Fiber-free SMA asphalt mixture and preparation method thereof

Abstract

The invention provides a fiber-free SMA asphalt mixture and a preparation method thereof. The fiber-free SMA asphalt mixture is prepared from an asphalt mixture modifier, aggregate, modified asphalt and mineral powder, wherein the asphalt mixture modifier is prepared from the following substances in parts by weight: 100 parts of regenerated polyamide, 5-25 parts of a glycidyl methacrylate copolymer compatilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of a lubricant, 2-5 parts of a silane coupling agent, 5-20.2 parts of high oil absorption resin and 0.1-2 parts of an antioxidant; the mass ratio of the asphalt mixture modifier to the aggregate is 0.2-0.52%; the mass ratio of the modified asphalt to the aggregate is 6-7.5%. The preparation method comprises the following steps: preparing the asphalt mixture modifier; and mixing the asphalt mixture modifier, the aggregate, the modified asphalt and the mineral powder. The pavement performance such as high-temperature stability, low-temperature crack resistance and water damage resistance of the SMA asphalt mixture can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of asphalt, in particular to a fiber-free SMA asphalt mixture and a preparation method thereof. BACKGROUND

[0002] The asphalt mastic stone chip mixture (SMA) pavement has excellent high-temperature stability, low-temperature crack resistance, durability and anti-skid performance, and has become one of the most common asphalt upper layer structures of high-grade highways in China.

[0003] The SMA asphalt mixture usually needs to add fibers to stabilize the asphalt and prevent the asphalt from flowing at high temperature due to the high content of asphalt. The lignin fiber in the fiber is most widely used in the SMA mixture due to its porous surface and good oil absorption performance, but there are two problems. First, the lignin fiber is prone to cause agglomeration, resulting in insufficient uniformity of the lignin fiber in the asphalt mixture, and the mixture is prone to oil spots and oil bleeding during paving and rolling, which affects the appearance and use performance of the pavement. Second, the addition of the lignin fiber can only adsorb and stabilize the asphalt, and the improvement effect on the pavement performance of the asphalt mixture is not good enough. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a fiber-free SMA asphalt mixture and a preparation method thereof.

[0005] To achieve the above purpose, the present application provides a fiber-free SMA asphalt mixture prepared from an asphalt mixture modifier, aggregate, modified asphalt and mineral powder. The asphalt mixture modifier is prepared from the following substances by weight: 100 parts of regenerated polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of high oil absorption resin and 0.1-2 parts of antioxidant. The mass ratio of the asphalt mixture modifier to the aggregate is 0.2-0.52%, and the mass ratio of the modified asphalt to the aggregate is 6-7.5%.

[0006] In some embodiments, the mass ratio of the asphalt mixture modifier to the aggregate is 0.48-0.52%, and the single particle mass of the asphalt mixture modifier is 0.5-10 mg.

[0007] In some embodiments, the modified asphalt is SBS modified asphalt, and the mass of SBS in the SBS modified asphalt is 3%-6% of the mass of the base asphalt.

[0008] In some embodiments, the reclaimed polyamide is selected from reclaimed polyamide 6 and reclaimed polyamide 12 with a mass ratio of 1: (3-4); the mass percentage of glycidyl methacrylate in the glycidyl methacrylate copolymer compatibilizer is 5-10%, and is selected from at least one of ethylene-glycidyl methacrylate copolymer and styrene-glycidyl methacrylate copolymer; The mass ratio of the reclaimed polyamide and the glycidyl methacrylate copolymer compatibilizer is 100: (14.8-15.2).

[0009] In some embodiments, the high oil-absorbing resin is selected from polyacrylate high oil-absorbing resin.

[0010] In some embodiments, the polyacrylate high oil-absorbing resin is selected from at least one of acrylic acid-butyl acrylate-styrene, methyl methacrylate-butyl acrylate-styrene, stearyl acrylate-butyl acrylate-styrene, lauryl methacrylate-butyl acrylate-styrene, and stearyl methacrylate-butyl methacrylate-styrene; and the weight part of the polyacrylate high oil-absorbing resin is 19.8-20.2 parts.

[0011] In some embodiments, the lubricant is selected from at least one of ethylene bis-stearamide and pentaerythritol stearate; The silane coupling agent is selected from at least one of 3-ureidopropyl trimethoxysilane and bis (3-tri-ethoxysilylpropyl) tetrasulfide; The antioxidant includes at least one of N, N'-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, tris (2, 4-di-tert-butyl) phenyl phosphite, and dilauryl thiodipropionate.

[0012] The application also provides a preparation method of the fiber-free SMA asphalt mixture as described in any one of the preceding embodiments, and the preparation method comprises: Preparation of the asphalt mixture modifier; Mixing of the asphalt mixture modifier, the aggregate, the modified asphalt, and the mineral powder to obtain.

[0013] In some embodiments, the preparation of the asphalt mixture modifier comprises: Mixing of 100 parts of reclaimed polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of high oil-absorbing resin, and 0.1-2 parts of antioxidant to obtain a mixture; The mixture is melt-mixed and extruded and granulated to obtain mixture particles; wherein the extrusion and granulation is performed by using a melt booster pump, and the difference between the inlet pressure and the outlet pressure of the melt booster pump is 3-20 MPa. The mixture particles are subjected to low-temperature ultrafine pulverization and grinding to obtain the asphalt mixture modifier; the single-particle mass of the asphalt mixture modifier is 0.5-10 mg.

[0014] In some embodiments, the grinding time is 0.5-2.2 h.

