Low-grade road asphalt and method for preparing the same

Abstract

This application relates to a low-grade road asphalt, comprising the following components in parts by weight: 90-110 parts base asphalt, 0.2-0.5 parts vulcanizing agent, 9-13 parts filler component, 2-8 parts compatibilizer, and 0.1-0.5 parts stabilizer; the filler component includes composite sugarcane fiber and modified montmorillonite. This application has the effect of improving the durability of asphalt.

Description

Technical Field

[0001] This application relates to the field of asphalt, and in particular to a low-grade road asphalt and a method for preparing the same. Background Technology

[0002] Low-grade road asphalt has significant advantages in improving pavement modulus and rutting resistance due to its low penetration, high viscosity, and high softening point. It has been applied and promoted in many projects in my country, such as the Shanghai-Shaanxi Expressway, Hefei-Zhoushan Expressway, and Beijing-Harbin Expressway.

[0003] Currently, conventional low-grade road asphalt is mostly prepared using straight-run distillation and shallow oxidation processes, with its core weakness being a severe deficiency in aging resistance. During long-term road service, asphalt is subjected to the coupled effects of continuous heat and oxygen, ultraviolet radiation, and rainwater erosion, causing rapid volatilization of lightweight components and irreversible aggregation of asphaltene, leading to a sharp deterioration in the stability of the colloidal system. Macroscopically, this manifests as a significant decrease in asphalt ductility, increased embrittlement, and a marked reduction in adhesion to aggregates, resulting in early road defects such as loosening, particle loss, and cracking, significantly shortening the road's service life and increasing the overall life-cycle maintenance cost. Summary of the Invention

[0004] In order to improve the aging resistance of asphalt, this application provides a low-grade road asphalt and a method for preparing the same.

[0005] Firstly, this application provides a low-grade road asphalt solution, which adopts the following technical solution: A low-grade road asphalt comprises the following components in parts by weight: The composition includes 90-110 parts base asphalt, 0.2-0.5 parts vulcanizing agent, 9-13 parts filler component, 2-8 parts compatibilizer, and 0.1-0.5 parts stabilizer. The filler components include composite sugarcane fiber and modified montmorillonite.

[0006] By adopting the above technical solution, the matrix asphalt serves as a continuous phase, providing low-grade asphalt with inherent high modulus and high-temperature rutting resistance. The vulcanizing agent cross-links with the asphalt to construct a sulfur bridge network, effectively reducing the aging and aggregation of the asphalt. The filler component is a combination of composite sugarcane fiber and modified montmorillonite. The layered nanostructure of the modified montmorillonite forms a barrier in the asphalt, blocking the penetration of oxygen and ultraviolet light, thus reducing the aging reaction from the source. The composite sugarcane fiber captures aging free radicals through functional components, terminating the aging chain reaction, and strengthens the mechanical strength of the asphalt with a three-dimensional fiber network, inhibiting low-temperature cracking and improving the problem of poor aging resistance of asphalt.

[0007] Preferably, the modified montmorillonite comprises montmorillonite, silica, and octadecyltrimethylammonium bromide.

[0008] By adopting the above technical solution, the natural layered nanostructure of montmorillonite can effectively block oxygen, ultraviolet light, and other substances from penetrating into the asphalt. The grafted silica introduces a large number of active silanol groups on the surface of the montmorillonite layers, increasing the surface roughness of the layers, improving the interfacial bonding with the asphalt matrix, and providing reaction sites for the formation of hydrogen bonds and covalent bonds with the surface active groups of composite sugarcane fiber, thus strengthening the chemical bonds of the two fillers. Octadecyltrimethylammonium bromide, as a cationic intercalating agent, is inserted into the interlayer of montmorillonite through ion exchange, significantly expanding the interlayer spacing, reducing the van der Waals forces of the layers, and promoting the exfoliation dispersion of montmorillonite in asphalt. Furthermore, its long alkyl chain can improve the compatibility of montmorillonite with non-polar asphalt and reduce the occurrence of agglomeration, thereby further improving the stability and aging resistance of asphalt.

[0009] Preferably, the modified montmorillonite is prepared by the following method: Montmorillonite, ammonia, and anhydrous ethanol were mixed to obtain a montmorillonite dispersion. Tetraethyl orthosilicate and ethanol were mixed, stirred, and then added to the montmorillonite dispersion. The mixture was stirred and reacted, then filtered and dried to obtain silica-composite montmorillonite. The silica-composite montmorillonite was mixed with water, and the system was adjusted to alkalinity. After heating, octadecyltrimethylammonium bromide solution was added, and the mixture was stirred and reacted. Finally, the mixture was washed and centrifuged to obtain modified montmorillonite.

