A wear-resistant and crack-resistant elastomer-modified recycled asphalt and its preparation method

Abstract

This invention discloses a wear-resistant and crack-resistant elastomer-modified recycled asphalt and its preparation method, belonging to the field of asphalt recycling technology. The wear-resistant and crack-resistant elastomer-modified recycled asphalt comprises the following raw materials in parts by weight: 90-110 parts aged asphalt, 5-8 parts modified recycling agent, 1-3 parts modified reinforcing agent, 4-8 parts composite elastomer, and 0.1-0.3 parts catalyst. The wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared by this invention exhibits good low-temperature flexibility, elastic recovery, self-healing ability, and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of asphalt recycling technology, specifically to a wear-resistant and crack-resistant elastomer-modified recycled asphalt and its preparation method. Background Technology

[0002] Asphalt, a key material widely used in road engineering, undergoes aging and performance degradation during use due to the combined effects of light, heat, oxygen, and traffic loads. This degradation is mainly manifested in component migration, reduction of aromatic hydrocarbons, and increase in resins and asphaltenes, leading to pavement embrittlement, cracking, and decreased durability. Recycling waste asphalt pavement materials is an important way to conserve resources and protect the environment. However, traditional recycling technologies mainly focus on restoring the penetration and softening point of aged asphalt, making it difficult to simultaneously improve the low-temperature crack resistance and high-temperature rutting resistance of recycled asphalt. While existing elastomer-modified asphalt can improve some mechanical properties, it generally suffers from poor compatibility between the elastomer and aged asphalt, insufficient toughness after recycling, and poor wear resistance. In recent years, the introduction of functionalized regenerators containing dynamic bonds has become a research hotspot, but most systems still rely on a single chemical repair mechanism, with limited ability to rebuild polar components and reconstruct cross-linked networks in aged asphalt. Furthermore, nano-reinforcing materials tend to agglomerate in asphalt, making it difficult to fully utilize their surface effects and small size advantages.

[0003] Chinese invention patent CN113214660A discloses a waterproof and wear-resistant recycled asphalt and its preparation method. The recycled asphalt mainly consists of recycled asphalt waste, a regenerating agent, a stabilizer, an emulsifier, a high-density polyethylene composite, 3-aminopropyltriethoxysilane, and a corn stalk composite. The recycled asphalt prepared by this invention exhibits good wear resistance and hydrophobic properties, demonstrating good practicality; however, its crack resistance still needs improvement.

[0004] Therefore, developing a modified recycled asphalt that combines regeneration, wear resistance, and crack resistance is of great significance for improving the recycling of aged asphalt. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a wear-resistant and crack-resistant elastomer-modified recycled asphalt and its preparation method.

[0006] A wear-resistant and crack-resistant elastomer-modified recycled asphalt comprises the following raw materials in parts by weight: 90-110 parts aged asphalt, 5-8 parts modified recycling agent, 1-3 parts modified reinforcing agent, 4-8 parts composite elastomer, and 0.1-0.3 parts catalyst; The modified regenerator is epoxidized soybean oil modified with 3,3'-dithiodipropionic acid.

[0007] The modified reinforcing agent is prepared by the following method: Nano-silicon carbide was uniformly dispersed in an alkaline buffer solution, and dopamine hydrochloride and L-cysteine ​​were added to synthesize a modified reinforcing agent in situ.

[0008] The preparation method of the 3,3'-dithiodipropionic acid modified epoxidized soybean oil is as follows: 3,3'-Dithiodipropionic acid was prepared by reacting epoxidized soybean oil with tetrabutylammonium bromide. The mass ratio of 3,3'-dithiodipropionic acid to epoxidized soybean oil was (1-1.2):5.

[0009] The mass ratio of nano-silicon carbide, dopamine hydrochloride, and L-cysteine ​​is 10:2:1.

[0010] The alkaline buffer solution is Tris-HCl buffer solution.

[0011] The composite elastomer is made by blending styrene-butadiene-styrene block copolymer and rubber powder at a mass ratio of 1:(3-4).

[0012] The catalyst is one of 2-methylimidazole and N,N-dimethylbenzylamine.

