A bio-based composite recycling agent composition for hot in-place recycling, a preparation method and application thereof

Abstract

The application belongs to the technical field of asphalt pavement recycling, and particularly relates to a bio-based recycling agent for hot in-place recycling, and a preparation method and application thereof. The recycling agent is prepared from non-saturated bio-oil and petroleum refining vacuum residue as main materials, liquid rubber as a modifier, and a proper amount of thermal oxygen stabilizer. Through precise chemical crosslinking of high-activity conjugated unsaturated bonds in the bio-oil and the end groups of the liquid rubber, a 'flexible and rigid' reinforcing network is constructed, the interface penetration and adhesion of new and old materials are enhanced, the anti-fatigue, water damage resistance and low-temperature crack resistance of the recycled asphalt mixture are improved, and the efficient and long-lasting recovery of the aging asphalt performance is realized.

Description

Technical Field

[0001] This invention belongs to the field of asphalt pavement recycling technology, and relates to the composition, preparation method and application of a bio-based composite regenerator for in-situ thermal recycling. Background Technology

[0002] Asphalt pavement, due to its advantages such as high smoothness, driving comfort, and convenient construction, has become the mainstream form of highway construction in my country. Asphalt is prepared from petroleum vacuum residue through oxygen-blown thermal aging. During long-term service, it is subjected to the coupled effects of traffic loads, light, heat, and water, leading to thermal-oxygen and photo-aging. This results in the volatilization of lightweight components, component evolution, and damage to the colloidal structure, causing pavement defects such as cracking, potholes, and rutting. For asphalt pavement maintenance projects, this presents both significant challenges and new opportunities. In-situ thermal recycling of asphalt pavement is one of the core technologies in the field of road maintenance, with advantages including resource conservation, environmental friendliness and low carbon emissions, high construction efficiency, and controllable quality. In recent years, to alleviate defects and achieve resource recycling, asphalt pavement maintenance equipment companies, in conjunction with road operation companies, have focused on green, low-carbon, and intelligent manufacturing, constructing thermal recycling pavement test sections on highways across the country. The effects are being continuously observed and verified, accelerating the iterative upgrading of thermal recycling equipment and the continuous improvement of technology. In addition, highway operation and maintenance units are gradually recognizing and favoring in-situ thermal recycling technology, which is showing a trend of large-scale promotion and application.

[0003] As a core component of in-situ thermal recycling technology, rejuvenating agents can repair the performance of aged asphalt and strengthen interfacial adhesion. Their performance directly determines the engineering practical effect of recycling technology, making them a current research hotspot. Currently, because commercially available rejuvenating agent raw materials are generally non-renewable and have poor compatibility with aged asphalt, bio-based rejuvenating agents have become a research focus. For example, invention patent application number CN201911409985.2 discloses a bio-based rejuvenating agent, its preparation method, and its application; invention patent application number CN202310972411.6 discloses a vegetable oil-based SBS modified asphalt rejuvenating agent, its preparation method, and its application. First, although both patents use vegetable oil as a raw material for the recycling agent, they do not conduct component optimization design of the recycling agent in accordance with the technical requirements for asphalt recycling agents in the "Technical Specification for Recycling of Highway Asphalt Pavement" (JTG / T 5521—2019). Second, the molecular structure of vegetable oil is very different from that of asphalt components, and different vegetable oils also have different molecular structures. Furthermore, they do not focus on solving key technical problems such as the repair of old asphalt components and the bonding between new and old aggregates. Finally, there is no significant chemical cross-linking between the components, and they are mostly physically mixed. The interfacial effect is weak, and the long-term stability is insufficient. The effect on improving the road performance of the recycled mixture is limited, and it is difficult to meet the requirements for in-situ thermal recycling of high-grade highway asphalt pavement.