[0010] By adopting the above technical solution, tetraethyl orthosilicate is uniformly hydrolyzed and condensed on the surface of montmorillonite sheets to form a dense and uniform silica graft layer. Active silanol groups are introduced, reducing the agglomeration and uneven grafting of silica. Then, under alkaline conditions, octadecyltrimethylammonium bromide is inserted between the montmorillonite layers. The resulting modified montmorillonite has good exfoliation and dispersibility, sufficient surface active sites, and excellent barrier properties. It can fully combine with composite sugarcane fiber, thereby jointly improving the aging resistance and stability of the asphalt system.

[0011] Preferably, the mass ratio of montmorillonite, tetraethyl orthosilicate and octadecyltrimethylammonium bromide is 1:5:(1.4-1.8).

[0012] By adopting the above technical solution, and optimizing the mass ratio of montmorillonite, tetraethyl orthosilicate, and octadecyltrimethylammonium bromide within the specified range, tetraethyl orthosilicate can fully cover the hydroxyl groups of the montmorillonite sheets, thereby achieving uniform and dense silica grafting. Furthermore, excessive tetraethyl orthosilicate will not lead to excessive free silica self-polymerization. Simultaneously, it ensures that octadecyltrimethylammonium bromide can fully insert into the interlayer space, maximizing the expansion of the interlayer spacing. The resulting modified montmorillonite exhibits good stability and can form stable chemical bonds with composite sugarcane fibers, further improving the overall aging resistance of the asphalt system.

[0013] Preferably, the composite sugarcane fiber comprises sugarcane fiber, a metal-organic framework, and sodium alginate.

[0014] By adopting the above technical solution, sugarcane fiber, as the substrate, has a natural three-dimensional network structure and a high aspect ratio, which can form a continuous fiber reinforcing network in asphalt, effectively disperse stress, inhibit low-temperature catalytic cracking, and improve the temperature change resistance and mechanical strength of asphalt. The metal-organic framework has a high specific surface area and porous structure, which can efficiently adsorb aging intermediates such as alkyl free radicals generated after asphalt aging, and form a synergistic effect with the physical barrier of modified montmorillonite, further improving the aging resistance of asphalt. Sodium alginate, as the coating modification layer, can introduce a large number of carboxyl and hydroxyl active groups, which can undergo dehydration condensation reaction with the silanol groups on the surface of montmorillonite to form covalent bonds, thereby further improving the stability of the filler components.

[0015] Preferably, the composite sugarcane fiber is prepared by the following method: Sugarcane fiber, N,N-dimethylformamide, and aminosulfonic acid were mixed, ground, and washed to obtain modified sugarcane fiber. Modified sugarcane fiber, zinc nitrate, 2-methylimidazole, and N,N-dimethylformamide were mixed, ground, centrifuged, and washed to obtain metal-organic framework composite sugarcane fiber. Metal-organic framework composite sugarcane fiber was mixed with water, and sodium alginate was added while stirring to obtain composite sugarcane fiber.

[0016] By adopting the above technical solution, firstly, aminosulfonic acid is mixed and ground with sugarcane fiber to introduce active groups such as sulfonic acid groups and amino groups, thereby improving the surface reactivity of sugarcane fiber. Then, a metal-organic framework is synthesized in situ using a solid-phase grinding method. The surface active groups of modified sugarcane fiber combine with zinc ions and 2-methylimidazole to achieve in situ uniform growth of the metal-organic framework on the surface of sugarcane fiber. Finally, a sodium alginate solution is used for coating, which can further improve the compatibility between fiber and asphalt and introduce active groups to provide sites for chemical bonding with modified montmorillonite, thereby improving the stability of the prepared filler component.

[0017] Preferably, when preparing the metal-organic framework composite sugarcane fiber, the mass ratio of sugarcane fiber, zinc nitrate and 2-methylimidazole is (0.4-0.6):1:6.

[0018] By adopting the above technical solution, and optimizing the mass ratio of sugarcane fiber, zinc nitrate and 2-methylimidazole within the above range, the sugarcane fiber can enhance sufficient nucleation sites, thereby enabling the metal-organic framework to grow in situ on the surface of the sugarcane fiber. The prepared metal-organic framework composite sugarcane fiber has good stability.

[0019] Preferably, the mass ratio of the metal-organic framework composite sugarcane fiber to sodium alginate is 1:(0.8-1.2).

