Drainage asphalt mixture and method for producing the same

Abstract

The application discloses a drainage asphalt mixture and a preparation method thereof, and belongs to the field of road materials. The product is prepared by introducing specific modified bamboo charcoal powder and plant fiber into components, and under the action of a specific compatible system, the product has high porosity after being spread on the road surface, and can achieve sufficient drainage effect when meeting water. In addition, the product has good high-temperature stability, and can avoid the rolling deformation of vehicles in high-temperature environments such as summer. In the drainage process, the product has excellent anti-loosening and peeling performance, and can avoid the problems of gravel peeling and pit and groove caused by internal water pressure.

Description

Technical Field

[0001] This invention relates to the field of road materials, specifically to a drainage asphalt mixture and its preparation method. Background Technology

[0002] Drainage asphalt pavements mainly use two methods for drainage: surface runoff and internal seepage within the structural layer. Especially during the rainy season when water retention is prolonged, a large area of ​​flowing water will be generated on the road surface. If continuous internal seepage is not carried out at the same time, the water will not be able to leave the road surface in time, which will pose a great safety hazard to passing vehicles.

[0003] Therefore, the mixtures used in drainage asphalt pavements often contain a relatively rich porous structure to ensure that water can be quickly guided into the ground when it infiltrates. However, this structure also brings many defects: poor stability, high degree of particle separation, easy formation of particle accumulation inside, and easy blockage of pores in the later stage, resulting in poor drainage. Summary of the Invention

[0004] Based on the deficiencies of existing technologies, the present invention aims to provide a drainage asphalt mixture. By introducing specific modified bamboo charcoal powder and plant fiber into the components, under the action of a specific compatible system, the special interaction between the two results in a product with high porosity after being paved into a road surface, which can achieve a sufficient drainage effect when exposed to water. In addition, the product has good high-temperature stability, avoiding deformation caused by vehicle rolling in high-temperature environments such as summer. During the drainage process, the product has excellent anti-loosening and spalling properties, which can avoid the problem of gravel falling off and potholes caused by internal dynamic water pressure.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A drainage asphalt mixture comprises the following components in parts by weight: 5-15 parts asphalt, 1-3 parts styrene-butadiene-styrene front copolymer (SBS), 5-10 parts plant fiber, 5-10 parts hyperbranched polyester modified bamboo charcoal powder, 180-190 parts graded aggregate, 1-10 parts petroleum resin, and 1-5 parts compatibilizer; wherein the compatibilizer is maleic anhydride grafted polyethylene wax.

[0007] Generally speaking, the key drainage pore structure in drainage asphalt mixtures is mainly achieved by the combination of aggregates of different sizes. Therefore, in order to achieve a larger porosity, people try to optimize and screen the graded aggregates. However, after optimizing the formula and achieving a larger porosity, the particle stability, high and low temperature stability, and strength properties of the product will decrease, which will reduce the durability and practicality of the product. At the same time, after using some specially graded aggregates, due to their larger specific surface area, their compatibility with asphalt and other components will also decrease, further weakening the various properties of the product. Therefore, in this invention, the inventors optimize the porosity of the product by using a compound system of three key components: plant fiber, hyperbranched polyester-modified bamboo charcoal powder, and maleic anhydride-grafted polyethylene wax. This improves the product's drainage performance while ensuring sufficient structural stability, strength, and high-temperature stability. Plant fiber has excellent adsorption and binding strength, but it contains a large number of surface hydroxyl groups and has a certain degree of water absorption and swelling. Therefore, although there are existing technologies that use it in asphalt mixtures to improve product strength and particle bonding, the compatibility of plant fiber with asphalt, aggregates, and other components in such products is not ideal, and it also has poor water resistance and is very easy to absorb water. Water swelling, and long-term water absorption / dehydration-swelling / shrinkage, can cause particles to loosen and fall off. To address this, the inventors introduced hyperbranched polyester-modified bamboo charcoal powder as an auxiliary agent. Bamboo charcoal is a biomass formed by the carbonization of bamboo, which retains the biomass structure of bamboo itself. It has high microscopic particle strength and good structural stability. After being modified with hyperbranched polyester, it has high adsorption capacity. Therefore, when mixed with plant fibers, it will directly adsorb onto the surface of the plant fibers to form a protective shell, inhibiting the water absorption and swelling of the plant fibers. The grafted hyperbranched polyester itself has abundant compatibility groups, which can effectively improve the compatibility of the coated plant fibers, further enhancing the strength and stability of the product. On the other hand, polyethylene wax, which has waterproofing properties, is a common additive in drainage asphalt mixtures. However, because polyethylene wax is difficult to combine well with aggregates, fibers, and even SBS resin in the product, it slowly precipitates out after a period of product preparation, failing to provide adequate waterproofing. To address this, the inventors replaced pure polyethylene wax with maleic anhydride-grafted polyethylene wax. This not only effectively improves the compatibility of each component with the polyethylene wax but also acts as a compatibilizer to enhance the compatibility between inorganic and organic components in the product. Furthermore, this compatibilizer can also act as a toughening agent, synergistically enhancing the strength of the product with SBS and plant fibers, resulting in a significant improvement in the product's anti-scattering properties, strength, and stability.

