Bio-based composite asphalt preparation method and anti-aging enhancement process thereof

Abstract

The present application relates to the technical field of road engineering materials, in particular to a kind of bio-based composite asphalt preparation method and its anti-aging enhancement process, it includes the following steps: matrix asphalt is heated to melt state, obtain molten matrix asphalt;The temperature of molten matrix asphalt is reduced to 155-165 ℃, according to the weight of matrix asphalt, modified bio-oil is added, with 500-800 rpm speed stirring;Subsequently limestone powder is added, with 3000-5000 rpm speed shearing 10-15 min;Finally, anti-aging composite agent is added, and the speed is adjusted to 500 rpm stirring 15-20 min, obtain bio-based composite asphalt.In the present application, the long-chain alkyl of modified bio-oil silanized with mercapto can fully physically entangle and polarize with asphaltene and polymer network;These polar structures can form hydrogen bond, dipole interaction and van der waals force interaction with the aromatic structure of asphaltene and the polar group in colloid, thereby improving the compatibility with asphalt matrix and reducing the separation phenomenon.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, and more specifically, to a method for preparing bio-based composite asphalt and its anti-aging enhancement process. Background Technology

[0002] With the advancement of the dual-carbon strategy and the deepening of the green road engineering concept, the limitations of traditional petroleum-based asphalt in terms of resource consumption, carbon emissions, and long-term durability have become increasingly prominent. In recent years, the preparation of bio-based modified asphalt using renewable resources such as waste vegetable oil has gradually become a research hotspot. Bio-oil molecules usually contain ester groups, hydroxyl groups, and a certain proportion of unsaturated double bonds, which have good compatibility and plasticizing effect. They can replace petroleum light components to a certain extent, thereby improving the construction performance and low-temperature crack resistance of asphalt.

[0003] However, the compatibility and interfacial bonding between bio-oil and asphalt matrix are insufficient, which makes it prone to chain scission degradation under long-term thermo-oxidative environment, resulting in asphalt hardening and embrittlement, which seriously weakens the anti-aging performance and durability of the pavement. In view of this, we propose a bio-based composite asphalt preparation method and its anti-aging enhancement process. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing bio-based composite asphalt and its anti-aging enhancement process, in order to solve the problem mentioned in the background art of insufficient compatibility and interfacial bonding between bio-oil and asphalt matrix, which leads to easy chain scission degradation under long-term thermo-oxidative environment, resulting in asphalt hardening and embrittlement, and seriously weakening the anti-aging performance and durability of the pavement.

[0005] To achieve the above objectives, the present invention provides a method for preparing bio-based composite asphalt, comprising the following steps: S1.1. Heat the base asphalt to 160-170℃ until it melts to obtain molten base asphalt; S1.2. Reduce the temperature of the molten base asphalt to 155-165℃, add 8%-15% modified bio-oil by weight of the base asphalt, and stir at 500-800 rpm for 20-30 minutes; then add 3%-8% limestone powder, and shear at 3000-5000 rpm for 10-15 minutes; finally add 0.5%-3.0% anti-aging composite agent, adjust the speed to 500 rpm and stir for 15-20 minutes to obtain bio-based composite asphalt.

[0006] Preferably, in S1.1, the base asphalt is SBS modified asphalt, and the SBS content is 4%-6%.

[0007] Preferably, in step S1.2, the modified bio-oil is prepared using the following method: Waste vegetable oil is heated to 40-50℃, peracetic acid is added dropwise, and the mixture is stirred at 300-500 rpm for 2-4 hours. After the reaction is completed, the mixture is allowed to stand and separate into layers. The aqueous phase is separated, and the oil phase is washed with deionized water at 60-70℃ until neutral. The oil phase is then distilled under reduced pressure at 80-90℃ and a vacuum of 0.085-0.095 MPa to remove water and residual acetic acid, thus obtaining epoxidized bio-oil. Raise the temperature to 75-85℃, add γ-mercaptopropyltrimethoxysilane and triethylamine to the epoxidized bio-oil, and stir at 400-500 rpm for 2-3 hours in a reactor equipped with a reflux condenser to obtain the intermediate product. The intermediate product was cooled to 60-70℃, deionized water was added, and the pH was adjusted to 4-5 with 0.5mol / L acetic acid. The reaction was maintained at this temperature for 1.0-1.5h. Then the temperature was raised to 80-90℃ and the reaction was carried out for 1-2h. After the reaction was completed, the product was distilled under reduced pressure at 90-100℃, vacuum degree 0.090-0.098MPa, and nitrogen protection for 2-3h. The product was then cooled to 60℃ to obtain the modified bio-oil.

[0008] Preferably, the mass ratio of peracetic acid to waste vegetable oil is 0.4-0.6:1.

[0009] Preferably, the molar ratio of mercapto groups in the γ-mercaptopropyltrimethoxysilane to epoxy groups in the epoxidized bio-oil is 0.8-1.1:1; and the molar ratio of triethylamine to epoxy groups in the epoxidized bio-oil is 5-10:100.

[0010] Preferably, the molar amount of deionized water is 3-5 times the molar amount of methoxy group in γ-mercaptopropyltrimethoxysilane.

