A hyperbranched aminyl rubber for ultra-thin overlays, modified bitumen, asphalt mixtures, and methods of making the same

Abstract

The present application belongs to the technical field of modified asphalt paving materials, and particularly relates to a hyperbranched aminogroup rubber for an ultrathin overlay, modified asphalt, asphalt mixture and a preparation method thereof. The hyperbranched aminogroup rubber is prepared from unsaturated amine, butadiene and ethylene derivatives under the action of a catalyst, and the yield can reach more than 85%. The hyperbranched aminogroup rubber is used for preparing modified asphalt, and SBS modifier, stabilizer, hyperbranched aminogroup rubber and rubber oil are added into base asphalt to obtain modified asphalt after shear development. The modified asphalt is used for preparing asphalt mixture of ultrathin overlay. The present application introduces hyperbranched aminogroup rubber for composite modification, significantly improves the high and low temperature performance, elasticity and anti-fatigue cracking capacity of asphalt binder, solves the problems of rutting, cracking, insufficient anti-sliding durability and the like of traditional ultrathin overlay mixture, and is particularly suitable for preventive maintenance and ultrathin overlay engineering of high-grade highways.

Description

Technical Field

[0001] This invention belongs to the technical field of modified asphalt pavement materials, specifically relating to a hyperbranched amine rubber, modified asphalt, asphalt mixture, and preparation method thereof for ultra-thin overlays. Background Technology

[0002] Currently, thin-layer overlay technology is gradually becoming mainstream. For example, Chinese patent CN119528489A discloses a cold-mix, cold-laid ultra-thin overlay asphalt mixture and its construction process. The asphalt mixture is made from the following raw materials by weight: 8-15 parts of rubber powder composite emulsified asphalt; 80-90 parts of aggregate; 0.3-0.5 parts of polymer fiber; and 0.5-1 parts of interface coupling agent. By using rubber powder from ground waste tires and SBS rubber to prepare a composite modified asphalt, which is then emulsified to obtain rubber powder composite emulsified asphalt, the performance indicators of the emulsified asphalt are greatly improved, ensuring the adhesion performance of the cold-mix thin-layer asphalt mixture to the original road surface. Furthermore, the addition of polymer fiber can significantly improve the structural strength and crack resistance of the ultra-thin overlay.

[0003] However, existing ultra-thin overlay asphalt materials still have the following technical problems: The binders of existing ultra-thin overlay asphalt mixtures, such as traditional high-viscosity or high-viscosity-high-elasticity modified asphalt, suffer from insufficient elasticity and difficulty in simultaneously achieving good high and low temperature performance and fatigue cracking resistance. This leads to rutting in summer and cracking in winter for the laid ultra-thin overlay layer. At the same time, existing ultra-thin overlay asphalt mixtures have poor frost heave resistance and suffer from insufficient crack resistance, easy dispersion, and peeling, seriously affecting road safety and service life. Therefore, developing a modified asphalt and its mixture technology with excellent high-temperature rutting resistance, low-temperature cracking resistance, high fatigue resistance, and excellent durability, applicable to ultra-thin overlay materials, is an urgent problem to be solved. Summary of the Invention

[0004] To address the technical problems of existing ultra-thin overlay materials, such as high-temperature rutting resistance, low-temperature cracking resistance, and poor durability, this invention provides a hyperbranched amine rubber, modified asphalt, asphalt mixture, and their preparation method for ultra-thin overlays. By synthesizing a novel hyperbranched amine rubber and utilizing its highly branched three-dimensional molecular structure, it is composite modified with SBS to prepare high-performance modified asphalt and further prepare a mixture capable of ultra-thin overlays.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A hyperbranched amine rubber for ultra-thin overlays, wherein the monomers of the hyperbranched amine rubber comprise a structure as shown in formula (I).

[0007]

[0008] (I) R1 represents any one of alkyl, benzene ring group or monohydric alcohol; R2 represents any one of hydrogen atom, amide group, alkyl or alkylamide.

[0009] Furthermore, the hyperbranched amine rubber is prepared by polymerization reaction of raw materials comprising the following parts by weight: 100 parts of unsaturated amine, 30-70 parts of butadiene, 10-50 parts of ethylene derivative, and 0.5-1 parts of catalyst.

