Modified asphalt based on nano material reinforcement and preparation method thereof

Abstract

The invention relates to the technical field of high polymer material and polymer modification, in particular to modified asphalt based on nano material reinforcement and a preparation method, the modified asphalt comprises matrix asphalt subjected to molecular cutting and compounding, a nano titanium dioxide-graphene-carbon nano tube ternary composite material, zwitter-ion and silane synergistically modified nano montmorillonite, the rubber powder subjected to special treatment, the bio-based and traditional compound plasticizer and the 2-mercaptobenzimidazole and sulfur compound stabilizer are synergistically modified. The modified asphalt has the advantages of excellent performance, high-temperature stability, low-temperature crack resistance, strong aging resistance, efficient and environment-friendly preparation process, low energy consumption, short period and good nanometer material dispersion, and adopts the bio-based plasticizer to promote the green development of the asphalt industry.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials and polymer modification, and specifically to a modified asphalt strengthened by nano materials and a preparation method thereof. Background Art

[0002] As an indispensable basic material in road construction, the performance of asphalt directly affects the service life of the road and the driving safety. Traditional matrix asphalt exposes many performance shortcomings when facing complex and changeable natural environments and increasing traffic loads.

[0003] In high-temperature environments, matrix asphalt is prone to softening, resulting in diseases such as ruts and bumps on the road surface. According to statistics, during the high-temperature period in summer, the rut depth of some busy traffic sections can increase by 1-2 centimeters per year, seriously affecting road smoothness and vehicle driving comfort, and increasing the potential risk of traffic accidents. In low-temperature conditions, asphalt becomes brittle, the crack resistance drops sharply, and cracks are prone to appear. Moisture seeps into the roadbed through the cracks, accelerating the damage of the road structure. In cold regions in the north, after each winter, the number and length of cracks on the road will increase significantly, not only resulting in high maintenance costs but also affecting the normal use of the road.

[0004] To improve the performance of asphalt, people began to use modified asphalt. In the early days, rubber powder was commonly used to modify asphalt. Although it improved the flexibility and fatigue resistance of asphalt to a certain extent, the compatibility between rubber powder and asphalt was limited, segregation was prone to occur, and the improvement of the high-temperature stability of asphalt was insufficient. Subsequently, polymer-modified asphalt emerged, such as using polymers like SBS (styrene-butadiene-styrene block copolymer). However, such modified asphalt has problems such as uneven polymer dispersion, high energy consumption, and high cost during production and use. Moreover, over time, the polymer is prone to aging, resulting in a gradual weakening of the modification effect.

[0005] In recent years, due to their unique size effect, surface effect, and quantum size effect, nano materials have brought new opportunities for asphalt modification. Nano titanium dioxide can improve the anti-ultraviolet aging performance of asphalt, but the dispersion of single nano titanium dioxide is poor, it is easy to agglomerate in asphalt, and it is difficult to fully exert its advantages. Nano montmorillonite can improve the high-temperature stability of asphalt, but the interfacial bonding force between nano montmorillonite and asphalt in conventional modification methods is insufficient, limiting the extent of performance improvement.

[0006] Meanwhile, there are also some problems in the existing asphalt preparation processes. The traditional stirring and mixing methods are difficult to achieve efficient and uniform dispersion of nanomaterials in asphalt, resulting in unstable properties of modified asphalt. Moreover, some preparation processes have high energy consumption and long time, which are not conducive to large-scale industrial production, energy conservation and environmental protection. Today, with the increasing awareness of environmental protection, developing environmentally friendly plasticizers and stabilizers is also an important issue faced by the asphalt industry. Currently, most commonly used plasticizers are petroleum-based products, which pose potential hazards to the environment, and there are few effective environmentally friendly alternatives. In terms of stabilizers, the traditional sulfur used alone has limited effect and may affect other properties of asphalt to a certain extent. Therefore, it is urgent to develop a modified asphalt based on nanomaterial reinforcement with excellent performance and an efficient and environmentally friendly preparation process. Summary of the Invention

[0007] (I) Technical Problems to be Solved In view of the deficiencies of the prior art, the present invention provides a modified asphalt based on nanomaterial reinforcement and a preparation method thereof.

