close as possible to the original asphalt level. Moreover, the interaction between SBS and the asphalt can enhance the adhesion to the aggregate, so that the recycled asphalt concrete can still maintain a stable structure under high-temperature conditions. And SBS-modified asphalt has a relatively high glass transition temperature, which can maintain flexibility and elasticity at low temperatures, significantly improving its performance at low temperatures, thereby reducing the phenomenon of pavement cracking caused by temperature changes.

[0011] In addition, modified nano-silica and porous acrylate copolymer are also added to the raw materials of this application. When the modified nano-silica is added to the recycled asphalt concrete, it has nano-size effect and high specific surface area, which can significantly improve the mechanical properties and durability of the asphalt material. Moreover, it can be evenly dispersed in the asphalt matrix to form a nano-scale reinforcing phase, significantly improving the elastic modulus and crack resistance of the asphalt, reducing cracks and damages on the road surface. After being impregnated in an impregnating solution containing polyisopropylacrylamide, sodium polystyrene sulfonate, glutamic acid, etc., the nano-silica realizes the loading of polyisopropylacrylamide. As a thermosensitive material, it absorbs water and expands in volume when the temperature rises, and releases water and shrinks in volume when the temperature drops, so that the internal stress state of the concrete can be adjusted when the temperature changes, thereby reducing crack generation and improving the durability of the concrete.

[0012] 2-Aminobenzoic acid contains amino group, carboxyl group and benzene ring. It realizes the interaction with the hydroxyl groups on the surface of nano-silica through the amino group or carboxyl group, thereby introducing the benzene ring group. The introduction of the benzene ring group helps to improve the compatibility between nano-silica and asphalt, and also helps to improve the temperature resistance performance and relieve the cracking caused by temperature shrinkage. The addition of sodium polystyrene sulfonate and glutamic acid, on the one hand, due to the negative charge of the sulfonic acid group, the sodium polystyrene sulfonate molecules are adsorbed on the surface of nano-silica with positive charge or adsorption sites on the surface, so that the surface of nano-silica is covered by sodium polystyrene sulfonate molecules, forming a steric hindrance effect, thereby reducing the aggregation of nano-silica and improving its uniform dispersion in asphalt concrete, which can play a better strengthening role. On the other hand, the sulfonic acid group in sodium polystyrene sulfonate can also form electrostatic interaction and chemical bonding with amino groups such as 2-aminobenzoic acid and glutamic acid to form sulfonamide bonds. The carboxyl groups in glutamic acid and 2-aminobenzoic acid can also form chemical interaction with the hydroxyl groups in the hydroxyl-modified polyester fiber. In this way, the polymer composite modifier forms a macromolecular network structure with polyester fiber and nano-silica, etc., further realizing the crack resistance of asphalt concrete and improving its durability. Moreover, the aggregation of modified nano-silica is reduced through the steric hindrance effect, and the introduced benzene ring improves the compatibility with asphalt, improving the mechanical properties and durability of the final asphalt concrete.

[0013] On the one hand, the addition of the porous acrylate copolymer helps the mutual adhesion between the aggregate and the asphalt by virtue of its bonding property, contributing to reducing the generation and expansion of cracks in the recycled asphalt concrete during the stress application process. On the other hand, the acrylate copolymer itself has high flexibility, which can absorb and disperse the stress generated by external forces on the recycled asphalt concrete. Moreover, the formation of the pore structure in the acrylate copolymer can achieve the function of water storage and drainage to a certain extent. In this way, it can cooperate with the thermosensitive substance polyisopropylacrylamide to adjust the stress and reduce the cracking phenomenon caused by thermal shrinkage, improving the crack resistance and durability of the recycled asphalt concrete.

[0014] Optionally, the impregnating solution comprises the following raw materials in parts by weight:

[0015] 10 - 20 parts of polyisopropylacrylamide, 3 - 8 parts of sodium polystyrene sulfonate, 2 - 5 parts of glutamic acid, 6 - 10 parts of 2 - aminobenzoic acid, 15 - 20 parts of methanol and 8 - 15 parts of water.

[0016] Optionally, the modified nano - silica is prepared by the following method:

[0017] Mix polyisopropylacrylamide, sodium polystyrene sulfonate, glutamic acid and 2 - aminobenzoic acid with methanol and water, heat up to 45 - 50 °C, stir until completely dissolved, then add nano - silica under stirring, stir and pressurize to 0.4 - 0.6 MPa, and then filter and dry after impregnation treatment for 20 - 30 min to obtain the modified nano - silica.

[0018] By adopting the above - mentioned technical solution, carrying out impregnation modification under the temperature and pressure conditions in the present application helps to promote the better penetration of the modifier molecules in the impregnating solution into the micropores on the surface of the nano - silica, enhancing the interaction between the modifier and the nano - silica.

[0019] Optionally, the porous acrylate copolymer is prepared by the following method:

[0020] 1), Mix γ - methacryloxypropyltrimethoxysilane, solvent A and graphene aerogel, impregnate and then dry to obtain the pretreated aerogel;

[0021] 2), Mix acrylate monomers, sodium polystyrene sulfonate, triethanolamine, acrylamide, initiator, cross - linker, stabilizer, toluene and solvent B to obtain a reaction solution, then add the pretreated aerogel prepared in step 1), and polymerize at 80 - 90 °C for 2 - 4 h to obtain the acrylate copolymer.