[0010] Furthermore, the unsaturated amine is any one of acrylamide, stearamide, N-vinylacetamide, ethynylbenzamide, and N,N-methylenebisacrylamide; the ethylene derivative is any one of styrene, p-methylstyrene, methyl allyl alcohol, 9-octadecene, 2-butene, cyclohexene, and 3-methylcyclohexene; and the catalyst is any one of imidazolinide, (bpy)CuI / TEMPO, nitrogen-containing heterocyclic carbene, Brønsted acid, and RuCl2(PPh3)3.

[0011] The present invention also provides a modified asphalt for ultra-thin overlays, the modified asphalt comprising the following raw materials in parts by weight: 100 parts of base asphalt, 5-15 parts of SBS modifier, 0.1-0.4 parts of stabilizer, 2-10 parts of hyperbranched amine rubber, and 0-8 parts of rubber oil.

[0012] Furthermore, the base asphalt is 70# base asphalt; the stabilizer is sulfur.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The hyperbranched amine rubber synthesized in this invention possesses a highly branched three-dimensional molecular structure containing a large number of active amine groups. This allows for strong physicochemical interactions with asphalt components, significantly improving the adhesion, cohesive strength, and elastic recovery of the asphalt. Ethylene derivatives are used to improve the high-temperature performance and PG grade of the modified asphalt, while butadiene provides low-temperature crack resistance and a lower low-temperature grade. Unsaturated amines primarily enhance the adhesion between aggregates and asphalt, improving the water damage resistance of PG100-34 modified asphalt mixtures.

[0015] 2. Composite modification of hyperbranched amine rubber with SBS produced a significant synergistic effect. Hyperbranched amine rubber not only enhances the properties of asphalt itself, but also promotes the dispersion and cross-linking network formation of SBS in asphalt. Furthermore, it may improve compatibility through the reaction of amine groups with acidic components in asphalt, thereby producing high-performance modified asphalt with a performance grade of PG100-34 (i.e., high-temperature performance meets 100℃ and low-temperature performance meets -34℃).

[0016] 3. The ultra-thin overlay mixture based on this PG100-34 modified asphalt has excellent comprehensive performance. It can effectively balance high-temperature rutting resistance, low-temperature crack resistance and fatigue cracking resistance. It solves the technical problems of scattering, peeling and poor durability that are common in traditional ultra-thin overlays, greatly extends the service life of the road surface and improves driving safety and comfort. Attached Figure Description

[0017] Figure 1 This is the chemical equation for the synthesis of hyperbranched amine rubber in the embodiments of the present invention;

[0018] Figure 2 This is the infrared spectrum of the hyperbranched amine rubber prepared in Example 1 of this invention. Detailed Implementation

[0019] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0020] This invention provides a hyperbranched amine rubber for an ultrathin overlay, wherein the monomer of the hyperbranched amine rubber comprises a structure as shown in formula (I).

[0021]

[0022] (I), where R1 represents any one of alkyl, benzene ring group or monohydric alcohol; R2 represents any one of amide group, alkyl or alkylamide.

[0023] Hyperbranched amine rubber is prepared by polymerization of the following raw materials in parts by weight: 100 parts unsaturated amine, 30-70 parts butadiene, 10-50 parts ethylene derivative, and 0.5-1 parts catalyst. The unsaturated amine is any one of acrylamide, stearamide, ethyleneamine, acetyleneamine, oleylamine, 3-buten-1-amine, and N,N-methylenebisacrylamine. The group represented by R2 is derived from the unsaturated amide, specifically any one of hydrogen atom, amide group, alkyl group, and alkylamide.

[0024] The ethylene derivative is any one of styrene, p-methylstyrene, methylallyl alcohol, 9-octadecene, 2-butene, cyclohexene, and 3-methylcyclohexane. R1 represents a group derived from ethylene derivatives, such as any one of alkyl, benzene ring, or monohydric alcohol groups. The catalyst is any one of imidazolinide, (bpy)CuI / TEMPO, nitrogen-containing heterocyclic carbene, Brønsted acid, and RuCl2(PPh3)3.