[0008] Preferably, the asphalt is at least one of 70# asphalt and 90# asphalt.

[0009] Preferably, the plant fiber is at least one of wood fiber, bamboo fiber, and plant shell fiber.

[0010] Preferably, the plant fiber is bamboo fiber.

[0011] More preferably, the method for preparing the bamboo fiber includes the following steps:

[0012] (1) Cut the dried bamboo stems into thin slices, wash and dry them to obtain coarse bamboo slices;

[0013] (2) The coarse bamboo pieces are crushed and processed, and the resulting powder is passed through a 200-400 mesh sieve to obtain fine bamboo powder;

[0014] (3) Disperse fine bamboo powder in ethanol, sonicate for 10-15 min, and dry to obtain the bamboo fiber.

[0015] It should be noted that the bamboo fiber described in this invention is not limited to the above-described preparation method. Those skilled in the art can also use commercially available products or products prepared by other methods to prepare the drainage asphalt mixture described in this invention according to actual needs, as long as similar or identical technical effects are obtained.

[0016] Bamboo is rich in cellulose, hemicellulose, and lignin, and its microscopic biomass structure is tightly arranged, giving it higher strength and stability compared to other plant fibers. Using bamboo fiber in combination with the modified bamboo charcoal powder described in this invention not only improves the compatibility of the two but also unifies their sources. By using abundant bamboo as raw material, the high-strength bamboo nodes are prepared into bamboo fiber, while the remaining portion is prepared into modified bamboo charcoal powder, resulting in higher economic benefits.

[0017] Preferably, the preparation method of the hyperbranched polyester-modified bamboo charcoal powder includes the following steps:

[0018] (1) Wash, dry, and pass bamboo charcoal powder through a 100-200 mesh sieve before dispersing it in an organic solvent to obtain a bamboo charcoal dispersion.

[0019] (2) Add silane coupling agent to bamboo charcoal dispersion and heat to 60~70℃ and stir for 2~3h to evaporate organic solvent completely to obtain silane modified bamboo charcoal powder;

[0020] (3) Mix silane-modified bamboo charcoal powder, hyperbranched polyester and initiator and put them into a screw extruder for melt extrusion at 150~200℃ to obtain the hyperbranched polyester-modified bamboo charcoal powder.

[0021] Preferably, the hyperbranched polyester is a hydroxyl-terminated hyperbranched polyester.

[0022] More preferably, the hyperbranched polyester is a HyPer series product produced by Wuhan Hyperbranched Polyester Co., Ltd., and is at least one of H10, H20, H30 and H40 products.

[0023] More preferably, the mass ratio of the silane-modified bamboo charcoal powder to the hyperbranched polyester is 1:(0.1~0.3).

[0024] Hyperbranched polyester is a dendritic polymer that exhibits excellent bonding and compatibility properties when compounded with inorganic phases. Furthermore, compared to other types such as end-carboxyl hyperbranched polyester, the inventors' experiments have shown that bamboo charcoal powder modified with end-hydroxyl hyperbranched polyester has the greatest improvement in the component compatibility and stability of the product. It also results in higher bonding strength and less particle loss in the product. While other types of hyperbranched polyester may produce products with higher strength and other properties, they do not adequately improve the compatibility of the overall material, especially between organic and inorganic components, and may still result in some particle loss.

[0025] Preferably, the grafting rate of maleic anhydride in the maleic anhydride-grafted polyethylene wax is 5-8%.

