A high-content bio-oil activated rubber powder modified asphalt and its preparation method and production system

Abstract

The present invention provides a high-dosage bio-oil-activated rubber powder-modified asphalt, as well as a preparation method and production system thereof, relating to the technical field of asphalt material preparation. The method comprises: stirring rubber powder and bio-oil at 110±5°C and a negative pressure of -0.08 to -0.095 MPa for 45 to 60 minutes; switching to nitrogen pressure to 0.3 to 0.5 MPa and stirring for 20 to 30 minutes to obtain the bio-oil-activated rubber powder; adding the bio-oil-activated rubber powder to base asphalt, controlling the temperature at 160±5°C and the speed at 2500 to 5500 rpm; and shear mixing for 20 to 60 minutes to obtain the product. The rubber powder dosage is 20 to 35% and the bio-oil dosage is 10 to 15% based on the base asphalt. The present invention achieves the penetration and storage of bio-oil within the rubber powder through a high-temperature negative pressure-nitrogen pressurization collaborative pretreatment process, forming an in-situ reservoir effect to dynamically compensate for the loss of lightweight components during aging, giving the material self-repair and regeneration capabilities and long-term anti-aging properties, improving material compatibility and high- and low-temperature performance. It is particularly suitable for high-content rubber powder-modified asphalt systems, with a simple process and low energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt material preparation for road engineering, and in particular to a high-content bio-oil activated rubber powder modified asphalt and a preparation method and a production system thereof. Background Art

[0002] In highway construction and maintenance, asphalt is a key pavement material, and its performance has a direct impact on road service life and driving safety. To improve asphalt performance, rubber powder is often used for modification to produce rubber-modified asphalt. Rubber-modified asphalt exhibits excellent high-temperature stability, low-temperature flexibility, aging resistance, fatigue resistance, and water damage resistance, making it a preferred environmentally friendly pavement material. However, during the traditional preparation process, rubber powder particles easily absorb lightweight components in asphalt, resulting in deterioration of asphalt performance, decreased stability, increased viscosity, and poor workability. Furthermore, the current processing temperature of rubber-modified asphalt is typically maintained at a relatively high temperature of 180-200°C, which consumes a lot of energy and is prone to segregation, seriously affecting the storage stability and performance of rubber-modified asphalt.

[0003] To address these issues, some existing approaches propose using bio-oil to modify crumb rubber asphalt to further optimize its performance. For example, Chinese patent document CN118931213A discloses an anti-aging bio-based rubber asphalt material, its preparation method, and its application. This method involves mixing crumb rubber and bio-oil in a mass ratio of 1:1 (0.5-1.5), heating and stirring, and producing a substance A. Substance A is then swelled at room temperature for 6-18 hours to produce a bio-based expanded rubber. This expansion is then carried out under microwaves at a power of 300W-500W, a frequency of 2000MHz-3000MHz, and a time of 2-8 minutes to produce a bio-based modified rubber. Finally, the bio-based modified rubber is added to a base asphalt at a ratio of 10%-20%, and the mixture is stirred under heating to produce a bio-based rubber asphalt material. This method significantly improves the asphalt's anti-aging properties. This method primarily utilizes high-frequency microwave vibration to induce chemical depolymerization of the rubber's molecular chains, causing the crumb rubber to physically expand at high temperatures, forming a porous structure. Microwaves essentially trigger material pyrolysis due to energy input, leading to the destruction of the rubber crosslinking network and the sacrifice of rubber elasticity to enhance bio-oil adsorption. Chinese patent document CN118146645A discloses a method for preparing modified asphalt, comprising: S1: mixing petroleum asphalt and rubber powder and subjecting it to high-speed shearing to produce rubber asphalt; S2: mixing the rubber asphalt with bio-oil at 120-150°C and subjecting it to high-speed shearing to produce modified asphalt. The modified asphalt comprises 15-18% rubber powder and 5-10% bio-oil by weight. This method utilizes a "rubber-modified asphalt first, then bio-oil shearing" process. Its core mechanism relies on bio-oil as an admixture to directly improve the compatibility of rubber asphalt. However, the bio-oil exists only as a physically dispersed phase at the asphalt-rubber powder interface. Its modification efficiency stems from competitive adsorption of lighter components of the asphalt and cannot penetrate the rubber powder crosslinking network. Consequently, its modification effect is limited to interfacial lubrication, and further improvement is needed.

[0004] In addition, the rubber powder content in the above scheme is controlled below 20%. This is because high rubber powder content in traditional technology easily leads to rubber powder agglomeration, a sharp increase in asphalt viscosity and deterioration of low-temperature performance, and is not suitable for high-content rubber powder modified asphalt systems.

[0005] Therefore, it is urgent to develop a rubber-modified asphalt and a preparation method that can improve the modification effect of rubber-modified asphalt, especially improve the modification effect of high-content rubber-modified asphalt, and has a simple process and low energy consumption. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-content bio-oil-activated rubber powder-modified asphalt, as well as its preparation method and production system. This invention aims to address the shortcomings of the existing technology by first producing bio-oil-activated rubber powder and then producing bio-oil-activated rubber powder-modified asphalt using a high-temperature negative pressure-nitrogen pressurization synergistic pretreatment process. By optimizing the production process, the compatibility between the rubber powder and asphalt in the rubber powder-modified asphalt can be improved, and stratification and segregation can be reduced. Specifically, the high- and low-temperature performance of high-content rubber powder-modified asphalt can be enhanced, providing key technical support for the resource utilization of high-proportion waste rubber powder, while also simplifying the process and reducing production energy consumption.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing asphalt modified with high bio-oil content activated rubber powder, comprising the following steps:

[0009] S1. Stirring and mixing the rubber powder and bio-oil at 110±5°C and a negative pressure of -0.08 to -0.095 MPa for 45 to 60 minutes to allow the bio-oil to initially penetrate the rubber powder. Then, switching to nitrogen pressure at 0.3 to 0.5 MPa and stirring for 20 to 30 minutes to force the bio-oil to fill the pores of the rubber powder, thereby obtaining bio-oil-activated rubber powder.

[0010] S2. Add the bio-oil activated rubber powder of S1 to the hot matrix asphalt, control the temperature at 160±5°C, and control the shear speed at 2500-5500 rpm; shear and mix for 20-60 minutes to obtain the bio-oil activated rubber powder modified asphalt;

[0011] Calculated based on the mass of base asphalt, the amount of rubber powder added is 20~35% of the base asphalt; the amount of bio-oil added is 10%~15% of the base asphalt.

[0012] Furthermore, in order to ensure that the rubber powder and bio-oil are mixed evenly, the process of step S1 is carried out in a rubber powder pretreatment tank. The rubber powder pretreatment tank is provided with a stirring device, which includes a rotary drive and rotary blades. The rotary blades are arranged in the tank body. The rotary blades adopt an upper, middle and lower three-layer combined blade configuration. When working, the rotary drive controls the rotation speed of the three layers of blades respectively. The rotation speed of the upper blades is 60-90 rpm, which is used to generate strong shear force to break up rubber powder agglomerates; the rotation speed of the middle blades is 30-60 rpm, which is used to promote radial diffusion; the rotation speed of the lower blades is 15-30 rpm, which is used to enhance axial circulation and scrape the wall; at the same time, the rotary drive also controls the rotating blades as a whole to perform the following cyclic motion: forward rotation for 5 minutes, pause for 10 seconds, and then reverse rotation for 3 minutes to eliminate centrifugal stratification.

[0013] Furthermore, the nitrogen pressure in S1 is gradually increased at a rate of 0.03-0.07 MPa / min to a preset pressure.

[0014] Furthermore, the bio-oil in step S1 is a renewable plant-based pyrolysis product rich in light components, which is prepared from agricultural and forestry wastes rich in cellulose, hemicellulose and lignin, and the agricultural and forestry wastes include corn straw, rice husks, wheat straw, sawdust, etc.

[0015] Furthermore, the rubber powder in step S1 is a particle obtained by mechanically crushing waste tires, or a particle obtained by grinding waste rubber conveyor belts or waste rubber seals at room temperature, and the particle size range of the particle is controlled to be 0.3mm~0.6mm.

[0016] In a second aspect, the present invention further provides a production system for high-volume bio-oil-activated rubber powder-modified asphalt capable of implementing the above-mentioned preparation method, comprising a rubber powder pretreatment tank, a rubber powder-modified asphalt high-speed shear tank, and a rubber powder-modified asphalt storage tank connected in sequence; the rubber powder pretreatment tank and the rubber powder-modified asphalt high-speed shear tank are connected via a bio-oil pretreatment rubber powder conveyor, and the rubber powder-modified asphalt high-speed shear tank and the rubber powder-modified asphalt storage tank are connected via a rubber powder-modified asphalt conveyor;

[0017] It also includes a rubber powder conveying assembly, a bio-oil pumping assembly, a nitrogen pressurizing assembly, and a vacuum pump assembly connected to the rubber powder pretreatment tank; the rubber powder conveying assembly is used to quantitatively convey rubber powder to the rubber powder pretreatment tank, the bio-oil pumping assembly is used to quantitatively pump bio-oil into the rubber powder pretreatment tank, the nitrogen pressurizing assembly is used to pressurize the rubber powder pretreatment tank with nitrogen, and the vacuum pump assembly is used to achieve negative pressure conditions in the rubber powder pretreatment tank;

[0018] Also included is a hot asphalt delivery assembly for delivering hot base asphalt to the crumb rubber modified asphalt high-speed shear tank;

[0019] The rubber powder pretreatment tank is provided with a temperature control device and a stirring device; the rubber powder modified asphalt high-speed shearing tank is also provided with a temperature control device and a stirring device; the rubber powder modified asphalt storage tank is also provided with a stirring device.