[0020] By adopting the above technical solution, the mass ratio between metal-organic framework composite sugarcane fiber and sodium alginate is preferably within the above range. Sodium alginate can form a uniform and complete coating layer on the surface of metal-organic framework composite sugarcane fiber, introduce sufficient carboxyl and hydroxyl active groups on the surface of the fiber, provide active sites, be uniformly dispersed in the system, and form a stable chemical bond with modified montmorillonite.

[0021] Secondly, this application provides a method for preparing low-grade road asphalt, employing the following technical solution: A method for preparing low-grade road asphalt includes the following steps: The asphalt matrix is ​​placed in a reaction vessel, heated and stirred, then filler components are added and stirring continues, then compatibilizer is added and stirring continues, then the temperature is lowered and vulcanizing agent and stabilizer are added under stirring conditions, stirred, heated and allowed to stand to obtain low-grade road asphalt.

[0022] In summary, this application includes at least one of the following beneficial technical effects: Through the synergistic combination of vulcanizing agent crosslinking network, modified montmorillonite nano barrier and composite sugarcane fiber three-dimensional network, multiple enhancements of physical barrier, free radical capture and mechanical reinforcement are achieved, effectively taking into account the high temperature strength, low temperature crack resistance and long-term aging resistance of low grade asphalt. Modified montmorillonite was modified by silica grafting and organic intercalation. The surface-active silanol groups can form chemical bonds with the composite sugarcane fiber, while expanding the interlayer spacing to promote nano-exfoliation and dispersion, and strengthening the interfacial bonding and synergistic enhancement effect between the two fillers. The composite sugarcane fiber is loaded with a metal-organic framework in situ and coated with sodium alginate. The metal-organic framework efficiently captures aging free radicals and forms a dual anti-aging mechanism with the physical barrier of montmorillonite. The active groups introduced by sodium alginate further enhance the bonding stability between the filler components. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the embodiments: Raw material description: All raw materials in the examples are commercially available; among them, the vulcanizing agent is sulfur powder, the compatibilizer is aromatic oil, and the stabilizer is zinc stearate (CAS No.: 557-05-1). Example 1

[0024] Preparation of modified montmorillonite: 6.76 g of montmorillonite (CAS No.: 1318-93-0), 17 g of ammonia water, and 350 g of anhydrous ethanol were mixed to obtain a montmorillonite dispersion. 33.78 g of tetraethyl orthosilicate (CAS No.: 78-10-4) and 65 g of anhydrous ethanol were mixed and then added to the montmorillonite dispersion. After standing for 10 min, the mixture was magnetically stirred for hydrolysis for 6 h. The mixture was then filtered and dried at 50 °C for 16 h to obtain silica-composite montmorillonite. The silica-composite montmorillonite prepared above was then mixed with 300 g of... The mixture was mixed with deionized water and ultrasonically dispersed for 30 min. Then, sodium hydroxide solution was added to adjust the pH of the system to 12 to obtain a silica-composite montmorillonite suspension. 9.46 g of octadecyltrimethylammonium bromide (CAS No.: 1120-02-1) was mixed with 100 g of deionized water and added to the silica-composite montmorillonite suspension. The mixture was stirred at 600 rpm for 3 h. After the reaction, the mixture was repeatedly washed with a 50% ethanol solution. After washing, the mixture was filtered and dried at 60 °C for 16 h to obtain modified montmorillonite.

[0025] Preparation of composite sugarcane fiber: Sugarcane bagasse was soaked in a 5% sodium hydroxide solution and treated in an oil bath at 80°C for 4 hours. After washing with deionized water, it was soaked in a 5% hydrochloric acid solution for 5 hours, and finally soaked in a 1.2% hydrogen peroxide solution and treated in an oil bath at 80°C for 4 hours. After washing until neutral, it was freeze-dried in a freeze-drying oven at -18°C for 12 hours to obtain sugarcane fiber. 5.41 g of sugarcane fiber, 60 g of N,N-dimethylformamide (CAS No.: 68-12-2), and 10 g of aminosulfonic acid (CAS No.: 5329-14-6) were mixed and added to a ball mill jar. Zirconia balls were then added to the ball mill jar, and the mixture was ball-milled at 350 rpm for 4 hours. After ball milling, it was washed with deionized water to obtain modified sugarcane fiber. The modified sugarcane fiber prepared above was then mixed with 100 g of N,N-dimethylformamide. N,N-dimethylformamide, 13.51 g of zinc nitrate, and 81.08 g of 2-methylimidazole (CAS No.: 693-98-1) were added to a ball mill jar and ball-milled at 350 rpm for 4 h. After ball milling, the mixture was centrifuged at 8000 rpm for 10 min to remove the supernatant. The mixture was then washed three times alternately with N,N-dimethylformamide and methanol and dried at 60 °C for 20 h to obtain metal-organic framework composite sugarcane fiber. 8.33 g of the metal-organic framework composite fiber was mixed with 500 g of deionized water, sonicated for 10 min, and magnetically stirred for 30 min. Then, the mixture was stirred at 900 rpm at 25 °C while stirring, and 6.67 g of sodium alginate (CAS No.: 9005-38-3) was added. The mixture was stirred for another 2.5 h and then dried at 40 °C for 18 h to obtain composite sugarcane fiber.