[0026] More preferably, the maleic anhydride-grafted polyethylene wax is Licocene PE MA 4351, manufactured by Clariant.

[0027] In addition, those skilled in the art can also prepare it using a self-made method, the specific steps of which are: melting polyethylene wax, then transferring it to a screw extruder and adding maleic anhydride and an initiator to mix and extrude, thereby obtaining the maleic anhydride-grafted polyethylene wax.

[0028] Preferably, the graded aggregate includes coarse aggregate and fine aggregate;

[0029] More preferably, the mass ratio of the coarse aggregate to the fine aggregate is (9:1) to (8:2).

[0030] More preferably, the coarse aggregate gradation is as follows: the mass percentage of aggregate passing through a 13.8mm sieve but not through a 12.8mm sieve is 1-10%; the mass percentage of aggregate passing through a 12.8mm sieve but not through an 8.8mm sieve is 30-45%; the mass percentage of aggregate passing through an 8.8mm sieve but not through a 5.4mm sieve is 30-45%; the mass percentage of aggregate passing through a 5.4mm sieve but not through a 3.3mm sieve is 1-5%; the mass percentage of aggregate passing through a 3.3mm sieve but not through a 1.12mm sieve is 1-5%; and the remaining mass percentage of aggregate passing through a 1.12mm sieve is aggregate.

[0031] More preferably, the gradation of the fine aggregate is as follows: 100% of the aggregate passes through a 1.12mm sieve; 20-40% of the aggregate passes through a 1.12mm sieve but not through a 0.63mm sieve; 20-40% of the aggregate passes through a 0.63mm sieve but not through a 0.21mm sieve; 20-40% of the aggregate passes through a 0.21mm sieve but not through a 0.08mm sieve; and the remaining aggregate passes through a 0.08mm sieve.

[0032] Another object of the present invention is to provide a method for preparing the drainage asphalt mixture, comprising the following steps:

[0033] (1) Mix asphalt, SBS, hyperbranched polyester modified bamboo charcoal powder, petroleum resin and compatibilizer evenly to obtain a mixture;

[0034] (2) Mix the mixture with plant fiber and graded aggregate evenly to obtain the drainage asphalt mixture.

[0035] The preparation process of the drainage asphalt mixture described in this invention is simple and does not require special equipment, enabling large-scale production.

[0036] Preferably, in step (1), the temperature of the mixture during preparation is 180~200℃ and the mixing rate is 150~250rpm.

[0037] Preferably, in step (2), the temperature of the drainage asphalt mixture during mixing is 150~180℃ and the mixing rate is 150~250rpm.

[0038] The beneficial effects of this invention are as follows: This invention provides a drainage asphalt mixture, which, by introducing specific modified bamboo charcoal powder and plant fiber into the components, achieves a high porosity after being paved into a road surface through the special interaction of the two under the action of a specific compatible system, thus achieving a sufficient drainage effect when exposed to water; in addition, the product has good high-temperature stability, avoiding deformation caused by vehicle rolling in high-temperature environments such as summer; during the drainage process, the product has excellent anti-loosening and spalling performance, which can avoid the problem of gravel falling off and potholes caused by internal dynamic water pressure. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0040] Example 1

[0041] An embodiment of the drainage asphalt mixture and its preparation method according to the present invention comprises the following components in parts by weight: 10 parts asphalt, 2 parts SBS, 8 parts plant fiber, 8 parts hyperbranched polyester modified bamboo charcoal powder, 185 parts graded aggregate, 5 parts petroleum resin, and 2 parts compatibilizer.

[0042] The asphalt in question is commercially available 70# asphalt;

[0043] The SBS mentioned is the 411S manufactured by LG in South Korea.

[0044] The plant fiber is bamboo fiber, which is a self-made product. The preparation method includes the following steps:

[0045] (1) Take the dried bamboo stems from a bamboo forest in Huadu and cut them into thin slices beforehand. After washing and drying, coarse bamboo slices are obtained.

[0046] (2) The coarse bamboo strips are crushed by a crusher, and the resulting powder is passed through a 300-mesh sieve to obtain fine bamboo powder;

[0047] (3) Disperse fine bamboo powder in ethanol, sonicate at 100W for 15 minutes, and dry to obtain the bamboo fiber powder.