[0004] To address the limitations of existing thermal recyclers, the development of environmentally friendly, widely sourced, and high-performance bio-based recyclers is of great significance. Based on this, this invention prioritizes bio-based materials, modifying materials, and excipients to develop a composition and preparation method for a bio-based composite recycler for in-situ thermal recycling, comprehensively improving the road performance of recycled mixtures. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a bio-based composite regenerator for in-situ thermal regeneration, its composition, preparation method, and application. The development and utilization of bio-based materials is a hot topic in green and low-carbon development. Petroleum-based vacuum residue, which shares similarities with asphalt, possesses the characteristics of high-quality base oils, and both have potential for interdisciplinary collaboration and high-value utilization. The bio-based composite regenerator of this invention uses specific unsaturated bio-oils (including raw tung oil, methyl ricinoleate, linseed oil, and perilla oil) and petroleum-based vacuum residue to form a composite base oil. On one hand, the highly active conjugated unsaturated bonds in the unsaturated bio-oil chemically crosslink with carboxyl-terminated polyisoprene liquid rubber; on the other hand, the alkene and hydrocarbon free radicals abundant in the petroleum-based vacuum residue undergo addition reactions with the conjugated unsaturated bonds of the unsaturated bio-oil polymer chains, thereby constructing a multi-level "rigid-flexible" reinforcing network. Furthermore, by utilizing the gradient penetration and component replenishment functions of the residue, it synergistically improves the fatigue resistance, water damage resistance, and low-temperature crack resistance of recycled asphalt mixtures, achieving efficient and long-lasting recovery of the properties of aged asphalt. This invention can improve the recycling technology of asphalt pavement, thereby promoting the high-value utilization of vacuum residue oil, realizing the resource value of recycled asphalt mixtures, and is of great significance to the low-carbon development of highway maintenance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention discloses a bio-based composite regenerator for in-situ thermal regeneration, comprising a composite unsaturated bio-oil and petroleum-based vacuum residue, wherein the composite unsaturated bio-oil comprises tung oil, methyl ricinoleate, linseed oil and perilla oil.

[0007] Specifically, the petroleum-based vacuum residue is derived from petroleum vacuum distillation tailings.

[0008] Specifically, the raw tung oil, methyl ricinoleate, linseed oil, and perilla oil have different molecular structure characteristics. Raw tung oil has the largest molecular weight, with an average molecular weight of approximately 980~1105 g / mol. Linseed oil and perilla oil have similar molecular weights, with an average molecular weight of approximately 850~920 g / mol. Methyl ricinoleate is a monofatty acid methyl ester with the smallest molecular weight, at 312.49 g / mol. The larger the molecular weight, the greater the viscosity. Generally, those with larger molecular weights have a significant cross-linking effect, while those with smaller molecular weights have a significant penetration effect.

[0009] Specifically, the bio-based composite regenerator uses raw tung oil (iodine value 165-175) as the main driving force for chemical cross-linking. Its unique conjugated trienoic acid structure can undergo a highly efficient Diels-Alder reaction with liquid rubber to construct a covalent network framework. Methyl ricinoleate (iodine value 80-90), although low in unsaturation, mainly acts as an interface modifier due to its unique hydroxyl groups, enhancing the compatibility and adhesion between the regenerator and aged asphalt through hydrogen bonds. Flaxseed oil (iodine value 170-200) and perilla oil (iodine value 180-210), with their extremely high iodine values, are rich in a large amount of non-conjugated polyenoic acids. Their core function is to fully replenish the oil lost by aged asphalt, achieve basic softening, and synergistically regulate the uniform formation of the cross-linked network.

[0010] More specifically, the iodine value is an indicator that measures the degree of unsaturation or the number of double bonds in the molecular structure of bio-oil. The higher the iodine value, the more double bonds there are and the higher the degree of unsaturation.

[0011] Specifically, the compound system composed of raw tung oil, methyl ricinoleate, linseed oil and perilla oil achieves efficient regeneration from component supplementation to cross-linking enhancement through the synergistic design of "raw tung oil providing cross-linking anchors, methyl ricinoleate providing interfacial grippers, and linseed oil and perilla oil providing supplementary base materials".