[0015] As can be seen from the above, in the fiber-free SMA asphalt mixture of the embodiments of the present application, the asphalt mixture modifier not only has good strength and toughness, but also has good dispersion and oil absorption properties, which can improve the high-temperature stability, low-temperature crack resistance and water damage resistance and other road performance of the SMA asphalt mixture. At the same time, by adjusting the proportion of each raw material in the asphalt mixture modifier, the optimal asphalt content of the fiber-free SMA mixture can be adjusted, so as to be suitable for different scenes, such as ordinary regional high-grade highways, or high-grade highways or bridge pavement in cold regions and other occasions with higher requirements for the crack resistance and fatigue resistance of the asphalt mixture. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present application or related art, the following will briefly introduce the drawings needed to be used in the embodiments or related art descriptions. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0017] Figure 1 It is a schematic diagram of the fibrous and granular fibers.

[0018] Figure 2 It is a flowchart of the preparation method of the fiber-free SMA asphalt mixture of the embodiments of the present application.

[0019] Figure 3 It is a flowchart of the preparation of the asphalt mixture modifier of the embodiments of the present application.

[0020] Figure 4 It is a grading curve of the aggregate composed of aggregate, fine aggregate and mineral powder of the embodiments of the present application.

[0021] Figure 5 It is a paving effect schematic diagram of the fiber-free SMA asphalt mixture (2 cm thick) of the embodiments of the present application.

[0022] Figure 6 It is an anti-skid performance schematic diagram of the fiber-free SMA asphalt mixture (2 cm thick) of the embodiments of the present application.

[0023] Figure 7 Water sealing performance diagram of the fiber-free SMA asphalt mixture (2 cm thick) of the embodiment of the present application.

[0024] Figure 8 Schematic diagram of the existing asphalt mixture modifier and the asphalt mixture modifier of the embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below with reference to the specific embodiments and the accompanying drawings.

[0026] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood as the usual meaning understood by those skilled in the art to which the present application belongs. The terms "first", "second" and similar terms used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components.

[0027] SMA asphalt mixture is a kind of asphalt-rich mixture type formed by coarse aggregate embedding each other to form a skeleton, and then filled with asphalt, mineral powder, fiber and part of fine aggregate. In order to overcome the problem that lignin fiber can cause agglomeration and cannot significantly improve the road performance of asphalt mixture, some technologies use granular fiber instead of conventional fibrous fiber (such as Figure 1 as shown, in which the left side is fibrous fiber and the right side is granular fiber). Although the use of granular fiber instead of conventional fibrous fiber can increase the density of fiber and reduce the variability of the mixing amount to a certain extent, it cannot fundamentally solve the problem of fiber dispersion.

[0028] In some other technologies, fiber-free SMA asphalt mixture is used, mainly using high-viscosity asphalt such as rubber modified asphalt instead of conventional SBS modified asphalt, and reducing the amount of asphalt and the production temperature of asphalt mixture. The key to realizing fiber-free SMA is to maintain the strength of asphalt mastic and the skeleton filling efficiency. This is because the high temperature viscosity of SMA asphalt mixture paste decreases after the lack of fiber, and in order to avoid collapse, the first aspect needs to reduce the amount of modified asphalt, and the second aspect needs to reduce the mixing temperature. In one technology, the production temperature of SMA asphalt mixture and the amount of modified asphalt are reduced by adding a surfactant to the SMA asphalt mixture, thereby increasing the viscosity of the SMA asphalt mixture paste. Although the use of rubber modified asphalt and the like can increase the viscosity of SMA asphalt, this technical route has certain limitations: the reduction of the amount of modified asphalt has the risk of reducing the low-temperature anti-cracking performance and fatigue resistance of SMA asphalt mixture.

[0029] Based on this, the embodiment of the present application provides a fiber-free SMA asphalt mixture and a preparation method thereof. The wood fiber is replaced by an asphalt mixture modifier having the characteristics of high strength, high toughness, and high oil absorption. The amine group in the recycled polyamide reacts with the epoxy group in the glycidyl methacrylate copolymer to form a spatial network structure, and the long chain formed by the polymerization of the functional monomer of the high oil absorption resin and the special three-dimensional network structure formed after the reaction of the silane coupling agent. A good skeleton network is formed in the SMA asphalt mixture. The oil molecules can enter the three-dimensional network structure inside the high oil absorption resin through the pores on the surface of the modified asphalt oil molecules through the Van der Waals force between the lipophilic groups and the oil molecules, which can increase the content of the modified asphalt without oil bleeding. While solving the problem of uniform dispersion of poly fiber, the amount of modified asphalt is maintained or even increased, so that the SMA asphalt mixture has good road performance.

[0030] The embodiment of the present application provides a fiber-free SMA asphalt mixture, which is prepared from an asphalt mixture modifier, aggregate, modified asphalt, and mineral powder. The asphalt mixture modifier is prepared from the following substances in parts by weight: 100 parts of recycled polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of high oil absorption resin, and 0.1-2 parts of antioxidant. The mass ratio of the asphalt mixture modifier to the aggregate is 0.2-0.52%, and the mass ratio of the modified asphalt to the aggregate is 6-7.5%.

[0031] In the fiber-free SMA asphalt mixture of the embodiment of the present application, the asphalt mixture modifier not only has good strength and toughness, but also has good dispersion and oil absorption properties, which can improve the high-temperature stability, low-temperature crack resistance, and water damage resistance of the SMA asphalt mixture. At the same time, by adjusting the proportion of each raw material in the asphalt mixture modifier, the optimal asphalt dosage of the fiber-free SMA mixture can be adjusted, so as to be suitable for different scenes, such as ordinary areas, high-grade highways, or high-grade highways or bridge pavement in cold regions, and other occasions with higher requirements for crack resistance and fatigue resistance of asphalt mixture.