[0048] The hyperbranched polyester-modified bamboo charcoal powder is a self-made product, and its preparation method is as follows:

[0049] (1) The bamboo charcoal powder was washed, dried and passed through a 200-mesh sieve before being dispersed in ethanol (solid-liquid ratio 1 g / mL) to obtain a bamboo charcoal dispersion.

[0050] (2) Add silane coupling agent KH550 (5wt% of bamboo charcoal powder) to the bamboo charcoal dispersion and heat to 65℃ and stir for 3h. Volatilize the ethanol completely to obtain silane-modified bamboo charcoal powder.

[0051] (3) Mix silane-modified bamboo charcoal powder, hyperbranched polyester HyPer H20 produced by Wuhan Hyperbranching (mixed at a mass ratio of 1:0.2) and an appropriate amount of initiator DCP and place them in a twin-screw extruder for melt extrusion at 180~190℃ to obtain the hyperbranched polyester-modified bamboo charcoal powder. The screw length-to-diameter ratio is 48:1.

[0052] The bamboo charcoal powder is carbon powder obtained by burning the remaining bamboo nodes of moso bamboo used in the preparation of bamboo fiber.

[0053] The graded aggregate consists of coarse aggregate and fine aggregate.

[0054] More preferably, the mass ratio of the coarse aggregate to the fine aggregate is 8.5:1.5.

[0055] The coarse aggregate gradation is as follows: 8% of the aggregate passes through a 13.8mm sieve but not through a 12.8mm sieve; 40% of the aggregate passes through a 12.8mm sieve but not through an 8.8mm sieve; 40% of the aggregate passes through an 8.8mm sieve but not through a 5.4mm sieve; 3% of the aggregate passes through a 5.4mm sieve but not through a 3.3mm sieve; 4% of the aggregate passes through a 3.3mm sieve but not through a 1.12mm sieve; and the remaining 5% of the aggregate passes through a 1.12mm sieve.

[0056] The fine aggregate gradation is as follows: 35% of the aggregate passes through a 1.12mm sieve but not through a 0.63mm sieve; 35% of the aggregate passes through a 0.63mm sieve but not through a 0.21mm sieve; 25% of the aggregate passes through a 0.21mm sieve but not through a 0.08mm sieve; and the remaining 5% of the aggregate passes through a 0.08mm sieve.

[0057] The petroleum resin is C9 petroleum resin;

[0058] The compatibilizer is maleic anhydride-grafted polyethylene wax, specifically Licocene PE MA 4351 manufactured by Clariant, with a grafting rate of 7%~8%.

[0059] The method for preparing the drainage asphalt mixture includes the following steps:

[0060] (1) Mix asphalt, styrene-butadiene-styrene front copolymer (SBS), hyperbranched polyester modified bamboo charcoal powder, petroleum resin and compatibilizer, heat to 190°C and stir evenly at a speed of 200 rpm to obtain a mixture.

[0061] (2) Mix the mixture with plant fiber and graded aggregate, heat to 170°C and stir evenly at a speed of 200 rpm to obtain the drainage asphalt mixture.

[0062] Example 2

[0063] An embodiment of the drainage asphalt mixture and its preparation method of the present invention differs from Embodiment 1 only in that the drainage asphalt mixture comprises the following components in parts by weight: 8 parts asphalt, 3 parts SBS, 7 parts plant fiber, 10 parts hyperbranched polyester modified bamboo charcoal powder, 180 parts graded aggregate, 8 parts petroleum resin, and 4 parts compatibilizer.

[0064] Example 3

[0065] An embodiment of the drainage asphalt mixture and its preparation method of the present invention differs from Embodiment 1 only in that the drainage asphalt mixture comprises the following components in parts by weight: 12 parts asphalt, 1 part SBS, 9 parts plant fiber, 5 parts hyperbranched polyester modified bamboo charcoal powder, 185 parts graded aggregate, 5 parts petroleum resin, and 3 parts compatibilizer.

[0066] Example 4

[0067] An embodiment of the drainage asphalt mixture and its preparation method according to the present invention differs from Embodiment 1 only in that the bamboo fiber is replaced with oak fiber, which is a self-made product. The preparation method includes the following steps:

[0068] (1) The dried oak tree trunks produced in a certain place in Hainan were first cut into thin slices, washed and dried to obtain coarse tree trunk slices;

[0069] (2) The coarse tree trunk pieces are crushed by a crusher, and the resulting powder is passed through a 300-mesh sieve to obtain fine oak powder;

[0070] (3) Disperse fine oak powder in ethanol, sonicate at 100W for 15 minutes, and dry to obtain the oak fiber powder.