[0026] Preparation of filler components: 7.69g of composite sugarcane fiber was mixed with 12.31g of modified montmorillonite and added to a 50% ethanol aqueous solution. The pH of the system was adjusted to 8, and the mixture was stirred at 65℃ for 90min. The mixture was then filtered, dried in a 60℃ oven for 12h, and ground to obtain the filler component.

[0027] Preparation of low-grade road asphalt: Place 90g of asphalt matrix in a sealed reactor, heat to 135℃, and stir at a constant temperature until the matrix asphalt is completely dissolved. Then heat to 150℃, stir at 4000rpm, and add 9g of filler component. Continue stirring for 30min, then add 2g of compatibilizer and continue stirring for 15min. Then cool to 140℃, and add 0.2g of vulcanizing agent and 0.1g of stabilizer at 800rpm. Stir for 30min, and finally let stand in an oven at 140℃ for 2h to obtain low-grade road asphalt. Example 2

[0028] Preparation of modified montmorillonite: 6.41 g of montmorillonite, 17 g of ammonia, and 350 g of anhydrous ethanol were mixed to obtain a montmorillonite dispersion. 32.05 g of tetraethyl orthosilicate and 65 g of anhydrous ethanol were mixed and added to the montmorillonite dispersion. After standing for 10 min, the mixture was magnetically stirred for hydrolysis for 6 h. The mixture was then filtered and dried at 50 °C for 16 h to obtain silica composite montmorillonite. The silica composite montmorillonite prepared above was mixed with 300 g of deionized water and ultrasonically dispersed for 30 min. Sodium hydroxide solution was added to adjust the pH of the system to 12 to obtain a silica composite montmorillonite suspension. 11.54 g of octadecyltrimethylammonium bromide and 100 g of deionized water were mixed and added to the silica composite montmorillonite suspension. The mixture was stirred at 600 rpm for 3 h. After the reaction, the mixture was repeatedly washed with a 50% ethanol solution. After washing, the mixture was filtered and dried at 60 °C for 16 h to obtain modified montmorillonite.

[0029] Preparation of composite sugarcane fiber: Sugarcane bagasse was soaked in a 5% sodium hydroxide solution and treated in an oil bath at 80°C for 4 hours. After washing with deionized water, it was soaked in a 5% hydrochloric acid solution for 5 hours, and finally soaked in a 1.2% hydrogen peroxide solution and treated in an oil bath at 80°C for 4 hours. After washing until neutral, it was freeze-dried in a freeze-drying oven at -18°C for 12 hours to obtain sugarcane fiber. 7.89 g of sugarcane fiber, 60 g of N,N-dimethylformamide, and 10 g of aminosulfonic acid were mixed and added to a ball mill jar. Zirconia balls were then added to the ball mill jar, and the mixture was ball-milled at 350 rpm for 4 hours. After ball milling, it was washed with deionized water to obtain modified sugarcane fiber. The modified sugarcane fiber prepared above was then mixed with 100 g of N,N-dimethylformamide and 100 g of N,N-dimethylformamide. N-Dimethylformamide, 13.16 g of zinc nitrate, and 78.95 g of 2-methylimidazole were added to a ball mill jar and ball-milled at 350 rpm for 4 h. After ball milling, the mixture was centrifuged at 8000 rpm for 10 min to remove the supernatant. The mixture was then washed three times alternately with N,N-dimethylformamide and methanol and dried at 60 °C for 20 h to obtain metal-organic framework composite sugarcane fiber. 6.82 g of the metal-organic framework composite fiber was mixed with 500 g of deionized water, sonicated for 10 min, and magnetically stirred for 30 min. Then, the mixture was stirred at 900 rpm at 25 °C while stirring was continued. 8.18 g of sodium alginate was added, and stirring was continued for 2.5 h. Finally, the mixture was dried at 40 °C for 18 h to obtain composite sugarcane fiber.