[0022] By adopting the above technical solution, in the present application, γ-methacryloxypropyltrimethoxysilane is first used to pretreat the graphene aerogel. The trimethoxysilyl group in γ-methacryloxypropyltrimethoxysilane hydrolyzes to generate silanol groups, which react with the graphene aerogel containing hydroxyl groups to form siloxane bonds, thereby realizing the introduction of unsaturated double bond groups on the surface of the graphene aerogel. Then, after mixing with the reaction solution, under the action of an initiator, the double bond unsaturated groups react with monomers such as acrylate monomers and acrylamide to carry out in-situ polymerization with the graphene aerogel as the framework to form an acrylate resin. The addition of toluene in the reaction solution realizes the establishment of the pore structure of the acrylate copolymer. Finally, an acrylate resin with a graphene aerogel as the framework structure and formed by in-situ polymerization is prepared. The graphene aerogel itself has the characteristic of a high specific surface area, with a large number of micropores and hollow structures. Combined with the addition of a pore-forming agent during in-situ polymerization to form a pore-structured acrylate resin, the formation of the pore structure helps to absorb and disperse stress, resist the damage of external stress, thereby delaying the generation and expansion of cracks and reducing the risk of crack generation. On the other hand, the establishment of the porous structure can slow down the thermal expansion and contraction of the material, reduce cracks caused by thermal contraction, and moreover, functional monomers such as sulfonic acid groups are introduced during the combination process, endowing it with a certain water storage function. Combined with a thermosensitive material, it can further resist cracking caused by thermal expansion and contraction and improve its durability.

[0023] Optionally, during the preparation of the porous acrylate copolymer, the raw materials are added in the following parts by weight: 3 - 7 parts of γ-methacryloxypropyltrimethoxysilane, 30 - 40 parts of solvent A, 25 - 35 parts of graphene aerogel, 40 - 50 parts of acrylate monomer, 10 - 20 parts of sodium styrene sulfonate, 5 - 12 parts of triethanolamine, 12 - 22 parts of acrylamide, 2 - 6 parts

[0024] of initiator, 1 - 3 parts of crosslinking agent, 1 - 3 parts of stabilizer, 5 - 10 parts of toluene, 40 - 50 parts of solvent B.

[0025] By adopting the above technical solution, the introduction of the sulfonic acid group in sodium styrene sulfonate in the present application realizes the adjustment of the hydrophilic group of the acrylate copolymer, and also introduces a benzene ring group, improving its compatibility with the asphalt matrix in the present application. The introduction of hydroxyl and amino functional groups in triethanolamine and acrylamide helps the chemical bonding with modified nano-silica and hydroxyl-modified polyester fibers, and finally realizes the chemical entanglement of the above substances to form a more compact and firm network structure, which helps to form microcracks subsequently and improve the durability.

[0026] Optionally, the stabilizer is selected from polyvinylpyrrolidone or polyethylene glycol;

[0027] The acrylate monomer is selected from one or more of methyl methacrylate, ethyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate;

[0028] The initiator is selected from one or two of benzoyl peroxide and azobisisobutyronitrile;

[0029] The crosslinking agent is selected from one or two of ethylene glycol dimethacrylate and trimethylolpropane triacrylate.

[0030] Optionally, in step 1), the solvent A is a mixture of methanol and water with a mass ratio of 1:(1.5 - 2);

[0031] The solvent B in step 2) is a mixture of water and sodium dodecyl sulfate with a mass ratio of 1:(0.1 - 0.2).

[0032] Optionally, the hydroxyl - modified polyester fiber is prepared by the following method:

[0033] Mix polyester fiber scraps and glass fiber according to a mass ratio of 1:(0.1 - 0.2) to obtain mixed fiber, then soak the mixed fiber in hydrogen peroxide. The soaking temperature is 50 - 60 °C. After soaking for 10 - 20 min, add 2 - hydroxyethyl acrylate and methyl methacrylate, react at 65 - 75 °C for 1 - 2 h, then cool, filter, wash with water and dry to obtain the hydroxyl - modified polyester fiber.

[0034] By adopting the above technical solution, in this application, the mixed fiber is first soaked in hydrogen peroxide. Hydrogen peroxide, as an oxidant, initiates the surface oxidation reaction of the polyester fiber, generating free - radical sites. These free - radical sites have high reactivity and can undergo an addition reaction with the double bonds in the monomer to achieve monomer grafting. Then, after adding 2 - hydroxyethyl acrylate and methyl methacrylate, the hydroxyl functional group in 2 - hydroxyethyl acrylate reacts with the free radicals on the surface of the polyester fiber, thereby introducing hydroxyl groups into the polyester fiber. The methyl methacrylate and 2 - hydroxyethyl acrylate form a copolymer chain segment containing hydroxyl groups through copolymerization reaction and further react with the surface active sites of the polyester fiber, making the hydroxyl groups grafted more firmly on the fiber, realizing the hydroxyl modification of the polyester fiber.

[0035] Optionally, during the preparation of the hydroxyl - modified polyester fiber, the mass ratio of the added mixed fiber to hydrogen peroxide is 1:(1 - 2), and hydrogen peroxide and water are mixed according to a mass ratio of 1:(3 - 4) and then used to soak the mixed fiber. The mass ratio of the added mixed fiber to 2 - hydroxyethyl acrylate and methyl methacrylate is 1:(0.4 - 0.5):(0.1 - 0.2).

[0036] Optionally, the regenerant includes mesophase pitch, tung oil, penetrant, light stabilizer and antioxidant with a mass ratio of 1:(1.5 - 2):(0.05 - 0.1):(0.05 - 0.1):(0.05 - 0.1).