[0012] Specifically, the preferred mass ratio of the raw tung oil, methyl ricinoleate, linseed oil, and perilla oil is 4:2:2:2.

[0013] Secondly, the present invention discloses a method for preparing a bio-based regenerator for in-situ thermal regeneration as described in any of the above claims, comprising the following steps: S1. The raw tung oil, methyl ricinoleate, linseed oil and perilla oil are compounded in a specific mass ratio and then dehydrated to obtain a composite unsaturated bio-oil. S2. First, the composite unsaturated bio-oil and petroleum-based vacuum residue in a specific mass ratio are added to a reactor and premixed to form a homogeneous mixed oil phase. Then, liquid rubber, antioxidant and surfactant are added to the homogeneous mixed oil phase in sequence. After stirring again, Bio-I asphalt pavement high-performance thermal recycling agent is obtained.

[0014] Specifically, in S1, the water content of the composite unsaturated bio-oil is ≤0.5%.

[0015] Specifically, in S1, the total iodine value of the composite unsaturated bio-oil is >160 gI2 / 100g, and the total acid value is <5mgKOH / g; among which, the iodine value of methyl ricinoleate is 80~90gI2 / 100g, the iodine value of flaxseed oil is 170~200gI2 / 100g, and the iodine value of perilla oil is 180~210gI2 / 100g.

[0016] Specifically, in S2, the softening point of the petroleum-based vacuum residue is 35~50℃, and the penetration (25℃) is 50~200 (0.1mm).

[0017] Furthermore, in S2, the mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:(1.50~2.50).

[0018] Further, in S2, the liquid rubber accounts for 5-10% of the total mass of the homogeneous mixed oil phase, the antioxidant accounts for 0.5-2% of the total mass of the homogeneous mixed oil phase, and the surfactant accounts for 1-3% of the total mass of the homogeneous mixed oil phase.

[0019] Specifically, the liquid rubber is preferably a carboxyl-terminated polyisoprene liquid rubber, which has excellent film-forming properties and crosslinking activity, with a number-average molecular weight between 4000 and 4800, a double bond content ≥85%, and a carboxyl functionality preferably between 1.8 and 2.0.

[0020] Specifically, the antioxidant is preferably BHT.

[0021] Specifically, the surfactant is preferably an alkylamine surfactant, including but not limited to cocoamine.

[0022] Furthermore, in S2, the premixing temperature is 30~40℃, the mixing speed is 800~1000r / min, and the time is 10~20min.

[0023] Furthermore, in S2, the re-stirring temperature is 40~50℃, the stirring speed is 800~1000r / min, and the time is 20~30min.

[0024] Thirdly, this invention discloses the bio-based composite regenerator for in-situ thermal recycling as described in any of the above claims and its preparation method, and its application in in-situ thermal recycling projects for asphalt pavements.

[0025] Specifically, the regenerant has an effective usage period of 7 days from the date of its preparation, and engineering applications should be completed within this period.

[0026] Furthermore, in the in-situ hot recycling of asphalt pavement, the amount of Bio-Ⅰ high-performance hot recycling agent added is 3~8% of the mass of aged asphalt, and the construction temperature is 155~175℃.

[0027] Specifically, the preferred amount of Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is 6% of the mass of aged asphalt.