[0030] Preparation of filler components: 7.14g of composite sugarcane fiber was mixed with 12.86g of modified montmorillonite and added to a 50% ethanol aqueous solution. The pH of the system was adjusted to 8, and the mixture was stirred at 65℃ for 90min. The mixture was then filtered, dried in a 60℃ oven for 12h, and ground to obtain the filler component.

[0031] Preparation of low-grade road asphalt: 110g of asphalt matrix was placed in a sealed reactor and heated to 135℃. The mixture was stirred at a constant temperature until the matrix asphalt was completely dissolved. Then, the temperature was raised to 150℃ and stirred at 4000 rpm. 13g of filler component was added and stirred for 30 minutes. Then, 8g of compatibilizer was added and stirred for 15 minutes. The temperature was then lowered to 140℃ and 0.5g of vulcanizing agent and 0.5g of stabilizer were added at 800 rpm and stirred for 30 minutes. Finally, the mixture was allowed to stand in an oven at 140℃ for 2 hours to obtain low-grade road asphalt. Example 3

[0032] Preparation of modified montmorillonite: 6.58 g of montmorillonite, 17 g of ammonia, and 350 g of anhydrous ethanol were mixed to obtain a montmorillonite dispersion. 32.89 g of tetraethyl orthosilicate and 65 g of anhydrous ethanol were mixed and added to the montmorillonite dispersion. After standing for 10 min, the mixture was magnetically stirred for hydrolysis for 6 h. The mixture was then filtered and dried at 50 °C for 16 h to obtain silica composite montmorillonite. The silica composite montmorillonite prepared above was mixed with 300 g of deionized water and ultrasonically dispersed for 30 min. Sodium hydroxide solution was added to adjust the pH of the system to 12 to obtain a silica composite montmorillonite suspension. 10.53 g of octadecyltrimethylammonium bromide and 100 g of deionized water were mixed and added to the silica composite montmorillonite suspension. The mixture was stirred at 600 rpm for 3 h. After the reaction, the mixture was repeatedly washed with a 50% ethanol solution. After washing, the mixture was filtered and dried at 60 °C for 16 h to obtain modified montmorillonite.

[0033] Preparation of composite sugarcane fiber: Sugarcane bagasse was soaked in a 5% sodium hydroxide solution and treated in an oil bath at 80°C for 4 hours. After washing with deionized water, it was soaked in a 5% hydrochloric acid solution for 5 hours, and finally soaked in a 1.2% hydrogen peroxide solution and treated in an oil bath at 80°C for 4 hours. After washing until neutral, it was freeze-dried in a freeze-drying oven at -18°C for 12 hours to obtain sugarcane fiber. 6.67g of sugarcane fiber, 60g of N,N-dimethylformamide, and 10g of aminosulfonic acid were mixed and added to a ball mill jar. Zirconia balls were then added to the ball mill jar, and the mixture was ball-milled at 350 rpm for 4 hours. After ball milling, it was washed with deionized water to obtain modified sugarcane fiber. The modified sugarcane fiber prepared above was then combined with 100g of... N,N-dimethylformamide, 13.33 g of zinc nitrate, and 80 g of 2-methylimidazole were added to a ball mill jar and ball-milled at 350 rpm for 4 h. After ball milling, the mixture was centrifuged at 8000 rpm for 10 min to remove the supernatant. The mixture was then washed three times alternately with N,N-dimethylformamide and methanol and dried at 60 °C for 20 h to obtain metal-organic framework composite sugarcane fiber. 7.5 g of the metal-organic framework composite fiber was mixed with 500 g of deionized water, sonicated for 10 min, and magnetically stirred for 30 min. Then, the mixture was stirred at 900 rpm at 25 °C while stirring was continued. 7.5 g of sodium alginate was added, and stirring was continued for 2.5 h. Finally, the mixture was dried at 40 °C for 18 h to obtain composite sugarcane fiber.

[0034] Preparation of filler components: 7.41g of composite sugarcane fiber was mixed with 12.59g of modified montmorillonite and added to a 50% (v / v) ethanol aqueous solution. The pH of the system was adjusted to 8, and the mixture was stirred at 65℃ for 90 min. The mixture was then filtered, dried in a 60℃ bellows for 12 h, and ground to obtain the filler component.

