A high-toughness asphalt mixture modified from waste plastics and rubber and its application

Abstract

This invention discloses a high-toughness asphalt mixture modified from waste plastics and rubber, and its application. It relates to the field of asphalt mixture preparation technology, comprising 80-150 parts of base asphalt, 2-8 parts of modified waste plastic particles, 4-12 parts of activated waste tire rubber powder, 100-150 parts of aggregate, and 30-40 parts of mineral filler. This invention adds silane-coupled waste plastic particles and microwave-activated waste tire rubber powder to the asphalt mixture, limiting the mass ratio of modified waste plastic particles to activated waste tire rubber powder to 1:(1.5~2). The aggregate and mineral filler fully fill the gaps, synergistically solving the defects of high low-temperature brittleness and insufficient high-temperature performance in asphalt. This results in a mixture with excellent high-temperature stability and low-temperature crack resistance, and significantly improved performance reproducibility.

Description

Technical Field This invention relates to the field of asphalt mixture preparation technology, specifically to a high-toughness asphalt mixture based on waste plastic and rubber composite modification and its application. Background Technology

[0001] In the field of road construction, asphalt pavement has long dominated high-grade highways and urban roads due to its advantages such as good smoothness, driving comfort, and convenient maintenance. However, with the continuous growth of traffic volume, the increase in the proportion of heavy-duty vehicles, and the frequent occurrence of extreme weather, traditional asphalt pavement faces problems of insufficient durability, such as high-temperature rutting, low-temperature cracking, and fatigue damage, which seriously affect the service life and traffic quality of roads.

[0002] The massive accumulation of solid waste globally has become a prominent environmental problem. The recycling rates of waste plastics and waste tire rubber are particularly low, leading not only to resource waste but also to a series of environmental risks such as soil pollution and fire hazards. Against this backdrop, the application of solid waste materials such as waste plastics and waste tire rubber in asphalt modification has become a research hotspot and development trend in the field of road engineering materials.

[0003] In summary, current technologies for utilizing waste plastics and waste tire rubber are mostly limited to single modification models, failing to fully leverage the performance advantages of these two solid waste materials and unable to overcome the technical shortcomings of using them individually. Therefore, the industry urgently needs an effective technical solution that overcomes the deficiencies of single solid waste modification while simultaneously considering the comprehensive performance of asphalt mixtures, including high-temperature stability, low-temperature crack resistance, and durability, while reducing processing energy consumption and production costs. This would truly achieve high-value-added utilization of solid waste resources and solve the two major problems of insufficient durability of traditional asphalt pavements and solid waste pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a high-toughness asphalt mixture based on waste plastic and rubber composite modification and its application, in order to overcome the defects of low waste utilization rate and unstable asphalt performance.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a high-toughness asphalt mixture modified from waste plastics and rubber, wherein the asphalt mixture comprises the following components by weight fraction: The composition consists of 80-150 parts base asphalt, 2-8 parts modified waste plastic granules, 4-12 parts activated waste tire rubber powder, 100-150 parts aggregate, and 30-40 parts mineral filler. The modified waste plastic particles are waste polyethylene treated with a surface silane coupling agent. The activated waste tire rubber powder is waste tire rubber powder that has undergone microwave activation treatment. The mass ratio of the modified waste plastic particles to the activated waste tire rubber powder is 1:(1.5~2).

[0006] Currently, there are existing research and application practices in the industry regarding the modification of asphalt using single solid waste materials. Among these, waste plastics, due to their excellent thermoplasticity and mechanical properties, can effectively improve the high-temperature stability and stiffness of asphalt mixtures and reduce the occurrence of high-temperature rutting. However, waste plastics have poor compatibility with the asphalt matrix; simply adding them can easily lead to agglomeration in the asphalt, resulting in a significant decrease in the low-temperature flexibility and toughness of the mixture, weakened crack resistance, and insufficient adhesion to aggregates, making them prone to spalling under long-term water damage, thus limiting their large-scale application. On the other hand, waste tire rubber powder, as an elastomer material, can significantly improve the low-temperature crack resistance, fatigue resistance, and elastic recovery ability of asphalt mixtures after modification, enhancing the pavement's resistance to damage. However, the dense molecular structure of waste tire rubber powder results in poor swelling and dispersion effects in asphalt, requiring higher processing temperatures and longer processing times. This not only increases energy consumption and production costs but also accelerates asphalt aging. Furthermore, the effect of single rubber powder modification on improving the high-temperature performance of asphalt is limited, making it difficult to meet the stringent high-temperature stability requirements of roads in heavy-load, high-temperature areas.