[0037] By adopting the above technical solution, on the basis of tung oil in the regenerant of the present application, mesophase pitch is further added. The mesophase pitch contains aromatic hydrocarbons and unsaturated double bonds. The addition of the above mesophase pitch introduces unsaturated double bonds and aromatic hydrocarbons. On the one hand, it helps to dissolve waste asphalt, and on the other hand, it can enhance the adhesion and consistency of asphalt mixture. Moreover, the above substances can also react with the oxidized substances in waste asphalt to realize the regeneration of asphalt. Especially the introduction of hydroxyl and amino groups in modified silica and polymer modifier in the present application, as reducing functional groups, helps to restore the performance of asphalt, and can also chemically react with the oxidized substances in waste asphalt to improve its molecular structure and realize asphalt regeneration. Finally, the performance of the prepared recycled asphalt concrete is better.

[0038] Optionally, the base asphalt is selected from one or more of petroleum asphalt and natural asphalt;

[0039] The aggregate is selected as slag and crushed stone with a mass ratio of 1:(2 - 3), and the crushed stone is selected as crushed stone with a continuous particle size of 5 - 15 mm.

[0040] Optionally, the antioxidant is selected as 2,2 - methylenebis(4 - methyl - 6 - tert - butylphenol);

[0041] The light stabilizer is selected as a hindered amine light stabilizer;

[0042] The penetrant is selected as alkylphenol polyoxyethylene ether.

[0043] By adopting the above technical solution, the hindered amine light stabilizer helps to improve the anti - photo - aging performance of recycled asphalt and extend its service life. Alkylphenol polyoxyethylene ether has excellent permeability and surface activity, which not only helps to improve the miscibility of the regenerant and waste asphalt mixture to realize the regeneration of waste asphalt, but also helps to improve the miscibility of waste asphalt and new asphalt.

[0044] In the second aspect, the present application provides a preparation method of recycled asphalt concrete, adopting the following technical solution:

[0045] A preparation method of recycled asphalt concrete includes the following steps:

[0046] S1. Preheat the waste asphalt mixture at 110 - 130 °C for 10 - 20 min to obtain a preheated waste asphalt mixture;

[0047] Preheat the aggregate and mineral powder after mixing at 120 - 150 °C for 5 - 10 min to obtain preheated aggregate;

[0048] S2. Preheat the matrix asphalt at 140 - 160 °C for 5 - 10 min and then mix it with the preheated aggregate to prepare a preliminary mixture;

[0049] S3. Preheat the regenerant at 110 - 120 °C for 3 - 8 min, mix it with the preliminary mixture, and then mix and stir it with the preheated waste asphalt mixture to obtain a mixture;

[0050] S4. Mix the hydroxy - modified polyester fiber, polymer composite modifier, and modified nano - silica, and then mix and stir it with the mixture to prepare recycled asphalt concrete.

[0051] By adopting the above technical solution, the method provided by this application is simple, convenient, and easy to realize industrialization.

[0052] In summary, this application has the following beneficial effects:

[0053] 1. The raw materials of this application are added with modified nano - silica and porous acrylate copolymer. When the modified nano - silica is added to recycled asphalt concrete, it has nano - size effect and high specific surface area, which can significantly improve the mechanical properties and durability of asphalt materials. Moreover, it can be uniformly dispersed in the asphalt matrix to form a nano - scale reinforcing phase, significantly improving the elastic modulus and anti - cracking performance of asphalt, reducing cracks and damages on the road surface; and after being impregnated in an impregnating solution containing polyisopropylacrylamide, sodium polystyrene sulfonate, glutamic acid, etc., the nano - silica realizes the loading of polyisopropylacrylamide. As a thermosensitive material, it absorbs water and expands in volume when the temperature rises, and releases water and contracts in volume when the temperature drops, so as to adjust the internal stress state of the concrete when the temperature changes, thereby reducing crack generation and improving the durability of the concrete;

[0054] 2. When the modified nano - silica is modified, 2 - aminobenzoic acid acts on the surface hydroxyl groups of nano - silica through amino or carboxyl groups, thereby introducing benzene rings. The introduction of benzene ring groups helps to improve the compatibility between nano - silica and asphalt, and also helps to improve the heat - resistant performance and relieve cracking caused by thermal shrinkage; the addition of sodium polystyrene sulfonate and glutamic acid reduces the agglomeration of nano - silica and improves its uniform dispersion in asphalt concrete, which can play a better strengthening role, and enables the polymer composite modifier, polyester fiber, and nano - silica to form a macromolecular network structure, further realizing the anti - cracking performance of asphalt concrete and improving its durability. Moreover, the steric hindrance effect in the modified nano - silica reduces its agglomeration, and the introduced benzene ring improves the compatibility with asphalt, improving the mechanical properties and durability of the final asphalt concrete;

[0055] 3. In this application, on the one hand, the addition of the porous acrylate copolymer helps the mutual adhesion performance between the aggregate and the asphalt by virtue of its bonding performance, which helps to reduce the generation and expansion of cracks in the recycled asphalt concrete during the stress process. On the other hand, the acrylate copolymer itself has high flexibility, which can absorb and disperse the stress generated by the external force on the recycled asphalt concrete. Moreover, the formation of the pore structure in the acrylate copolymer can achieve the function of storing and discharging water to a certain extent. In this way, it can cooperate with the thermosensitive substance polyisopropylacrylamide for stress regulation to reduce the cracking phenomenon caused by temperature shrinkage, and improve the crack resistance and durability of the recycled asphalt concrete. Detailed implementation manners

[0056] The following further elaborates on this application in conjunction with the embodiments. It should be specifically noted that: for those conditions not specified in the following embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Except for special instructions, the raw materials used in the following embodiments can all be obtained from ordinary commercial sources.