[0035] Preparation of low-grade road asphalt: 100g of asphalt matrix was placed in a sealed reactor and heated to 135℃. The mixture was stirred at a constant temperature until the matrix asphalt was completely dissolved. Then, the temperature was raised to 150℃ and stirred at 4000 rpm. 11g of filler component was added and stirred for 30 minutes. Then, 5g of compatibilizer was added and stirred for 15 minutes. The temperature was then lowered to 140℃ and 0.5g of vulcanizing agent and 0.3g of stabilizer were added at 800 rpm and stirred for 30 minutes. Finally, the mixture was allowed to stand in an oven at 140℃ for 2 hours to obtain low-grade road asphalt. Example 4

[0036] Example 4 is based on Example 3. The difference between Example 4 and Example 3 is that in Example 4, when preparing modified montmorillonite, the amount of montmorillonite used is 7.04g, the amount of tetraethyl orthosilicate used is 35.21g, and the amount of octadecyltrimethylammonium bromide used is 7.75g. Example 5

[0037] Example 5 is based on Example 3. The difference between Example 5 and Example 3 is that in Example 5, when preparing modified montmorillonite, the amount of montmorillonite used is 6.17g, the amount of tetraethyl orthosilicate used is 30.87g, and the amount of octadecyltrimethylammonium bromide used is 12.96g. Example 6

[0038] Example 6 is based on Example 3. The difference between Example 6 and Example 3 is that in Example 6, octadecyltrimethylammonium bromide was not used for treatment when preparing modified montmorillonite. Example 7

[0039] Example 7 is based on Example 3. The difference between Example 7 and Example 3 is that tetraethyl orthosilicate was not used in the preparation of modified montmorillonite in Example 7. Example 8

[0040] Example 8 is based on Example 3. The difference between Example 8 and Example 3 is that in the preparation process of the metal-organic framework composite sugarcane fiber in Example 8, the amount of sugarcane fiber used is 3.45g, the amount of zinc nitrate used is 13.79g, and the amount of 2-methylimidazole used is 82.76g. Example 9

[0041] Example 9 is based on Example 3. The difference between Example 9 and Example 3 is that in the preparation process of the metal-organic framework composite sugarcane fiber in Example 9, the amount of sugarcane fiber used is 7.28g, the amount of zinc nitrate used is 13.25g, and the amount of 2-methylimidazole used is 79.47g. Example 10

[0042] Example 10 is based on Example 3. The difference between Example 10 and Example 3 is that in Example 10, when preparing the composite sugarcane fiber, the amount of metal-organic framework composite sugarcane fiber used is 10g and the amount of sodium alginate used is 5g. Example 11

[0043] Example 11 is based on Example 3. The difference between Example 11 and Example 3 is that in Example 11, when preparing the composite sugarcane fiber, the amount of metal-organic framework composite sugarcane fiber used is 6g and the amount of sodium alginate used is 9g. Example 12

[0044] Example 12 is based on Example 3. The difference between Example 12 and Example 3 is that in Example 12, when preparing composite sugarcane fiber, the metal-organic framework composite sugarcane fiber is replaced with ordinary sugarcane fiber. Example 13

[0045] Example 13 is based on Example 3. The difference between Example 13 and Example 3 is that in Example 13, the amount of composite sugarcane fiber used in preparing the filler components is 8.33g and the amount of modified montmorillonite used is 11.67g. Example 14

[0046] Example 14 is based on Example 3. The difference between Example 14 and Example 3 is that in Example 14, the amount of composite sugarcane fiber used in preparing the filler components is 6.67g and the amount of modified montmorillonite used is 13.33g. Example 15

[0047] Example 15 is based on Example 3. The difference between Example 15 and Example 3 is that in Example 15, only the composite sugarcane fiber and modified montmorillonite are physically mixed when preparing the filler components.

[0048] Comparative Example 1 Comparative Example 1 is based on Example 3. In Comparative Example 1, when preparing the filler components, the composite sugarcane fiber was replaced with an equal amount of ordinary sugarcane fiber.

[0049] Comparative Example 2 Comparative Example 2 is based on Example 3. In Comparative Example 2, the modified montmorillonite was replaced with an equal amount of ordinary montmorillonite when preparing the filler components.

[0050] Comparative Example 3 Comparative Example 3 is based on Example 3, except that the filler component in Comparative Example 3 is replaced with an equal amount of modified montmorillonite instead of composite sugarcane fiber.

[0051] Comparative Example 4 Comparative Example 4 is based on Example 3, except that the filler component in Comparative Example 4 is modified montmorillonite replaced with an equal amount of composite sugarcane fiber.

[0052] Performance testing The following performance tests were performed on the samples of Examples 1-15 and Comparative Examples 1-4: (1) Needle penetration Using GB / T 4509-2010 as the testing reference, the penetration of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were then recorded in Table 1.