[0028] Compared with the prior art, the present invention has the following beneficial effects: This patent uses unsaturated bio-oil and petroleum refining vacuum residue as the main raw materials, liquid rubber as a modifier, and an appropriate amount of thermal and oxygen stabilizer, and is prepared by mixing. The main technological innovations are reflected in the following aspects: First, this invention utilizes the Diels-Alder reaction combined with hydrogen bonding. During the thermal regeneration process, the residual heat of the mixture (the aggregate temperature is generally between 175℃ and 185℃) promotes the precise chemical crosslinking of the composite unsaturated bio-oil and the carboxyl-terminated polyisoprene liquid rubber. This transforms the physical blending method in traditional bio-based regenerators into a double bond of "covalent bond + hydrogen bond", fundamentally strengthening the interfacial interaction. At the same time, the self-polymerization reaction of the unsaturated bio-oil forms a hydrophobic film, constructing a highly efficient heat and oxygen aging resistant protective layer that effectively blocks the intrusion of moisture media. Furthermore, the conjugated unsaturated bonds of the composite unsaturated bio-oil polymer segments can capture the active sites of the liquid rubber end groups, autonomously cross-linking to form a network structure and creating a "hard phase region," thereby enhancing the bonding strength of the recycling agent. Further, relying on the flexibility of the liquid rubber polymer segments, a "soft phase region" is formed, improving the flexibility of the Bio-I asphalt pavement high-performance thermal recycling agent. This constructs a "rigid-flexible" reinforcing network, enhancing the interfacial penetration and bonding of new and old materials, and synergistically improving the fatigue resistance, water damage resistance, and low-temperature crack resistance of recycled asphalt mixtures, achieving efficient and long-lasting recovery of the properties of aged asphalt.

[0029] Secondly, this invention uses raw tung oil, methyl ricinoleate, linseed oil and perilla oil to prepare a composite unsaturated bio-oil, achieving complementary active functions of each component and significantly improving the interfacial compatibility and interfacial adhesion of the system. The petroleum-based vacuum residue is rich in saturated and aromatic asphalt-based components, which can compensate for the components of aged asphalt, restore the original asphalt component structure, delay the continuous aging of old asphalt, and fully utilize the bonding performance and residual value of old asphalt, effectively solving the technical problem of component compatibility and durability of recycled asphalt systems.

[0030] Third, the olefin and hydrocarbon free radicals abundant in petroleum-based vacuum residue can undergo addition reactions with the conjugated unsaturated bonds of unsaturated bio-oil polymer chains, thereby promoting the formation of a three-phase cross-linked structure of unsaturated bio-oil, liquid rubber, and petroleum refining vacuum residue, significantly improving the performance and thermo-oxidative stability of Bio-I asphalt pavement high-performance thermal recycling agent. Attached Figure Description

[0031] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 This is a schematic diagram of the crosslinking reaction between the unsaturated bonds of raw tung oil and liquid polybutadiene rubber in the Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement of the present invention. Figure 3 This refers to the Bio-I high-performance thermal recycling agent for asphalt pavement prepared in Example 1 of the present invention; Figure 4 The specimen is a mixture obtained by incorporating the Bio-I high-performance thermal recycling agent for asphalt pavement prepared in Example 1 of this invention into recycled asphalt. Detailed Implementation

[0034] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0035] To enable those skilled in the art to better understand the technical solution of this invention, based on the rotary evaporator method (T0727-2025) in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), old asphalt was recovered from old asphalt mixtures to provide raw materials for the example tests, and also served as Comparative Example 1 (DB-1). By changing the key materials of the heat recycling agent—using the ratio of composite unsaturated bio-oil, petroleum-based vacuum residue, and liquid rubber as a starting point—the preferred blending ratios of antioxidants and surfactants were simultaneously limited, wherein the preferred dosage of antioxidants was 1.25%, and the preferred dosage of surfactants was 2%. Based on the above-mentioned preferred parameters of antioxidants and surfactants, the material ratio design of the example was carried out, and other different dosage combinations were also set to form a multi-gradient ratio scheme. The invention will be further described in detail below with reference to the accompanying drawings and examples.