[0057] In the following preparation examples, the graphene aerogel is the graphene aerogel with the brand of Beijing University of Science and Technology Nano and the model of BK2020062720 produced by Suzhou Kaifa New Materials Technology Co., Ltd.

[0058] The following Preparation Examples 1-4 are the preparation examples of the porous acrylate copolymer, Preparation Examples 5-9 are the preparation examples of the modified nano-silica, and Preparation Examples 10-13 are the preparation examples of the hydroxyl-modified polyester fiber.

[0059] Preparation Example 1

[0060] A preparation method of a porous acrylate copolymer includes the following steps:

[0061] 1), Mix 5 kg of γ-methacryloxypropyltrimethoxysilane, 35 kg of Solvent A and 30 kg of graphene aerogel, impregnate for 35 min and then dry to obtain a pretreated aerogel, and the impregnation temperature is 45 °C;

[0062] 2), Mix 45 kg of acrylate monomer, 15 kg of sodium styrenesulfonate, 8 kg of triethanolamine, 15 kg of acrylamide, 5 kg of initiator, 2 kg of crosslinking agent, 2 kg of stabilizer, 8 kg of toluene and 45 kg of Solvent B to obtain a reaction solution, and then add the pretreated aerogel prepared in step 1), and polymerize at 85 °C for 3 h to obtain an acrylate copolymer.

[0063] Among them, the stabilizer is polyvinylpyrrolidone; the acrylate monomer is ethyl acrylate; the initiator is benzoyl peroxide; the crosslinking agent is ethylene glycol dimethacrylate; the solvent A is a mixture of methanol and water with a mass ratio of 1:1.8; the solvent B is a mixture of water and sodium dodecyl sulfate with a mass ratio of 1:0.1.

[0064] Preparation Example 2

[0065] A method for preparing a porous acrylate copolymer, comprising the following steps:

[0066] 1), Mix 3 kg of γ-methacryloxypropyltrimethoxysilane, 30 kg of solvent A and 25 kg of graphene aerogel, impregnate for 40 min and then dry to obtain a pretreated aerogel, and the impregnation temperature is 40 °C;

[0067] 2), Mix 40 kg of acrylate monomer, 10 kg of sodium styrenesulfonate, 5 kg of triethanolamine, 12 kg of acrylamide, 2 kg of initiator, 1 kg of crosslinking agent, 1 kg of stabilizer, 5 kg of toluene and 40 kg of solvent B to obtain a reaction solution, and then add the pretreated aerogel prepared in step 1), and polymerize at 80 °C for 4 h to obtain an acrylate copolymer.

[0068] Among them, the stabilizer is polyethylene glycol; the acrylate monomer is methyl methacrylate; the initiator is azobisisobutyronitrile; the crosslinking agent is trimethylolpropane triacrylate; the solvent A is a mixture of methanol and water with a mass ratio of 1:1.5; the solvent B is a mixture of water and sodium dodecyl sulfate with a mass ratio of 1:0.1.

[0069] Preparation Example 3

[0070] A method for preparing a porous acrylate copolymer, comprising the following steps:

[0071] 1), Mix 7 kg of γ-methacryloxypropyltrimethoxysilane, 40 kg of solvent A and 35 kg of graphene aerogel, impregnate for 30 min and then dry to obtain a pretreated aerogel, and the impregnation temperature is 50 °C;

[0072] 2), Mix 50 kg of acrylate monomer, 20 kg of sodium styrenesulfonate, 12 kg of triethanolamine, 22 kg of acrylamide, 6 kg of initiator, 3 kg of crosslinking agent, 3 kg of stabilizer, 10 kg of toluene and 50 kg of solvent B to obtain a reaction solution, and then add the pretreated aerogel prepared in step 1), and polymerize at 90 °C for 2 h to obtain an acrylate copolymer.

[0073] Among them, polyvinylpyrrolidone is selected as the stabilizer; isobutyl acrylate is selected as the acrylate monomer; benzoyl peroxide is selected as the initiator; ethylene glycol dimethacrylate is selected as the crosslinking agent; solvent A is a mixture of methanol and water with a mass ratio of 1:2; solvent B is a mixture of water and sodium dodecyl sulfate with a mass ratio of 1:0.2.

[0074] Preparation Example 4

[0075] A method for preparing a porous acrylate copolymer is carried out according to the method in Preparation Example 1, except that the operation of step 1) is not carried out, that is, graphene aerogel is not added in step 1).

[0076] Preparation Example 5

[0077] A method for preparing modified nano-silica includes the following steps:

[0078] Mix 15 kg of polyisopropylacrylamide, 5 kg of sodium polystyrene sulfonate, 3 kg of glutamic acid and 8 kg of 2-aminobenzoic acid with 18 kg of methanol and 12 kg of water, heat up to 50 °C, stir until completely dissolved to obtain an impregnating solution, then add nano-silica under stirring, stir and pressurize to 0.5 MPa, and then filter and dry after impregnation treatment for 25 min to obtain modified nano-silica. The added mass ratio of nano-silica to the impregnating solution is 1:7.

[0079] Preparation Example 6

[0080] A method for preparing modified nano-silica includes the following steps:

[0081] Mix 10 kg of polyisopropylacrylamide, 3 kg of sodium polystyrene sulfonate, 2 kg of glutamic acid and 6 kg of 2-aminobenzoic acid with 15 kg of methanol and 8 kg of water, heat up to 45 °C, stir until completely dissolved to obtain an impregnating solution, then add nano-silica under stirring, stir and pressurize to 0.4 MPa, and then filter and dry after impregnation treatment for 30 min to obtain modified nano-silica. The added mass ratio of nano-silica to the impregnating solution is 1:6.