[0008] (II) Technical Solutions A modified asphalt based on nanomaterial reinforcement is composed of the following components by weight: Matrix asphalt: 60 - 80 parts, and a customized matrix asphalt processed by molecular tailoring technology is selected. This technology uses aluminum chloride as a catalyst to selectively cut and recombine the molecular chains of AH-70 and AH-90 matrix asphalt under mild conditions; Nano-titanium dioxide - graphene - carbon nanotube ternary composite nanomaterial: 5 - 15 parts. Through chemical vapor deposition, nano-titanium dioxide and carbon nanotubes are in-situ grown on the surface of graphene oxide. During the reaction process, isopropyl titanate is used as the titanium source and xylene is used as the carbon source. The reaction formula is as follows:

[0009] Nano-montmorillonite: 3 - 10 parts, which is co-modified by an amphoteric ionic surfactant dodecyl dimethyl betaine and an organosilane coupling agent γ-aminopropyltrimethoxysilane. During the modification process, the amphoteric ionic surfactant first enters the interlayer of montmorillonite through ion exchange to expand the layer spacing, and then the organosilane coupling agent reacts with the hydroxyl groups on the surface of montmorillonite. The reaction formula is:

[0010] The structure of the dodecyl dimethyl betaine is:

[0011] Rubber powder: 8 - 20 parts, which is waste tire rubber powder treated by microwave desulfurization and plasma activation, significantly improving the reaction activity and compatibility of rubber powder and asphalt; Plasticizer: 2 - 6 parts, using a bio - based plasticizer and dioctyl phthalate in compound; the bio - based plasticizer is obtained by polycondensation of adipic acid and 1,3 - propanediol under the action of dibutyltin dilaurate. The structure of the above - mentioned bio - based plasticizer is:

[0012] The reaction formula is:

[0013] Stabilizer: 1 - 3 parts, compounded by 2 - mercaptobenzimidazole and sulfur; at 165℃ - 185℃, 2 - mercaptobenzimidazole first reacts with the active groups in asphalt, and then sulfur participates in the cross - linking reaction. The structural formula of the above - mentioned 2 - mercaptobenzimidazole is:

[0014] Preferably, after the custom - made matrix asphalt is molecularly tailored, the width of its average molecular weight distribution is reduced by 15% - 25%, making the performance more stable and uniform.

[0015] Preferably, in the nano - titanium dioxide - graphene - carbon nanotube ternary composite nanomaterial, the included angle between the carbon nanotubes and the graphene sheets is 30° - 60°, forming a unique reinforcement network.

[0016] Preferably, the exfoliation rate of the synergistically modified nano - montmorillonite in asphalt reaches 70% - 80%, effectively improving the performance of asphalt.

[0017] Preferably, the oxygen - containing functional groups on the surface of the rubber powder after microwave desulfurization and plasma activation treatment increase by 30% - 40%, improving the binding force with asphalt.

[0018] Preferably, the glass transition temperature of the bio - based plasticizer is - 40℃ - - 30℃, meeting the low - temperature performance requirements of asphalt.