[0032] In some embodiments, the recycled polyamide can be selected from recycled polyamide 6 and recycled polyamide 12 with a mass ratio of 1: (3-4). The recycled polyamide 6 is a recycled polyamide with high tensile strength, thermal stability, and wear resistance, but relatively poor toughness. The recycled polyamide 12 is a recycled polyamide with good chemical resistance, impact toughness, and processing performance. The mixture of recycled polyamide 6 and recycled polyamide 12 with this mass ratio can make the fiber-free SMA asphalt mixture have good strength and toughness.

[0033] In some embodiments, the glycidyl methacrylate copolymer compatibilizer can be present in the asphalt mixture modifier in an amount of 5, 12, 15, 18, 20, 22, 25, or a range having any of the foregoing as upper and lower limits.

[0034] In some embodiments, the glycidyl methacrylate copolymer compatibilizer can have a glycidyl methacrylate content of 5-10%, for example, can be selected from at least one of ethylene-glycidyl methacrylate copolymer and styrene-glycidyl methacrylate copolymer.

[0035] In some embodiments, the recycled polyamide 6 and the recycled polyamide 12 can be present in the recycled polyamide in a mass ratio of 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, or 1:4, etc. The glycidyl methacrylate copolymer compatibilizer can have a glycidyl methacrylate content of 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range having any of the foregoing as upper and lower limits. The recycled polyamide and the glycidyl methacrylate copolymer compatibilizer can be present in a mass ratio of 100:(14.8-15.2), for example, 100:14.8, 100:15, or 100:15.2, etc. The recycled polyamide and the glycidyl methacrylate copolymer compatibilizer in such a mass ratio can form a good skeleton network of the chemical reaction between the amine groups in the polyamide and the epoxy groups in the glycidyl methacrylate copolymer, enhance the interfacial bonding force between the fiberless SMA asphalt mixture and the original road surface, and make the mechanical strength of the fiberless SMA asphalt mixture good, thereby making the fiberless SMA asphalt mixture have good road performance. Avoiding the decrease in the mechanical strength of the skeleton network caused by too high or too low mass ratio of the recycled polyamide and the glycidyl methacrylate copolymer compatibilizer.

[0036] In some embodiments, the waste tire rubber powder can have a particle size of 80 mesh. The waste tire rubber powder can be present in the asphalt mixture modifier in an amount of 5 parts, 7 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, or a range having any of the foregoing as upper and lower limits.

[0037] In some embodiments, the lubricant can be selected from at least one of ethylene bis-stearamide and pentaerythritol stearate. The lubricant can be present in the asphalt mixture modifier in an amount of 1 part, 3 parts, 5 parts, 7 parts, 8 parts, or a range having any of the foregoing as upper and lower limits. The lubricant in such an amount can help the recycled polyamide and the waste tire rubber powder to achieve good melting dispersion.

[0038] In some embodiments, the silane coupling agent can be selected from at least one of 3-ureidopropyl trimethoxysilane and bis(3-tri-ethoxysilylpropyl) tetrasulfide. The silane coupling agent can be present in the asphalt mixture modifier in an amount of 2 parts, 3 parts, 4 parts, 5 parts, or a range having any of the foregoing as upper and lower limits.

[0039] In some embodiments, the high oil absorption resin can be a polyacrylate high oil absorption resin, which can be formed by free radical initiated emulsion polymerization or suspension polymerization of acrylate monomers. The polyacrylate high oil absorption resin can be selected from at least one of acrylic acid-butyl acrylate-styrene, methyl methacrylate-butyl acrylate-styrene, stearyl acrylate-butyl acrylate-styrene, lauryl methacrylate-butyl acrylate-styrene, and stearyl methacrylate-butyl methacrylate-styrene. The polyacrylate high oil absorption resin can be present in the asphalt mixture modifier in an amount of 5 parts, 7 parts, 10 parts, 12 parts, 15 parts, 17 parts, 19 parts, 19.8 parts, 20 parts, 20.2 parts, or a range having any of the foregoing as upper and lower limits.

[0040] In some embodiments, the high oil absorption resin can be present in the asphalt mixture modifier in an amount of 19.8-20.2 parts, such as 19.8 parts, 19.9 parts, 20 parts, 20.1 parts, or 20.2 parts, or a range having any of the foregoing as upper and lower limits. Such an amount of high oil absorption resin can improve the asphalt absorption, low temperature cracking resistance, and water damage resistance of the asphalt mixture modifier as much as possible, while avoiding excessive absorption of the modified asphalt due to a high content of the high oil absorption resin, which can affect the road performance of the asphalt mixture.

[0041] In some embodiments, the antioxidant can be selected from at least one of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, tris(2,4-di-tert-butyl) phenyl phosphite, and dilauryl thiodipropionate. In some embodiments, the antioxidant can be present in the asphalt mixture modifier in an amount of 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, or a range having any of the foregoing as upper and lower limits.