[0025] The polymerization reaction steps are as follows: unsaturated amine, butadiene, ethylene derivative, and catalyst are placed into a reaction apparatus according to their weight proportions. After purging with a protective gas, the temperature is raised to 25-100℃, and the reaction is stirred for 15-30 hours to obtain hyperbranched amine rubber. The reaction apparatus includes equipment such as a reaction vessel that can be used for polymerization reactions, and the protective gas is an inert gas such as nitrogen.

[0026] This invention also provides a modified asphalt for ultra-thin overlays prepared using the aforementioned hyperbranched amine rubber. The modified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 5-15 parts SBS modifier, 0.1-0.4 parts stabilizer, 2-10 parts hyperbranched amine rubber, and 0-8 parts rubber oil. The base asphalt is 70# base asphalt, selected from any one of Korean S-oil asphalt, GS asphalt, SK asphalt, Hainan Jingbo asphalt, and Zhenhai asphalt. The SBS modifier is any one of Sibur L30-01A, R30-00A, L330, and R330. The stabilizer is sulfur.

[0027] The preparation method of modified asphalt is as follows: weigh the base asphalt, SBS modifier, stabilizer, hyperbranched amine rubber and rubber oil according to the weight parts, and mix them at high speed at 170~200℃ for 30~150min, and then stir and develop at 180~200℃ for 3~6h to obtain the modified asphalt.

[0028] This invention also provides an asphalt mixture for ultra-thin overlay prepared using the above-mentioned modified asphalt. The asphalt mixture further includes aggregates and mineral powder, wherein the modified asphalt serves as a binder. The aggregates and mineral powder can be designed according to the YH-PAVE10 gradation, and the amount of modified asphalt added is 7.5-8% of the aggregate mass. The asphalt mixture is designed and mixed according to conventional hot-mix asphalt mixture design methods (such as the Marshall process or the Superpave process).

[0029] Example 1

[0030] This embodiment provides a hyperbranched amine rubber for ultra-thin overlays, which is prepared by polymerization reaction from raw materials comprising the following parts by weight: 100 parts by weight of acrylamide, 30 parts by weight of butadiene, 10 parts by weight of styrene and 0.5 parts by weight of imidazolinone catalyst.

[0031] This embodiment also provides a method for preparing hyperbranched amine rubber for ultrathin overlays, as shown in the attached figure. Figure 1The process includes the following steps: In a nitrogen-protected reactor, 100 parts by weight of acrylamide, 30 parts by weight of butadiene, 10 parts by weight of styrene, and 0.5 parts by weight of imidazolinone catalyst are added. The reaction system temperature is raised to 25°C, and the reaction is stirred at this temperature for 30 hours. After the reaction is completed, a pale yellow viscous solid is obtained after post-treatment, which is the hyperbranched amine rubber, and its monomer is shown in Formula II below, with a yield of 85%.

[0032]

[0033] (II).

[0034] This embodiment also provides a modified asphalt for ultra-thin overlays, comprising the following raw materials in parts by weight: 100 parts of 70# base asphalt, 5 parts of SBS modifier, 0.1 parts of stabilizer, and 2 parts of hyperbranched amine rubber.

[0035] This embodiment also provides a method for preparing modified asphalt for ultra-thin overlays, comprising the following steps: Weighing 100 parts by weight of SK 70# base asphalt and heating it to 180°C to melt and flow. While stirring, sequentially adding 5 parts by weight of SBS modifier (Sibur L330), 0.1 parts by weight of sulfur stabilizer, and 2 parts by weight of the hyperbranched amine rubber prepared above. Maintaining the temperature at 180°C, shearing is performed using a high-speed shearing machine at 5000 rpm for 30 minutes. After shearing, the mixture is transferred to a development tank and slowly stirred and developed at 180°C for 3 hours to obtain the modified asphalt.

[0036] This embodiment also provides an asphalt mixture for ultra-thin overlays, comprising the modified asphalt and aggregates prepared above, wherein the modified asphalt content is 7.5% of the aggregate mass, and the aggregates are formulated according to YH-PAVE10 gradation, comprising 68% coarse aggregates (53% with particle sizes of 4.75mm~9.5mm, 15% with particle sizes of 2.36~4.75mm), 27% fine aggregates (0~2.36mm), and 5% mineral powder (0~0.6mm). It is prepared by the following method: the modified asphalt and aggregates prepared above are weighed according to the proportion, and the aggregates heated to 190-200℃ and the modified asphalt heated to 180℃ are mixed evenly in a mixing mill to prepare the ultra-thin overlay asphalt mixture.