[0082] Preparation Example 7

[0083] A method for preparing modified nano-silica includes the following steps:

[0084] Mix 20 kg of polyisopropylacrylamide, 8 kg of sodium polystyrene sulfonate, 5 kg of glutamic acid, and 10 kg of 2-aminobenzoic acid with 20 kg of methanol and 15 kg of water, heat up to 50 °C, stir until completely dissolved to obtain an impregnating solution, then add nano-silica under stirring, stir and pressurize to 0.6 MPa, then filter and dry after impregnation treatment for 20 min to obtain modified nano-silica. The added mass ratio of nano-silica to the impregnating solution is 1:8.

[0085] Comparative Preparation Example 1

[0086] A preparation method of modified nano-silica is carried out according to the method in Preparation Example 5, the difference is that 2-aminobenzoic acid is not added in the raw materials.

[0087] Comparative Preparation Example 2

[0088] A preparation method of modified nano-silica is carried out according to the method in Preparation Example 5, the difference is that sodium polystyrene sulfonate is not added in the raw materials.

[0089] The polyester fiber scraps in the following preparation examples are obtained by crushing waste yarns and the like generated during the processing of polyester fibers into textile products.

[0090] Preparation Example 8

[0091] A preparation method of hydroxyl-modified polyester fiber includes the following steps:

[0092] Mix polyester fiber scraps and glass fiber according to a mass ratio of 1:0.15 to obtain a mixed fiber, then soak the mixed fiber in hydrogen peroxide. The added mass ratio of the mixed fiber to hydrogen peroxide is 1:1.5, the soaking temperature is 55 °C. After soaking for 15 min, add hydroxyethyl acrylate and methyl methacrylate, react at 70 °C for 1.5 h, then cool, filter, wash with water and dry to obtain hydroxyl-modified polyester fiber. The added mass ratio of the mixed fiber to hydroxyethyl acrylate and methyl methacrylate is 1:0.45:0.15.

[0093] Preparation Example 9

[0094] A preparation method of hydroxyl-modified polyester fiber includes the following steps:

[0095] Polyester fiber scraps and glass fiber are mixed in a mass ratio of 1:0.1 to prepare mixed fibers, and then the mixed fibers are immersed in hydrogen peroxide, the added mass ratio of the mixed fibers to hydrogen peroxide is 1:1, the soaking temperature is 50°C, and after soaking for 20 minutes, hydroxyethyl acrylate and methyl methacrylate are added. After reacting at 65°C for 2 hours, the mixture is cooled, filtered, washed with water, and dried to prepare hydroxyl-modified polyester fibers, and the added mass ratio of the mixed fibers to hydroxyethyl acrylate and methyl methacrylate is 1:0.4:0.1.

[0096] Preparation Example 10

[0097] A method for preparing a hydroxyl-modified polyester fiber comprises the following steps:

[0098] Polyester fiber scraps and glass fiber are mixed in a mass ratio of 1:0.2 to prepare mixed fibers, and then the mixed fibers are immersed in hydrogen peroxide, the added mass ratio of the mixed fibers to hydrogen peroxide is 1:2, the soaking temperature is 60°C, and after soaking for 10 minutes, hydroxyethyl acrylate and methyl methacrylate are added. After reacting at 75°C for 1 hour, the mixture is cooled, filtered, washed with water, and dried to prepare hydroxyl-modified polyester fibers, and the added mass ratio of the mixed fibers to hydroxyethyl acrylate and methyl methacrylate is 1:0.5:0.2.

[0099] Preparation Example 11

[0100] A method for preparing a hydroxyl-modified polyester fiber is carried out according to the method in Preparation Example 10, except that methyl methacrylate is not added.

[0101] Example 1

[0102] A method for preparing regenerated asphalt concrete comprises the following steps:

[0103] S1. Preheating 90 kg of waste asphalt mixture at 120° C. for 15 minutes to obtain preheated waste asphalt mixture;

[0104] 25 kg of aggregate and 10 kg of mineral powder were mixed and preheated at 130 °C for 8 min to obtain preheated aggregate;

[0105] S2. Preheat 15 kg of base asphalt at 150° C. for 8 minutes and mix with the preheated aggregate to prepare a primary mix;

[0106] S3, preheating 5 kg of regeneration agent at 115° C. for 5 minutes, mixing the mixture with the primary mixture, and then mixing the mixture with the preheated waste asphalt mixture to obtain a mixture;

[0107] S4. 12 kg of hydroxyl-modified polyester fiber, 15 kg of polymer composite modifier and 5 kg of modified nano-silica are mixed and then stirred with the mixture to prepare recycled asphalt concrete.

[0108] Among them, in step S1, the waste asphalt mixture is obtained by crushing the asphalt pavement materials obtained by milling and then sieving, obtaining waste asphalt mixtures with particle sizes of 5-10 mm, 15-20 mm, and 25-30 mm. And the waste asphalt mixtures with particle sizes of 5-10 mm, 15-20 mm, and 25-30 mm are mixed in a ratio of 1:1.3:0.5 to obtain a waste asphalt mixture;

[0109] The aggregate is selected as slag and crushed stone with a mass ratio of 1:2.5. The crushed stone is selected as crushed stone with a continuous particle size of 5-15 mm; the mineral powder is selected as S95 mineral powder;

[0110] In step S2, the matrix asphalt is selected as petroleum asphalt, specifically Ⅶ0# road petroleum asphalt;

[0111] In step S3, the regenerant includes mesophase pitch, tung oil, penetrant, light stabilizer, and antioxidant with a mass ratio of 1:1.8:0.08:0.08:0.08. The antioxidant is selected as 2,2-methylenebis-(4-methyl-6-tert-butylphenol), the light stabilizer is selected as the hindered amine light stabilizer UV-622, and the penetrant is selected as alkylphenol polyoxyethylene ether, specifically octylphenol polyoxyethylene ether;

[0112] In step S4, the polymer composite modifier is obtained by mixing SBS powder (selecting SBS-792E from Jinan Shanhaichemical Technology Co., Ltd.) and the porous acrylate copolymer prepared in Preparation Example 1 in a mass ratio of 1:0.7. The modified nano-silica is selected as the modified nano-silica prepared in Preparation Example 5, and the hydroxyl-modified polyester fiber is selected as the hydroxyl-modified polyester fiber prepared in Preparation Example 8.