[0019] Preferably, according to the high - efficiency dispersion preparation process of the nano - material - enhanced modified asphalt described in any one of the above, it includes the following steps: Matrix asphalt pretreatment: Add the AH - 70 and AH - 90 matrix asphalts treated by molecular tailoring technology to a reaction kettle equipped with stirring and temperature control devices according to a ratio, and stir at a speed of 200 - 300 r / min for 30 - 40 minutes at 135 - 145℃; Nano - material dispersion: Add the nano - titanium dioxide - graphene - carbon nanotube ternary composite nanomaterial and the synergistically modified nano - montmorillonite to the pre - heated matrix asphalt, and use a high - shear emulsifier equipped with a specially designed multi - layer serrated shear head to shear and disperse at a speed of 6000 - 7000 r / min for 40 - 50 minutes, while applying ultrasonic wave assistance dispersion with a frequency of 25 - 35 kHz to obtain mixture A; Addition of rubber powder: Add the rubber powder treated by microwave desulfurization and plasma activation to the above mixture A, and react at 175 - 185 °C with a stirring speed of 350 - 450 r / min for 80 - 100 minutes. Nitrogen is introduced for protection during the reaction; Addition of additives: Sequentially add the bio - based plasticizer and the compound plasticizer of dioctyl phthalate, and the compound stabilizer of 2 - mercaptobenzimidazole and sulfur. Stir at 165 - 175 °C in a cooperative manner of magnetic stirring and mechanical stirring for 40 - 50 minutes, where the magnetic stirring intensity is 0.1 - 0.2 T; Post - treatment: Place the mixed modified asphalt at 155 - 165 °C in a vacuum environment with a vacuum degree of - 0.085 - - 0.095 MPa for heat preservation and static settlement for 15 - 25 minutes to remove air bubbles and obtain the final product.

[0020] Preferably, when pre - treating the matrix asphalt, the inner wall of the reaction kettle is coated with polytetrafluoroethylene to reduce asphalt adhesion.

[0021] Preferably, in the step of dispersing the nanomaterials, the ultrasonic power is 300 - 500 W to enhance the dispersion effect.

[0022] Preferably, in the step of adding additives, first add the plasticizer and stir for 20 - 30 minutes, then add the stabilizer and continue stirring for 20 - 30 minutes to ensure full reaction.

[0023] (III) Beneficial technical effects Compared with the existing technology, the beneficial effects of the present invention are: 1. After the customized matrix asphalt is treated by molecular tailoring technology and compounded, its performance stability is greatly improved, and the width of the average molecular weight distribution is reduced by 15% - 25%, making the asphalt perform more stably and uniformly in different environments. The unique structure of the nano - titanium dioxide - graphene - carbon nanotube ternary composite nanomaterial endows the asphalt with excellent anti - aging, conductive and mechanical strengthening properties.

[0024] 2. Nano - titanium dioxide effectively absorbs ultraviolet light, and the network structure formed by carbon nanotubes and graphene enhances the strength and toughness of the asphalt. After testing, the anti - ultraviolet aging time of the modified asphalt is extended and the tensile strength is increased. The exfoliation rate of the synergistically modified nano - montmorillonite in the asphalt reaches 70% - 80%, greatly improving the high - temperature stability of the asphalt and reducing the rut depth. After the rubber powder is treated by microwave desulfurization and plasma activation, its binding force with the asphalt is enhanced, improving the flexibility and anti - fatigue performance of the asphalt. The compound of the bio - based plasticizer and DOP improves the environmental performance while ensuring the low - temperature flexibility. The stabilizer compounded with sulfur - and nitrogen - containing heterocyclic compounds significantly improves the stability and durability of the asphalt.

[0025] 3. The efficient dispersion preparation process realizes the efficient and uniform dispersion of nanomaterials in asphalt through special equipment and process parameter settings. The high-shear emulsifier is combined with ultrasonic-assisted dispersion, and the specially designed shear head ensures the uniform distribution of nanomaterials. The energy consumption of the entire preparation process is reduced, the production cycle is shortened, the production efficiency is improved, the production cost is reduced, which is conducive to large-scale industrial production. Moreover, measures such as the polytetrafluoroethylene coating on the inner wall of the reaction kettle, nitrogen protection, and vacuum degassing further ensure the stability of product quality and performance. Brief Description of the Drawings

[0026] Figure 1 is a flowchart of the production of modified asphalt strengthened by nanomaterials proposed by the present invention; Figure 2 Column comparison chart of penetration, softening point and ductility of examples and comparative examples; Figure 3 Cost and environmental protection index comparison chart of examples and comparative examples; Figure 4 is a radar comparison chart made after unifying the dimensions of the comprehensive performance data of examples and comparative examples. Detailed Description of the Invention

[0027] According to Figures 1 to 4 , the detailed implementation manners of the present invention are as follows: Example 1 Pretreatment of matrix asphalt: Add 45 parts of AH-70 matrix asphalt and 30 parts of AH-90 matrix asphalt treated by molecular tailoring technology into a reaction kettle with a polytetrafluoroethylene-coated inner wall. Set the reaction kettle temperature to 135 °C, turn on the stirring device, and stir at a speed of 200 r / min for 30 minutes to fully mix the two matrix asphalts evenly.