[0037] Example 2

[0038] This embodiment provides a hyperbranched amine rubber for ultra-thin overlays, which is prepared by polymerization reaction from raw materials comprising the following parts by weight: 100 parts by weight of N-vinylacetamide, 70 parts by weight of butadiene, 50 parts by weight of p-methylstyrene and 1 part by weight of nitrogen heterocyclic carbene catalyst.

[0039] This embodiment also provides a method for preparing hyperbranched amine rubber for ultra-thin overlays, comprising the following steps: in a nitrogen-protected reactor, 100 parts by weight of N-vinylacetamide, 70 parts by weight of butadiene, 50 parts by weight of p-methylstyrene, and 1 part by weight of a nitrogen-containing heterocyclic carbene catalyst are added. The temperature of the reaction system is raised to 100°C, and the reaction is stirred at this temperature for 15 hours. After the reaction is completed, a pale yellow viscous solid is obtained after post-treatment, which is the hyperbranched amine rubber, with a yield of 90%. This embodiment also provides a modified asphalt for ultra-thin overlays, comprising the following raw materials in parts by weight: 100 parts of 70# base asphalt, 15 parts of SBS modifier, 0.4 parts of stabilizer, 10 parts of hyperbranched amine rubber, and 8 parts by weight of rubber oil.

[0040] This embodiment also provides a method for preparing modified asphalt for ultra-thin overlays, comprising the following steps: Weigh 100 parts by weight of SK 70# base asphalt and heat it to 180°C to melt and flow. While stirring, add 15 parts by weight of SBS modifier (R30-00A), 0.4 parts by weight of sulfur stabilizer, 10 parts by weight of hyperbranched amine rubber, and 8 parts by weight of rubber oil in sequence. Maintain the temperature at 180°C and shear at 5000 rpm for 15 minutes using a high-speed shearing machine. After shearing, transfer to a development tank and slowly stir and develop at 180°C for 3 hours to obtain the modified asphalt.

[0041] This embodiment also provides an asphalt mixture for ultra-thin overlays, comprising the modified asphalt and aggregates prepared above, wherein the modified asphalt content is 7.8% of the aggregate mass, and the aggregates are formulated according to YH-PAVE10 gradation, including 68% coarse aggregates (53% 4.75mm~9.5mm, 15% 2.36~4.75mm), 27% fine aggregates (0~2.36mm), and 5% mineral powder (0~0.6mm). It is prepared by the following method: the modified asphalt and aggregates prepared above are weighed according to the proportion, and the aggregates heated to 190-200℃ and the modified asphalt heated to 180℃ are mixed evenly in a mixing mill to prepare the ultra-thin overlay asphalt mixture.

[0042] Example 3

[0043] This embodiment provides a hyperbranched amine rubber for ultra-thin overlays, which is prepared by polymerization reaction from raw materials comprising the following parts by weight: 100 parts by weight of N,N-methylenebisacrylamide, 50 parts by weight of butadiene, 30 parts by weight of 9-octadecene and 0.8 parts by weight of Brønsted acid catalyst.

[0044] This embodiment also provides a method for preparing hyperbranched amine rubber for ultra-thin coatings, comprising the following steps: In a nitrogen-protected reactor, 100 parts by weight of N,N-methylenebisacrylamide, 50 parts by weight of butadiene, 30 parts by weight of 9-octadecene, and 0.8 parts by weight of Brønsted acid catalyst are added. The reaction system temperature is raised to 60°C, and the reaction is stirred at this temperature for 25 hours. After the reaction is completed, a pale yellow viscous solid is obtained after post-treatment, which is the hyperbranched amine rubber, with a yield of 92%.

[0045] This embodiment also provides a modified asphalt for ultra-thin overlays, comprising the following raw materials in parts by weight: 100 parts of 70# base asphalt, 10 parts of SBS modifier, 0.3 parts of stabilizer, 7 parts of hyperbranched amine rubber, and 5 parts by weight of rubber oil.