[0011] Preferably, in step S1.2, the anti-aging composite agent is prepared using the following method: Montmorillonite and deionized water were mixed at a mass ratio of 1:8-10. Anhydrous sodium carbonate was added at 3%-5% of the dry weight of montmorillonite. The mixture was stirred at a high speed of 3000-5000 rpm and kept at a constant temperature of 80-90℃ for 2 hours. After standing and settling for 2-4 hours, the upper suspension was collected. The suspension was then centrifuged to remove water, yielding sodium-based montmorillonite. Sodium-based montmorillonite was redispersed in hot water at 60-70℃ to prepare a suspension with a mass fraction of 5%-10%; hexadecyltrimethylammonium bromide was added in an amount of 20%-40% of the dry weight of montmorillonite; the reaction was carried out under water bath conditions at 70-80℃ for 2-4 hours with stirring; after the reaction was completed, the mixture was filtered and washed until no bromide ions were found in the filtrate to obtain organo-modified montmorillonite; The dried nano-titanium dioxide was added to anhydrous ethanol and ultrasonically dispersed at 800W for 30 min to obtain a suspension with a mass fraction of 5%-10%. Then, γ-aminopropyltriethoxysilane was added at an amount of 1%-3% of the mass of nano-titanium dioxide, and the mixture was refluxed and stirred at 78℃ for 2 h. After centrifugation, the mixture was washed three times with ethanol and vacuum dried at 50℃ to obtain modified nano-titanium dioxide. Organized montmorillonite and modified nano-titanium dioxide were added to a high-speed mixer and dry-mixed for 10-15 minutes to obtain a mixed powder. Then, 20%-30% anhydrous ethanol was added to the mixed powder and sheared and mixed at 2000-3000 rpm for 15-20 minutes under sealed conditions at 50-60℃. The mixture was then cooled to below 40℃, and hindered amine light stabilizer HS-944 was added and mixed at a low speed of 500-800 rpm for 10-15 minutes. Finally, the mixture was vacuum dried at 40-50℃ and sieved to obtain the anti-aging composite agent.

[0012] Preferably, the mass ratio of the hindered amine light stabilizer HS-944, modified nano-titanium dioxide, and organo-modified montmorillonite is 1:0.5-1.5:0.5-1.5.

[0013] On the other hand, the present invention provides an anti-aging enhancement process for bio-based composite asphalt, used in any of the above-mentioned bio-based composite asphalt, wherein the anti-aging enhancement process is as follows: Bio-based composite asphalt is applied to the pavement surface by spraying a coating liquid when the pavement has been laid, formed, and cooled to below 50°C, with a coating amount of 100-150 g / m². 2 When naturally cured for 48-72 hours under ambient temperatures above 15℃ and without rain, a barrier and protective layer is formed.

[0014] Preferably, the preparation method of the spraying liquid is as follows: methyltrimethoxysilane and deionized water are mixed at a mass ratio of 1:10-20, the pH is adjusted to 3.5-4.5 with 0.5mol / L acetic acid, and the mixture is stirred for pre-hydrolysis for 1-2 hours; after pre-hydrolysis, the pH is adjusted to 7-9 with 0.1mol / L ammonia water, and styrene-butadiene rubber latex is added under stirring at 500-600 rpm, with a mass ratio of styrene-butadiene rubber to methyltrimethoxysilane of 0.2-0.4:1, and stirring is continued for 30 minutes to obtain the spraying liquid.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, a method for preparing bio-based composite asphalt and its anti-aging enhancement process utilizes a modified bio-oil with mercaptosilanization. The long-chain alkyl groups of this modified bio-oil can undergo sufficient physical entanglement and polar interaction with asphaltene and polymer networks. Through the ring-opening reaction of mercapto and epoxy groups, hydroxyl and silanol structures are formed within the bio-oil molecules. These polar structures can form hydrogen bonds, dipole interactions, and van der Waals interactions with the aromatic structures of asphaltene and the polar groups in the resin, thereby improving compatibility with the asphalt matrix and reducing precipitation. Organized montmorillonite, with its layered structure, effectively blocks oxygen and heat from penetrating into the asphalt. Modified nano-titanium dioxide and hindered amine light stabilizer (HS-944) work synergistically to achieve broad-spectrum ultraviolet shielding and absorption, as well as free radical capture and quenching, constructing an anti-aging barrier. This not only effectively inhibits the chain-breaking degradation of bio-oil under long-term thermo-oxidative conditions and delays the oxidative hardening and spalling of matrix components, but also significantly improves the low-temperature crack resistance and fatigue life of the pavement, ensuring its long-term stability in complex environments. Attached Figure Description

[0016] Figure 1 The contact angles of bio-based composite asphalt in Example 6 and Comparative Examples 1-4; Figure 2 The DSR fatigue curves of bio-based composite asphalt in Example 6 and Comparative Examples 1-4 are shown. Figure 3 This is a stratified diagram of the storage stability of bio-based composite bitumen in Example 6 and Comparative Examples 1-4. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] The SBS modified bitumen was purchased from Shandong Lianhai Petrochemical Co., Ltd.

[0019] Waste vegetable oil is a mixture of waste rapeseed oil and peanut oil from catering, with an iodine value of 100-130gI2 / 100g and an acid value of ≤5mgKOH / g.

[0020] γ-Mercaptopropyltrimethoxysilane (CAS No.: 4420-74-0, purity 95%), montmorillonite (CAS No.: 1318-93-0, CEC≥80mmol / 100g), γ-aminopropyltriethoxysilane (CAS No.: 919-30-2), and hindered amine light stabilizer HS-944 (CAS No.: 70624-18-9) were all purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0021] Triethylamine (CAS No.: 121-44-8) was purchased from Shandong Mingyu Supply Chain Management Co., Ltd.

[0022] Limestone powder (CAS No.: 471-34-1) was purchased from Hubei Xinrunde Chemical Co., Ltd.

[0023] The cetyltrimethylammonium bromide (CAS No.: 57-09-0) was purchased from Shanghai Xuejie Chemical Co., Ltd.

[0024] Methyltrimethoxysilane (CAS No.: 1185-55-3) was purchased from Jiangxi Hongbai New Materials Co., Ltd.

[0025] Styrene-butadiene rubber latex (solid content 45%-55%, styrene content 20%-25%, latex particle size 100-200nm) was purchased from Henan Dashu Industrial Co., Ltd.

[0026] In this invention, the mass concentration of peracetic acid is 15%.

[0027] The dried nano-titanium dioxide (rutile type, particle size 10-30nm) is obtained by placing nano-titanium dioxide in a vacuum drying oven and drying it at 105℃ for 2 hours.