[0013] A method for preparing wear-resistant and crack-resistant elastomer-modified recycled asphalt includes the following steps: (1) Weigh out the following by weight: 90-110 parts aged asphalt, 5-8 parts modified recycling agent, 1-3 parts modified reinforcing agent, 4-8 parts composite elastomer, and 0.1-0.3 parts catalyst; (2) Heat and melt aged asphalt, add a mixture of modifier and regenerator to obtain recycled asphalt premix; add composite elastomer and shear at high speed, then add catalyst for constant temperature development and static degassing to obtain wear-resistant and crack-resistant elastomer modified recycled asphalt.

[0014] In step (2), the temperature at which the aged asphalt is heated and melted is 140-160℃.

[0015] In step (2), the constant temperature development time is 100-120 min and the development temperature is 150-170℃.

[0016] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: This invention utilizes the synergistic effect of modified regenerators, modified reinforcing agents, and composite elastomers to prepare modified recycled asphalt that possesses excellent low-temperature flexibility, elastic recovery, and self-healing ability. The modified regenerator restores the lightweight components and molecular mobility of aged asphalt, the modified reinforcing agent improves interfacial bonding and deformation resistance, and the composite elastomer constructs an elastic support network, thereby significantly improving penetration at 25°C, ductility at 5°C, elastic recovery rate, healing rate, and wear resistance. Attached Figure Description

[0017] Figure 1 Fourier transform infrared spectrum of the modified regenerator prepared in Example 1; Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum of the modified regenerator prepared in Example 1; Figure 3 A scanning electron microscope image of the modified reinforcing agent prepared in Example 4; Figure 4 Fluorescence micrograph of the wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared in Example 5; Figure 5 Fluorescence micrograph of the wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared in Comparative Example 3; Figure 6 Fluorescence micrograph of the wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared in Comparative Example 4. Detailed Implementation

[0018] Example 1: Preparation of Modified Regenerant 100g of epoxidized soybean oil was added to the reaction flask, and the temperature was raised to 105℃ and stirred for 30min. Then the temperature was raised to 115℃, and 20g of 3,3'-dithiodipropionic acid was added in batches (5 batches, 5min intervals between batches). Then 0.3g of tetrabutylammonium bromide was added, and the temperature was raised to 120℃. After reacting for 3h under stirring at 300r / min, the temperature was lowered to 70℃, filtered through a 200-mesh stainless steel mesh, and degassed under vacuum at 70℃ and -0.08MPa for 30min to obtain the modified regenerator.

[0019] Figure 1 The Fourier transform infrared spectrum of the modified regenerator prepared in Example 1 is shown above. As can be seen from the spectrum, at 3410 cm⁻¹... -1 A relatively broad absorption peak appears nearby, mainly attributed to the stretching vibration of hydroxyl groups; 2924 cm⁻¹ -1 2854cm -1 and 723cm -1 The strong absorption peaks nearby are due to the stretching vibrations of long-chain aliphatic -CH2- and -CH3- molecules, indicating that the product retains the flexible long-chain fatty acid structure of epoxidized soybean oil; 1740 cm⁻¹ -1 The strong absorption peaks nearby are attributed to the C=O stretching vibration of the ester group, mainly originating from the glycerol ester structure in epoxidized soybean oil; 1460 cm⁻¹ -1 and 1378cm -1 The nearby absorption peak corresponds to the bending vibrations of the methylene and methyl groups; 1245 cm⁻¹ -1 1160cm -1 1105cm -1 and 1030cm -1The nearby absorption peaks are mainly attributed to the stretching vibrations of COC and CO, further indicating the presence of ester bonds, ether bonds, and alcohol hydroxyl groups formed after ring opening in the system; 845 cm⁻¹ -1 Weak epoxide characteristic absorption peaks can be observed nearby, indicating that the epoxidized soybean oil still retains some of the epoxide structure after modification.

[0020] Figure 2 The XPS diagram of the modified regenerator prepared in Example 1 shows that the sample mainly contains C, O, and S elemental signals. The strong peak around 284.8 eV is attributed to C 1s, which mainly originates from the long-chain aliphatic structure of epoxidized soybean oil, the ester group carbon, and the carbon skeleton formed after the carboxyl-epoxy ring opening. The peak around 532 eV is attributed to O 1s, indicating that the product contains oxygen-containing functional groups such as ester groups, hydroxyl groups, ether bonds, and residual epoxy groups. The weak peaks around 227 eV and 164 eV can be attributed to S 2s and S 2p signals, respectively, indicating that the sulfur-containing structure in 3,3'-dithiodipropionic acid has been introduced into the modified regenerator.