[0113] Example 2

[0114] A preparation method of recycled asphalt concrete, comprising the following steps:

[0115] S1. Preheat 80 kg of waste asphalt mixture at 110 °C for 20 min to obtain a preheated waste asphalt mixture;

[0116] Mix 20 kg of aggregate and 5 kg of mineral powder, and preheat at 120 °C for 10 min to obtain preheated aggregate;

[0117] S2. Preheat 10 kg of matrix asphalt at 140 °C for 10 min and then mix it with the preheated aggregate to obtain a preliminary mixture;

[0118] S3. Preheat 3 kg of regenerant at 110 °C for 3 min, mix it with the preliminary mixture, and then mix it with the preheated waste asphalt mixture and stir to obtain a mixture;

[0119] S4. Mix 8 kg of hydroxyl-modified polyester fiber, 12 kg of polymer composite modifier, and 3 kg of modified nano-silica, and then mix them with the mixture to obtain recycled asphalt concrete.

[0120] Among them, in step S1, the waste asphalt mixture is obtained by crushing the asphalt pavement materials obtained by milling and then screening, obtaining waste asphalt mixtures with particle sizes of 5 - 10 mm, 15 - 20 mm, and 25 - 30 mm, and the waste asphalt mixtures with particle sizes of 5 - 10 mm, 15 - 20 mm, and 25 - 30 mm are mixed in a ratio of 1:1.2:0.5 to obtain the waste asphalt mixture;

[0121] The aggregates are selected as slag and crushed stone with a mass ratio of 1:2, and the crushed stone is selected as crushed stone with a continuous particle size of 5 - 15 mm; the mineral powder is selected as S95 mineral powder;

[0122] In step S2, the matrix asphalt is selected as petroleum asphalt, specifically 70# road petroleum asphalt;

[0123] In step S3, the regenerant includes mesophase pitch, tung oil, penetrant, light stabilizer, and antioxidant with a mass ratio of 1:1.5:0.05:0.05:0.05. The antioxidant is selected as 2,2 - methylenebis-(4 - methyl - 6 - tert - butylphenol), the light stabilizer is selected as the hindered amine light stabilizer UV - 622, and the penetrant is selected as alkylphenol polyoxyethylene ether, specifically octylphenol polyoxyethylene ether;

[0124] In step S4, the polymer composite modifier is obtained by mixing SBS powder (selecting SBS - 792E from Jinan Shanhaichemical Technology Co., Ltd.) and the porous acrylate copolymer prepared in Preparation Example 2 in a mass ratio of 1:0.6. The modified nano - silica is selected as the modified nano - silica prepared in Preparation Example 6, and the hydroxyl - modified polyester fiber is selected as the hydroxyl - modified polyester fiber prepared in Preparation Example 9.

[0125] Example 3

[0126] A preparation method of recycled asphalt concrete, comprising the following steps:

[0127] S1. Preheat 100 kg of waste asphalt mixture at 130 °C for 10 min to obtain preheated waste asphalt mixture;

[0128] Mix 30 kg of aggregates and 12 kg of mineral powder, and preheat them at 150 °C for 5 min to obtain preheated aggregates;

[0129] S2. Preheat 18 kg of matrix asphalt at 160 °C for 5 min and then mix it with the preheated aggregates to obtain a preliminary mixture;

[0130] S3. Preheat 8 kg of the regenerant at 120°C for 3 min, then mix it with the premix, and then mix and stir it with the preheated waste asphalt mixture to obtain a mixture;

[0131] S4. Mix 15 kg of hydroxyl-modified polyester fiber, 18 kg of polymer composite modifier, and 8 kg of modified nano-silica, and then mix and stir them with the mixture to prepare the recycled asphalt concrete.

[0132] Among them, in step S1, the waste asphalt mixture is obtained by crushing the asphalt pavement materials obtained by milling and then sieving, to obtain waste asphalt mixtures with particle sizes of 5 - 10 mm, 15 - 20 mm, and 25 - 30 mm, and the waste asphalt mixtures with particle sizes of 5 - 10 mm, 15 - 20 mm, and 25 - 30 mm are mixed in a ratio of 1:1.5:0.6 to obtain the waste asphalt mixture;

[0133] The aggregates are selected as slag and crushed stone with a mass ratio of 1:3, the crushed stone is selected as crushed stone with a continuous particle size of 5 - 15 mm; the mineral powder is selected as S95 mineral powder;

[0134] In step S2, the matrix asphalt is selected as petroleum asphalt, specifically 70# road petroleum asphalt;

[0135] In step S3, the regenerant includes mesophase pitch, tung oil, penetrant, light stabilizer, and antioxidant with a mass ratio of 1:2:0.1:0.1:0.1. The antioxidant is selected as 2,2 - methylenebis-(4 - methyl - 6 - tert - butylphenol), the light stabilizer is selected as the hindered amine light stabilizer UV - 622, and the penetrant is selected as alkylphenol polyoxyethylene ether, specifically octylphenol polyoxyethylene ether;

[0136] In step S4, the polymer composite modifier is obtained by mixing SBS powder (selecting SBS - 792E from Jinan Shanha Chemical Technology Co., Ltd.) and the porous acrylate copolymer prepared in Preparation Example 3 in a mass ratio of 1:0.8. The modified nano - silica is selected as the modified nano - silica prepared in Preparation Example 7, and the hydroxyl - modified polyester fiber is selected as the hydroxyl - modified polyester fiber prepared in Preparation Example 10.