[0028] Example 1: A method for preparing bio-based composite asphalt and its anti-aging enhancement process, comprising the following steps: S1.1. Heat SBS modified asphalt (SBS content is 4%) to 160℃ to a molten state to obtain molten base asphalt; S1.2. Reduce the temperature of the molten base asphalt to 155℃, add 8% modified bio-oil by weight of the base asphalt, and stir at 500 rpm for 20 min; then add 3% limestone powder and shear at 3000 rpm for 10 min; finally add 0.5% anti-aging composite agent, adjust the speed to 500 rpm and stir for 15 min to obtain bio-based composite asphalt.

[0029] The preparation method of modified bio-oil is as follows: Waste vegetable oil was heated to 40°C, and peracetic acid (the mass ratio of peracetic acid to waste vegetable oil was 0.5:1) was added dropwise. The mixture was stirred at 300 rpm for 2 hours. After the reaction was completed, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed with deionized water at 60°C until neutral. The oil phase was then distilled under reduced pressure at 80°C and a vacuum of 0.085 MPa to remove water and residual acetic acid, thus obtaining epoxidized bio-oil. The temperature was raised to 75°C, and γ-mercaptopropyltrimethoxysilane and triethylamine were added to the epoxidized bio-oil. The molar ratio of mercapto groups in γ-mercaptopropyltrimethoxysilane to epoxy groups in the epoxidized bio-oil was 1.0:1, and the molar ratio of triethylamine to epoxy groups in the epoxidized bio-oil was 5:100. The mixture was stirred at 400 rpm for 2 hours in a reactor equipped with a reflux condenser to obtain an intermediate product. The intermediate product was cooled to 60°C, and deionized water was added. The molar amount of deionized water was three times the molar amount of methoxy group in γ-mercaptopropyltrimethoxysilane. The pH was adjusted to 4 with 0.5 mol / L acetic acid, and the reaction was maintained at this temperature for 1.0 h. Subsequently, the temperature was raised to 80°C and the reaction was carried out for 1 h. After the reaction was completed, the product was distilled under reduced pressure at 90°C, a vacuum of 0.090 MPa, and nitrogen protection for 2 h. The product was then cooled to 60°C to obtain the modified bio-oil.

[0030] The preparation method of the anti-aging compound is as follows: Montmorillonite and deionized water were mixed at a mass ratio of 1:8. Anhydrous sodium carbonate was added at 3% of the dry weight of montmorillonite. The mixture was stirred at a high speed of 3000 rpm and kept at a constant temperature of 80°C for 2 hours. After standing and settling for 2 hours, the upper suspension was collected. The suspension was centrifuged and dehydrated to obtain sodium-based montmorillonite. Sodium-based montmorillonite was redispersed in hot water at 60°C to prepare a suspension with a mass fraction of 5%; hexadecyltrimethylammonium bromide was added at an amount of 20% of the dry weight of montmorillonite; the reaction was stirred for 2 hours under a water bath at 70°C; after the reaction was completed, the mixture was filtered and washed until no bromide ions were found in the filtrate to obtain organo-modified montmorillonite. The dried nano-titanium dioxide was added to anhydrous ethanol and ultrasonically dispersed at 800W for 30 min to obtain a suspension with a mass fraction of 5%. Then, γ-aminopropyltriethoxysilane was added at a mass of 1% of the nano-titanium dioxide, and the mixture was refluxed and stirred at 78℃ for 2 h. After centrifugation, the mixture was washed three times with ethanol and vacuum dried at 50℃ to obtain modified nano-titanium dioxide. Organized montmorillonite and modified nano-titanium dioxide were added to a high-speed mixer and dry-mixed for 10 min to obtain a mixed powder. Then, anhydrous ethanol (20% by mass of the mixed powder) was added, and the mixture was sheared at 2000 rpm for 15 min under sealed conditions at 50-60℃. The mixture was then cooled to below 40℃, and hindered amine light stabilizer HS-944 (the mass ratio of hindered amine light stabilizer HS-944, modified nano-titanium dioxide, and organized montmorillonite was 1:0.5:0.5) was added. The mixture was then mixed at a low speed of 500 rpm for 10 min. Finally, the mixture was vacuum dried at 40℃ and sieved to obtain the anti-aging composite agent.

[0031] Bio-based composite asphalt is applied to the pavement surface by spraying a coating liquid at a rate of 100 g / m² after the pavement has been laid, formed, and cooled to below 50°C. 2When naturally cured for 48 hours under ambient temperatures above 15℃ and no rain, a barrier and protective layer is formed. The preparation method of the spraying solution is as follows: Methyltrimethoxysilane and deionized water are mixed at a mass ratio of 1:10, the pH is adjusted to 3.5 with 0.5 mol / L acetic acid, and the mixture is stirred for pre-hydrolysis for 1 h; after the pre-hydrolysis is completed, the pH is adjusted to 7 with 0.1 mol / L ammonia water, and styrene-butadiene rubber latex is added under stirring at 500 rpm, with a mass ratio of 0.2:1 between styrene-butadiene rubber and methyltrimethoxysilane, and stirring is continued for 30 min to obtain the spraying solution.

[0032] Example 2: The difference between this example and Example 1 is that the mass ratio of peracetic acid to waste vegetable oil is 0.4:1.

[0033] Example 3: The difference between this example and Example 1 is that the mass ratio of peracetic acid to waste vegetable oil is 0.6:1.

[0034] Example 4: The difference between this example and Example 1 is that the molar ratio of the mercapto group in γ-mercaptopropyltrimethoxysilane to the epoxy group in the epoxidized bio-oil is 0.8:1.

[0035] Example 5: The difference between this example and Example 1 is that the molar ratio of the mercapto group in γ-mercaptopropyltrimethoxysilane to the epoxy group in the epoxidized bio-oil is 1.1:1.