[0036] Example 1 like Figure 1 As shown, this embodiment provides a method for preparing a bio-based regenerator for in-situ thermal regeneration, including the following steps: S1. The raw tung oil, methyl ricinoleate, linseed oil and perilla oil are compounded in a mass ratio of 4:2:2:2, and then dehydrated to a moisture content of ≤0.5% to obtain a composite unsaturated bio-oil. Specifically, the iodine value of methyl castor oil is 86 gI2 / 100g, the iodine value of flaxseed oil is 180 gI2 / 100g, and the iodine value of perilla oil is 192 gI2 / 100g.

[0037] Specifically, the softening point of the petroleum-based vacuum residue is 41°C, and the penetration (25°C) is 115 (0.1 mm).

[0038] S2. The composite unsaturated bio-oil and petroleum-based vacuum residue in a mass ratio of 1:2.50 are added to a reactor and premixed to form a homogeneous mixed oil phase. Then, liquid rubber, antioxidant, and surfactant are added sequentially to the homogeneous mixed oil phase, and the mixture is stirred again. Figure 3 As shown, the final product was a Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement, designated BR-1.

[0039] Specifically, the premixing temperature is 30℃, the mixing speed is 800 r / min, and the time is 10 min.

[0040] Specifically, the liquid rubber is carboxyl-terminated polyisoprene liquid rubber, accounting for 5.77% of the total mass of the mixed oil phase; the antioxidant is BHT, accounting for 0.5% of the total mass of the mixed oil phase; and the surfactant is cocoagulamine, accounting for 3% of the total mass of the mixed oil phase.

[0041] Specifically, the terminal carboxyl polyisoprene liquid rubber has a number-average molecular weight of 4280, a double bond content of 88%, and a carboxyl functionality of 2.0.

[0042] Specifically, the temperature for the second stirring is 40°C, the stirring speed is 800 r / min, and the time is 20 min.

[0043] S3. Add the Bio-I high-performance hot recycling agent for asphalt pavement to the aged asphalt, and stir at 155℃ for 10 min at a stirring speed of 1000 r / min. Figure 4 As shown, BR-1 recycled asphalt was finally obtained.

[0044] Specifically, the amount of Bio-I high-performance thermal recycling agent added is 6% of the mass of the recycled old asphalt.

[0045] In this embodiment, unless otherwise specified, all raw materials used can be obtained commercially.

[0046] Example 2 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:2.26; The premixing temperature is 35℃, the stirring speed is 900 r / min, and the time is 10 min; The mass of the carboxyl-terminated polyisoprene liquid rubber is 5.61% of the total mass of the mixed oil phase; the mass of the antioxidant BHT is 0.5% of the total mass of the mixed oil phase; and the mass of the cocoagulant is 1% of the total mass of the mixed oil phase. The re-stirring temperature was 42℃, the stirring speed was 900r / min, and the time was 25min, finally producing Bio-Ⅰ high-performance hot recycling agent for asphalt pavement with the code BR-2.

[0047] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 160℃ to obtain BR-2 recycled asphalt.

[0048] The amount of Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement added is 3% of the mass of aged asphalt.

[0049] Example 3 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:1.94. The premixing temperature is 40℃, the stirring speed is 1000 r / min, and the time is 15min; The mass of the carboxyl-terminated polyisoprene liquid rubber is 5.36% of the total mass of the mixed oil phase; the mass of the antioxidant BHT is 2% of the total mass of the mixed oil phase; and the mass of the cocoagulant is 1.5% of the total mass of the mixed oil phase. The re-stirring temperature was 50℃, the stirring speed was 1000 r / min, and the time was 30 min, finally producing Bio-I high-performance hot recycling agent for asphalt pavement with the code BR-3.

[0050] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 165℃ to obtain BR-3 recycled asphalt.

[0051] The amount of Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement added is 8% of the mass of aged asphalt.