[0042] In some embodiments, the asphalt mixture modifier can account for 0.48-0.52% of the mass of the aggregate, such as 0.48%, 0.49%, 5.0%, 0.51%, or 0.52%. The single-particle mass of the asphalt mixture modifier is 0.5-10 mg, such as 0.5 mg, 1 mg, 1.5 mg, 2 mg, 2.5 mg, 3 mg, 3.5 mg, 4 mg, 4.5 mg, 5 mg, 5.5 mg, 6 mg, 6.5 mg, 7 mg, 7.5 mg, 8 mg, 8.5 mg, 9 mg, 9.5 mg, or 10 mg. Pictures of the asphalt mixture modifier are shown in Figure 8 Figure 8 In some embodiments, the left black particles are existing asphalt mixture modifiers, and the right transparent particles are the asphalt mixture modifiers prepared in the embodiments of the present application, with a single-particle mass of 0.5-10 mg. The asphalt mixture modifiers can improve the optimum asphalt-aggregate ratio and low-temperature performance of the obtained fiber-free SMA asphalt mixture, appropriately reduce the high-temperature performance, and make the fiber-free SMA asphalt mixture have good overall road performance.

[0043] In some embodiments, the aggregate can include coarse aggregate and fine aggregate. It should be understood that the embodiments of the present application do not involve improvements to the specific components of the aggregate in existing SMA asphalt mixtures and the corresponding amounts of the components.

[0044] In some embodiments, the modified asphalt can be SBS modified asphalt. The mass of SBS in the SBS modified asphalt is 3%-6% of the mass of the base asphalt. It should be understood that the embodiments of the present application do not involve improvements to the specific components of the existing SBS modified asphalt and the corresponding amounts of the components. The embodiments of the present application do not involve improvements to the specific components of the existing mineral powder and the corresponding amounts of the components.

[0045] Based on the same inventive concept, the present application also provides a preparation method of a fiber-free SMA asphalt mixture corresponding to any of the above-mentioned embodiments.

[0046] Referring to Figure 2 , the preparation method of the fiber-free SMA asphalt mixture can include: Step S100, preparing the asphalt mixture modifier. The asphalt mixture modifier is prepared from the following substances in parts by weight: 100 parts of recycled polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of high oil absorption resin, and 0.1-2 parts of antioxidant.

[0047] ​Step S200, the asphalt mixture modifier, the aggregate, the modified asphalt and the mineral powder are mixed to obtain a fiberless SMA asphalt mixture. The asphalt mixture modifier accounts for 0.2-0.52% of the mass of the aggregate; the modified asphalt accounts for 6-7.5% of the mass of the aggregate.

[0048] In some embodiments, the asphalt mixture modifier is prepared by the following steps: Figure 3 In step S100, the asphalt mixture modifier can be prepared by the following steps: Step S110, 100 parts of recycled polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of high oil absorption resin and 0.1-2 parts of antioxidant are mixed to obtain a mixture. The mixing temperature can be 80-100℃.

[0049] Step S120, the mixture is melt-mixed and extruded and granulated to obtain a mixture granule; wherein a twin-screw extruder can be used for melt-mixing. The barrel temperature of the twin-screw extruder can be 220-260℃. The screw rotation speed of the twin-screw extruder is 100-250r / min. Extrusion granulation can be carried out by using a melt booster pump, and the difference between the inlet pressure and the outlet pressure of the melt booster pump can be 3-20MPa. By using a melt booster pump for extrusion granulation, the uniformity of the asphalt mixture modifier obtained can be improved. Generally, cooling and drying are required after extrusion granulation.

[0050] Step S130, the mixture granule is subjected to low-temperature ultrafine pulverization and grinding to obtain the asphalt mixture modifier; the single-particle mass of the asphalt mixture modifier is 0.5-10mg. By using a low-temperature ultrafine pulverization process, the dispersibility of the asphalt mixture modifier granule in the asphalt mixture can be improved.

[0051] The asphalt mixture modifier prepared by the above preparation method has the advantages of simple preparation method, controllable material and production cost, and easy production and application. In some embodiments, in step S130, the grinding time can be 0.5-2h. This grinding time can make the modifier have a larger specific area and better absorb the modified asphalt.

[0052] In some embodiments, in step S200, the asphalt mixture modifier and the aggregate can be first put into a mixing pot at 180℃ and dry mixed uniformly, then the SBSSBS modified asphalt is added and mixed uniformly, and finally the mineral powder is added and mixed uniformly, to finally obtain a fiberless SMA asphalt mixture. The dry mixing time can be 90s, and the mixing time can also be 90s.

[0053] The preparation method of the fiber-free SMA asphalt mixture of the above embodiment is used to realize the preparation of the corresponding fiber-free SMA asphalt mixture in any of the preceding embodiments, and has the beneficial effects of the corresponding fiber-free SMA asphalt mixture embodiment, which will not be repeated here.

[0054] The technical solutions of the present application will be further described in combination with the specific embodiments.

[0055] The experimental methods in the following embodiments are all conventional methods unless otherwise specified.

[0056] The test materials used in the following embodiments are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0057] In the following embodiments, the particle size of the waste tire rubber powder is 80 mesh. In the ethylene-glycidyl methacrylate copolymer / styrene-glycidyl methacrylate copolymer, the mass percentage of glycidyl methacrylate is 6%. The screw rotation speed of the twin-screw extruder is 150 r / min. The difference between the inlet pressure and the outlet pressure of the melt booster pump is 10 MPa. The aggregate gradation curve composed of aggregate, fine aggregate, and mineral powder is as shown in Figure 4 The coarse aggregate is basalt, and the mass percentage of the coarse aggregate in the aggregate is 70%. The fine aggregate and the mineral powder are limestone, the mass percentage of the fine aggregate in the aggregate is 20%, and the mass percentage of the mineral powder in the aggregate is 10%. The mass of SBS in the SBS modified asphalt is 4% of the mass of the base asphalt, and the base asphalt is 70# base asphalt.