[0053] (2) Thermo-oxidative aging test Using GB / T 5304-2001 as the testing reference, the aging resistance of the samples was tested. Each sample was tested three times, and the average value was taken. The test results were recorded in Table 1.

[0054] (3) Softening point test Using GB / T 4507-2014 as the testing reference, the softening point of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were recorded in Table 1.

[0055] Table 1 Performance test results of Examples 1-15 and Comparative Examples 1-4

[0056] As shown in Table 1, the penetration at 25°C in Examples 1-3 all meet the national standard range for No. 50 low-grade road asphalt. The penetration retention rate after thermo-oxidative aging is 82% or higher, and the softening point is 55°C or higher. This indicates that the low-grade road asphalt prepared in this application has good mechanical properties and aging resistance.

[0057] The montmorillonite, tetraethyl orthosilicate, and octadecyltrimethylammonium bromide in Examples 4 and 5 are not within the scope defined in this application. When octadecyltrimethylammonium bromide is insufficient, it is difficult to achieve interlayer cation exchange, resulting in insufficient interlayer expansion of montmorillonite, making it difficult to peel and disperse in the asphalt and causing agglomeration, which affects the overall stability of the system. When octadecyltrimethylammonium bromide is excessive, the excess octadecyltrimethylammonium bromide is difficult to insert into the interlayer and is free in the system, and it migrates in the system, destroying the overall stability of the asphalt. Therefore, the performance of Examples 4 and 5 both decreases.

[0058] In Example 6, the montmorillonite was not treated with octadecyltrimethylammonium bromide. The untreated montmorillonite had small interlayer spacing, agglomerated in the system, had poor compatibility with the asphalt matrix, weak interfacial bonding, and all its overall performance was reduced.

[0059] In the preparation of modified montmorillonite in Example 7, tetraethyl orthosilicate was not used. Montmorillonite has few active sites on its surface, making it difficult to form stable chemical bonds with composite sugarcane fibers. The filler migrates and separates in the asphalt system, failing to form a continuous barrier network, resulting in a decline in overall performance.

[0060] In Examples 8 and 9, the mass ratios of sugarcane fiber, zinc nitrate, and 2-methylimidazole are not within the range specified in this application. When there is insufficient sugarcane fiber, there are not enough active sites on the surface that can be used for the nucleation of metal-organic frameworks, making it difficult for the metal-organic framework to grow uniformly in situ on the confined surface, resulting in agglomeration and difficulty in forming a continuous and stable three-dimensional reinforcing network in the asphalt. When there is excessive sugarcane fiber, there are too many surface active sites, resulting in excessively small metal-organic framework grains, insufficient crystallinity, incomplete development of porous structure, and difficulty in uniform dispersion in the system, leading to decreased stability. Therefore, the performance of Examples 8 and 9 is reduced.

[0061] In Examples 10 and 11, the mass ratio between the metal-organic framework composite sugarcane fiber and sodium alginate was not within the range specified in this application. When sodium alginate was insufficient, it was difficult to form a complete and uniform coating layer on the surface of the metal-organic framework composite sugarcane fiber, making it difficult to effectively fix the metal-organic framework. Furthermore, the number of active clusters introduced on the fiber surface was insufficient, and the chemical bonding network between the fillers was incomplete. When sodium alginate was excessive, an excessively thick coating layer was formed on the fiber surface, blocking the channels of the metal-organic framework, making it difficult to adsorb and capture aging free radicals, and reducing the compatibility with the asphalt matrix, leading to phase separation and damaging the stability of the asphalt. Therefore, the performance of Examples 10 and 11 was reduced.

[0062] In Example 12, when preparing composite sugarcane, the metal-organic framework composite fiber was replaced with ordinary sugarcane fiber. Ordinary sugarcane fiber was not activated and coated with the metal-organic framework, so it could not capture free radicals. It was difficult to form a complete aging-resistant closed-loop system by relying solely on the physical barrier of modified montmorillonite, and it was also difficult to form chemical bonds with modified montmorillonite, so it was difficult to play a synergistic role in improving aging resistance.

[0063] In Examples 13 and 14, the mass ratio between composite sugarcane fiber and modified montmorillonite during the preparation of filler components was not within the range specified in this application. When the modified montmorillonite was insufficient, it was difficult to form a continuous barrier network in the asphalt system, resulting in decreased aging resistance and reduced reinforcement effect on the asphalt. When the modified montmorillonite was excessive, lamellar stacking and agglomeration occurred in the system, forming a large number of rigid particles, which reduced the plasticity of the asphalt, caused severe embrittlement, and affected the overall stability of the system.