[0052] Example 4 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:1.72. The premixing temperature is 40℃, the stirring speed is 1000 r / min, and the time is 20 min; The mass of the carboxyl-terminated polyisoprene liquid rubber is 5.77% of the total mass of the mixed oil phase; the mass of the antioxidant BHT is 1.25% of the total mass of the mixed oil phase; and the mass of the cocoagulant is 2% of the total mass of the mixed oil phase. The re-stirring temperature was 45℃, the stirring speed was 900 r / min, and the time was 30 min, finally producing Bio-Ⅰ high-performance hot recycling agent for asphalt pavement with the code BR-4.

[0053] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 175℃ to obtain BR-4 recycled asphalt.

[0054] The Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement is added at a rate of 5% of the mass of aged asphalt.

[0055] Example 5 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:1.50. The premixing temperature was 33℃, the stirring speed was 850 r / min, and the time was 18 min. The mass of the carboxyl-terminated polyisoprene liquid rubber is 6.25% of the total mass of the mixed oil phase; the mass of the antioxidant BHT is 1.5% of the total mass of the mixed oil phase; and the mass of the cocoagulant is 3% of the total mass of the mixed oil phase. The re-stirring temperature was 48℃, the stirring speed was 950 r / min, and the time was 28 min, finally producing Bio-I high-performance hot recycling agent for asphalt pavement with the code BR-5.

[0056] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 170℃ to obtain BR-5 recycled asphalt.

[0057] The Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement is added at a rate of 7% of the mass of aged asphalt.

[0058] Example 6 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:1.50. The mass of the carboxyl-terminated polyisoprene liquid rubber is 8.16% of the total mass of the mixed oil phase; The final product was Bio-I high-performance hot recycling agent for asphalt pavement, designated BR-6.

[0059] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 160℃ to obtain BR-6 recycled asphalt.

[0060] Example 7 The steps of this embodiment are the same as those of the preparation method provided in Example 1, except that: In S2: The mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:1.50. The mass of the carboxyl-terminated polyisoprene liquid rubber is 10.0% of the total mass of the mixed oil phase; The final product was Bio-I high-performance thermal recycling agent for asphalt pavement, designated BR-7.

[0061] In S3: The Bio-Ⅰ high-performance hot recycling agent for asphalt pavement is blended with aged asphalt at high speed under 165℃ to obtain BR-7 recycled asphalt.

[0062] Specifically, in Examples 1-7, the specific mass fractions of the composite unsaturated bio-oil, petroleum-based vacuum residue, and carboxyl-terminated polyisoprene liquid rubber are shown in Table 1.

[0063] Table 1. Mass fraction and proportion of each component in Bio-Ⅰ high-performance thermal recycling agent for asphalt pavement. Comparative Example 1 (DB-1) This comparative example uses recycled asphalt without any added bio-based regenerators. The original waste asphalt sample is used as the control sample without any additional modification or recycling treatment, and is designated as DB-1.

[0064] Comparative Example 2 (DB-2) This comparative example uses No. 70 asphalt, designated DB-2, which meets the technical requirements for road petroleum asphalt in the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40—2004).

[0065] To verify the effectiveness of this invention, the technical performance of the Bio-Ⅰ high-performance hot recycling agent for asphalt pavement prepared in each embodiment was tested according to the "Technical Specification for Recycling of Highway Asphalt Pavement" (JTG / T 5521—2019), and the test results are shown in Table 2. According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the penetration, softening point and ductility of the recycled asphalt in each embodiment and comparative example were tested, and the test results are shown in Table 3, as follows.

[0066] Table 2 Technical Performance of Bio-I High-Performance Thermal Recycling Agent for Asphalt Pavements Note: RA-75 comes from the technical requirements for asphalt recycling agents in the "Technical Specification for Recycling of Highway Asphalt Pavement (JTG / T 5521—2019)".

[0067] Table 3 Technical performance of recycled asphalt and comparative asphalt in each embodiment As can be seen from the data in Table 2, 1) As shown in Examples 1-3, as the amount of composite unsaturated bio-oil increases, the viscosity ratio of the regenerator before and after the film oven test increases, while the viscosity at 60℃, density at 15℃, and mass change after the film oven test decrease. The flash point increases slightly, but the change is not significant and meets the specification requirements.