[0028] Dispersion of nanomaterials: Add 7 parts of nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterials and 4 parts of nano-montmorillonite synergistically modified by zwitterionic surfactant and organosilane coupling agent to the above-preheated matrix asphalt. Use a high-shear emulsifier equipped with a multi-layer serrated shear head to perform shear dispersion at a speed of 6000 r / min to obtain mixture A. At the same time, turn on the ultrasonic device, set the ultrasonic frequency to 25 kHz, the power to 300 W, and disperse for 40 minutes.

[0029] Addition of rubber powder: Add 10 parts of rubber powder treated by microwave desulfurization (treated at a frequency of 2.45 GHz and a power of 500 W for 3 minutes) and plasma activation (treated in an argon atmosphere and a voltage of 500 V for 1 minute) to mixture A. Raise the reaction kettle temperature to 175 °C and react at a stirring speed of 350 r / min for 80 minutes, and continuously introduce nitrogen for protection during this period.

[0030] Additive addition: First, add 1 part of bio-based plasticizer (polypropylene adipate) and 1 part of dioctyl phthalate (DOP). At 165 °C, stir for 20 minutes by the synergistic method of magnetic stirring (intensity 0.1 T) and mechanical stirring, then add 0.5 part of 2-mercaptobenzimidazole and 0.5 part of sulfur, and continue stirring for 20 minutes.

[0031] Post-treatment: Place the mixed modified asphalt in a vacuum environment with a vacuum degree of -0.085 MPa at 155 °C and keep it static for 15 minutes to remove air bubbles, obtaining the final modified asphalt product.

[0032] Example 2 Matrix asphalt pretreatment: Add 50 parts of AH-70 matrix asphalt treated by molecular tailoring technology and 25 parts of AH-90 matrix asphalt to the reaction kettle, set the temperature at 140 °C, and stir at a speed of 250 r / min for 35 minutes.

[0033] Nanomaterial dispersion: Add 10 parts of nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial and 6 parts of synergistic modified nano-montmorillonite. The high-shear emulsifier shears at a speed of 6500 r / min, the ultrasonic frequency is 30 kHz, the power is 400 W, and disperse for 45 minutes.

[0034] Rubber powder addition: Put in 15 parts of specially treated rubber powder, adjust the temperature of the reaction kettle to 180 °C, stir at 400 r / min for 90 minutes, and introduce nitrogen for protection.

[0035] Additive addition: First, add 1.5 parts of bio-based plasticizer and 1.5 parts of DOP. At 170 °C, stir for 30 minutes by the synergistic method of magnetic stirring (intensity 0.15 T) and mechanical stirring, then add 1 part of 2-mercaptobenzimidazole and 0.5 part of sulfur and stir for 20 minutes.

[0036] Post-treatment: Let it stand for 20 minutes under 160 °C and -0.09 MPa vacuum to obtain modified asphalt.

[0037] Example 3 Matrix asphalt pretreatment: Add 55 parts of AH-70 matrix asphalt treated by molecular tailoring technology and 20 parts of AH-90 matrix asphalt to the reaction kettle, set the temperature at 145 °C, and stir at a speed of 300 r / min for 40 minutes.

[0038] Nanomaterial dispersion: Add 13 parts of nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial and 8 parts of synergistic modified nano-montmorillonite. The high-shear emulsifier shears at 7000 r / min, the ultrasonic frequency is 35 kHz, the power is 500 W, and disperse for 50 minutes.

[0039] Addition of rubber powder: Add 20 parts of specially treated rubber powder. Raise the temperature of the reaction kettle to 185°C, stir at 450 r / min for 100 minutes, and protect with nitrogen.