[0137] Example 4

[0138] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, the difference is that in step S4, the porous acrylic copolymer is selected as the porous acrylic copolymer in Preparation Example 4.

[0139] Example 5

[0140] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, the difference is that in step S4, the hydroxyl - modified polyester fiber is selected as the hydroxyl - modified polyester fiber prepared in Preparation Example 11.

[0141] Example 6

[0142] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that mesophase pitch is not added to the regenerant.

[0143] Comparative Example 1

[0144] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that the hydroxyl-modified polyester fiber is replaced with unmodified polyester fiber in equal amount in step S4.

[0145] Comparative Example 2

[0146] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that porous acrylate copolymer is not added to the polymer composite modifier.

[0147] Comparative Example 3

[0148] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that the modified nano-silica is replaced with nano-silica in equal amount.

[0149] Comparative Example 4

[0150] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that the modified nano-silica is replaced with a mixture of nano-silica and polyisopropylacrylamide at a mass ratio of 1:0.1.

[0151] Comparative Examples 5 - 6

[0152] A preparation method of recycled asphalt concrete is carried out according to the method in Example 1, except that the modified nano-silica in step S4 is respectively selected as the nano-silica prepared in Comparative Preparation Example 1 and Comparative Preparation Example 2.

[0153] Performance Detection

[0154] The freeze-thaw splitting strength ratio (%) of the recycled asphalt concrete prepared in the examples and comparative examples of this application is measured according to the method of T0729 - 2000 in JTJ052 - 2000 "Test Regulations for Asphalt and Asphalt Mixtures in Highway Engineering" to evaluate its low-temperature crack resistance, and the test results are shown in Table 1 below.

[0155] Table 1:

[0156]

[0157] Referring to the test results in Table 1 above, it can be seen that the recycled asphalt concrete prepared in the embodiments of the present application has excellent low-temperature crack resistance. Referring again to the test results of Example 1 and Example 4, when preparing the porous acrylic copolymer in Example 4 without adding graphene aerogel, its low-temperature crack resistance decreases. Combining with the test results of Example 5, during the preparation of the hydroxyl-modified polyester fiber, when only hydroxyl monomers are added without adding methyl methacrylate, its low-temperature crack resistance also decreases. The addition of methyl methacrylate helps the combination of hydroxyethyl acrylate and the active free radicals of the polyester fiber, improving its performance. Referring again to the test results of Example 6, it can be seen that when the rejuvenator does not contain mesophase pitch, its low-temperature crack resistance also decreases. The addition of mesophase pitch, with the addition of its aromatic hydrocarbons and unsaturated bonds, helps the regeneration of waste asphalt and improves its performance.

[0158] Combining with the test results of Example 1 and Comparative Example 1, when the polyester fiber in Comparative Example 1 is directly added without being hydroxyl-modified, its crack resistance also decreases. Hydroxyl modification helps to form a network structure with the polymer composite modifier and modified nano-silica, further improving its performance. Combining with the test results of Comparative Example 2, when the porous acrylate copolymer is not added, on the one hand, the adhesion performance of the asphalt is affected, and on the other hand, it cannot play a stress buffering role when subjected to external forces, and its low-temperature crack resistance is significantly reduced. Combining with the test results of Comparative Examples 3 and 4, when the nano-silica is added without modification, its performance is significantly reduced. When it is added together with the thermosensitive material without modification, although the addition of the thermosensitive material has a certain positive effect on crack resistance, it is still much weaker than that of Example 1. Combining with the test results of Comparative Examples 5 and 6, it can be seen that when the nano-silica is modified, without adding sodium polystyrene sulfonate or 2-aminobenzoic acid, its crack resistance is significantly reduced. The addition of the above-mentioned modifier substances not only helps to improve the compatibility of the nano-silica and the asphalt system, but also the introduction of functional groups such as sulfonic groups, amino groups, and carboxyl groups in cooperation with the rejuvenator affects the asphalt regeneration performance, and also affects the formation of a network molecular structure with polyester fibers in the system, thus playing a better crack resistance role.

[0159] In addition, for the recycled asphalt concrete prepared in Example 1 of the present application, the dynamic stability was measured according to T0719-2011 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2011), and the immersion Marshall residual stability (60°C) was measured according to T0709-2000 "Marshall Stability Test for Asphalt Mixtures". The measurement results are shown in Table 1 below.

[0160] Table 1:

[0161] Test items Dynamic stability (times / min) Immersion Marshall residual stability / % Example 1 6890 88

[0162] In the embodiments of the present application, the prepared recycled asphalt mixture also has excellent water stability and rutting resistance.