[0020] Furthermore, the temperature control device of the rubber powder pretreatment tank includes a jacketed thermal oil circulation heating device and a first PID temperature controller, which is used to control the temperature in the rubber powder pretreatment tank at 110±5°C; its stirring device includes a rotary driver and a rotary blade, and the rotary driver can drive the rotary blade to rotate the material in the stirring tank.

[0021] Furthermore, the rotating blades of the rubber powder pretreatment tank are arranged in the tank body, adopting a three-layer combined blade configuration of upper, middle and lower layers. The upper blades are folding paddle blades, the middle blades are spiral belt blades, and the lower blades are anchor blades. The gap between the outer edge of the anchor blade and the tank wall is ≤5mm, and polytetrafluoroethylene (PTFE) or wear-resistant rubber scrapers are provided; the rotary driver is arranged at the top of the rubber powder pretreatment tank, and is used to control the speed, rotation time and rotation direction of the rotating blades.

[0022] Furthermore, the temperature control device of the rubber powder modified asphalt high-speed shear tank includes a jacketed thermal oil circulation heating device and a second PID temperature controller, which is used to control the temperature in the rubber powder modified asphalt high-speed shear tank at 160±5°C; its stirring device includes a high-speed shear controller and a rotating high-speed shear device, and the high-speed shear controller can drive the rotating high-speed shear device to rotate the material in the stirring tank and control the shear speed and shear time of the rotating high-speed shear device.

[0023] Furthermore, the stirring device of the rubber powder modified asphalt storage tank includes a stirring blade and a stirring driver. The stirring blade is arranged in the rubber powder modified asphalt storage tank, and the stirring driver is arranged on the top of the rubber powder modified asphalt storage tank. The stirring driver is used to drive the stirring blade to rotate the material in the stirring tank and control the stirring speed, rotation time and rotation direction of the stirring blade.

[0024] The rubber powder conveying assembly further includes a rubber powder storage box, a rubber powder conveying pipe, a fan, a spiral metering scale, and a first valve. The rubber powder conveying pipe connects the rubber powder storage box and the rubber powder pretreatment tank. The first valve, fan, and spiral metering scale are sequentially installed on the rubber powder conveying pipe. The fan prevents rubber powder from agglomerating and removes impurities (dust) on the rubber powder surface. The spiral metering scale is used to control the amount of rubber powder used.

[0025] The bio-oil pumping assembly further includes a bio-oil storage tank, a bio-oil delivery pipe, a metering pump, and a second valve. The bio-oil delivery pipe connects the bio-oil storage tank to the rubber powder pretreatment tank. The second valve and metering pump are sequentially installed on the bio-oil delivery pipe. The metering pump is used to quickly deliver the bio-oil to the rubber powder pretreatment tank and to control the amount of bio-oil used.

[0026] Furthermore, the nitrogen pressurization assembly includes a nitrogen tank, a nitrogen pressurization pipe, a third valve, a second pressure controller, and a pressure pump. The nitrogen pressurization pipe connects the nitrogen tank to the rubber powder pretreatment tank. The third valve, second pressure controller, and pressure pump are mounted on the nitrogen pressurization pipe. The pressure pump rapidly fills the rubber powder pretreatment tank with nitrogen and pressurizes it. The second pressure controller controls the pressure within the tank between 0.3 and 0.5 MPa (gauge pressure). A pump-suction nitrogen concentration detector is installed at the bottom of the nitrogen tank to monitor the nitrogen concentration within the tank.

[0027] Furthermore, the vacuum pump assembly includes a vacuum pump, a vacuum extraction pipeline, a fourth valve and a first pressure controller. The vacuum pump is connected to the bottom of the rubber powder pretreatment tank through the vacuum extraction pipeline. The fourth valve and the first pressure controller are arranged on the vacuum extraction pipeline. The first pressure controller is electrically connected to the vacuum pump and is used to control the pressure in the rubber powder pretreatment tank at -0.08~-0.095MPa (gauge pressure).

[0028] Furthermore, the hot asphalt conveying assembly includes a hot asphalt storage tank, a hot asphalt conveyor, and a fifth valve. The hot asphalt conveyor connects the hot asphalt storage tank and the rubber powder modified asphalt high-speed shear tank. The fifth valve is provided on the hot asphalt conveyor.

[0029] A weight detector is provided at the bottom of the hot asphalt storage box to control the mass of the hot asphalt added to the rubber-modified asphalt high-speed shear tank. A microwave heating device is installed in the hot asphalt storage box to control the temperature inside the hot asphalt storage box at 150±10℃.

[0030] Furthermore, the bio-oil pre-treated rubber powder conveyor, the hot asphalt conveyor, and the rubber powder modified asphalt conveyor adopt shaftless screw conveyors, and the number of them can be adjusted according to actual conditions.

[0031] In a third aspect, the present invention also provides a high-content bio-oil activated rubber powder modified asphalt prepared by the above preparation method or a high-content bio-oil activated rubber powder modified asphalt produced by the above production system.

[0032] The raw materials of the high-content bio-oil activated rubber powder modified asphalt include base asphalt, rubber powder with a mass percentage of 20-35% of the base asphalt, and bio-oil with a mass percentage of 10-15% of the base asphalt.

[0033] The present invention has the following beneficial effects:

[0034] The present invention provides a preparation method of high-content bio-oil-activated rubber powder modified asphalt. Through a high-temperature negative pressure-nitrogen pressurization collaborative pretreatment process, the directional penetration and storage of bio-oil inside the rubber powder are achieved, forming an in-situ reservoir effect to dynamically compensate for the loss of light components during aging, giving the material self-repair and regeneration capabilities and long-term anti-aging properties, and improving the material's compatibility and high and low temperature performance. The method is particularly suitable for high-content rubber powder modified asphalt systems.

[0035] The present invention first prepares a bio-oil activated rubber powder by a negative pressure-nitrogen pressurization coordinated physical penetration method: 1. In the negative pressure stage (-0.08~-0.095MPa): the gas stagnation in the pores is eliminated by a vacuum environment, a capillary pressure gradient is established, and the bio-oil is driven to achieve rapid spontaneous penetration of the surface micropores at 110±5℃; 2. In the nitrogen pressurization stage (0.3~0.5MPa): the bio-oil is driven by inert gas pressure to forcibly fill the deep pores of the rubber powder, and the dual effects are simultaneously achieved: (1) physical barrier: the nitrogen atmosphere effectively inhibits the thermal oxidation reaction of the rubber powder; (2) structural optimization: a dense oil film barrier is formed to prevent the rubber powder from excessively absorbing the light components of the asphalt during the subsequent asphalt modification process. The obtained bio-oil activated rubber powder is then added to the matrix asphalt to prepare a high-dosage bio-oil activated rubber powder modified asphalt.

[0036] The solution of the present invention can achieve the following through the regulation of the physical pressure gradient: (1) molecular structure preservation: avoiding the destruction of the rubber cross-linking network; (2) gradient swelling mechanism: the interaction between rubber powder and asphalt has an outer layer-inner core swelling gradient (outer layer swelling rate > inner core), which can establish an "in situ reservoir" (oil storage microcapsule) effect; (3) dynamic release characteristics: the light components of bio-oil are supplied in a "outer layer priority release - inner core continuous compensation" mode; (4) synergistic protection system: the dense oil film and dynamic release work together to effectively delay the loss of light components during the asphalt aging process.

[0037] Different from the contradictory phenomenon in traditional technology where high rubber powder content leads to improved high-temperature performance and deteriorated low-temperature performance, the present invention can achieve a positive correlation improvement in the high- and low-temperature performance of high-content rubber powder modified asphalt through the synergistic mechanism of the in-situ storage effect of bio-oil and nitrogen inert interface modification, providing key technical support for the resource utilization of high-proportion waste tire rubber powder.

[0038] The production system of the present invention connects high-temperature negative pressure, nitrogen pressurization and high-speed shearing units in series, and can realize the integrated production of rubber powder pretreatment and asphalt modification.