[0036] Procedure for determining epoxy value: Accurately weigh approximately 1-2 grams (accurate to 0.0001 g) of the epoxidized bio-oil sample to be tested into a dry iodine flask; add 20 mL of hydrochloric acid-acetone solution (mix concentrated hydrochloric acid and acetone at a volume ratio of 1:40) to the flask, and gently shake to completely dissolve the sample; immediately seal the flask tightly and place it in the dark at room temperature (25℃) for 60 min, gently shaking it once every 10 min during the reaction; after the reaction is complete, add 20.00 mL of 0.1 mol / L hydrochloric acid-acetone standard solution, react for 60 min, then add 50 mL of acetone to dilute, add 3-5 drops of phenolphthalein indicator, and titrate with 0.1 mol / L sodium hydroxide ethanol standard solution until a faint red color persists for 30 seconds as the endpoint; record the volume of sodium hydroxide consumed, and calculate the epoxy value (mol / 100 g) based on the difference between the blank and the sample; the higher the epoxy value, the more complete the epoxidation reaction.

[0037] Procedure for determining the hydroxyl value: Mix acetic anhydride and pyridine at a volume ratio of 1:3 (prepare fresh before use); prepare a 0.5 mol / L potassium hydroxide-ethanol standard solution; accurately weigh 1-2 g of modified bio-oil sample (accurate to 0.0001 g), place it in a 250 mL stoppered conical flask, accurately add 10 mL of acetic anhydride-pyridine solution, attach a reflux condenser, and heat under reflux in an oil bath at 95-100℃ for 1 h; add 10 mL of distilled water from the top of the condenser, and continue heating for 10 min; after cooling, rinse the inner wall of the condenser with 20 mL of pyridine, remove the conical flask, add 3 drops of phenolphthalein indicator, and titrate with the 0.5 mol / L potassium hydroxide-ethanol standard solution until a faint pink color appears, while simultaneously performing a blank test; calculate the hydroxyl value (mgKOH / g) = ( - )×C×56.1 / m, where The blank titration volume (mL) is given. The value of 'm' represents the sample titration volume (mL), C represents the potassium hydroxide concentration (mol / L), and m represents the sample mass (g). The hydroxyl value reflects the completeness of the ring-opening reaction and the amount of silane grafting.

[0038] Table 1 Performance data of modified bio-oil ; As can be seen from Table 1, as the mass ratio of peracetic acid to waste vegetable oil increased from 0.4 (Example 2) to 0.5 (Example 1) and then to 0.6 (Example 3), the epoxy value showed an upward trend (from 0.09 mol / 100g to 0.13 mol / 100g); the hydroxyl value also increased accordingly (from 110 mg KOH / g to 168 mg KOH / g).

[0039] Peracetic acid is the oxidant in the epoxidation reaction. At a mass ratio of 0.4 (Example 2), the oxidant is insufficient to convert all unsaturated double bonds into epoxy groups, resulting in the lowest epoxy value. Increasing the mass ratio to 0.5 and 0.6 increases the double bond conversion rate and the epoxy value accordingly.

[0040] The hydroxyl groups mainly originate from the secondary hydroxyl groups generated by the ring-opening reaction of thiol groups and epoxy groups, as well as the diols generated by the side reaction of epoxy groups with water under acidic or high-temperature conditions. In Example 2, due to the small number of epoxy groups, the total amount of hydroxyl groups that can be generated subsequently is naturally the smallest. In Example 3, although the epoxy value is the highest, the excess peracetic acid and the acetic acid generated in the reaction will lead to an increase in the acidity of the system, promote the hydrolysis side reaction of epoxy groups, generate a large number of vicinal diol structures, and cause the hydroxyl value to rise abnormally. This excessive number of hydroxyl groups will increase the intermolecular hydrogen bonds, which will lead to excessive viscosity of the bio-oil and even self-polymerization during storage.

[0041] As can be seen from Table 1, when the molar ratio of mercapto to epoxy decreased from 1.0 (Example 1) to 0.8 (Example 4), the epoxy value increased sharply (from 0.12 mol / 100g to 0.18 mol / 100g), while the hydroxyl value decreased (from 145 mg KOH / g to 95 mg KOH / g); when the ratio increased to 1.1 (Example 5), the epoxy value dropped to the lowest level (0.08 mol / 100g), while the hydroxyl value increased (from 145 mg KOH / g to 178 mg KOH / g).

[0042] In Example 4, due to insufficient thiol groups, a large number of epoxy groups remained unparticipated in the ring-opening reaction after the reaction, resulting in an extremely high residual epoxy value (0.18 mol / 100g). Simultaneously, because the thiol-epoxy addition occurred less frequently, the target product (graft containing thioether bonds and hydroxyl groups) was generated in small quantities, resulting in a low hydroxyl value. The unreacted epoxy groups were prone to cross-linking and curing during subsequent high-temperature mixing of asphalt, leading to poor compatibility.

[0043] In Example 5, the excess mercaptosilane ensured that the epoxy groups were almost completely reacted (epoxide value was the lowest, 0.08); the increase in hydroxyl value (178 mg KOH / g) was mainly due to the methoxy groups in the excess silane generating more silanols (Si-OH) in the subsequent hydrolysis step, which contributed to the hydroxyl value.

[0044] Example 6: A method for preparing bio-based composite asphalt and its anti-aging enhancement process, comprising the following steps: S1.1. Heat SBS modified asphalt (SBS content is 5%) to 165℃ to a molten state to obtain molten base asphalt; S1.2. Reduce the temperature of the molten base asphalt to 160℃, add 12% modified bio-oil by weight of the base asphalt, and stir at 600 rpm for 25 min; then add 5% limestone powder and shear at 4000 rpm for 15 min; finally add 1.5% anti-aging composite agent, adjust the speed to 500 rpm and stir for 20 min to obtain bio-based composite asphalt.