[0071] Example 5

[0072] An embodiment of the drainage asphalt mixture and its preparation method according to the present invention differs from Embodiment 1 only in that the bamboo fiber is replaced with rice husk fiber, which is a self-made product. The preparation method includes the following steps:

[0073] (1) Wash and dry the dried rice husk waste produced in a certain place in Conghua;

[0074] (2) The rice husk waste is crushed by a crusher and the resulting powder is passed through a 300-mesh sieve to obtain rice husk powder;

[0075] (3) Disperse the rice husk powder in ethanol, sonicate it at 100W for 15 minutes, and dry it to obtain the rice husk fiber powder.

[0076] Example 6

[0077] An embodiment of the drainage asphalt mixture and its preparation method described in this invention differs from Embodiment 1 only in that the hyperbranched polyester used in the hyperbranched polyester modified bamboo charcoal powder is HyPer H30 produced by Wuhan Hyperbranched Chemical Co., Ltd.

[0078] Example 7

[0079] An embodiment of the drainage asphalt mixture and its preparation method described in this invention differs from Embodiment 1 only in that the hyperbranched polyester used in the hyperbranched polyester modified bamboo charcoal powder is HyPer C20 produced by Wuhan Hyperbranched Chemical Co., Ltd.

[0080] Example 8

[0081] An embodiment of the drainage asphalt mixture and its preparation method described in this invention differs from Embodiment 1 only in that the hyperbranched polyester used in the hyperbranched polyester modified bamboo charcoal powder is HyPer C100 produced by Wuhan Hyperbranched Chemical Co., Ltd.

[0082] Comparative Example 1

[0083] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester modified bamboo charcoal powder is replaced with the same weight of 300-mesh mineral powder.

[0084] Comparative Example 2

[0085] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester modified bamboo charcoal powder is replaced by bamboo fiber powder of the same weight.

[0086] Comparative Example 3

[0087] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester modified bamboo charcoal powder is replaced by silane modified bamboo charcoal powder of the same weight, and the preparation method of the silane modified bamboo charcoal powder is the same as that in Example 1.

[0088] Comparative Example 4

[0089] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester-modified bamboo charcoal powder is replaced by maleic anhydride-modified bamboo charcoal powder of the same weight. The maleic anhydride-modified bamboo charcoal powder is a self-made product, and the preparation method is as follows:

[0090] (1) The bamboo charcoal powder was washed, dried and passed through a 200-mesh sieve before being dispersed in ethanol (solid-liquid ratio 1 g / mL) to obtain a bamboo charcoal dispersion.

[0091] (2) Add silane coupling agent KH550 (5wt% of bamboo charcoal powder) to the bamboo charcoal dispersion and heat to 65℃ and stir for 3h. Volatilize the ethanol completely to obtain silane-modified bamboo charcoal powder.

[0092] (3) Mix silane-modified bamboo charcoal powder, maleic anhydride (mixed at a mass ratio of 1:0.2) and an appropriate amount of initiator DCP and place them in a twin-screw extruder for melt extrusion at 200~220℃ to obtain the hyperbranched polyester-modified bamboo charcoal powder. The screw length-to-diameter ratio is 48:1.

[0093] Comparative Example 5

[0094] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester modified bamboo charcoal powder is replaced by the same weight of hyperbranched polyester modified wood charcoal powder. The preparation method of this component is the same as that of the hyperbranched polyester modified bamboo charcoal powder in Example 1, except that the raw material is replaced by wood charcoal powder, which is carbon powder obtained by burning oak.

[0095] Comparative Example 6

[0096] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the hyperbranched polyester modified bamboo charcoal powder is replaced by the same weight of hyperbranched polyester modified coconut shell charcoal powder. The preparation method of this component is the same as that of the hyperbranched polyester modified bamboo charcoal powder in Example 1, except that the raw material is replaced by coconut shell charcoal powder, which is carbon powder obtained by burning coconut shells produced in Hainan.