[0058] Embodiment 1 Preparation of the asphalt mixture modifier, comprising: weighing raw materials, the raw materials comprising ingredients in the following weight parts: 25 parts of recycled polyamide 6, 75 parts of recycled polyamide 12, 25 parts of styrene-glycidyl methacrylate copolymer compatibilizer, 5 parts of waste tire rubber powder, 1 part of pentaerythritol stearate, 2 parts of bis(3-tri-ethoxysilylpropyl) tetrasulfide, 5 parts of acrylic acid-butyl acrylate-styrene (HPAA-BA-St), 0.5 parts of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine antioxidant. The raw materials are uniformly mixed at 80°C to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder, and reacted and extruded by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 260°C; the above modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 1 h, and the single particle mass of the modifier material after drying is 5 mg.

[0059] The asphalt mixture is prepared in the laboratory using the above asphalt mixture modifier, and the aggregate gradation curve used is as shown in Figure 4The asphalt mixture modifier material is mixed with 12000g aggregate in a mixing kettle at 180℃ for 90 seconds, 720g SBS modified asphalt is added and mixed for 90 seconds, and mineral powder is added and mixed for 90 seconds to obtain the fiber-free SMA asphalt mixture.

[0060] Example 2 The asphalt mixture modifier is prepared by weighing raw materials including ingredients in the following weight fractions: 25 parts of recycled polyamide 6, 75 parts of recycled polyamide 12, 5 parts of ethylene-glycidyl methacrylate copolymer compatibilizer, 5 parts of waste tire rubber powder, 1 part of pentaerythritol stearate, 2 parts of bis(3-tri-ethoxysilylpropyl) tetrasulfide, 5 parts of methyl methacrylate-butyl acrylate-styrene (MMA-BA-St), and 0.5 parts of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine antioxidant; the raw materials are uniformly mixed at 80℃ to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder and reacted by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 260℃; the modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 1h, and the single-particle mass of the modifier material after drying is 5mg.

[0061] The asphalt mixture modifier is prepared by weighing raw materials including ingredients in the following weight fractions: 25 parts of recycled polyamide 6, 75 parts of recycled polyamide 12, 5 parts of ethylene-glycidyl methacrylate copolymer compatibilizer, 5 parts of waste tire rubber powder, 1 part of pentaerythritol stearate, 2 parts of bis(3-tri-ethoxysilylpropyl) tetrasulfide, 5 parts of methyl methacrylate-butyl acrylate-styrene (MMA-BA-St), and 0.5 parts of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine antioxidant; the raw materials are uniformly mixed at 80℃ to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder and reacted by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 260℃; the modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 1h, and the single-particle mass of the modifier material after drying is 5mg. Figure 4 The asphalt mixture modifier is mixed with 12000g aggregate in a mixing kettle at 180℃ for 90 seconds, 720g SBS modified asphalt is added and mixed for 90 seconds, and mineral powder is added and mixed for 90 seconds to obtain the fiber-free SMA asphalt mixture.

[0062] Example 3 The asphalt mixture modifier is prepared by weighing raw materials including ingredients in the following weight fractions: 25 parts of recycled polyamide 6, 75 parts of recycled polyamide 12, 5 parts of ethylene-glycidyl methacrylate copolymer compatibilizer, 5 parts of waste tire rubber powder, 1 part of pentaerythritol stearate, 2 parts of bis(3-tri-ethoxysilylpropyl) tetrasulfide, 5 parts of methyl methacrylate-butyl acrylate-styrene (MMA-BA-St), and 0.5 parts of N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine antioxidant; the raw materials are uniformly mixed at 80℃ to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder and reacted by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 260℃; the modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 1h, and the single-particle mass of the modifier material after drying is 5mg.

[0063] The asphalt mixture modifier described above was used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is shown in Figure 4 The 36 g of the above modifier and 12000 g of aggregate were put into a mixing kettle at 180 °C and dry mixed for 90 seconds, 744 g of SBS modified asphalt was added and mixed for 90 seconds, and then mineral powder was added and mixed for 90 seconds to obtain fiber-free SMA asphalt mixture.

[0064] Example 4 The asphalt mixture modifier was prepared by weighing the raw materials, which included ingredients in the following weight fractions: 20 parts of recycled polyamide 6, 80 parts of recycled polyamide 12, 15 parts of ethylene-glycidyl methacrylate copolymer compatibilizer, 20 parts of waste tire rubber powder, 8 parts of ethylene bis-stearamide, 5 parts of 3-ureidopropyl trimethoxysilane, 5 parts of stearyl acrylate-butyl acrylate-styrene (SA-BA-St), 2 parts of tris(2,4-di-t-butyl) phenyl phosphite and dilauryl thiodipropionate antioxidant; the raw materials were uniformly mixed at 100 °C to obtain a first mixture; the first mixture was melt-mixed using a twin-screw extruder, and reacted and extruded using a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder was 220 °C; the above modifier particles were crushed and ground by low-temperature ultrafine crushing process, the grinding time was 0.5 h, and after drying, the single particle mass of the modifier material was 10 mg.

[0065] The asphalt mixture modifier described above was used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is shown in Figure 4 The 36 g of the above modifier and 12000 g of aggregate were put into a mixing kettle at 180 °C and dry mixed for 90 seconds, 744 g of SBS modified asphalt was added and mixed for 90 seconds, and then mineral powder was added and mixed for 90 seconds to obtain fiber-free SMA asphalt mixture.