[0064] In Example 15, when preparing the filler components, only the composite sugarcane and modified montmorillonite were physically mixed. The two fillers that were only physically mixed did not have chemical bonds between them. During long-term service, sedimentation and phase separation occurred, making it difficult to form a continuous network. In addition, the filler had poor dispersibility and decreased stability.

[0065] In Comparative Example 1, the composite sugarcane fiber in the filler component was replaced with ordinary unmodified sugarcane fiber. The fiber surface lacked the loading of the metal-organic skeleton and lost its ability to capture free radicals. Relying solely on the physical barrier of montmorillonite, it was difficult to cope with the continuous aging reaction inside the asphalt, resulting in decreased stability.

[0066] In Comparative Example 2, the modified montmorillonite in the filler component was replaced with ordinary montmorillonite. The unmodified montmorillonite had small interlayer spacing, agglomeration, and difficulty in forming an effective physical barrier. It was also difficult to establish a continuous three-dimensional functional network with the composite sugarcane fiber, resulting in a decline in performance.

[0067] The filler component of Comparative Example 3 consisted only of modified montmorillonite, and the filler component of Comparative Example 4 consisted only of composite sugarcane fiber. It is difficult to construct a continuous three-dimensional network structure with a single filler component, which makes it difficult to synergistically improve the aging resistance of the system and reduces the stability of the system.

[0068] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A low-grade road asphalt, characterized in that: The components include the following parts by mass: The composition includes 90-110 parts base asphalt, 0.2-0.5 parts vulcanizing agent, 9-13 parts filler components, 2-8 parts compatibilizer, and 0.1-0.5 parts stabilizer. The filler components include composite sugarcane fiber and modified montmorillonite.

2. The low-grade road asphalt according to claim 1, characterized in that: The modified montmorillonite comprises montmorillonite, silica, and octadecyltrimethylammonium bromide.

3. The low-grade road asphalt according to claim 2, characterized in that: The modified montmorillonite was prepared using the following method: Montmorillonite, ammonia, and anhydrous ethanol were mixed to obtain a montmorillonite dispersion. Tetraethyl orthosilicate and ethanol were mixed, stirred, and then added to the montmorillonite dispersion. The mixture was stirred and reacted, then filtered and dried to obtain silica-composite montmorillonite. The silica-composite montmorillonite was mixed with water, and the system was adjusted to alkalinity. After heating, octadecyltrimethylammonium bromide solution was added, and the mixture was stirred and reacted. Finally, the mixture was washed and centrifuged to obtain modified montmorillonite.

4. The low-grade road asphalt according to claim 3, characterized in that: The mass ratio of montmorillonite, tetraethyl orthosilicate and octadecyltrimethylammonium bromide is 1:5:(1.4-1.8).

5. The low-grade road asphalt according to claim 1, characterized in that: The composite sugarcane fiber comprises sugarcane fiber, a metal-organic framework, and sodium alginate.

6. The low-grade road asphalt according to claim 5, characterized in that: The composite sugarcane fiber is prepared by the following method: Sugarcane fiber, N,N-dimethylformamide, and aminosulfonic acid were mixed, ground, and washed to obtain modified sugarcane fiber. Modified sugarcane fiber, zinc nitrate, 2-methylimidazole, and N,N-dimethylformamide were mixed, ground, centrifuged, and washed to obtain metal-organic framework composite sugarcane fiber. Metal-organic framework composite sugarcane fiber was mixed with water, and sodium alginate was added while stirring to obtain composite sugarcane fiber.

7. A low-grade road asphalt according to claim 6, characterized in that: In the preparation of the metal-organic framework composite sugarcane fiber, the mass ratio of sugarcane fiber, zinc nitrate and 2-methylimidazole is (0.4-0.6):1:

6.

8. A low-grade road asphalt according to claim 6, characterized in that: The mass ratio of the metal-organic framework composite sugarcane fiber to sodium alginate is 1:(0.8-1.2).

9. A low-grade road asphalt according to claim 1, characterized in that: The mass ratio of the composite sugarcane fiber to the modified montmorillonite is 1:(1.6-1.8).

10. A method for preparing low-grade road asphalt according to any one of claims 1-9, characterized in that: Includes the following steps: The asphalt matrix is ​​placed in a reaction vessel, heated and stirred, then filler components are added and stirring continues, then compatibilizer is added and stirring continues, then the temperature is lowered and vulcanizing agent and stabilizer are added under stirring conditions, stirred, heated and allowed to stand to obtain low-grade road asphalt.

Images