[0039] Compared with the existing technology, the present invention uses a stepped pressure control process to activate the rubber powder with bio-oil. Under specific temperature conditions, a negative pressure environment is first used to eliminate gas stagnation in the rubber powder pores, establishing a capillary pressure gradient to drive the initial penetration of bio-oil; then a nitrogen pressurization process is used to force the bio-oil to fill the deep pores of the rubber powder. This synergistic treatment mechanism creates an in-situ reservoir effect within the rubber powder, which can dynamically compensate for the loss of lightweight components in the asphalt system during production and application. At the same time, the nitrogen inert atmosphere effectively inhibits the oxidation of the rubber powder and optimizes the interfacial bonding performance. Subsequently, the rubber powder treated with bio-oil under negative pressure and nitrogen pressurization and the matrix asphalt are subjected to a mechanical-thermal synergistic high-speed shear process to construct a stable three-dimensional network structure, achieving uniform dispersion of the rubber powder in the asphalt matrix and suppressing segregation. By integrating key processes such as negative pressure penetration, nitrogen pressurization, high-speed shearing, and stirring and development in a modular production unit, the continuous operation of bio-oil pretreatment of rubber powder and asphalt modification is achieved, significantly reducing the system viscosity and production energy consumption while improving high-temperature stability and low-temperature ductility.

[0040] The present invention combines waste biomass resources with the recycling of waste rubber to construct a resource recycling system. While improving storage stability and construction workability, it provides environmentally friendly high-performance asphalt materials for road engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention provides a schematic flow chart of the method for preparing bio-oil activated rubber powder modified asphalt.

[0042] Figure 2 This is a schematic structural diagram of a production system for bio-oil activated rubber powder modified asphalt provided in an embodiment of the present invention.

[0043] Figure 3 This is a process flow chart of a production system provided by an embodiment of the present invention.

[0044] Figure 4 This is a schematic structural diagram of the rotating blades of the rubber powder pretreatment tank provided in an embodiment of the present invention.

[0045] Description of the accompanying drawings: 1. Rubber powder pretreatment tank; 2. Rubber powder storage box; 3. Rubber powder delivery pipe; 4-1. First valve; 4-2. Second valve; 4-3. Third valve; 4-4. Fourth valve; 4-5. Fifth valve; 5. Fan; 6. Spiral metering scale; 7. Bio-oil storage box; 8. Bio-oil delivery pipe; 9. Metering pump; 10. Vacuum pump; 11-1. First pressure controller; 11-2. Second pressure controller; 12. Nitrogen tank; 13. Nitrogen pressure pipe; 14. Pressure pump; 15-1. First PID temperature controller; 15-2. Second PID temperature controller 16. Rotary drive; 17. Rotary blade; 17-1. Folding paddle blade; 17-2. Spiral belt blade; 17-3. Anchor blade; 18. Safety pressure relief valve; 19. Flow transmitter; 20. Bio-oil pretreatment rubber powder conveyor; 21. Hot asphalt storage tank; 22. Hot asphalt conveyor; 23. Rubber powder modified asphalt high-speed shear tank; 24. High-speed shear controller; 25. Rotary high-speed shear device; 26. Rubber powder modified asphalt conveyor; 27. Rubber powder modified asphalt storage tank; 28. Agitation drive; 29. Agitation blade; 30. Discharge port. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be further explained below with reference to the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] See also Figure 1 The present invention provides a method for preparing bio-oil activated rubber powder modified asphalt, comprising the following steps:

[0049] S1. Stir and mix the rubber powder and bio-oil at 110±5°C and a negative pressure of -0.08 to -0.095 MPa for 45 to 60 minutes to allow the bio-oil to initially penetrate the rubber powder. Then, switch to nitrogen pressure at 0.3 to 0.5 MPa and stir and mix for 20 to 30 minutes to force the bio-oil to fill the pores of the rubber powder, thereby obtaining bio-oil-activated rubber powder.

[0050] During the nitrogen pressurization stage, a gradient pressure increase method is adopted at a rate of 0.03~0.07MPa / min to gradually increase the pressure to the target pressure value. It is generally preferred to control the gradient pressure increase rate of nitrogen to 0.05MPa / min. This method can effectively avoid the bio-oil on the surface of the rubber powder being squeezed out due to pressure shock, while ensuring the filling efficiency of the rubber powder pores. If the pressurization speed is too fast, the oil film on the surface of the rubber powder will rupture; if the pressurization speed is too slow, the bio-oil will be enriched in local areas. The gradient pressure increase strategy provided by the present invention enables the bio-oil to be driven by nitrogen pressure to achieve step-by-step filling of the rubber powder pores, thereby avoiding the interface peeling phenomenon caused by sudden pressure changes.

[0051] In order to eliminate the centrifugal stratification phenomenon and ensure uniform mixing of rubber powder and bio-oil, the S1 process is designed to be carried out in a rubber powder pretreatment tank. The rubber powder pretreatment tank is equipped with a stirring device, which includes a rotary drive and rotary blades. The rotary blades are arranged in the tank body. The rotary blades adopt a three-layer combined blade configuration of upper, middle and lower layers. During operation, the rotary drive controls the rotation speed of the three layers of blades respectively. The rotation speed of the upper blades is 60-90 rpm, which is used to generate strong shear force to break up rubber powder agglomerates; the rotation speed of the middle blades is 30-60 rpm, which is used to promote radial diffusion; the rotation speed of the lower blades is 15-30 rpm, which is used to enhance axial circulation and scrape the wall; at the same time, the rotary drive also controls the rotating blades as a whole to perform the following cyclic motion: forward rotation for 5 minutes, pause for 10 seconds, and then reverse rotation for 3 minutes.

[0052] S2. Add the bio-oil activated rubber powder of S1 to the hot matrix asphalt, control the temperature at 160±5°C, and control the shear speed at 2500~5500rpm; shear and mix for 20~60min to obtain the bio-oil activated rubber powder modified asphalt.

[0053] During the preparation process, the amount of rubber powder is controlled to be 20~35% of the mass of the matrix asphalt; the amount of bio-oil is controlled to be 10%~15% of the mass of the matrix asphalt.

[0054] In a specific embodiment, the bio-oil in step S1 is a renewable plant-based pyrolysis product rich in light components, which is prepared from agricultural and forestry waste rich in cellulose, hemicellulose and lignin.

[0055] Typically, agricultural and forestry wastes include biomass feedstocks such as corn stalks, rice husks, wheat straw, and sawdust. The main chemical components of this type of bio-oil include esters (such as methyl heptanoate, methyl hexanoate, and methyl octanoate), acids (short-chain fatty acids such as acetic acid and palmitic acid; for example, rice husk bio-oil contains high levels of acetic acid and butyric acid), aldehydes (including short-chain aldehydes such as hexanal and valeraldehyde, which are typical products generated during the pyrolysis of cellulose and hemicellulose), ketones (such as 2-heptanone, acetone, and cyclopentanone, which are typically produced by the degradation of lignin and carbohydrates), and phenols (such as guaiacol, methoxyphenol, and eugenol, which are typically produced by the pyrolysis of lignin). Furans (such as 2-furfural, which is primarily derived from the dehydration of hemicellulose), aromatic hydrocarbons, and alkanes are also included. Its main light components include aldehydes and ketones (such as hexanal and acetone), small molecule esters (such as methyl heptanoate and ethyl acetate), monocyclic phenols (such as phenol and guaiacol), short-chain fatty acids (such as acetic acid and butyric acid), furans (such as furfural), and small molecule hydrocarbons (such as olefins and toluene). Light components generally refer to compounds with lower boiling points and smaller molecular weights, and primarily include: aldehydes and ketones (such as hexanal and acetone), small molecule esters (such as methyl heptanoate and ethyl acetate), monocyclic phenols (such as phenol and guaiacol), short-chain fatty acids (such as acetic acid and butyric acid), furans (such as furfural), and small molecule hydrocarbons (such as olefins and toluene). The light components in bio-oil can improve the rheological properties of asphalt through: 1) plasticization: small molecules penetrate the rubber powder particles, promoting swelling and dispersion; 2) antioxidant properties: phenolic compounds inhibit the formation of aging products (such as reducing carbonyl compounds); and 3) interfacial strengthening: esters enhance the affinity between asphalt and aggregate, improving resistance to water damage.

[0056] In a specific embodiment, the rubber powder in step S1 is particles obtained by mechanically crushing waste tires or particles obtained by grinding waste rubber products (such as conveyor belts and seals) at room temperature, and the particle size range is controlled to be 0.3 mm to 0.6 mm.

[0057] In the preparation method provided by the present invention, bio-activated rubber powder is first prepared and then used to modify base asphalt. During the preparation of the bio-oil-activated rubber powder, negative pressure is first applied to promote interaction between the rubber powder and bio-oil, ensuring that the bio-oil is fully absorbed by the rubber powder. Nitrogen pressure is then switched to promote the bio-oil's entry into the gaps within the rubber powder. Under the action of pressure, a tight "oil film" is formed on the surface of the rubber powder, forming an "interface layer." This promotes interaction between the pretreated rubber powder and hot asphalt, improving their compatibility. It also provides an oxygen-free environment for the bio-oil-pretreated rubber powder, further facilitating its absorption of the bio-oil and preventing spontaneous combustion due to uneven heating during the bio-oil pretreatment process. A rotating device is provided within the rubber powder pretreatment tank for stirring the rubber powder and bio-oil, ensuring uniform heating and more complete bio-oil absorption.