[0066] Example 5 Preparation of asphalt mixture modifier, comprising: weighing raw materials, the raw materials include ingredients in the following weight parts: 20 parts of recycled polyamide 6, 80 parts of recycled polyamide 12, ethylene-glycidyl methacrylate copolymer compatibilizer 15 parts, waste tire rubber powder 20 parts, ethylene bis-stearamide 8 parts, 3-urea propyl trimethoxysilane 5 parts, lauryl methacrylate-butyl acrylate-styrene (LMA-BA-St) 10 parts, tri(2,4-di-tert-butyl) phenyl phosphite and dilauryl thiodipropionate antioxidant 2 parts; the raw materials are mixed uniformly at 100 DEG C to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder, and is reacted and extruded by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 220 DEG C; the above modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 0.5 h, and the single particle mass of the modifier material is 10 mg after drying.

[0067] The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in Figure 4 The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in

[0068] Example 6 Preparation of asphalt mixture modifier, comprising: weighing raw materials, the raw materials include ingredients in the following weight parts: 20 parts of recycled polyamide 6, 80 parts of recycled polyamide 12, ethylene-glycidyl methacrylate copolymer compatibilizer 15 parts, waste tire rubber powder 20 parts, ethylene bis-stearamide 8 parts, 3-urea propyl trimethoxysilane 5 parts, lauryl methacrylate-butyl acrylate-styrene (LMA-BA-St) 10 parts, tri(2,4-di-tert-butyl) phenyl phosphite and dilauryl thiodipropionate antioxidant 2 parts; the raw materials are mixed uniformly at 100 DEG C to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder, and is reacted and extruded by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 220 DEG C; the above modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 0.5 h, and the single particle mass of the modifier material is 10 mg after drying.

[0069] The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in Figure 4 The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in

[0070] Example 7 Preparation of asphalt mixture modifier, comprising: weighing raw materials, the raw materials include ingredients in the following weight parts: 20 parts of recycled polyamide 6, 80 parts of recycled polyamide 12, ethylene-glycidyl methacrylate copolymer compatibilizer 15 parts, waste tire rubber powder 20 parts, ethylene bis-stearamide 8 parts, 3-urea propyl trimethoxysilane 5 parts, lauryl methacrylate-butyl acrylate-styrene (LMA-BA-St) 10 parts, tris(2,4-di-tert-butyl) phenyl phosphite and dilauryl thiodipropionate antioxidant 2 parts; the raw materials are mixed uniformly at 100℃ to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder, and is reacted and extruded by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 220℃; the above modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 0.5h, and the single particle mass of the modifier material after drying is 10mg.

[0071] The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in Figure 4 60g of the above modifier and 12000g of aggregate are put into a mixing kettle at 180℃ for dry mixing for 90 seconds, 876g of SBS modified asphalt is added and mixed for 90 seconds, and mineral powder is added and mixed for 90 seconds to obtain fiber-free SMA asphalt mixture.

[0072] Example 8 Preparation of asphalt mixture modifier, comprising: weighing raw materials, the raw materials include ingredients in the following weight parts: 20 parts of recycled polyamide 6, 80 parts of recycled polyamide 12, ethylene-glycidyl methacrylate copolymer compatibilizer 15 parts, waste tire rubber powder 20 parts, ethylene bis-stearamide 8 parts, 3-urea propyl trimethoxysilane 5 parts, lauryl methacrylate-butyl acrylate-styrene (LMA-BA-St) 10 parts, tris(2,4-di-tert-butyl) phenyl phosphite and dilauryl thiodipropionate antioxidant 2 parts; the raw materials are mixed uniformly at 100℃ to obtain a first mixture; the first mixture is melt-mixed by a twin-screw extruder, and is reacted and extruded by a melt booster pump to obtain modifier particles, the barrel temperature of the twin-screw extruder is 220℃; the above modifier particles are crushed and ground by a low-temperature ultrafine crushing process, the grinding time is 0.5h, and the single particle mass of the modifier material after drying is 10mg.

[0073] The above asphalt mixture modifier is used to prepare asphalt mixture in the laboratory, and the mineral aggregate grading curve used is as shown in Figure 4As shown. 36g of the above modifier and 12000g of aggregate were put into a mixing pot at 180℃ and dry-mixed for 90 seconds. 900g of SBS modified asphalt was added and mixed for 90 seconds. Then mineral powder was added and mixed for 90 seconds to obtain fiber-free SMA asphalt mixture.

[0074] Comparative Example 1 Preparation of fiber-free SMA asphalt mixture. Using methods such as... Figure 4 The aggregate gradation curve shown is used to prepare asphalt mixtures in the laboratory without adding any modifiers. 12,000g of aggregate is put into a mixing pot at 180℃ and dry-mixed for 90 seconds. 660g of SBS modified asphalt is added and mixed for 90 seconds. Then, mineral powder is added and mixed for 90 seconds to obtain ordinary fiber-free SMA asphalt mixture.

[0075] Comparative Example 2 Prepare fiber-free SMA asphalt mixture. The difference from Example 1 is that the asphalt mixture modifier material does not contain styrene-glycidyl methacrylate copolymer compatibilizer; all other steps are the same as in Example 1.

[0076] Comparative Example 3 Preparation of fiber-free SMA asphalt mixture. The method used is as follows: Figure 5 to Figure 7 The aggregate gradation curve shown is used to prepare asphalt mixtures in the laboratory. 36g of wood fiber and 12000g of aggregate are put into a mixing pot at 180℃ and dry-mixed for 90 seconds. 720g of SBS modified asphalt is added and mixed for 90 seconds. Then, mineral powder is added and mixed for 90 seconds to obtain ordinary fiber-free SMA asphalt mixture.

[0077] Comparative Example 4 Prepare fiber-free SMA asphalt mixture. The difference from Example 4 is that the asphalt mixture modifier does not contain octadecyl acrylate-butyl acrylate-styrene (SA-BA-St), and the amount of SBS modified asphalt is 672g. The rest of the steps are the same as in Example 4.