[0046] This embodiment also provides a method for preparing modified asphalt for ultra-thin overlays, comprising the following steps: Weigh 100 parts by weight of SK 70# base asphalt and heat it to 180°C to melt and flow. While stirring, add 10 parts by weight of SBS modifier (R330), 0.3 parts by weight of sulfur stabilizer, 7 parts by weight of hyperbranched amine rubber, and 5 parts by weight of rubber oil in sequence. Maintain the temperature at 180°C and shear at 5000 rpm for 90 minutes using a high-speed shearing machine. After shearing, transfer to a development tank and slowly stir and develop at 180°C for 5 hours to obtain the modified asphalt.

[0047] This embodiment also provides an asphalt mixture for ultra-thin overlays, comprising the modified asphalt and aggregates prepared above, wherein the modified asphalt content is 7.5% of the aggregate mass, and the aggregates are formulated according to YH-PAVE10 gradation, including 68% coarse aggregates (53% 4.75mm~9.5mm, 15% 2.36~4.75mm), 27% fine aggregates (0~2.36mm), and 5% mineral powder (0~0.6mm). It is prepared by the following method: the modified asphalt and aggregates prepared above are weighed according to the proportion, and the aggregates heated to 190-200℃ and the modified asphalt heated to 180℃ are mixed evenly in a mixing mill to prepare the ultra-thin overlay asphalt mixture.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 3 is that hyperbranched amine rubber was not used in the preparation of the modified asphalt, and neither hyperbranched amine rubber nor its preparation method was provided. The other steps are the same as in Example 3.

[0050] Comparative Example 2

[0051] Compared to Example 1, this comparative example did not include butadiene in the preparation of the hyperbranched amine rubber. Instead, the following steps were used: 100 parts by weight of acrylamide, 10 parts by weight of styrene, and 0.5 parts by weight of imidazolinone catalyst were added to a nitrogen-protected reactor. The reaction system temperature was raised to 25°C, and the reaction was stirred at this temperature for 30 hours. After the reaction, a transparent viscous liquid was obtained through post-treatment. This substance was used in modified asphalt and modified asphalt mixtures. The preparation process of the modified asphalt and modified asphalt mixtures was the same as in Example 1.

[0052] Comparison 3

[0053] Compared to Example 1, this comparative example uses an excess of 90 parts by weight of butadiene in the preparation of hyperbranched amine rubber. The steps include: adding 100 parts by weight of acrylamide, 90 parts by weight of butadiene, 10 parts by weight of styrene, and 0.5 parts by weight of imidazolinone catalyst to a nitrogen-protected reactor. The reaction system temperature is raised to 25°C, and the reaction is stirred at this temperature for 30 hours. After the reaction, a pale yellow viscous liquid is obtained after post-treatment. This substance is used in modified asphalt and modified asphalt mixtures. The preparation process of the modified asphalt and modified asphalt mixtures is the same as in Example 1.

[0054] Performance tests were conducted on the modified asphalt and modified asphalt mixtures prepared in the examples and comparative examples in accordance with the relevant test specifications of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025); the test results are shown in Tables 1 and 2 below.

[0055] Table 1 Technical indicators of modified asphalt prepared in Example 1 and the comparative example

[0056]

[0057] Table 2 Technical specifications of ultrathin asphalt mixtures prepared in the examples and comparative examples.

[0058]