[0058] In the negative pressure stage (-0.08~-0.095MPa), the vacuum environment eliminates gas entrapment in the pores, creates a capillary pressure gradient, and drives the bio-oil to achieve rapid spontaneous penetration of surface micropores at 110±5℃. Then, in the nitrogen pressurization stage (0.3~0.5MPa), the inert gas pressure is used to drive the bio-oil to forcibly fill the deep pores of the rubber powder, simultaneously achieving dual effects: (1) physical barrier: the nitrogen atmosphere effectively inhibits the thermal oxidation reaction of the rubber powder; (2) structural optimization: a dense oil film barrier is formed to prevent the rubber powder from excessively absorbing the light components of the asphalt during the subsequent asphalt modification process. The obtained bio-oil is then used to activate the rubber powder and add it to the matrix asphalt to produce modified asphalt.

[0059] In order to realize the preparation method of the present invention, this embodiment provides a production system of bio-oil activated rubber powder modified asphalt, such as Figure 2 As shown, the production system includes a rubber powder pretreatment tank 1, a rubber powder modified asphalt high-speed shear tank 23 and a rubber powder modified asphalt storage tank 27 connected in sequence; the rubber powder pretreatment tank 1 and the rubber powder modified asphalt high-speed shear tank 23 are connected via a bio-oil pretreatment rubber powder conveyor 20, and a flow transmitter 19 is provided on the conveying pipelines of the two, and the rubber powder modified asphalt high-speed shear tank 23 and the rubber powder modified asphalt storage tank 27 are connected via a rubber powder modified asphalt conveyor 26.

[0060] It also includes a rubber powder conveying component, a bio-oil pumping component, a nitrogen pressurizing component, and a vacuum pump component connected to the rubber powder pretreatment tank; the rubber powder conveying component is used to quantitatively convey rubber powder to the rubber powder pretreatment tank, the bio-oil pumping component is used to quantitatively pump bio-oil to the rubber powder pretreatment tank, the nitrogen pressurizing component is used to nitrogen pressurize the rubber powder pretreatment tank, and the vacuum pump component is used to achieve negative pressure conditions in the rubber powder pretreatment tank; it also includes a hot asphalt conveying component, which is used to convey hot base asphalt to the rubber powder modified asphalt high-speed shear tank.

[0061] As a preferred embodiment, the rubber powder conveying assembly in this embodiment includes a rubber powder storage box 2, a rubber powder conveying pipe 3, a fan 5, a spiral weighing scale 6, and a first valve 4-1. The rubber powder conveying pipe 3 connects the rubber powder storage box 2 with the rubber powder pretreatment tank 1. The first valve 4-1, fan 5, and spiral weighing scale 6 are sequentially arranged on the rubber powder conveying pipe 5. The fan 5 is used to prevent rubber powder from agglomerating and remove impurities (such as dust) on the rubber powder surface. The spiral weighing scale 6 is used to control the amount of rubber powder used.

[0062] As a preferred embodiment, the bio-oil pumping assembly in this embodiment includes a bio-oil storage tank 7, a bio-oil delivery pipe 8, a metering pump 9, and a second valve 4-2. The bio-oil delivery pipe 8 connects the bio-oil storage tank 7 with the rubber pretreatment tank 1. The second valve 4-2 and metering pump 9 are sequentially installed on the bio-oil delivery pipe 8. The metering pump 9 is used to quickly ensure that the bio-oil enters the rubber pretreatment tank 1 and to control the amount of bio-oil used.

[0063] As a preferred embodiment, the nitrogen pressurizing assembly in this embodiment includes a nitrogen tank 12, a nitrogen pressurizing pipe 13, a third valve 4-3, a second pressure controller 11-2 and a pressure pump 14. The nitrogen pressurizing pipe 13 is used to connect the nitrogen tank 12 and the rubber powder pretreatment tank 1. The third valve 4-3, the second pressure controller 11-2 and the pressure pump 14 are arranged on the nitrogen pressurizing pipe 13; the pressure pump 14 is used to quickly fill the rubber powder pretreatment tank 1 with nitrogen and pressurize it. The second pressure controller 11-2 is used to control the nitrogen pressure in the rubber powder pretreatment tank 1 within a preset range (gauge pressure). A pump-suction nitrogen concentration detector for detecting the nitrogen concentration in the nitrogen tank is provided at the bottom of the nitrogen tank 12.

[0064] As a preferred embodiment, the vacuum pump assembly in this embodiment includes a vacuum pump 10, a vacuum extraction pipeline, a fourth valve 4-4 and a first pressure controller 11-1. The vacuum pump 10 is connected to the bottom of the rubber powder pretreatment tank 1 through the vacuum extraction pipeline. The fourth valve 4-4 and the first pressure controller 11-1 are arranged on the vacuum extraction pipeline. The first pressure controller 11-1 is electrically connected to the vacuum pump 10 and is used to control the pressure in the rubber powder pretreatment tank 1 within a preset range (gauge pressure).

[0065] As a preferred embodiment, the hot asphalt conveying assembly in this embodiment includes a hot asphalt storage tank 21, a hot asphalt conveyor 22, and a fifth valve 4-5. The hot asphalt conveyor 22 connects the hot asphalt storage tank 21 with the crumb rubber-modified asphalt high-speed shear tank 23. The fifth valve 4-5 is located on the hot asphalt conveyor 22. A weight detector (not shown) is installed at the bottom of the hot asphalt storage tank 22 to control the mass of the hot asphalt added to the crumb rubber-modified asphalt high-speed shear tank 23. The hot asphalt storage tank 22 is equipped with a microwave heating device (not shown) to control the temperature within the hot asphalt storage tank at 150±10°C.

[0066] The rubber powder pretreatment tank 1 in this embodiment is provided with a temperature control device and a stirring device; the rubber powder modified asphalt high-speed shear tank 23 is also provided with a temperature control device and a stirring device; and the rubber powder modified asphalt storage tank 27 is also provided with a stirring device.

[0067] Specifically, the temperature control device of the rubber powder pretreatment tank 1 includes a jacketed thermal oil circulation heating device of the tank body and a first PID temperature controller 15-1. The jacketed thermal oil circulation heating device is electrically connected to the first PID temperature controller 15-1 and is used to control the temperature in the rubber powder pretreatment tank at 110±5°C. Its stirring device includes a rotary driver 16 and a rotary blade 17. The rotary driver 16 can drive the rotary blade 17 to rotate and stir the material in the tank. The rotary driver 16 is set at the top of the rubber powder pretreatment tank 1 and is used to control the speed, rotation time and rotation direction of the rotary blade 17. As a preferred embodiment, Figure 4 As shown, the rotating blades of the rubber powder pretreatment tank 1 in this embodiment are arranged in the tank body, and adopt an upper, middle and lower three-layer combined blade configuration. The upper blades are folding paddle blades 17-1, preferably 45° folding paddle blades, the middle blades are spiral belt blades 17-2, and the lower blades are anchor blades 17-3. The outer edge of the anchor blade 17-3 has a gap of ≤5mm from the tank wall, and is inlaid with polytetrafluoroethylene (PTFE) or wear-resistant rubber scrapers.

[0068] Specifically, the temperature control device of the rubber-modified asphalt high-speed shear tank 23 includes a jacketed thermal oil circulation heater within the tank and a second PID temperature controller 15-2. The jacketed thermal oil circulation heater is electrically connected to the second PID temperature controller 15-2 and is used to control the temperature within the rubber-modified asphalt storage tank at 160±5°C. Its agitation mechanism includes a high-speed shear controller 24 and a rotating high-speed shear device 25. The high-speed shear controller 24 drives the rotating high-speed shear device 25 to rotate the material within the agitation tank and control the shearing speed and shearing time of the rotating high-speed shear device 25. The strong shear force of the rotating high-speed shear device 25 effectively breaks up agglomerates of rubber powder particles, uniformly dispersing them in the asphalt and avoiding uneven properties caused by localized aggregation. The mechanical energy generated by the rotating high-speed shear device 25 during the shearing process activates the rubber powder surface, promoting the physical and chemical crosslinking of the bio-oil and rubber powder, and improving the swelling and dispersion of the rubber powder in the asphalt. The micron- and even nanometer-scale shearing action generated by the high-speed shearing enhances the interfacial bonding between the bio-oil-pretreated rubber powder and the asphalt, further enhancing material compatibility.

[0069] Specifically, the stirring device of the rubber powder modified asphalt storage tank 27 includes a stirring driver 28 and a stirring blade 29. The stirring blade 29 is arranged in the rubber powder modified asphalt storage tank 27, and the stirring driver 28 is arranged on the top of the rubber powder modified asphalt storage tank 27. The stirring driver 28 is used to drive the stirring blade 29 to rotate the material in the stirring tank and control the stirring speed, rotation time and rotation direction of the stirring blade 29.

[0070] As a preferred embodiment, the bio-oil pretreated rubber powder conveyor 20, hot asphalt conveyor 22, and rubber powder modified asphalt conveyor 26 in this embodiment adopt existing shaftless screw conveyors that can realize material conveying functions, and their number is adjusted according to actual conditions.