[0078] Test methods: According to the test methods in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the fiber-free SMA asphalt mixtures prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to relevant performance tests. The optimal asphalt-aggregate ratio of the asphalt mixture was evaluated using segregation loss and water immersion scattering loss tests. The high-temperature deformation resistance of the asphalt mixture was evaluated using Marshall stability and 60℃ dynamic stability indices. The low-temperature crack resistance of the asphalt mixture was evaluated using a -10℃ low-temperature bending test. The water damage resistance of the asphalt mixture was evaluated using the freeze-thaw splitting strength ratio.

[0079] Test results: The test results are shown in Tables 1 to 3 below, and Figure 5As shown in the table. Table 1 shows the test results of Examples 1 to 3 and Comparative Examples 1 to 2. Figure 6 , Figure 7 as well as Figure 5 to Figure 7 The anti-skid and water-sealing properties of the pavement prepared from the fiberless SMA asphalt mixture obtained in Example 5 are shown.

[0080] Table 1. Test results of Examples 1 to 3 and Comparative Examples 1 to 2

[0081] Table 2 shows the test results of Examples 4 to 8 and Comparative Examples 3 to 4.

[0082] Table 3 Test results of Examples 5 to 7

[0083] Results Analysis: As shown in Tables 1, 2, and 3, the fiber-free SMA asphalt mixtures with added asphalt mixture modifiers in Examples 1 to 9 exhibit good high-temperature deformation resistance. Low-temperature crack resistance and water damage resistance, etc. ​ As shown, the pavement formed by the fiberless SMA asphalt mixture prepared in Examples 1 to 9 has good anti-skid and water-sealing properties. Even with a paving thickness of only 2cm, the pavement texture depth can still reach 0.9mm, which is higher than the requirement of not less than 0.55mm. The permeability coefficient is almost 0ml / min, which is higher than the requirement of not more than 120ml / min.

[0084] As shown in Table 1, compared with Comparative Example 1, it can be seen that the fiberless SMA asphalt mixture obtained by adding the asphalt mixture modifier can improve the optimum oil-stone ratio and deformation resistance of the fiberless SMA asphalt mixture, and can reduce the water immersion scattering loss of the fiberless SMA asphalt mixture. Compared with Comparative Example 1, it can be seen that the content of the glycidyl methacrylate copolymer compatibilizer in the asphalt mixture modifier has a greater influence on the road performance of the fiberless SMA asphalt mixture. Among them, when the ratio of the polyamide reclaimed material to the glycidyl methacrylate copolymer compatibilizer is 100:15, the road performance of the fiberless SMA asphalt mixture is the best. At this time, the spatial network structure formed by the chemical reaction between the amine group in the polyamide reclaimed material and the epoxy group in the glycidyl methacrylate copolymer can form the best skeleton network, and can enhance the interfacial bonding force between the fiberless SMA asphalt mixture and the original road surface. When the ratio of the polyamide reclaimed material to the glycidyl methacrylate copolymer compatibilizer is too high or too low, the mechanical strength of the asphalt mixture will be affected to some extent. As shown in Table 2, compared with Comparative Example 3, it can be seen that the asphalt mixture modifier has better asphalt absorption effect, low-temperature anti-cracking and water damage resistance than the wood fiber at the same dosage, and the performance difference increases with the increase of the content of the superabsorbent resin. The reason is that the superabsorbent resin, as a polymeric high molecular material, forms a special three-dimensional network structure through the reaction of long chains formed by different functional monomers and silane coupling agents, and the Van der Waals force between the lipophilic groups and oil molecules. The asphalt oil molecules can enter the network structure inside the resin through the pores on the surface of the resin, achieve the effect of oil absorption and oil preservation, and increase the content of modified asphalt in the fiberless SMA asphalt mixture without oil bleeding. In addition, compared with the wood fiber, the fiberless SMA asphalt mixture added with the asphalt mixture modifier has smaller water immersion scattering loss and greater Marshall stability. Among them, the dynamic stability of the fiberless SMA asphalt mixture added with the asphalt mixture modifier can be more than 3 times that of the fiberless SMA asphalt mixture added with the wood fiber, and the mechanical strength is obviously improved.

[0085] As shown in Table 2, compared with Comparative Example 3, it can be seen that the asphalt mixture modifier has better asphalt absorption effect, low-temperature anti-cracking and water damage resistance than the wood fiber at the same dosage, and the performance difference increases with the increase of the content of the superabsorbent resin. The reason is that the superabsorbent resin, as a polymeric high molecular material, forms a special three-dimensional network structure through the reaction of long chains formed by different functional monomers and silane coupling agents, and the Van der Waals force between the lipophilic groups and oil molecules. The asphalt oil molecules can enter the network structure inside the resin through the pores on the surface of the resin, achieve the effect of oil absorption and oil preservation, and increase the content of modified asphalt in the fiberless SMA asphalt mixture without oil bleeding. In addition, compared with the wood fiber, the fiberless SMA asphalt mixture added with the asphalt mixture modifier has smaller water immersion scattering loss and greater Marshall stability. Among them, the dynamic stability of the fiberless SMA asphalt mixture added with the asphalt mixture modifier can be more than 3 times that of the fiberless SMA asphalt mixture added with the wood fiber, and the mechanical strength is obviously improved.

[0086] As can be seen from Table 3, comparison of Example 5 and Example 6 shows that the low-temperature ultrafine pulverization and grinding process of the asphalt mixture modifier also has certain influence on the asphalt absorption effect of the asphalt mixture modifier. With the prolongation of the grinding time, the specific surface area of the asphalt mixture modifier is larger, and the asphalt absorption amount is also more.