[0007] Compared with the prior art, the present invention adds silane coupling agent modified waste plastic particles and microwave activated waste tire rubber powder to asphalt mixture, and limits the mass ratio of modified waste plastic particles to activated waste tire rubber powder to 1:(1.5~2). This is because the inventors found that under this specific ratio, the surface-modified waste plastic particles (reinforcing phase) and microwave activated waste tire rubber powder (elastic phase) can form a stable interpenetrating network structure in asphalt. With the help of aggregates and mineral fillers to fully fill the gaps, the defects of high low-temperature brittleness and insufficient high-temperature performance of asphalt are synergistically solved, so that the mixture has excellent high-temperature stability and low-temperature crack resistance, and the performance reproducibility is significantly improved.

[0008] Furthermore, the aggregate includes any one of basalt, granite, and crushed gravel; the particle size of the crushed gravel is 1-3 mm.

[0009] Compared with the prior art, the present invention limits the aggregate to the components in the above-mentioned specific proportion, which is conducive to forming a dense and high-strength aggregate skeleton, effectively dispersing the traffic load borne by the road surface, reducing high-temperature rutting and fatigue damage, and improving the overall mechanical strength and durability of the mixture.

[0010] Furthermore, the mineral filler includes finely ground limestone ore powder, the fineness of which is 0.05-0.08 mm.

[0011] Compared with existing technologies, when the above-mentioned components are selected as mineral fillers, they can not only fully fill the gaps between aggregates and reduce the porosity, but also enhance the adhesion of asphalt mortar and significantly improve the problem of decreased adhesion between asphalt and aggregates.

[0012] Secondly, the present invention provides the application of the above-mentioned asphalt mixture in the preparation of modified asphalt; the modified asphalt has strong high-temperature stability and low-temperature crack resistance, and excellent durability.

[0013] Compared with existing technologies, this invention applies the asphalt mixture to the preparation of modified asphalt, which solves the performance shortcomings of traditional modified asphalt. Modified asphalt can be adapted to different climates and traffic conditions, thereby extending the service life of asphalt pavement and reducing maintenance costs.

[0014] Thirdly, the present invention provides a method for preparing modified asphalt, which is prepared using the above-mentioned asphalt mixture, comprising the following processes: Prepare modified waste plastic granules and activated waste tire rubber powder, and weigh each component according to the proportion of the asphalt mixture as described in any one of claims 1-3; The modified waste plastic particles are mixed with the base asphalt at 160-170℃. After 15-25 minutes, the temperature is lowered to 150-160℃, and the activated waste tire rubber powder is added and mixed. The swelling reaction is carried out for 40-60 minutes to obtain the composite modified asphalt. The aggregate and the mineral filler are mixed and heated to 185-195°C, then added to the composite modified asphalt. The mixture is stirred at 170-180°C for 45-90 seconds and discharged to obtain an asphalt mixture.

[0015] Compared with existing technologies, this invention mixes modified waste plastic particles and activated waste tire rubber powder at 160-170℃ for 15-25 minutes, cools to 150-160℃ for swelling reaction for 40-60 minutes, and then mixes with aggregates and mineral fillers at 185-195℃ at 170-180℃ for 45-90 seconds. This is because the inventors found that existing composite modification processes have problems such as disordered addition order and improper temperature control, resulting in degradation or uneven dispersion of solid waste components. This process first uses high temperature to fully disperse the modified waste plastic, and then cools down to allow the activated rubber powder to swell gently, avoiding high-temperature degradation of the rubber powder. The subsequent high-temperature mixing of aggregates and fillers ensures full integration with the composite modified asphalt. The entire process adapts to the physicochemical properties of each component, maximizes the synergistic modification effect, and ensures the stability of the modified asphalt performance.

[0016] Furthermore, the preparation of modified waste plastic pellets includes the following processes: Waste polyethylene is crushed and dried to obtain waste polyethylene granules. The waste polyethylene coarse particles are extruded into a molten viscous flow state, injected with the silane coupling agent, cooled, and then pelletized to obtain pre-modified particles; The preliminarily modified granules are kept at 100-110℃ for 1-2 hours and then naturally cooled to room temperature to obtain the target modified waste plastic granules.

[0017] Compared with the prior art, the present invention modifies waste plastics using the above method, which significantly improves the surface polarity and interfacial bonding ability of waste plastic particles, avoids their agglomeration in asphalt, and lays the foundation for synergistic effect with waste tire rubber powder.