[0071] Example 2

[0072] like Figure 3 As shown, this embodiment provides a process flow for producing the bio-oil activated rubber powder modified asphalt using the production system provided in Example 1. As a preferred embodiment, the process flow specifically includes the following steps:

[0073] 1. Rubber powder loading: Use the rubber powder storage box 2 to heat the rubber powder for 15 to 25 minutes, open the first valve 4-1, and start the fan 5 and the spiral metering scale 6 to work. The fan 5 is used to remove dust in the rubber powder. The spiral metering scale 6 accurately controls the quality of the rubber powder transported by the rubber powder conveying pipe 3 to the rubber powder pretreatment tank 1.

[0074] 2. Bio-oil loading: Use the bio-oil storage tank 7 to heat the bio-oil for 15-30 minutes, open the second valve 4-2, and start the metering pump 9. The metering pump 9 accurately controls the quality of the bio-oil delivered to the rubber powder pretreatment tank 1 through the bio-oil delivery pipe 8.

[0075] 3. Mixing Rubber Powder and Bio-Oil: After heating the rubber powder and bio-oil in rubber powder pretreatment tank 1 to 110±5°C, a rotary actuator 16 controls the speed of rotating blades 17 in different layers. The upper blades are set at 90 rpm (high speed) to generate strong shear force and break up rubber powder agglomerates; the middle blades are set at 60 rpm (medium speed) to promote radial diffusion; and the lower blades are set at 30 rpm (low speed) to enhance axial circulation and scrape the wall. Rotary actuator 16 controls rotating blades 17 in the following cycle: forward rotation for 5 minutes, pause for 10 seconds, and then reverse rotation for 3 minutes to eliminate centrifugal stratification and ensure uniform mixing of rubber powder and bio-oil.

[0076] 4. High Temperature and Negative Pressure: The temperature within the rubber powder pretreatment tank 1 is maintained at 110±5°C to prevent the bio-oil viscosity from increasing and affecting its penetration efficiency. In this embodiment, tire rubber powder is used, primarily composed of cross-linked vulcanized rubber. High temperatures can break down some sulfur bonds, promote molecular chain relaxation, increase porosity, and facilitate bio-oil penetration. The temperature does not exceed 120°C, which minimizes the volatilization of light components in the bio-oil (such as phenols and aldehydes).

[0077] Open vacuum pump 10 and fourth valve 4-4, and control the pressure in rubber powder pretreatment tank 1 to -0.09 MPa (gauge pressure) via first pressure controller 11-1 for 50 minutes. Initially, the pressure is slowly pumped at -0.05 MPa to prevent rapid shrinkage of the particle surface and pore blockage. After 10 minutes, the pressure is reduced to -0.09 MPa and maintained. High-temperature negative pressure promotes interaction between rubber powder and bio-oil, and it expels gas trapped in the rubber powder pores, eliminating capillary resistance and creating a pressure gradient that drives the bio-oil into the pores.

[0078] 5. Nitrogen Pressurization: The temperature within the rubber powder pretreatment tank 1 is maintained at 110±5°C. Pressurizing pump 14 and third valve 4-3 are opened to allow nitrogen from nitrogen tank 12 to rapidly fill the rubber powder pretreatment tank 1 through nitrogen pressurizing pipe 13. Second pressure controller 11-2 controls the pressure within tank 1 at 0.4 MPa (gauge) for a specified period of time. Initially, the pressure is increased to the target value at a rate of 0.05 MPa / min to prevent pressure shock from causing bio-oil extrusion from the particle surface. The negative pressure phase removes gas from the pores. The pressurization phase further utilizes the pressure differential to drive the bio-oil deeper into the rubber powder pores, optimizing its infiltration. Using nitrogen pressurization also prevents oxygen-induced bio-oil oxidation (such as fatty acid ester rancidity and phenol polymerization). Nitrogen also has a low molecular weight and a fast diffusion rate, facilitating uniform pressure transmission.

[0079] 6. Rubber Powder Discharge: After nitrogen pressurization is complete, open the safety relief valve 18 and slowly release the pressure (at a rate of <0.05 MPa / min) to prevent reverse seepage of bio-oil from the pores of the rubber powder due to rapid pressure drop. A small amount of nitrogen dissolved in the bio-oil is released during pressure relief, generating microbubble disturbances that break down local interfacial tension barriers (similar to the "air surge effect") and improve permeation uniformity. After pressure relief is complete, open the flow transmitter 19 to control the mass of the bio-oil pretreated rubber powder delivered to the rubber powder-modified asphalt high-speed shear tank 23.

[0080] 7. Matrix asphalt loading: Open the hot asphalt storage tank 21 and the fifth valve 4 - 5 , and transport a determined mass of hot asphalt to the rubber powder modified asphalt high-speed shear tank 23 through the weight detector at the bottom of the hot asphalt storage tank 21 .

[0081] 8. Rubber-Crushed Asphalt Discharge: After the temperature inside the rubber-crushed asphalt high-speed shear tank 23 reaches a certain temperature and stabilizes, the high-speed shear controller 24 is activated, controlling the shear speed of the rotating high-speed shear device 25 to 3500 rpm for 30 minutes. The shear force generated by the high-speed shearing breaks down the bio-oil pretreated rubber powder agglomerates, uniformly dispersing it into micron-sized particles and forming a stable suspension. The mechanical and thermal energy generated by the shearing activates the surface active groups (e.g., C=O, -OH) of the rubber powder, which undergo physical and chemical crosslinking with the polar components in the asphalt, forming a three-dimensional network structure and improving its elastic recovery rate. After the shearing is completed, the valve at the lower discharge port 30 of the rubber-crushed asphalt high-speed shear tank 23 is opened, and the rubber-crushed asphalt is fed into the rubber-crushed asphalt storage tank 27 via the rubber-crushed asphalt conveyor 26. The stirring drive 28 located on the top of the rubber-crushed asphalt storage tank 27 is then activated, causing the stirring blades 29 to stir the rubber-crushed asphalt, thereby enhancing the stability of the rubber-crushed asphalt's properties.

[0082] The production system provided by the embodiment of the present invention has the advantages of compact structure, simple process, and good rubber powder activation effect. The modular design of the pretreatment tank and high-speed shear tank supports continuous production. At the same time, in combination with the corresponding production process, a two-stage pretreatment is performed, first with negative pressure and then with nitrogen pressurization. At a specific temperature, the negative pressure environment is first used to accelerate the opening of the internal pores of the rubber powder particles and the penetration efficiency of bio-oil. Subsequently, nitrogen pressurization is used to strengthen the filling of bio-oil into the internal pores of the rubber powder, significantly improving the activation effect of the rubber powder and laying a homogenized foundation for the subsequent preparation of modified asphalt. At the same time, the negative pressure stage can simultaneously remove residual volatile substances in the rubber powder, and the pressurization process uses nitrogen inert protection to avoid oxidative side reactions. The pretreated rubber powder and hot matrix asphalt are simultaneously heated and sheared in the high-speed shear tank, achieving secondary dispersion and interface strengthening of the rubber powder through mechanical-thermal synergy, effectively solving technical problems such as rubber powder agglomeration and phase separation in traditional processes. Bio-oil is used as the rubber powder activation medium, replacing traditional aromatic oil or coal tar, reducing the emission of toxic volatiles.

[0083] In order to verify the feasibility and effectiveness of the scheme of the present invention, the following specific examples and experiments are used to illustrate and the following comparative examples are designed for comparison.

[0084] Comparative Example 1

[0085] This comparative example provides a traditional rubber powder modification process, which specifically includes the following steps:

[0086] (1) Mixing stage: Heat the base asphalt to 180°C (compared to the traditional rubber powder modification process, the temperature is higher), add the rubber powder (not activated by bio-oil) while mixing, and stir at a constant temperature for 20 minutes; the amount of rubber powder added is 20% of the asphalt mass.

[0087] (2) Shearing stage: The mixture was sheared at a speed of 4500 r / min for 10 min.

[0088] (3) Development stage: Continue stirring at 180°C for 30 minutes until uniform, and then obtain ordinary rubber powder modified asphalt.

[0089] Comparative Example 2

[0090] This comparative example provides a conventional rubber-powder-modified asphalt production system. The main difference from the production system provided in Example 1 is that its rubber-powder pretreatment tank adopts a conventional rotary blade structure and motion mode. The specific differences are shown in Table 1 below:

[0091]

[0092] In the following implementation and experiments, the base asphalt was selected from A-70# petroleum asphalt produced by Dongguan Taihe Asphalt Co., Ltd.; the rubber powder was selected from waste truck tire rubber powder provided by Guangxi Jiaoke New Materials Technology Co., Ltd.; and the bio-oil was selected from waste plant-based bio-oil produced by Nantong Yuhao Chemical Technology Co., Ltd. The basic performance indicators of the bio-oil, rubber powder, and base asphalt used are shown in Tables 2, 3, and 4, respectively.