[0021] Example 2 Preparation of Modified Regenerant 100g of epoxidized soybean oil was added to the reaction flask, and the temperature was raised to 105℃ and stirred for 30min. Then the temperature was raised to 115℃, and 22g of 3,3'-dithiodipropionic acid was added in batches (5 batches, 5min intervals between batches). Then 0.3g of tetrabutylammonium bromide was added, and the temperature was raised to 120℃. After reacting for 3h under stirring at 300r / min, the temperature was lowered to 70℃, filtered through a 200-mesh stainless steel mesh, and degassed under vacuum at 70℃ and -0.08MPa for 30min to obtain the modified regenerator.

[0022] Example 3 Preparation of Modified Regenerant 100g of epoxidized soybean oil was added to the reaction flask, and the temperature was raised to 105℃ and stirred for 30min. Then the temperature was raised to 115℃, and 24g of 3,3'-dithiodipropionic acid was added in batches (5 batches, 5min intervals between batches). Then 0.3g of tetrabutylammonium bromide was added, and the temperature was raised to 120℃. After reacting for 3h under stirring at 300r / min, the temperature was lowered to 70℃, filtered through a 200-mesh stainless steel mesh, and degassed under vacuum at 70℃ and -0.08MPa for 30min to obtain the modified regenerator.

[0023] Example 4 Preparation of Modifying and Reinforcing Agent Weigh 1.0 g of nano-silicon carbide and add it to 80 mL of anhydrous ethanol. Under ice bath conditions, ultrasonically clean it with 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, and collect the precipitate. Then add it to 80 mL of deionized water and continue ultrasonic cleaning at 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, collect the precipitate, place it in a vacuum drying oven, and dry it at 60 ℃ and -0.08 MPa for 12 h. After grinding, the pretreated nano-silicon carbide is obtained.

[0024] Under ice bath conditions, 1.0 g of pretreated nano-silicon carbide was added to 100 mL of 20 mmol / L Tris-HCl buffer solution with pH=8.5, and ultrasonically dispersed at 300 W for 30 min, while controlling the system temperature to be no higher than 25 °C, to obtain a nano-silicon carbide suspension. Separately, 0.1 g of L-cystine was added to 8.5 mL of 0.1 mol / L sodium hydroxide solution and stirred at room temperature until dissolved to obtain an alkaline L-cystine solution. The alkaline L-cystine solution was slowly added dropwise to the nano-silicon carbide suspension, and the addition was completed in 5 min. The mixture was stirred for another 20 min, and the pH of the system was adjusted to 8.5 ± 0.1 using 0.5 M dilute hydrochloric acid. Subsequently, 0.2 g of dopamine hydrochloride was added, and after stirring and dissolving, the pH was adjusted to 8.5 ± 0.1 using 5 wt% sodium hydroxide solution. The mixture was stirred at room temperature in air for 24 h, centrifuged at 8000 r / min for 10 min, and the precipitate was collected. The precipitate was washed successively with deionized water and anhydrous ethanol until the pH of the supernatant was neutral. The mixture was filtered, vacuum dried at 60 °C for 12 h, ground, and passed through a 200 mesh sieve to obtain the modified reinforcing agent.

[0025] Figure 3 The image shows a scanning electron microscope (SEM) image of the modified reinforcing agent prepared in Example 4. As can be seen from the image, the modified reinforcing agent has a nanoparticle morphology with relatively rough particle surfaces. The particles are stacked together to form a multi-level rough structure. The rough surface morphology is beneficial to improving the interfacial interlocking and stress transfer capabilities in the asphalt system.