[0018] Furthermore, in the steps of crushing and drying waste polyethylene, the particle size after crushing is 5-10 mm, and the moisture content after drying is ≤5%; the modifier includes KH550; and the particle size of the preliminary modified particles is 2-4 mm.

[0019] Furthermore, the preparation of the activated waste tire rubber powder includes the following process: Waste tires are crushed, impurities removed, and dried to obtain waste tire rubber powder; The waste tire rubber powder is activated under microwave conditions of 300-500W and 80-120℃ for 3-8 minutes, and then cooled to room temperature by introducing inert gas to obtain the target activated waste tire rubber powder.

[0020] Furthermore, in the steps of crushing, removing impurities, and drying the waste tires, the fineness of the crushed material is 30-40 mesh; the drying is carried out at 70-80℃ and a vacuum of -0.08MPa for 1.5-2 hours; in the step of activating the waste tire rubber powder under microwave conditions of 300-500W and 80-120℃, the microwave radiation is paused for 10 seconds every 30 seconds.

[0021] Compared with existing technologies, microwave activation causes the polar molecules inside the rubber powder to vibrate through internal heating, breaking the dense cross-linking bonds on the surface and generating a large number of active sites. The mild temperature of 80-120℃ and the activation time of 3-8 minutes prevent the degradation of the rubber powder. Inert gas cooling can prevent secondary oxidation of active sites, significantly improving the swelling and dispersibility of rubber powder and asphalt, and reducing the energy consumption of the activation process.

[0022] Furthermore, in the step of mixing the modified waste plastic particles with the base asphalt at 160-170℃, high-speed shearing is performed at a shearing speed of 5000-8000 rpm; in the step of adding the activated waste tire rubber powder, stirring is performed at a stirring speed of 300-500 rpm; and in the step of mixing at 170-180℃, stirring is performed at a stirring speed of 300-500 rpm.

[0023] Compared with existing technologies, this invention limits the step of mixing modified waste plastic particles with activated waste tire rubber powder to high-speed shearing at 5000-8000 rpm, and the steps of adding activated waste tire rubber powder and mixing the mixture to low-speed stirring at 300-500 rpm. This is because the inventors found that improper shearing or stirring speeds in existing processes lead to either insufficient dispersion or damage to the structure of solid waste components. High-speed shearing at 5000-8000 rpm can fully break down the modified waste plastic particles and evenly disperse them in the asphalt, while low-speed stirring at 300-500 rpm can ensure that the activated rubber powder is fully swollen and does not degrade. Low-speed stirring during mixture mixing allows the aggregates, fillers and composite modified asphalt to blend gently, avoiding excessive shearing that damages the already formed interpenetrating network structure and maximizing the synergistic effect of each component. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 A high-toughness asphalt mixture modified from waste plastics and rubber comprises the following components by weight fraction: The composition includes 80 parts of base asphalt, 2 parts of modified waste plastic granules, 4 parts of activated waste tire rubber powder, 100 parts of aggregate, and 30 parts of mineral filler. Among these, the modified waste plastic granules are waste polyethylene treated with a surface silane coupling agent; the activated waste tire rubber powder is waste tire rubber powder that has been microwave activated; the aggregate is basalt; and the mineral filler includes finely ground limestone ore powder with a fineness of 0.05-0.08 mm.

[0026] The process of preparing modified asphalt from the above mixture includes the following steps: S1. Preparation of modified waste plastic granules Waste polyethylene is crushed to a particle size of 5-10 mm and dried to a moisture content of 2.6% to obtain waste polyethylene granules. The waste polyethylene coarse particles are fed into a twin-screw extruder, and the temperatures of each section of the extruder are set as follows: feeding section 140℃, melting section 160℃, homogenization section 170℃, and die head 165℃. The screw speed is 200 rpm, and the extrusion is carried out to a molten viscous flow state. Silane coupling agent is injected, and the extrusion is carried out through the die orifice of the extruder head. The particles are cooled to 25℃ in a water cooling tank and then cut into uniform particles with a particle size of 2-4 mm by a pelletizer to obtain preliminary modified particles. The pre-modified granules were kept at 100℃ for 1 hour and then naturally cooled to room temperature to obtain the target modified waste plastic granules.