[0093]

[0094]

[0095]

[0096] (1) Effects of nitrogen pressurization time and shear temperature on the properties of modified asphalt

[0097] With reference to the preparation methods, systems and processes provided in Examples 1 and 2, the following groups of rubber powder modified asphalt were prepared: the rubber powder content was designed to be 20% and 30% of the mass of the base asphalt, respectively; the bio-oil content was designed to be 10% of the mass of the asphalt; the temperature inside the high-speed shear tank of the rubber powder modified asphalt was designed to be 160°C and 180°C; and the nitrogen pressurization time was designed to be 0 min, 10 min, 20 min and 30 min.

[0098] All the obtained asphalts were subjected to a Brookfield viscosity test at 160°C according to standard T0625-2011. The test results are shown in Table 5.

[0099] Table 5 Viscosity test results of different groups (I) (unit: mPa·s)

[0100]

[0101] The data in the table above shows that nitrogen pressurization times within the 20-30 minute range effectively achieve deep filling of the rubber powder pores with bio-oil. When the pressurization time exceeds 20 minutes, the viscosity decrease trend slows (for example, when the nitrogen pressurization time is extended to 30 minutes, the viscosity at 30% admixture and 160°C further decreases to 461.2 mPa·s, a decrease of only approximately 4.8% compared to 20 minutes), indicating that pore filling is near saturation at this point. Therefore, extending the pressurization time can further optimize the rubber powder pore-filling effect, but with diminishing marginal benefits. A pressurization time of 20-30 minutes is optimal to balance process efficiency and performance optimization.

[0102] The experimental results in Table 5 also demonstrate that the nitrogen pressurization process described in the present invention significantly regulates the viscosity of rubber-modified asphalt. Under the same conditions of rubber powder content and shear temperature, the viscosity of the modified asphalt decreases gradually with increasing nitrogen pressurization time (0 min to 30 min). At a 30% rubber powder content and a shear temperature of 160°C, the viscosity decreases by 55.1%, demonstrating that pressurization effectively improves rubber powder dispersibility and promotes a compensatory bio-oil release effect.

[0103] Comparison of data at different shear temperatures revealed that bio-oil-activated rubber powder treated with nitrogen pressure and then shear-modified at 180°C further reduced viscosity, demonstrating a synergistic effect between the modified shear temperature and the pressurization time during rubber powder activation. The viscosity optimization effect of pressure treatment was particularly significant for a high rubber powder content (30%), with an absolute viscosity reduction of 594.7 mPa·s (at 160°C), fully demonstrating the adaptability of the process to high-content systems. Through "bio-oil gradient activation" and "nitrogen interface engineering," this invention achieves synergistic optimization of the high- and low-temperature properties of high-content rubber powder-modified asphalt, resolving inherent limitations of conventional processes. A high content of 30% not only improves resource recycling efficiency but also imparts self-compensation properties to the material through a dynamic oil storage mechanism, providing key technical support for the application of high-content waste tire rubber powder in road construction. Furthermore, the significant viscosity improvement was maintained even at 180°C, confirming the inhibitory effect of the nitrogen inert atmosphere on rubber powder thermal oxidation.

[0104] Therefore, the experimental data from each group of this example demonstrates that nitrogen pressurization, by promoting gradient bio-oil penetration and dynamic compensation mechanisms, effectively weakens the interactions between rubber powder particles, improves rubber powder-asphalt interfacial compatibility, and thus reduces system viscosity and enhances workability. This result provides a key basis for optimizing process parameters, confirming that the present invention can achieve precise control of the rheological properties of modified asphalt by regulating the combination of pressurization time and temperature. Furthermore, the low dispersion of the experimental data confirms the precise controllability of the process parameters, meeting the stability requirements of industrial continuous production.

[0105] (2) Effects of rubber powder content and bio-oil content on the performance of modified asphalt

[0106] Referring to the preparation methods, systems, and processes provided in Examples 1 and 2, the following groups of crumb rubber-modified asphalt were prepared: the crumb rubber content was set at 20%, 25%, 30%, and 35% of the base asphalt mass, respectively; the bio-oil content was set at 10%, 12.5%, and 15% of the asphalt mass; the temperature in the high-speed shear tank for the crumb rubber-modified asphalt was set at 160°C, and the nitrogen pressurization time was set at 20 minutes. All resulting asphalts were subjected to a Brookfield viscosity test at 160°C according to Standard T0625-2011. The test results are shown in Table 6.

[0107]

[0108] The data in Table 6 show that when the crumb rubber content increases from 20% to 35%, the viscosity increases dramatically from 315.2 mPa·s to 619.8 mPa·s (a 96.5% increase) while the bio-oil content remains constant at 10%, significantly increasing the construction difficulty. However, when the bio-oil content is simultaneously increased to 15%, the viscosity of the 35% crumb rubber system decreases to 497.4 mPa·s, a 19.7% decrease compared to the 35% crumb rubber + 10% bio-oil combination. This indicates that the activation effect of the bio-oil on the crumb rubber effectively offsets the viscosity degradation caused by high crumb rubber content. In particular, at a high crumb rubber content of 30%, increasing the bio-oil content from 10% to 15% reduces the viscosity by 17.8% (from 484.6 to 398.5 mPa·s), demonstrating that the dynamic release mechanism of the bio-oil continuously improves the lubrication of the crumb rubber-asphalt interface.

[0109] When the rubber powder content exceeds 30%, the system viscosity increases at an accelerated rate. Specifically, at a bio-oil content of 15%, increasing the rubber powder content from 30% to 35% increases the system viscosity by 98.9 mPa·s. This increase is greater than the 72.9 mPa·s increase in viscosity when the rubber powder content increases from 25% to 30%. However, compared to the viscosity of 2201 mPa·s at 160°C for the modified asphalt produced by the conventional process in Comparative Example 1, the high-content system (15% bio-oil content and 35% rubber powder content) achieved a 77% reduction in viscosity, demonstrating the ability of the negative pressure-nitrogen pressurization synergistic process to control ultra-high content systems.

[0110] To further verify the adaptability of the present invention's process to ultra-high rubber-powder-modified asphalt, this example also used bio-oil-activated rubber-powder-modified asphalts obtained with rubber powder dosages designed to be 30% and 35% of the base asphalt mass, and with bio-oil dosage designed to be 15% of the base asphalt mass, as experimental groups. A conventional rubber-powder-modified asphalt prepared using the preparation process provided in Comparative Example 1 with a rubber powder dosage designed to be 20% was used as a control. Dynamic shear rheology tests and bending beam rheology tests were conducted to compare and analyze their high- and low-temperature performance characteristics. The test results are shown in Table 7. The S value indicates the low-temperature brittleness of the asphalt (a larger S indicates a harder and more brittle asphalt), while the m value reflects the stress dissipation capacity (a larger m indicates better stress dissipation capacity).

[0111] Table 7 Performance evaluation indexes of each group of modified asphalt

[0112]

[0113] It can be seen from the data in Table 7 that the modified asphalt with high content of bio-oil activated rubber powder (30%, 35%) produced by the system and process provided by the present invention still has better high and low temperature performance than the modified asphalt with ordinary rubber powder (20% content).

[0114] (3) Effect of shear temperature on modified asphalt performance

[0115] With reference to the preparation methods, systems and processes provided in Examples 1 and 2, the following groups of rubber powder modified asphalt were prepared: the rubber powder content was designed to be 20% and 30% of the mass of the base asphalt, respectively; the bio-oil content was designed to be 10% of the mass of the asphalt; the temperatures in the high-speed shear tank of the rubber powder modified asphalt were designed to be 155°C, 160°C and 165°C, respectively; and the nitrogen pressurization time was designed to be 20 minutes.

[0116] All the obtained asphalts were subjected to a Brookfield viscosity test at 160°C according to standard T0625-2011. The test results are shown in Table 8.

[0117]

[0118] The data in Table 8 demonstrates that within the shear temperature range of 155-165°C, the viscosity of the modified asphalt remains stable within a ±5% fluctuation range, demonstrating high stability. While traditional high-temperature processes (180-200°C) can reduce viscosity, they often result in bio-oil loss and unstable performance.

[0119] (IV) Effect of the rotating blade structure and motion mode of the crumb rubber pretreatment tank on the performance of modified asphalt

[0120] Referring to the production process provided in Example 2, the rubber powder content is designed to be 30% of the mass of the base asphalt, and the bio-oil content is designed to be 10% of the mass of the base asphalt.

[0121] The modified asphalt produced by the production system of Comparative Example 2 was recorded as the control group, and the modified asphalt produced by the production system provided in Example 1 was recorded as the test group. The following test was conducted in accordance with the standard "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering" JTG E20-201 (T 0661-2011).