[0045] The preparation method of modified bio-oil is as follows: Waste vegetable oil was heated to 50°C, and peracetic acid (the mass ratio of peracetic acid to waste vegetable oil was 0.5:1) was added dropwise. The mixture was stirred at 400 rpm for 3 hours. After the reaction was completed, the mixture was allowed to stand and separate into layers. The aqueous phase was separated, and the oil phase was washed with deionized water at 65°C until neutral. The oil phase was then distilled under reduced pressure at 85°C and a vacuum of 0.085 MPa to remove water and residual acetic acid, thus obtaining epoxidized bio-oil. The temperature was raised to 80℃, and γ-mercaptopropyltrimethoxysilane and triethylamine were added to the epoxidized bio-oil. The molar ratio of mercapto groups in γ-mercaptopropyltrimethoxysilane to epoxy groups in the epoxidized bio-oil was 1.0:1, and the molar ratio of triethylamine to epoxy groups in the epoxidized bio-oil was 8:100. The mixture was stirred at 450 rpm for 3 hours in a reactor equipped with a reflux condenser to obtain an intermediate product. The intermediate product was cooled to 65°C, and deionized water was added. The molar amount of deionized water was four times the molar amount of methoxy group in γ-mercaptopropyltrimethoxysilane. The pH was adjusted to 5 with 0.5 mol / L acetic acid, and the reaction was maintained at this temperature for 1.5 h. Subsequently, the temperature was raised to 85°C and the reaction was carried out for 2 h. After the reaction was completed, the product was distilled under reduced pressure at 95°C, a vacuum of 0.090 MPa, and nitrogen protection for 3 h. The product was then cooled to 60°C to obtain the modified bio-oil.

[0046] The preparation method of the anti-aging compound is as follows: Montmorillonite and deionized water were mixed at a mass ratio of 1:8. Anhydrous sodium carbonate was added at 4% of the dry weight of montmorillonite. The mixture was stirred at a high speed of 4000 rpm and kept at a constant temperature of 85°C for 2 hours. After standing and settling for 3 hours, the upper suspension was collected. The suspension was centrifuged and dehydrated to obtain sodium-based montmorillonite. Sodium-based montmorillonite was redispersed in hot water at 65°C to prepare a suspension with a mass fraction of 8%; hexadecyltrimethylammonium bromide was added in an amount of 30% of the dry weight of montmorillonite; the reaction was stirred for 3 hours under a water bath at 75°C; after the reaction was completed, the mixture was filtered and washed until no bromide ions were found in the filtrate to obtain organo-modified montmorillonite. The dried nano-titanium dioxide was added to anhydrous ethanol and ultrasonically dispersed at 800W for 30 min to obtain a suspension with a mass fraction of 8%. Then, γ-aminopropyltriethoxysilane was added at 2% of the mass of nano-titanium dioxide, and the mixture was refluxed and stirred at 78℃ for 2 h. After centrifugation, the mixture was washed three times with ethanol and vacuum dried at 50℃ to obtain modified nano-titanium dioxide. Organized montmorillonite and modified nano-titanium dioxide were added to a high-speed mixer and dry-mixed for 15 min to obtain a mixed powder. Then, anhydrous ethanol (25% by mass of the mixed powder) was added, and the mixture was sheared and mixed at 2500 rpm for 20 min under sealed conditions at 55°C. After cooling to below 40°C, hindered amine light stabilizer HS-944 (the mass ratio of hindered amine light stabilizer HS-944, modified nano-titanium dioxide, and organized montmorillonite was 1:1.0:1.0) was added, and the mixture was mixed at a low speed of 600 rpm for 15 min. Finally, the mixture was vacuum dried at 50°C and sieved to obtain the anti-aging composite agent.

[0047] Bio-based composite asphalt is applied to the pavement surface by spraying a coating liquid at a rate of 120 g / m² after the pavement has been laid, formed, and cooled to below 50°C. 2When naturally cured for 72 hours under ambient temperatures above 15℃ and no rain, a barrier and protective layer is formed. The preparation method of the spraying solution is as follows: Methyltrimethoxysilane and deionized water are mixed at a mass ratio of 1:15, the pH is adjusted to 4.0 with 0.5 mol / L acetic acid, and pre-hydrolyzed for 2 hours with stirring; after the pre-hydrolyzation is completed, the pH is adjusted to 8 with 0.1 mol / L ammonia water, and styrene-butadiene rubber latex is added with a mass ratio of 0.3:1 to methyltrimethoxysilane while stirring at 600 rpm to obtain the spraying solution.

[0048] Example 7: The difference between this example and Example 6 is that 8% modified bio-oil is added.

[0049] Example 8: The difference between this example and Example 6 is that 15% modified bio-oil is added.

[0050] Example 9: The difference between this example and Example 6 is that 0.5% anti-aging compound is added.

[0051] Example 10: The difference between this example and Example 6 is that 3.0% anti-aging compound agent is added.

[0052] Example 11: The difference between this example and Example 6 is that the coating amount is 100g / m². 2 .

[0053] Example 12: The difference between this example and Example 6 is that the coating amount is 150g / m². 2 .

[0054] Test method for thermo-oxidative aging resistance (viscosity ratio and ductility retention after RTFOT): Take about 35 grams of the original bio-based composite asphalt sample and inject it into a standard glass rotating flask; place the flask in a rotating thin-film oven (RTFOT) and heat it at 163℃ for 75 minutes at a speed of 15 r / min to simulate thermo-oxidative aging during construction; remove the aged asphalt and immediately place it in a constant temperature water bath to maintain the temperature to the test temperature (usually 135℃); use a Brookfield rotational viscometer with a suitable rotor (such as No. 27 or No. 29) to measure its dynamic viscosity (Pa·s) at a speed of 20 r / min; at the same time, measure the viscosity of the unaged original sample; calculate the viscosity ratio = viscosity after aging / original viscosity; the closer the ratio is to 1, the stronger the thermo-oxidative hardening resistance. Another portion of the aged asphalt was injected into a figure-eight mold and cooled at room temperature. Then it was placed in a constant temperature water bath at 25℃ (or 15℃, 10℃, depending on the grade) for 1-1.5 hours. The ductility tester was started and stretched at a speed of 5cm / min. The length (cm) at which the specimen broke was recorded. At the same time, the ductility of the original sample was measured. The ductility retention rate was calculated as (ductility after aging / original ductility) × 100%. The higher the retention rate, the stronger the material's resistance to embrittlement and the better the toughening effect of the modified bio-oil.