[0027] S2. Preparation of activated waste tire rubber powder Waste tires are crushed to 30-40 mesh, impurities are removed, and they are dried at 70℃ and -0.08MPa for 1.5 hours to obtain waste tire rubber powder. The waste tire rubber powder was activated for 3 minutes under microwave conditions of 300W and 80℃, with microwave radiation pausing for 10 seconds every 30 seconds; then inert gas was introduced to cool it to room temperature to obtain the target activated waste tire rubber powder.

[0028] S3. At 160℃, modified waste plastic particles are mixed with base asphalt. After high-speed shearing at 5000 for 15 minutes, the temperature is reduced to 150℃. Activated waste tire rubber powder is added and stirred at 300 rpm. The mixture is then allowed to swell for 40 minutes to obtain composite modified asphalt. S4. Mix the aggregates and mineral fillers and heat them to 185°C. Add the mixture to the composite modified asphalt and mix at 300 rpm for 45 seconds at 170°C. Discharge the mixture to obtain the asphalt mixture.

[0029] Example 2 A high-toughness asphalt mixture modified from waste plastics and rubber comprises the following components by weight fraction: The composition includes 150 parts of base asphalt, 8 parts of modified waste plastic granules, 12 parts of activated waste tire rubber powder, 150 parts of aggregate, and 40 parts of mineral filler. Among them, the modified waste plastic granules are waste polyethylene treated with a surface silane coupling agent; the activated waste tire rubber powder is waste tire rubber powder after microwave activation treatment; the aggregate is granite; and the mineral filler includes finely ground limestone ore powder with a fineness of 0.05-0.08 mm.

[0030] The process of preparing modified asphalt from the above mixture includes the following steps: S1. Preparation of modified waste plastic granules Waste polyethylene is crushed to a particle size of 5-10 mm and dried to a moisture content of 3.5% to obtain waste polyethylene granules. The waste polyethylene coarse particles are fed into a twin-screw extruder, and the temperatures of each section of the extruder are set as follows: feeding section 150℃, melting section 170℃, homogenization section 180℃, and die head 175℃. The screw speed is 250 rpm, and the extrusion is carried out to a molten viscous flow state. Silane coupling agent is injected, and the extrusion is carried out through the die orifice of the extruder head. The particles are cooled to 30℃ in a water cooling tank and then cut into uniform particles with a particle size of 2-4 mm by a pelletizer to obtain preliminary modified particles. The pre-modified granules were kept at 110℃ for 2 hours and then naturally cooled to room temperature to obtain the target modified waste plastic granules.

[0031] S2. Preparation of activated waste tire rubber powder Waste tires were crushed to 40 mesh to remove impurities and dried at 80℃ and -0.08MPa for 2 hours to obtain waste tire rubber powder. The waste tire rubber powder was activated under microwave conditions of 500W and 120℃ for 8 minutes, with microwave radiation for 30 seconds followed by a 10-second pause; then an inert gas was introduced to cool it to room temperature to obtain the target activated waste tire rubber powder.

[0032] S3. At 170℃, the modified waste plastic particles are mixed with the base asphalt. After high-speed shearing at 8000rpm for 25min, the temperature is reduced to 160℃. Activated waste tire rubber powder is added and stirred at 500rpm. The mixture is then allowed to swell for 60min to obtain the composite modified asphalt. S4. Mix the aggregates and mineral fillers and heat them to 195°C. Add the mixture to the composite modified asphalt and mix at 180°C and 500 rpm for 90 seconds. Discharge the mixture to obtain the asphalt mixture.

[0033] Example 3 A high-toughness asphalt mixture modified from waste plastics and rubber comprises the following components by weight fraction: The composition includes 100 parts of base asphalt, 6 parts of modified waste plastic granules, 10 parts of activated waste tire rubber powder, 120 parts of aggregate, and 35 parts of mineral filler. Among these, the modified waste plastic granules are waste polyethylene treated with a surface silane coupling agent; the activated waste tire rubber powder is waste tire rubber powder after microwave activation treatment; the aggregate is crushed gravel with a particle size of 1-3 mm; and the mineral filler includes finely ground limestone ore powder with a fineness of 0.05-0.08 mm.

[0034] The process of preparing modified asphalt from the above mixture includes the following steps: S1. Preparation of modified waste plastic granules Waste polyethylene is crushed to a particle size of 5-10 mm and dried to a moisture content of 1.9% to obtain waste polyethylene granules. The waste polyethylene coarse particles are fed into a twin-screw extruder, and the temperatures of each section of the extruder are set as follows: feeding section 145℃, melting section 165℃, homogenization section 175℃, and die head 170℃. The screw speed is 220 rpm, and the extrusion is carried out to a molten viscous flow state. Silane coupling agent is injected, and the extrusion is carried out through the die orifice of the extruder head. The particles are cooled to 28℃ in a water cooling tank and then cut into uniform particles with a particle size of 2-4 mm by a pelletizer to obtain preliminary modified particles. The pre-modified granules were kept at 105℃ for 1.5 hours and then naturally cooled to room temperature to obtain the target modified waste plastic granules.