[0122] First, the prepared unaged modified asphalt sample was heated to 163°C and then poured into an aluminum tube. Next, the aluminum tube containing the modified asphalt sample was placed in an oven at 163°C and kept at a constant temperature for 48 hours. After that, the aluminum tube was transferred to a refrigerator at -10°C and placed for 4 hours. After completing the above operations, use a knife to divide the sample below the liquid level in the aluminum tube into three equal sections, and take one-third of the samples from the top, middle and bottom to test their softening points. The softening point difference of the modified asphalt samples at the upper and lower ends of the sample tube is used as an evaluation index. The smaller the softening point difference, the smaller the degree of segregation of the modified asphalt. When the softening point difference is lower than 2.5°C, it is considered that the modified asphalt has good storage stability during transportation and storage. The results are as follows:

[0123]

[0124] It can be seen from the data in Table 9 above that the rubber-modified asphalt produced by the production system provided in Example 1 of the present invention has better stability than the rubber-modified asphalt produced by the rubber-modified asphalt pretreatment tank in the conventional production system of the control group.

[0125] (V) High and low temperature performance and anti-aging performance test

[0126] Settings for each treatment group:

[0127] Treatment Group 1: Ordinary rubber powder modified asphalt prepared by the process provided in Comparative Example 1, with the rubber powder content being 20% of the base asphalt;

[0128] Treatment group 2: According to the JTG E20-2011 specification, the ordinary rubber crumb modified asphalt prepared in treatment group 1 was subjected to thermal oxidative aging treatment using a SYD-0610 rotary thin film oven (RTFO) and a PR9300 pressure aging tester (PAV) to obtain long-term aged rubber crumb modified asphalt.

[0129] The short-term aging treatment method is as follows: set the short-term aging test temperature to 163°C±0.5°C, put 35g±0.5g of the asphalt sample to be aged into a standard sample bottle, set the ring frame rotation speed to 15r / min, and age for 85min to obtain the short-term aged asphalt sample.

[0130] The long-term aging treatment method is as follows: The long-term aging test temperature is 100°C. 50g ± 0.5g of the short-term aged asphalt sample is placed in an aging pan to form a 3.2mm thick asphalt film. The air pressure is set to 2.1 ± 0.1MPa, and the aging time is 20h ± 10min.

[0131] Treatment group 3: Referring to the preparation methods, systems and processes provided in Examples 1 and 2, the rubber powder content was designed to be 20% of the base asphalt, and the bio-oil content was designed to be 10%, to obtain bio-oil activated rubber powder modified asphalt.

[0132] Treatment group 4: Referring to the treatment method of treatment group 2, the bio-oil activated rubber powder modified asphalt prepared in treatment group 3 was subjected to thermal oxygen aging treatment to obtain long-term aged bio-oil activated rubber powder modified asphalt.

[0133] Treatment Group 5: Tall oil was used as the regeneration agent. Tall oil, a byproduct of the papermaking industry, contains a large amount of unsaturated fatty acids and a certain amount of polyunsaturated carbon-bonded fatty acids. The basic performance indicators of tall oil are shown in Table 10. The preparation process was as follows: The long-aged rubber powder-modified asphalt obtained in Treatment Group 2 was heated to 180°C, and then 10% by weight of tall oil was added. The mixture was thoroughly mixed with a stirrer to obtain a recycled rubber powder composite-modified asphalt.

[0134]

[0135] The modified asphalt obtained from each treatment group was subjected to a temperature sweep test at 64°C using a dynamic shear rheometer. The test procedure followed AASHTO T 315. The rutting factor (G* / sinδ) was used to characterize the medium- and high-temperature viscoelastic properties of the asphalt. The test results are shown in Table 11.

[0136] Bending beam rheology (BBR) tests were performed to measure the creep stiffness (S) and creep rate (m) at -18°C for the standard rubber-modified asphalt in treatment group 1, the long-aged rubber-modified asphalt in treatment group 2, the recycled rubber-modified composite asphalt in treatment group 5, the bio-oil-activated rubber-modified asphalt in treatment group 3, and the long-aged bio-oil-activated rubber-modified asphalt in treatment group 4 to evaluate their low-temperature performance. The S value indicates the low-temperature brittleness of the asphalt (a higher S indicates a higher brittleness), while the m value reflects the stress dissipation capacity (a higher m indicates a better stress dissipation capacity). The test results are shown in Table 6.

[0137] Table 11 Rutting factor and BBR test results

[0138]

[0139] The experimental results in Table 11 show that, in terms of high-temperature performance, the rutting factor of the bio-oil-activated rubber crumb modified asphalt (3218.0 Pa) is 53.9% lower than that of conventional rubber crumb modified asphalt (6982.4 Pa), confirming that the bio-oil, through the synergistic negative pressure-nitrogen pressurization process, suppresses viscoelastic degradation caused by excessive swelling of the rubber crumb. After long-term aging, the rutting factor increases by only 181.1% (9046.1 Pa), far less than the 244.7% increase (24056 Pa) of conventional rubber crumb modified asphalt. This demonstrates that the oil storage microcapsules formed by bio-oil activation under negative pressure-nitrogen pressurization can dynamically compensate for the loss of light components during aging, effectively slowing performance degradation.

[0140] In terms of low-temperature performance, the creep stiffness S value (35.8 MPa) of the bio-oil activated rubber powder modified asphalt is 72.0% lower than that of the ordinary rubber powder modified asphalt (128 MPa), and the creep rate m value (0.439) is increased by 35.5%, indicating that its low-temperature stress relaxation ability is significantly improved. After aging, the S value only increases by 45.5% (52.1 MPa), and the m value remains at 0.402, confirming the long-term protection of the low-temperature durability of the material by the dynamic release mechanism of bio-oil.

[0141] In terms of anti-aging regeneration, the rutting factor (9046.1Pa) of the long-aged bio-oil-activated rubber crumb modified asphalt was further reduced by 5.3% compared to the recycled rubber crumb composite modified asphalt (9547.4Pa). Its creep stiffness (52.1MPa) was 9.4% lower than that of the recycled composite modified asphalt (57.5MPa), and its creep rate (0.402) was increased by 3.9%. This indicates that the activated bio-oil reservoir continuously releases lightweight components during the aging process, achieving dynamic self-compensation of material properties. Furthermore, the three-dimensional oil storage network formed by the bio-oil-activated rubber crumb process through gradient infiltration has a long-term stress-buffering function. The regeneration effect is derived from the rubber crumb's internal self-repair mechanism, rather than relying on the physical addition of an external regeneration agent. Of particular note, the low-temperature performance of bio-oil-activated rubber crumb modified asphalt after aging (S=52.1, m=0.402)—without any regeneration agent—approaches or even surpasses that of a regeneration system incorporating 10% tall oil (S=57.5, m=0.387). This demonstrates the technological breakthrough of this process, which integrates material anti-aging and regeneration through an in-situ reservoir effect. Compared to traditional regeneration technologies, this process avoids the risk of high-temperature decomposition of the regeneration agent and the problem of secondary aging.

[0142] (6) Compare the performance differences between ordinary rubber powder modified asphalt (20%) and bio-oil activated rubber powder modified asphalt (30%).

[0143] Referring to the preparation methods, systems and processes provided in Examples 1 and 2, the rubber powder content is designed to be 30% of the mass of the matrix asphalt, the bio-oil content is designed to be 10% of the mass of the matrix asphalt, the temperature inside the rubber powder modified asphalt high-speed shear tank is 160°C, and the nitrogen pressurization time is 20 minutes.

[0144] Conventional rubber-modified asphalt was prepared using the process described in Comparative Example 1, with the rubber powder content designed to be 20% of the base asphalt. Temperature sweep tests were conducted at 64°C using a dynamic shear rheometer, following the AASHTO T 315 standard. The rutting factor (G* / sinδ) was used to characterize the medium- and high-temperature viscoelastic properties of the asphalt. The results are shown in Table 12.

[0145] Bending beam rheology (BBR) tests were conducted to measure the creep stiffness (S) and creep rate (m) of conventional rubber-modified asphalt and bio-oil-activated rubber-modified asphalt at -18°C to evaluate their low-temperature performance. The S value indicates the asphalt's low-temperature brittleness (a higher S indicates a harder and more brittle asphalt), while the m value reflects its stress dissipation capacity (a higher m indicates better stress dissipation). The test results are shown in Table 12.

[0146] Table 12 Rutting factor and BBR test results

[0147]

[0148] The experimental results in Table 12 indicate that the bio-oil activation process of the present invention achieves synergistic optimization of high- and low-temperature performance even with a high rubber powder dosage (30%). The rutting factor of the bio-oil-activated rubber powder-modified asphalt is 2.6% higher than that of conventional rubber powder-modified asphalt. This enhanced high-temperature rutting resistance stems from the synergistic effect of the dense oil film formed by nitrogen pressurization and the three-dimensional network structure of the rubber powder, effectively improving the elastic recovery properties of the asphalt. Of particular note, the creep stiffness (97.4 MPa) is 23.9% lower than that of the conventional rubber powder system, while the creep rate is increased by 11.4%, demonstrating that the dynamic release mechanism of the bio-oil effectively improves the flexibility of the rubber powder-asphalt interface.