[0097] Comparative Example 7

[0098] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the compatibilizer is polyethylene wax, produced by TPI in Thailand, 200C.

[0099] Comparative Example 8

[0100] A drainage asphalt mixture and its preparation method differ from Example 1 only in that the compatibilizer is maleic anhydride-grafted polyethylene, produced by Nengzhiguang as product type 218.

[0101] Example 1

[0102] To verify the sample effect of the drainage asphalt mixture described in this invention, the products prepared in each embodiment and comparative example were tested according to the JTG E20-2011 standard method: Marshall specimens and rutted slab specimens were prepared according to T0709-2011 and T0730-2011, and the permeability (permeability coefficient) and mechanical strength at 60℃ of the products were tested respectively. The leakage loss and scattering loss of the products were tested according to T0732-2011 and T0733-2011 standards to characterize their resistance to loosening. The results are shown in Table 1.

[0103] Table 1

[0104] Example 1 5800 9950 0.19 7.2 Example 2 5800 9800 0.21 7.0 Example 3 5600 9900 0.20 7.5 Example 4 5500 9250 0.24 8 Example 5 5300 9500 0.30 8.2 Example 6 5600 9900 0.20 7.2 Example 7 5400 9100 0.29 7.6 Example 8 5100 9400 0.25 7.9 Comparative Example 1 4600 8500 0.62 12.5 Comparative Example 2 4300 8350 0.70 13 Comparative Example 3 4800 9000 0.44 11.5 Comparative Example 4 4900 9300 0.35 10.5 Comparative Example 5 4900 9450 0.35 8.9 Comparative Example 6 4800 9850 0.34 9.1 Comparative Example 7 4700 8000 0.45 9.6 Comparative Example 8 4800 8400 0.56 10.1

[0105] As shown in Table 1, the drainage asphalt mixture of this invention has a very ideal permeability coefficient (the required value is above 4800 mL / min), thus exhibiting good drainage performance when used in drainage pavements. Furthermore, it demonstrates high stability during testing, with low segregation loss (required value of 0.3% or less) and low fly-through loss (required value of 10% or less), indicating excellent water and structural stability during drainage. On the other hand, the product exhibits high compressive strength at high temperatures (required value of 7000 cycles / mm or more), demonstrating that based on the reasonable combination of components, the product is suitable for high-temperature environments and will not deform under stress in high-temperature environments such as summer. According to the product performance records of Examples 1, 4, and 5, different plant fiber materials result in different product performance when used to enhance adsorption and bonding strength. In terms of water stability and high-temperature strength stability, the product prepared with bamboo fiber shows the best results. In Examples 1 and 6-8, different types of hyperbranched polyester were used in the preparation of the hyperbranched polyester-modified bamboo charcoal powder. Since the main function of the hyperbranched polyester-modified bamboo charcoal powder is to inhibit the water absorption and swelling of plant fibers and improve its compatibility with other components, the degree of compatibility varies depending on the type of hyperbranched polyester. This is especially true for high-temperature compressive strength, where terminal hydroxyl hyperbranched polyester showed the best results. In contrast, Comparative Example 1 used mineral powder added to conventional drainage asphalt mixtures instead of hyperbranched polyester bamboo charcoal powder. Clearly, this component could not provide similar protection and compatibility effects, resulting in poor water stability, low component bonding strength, and poor high-temperature compressive strength. Comparative Example 2 introduced more bamboo fiber instead of modified bamboo charcoal powder, leading to even lower water stability and component bonding strength, as well as a decrease in high-temperature compressive strength. Although Comparative Example 3 introduced modified bamboo charcoal powder, it only used a silane coupling agent for modification, which had very limited effect on improving its compatibility with other components. Therefore, its performance in all aspects was far inferior to the products in the examples. Comparative Example 4, based on the silane coupling agent modification used in Comparative Example 3, further introduced maleic anhydride to modify the bamboo charcoal powder. This improved water stability, component bonding strength, and high-temperature compressive strength to some extent, but still did not perform as well as the hyperbranched polyester-modified bamboo charcoal powder used in the corresponding examples. In Comparative Examples 5 and 6, the raw materials for the hyperbranched polyester-modified carbon powder were replaced with wood charcoal and coconut shell charcoal. Due to structural differences, these components did not improve the product strength and bonding stability as much as bamboo charcoal. In Comparative Examples 7 and 8, the products used polyethylene wax and maleic anhydride-grafted polyethylene, commonly used in existing asphalt mixtures, as compatibilizers. However, the products exhibited low dynamic stability in high-temperature rutting tests, indicating that in the formulations described in this invention, these existing compatibilizers cannot effectively adjust the high-temperature stability of the product.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A drainage asphalt mixture, characterized in that, The product comprises the following components in parts by weight: 5-15 parts asphalt, 1-3 parts styrene-butadiene-styrene block copolymer, 5-10 parts plant fiber, 5-10 parts hyperbranched polyester-modified bamboo charcoal powder, 180-190 parts graded aggregate, 1-10 parts petroleum resin, and 1-5 parts compatibilizer; wherein the compatibilizer is maleic anhydride-grafted polyethylene wax. The preparation method of the hyperbranched polyester modified bamboo charcoal powder includes the following steps: (1) Wash, dry, and pass bamboo charcoal powder through a 100-200 mesh sieve before dispersing it in an organic solvent to obtain a bamboo charcoal dispersion. (2) Add silane coupling agent to bamboo charcoal dispersion and heat to 60~70℃ and stir for 2~3h to evaporate organic solvent completely to obtain silane modified bamboo charcoal powder; (3) Mix silane-modified bamboo charcoal powder, hyperbranched polyester and initiator and put them into a screw extruder for melt extrusion at 150~200℃ to obtain the hyperbranched polyester-modified bamboo charcoal powder. The hyperbranched polyester is a hydroxyl-terminated hyperbranched polyester.