[0026] Example 5: Preparation of Wear-Resistant and Crack-Resistant Elastomer-Modified Recycled Asphalt (1) Weigh: 900g of aged asphalt, 50g of modified regenerator (prepared in Example 1), 10g of modified reinforcing agent (prepared in Example 4), 40g of composite elastomer (10g of styrene-butadiene-styrene block copolymer, 30g of rubber powder), and 1g of catalyst (2-methylimidazole); (2) Add the modified reinforcing agent to the modified regenerating agent and premix at 80°C and 600 rpm for 20 min to obtain a mixture of the modified reinforcing agent and the modified regenerating agent; heat the aged asphalt to 140°C to melt it, add the mixture of the modified reinforcing agent and the modified regenerating agent to the aged asphalt under stirring conditions, and shear at 2000 rpm for 30 min to obtain a recycled asphalt premix; raise the system temperature to 170°C, add the composite elastomer, and shear at 4500 rpm for 30 min; reduce the speed to 500 rpm, add the catalyst, stir and develop at 150°C for 120 min, then let it stand at 160°C for 30 min to degas, and cool to room temperature to obtain wear-resistant and crack-resistant elastomer modified recycled asphalt.

[0027] Example 6 Preparation of wear-resistant and crack-resistant elastomer-modified recycled asphalt (1) Weigh out: 1000g of aged asphalt, 65g of modified regenerator (prepared in Example 2), 20g of modified reinforcing agent (prepared in Example 4), 60g of composite elastomer (12g of styrene-butadiene-styrene block copolymer, 48g of rubber powder), and 2g of catalyst (2-methylimidazole); (2) Add the modified reinforcing agent to the modified regenerating agent and premix at 80°C and 600 rpm for 20 min to obtain a mixture of the modified reinforcing agent and the modified regenerating agent; heat the aged asphalt to 150°C to melt it, add the mixture of the modified reinforcing agent and the modified regenerating agent to the aged asphalt under stirring conditions, and shear at 2000 rpm for 30 min to obtain a recycled asphalt premix; heat the system to 170°C, add the composite elastomer, and shear at 4500 rpm for 30 min; reduce the speed to 500 rpm, add the catalyst, stir and develop at 160°C for 110 min, then let it stand at 160°C for 30 min to degas, and cool to room temperature to obtain wear-resistant and crack-resistant elastomer modified recycled asphalt.

[0028] Example 7 Preparation of wear-resistant and crack-resistant elastomer-modified recycled asphalt (1) Weigh out: 1100g of aged asphalt, 80g of modified regenerator (prepared in Example 3), 30g of modified reinforcing agent (prepared in Example 4), 80g of composite elastomer (16g of styrene-butadiene-styrene block copolymer, 64g of rubber powder), and 3g of catalyst (N,N-dimethylbenzylamine). (2) Add the modified reinforcing agent to the modified regenerating agent and premix at 80°C and 600 rpm for 20 min to obtain a mixture of the modified reinforcing agent and the modified regenerating agent; heat the aged asphalt to 160°C to melt it, add the mixture of the modified reinforcing agent and the modified regenerating agent to the aged asphalt under stirring conditions, and shear at 2000 rpm for 30 min to obtain a recycled asphalt premix; heat the system to 170°C, add the composite elastomer, and shear at 4500 rpm for 30 min; reduce the speed to 500 rpm, add the catalyst, stir and develop at 170°C for 100 min, then let it stand at 160°C for 30 min to degas, and cool to room temperature to obtain wear-resistant and crack-resistant elastomer modified recycled asphalt.

[0029] Comparative Example 1 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modified recycling agent is replaced with an equal weight of the modified recycling agent prepared by the following method: The preparation method of the modified regenerator is basically the same as that in Example 2, except that 3,3'-dithiodipropionic acid is replaced with an equal weight of 3,3'-thiodipropionic acid.

[0030] Comparative Example 2 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modified recycling agent is replaced with an equal weight of the modified recycling agent prepared by the following method: The preparation method of the modified regenerator is basically the same as that in Example 2, except that 3,3'-dithiodipropionic acid is replaced with an equal weight of adipic acid.

[0031] Comparative Example 3 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modified recycling agent is replaced with an equal weight of the modified recycling agent prepared by the following method: The preparation method of the modified regenerator is basically the same as that in Example 2, except that 3,3'-dithiodipropionic acid is replaced with an equal weight of 3-(methyldithio)-propionic acid.

[0032] Comparative Example 4 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer modified recycled asphalt are basically the same as those in Example 6. The difference is that the modified recycling agent is replaced with an equal weight of epoxidized soybean oil.