[0149] In summary, unlike the contradictory phenomenon in traditional technology where high rubber powder dosage leads to improved high-temperature performance and deteriorated low-temperature performance, the present invention has achieved a breakthrough in the positive correlation improvement of high- and low-temperature performance of high-dosage rubber powder modified asphalt through the synergistic mechanism of the in-situ storage effect of bio-oil and nitrogen inert interface modification, which can provide key technical support for the resource utilization of high-proportion waste tire rubber powder.

[0150] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing high-content bio-oil activated rubber powder modified asphalt, characterized in that: The following steps are involved: S1. Stirring and mixing the rubber powder and bio-oil at 110±5°C and a negative pressure of -0.08 to -0.095 MPa for 45 to 60 minutes to allow the bio-oil to initially penetrate the rubber powder. Subsequently, switching to nitrogen pressure at 0.3 to 0.5 MPa and stirring and mixing for 20 to 30 minutes allows the bio-oil to fill the pores within the rubber powder, thereby obtaining bio-oil-activated rubber powder. The nitrogen pressure is gradually increased at a rate of 0.03 to 0.07 MPa / min to a preset pressure. The process of step S1 is carried out in a rubber powder pretreatment tank. The rubber powder pretreatment tank is equipped with a stirring device, which includes a rotary drive and rotary blades. The rotary blades are arranged in the tank body. The rotary blades adopt an upper, middle and lower three-layer combined blade configuration. When working, the rotary drive controls the rotation speed of the three layers of blades respectively. The rotation speed of the upper blades is 60-90 rpm, which is used to generate strong shear force to break up rubber powder agglomerates; the rotation speed of the middle blades is 30-60 rpm, which is used to promote radial diffusion; the rotation speed of the lower blades is 15-30 rpm, which is used to enhance axial circulation and scrape the wall; at the same time, the rotary drive also controls the rotating blades as a whole to perform the following cyclic motion: forward rotation for 5 minutes, pause for 10 seconds, and then reverse rotation for 3 minutes; S2. Add the bio-oil activated rubber powder prepared in S1 to the hot matrix asphalt, control the temperature at 160±5°C, and the shear speed at 2500-5500 rpm; and perform shear mixing for 20-60 minutes to obtain the bio-oil activated rubber powder modified asphalt. Calculated based on the mass of base asphalt, the amount of rubber powder added is 20~35% of the base asphalt; the amount of bio-oil added is 10%~15% of the base asphalt.

2. The method for preparing a high-content bio-oil activated rubber powder modified asphalt according to claim 1, characterized in that: The bio-oil in step S1 is a renewable plant-based pyrolysis product rich in light components, which is prepared from agricultural and forestry wastes rich in cellulose, hemicellulose and lignin. The agricultural and forestry wastes include corn straw, rice husks, wheat straw and sawdust.

3. The method for preparing a high-content bio-oil activated rubber powder modified asphalt according to claim 1, characterized in that: The rubber powder in step S1 is a particle obtained by mechanically crushing waste tires, or a particle obtained by grinding waste rubber conveyor belts or waste rubber seals at room temperature, and the particle size range of the particle is controlled to be 0.3mm~0.6mm.

4. A production system for high-dosage bio-oil activated rubber powder modified asphalt capable of implementing the preparation method described in any one of claims 1 to 3, characterized in that: It includes a rubber powder pretreatment tank, a rubber powder modified asphalt high-speed shear tank and a rubber powder modified asphalt storage tank which are connected in sequence; The rubber powder pretreatment tank and the rubber powder modified asphalt high-speed shear tank are connected via a bio-oil pretreatment rubber powder conveyor, and the rubber powder modified asphalt high-speed shear tank and the rubber powder modified asphalt storage tank are connected via a rubber powder modified asphalt conveyor; The system also includes a rubber powder conveying assembly, a bio-oil pumping assembly, a nitrogen pressurizing assembly, and a vacuum pump assembly connected to the rubber powder pretreatment tank; the rubber powder conveying assembly is used to quantitatively convey rubber powder to the rubber powder pretreatment tank, the bio-oil pumping assembly is used to quantitatively pump bio-oil to the rubber powder pretreatment tank, the nitrogen pressurizing assembly is used to nitrogen pressurize the rubber powder pretreatment tank, and the vacuum pump assembly is used to achieve negative pressure conditions in the rubber powder pretreatment tank; and the system also includes a hot asphalt conveying assembly, which is used to convey hot base asphalt to the rubber powder modified asphalt high-speed shear tank. The rubber powder pretreatment tank is provided with a temperature control device and a stirring device; the rubber powder modified asphalt high-speed shearing tank is also provided with a temperature control device and a stirring device; the rubber powder modified asphalt storage tank is also provided with a stirring device.

5. The production system of high-content bio-oil activated rubber powder modified asphalt according to claim 4, characterized in that: The temperature control device of the rubber powder pretreatment tank includes a jacketed thermal oil circulation heating device and a first PID temperature controller, which is used to control the temperature in the rubber powder pretreatment tank at 110±5°C; The stirring device includes a rotary driver and a rotary blade, and the rotary driver can drive the rotary blade to rotate the material in the stirring tank; The rotating blades of the rubber powder pretreatment tank are arranged in the tank body, and adopt a three-layer combined blade configuration of upper, middle and lower layers. The upper blades are folding paddle blades, the middle blades are spiral belt blades, and the lower blades are anchor blades. The gap between the outer edge of the anchor blade and the tank wall is ≤5mm, and a polytetrafluoroethylene or wear-resistant rubber scraper is provided; the rotary driver is arranged at the top of the rubber powder pretreatment tank, and is used to control the speed, rotation time and rotation direction of the rotating blades.

6. The production system of high-content bio-oil activated rubber powder modified asphalt according to claim 4, characterized in that: The temperature control device of the rubber powder modified asphalt high-speed shear tank includes a jacketed thermal oil circulation heating device and a second PID temperature controller, which is used to control the temperature in the rubber powder modified asphalt high-speed shear tank at 160±5℃; The stirring device includes a high-speed shearing controller and a rotating high-speed shearing device. The high-speed shearing controller can drive the rotating high-speed shearing device to rotate the material in the stirring tank and control the shearing speed and shearing time of the rotating high-speed shearing device. The stirring device of the rubber powder modified asphalt storage tank includes a stirring blade and a stirring driver. The stirring blade is arranged in the rubber powder modified asphalt storage tank, and the stirring driver is arranged on the top of the rubber powder modified asphalt storage tank. The stirring driver is used to drive the stirring blade to rotate the material in the stirring tank and control the stirring speed, rotation time and rotation direction of the stirring blade.

7. The production system of high-content bio-oil activated rubber powder modified asphalt according to claim 4, characterized in that: The rubber powder conveying assembly includes a rubber powder storage box, a rubber powder conveying pipe, a fan, a spiral metering scale and a first valve. The rubber powder conveying pipe connects the rubber powder storage box and the rubber powder pretreatment tank. The first valve, fan and spiral metering scale are sequentially arranged on the rubber powder conveying pipe. The bio-oil pumping assembly includes a bio-oil storage tank, a bio-oil delivery pipe, a metering pump, and a second valve. The bio-oil delivery pipe connects the bio-oil storage tank and the rubber powder pretreatment tank. The second valve and the metering pump are sequentially arranged on the bio-oil delivery pipe. The nitrogen pressurizing assembly includes a nitrogen tank, a nitrogen pressurizing pipe, a third valve, a second pressure controller, and a pressure pump. The nitrogen pressurizing pipe is used to connect the nitrogen tank and the rubber powder pretreatment tank. The third valve, the second pressure controller, and the pressure pump are arranged on the nitrogen pressurizing pipe. The pressure pump is used to quickly fill the rubber powder pretreatment tank with nitrogen and pressurize it. The second pressure controller is used to control the pressure in the rubber powder pretreatment tank at 0.3-0.5 MPa. A pump-suction nitrogen concentration detector is provided at the bottom of the nitrogen tank for detecting the nitrogen concentration in the nitrogen tank. The vacuum pump assembly includes a vacuum pump, a vacuum extraction pipeline, a fourth valve and a first pressure controller. The vacuum pump is connected to the bottom of the rubber powder pretreatment tank through the vacuum extraction pipeline. The fourth valve and the first pressure controller are arranged on the vacuum extraction pipeline. The first pressure controller is electrically connected to the vacuum pump and is used to control the pressure in the rubber powder pretreatment tank at -0.08~-0.095MPa.

8. The production system of high-content bio-oil activated rubber powder modified asphalt according to claim 4, characterized in that: The hot asphalt conveying assembly includes a hot asphalt storage tank, a hot asphalt conveyor, and a fifth valve. The hot asphalt conveyor is connected to the hot asphalt storage tank and the rubber powder modified asphalt high-speed shear tank. The fifth valve is arranged on the hot asphalt conveyor. A weight detector is provided at the bottom of the hot asphalt storage box to control the mass of the hot asphalt added to the rubber-modified asphalt high-speed shear tank. A microwave heating device is installed in the hot asphalt storage box to control the temperature inside the hot asphalt storage box at 150±10℃.

9. A high-content bio-oil activated rubber powder modified asphalt produced by the preparation method according to any one of claims 1 to 3 or the production system according to any one of claims 4 to 8.

Images