2. The drainage asphalt mixture as described in claim 1, characterized in that, The asphalt is at least one of 70# asphalt and 90# asphalt.

3. The drainage asphalt mixture as described in claim 1, characterized in that, The plant fiber is at least one of wood fiber, bamboo fiber, and plant shell fiber.

4. The drainage asphalt mixture as described in claim 3, characterized in that, The plant fiber is bamboo fiber; the method for preparing the bamboo fiber includes the following steps: (1) Cut the dried bamboo stems into thin slices, wash and dry them to obtain coarse bamboo slices; (2) The coarse bamboo pieces are crushed and processed, and the resulting powder is passed through a 200-400 mesh sieve to obtain fine bamboo powder; (3) Disperse fine bamboo powder in ethanol, sonicate for 10-15 min, and dry to obtain the bamboo fiber.

5. The drainage asphalt mixture as described in claim 1, characterized in that, The graded aggregate includes coarse aggregate and fine aggregate; the mass ratio of the coarse aggregate to the fine aggregate is (9:1) to (5:5).

6. The drainage asphalt mixture as described in claim 5, characterized in that, The coarse aggregate gradation is as follows: 1-10% of the aggregate passes through a 13.8mm sieve but not through a 12.8mm sieve; 30-45% of the aggregate passes through a 12.8mm sieve but not through an 8.8mm sieve; 30-45% of the aggregate passes through an 8.8mm sieve but not through a 5.4mm sieve; 1-5% of the aggregate passes through a 5.4mm sieve but not through a 3.3mm sieve; 1-5% of the aggregate passes through a 3.3mm sieve but not through a 1.12mm sieve; and the remaining aggregate passes through a 1.12mm sieve. The fine aggregate gradation is as follows: 100% of the aggregate passes through a 1.12mm sieve; 20-40% of the aggregate passes through a 1.12mm sieve but not through a 0.63mm sieve; 20-40% of the aggregate passes through a 0.63mm sieve but not through a 0.21mm sieve; 20-40% of the aggregate passes through a 0.21mm sieve but not through a 0.08mm sieve; and the remaining aggregate passes through a 0.08mm sieve.

7. The method for preparing the drainage asphalt mixture according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Mix asphalt, styrene-butadiene-styrene block copolymer, hyperbranched polyester modified bamboo charcoal powder, petroleum resin and compatibilizer evenly to obtain a mixture; (2) Mix the mixture with plant fiber and graded aggregate evenly to obtain the drainage asphalt mixture.

8. The method for preparing drainage asphalt mixture as described in claim 7, characterized in that, In step (1), the temperature of the mixture during preparation is 180~200℃ and the mixing rate is 150~250rpm; in step (2), the temperature of the drainage asphalt mixture during preparation is 150~180℃ and the mixing rate is 150~250rpm.