[0040] Addition of additives: First, add 2 parts of bio-based plasticizer and 1 part of DOP. Stir magnetically (intensity 0.2 T) and mechanically at 175°C for 30 minutes in cooperation. Then add 1 part of 2-mercaptobenzimidazole and 1 part of sulfur and stir for 20 minutes.

[0041] Post-treatment: Let it stand at 165°C and -0.095 MPa vacuum for 25 minutes to obtain modified asphalt.

[0042] Comparative example Use 75 parts of AH-70 base asphalt without being treated by molecular tailoring technology. Directly add 5 parts of ordinary nano-titanium dioxide, 3 parts of unmodified nano-montmorillonite, and 12 parts of rubber powder without special treatment. Stir at 170°C for 90 minutes. Then add 2 parts of dioctyl phthalate and 1 part of sulfur and continue to stir for 60 minutes without vacuum treatment to obtain the asphalt product for comparison.

[0043] The test results show that Examples 1-3 are significantly superior to the comparative example in key performance indicators. Specifically, for Example 1, the penetration measured at 25°C is 6.0 mm, the softening point reaches 65°C, the ductility test result at 5°C is 30 cm, the rutting dynamic stability is as high as 4500 times / mm, and the penetration retention rate after aging is 70%; the performance of Example 2 is further improved, with a penetration of 5.5 mm, a softening point of 68°C, a ductility of 35 cm, a rutting dynamic stability of 5000 times / mm, and an aging retention rate of 75%; for the most excellent Example 3, the respective indicators are a penetration of 5.0 mm, a softening point of 70°C, a ductility of 40 cm, a rutting dynamic stability of 5500 times / mm, and an aging retention rate of 80%. In contrast, the comparative example only shows a penetration of 8.0 mm, a softening point of 50°C, and a ductility of 15 cm, and other key performance indicators do not meet the test standards.

[0044] It can be seen from the above three examples and one comparative example that the penetration of Examples 1-3 is relatively smaller than that of the comparative example, indicating higher hardness; the softening point is significantly higher than that of the comparative example, indicating better high-temperature stability; the ductility is greater, reflecting better low-temperature crack resistance; the rutting dynamic stability is much higher than that of the comparative example, meaning stronger rutting resistance; the residual penetration ratio after aging is also higher than that of the comparative example, showing better anti-aging performance. Considering all performance indicators, the modified asphalt of this application is superior to the comparative example in terms of high-temperature stability, low-temperature crack resistance, and anti-aging performance, with significant performance improvement.

[0045] Comparison table of cost and environmental protection indicators between examples and comparative examples:

[0046] Conclusion: Although the raw material cost of the examples is slightly higher than that of the comparative examples, the production energy consumption is significantly reduced, and the use of bio-based components improves the environmental friendliness of the product, meeting the requirements of sustainable development. During long-term use, due to its excellent performance, the road maintenance cost can be reduced, and the comprehensive benefits are more prominent.

[0047] Comprehensive data comparison table of the performance of examples and comparative examples:

[0048] Conclusion: This table comprehensively presents the differences between the examples and the comparative examples in multiple key performance indicators. The examples are superior to the comparative examples in terms of penetration, softening point, ductility, rutting dynamic stability, residual penetration ratio after aging, and elastic recovery rate, etc., intuitively demonstrating the excellent performance improvement of the modified asphalt of this application in terms of high-temperature stability, low-temperature crack resistance, anti-aging property, and elasticity.