[0055] Surface protective layer performance testing (static contact angle and pull-out adhesion strength) method: Select a flat asphalt mixture specimen or compacted asphalt slab, spray the coating liquid according to the process requirements, and cure it under standard conditions (>15℃, no rain) for 72 hours to form a complete protective layer; use a contact angle measuring instrument to gently deposit water droplets (about 5μL) on the surface of the protective layer through a micro-injector, avoiding impact damage to the surface; the instrument's camera captures the side profile of the water droplet, the software automatically fits the tangent, and reads the left and right contact angle values, taking the average value; the larger the contact angle, the better the hydrophobicity and the stronger the waterproof penetration ability; On the well-maintained sprayed pavement, use high-strength epoxy resin adhesive to vertically attach a standard-sized metal pull-out head (usually 50mm in diameter) to the surface of the protective layer, ensuring that the adhesive layer is uniform and free of air bubbles; wait for the epoxy adhesive to fully cure (usually 24 hours); align the portable pull-out instrument vertically with the pull-out head and apply a tensile force at a uniform speed (approximately 1MPa / s loading rate) until the protective layer breaks off (peels) from the pavement base layer; record the maximum pull-out force (N) and calculate the adhesion strength (MPa = force / area).

[0056] Table 2 Performance data of bio-based composite asphalt ; Comparing Examples 6, 7, and 8 in Table 2, as the amount of bio-oil increased from 8% (Example 7) to 12% (Example 6) and then to 15% (Example 8), the viscosity ratio after RTFOT gradually decreased (from 1.62 to 1.38), and the ductility retention rate increased (from 65.2% to 82.0%).

[0057] However, the static contact angle and pull-out strength decreased slightly in Example 8.

[0058] Bio-oil is rich in light components and flexible long chains, which can effectively replenish the oil lost by SBS asphalt during aging, soften the colloidal structure of hardened asphalt, thereby significantly reducing the viscosity ratio after aging and improving the ductility retention rate.

[0059] When the dosage reaches 15% (Example 8), although the low-temperature performance is optimal, the excessive light oil dilutes the concentration of asphaltenes and SBS, resulting in a decrease in the complex modulus at high temperatures, which leads to a risk of high-temperature stability. In addition, the excessive bio-oil will approach the compatibility limit, resulting in surface energy fine-tuning and slightly affecting the wetting compatibility of the external coating.

[0060] Comparing Examples 6, 9, and 10 in Table 2, when the amount of anti-aging compound agent increased from 0.5% (Example 9) to 1.5% (Example 6), the viscosity ratio decreased significantly and the ductility retention rate increased sharply.

[0061] When the dosage was further increased to 3.0% (Example 10), the improvement in various indicators was minimal (viscosity ratio 1.48, ductility 76.0%).

[0062] At a low dosage of 0.5% (Example 9), organic montmorillonite and nano-TiO2 failed to form a continuous barrier network and UV shielding layer in the asphalt matrix, and the concentration of free radical scavenger (HS-944) was also insufficient, resulting in weak antioxidant capacity and severe aging.

[0063] When the dosage reaches 1.5% (Example 6), the nanoparticles are well dispersed and form an effective three-dimensional protective network, and the anti-aging efficiency reaches its peak. When the dosage is increased to 3.0% (Example 10), the inorganic powder is more difficult to disperse in high-viscosity asphalt and is prone to secondary agglomeration. This not only fails to further improve the barrier effect, but also introduces defects and increases the viscosity of the system.

[0064] Comparing Examples 6, 11, and 12 in Table 2, the coating amount ranged from 100 g / m². 2 (Example 11) Increased to 120 g / m 2 (Example 6) Then to 150g / m 2 (Example 12) The static contact angle continued to increase, indicating that the hydrophobicity was enhanced; however, the pull-out adhesion strength showed a trend of first increasing and then decreasing.

[0065] Coating amount 100g / m 2 In Example 11, the siloxane-styrene-butadiene rubber film formed by the spraying liquid is relatively thin and cannot completely cover the micropores and textures of the road surface. It has pinholes or defects, which makes it easy for water vapor to penetrate (low contact angle), and the mechanical interlocking force is insufficient, resulting in poor adhesion.

[0066] Coating amount 120g / m 2 (Example 6) In this case, a continuous, dense and appropriately thick protective film was formed, which not only ensured hydrophobicity, but also established a physical interlock with the road surface through penetration anchoring, and the adhesion reached its peak.

[0067] When the coating amount reaches 150g / m2 In Example 12, the coating was too thick; during the evaporation of moisture and the curing of silane polycondensation, the surface layer dried faster than the bottom layer, resulting in greater shrinkage internal stress; this internal stress weakened the bonding force between the coating and the base layer, leading to a decrease in pull-out strength; although the surface was enriched with more hydrophobic groups, which slightly increased the contact angle, the excessively thick organic film was more prone to shear failure or peeling under actual traffic loads.

[0068] Based on the above measurements, Example 6 achieved the best balance between internal toughening and crack resistance of asphalt (high ductility retention rate of 78.5%) and external dense protection (high contact angle of 108° and strong adhesion of 0.65MPa), effectively avoiding defects such as high-temperature instability, dispersion and agglomeration or stress spalling of the coating caused by excessive components. Therefore, Example 6 is regarded as the optimal example. Comparative Example 1: The difference between this comparative example and Example 6 is that no modified bio-oil was used; instead, waste vegetable oil was used directly.

[0069] Comparative Example 2: This comparative example differs from Example 6 in that γ-mercaptopropyltrimethoxysilane was not added.

[0070] Comparative Example 3: This comparative example differs from Example 6 in that no anti-aging compound was added.

[0071] Comparative Example 4: This comparative example differs from Example 6 in that no road surface spraying treatment was performed.