[0035] S2. Preparation of activated waste tire rubber powder Waste tires were crushed to 30-40 mesh, impurities were removed, and the waste tires were dried at 75℃ and -0.08MPa for 1.8 hours to obtain waste tire rubber powder. The waste tire rubber powder was activated under microwave conditions of 400W and 100℃ for 5 minutes, with microwave radiation for 30 seconds followed by a 10-second pause; then an inert gas was introduced to cool it to room temperature to obtain the target activated waste tire rubber powder.

[0036] S3. At 165℃, the modified waste plastic particles are mixed with the base asphalt. After high-speed shearing at 6500rpm for 20min, the temperature is lowered to 155℃, activated waste tire rubber powder is added and stirred at 400rpm. The mixture is then allowed to swell for 50min to obtain the composite modified asphalt. S4. Mix the aggregates and mineral fillers and heat them to 190°C. Add the mixture to the composite modified asphalt and mix at 175°C and 400 rpm for 60 seconds. Discharge the mixture to obtain the asphalt mixture.

[0037] Comparative Example 1 In Comparative Example 1, the only difference from Example 3 is that the modified waste plastic particles were replaced with an equal amount of activated waste tire rubber powder.

[0038] Comparative Example 2 In Comparative Example 2, the only difference from Example 3 is that the activated waste tire rubber powder was replaced with an equal amount of modified waste plastic particles.

[0039] Comparative Example 3 In Comparative Example 3, the only difference from Example 3 is that the modified waste plastic particles are replaced with an equal amount of unmodified waste plastic particles, and the waste plastic is directly crushed.

[0040] Comparative Example 4 In Comparative Example 4, the only difference from Example 3 was that the activated waste tire rubber powder was replaced with an equal amount of unactivated waste tire rubber powder.

[0041] Comparative Example 5 In Comparative Example 5, the only difference from Example 3 was the change in the ratio of modified waste plastic particles to activated waste tire rubber powder, which increased the weight of modified waste plastic particles to 10 parts and decreased the weight of activated waste tire rubber powder to 6 parts.

[0042] Comparative Example 6 In Comparative Example 6, the only difference from Example 3 is that in S3, the base asphalt and activated waste tire rubber powder were first stirred and mixed at 155°C and 400 rpm for 50 min to swell and react. Then, modified waste plastic particles were added, and the mixture was sheared at 165°C and 6500 rpm for 20 min to obtain composite modified asphalt.

[0043] Performance testing The flexural stiffness (MPa) of the asphalt mixtures prepared in the above examples and comparative examples was tested according to T0739-2011 "Four-point Bending Fatigue Life Test of Asphalt Mixtures" in JTG E20-2011 "Interpretation Manual of Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The greater the flexural stiffness, the stronger the fatigue resistance of the road.

[0044] According to T0719-2011 "Rutting Test of Asphalt Mixtures" in JTG E20-2011 "Interpretation Manual of Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the dynamic stability (cycles / mm) of the asphalt mixtures prepared in the above examples and comparative examples was tested; the greater the dynamic stability, the higher the high temperature stability of the road.

[0045] According to T0729-2000 "Freeze-thaw splitting test of asphalt mixtures" in JTG E20-2011 "Interpretation Manual of Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the freeze-thaw splitting test strength ratio (%) of the asphalt mixtures prepared in the above examples and comparative examples was tested; the higher the freeze-thaw splitting test strength ratio, the higher the water stability of the road.

[0046] According to T0715-2011 "Bending Test of Asphalt Mixtures" in JTG E20-2011 "Interpretation Manual of Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the flexural stiffness modulus (MPa) of the asphalt mixtures prepared in the above examples and comparative examples was tested; the larger the flexural stiffness modulus, the better the low-temperature crack resistance of the road.

[0047] According to T0756-2011 "Rutting Deformation Test of Slurry Mixture" in JTG E20-2011 "Interpretation Manual of Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the deformation rate per unit width and the rutting depth rate per unit thickness of the micro-surfaced samples of the asphalt mixtures prepared in the above examples and comparative examples were tested; the smaller the deformation rate and rutting depth rate, the better the road's rutting resistance.