[0163] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A recycled asphalt concrete, characterized in that, Comprising the following raw materials in parts by weight: 80 - 100 parts of waste asphalt mixture, 10 - 18 parts of matrix asphalt, 20 - 30 parts of aggregate, 5 - 12 parts of mineral powder, 8 - 15 parts of hydroxyl - modified polyester fiber, 12 - 18 parts of polymer composite modifier, 3 - 8 parts of modified nano - silica, and 3 - 8 parts of regenerant; Among them, the polymer composite modifier includes SBS powder and porous acrylate copolymer with a mass ratio of 1:(0.6 - 0.8), and the modified nano - silica is obtained by impregnating nano - silica in an impregnating solution containing polyisopropylacrylamide, sodium polystyrenesulfonate, glutamic acid, and 2 - aminobenzoic acid; The porous acrylate copolymer is prepared by the following method: 1). Mix γ - methacryloxypropyltrimethoxysilane, solvent A, and graphene aerogel, impregnate and then dry to obtain a pretreated aerogel; 2). Mix acrylate monomers, sodium polystyrenesulfonate, triethanolamine, acrylamide, initiator, cross - linker, stabilizer, toluene, and solvent B to obtain a reaction solution, then add the pretreated aerogel prepared in step 1), and polymerize at 80 - 90 °C for 2 - 4 h to obtain an acrylate copolymer.

2. A recycled asphalt concrete according to claim 1, characterized in that: The impregnating solution comprises the following raw materials in parts by weight: 10 - 20 parts of polyisopropylacrylamide, 3 - 8 parts of sodium polystyrenesulfonate, 2 - 5 parts of glutamic acid, 6 - 10 parts of 2 - aminobenzoic acid, 15 - 20 parts of methanol, and 8 - 15 parts of water.

3. The recycled asphalt concrete according to claim 2, wherein: The modified nano - silica is prepared by the following method: Mix polyisopropylacrylamide, sodium polystyrenesulfonate, glutamic acid, 2 - aminobenzoic acid with methanol and water, heat up to 45 - 50 °C, stir until completely dissolved, then add nano - silica under stirring, stir and pressurize to 0.4 - 0.6 MPa, then impregnate for 20 - 30 min and filter and dry to obtain modified nano - silica.

4. A recycled asphalt concrete according to claim 1, characterized in that: During the preparation process of the porous acrylate copolymer, the raw materials are added according to the following parts by weight: 3 - 7 parts of γ - methacryloxypropyltrimethoxysilane, 30 - 40 parts of solvent A, 25 - 35 parts of graphene aerogel, 40 - 50 parts of acrylate monomers, 10 - 20 parts of sodium polystyrenesulfonate, 5 - 12 parts of triethanolamine, 12 - 22 parts of acrylamide, 2 - 6 parts of initiator, 1 - 3 parts of cross - linker, 1 - 3 parts of stabilizer, 5 - 10 parts of toluene, 40 - 50 parts of solvent B.

5. A recycled asphalt concrete according to claim 1, characterized in that: The stabilizer is selected from polyvinylpyrrolidone or polyethylene glycol; The acrylate monomers are selected from one or more of methyl methacrylate, ethyl acrylate, isobutyl acrylate, 2 - ethylhexyl acrylate; The initiator is selected from one or two of benzoyl peroxide and azobisisobutyronitrile; The cross - linker is selected from one or two of ethylene glycol dimethacrylate and trimethylolpropane triacrylate; Solvent A is a mixture of methanol and water with a mass ratio of 1:(1.5 - 2); Solvent B is a mixture of water and sodium dodecyl sulfate with a mass ratio of 1:(0.1 - 0.2).

6. A recycled asphalt concrete according to claim 1, characterized in that: The hydroxyl - modified polyester fiber is prepared by the following method: Mix polyester fiber scraps and glass fiber in a mass ratio of 1:(0.1 - 0.2) to obtain mixed fiber. Then soak the mixed fiber in hydrogen peroxide. The soaking temperature is 50 - 60°C. After soaking for 10 - 20 min, add hydroxyethyl acrylate and methyl methacrylate, react at 65 - 75°C for 1 - 2 h, then cool, filter, wash with water and dry to obtain hydroxyl-modified polyester fiber.

7. A recycled asphalt concrete according to claim 6, characterized in that: During the preparation process of the hydroxyl-modified polyester fiber, the added mass ratio of the mixed fiber to hydrogen peroxide is 1:(1 - 2), and hydrogen peroxide and water are mixed in a mass ratio of 1:(3 - 4) and then used to soak the mixed fiber. The added mass ratio of the mixed fiber to hydroxyethyl acrylate and methyl methacrylate is 1:(0.4 - 0.5):(0.1 - 0.2).

8. A recycled asphalt concrete according to claim 1, wherein: The regenerant includes mesophase pitch, tung oil, penetrant, light stabilizer and antioxidant in a mass ratio of 1:(1.5 - 2):(0.4 - 0.6):(0.05 - 0.1):(0.05 - 0.1):(0.05 - 0.1); The matrix asphalt is selected from one or more of petroleum asphalt and natural asphalt; The aggregate is selected as slag and crushed stone in a mass ratio of 1:(2 - 3). The crushed stone is crushed stone with a continuous particle size of 5 - 15 mm.

9. A method for preparing the recycled asphalt concrete according to any one of claims 1-8, characterized in that: It includes the following steps: S1. Preheat the waste asphalt mixture at 110 - 130°C for 10 - 20 min to obtain a preheated waste asphalt mixture; Mix the aggregate and mineral powder and preheat at 120 - 150°C for 5 - 10 min to obtain preheated aggregate; S2. Preheat the matrix asphalt at 140 - 160°C for 5 - 10 min and then mix it with the preheated aggregate to obtain a preliminary mixture; S3. Preheat the regenerant at 110 - 120°C for 3 - 8 min, mix it with the preliminary mixture, and then mix it with the preheated waste asphalt mixture and stir to obtain a mixture; S4. Mix the hydroxyl-modified polyester fiber, polymer composite modifier and modified nano-silica, and then stir and mix it with the mixture to obtain recycled asphalt concrete.

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