[0072] DSR fatigue curve determination method: The fatigue performance of bio-based composite asphalt was determined using a dynamic shear rheometer (DSR). Each prepared sample was placed on a DSR testing platform, with the testing temperature set at 64℃ and the frequency at 1Hz. First, the linear viscoelastic region was determined through strain scanning, followed by time-scan testing with a controlled strain mode at 1% strain amplitude. The test started from the first cycle and continued until 100,000 cycles were reached to simulate the stress accumulation effect during long-term pavement service. During the experiment, the complex shear modulus (G*) was recorded every 1000 cycles, and its ratio to the initial modulus (G0) was calculated. Each sample group was tested at least three times to ensure data reproducibility. Finally, fatigue decay curves were plotted with the number of cycles as the x-axis and the modulus ratio as the y-axis. The fatigue durability and modulus decay rate of each sample were evaluated by comparing the curve trends.

[0073] Method for determining storage stability (difference in softening point due to segregation): Approximately 50 grams of hot bio-based asphalt is injected into a specially designed aluminum segregation tube (approximately 25 mm in diameter and 140 mm in height), immediately fixed vertically with clamps, and placed in an oven. The tube is then stored statically in an oven at 163±5℃ for 48 hours, during which time movement or vibration is strictly prohibited, simulating a high-temperature storage process. After 48 hours, the aluminum tube is carefully removed and quickly placed in a freezer for at least 8 hours to allow the asphalt to fully harden. The frozen aluminum tube is then removed and horizontally cut into three equal parts (upper, middle, and lower) with a sharp blade. Samples of the upper 1 / 3 and lower 1 / 3 of the asphalt are taken separately. The ring and ball softening points of the upper and lower samples are measured separately. The difference between the upper and lower softening points is calculated. If the difference is ≤2.5℃, it indicates excellent compatibility between the modified bio-oil and the asphalt, with no macroscopic phase separation. If the difference is >2.5℃, it indicates severe segregation.

[0074] Table 3 Performance data of bio-based composite asphalt ; As can be seen from Table 3, compared with Comparative Examples 1 and 2, the viscosity ratio of Comparative Example 1 (direct addition of waste vegetable oil) after RTFOT in Example 6 soared to 2.35, and the ductility retention rate plummeted to 38.2%. Comparative Example 2 (epoxidation only, no silane grafting) showed some improvement in performance (viscosity ratio 1.92, ductility 52.4%), but was still inferior to Example 6 (viscosity ratio 1.45, ductility 78.5%).

[0075] The segregation difference in Comparative Example 1 was as high as 11.1°C, in Comparative Example 2 it was 5.7°C, while in Example 6 it was only 1.4°C.

[0076] In Comparative Example 1, the waste vegetable oil is mainly composed of non-polar triglycerides, which have extremely poor compatibility with the highly polar SBS modified asphalt. During the thermo-oxidative aging process, the light oil is very prone to phase separation (segregation) and volatilization, which leads to the rapid destruction of the asphalt colloidal structure, manifested as a sharp increase in viscosity and loss of ductility.

[0077] Although the epoxidation in Comparative Example 2 introduced polar epoxy groups and improved some compatibility, it lacked γ-mercaptopropyltrimethoxysilane, and the bio-oil molecules still migrated under long-term stress and heat. In Example 6, the thiol-epoxy addition and subsequent silanol condensation of the silane-modified bio-oil caused the bio-oil to form a certain degree of micro-crosslinked structure. This structure formed strong interfacial physical adsorption, entanglement and polar interaction with SBS and asphaltenes, thereby effectively inhibiting bio-oil migration and improving aging stability.

[0078] The segregation difference of Comparative Example 3 (2.2°C) and Comparative Example 4 (1.6°C) was not significantly different from that of Example 6 (1.4°C).

[0079] The viscosity ratio (1.78) and ductility retention rate (61.5%) of Comparative Example 3 were significantly lower than those of Example 6. The modified bio-oil mainly served to supplement the light components and reduce stiffness, but it did not have the ability to actively resist oxygen penetration and ultraviolet radiation. The anti-aging compound added in Example 6 played a triple role: the layered structure of the organic montmorillonite created a gas barrier and delayed oxygen diffusion; nano-TiO2 shielded the destructive ultraviolet rays; and HS-944 efficiently captured oxidative free radicals. Without this system (Comparative Example 3), the oxidation chain reaction inside the asphalt could not be effectively blocked, resulting in a deeper degree of aging.

[0080] The internal properties of Comparative Example 4 (without coating) (viscosity ratio 1.48, ductility 76.8%) are very close to those of Example 6; however, its static contact angle is <72° and there is no pull-out adhesion strength data (due to the lack of coating).

[0081] The aging of asphalt pavement usually starts from the surface and gradually extends inward; although Comparative Example 4 has strong internal anti-aging ability, the pavement is directly exposed to sunlight, rain and air; the low contact angle (<72°) means that rainwater can easily wet and penetrate into the micropores of the pavement, accelerating water damage and peeling; direct ultraviolet radiation on the surface layer will cause the surface asphalt to harden rapidly and produce microcracks.

[0082] The aqueous silane-SBR protective layer on the surface of Example 6 provides a hydrophobic angle of up to 108°, effectively blocking moisture intrusion; at the same time, the coating acts as a physical barrier to reflect / absorb ultraviolet rays, protecting the underlying asphalt; the pull-out strength of 0.65 MPa proves the strong bond between the coating and the road surface, ensuring durable protection.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing bio-based composite asphalt, characterized in that, Includes the following steps: S1.

1. Heat the base asphalt to 160-170℃ until it melts to obtain molten base asphalt; S1.

2. Reduce the temperature of the molten base asphalt to 155-165℃, add 8%-15% modified bio-oil by weight of the base asphalt, and stir at 500-800 rpm for 20-30 minutes; then add 3%-8% limestone powder, and shear at 3000-5000 rpm for 10-15 minutes; finally add 0.5%-3.0% anti-aging composite agent, adjust the speed to 500 rpm and stir for 15-20 minutes to obtain bio-based composite asphalt.