[0087] As can be seen from the comparison of Example 5 and Example 7, when the mixing amount of the asphalt mixture modifier is increased from 0.3% to 0.5%, the optimum oil-stone ratio of the obtained fiberless SMA asphalt mixture is also greatly increased from 6.4% to 7.3%, the high-temperature performance is decreased to a certain extent, the low-temperature performance is improved, and the comprehensive road performance is excellent.

[0088] The above results show that the fiberless SMA asphalt mixture prepared by using the asphalt mixture modifier instead of wood fiber in the embodiments of the present application can improve the high-temperature stability, low-temperature crack resistance and water damage resistance and other road performances of the obtained fiberless SMA asphalt mixture, and the obtained fiberless SMA asphalt mixture has anti-skid and water sealing properties. In addition, the problem of uneven dispersion of the traditional fiber modifier in the asphalt mixture mixing process can be effectively avoided.

[0089] It should be understood by those skilled in the art that the above discussion of any of the embodiments is only exemplary and is not intended to imply that the scope (including claims) of the present disclosure is limited to these examples; the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the embodiments of the present disclosure as described above. In order to be brief, they are not provided in details.

[0090] Although the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description.

[0091] The embodiments of the present disclosure are intended to cover all such alternatives, modifications and variations which fall within the broad scope of the appended claims. Accordingly, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A fiber-free SMA asphalt mixture, characterized in that, It is prepared from asphalt mixture modifier, aggregate, modified asphalt and mineral powder; The asphalt mixture modifier is prepared from the following components by weight: 100 parts recycled polyamide, 5-25 parts glycidyl methacrylate copolymer compatibilizer, 5-20 parts waste tire rubber powder, 1-8 parts lubricant, 2-5 parts silane coupling agent, 5-20.2 parts high oil absorption resin, and 0.1-2 parts antioxidant. The asphalt mixture modifier accounts for 0.2-0.52% of the mass of the aggregate; the modified asphalt accounts for 6-7.5% of the mass of the aggregate.

2. The fiber-free SMA asphalt mixture according to claim 1, characterized in that, The asphalt mixture modifier accounts for 0.48-0.52% of the mass of the aggregate; the mass of a single particle of the asphalt mixture modifier is 0.5-10 mg.

3. The fiber-free SMA asphalt mixture according to claim 1, characterized in that, The modified asphalt is SBS modified asphalt, and the mass of SBS in the SBS modified asphalt is 3%-6% of the mass of the base asphalt.

4. The fiber-free SMA asphalt mixture according to claim 1, characterized in that, The recycled polyamide is selected from recycled polyamide 6 and recycled polyamide 12 in a mass ratio of 1:(3-4); the mass percentage of glycidyl methacrylate in the glycidyl methacrylate copolymer compatibilizer is 5-10%, selected from at least one of ethylene-glycidyl methacrylate copolymer and styrene-glycidyl methacrylate copolymer. The mass ratio of the recycled polyamide to the glycidyl methacrylate copolymer compatibilizer is 100:(14.8-15.2).

5. The fiber-free SMA asphalt mixture according to claim 1, characterized in that, The super oil-absorbing resin is selected from polyacrylate super oil-absorbing resins.

6. The fiber-free SMA asphalt mixture according to claim 5, characterized in that, The polyacrylate super absorbent resin is selected from at least one of acrylate-butyl acrylate-styrene, methyl methacrylate-butyl acrylate-styrene, octadecyl acrylate-butyl acrylate-styrene, lauryl methacrylate-butyl acrylate-styrene, and octadecyl methacrylate-butyl methacrylate-styrene; the polyacrylate super absorbent resin has a weight of 19.8-20.2 parts.

7. The fiber-free SMA asphalt mixture according to claim 1, characterized in that, The lubricant is selected from at least one of ethylene bis-stearamide and pentaerythritol stearate; The silane coupling agent is selected from at least one of 3-ureapropyltrimethoxysilane and bis(3-tri-ethoxysilylpropyl)tetrasulfide; The antioxidant comprises at least one of the following: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, tris(2,4-di-tert-butyl)phosphite, and dilauryl thiodipropionate.

8. A method for preparing fiber-free SMA asphalt mixture as described in any one of claims 1-7, characterized in that, The preparation method includes: Prepare the asphalt mixture modifier; The asphalt mixture modifier, the aggregate, the modified asphalt, and the mineral powder are mixed together to obtain the mixture.

9. The method for preparing fiber-free SMA asphalt mixture according to claim 8, characterized in that, The preparation of the asphalt mixture modifier includes: Mix 100 parts of recycled polyamide, 5-25 parts of glycidyl methacrylate copolymer compatibilizer, 5-20 parts of waste tire rubber powder, 1-8 parts of lubricant, 2-5 parts of silane coupling agent, 5-20.2 parts of super oil-absorbing resin and 0.1-2 parts of antioxidant to obtain a mixture. The mixture is melt-blended and extruded to obtain mixture particles; wherein the extrusion granulation is carried out using a melt booster pump, and the difference between the inlet pressure and the outlet pressure of the melt booster pump is 3-20 MPa. The asphalt mixture particles are subjected to low-temperature ultrafine pulverization and grinding to obtain the asphalt mixture modifier; the mass of a single particle of the asphalt mixture modifier is 0.5-10 mg.

10. The method for preparing fiber-free SMA asphalt mixture according to claim 9, characterized in that, The grinding time is 0.5-2.2 hours.

Images