[0059] Table 1 shows that the softening point, composite shear modulus G* at 60℃, and Brookfield rotational viscosity at 60℃ of the hyperbranched amine rubber modified asphalt prepared in Examples 1-3 are all higher than those of the modified asphalt without hyperbranched amine rubber in Comparative Example 1, and the modified asphalts with butadiene content exceeding the specified range in Comparative Examples 2 and 3. Furthermore, the PG grade of the modified asphalt in Examples 1-3 can all reach PG100-34, while the PG of the asphalt without hyperbranched amine rubber in Comparative Example 1 is only 82-22, and the PG of the synthesized hyperbranched amine rubber in Comparative Example 2 is significantly lower. The PG grade of asphalt without butadiene modification was PG76-22. In Comparative Example 3, the PG grade of asphalt modified with excessive butadiene content during the synthesis of hyperbranched amine rubber was PG88-28, significantly lower than PG100-34. This indicates that the addition of hyperbranched amine rubber can result in a highly branched three-dimensional molecular structure containing a large number of active amine groups, which can generate strong physicochemical interactions with asphalt components, significantly improving the asphalt's adhesion and cohesive strength. Through the reaction of amine groups with acidic components in the asphalt, the softening point and PG grade of the asphalt are increased. Furthermore, Comparative Examples 2 and 3 show that the amount of butadiene used in the synthesis of hyperbranched amine rubber should be strictly controlled. This is because butadiene provides long-chain flexible groups in the hyperbranched amine rubber molecular chain, giving the rubber its elasticity and strength. As can be seen from the performance of the modified asphalt mixtures prepared in Table 2, the performance of the ultrathin asphalt mixtures prepared in Examples 1-3 all meet the technical requirements, while the dynamic stability at 60℃ and the four-point bending fatigue (15℃, 1000με) of Comparative Examples 1-3 do not meet the requirements. This is because hyperbranched amine rubber modified asphalt was used in Examples 1-3, with a PG grade of PG100-34. The modified asphalt prepared in these examples has excellent high and low temperature performance, and the high asphalt-aggregate ratio design (asphalt-aggregate ratio > 7.5%) improves the fatigue crack resistance of the asphalt mixture. Therefore, the four-point bending fatigue life at 15℃ and 1000με is much higher than the technical requirement of >500,000 cycles.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A hyperbranched amine rubber for ultra-thin overlays, characterized in that: The monomer of the hyperbranched amine rubber has the structure shown in formula (Ⅰ). (I) R1 represents any one of alkyl, benzene ring group or monohydric alcohol; R2 represents any one of hydrogen atom, amide group, alkyl or alkylamide.

2. The hyperbranched amine rubber for ultra-thin overlays according to claim 1, characterized in that: The hyperbranched amine rubber is prepared by polymerization reaction of raw materials comprising the following parts by weight: 100 parts unsaturated amine, 30-70 parts butadiene, 10-50 parts ethylene derivative, and 0.5-1 parts catalyst.

3. The hyperbranched amine rubber for ultra-thin overlays according to claim 2, characterized in that: The unsaturated amine is any one of acrylamide, stearamide, ethyleneamine, acetyleneamine, and N,N-methylenebisacrylamide; the ethylene derivative is any one of styrene, p-methylstyrene, methylallyl alcohol, 9-octadecene, 2-butene, cyclohexene, and 3-methylcyclohexene; the catalyst is any one of imidazolinide, (bpy)CuI / TEMPO, nitrogen-containing heterocyclic carbene, Brønsted acid, and RuCl2(PPh3)3.

4. A modified asphalt for ultrathin overlays prepared from the hyperbranched amine rubber according to any one of claims 1-3.

5. The modified bitumen for ultra-thin overlays according to claim 4, characterized in that: The modified asphalt comprises the following raw materials in parts by weight: 100 parts base asphalt, 5-15 parts SBS modifier, 0.1-0.4 parts stabilizer, 2-10 parts hyperbranched amine rubber, and 0-8 parts rubber oil.

6. The modified bitumen for ultra-thin overlays according to claim 5, characterized in that: The base asphalt is 70# base asphalt; the stabilizer is sulfur; and the SBS modifier is styrene-butadiene-styrene triblock copolymer or styrene-based thermoplastic elastomer.

7. An asphalt mixture for ultra-thin overlay prepared from the modified asphalt according to any one of claims 4-6.

8. The asphalt mixture for ultra-thin overlays according to claim 7, characterized in that: The asphalt mixture also includes aggregates and mineral powder, and the amount of modified asphalt used in the asphalt mixture is 7.5 to 8% of the mass of the aggregates.

9. The method for preparing the hyperbranched amine rubber for ultra-thin overlays according to any one of claims 1-3, characterized in that: The process includes the following steps: placing unsaturated amines, butadiene, ethylene derivatives and catalysts into a reaction apparatus according to their weight proportions, purging with protective gas and heating to 25-100°C for reaction, stirring the reaction for 15-30 hours to obtain hyperbranched amine rubber.

10. The method for preparing modified asphalt for ultra-thin overlays according to any one of claims 4-6, characterized in that: The process includes the following steps: weighing the base asphalt, SBS modifier, stabilizer, hyperbranched amine rubber, and rubber oil according to their weight proportions, and then mixing them at high speed at 170-200℃ for 30-150 min, followed by stirring and developing at 180-200℃ for 3-6 h to obtain the modified asphalt.

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