2. The method for preparing bio-based composite asphalt according to claim 1, characterized in that, In S1.1, the base asphalt is SBS modified asphalt, and the SBS content is 4%-6%.

3. The method for preparing bio-based composite asphalt according to claim 1, characterized in that, In step S1.2, the method for preparing the modified bio-oil is as follows: Waste vegetable oil is heated to 40-50℃, peracetic acid is added dropwise, and the mixture is stirred at 300-500 rpm for 2-4 hours. After the reaction is completed, the mixture is allowed to stand and separate into layers. The aqueous phase is separated, and the oil phase is washed with deionized water at 60-70℃ until neutral. The oil phase is then distilled under reduced pressure at 80-90℃ and a vacuum of 0.085-0.095 MPa to remove water and residual acetic acid, thus obtaining epoxidized bio-oil. Raise the temperature to 75-85℃, add γ-mercaptopropyltrimethoxysilane and triethylamine to the epoxidized bio-oil, and stir at 400-500 rpm for 2-3 hours in a reactor equipped with a reflux condenser to obtain the intermediate product. The intermediate product was cooled to 60-70℃, deionized water was added, and the pH was adjusted to 4-5 with 0.5mol / L acetic acid. The reaction was maintained at this temperature for 1.0-1.5h. Then the temperature was raised to 80-90℃ and the reaction was carried out for 1-2h. After the reaction was completed, the product was distilled under reduced pressure at 90-100℃, vacuum degree 0.090-0.098MPa, and nitrogen protection for 2-3h. The product was then cooled to 60℃ to obtain the modified bio-oil.

4. The method for preparing bio-based composite asphalt according to claim 3, characterized in that, The mass ratio of peracetic acid to waste vegetable oil is 0.4-0.6:

1.

5. The method for preparing bio-based composite asphalt according to claim 3, characterized in that, The molar ratio of mercapto groups in the γ-mercaptopropyltrimethoxysilane to epoxy groups in the epoxidized bio-oil is 0.8-1.1:1; the molar ratio of triethylamine to epoxy groups in the epoxidized bio-oil is 5-10:

100.

6. The method for preparing bio-based composite asphalt according to claim 3, characterized in that, The molar amount of deionized water is 3-5 times the molar amount of methoxy group in γ-mercaptopropyltrimethoxysilane.

7. The method for preparing bio-based composite asphalt according to claim 1, characterized in that, In step S1.2, the preparation method of the anti-aging composite agent is as follows: Montmorillonite and deionized water were mixed at a mass ratio of 1:8-10. Anhydrous sodium carbonate was added at 3%-5% of the dry weight of montmorillonite. The mixture was stirred at a high speed of 3000-5000 rpm and kept at a constant temperature of 80-90℃ for 2 hours. After standing and settling for 2-4 hours, the upper suspension was collected. The suspension was then centrifuged to remove water, yielding sodium-based montmorillonite. Sodium-based montmorillonite was redispersed in hot water at 60-70℃ to prepare a suspension with a mass fraction of 5%-10%; hexadecyltrimethylammonium bromide was added in an amount of 20%-40% of the dry weight of montmorillonite; the reaction was carried out under water bath conditions at 70-80℃ for 2-4 hours with stirring; after the reaction was completed, the mixture was filtered and washed until no bromide ions were found in the filtrate to obtain organo-modified montmorillonite; The dried nano-titanium dioxide was added to anhydrous ethanol and ultrasonically dispersed at 800W for 30 minutes to obtain a suspension with a mass fraction of 5%-10%; then γ-aminopropyltriethoxysilane was added, with an amount of 1%-3% of the mass of nano-titanium dioxide, and the mixture was refluxed and stirred at 78℃ for 2 hours. Centrifugation, washing three times with ethanol, and vacuum drying at 50°C yielded modified nano-titanium dioxide. Organized montmorillonite and modified nano-titanium dioxide were added to a high-speed mixer and dry-mixed for 10-15 minutes to obtain a mixed powder. Then, 20%-30% anhydrous ethanol was added to the mixed powder and sheared and mixed at 2000-3000 rpm for 15-20 minutes under sealed conditions at 50-60℃. The mixture was then cooled to below 40℃, and hindered amine light stabilizer HS-944 was added and mixed at a low speed of 500-800 rpm for 10-15 minutes. Finally, the mixture was vacuum dried at 40-50℃ and sieved to obtain the anti-aging composite agent.

8. The method for preparing bio-based composite asphalt according to claim 7, characterized in that, The mass ratio of the hindered amine light stabilizer HS-944, modified nano titanium dioxide, and organo-modified montmorillonite is 1:0.5-1.5:0.5-1.

5.

9. An anti-aging enhancement process for bio-based composite asphalt, used to prepare bio-based composite asphalt as described in any one of claims 1-8, characterized in that, The anti-aging enhancement process is as follows: Bio-based composite asphalt is applied to the pavement surface by spraying a coating liquid when the pavement has been laid, formed, and cooled to below 50°C, with a coating amount of 100-150 g / m². 2 When naturally cured for 48-72 hours under ambient temperatures above 15℃ and without rain, a barrier and protective layer is formed.

10. The anti-aging enhancement process for bio-based composite asphalt according to claim 9, characterized in that, The preparation method of the spraying liquid is as follows: Methyltrimethoxysilane and deionized water are mixed at a mass ratio of 1:10-20, and the pH is adjusted to 3.5-4.5 with 0.5mol / L acetic acid. The mixture is stirred and pre-hydrolyzed for 1-2 hours. After the pre-hydrolysis is completed, the pH is adjusted to 7-9 with 0.1mol / L ammonia water. Styrene-butadiene rubber latex is added while stirring at 500-600 rpm, with a mass ratio of styrene-butadiene rubber to methyltrimethoxysilane of 0.2-0.4:

1. The mixture is stirred for another 30 minutes to obtain the spraying liquid.

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