[0033] Comparative Example 5 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modified recycling agent is replaced with an equal weight of the modified recycling agent prepared by the following method: The preparation method of the modified regenerator is basically the same as that in Example 2, except that the amount of 3,3'-dithiodipropionic acid added is 10g.

[0034] Comparative Example 6 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modified recycling agent is replaced with an equal weight of the modified recycling agent prepared by the following method: The preparation method of the modified regenerator is basically the same as that in Example 2, except that the amount of 3,3'-dithiodipropionic acid added is 60g.

[0035] Comparative Example 7 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modifier is replaced with an equal weight of the modifier prepared by the following method: Weigh 1.0 g of nano-silicon carbide and add it to 80 mL of anhydrous ethanol. Under ice bath conditions, ultrasonically clean it with 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, and collect the precipitate. Then add it to 80 mL of deionized water and continue ultrasonic cleaning at 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, collect the precipitate, place it in a vacuum drying oven, and dry it at 60 ℃ and -0.08 MPa for 12 h. After grinding, the pretreated nano-silicon carbide is obtained.

[0036] Under ice bath conditions, 1.0 g of pretreated nano-silicon carbide was added to 100 mL of 20 mmol / L Tris-HCl buffer solution (pH=8.5) and ultrasonically dispersed for 30 min at 300 W, with the system temperature controlled not to exceed 25 °C, to obtain a nano-silicon carbide suspension. Then, 0.2 g of dopamine hydrochloride was added, stirred and dissolved, and the pH was adjusted to 8.5 ± 0.1 with 10 wt% sodium hydroxide solution. After stirring at room temperature in air for 24 h, the precipitate was centrifuged at 8000 r / min for 10 min, collected, and washed successively with deionized water and anhydrous ethanol until the pH of the supernatant was neutral. The precipitate was filtered, vacuum dried at 60 °C for 12 h, ground, and passed through a 200-mesh sieve to obtain the modified reinforcing agent.

[0037] Comparative Example 8 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modifier is replaced with an equal weight of the modifier prepared by the following method: Weigh 1.0 g of nano-silicon carbide and add it to 80 mL of anhydrous ethanol. Under ice bath conditions, ultrasonically clean it with 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, and collect the precipitate. Then add it to 80 mL of deionized water and continue ultrasonic cleaning at 300 W ultrasonic power for 30 min, centrifuge it at 8000 r / min for 10 min, collect the precipitate, place it in a vacuum drying oven, and dry it at 60 ℃ and -0.08 MPa for 12 h. After grinding, the pretreated nano-silicon carbide is obtained.

[0038] Under ice bath conditions, 1.0 g of pretreated nano-silicon carbide was added to deionized water and ultrasonically dispersed at 300 W for 30 min, while controlling the system temperature to be no higher than 25 °C, to obtain a nano-silicon carbide suspension. Separately, 0.1 g of L-cystine was added to 8.5 mL of 0.1 mol / L sodium hydroxide solution and stirred at room temperature until dissolved to obtain an alkaline L-cystine solution. The alkaline L-cystine solution was slowly added dropwise to the nano-silicon carbide suspension, and the addition was completed in 5 min. The mixture was stirred for another 20 min, and the pH of the system was adjusted to 8.5 ± 0.1 using 0.5 M dilute hydrochloric acid. Subsequently, 0.2 g of dopamine hydrochloride was added, and after stirring and dissolving, the pH was adjusted to 8.5 ± 0.1 using 5 wt% sodium hydroxide solution. The mixture was stirred at room temperature in air for 24 h, centrifuged at 8000 r / min for 10 min, and the precipitate was collected. The precipitate was washed successively with deionized water and anhydrous ethanol until the pH of the supernatant was neutral. The mixture was filtered, vacuum dried at 60 °C for 12 h, ground, and passed through a 200 mesh sieve to obtain the modified reinforcing agent.

[0039] Comparative Example 9 The raw material composition and preparation method of the wear-resistant and crack-resistant elastomer-modified recycled asphalt are basically the same as those in Example 6, except that the modifier is replaced with an equal weight of the modifier prepared by the following method: The preparation method of the modified reinforcing agent is basically the same as that in Example 4, except that L-cysteine ​​is replaced with an equal weight of L-alanine.