[0049] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modified asphalt based on nanomaterial reinforcement, characterized in that: The invention is composed of the following components by weight: base asphalt: 60-80 parts, nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial: 5-15 parts, nano-montmorillonite: 3-10 parts, rubber powder: 8-20 parts, plasticizer: 2-6 parts, stabilizer: 1-3 parts; Base asphalt: Customized base asphalt treated with molecular tailoring technology is used; this technology uses aluminum chloride as a catalyst to selectively cut and reorganize the molecular chains of AH-70 and AH-90 base asphalt under mild conditions; Nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial: Nano-titanium dioxide and carbon nanotubes are in situ grown on the surface of graphene oxide by chemical vapor deposition. During the reaction, isopropyl titanate is used as the titanium source and xylene is used as the carbon source. Nano-montmorillonite: Synergistically modified by zwitterionic surfactant dodecyl dimethyl betaine and organosilane coupling agent γ-aminopropyl trimethoxysilane; during the modification process, the zwitterionic surfactant first enters the interlayer of montmorillonite through ion exchange, and then the organosilane coupling agent reacts with the hydroxyl groups on the surface of montmorillonite; Rubber powder: The rubber powder from waste tires is treated by microwave desulfurization and plasma activation, which significantly improves the reactivity and compatibility of rubber powder with asphalt; Plasticizer: A bio-based plasticizer is compounded with dioctyl phthalate; the bio-based plasticizer is prepared by polycondensation of adipic acid and 1,3-propylene glycol under the action of dibutyltin dilaurate; Stabilizer: It is a compound of 2-mercaptobenzimidazole and sulfur. At 165℃ - 185℃, 2-mercaptobenzimidazole first reacts with the active groups in the asphalt, and then the sulfur participates in the cross-linking reaction.

2. The modified asphalt reinforced by nanomaterials according to claim 1, characterized in that: After molecular tailoring, the average molecular weight distribution width of customized matrix asphalt is reduced by 15%-25%.

3. The modified asphalt reinforced by nanomaterials according to claim 1, characterized in that: In the nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial, the angle between the carbon nanotube and the graphene sheet is 30°-60°.

4. The modified asphalt reinforced by nanomaterials according to claim 1, characterized in that: The stripping rate of synergistically modified nano-montmorillonite in asphalt reaches 70%-80%.

5. The modified asphalt reinforced by nanomaterials according to claim 1, characterized in that: The oxygen-containing functional groups on the surface of rubber powder increased by 30%-40% after microwave desulfurization and plasma activation treatment.

6. The modified asphalt reinforced by nanomaterials according to claim 1, characterized in that: The glass transition temperature of bio-based plasticizers is -40℃--30℃.

7. An efficient dispersion preparation process for preparing the modified asphalt reinforced by nanomaterials according to any one of claims 1 to 6, characterized in that: The following steps are involved: Base asphalt Pretreatment: Add the AH-70 and AH-90 base asphalts treated by molecular tailoring technology into a reactor equipped with a stirring and temperature control device in proportion, and stir at 135-145°C and 200-300r / min for 30-40 minutes; Nanomaterial dispersion: nano-titanium dioxide-graphene-carbon nanotube ternary composite nanomaterial and synergistically modified nano-montmorillonite are added to the preheated matrix asphalt, and a high shear emulsifier equipped with a multi-layer serrated shear head is used to shear and disperse at a speed of 6000-7000r / min for 40-50 minutes, and ultrasonic waves with a frequency of 25-35kHz are applied to assist dispersion to obtain a mixture A; Adding rubber powder: adding the rubber powder treated by microwave desulfurization and plasma activation to the above mixture A, reacting at 175-185°C and stirring at 350-450r / min for 80-100 minutes, and introducing nitrogen protection during the reaction; Additive addition: add bio-based plasticizer and dioctyl phthalate compound plasticizer, 2-mercaptobenzimidazole and sulfur compound stabilizer in sequence, stir for 40-50 minutes at 165-175°C using magnetic stirring and mechanical stirring, wherein the magnetic stirring intensity is 0.1-0.2T; Post-treatment: The mixed modified asphalt is placed at 155-165°C in a vacuum environment with a vacuum degree of -0.085 to -0.095 MPa for 15-25 minutes to remove bubbles and obtain the final product.

8. The efficient dispersion preparation process according to claim 7, characterized in that: During the pretreatment of the matrix asphalt, the inner wall of the reactor is coated with polytetrafluoroethylene.

9. The efficient dispersion preparation process according to claim 7, characterized in that: In the nanomaterial dispersion step, the ultrasonic power is 300-500W.

10. The high-efficiency dispersion preparation process according to claim 7, characterized in that: In the additive adding step, first add the plasticizer and stir for 20-30 minutes, then add the stabilizer and continue stirring for 20-30 minutes.

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