[0048] The modified asphalts of Examples 1 to 3 and Comparative Examples 1 to 6 were tested according to the above testing methods. The results are shown in Table 1.

[0049] Table 1. Test results of each group of modified asphalt

[0050] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-toughness asphalt mixture based on waste plastic and rubber composite modification, characterized in that, The asphalt mixture comprises the following components by weight fraction: The composition consists of 80-150 parts base asphalt, 2-8 parts modified waste plastic granules, 4-12 parts activated waste tire rubber powder, 100-150 parts aggregate, and 30-40 parts mineral filler. The modified waste plastic particles are waste polyethylene treated with a surface silane coupling agent. The activated waste tire rubber powder is waste tire rubber powder that has undergone microwave activation treatment. The mass ratio of the modified waste plastic particles to the activated waste tire rubber powder is 1:(1.5~2).

2. The high-toughness asphalt mixture based on waste plastic and rubber composite modification according to claim 1, characterized in that, The aggregate includes any one of basalt, granite, and crushed gravel; and / or, The particle size of the crushed gravel is 1-3 mm.

3. The high-toughness asphalt mixture based on waste plastic and rubber composite modification according to claim 1, characterized in that, The mineral filler includes finely ground limestone powder, the fineness of which is 0.05-0.08 mm.

4. The application of the asphalt mixture according to any one of claims 1-3 in the preparation of modified asphalt; the modified asphalt has strong high-temperature stability and low-temperature crack resistance, and excellent durability.

5. A method for preparing modified asphalt, characterized in that, The preparation of the asphalt mixture according to any one of claims 1-3 includes the following process: Prepare modified waste plastic granules and activated waste tire rubber powder, and weigh each component according to the proportion of the asphalt mixture as described in any one of claims 1-3; The modified waste plastic particles are mixed with the base asphalt at 160-170℃. After 15-25 minutes, the temperature is lowered to 150-160℃, and the activated waste tire rubber powder is added and mixed. The swelling reaction is carried out for 40-60 minutes to obtain the composite modified asphalt. The aggregate and the mineral filler are mixed and heated to 185-195°C, then added to the composite modified asphalt. The mixture is stirred at 170-180°C for 45-90 seconds and discharged to obtain an asphalt mixture.

6. The method for preparing modified asphalt according to claim 5, characterized in that, The preparation of modified waste plastic pellets includes the following processes: Waste polyethylene is crushed and dried to obtain waste polyethylene granules. The waste polyethylene coarse particles are extruded into a molten viscous flow state, injected with the silane coupling agent, cooled, and then pelletized to obtain pre-modified particles; The preliminarily modified granules are kept at 100-110℃ for 1-2 hours and then naturally cooled to room temperature to obtain the target modified waste plastic granules.

7. The method for preparing modified asphalt according to claim 6, characterized in that, In the steps of crushing and drying waste polyethylene, the particle size after crushing is 5-10 mm, and the moisture content after drying is ≤5%; and / or, The modifier includes KH550; and / or, The particle size of the pre-modified particles is 2-4 mm.

8. The method for preparing modified asphalt according to claim 5, characterized in that, The preparation of the activated waste tire rubber powder includes the following process: Waste tires are crushed, impurities removed, and dried to obtain waste tire rubber powder; The waste tire rubber powder is activated under microwave conditions of 300-500W and 80-120℃ for 3-8 minutes, and then cooled to room temperature by introducing inert gas to obtain the target activated waste tire rubber powder.

9. The method for preparing modified asphalt according to claim 8, characterized in that, In the steps of crushing, removing impurities, and drying the waste tires, the fineness of the crushed material is 30-40 mesh; and / or, The drying process is performed at 70-80℃ and a vacuum of -0.08MPa for 1.5-2 hours; and / or, In the step of activating the waste tire rubber powder under microwave conditions of 300-500W and 80-120℃, the microwave is irradiated for 30 seconds and then paused for 10 seconds.

10. A method for preparing modified asphalt according to any one of claims 5-9, characterized in that, In the step of mixing the modified waste plastic particles with the activated waste tire rubber powder at 160-170℃, high-speed shearing is performed at a shearing speed of 5000-8000 rpm; and / or, The step of adding the activated waste tire rubber powder is carried out at a stirring speed of 300-500 rpm; and / or, The mixing step at 170-180℃ is carried out at a stirring speed of 300-500 rpm.

Images