[0040] The nano-silicon carbide used in the embodiments and comparative examples of this application is of type XFJ30, produced by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the matrix asphalt is of type AH-70 road petroleum asphalt, produced by Liaoning Petrochemical Branch of China National Petroleum Corporation; the styrene-butadiene-styrene block copolymer is of type D-1155JOP, with a styrene content of 40wt% and a weight average molecular weight of 100,000; the rubber powder is road waste tire vulcanized rubber powder, with an average particle size of 40 mesh and a rubber hydrocarbon content of 48wt%, produced by Shandong Luke Composite Materials Co., Ltd.

[0041] The methods for preparing aged asphalt used in the embodiments and comparative examples of this application are as follows: The base asphalt was heated to a fully fluid state in an oven at 140℃, poured into a sample bottle, and placed in a rotating thin-film oven at 163℃. It was aged for 85 minutes at a rotation speed of 15 r / min and a hot air flow rate of 4000 ml / min. Subsequently, it was scraped into a stainless steel sample tray and placed in a pressure aging container. It was then aged under constant high pressure air at 100℃ and 2.1 MPa for 20 hours. After aging, the pressure was slowly released, and the product was transferred to a vacuum degassing container. It was then degassed under vacuum at 170℃ and 15 kPa absolute pressure for 30 minutes. After cooling, the aged asphalt was obtained.

[0042] The wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared in the examples and comparative examples was subjected to performance tests, and the test results are shown in Table 1.

[0043] 25℃ penetration: Tested according to the method in T0604-2011 of JTG E20-2011.

[0044] Elastic recovery rate: Tested according to the method of T0662-2000 in JTG E20-2011.

[0045] Ductility at 5℃: Tested according to the method in T0605-2011 of JTG E20-2011.

[0046] The following sample preparation methods were used to prepare the sample specimens for the examples and comparative examples for testing healing rate and abrasion resistance: Sample preparation: The modified recycled asphalt prepared in the examples and comparative examples was heated to 150±5℃ and stirred until it reached a uniform flow state. The standard sand and limestone powder were dried in an oven at 105±5℃ for 2 hours, and then preheated to 150±5℃. The components were weighed according to the mass ratio of modified recycled asphalt:standard sand:limestone powder = 1:4:1. The standard sand (quartz standard sand, SiO2 content of 96.5wt%, particle size distribution of 0.08-2.00mm) and limestone powder (CaCO3 content of 92.4wt%, average particle size less than 0.60mm, 74wt% ≤70μm) were mixed evenly and then added to the modified recycled asphalt. The mixture was stirred at 150±5℃ for 5 minutes to obtain modified recycled asphalt mortar. While still hot, the mortar was poured into a cylindrical steel mold with an inner diameter of 50mm and a height of 50mm. During the filling process, the mold was slightly vibrated to remove air bubbles. The mortar was then pressed at 5MPa for 5 minutes to ensure that the sample was compacted. After the sample cooled to room temperature with the mold, it was demolded, the edges were trimmed, and a cylindrical asphalt mortar sample with a diameter of 50 mm and a height of 50 mm was obtained. The sample was left to cure at room temperature for 24 hours.

[0047] Healing rate test: Cylindrical asphalt mortar samples were divided into an initial strength test group, a pre-cracked but unhealed group, and a pre-cracked and healed group. The initial strength test group, after equilibration at 25℃ for 2 hours, was placed between the upper and lower plates of a universal testing machine and subjected to uniaxial compression at a loading rate of 1 mm / min. The maximum load at failure was recorded, and the initial compressive strength R0 was calculated. The pre-cracked but unhealed group and the pre-cracked and healed group underwent pre-cracking treatment under the same conditions. During pre-cracking, the sample was loaded to 60% of the average initial failure load. Loading was stopped when obvious cracks appeared but no through-crack or overall collapse occurred, and the load was slowly unloaded to obtain a pre-cracked sample. The pre-cracked but unhealed group underwent a secondary compression test immediately after equilibration at 25℃ for 2 hours, and the compressive strength R0 after pre-cracking was measured. d The pre-cracked healing group was cured in a 40℃ constant temperature chamber for 48 hours, and then equilibrated at 25℃ for 2 hours. A second compression test was then conducted under the same conditions, and the compressive strength R after healing was measured. h The healing rate is calculated using the following formula:

[0048] In the formula, H is the asphalt healing rate (%), R0 is the initial compressive strength (MPa); R d R represents the unhealed compressive strength after pre-cracking, in MPa. h The compressive strength after healing is expressed in MPa.

[0049] Abrasion resistance test: The prepared sample was placed in a constant temperature environment of 25°C for 2 hours to equilibrate. The mass of the sample before wear was recorded as m0. Then, the sample was fixed on the abrasion testing machine, with the end face of the sample in contact with the abrasion wheel, and the abrasion test was carried out. The test conditions were: loading pressure of 0.5 MPa, abrasion speed of 60 r / min, and abrasion time of 30 min. After the abrasion was completed, the loose particles on the sample surface were removed, and the mass of the sample was weighed again and recorded as m1. The mass wear rate was calculated according to the following formula:

[0050] In the formula, W is the mass wear rate, %; m0 is the mass of the sample before wear, g; and m1 is the mass of the sample after wear, g.

[0051] Table 1. Test data of wear-resistant and crack-resistant elastomer-modified recycled asphalt.

[0052] As can be seen from the data in Table 1, the wear-resistant and crack-resistant elastomer-modified recycled asphalt prepared by the present invention has good low-temperature flexibility, elastic recovery, self-healing ability, and wear resistance. The reasons for the performance improvement are as follows: The long-chain fatty acid structure in the epoxidized soybean oil-modified regenerator can replenish the lightweight, flexible components lost in aged asphalt due to thermo-oxidative aging, weaken the hard and brittle structure caused by excessive association of asphaltenes in aged asphalt, and restore its fluidity, ductility, and low-temperature flexibility. The hydroxyl, ester, ether, and disulfide bond structures introduced after the reaction of 3,3'-dithiodipropionic acid with epoxidized soybean oil can enhance the interaction between the regenerator and the polar oxidation products in aged asphalt, improve dispersion stability, and alleviate stress concentration at crack tips through the dynamic rearrangement and energy dissipation of disulfide bonds, promoting the re-bonding of microcrack interfaces. Silicon carbide in the modified reinforcing agent, as a high-hardness rigid reinforcing phase, can form micro-nano support points, restricting plastic flow and surface peeling under friction and load. After synergistic modification with L-cysteine ​​and dopamine, amino, carboxyl, hydroxyl, disulfide bonds, and a polydopamine layer are introduced on its surface, which can improve the interfacial compatibility with the organic phase of asphalt and reduce agglomeration and interfacial debonding. The composite elastomer composed of SBS and rubber powder swells and disperses into a network during high-temperature shearing, forming a continuous elastic network and a toughening phase composed of particles, thus improving elastic recovery and absorbing energy during crack propagation and frictional wear. 2-Methylimidazole / N,N-dimethylbenzylamine further promotes the ring-opening or interfacial reactions of residual epoxy groups with active groups such as hydroxyl, carboxyl, and amino groups, enabling the components to form a stable multi-combined structure. Therefore, the resulting recycled asphalt possesses properties such as high elastic recovery rate, high healing rate, and low wear rate.

[0053] As can be seen from Comparative Examples 1-6, when 3,3'-dithiodipropionic acid is replaced by 3,3'-thiodipropionic acid, adipic acid, or 3-(methyldithio)-propionic acid, the modified regenerator lacks disulfide bonds or dicarboxyl bridging structures, leading to a decrease in the compatibility, interfacial bonding, and dynamic repair ability between the regenerator and aged asphalt, thus reducing ductility and healing performance at 5°C. While directly using epoxidized soybean oil can provide a softening effect, it lacks sulfur-containing dynamic structures and interfacial reinforcement structures, resulting in a decrease in healing rate and abrasion resistance. When the amount of 3,3'-dithiodipropionic acid is too low, the functional groups are insufficiently introduced; when the amount is too high, the system becomes overly polar and locally hardened, making it difficult to achieve the comprehensive performance of the examples.

[0054] Comparative Example 7, without L-cysteine, relied primarily on polydopamine for adhesion on the nano-silicon carbide surface. Lacking the interfacial bridging, dynamic energy dissipation, and crack repair functions provided by carboxyl, amino, and disulfide bonds, the particles were more prone to detachment during friction, leading to increased wear rate. Comparative Example 8, although containing L-cysteine ​​and dopamine, lacked a Tris-HCl buffer system, resulting in insufficient pH stability. This led to uneven deposition and decreased firmness of the polydopamine / L-cysteine ​​composite coating, affecting dispersion and interfacial bonding. Comparative Example 9, replacing L-cysteine ​​with L-alanine, still exhibited amino and carboxyl compatibility, but lacked the dynamic rearrangement ability of disulfide bonds, resulting in lower healing and wear resistance compared to the examples.

[0055] Figure 4 , Figure 5 , Figure 6 The images show fluorescence micrographs of the modified recycled asphalt prepared in Examples 5, 3, and 4 at different magnifications. The green fluorescent areas mainly reflect the distribution of the elastomer phase, the regenerator-enriched phase, or the modified phase in the asphalt matrix. Figure 4 The modified recycled asphalt prepared in Example 5 exhibited a uniform, continuous, and relatively fine green fluorescent network, indicating that the components were well dispersed in the aged asphalt without significant agglomeration or phase separation. The continuous network of asphalt components facilitates stress transfer, crack bridging, and energy dissipation, thereby improving elastic recovery, low-temperature ductility, healing rate, and wear resistance. Figure 5 and Figure 6 The uneven distribution of the fluorescent phase, with localized fluorescence enrichment, coarsening of the fluorescent network, and enlargement of dark areas, indicates that the compatibility of the components in the asphalt system is not as good as in Example 5.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A wear-resistant and crack-resistant elastomer-modified recycled asphalt, characterized in that, The raw materials include the following parts by weight: 90-110 parts aged asphalt, 5-8 parts modified recycling agent, 1-3 parts modified reinforcing agent, 4-8 parts composite elastomer, and 0.1-0.3 parts catalyst; The modified regenerator is 3,3'-dithiodipropionic acid-modified epoxidized soybean oil; The preparation method of the 3,3'-dithiodipropionic acid modified epoxidized soybean oil is as follows: 3,3'-Dithiodipropionic acid was prepared by reacting epoxidized soybean oil with tetrabutylammonium bromide, wherein the mass ratio of 3,3'-dithiodipropionic acid to epoxidized soybean oil was (1-1.2):

5. The modified reinforcing agent is prepared by the following method: Nano-silicon carbide was uniformly dispersed in an alkaline buffer solution, and dopamine hydrochloride and L-cysteine ​​were added to synthesize a modified and reinforcing agent in situ. The composite elastomer is made by blending styrene-butadiene-styrene block copolymer and rubber powder in a mass ratio of 1:(3-4); The catalyst is one of 2-methylimidazole and N,N-dimethylbenzylamine.

2. The wear-resistant and crack-resistant elastomer-modified recycled asphalt according to claim 1, characterized in that, The mass ratio of nano-silicon carbide, dopamine hydrochloride, and L-cysteine ​​is 10:2:

1.

3. The wear-resistant and crack-resistant elastomer-modified recycled asphalt according to claim 1, characterized in that, The alkaline buffer solution is Tris-HCl buffer solution.

4. A method for preparing wear-resistant and crack-resistant elastomer-modified recycled asphalt as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 90-110 parts aged asphalt, 5-8 parts modified recycling agent, 1-3 parts modified reinforcing agent, 4-8 parts composite elastomer, and 0.1-0.3 parts catalyst; (2) Heat and melt aged asphalt, add a mixture of modifier and regenerator to obtain recycled asphalt premix; add composite elastomer and shear at high speed, then add catalyst for constant temperature development and static degassing to obtain wear-resistant and crack-resistant elastomer modified recycled asphalt.

5. The method for preparing wear-resistant and crack-resistant elastomer-modified recycled asphalt according to claim 4, characterized in that, In step (2), the temperature at which the aged asphalt is heated and melted is 140-160℃.

6. The method for preparing wear-resistant and crack-resistant elastomer-modified recycled asphalt according to claim 4, characterized in that, In step (2), the constant temperature development time is 100-120 min and the development temperature is 150-170℃.

Images