[0068] 2) As shown in Examples 3-5, with the increase of the amount of petroleum-based vacuum residue, the viscosity at 60°C, the content of saturated fraction, the content of aromatic fraction, the change in mass after the thin film oven test, the viscosity ratio before and after the thin film oven test, and the density at 15°C of the regenerator all show an increasing trend, while the flash point decreases slightly, but the change is not significant.

[0069] 3) As shown in Examples 5-7, as the amount of liquid rubber increases, the viscosity of the regenerator at 60°C and the density at 15°C both decrease. The viscosity ratio before and after the film oven test increases and then decreases. The flash point increases slightly. The mass change after the film oven test is very small.

[0070] It can be seen that at 60℃ or below, the chemical cross-linking reaction between the composite unsaturated bio-oil, liquid rubber, and petroleum-based vacuum residue, and the self-polymerization reaction of the unsaturated bio-oil, progress slowly and the degree of reaction is limited. The composite unsaturated bio-oil and liquid rubber mainly act as diluents (the cross-linking reaction principle between the unsaturated bonds of the raw tung oil and the liquid polybutadiene rubber is as follows). Figure 2As shown in the figure, reducing the viscosity of petroleum-based vacuum residue facilitates pipeline pumping and spraying operations, promotes uniform mixing with recycled aggregates, and facilitates the storage of recyclers, ensuring stable quality. At high temperatures, such as after a thin-film oven aging test (163±1℃, 5h), the chemical cross-linking reaction between the composite unsaturated bio-oil, liquid rubber, and petroleum-based vacuum residue, as well as the self-polymerization reaction of the composite unsaturated bio-oil, are intensified, leading to an increase in the viscosity of the recycler. This results in a larger viscosity ratio before and after the thin-film oven test, which also helps the recycler to bind aggregates, improves interfacial bonding performance, and synergizes with the thermal recycling process of asphalt pavement.

[0071] As can be seen from the data in Table 3, 1) As shown in Examples 1-3, with the increase of bio-oil content, the penetration decreases and the softening point increases. Due to the cross-linking effect of bio-oil with liquid rubber and vacuum residue, the recycled asphalt becomes more viscous, resulting in the penetration (25°C) of Example 3 being less than 60 (0.1 mm). 2) Referring to Examples 3-5, the reduction of vacuum residue content leads to an increase in penetration and a decrease in softening point. On the one hand, the reduction of vacuum residue content weakens the ability of olefin and hydrocarbon free radicals in vacuum residue to undergo addition reactions with bio-oil polymer chains. On the other hand, the reduction of vacuum residue content reduces the content of asphaltenes (mainly from vacuum residue) in recycled asphalt, resulting in a decrease in the high-temperature performance of asphalt. This makes the penetration (25°C) of Example 5 greater than 80 (0.1 mm) and the softening point less than 46.0°C. 3) As shown in Examples 5-7, as the amount of liquid rubber increases, the penetration decreases and the softening point increases, indicating that the liquid rubber mainly participates in the crosslinking reaction and improves the viscosity of recycled asphalt.

[0072] In summary, based on the index requirements of No. 70 asphalt in the current specifications, the recycled asphalt provided in Example 4 exhibits good road performance.

[0073] Furthermore, the more fully the reaction between the composite unsaturated bio-oil and the carboxyl-terminated polyisoprene and petroleum-based vacuum residue free radicals, the smaller the penetration of the recycled asphalt and the greater its softening. With the heating and fusion of the regenerator and recycled asphalt, the reaction between the composite unsaturated bio-oil and the carboxyl-terminated polyisoprene and petroleum-based vacuum residue free radicals is effectively promoted, facilitating the formation of a three-phase cross-linked structure of the composite unsaturated bio-oil, liquid rubber, and petroleum-based vacuum residue, significantly improving the performance and thermo-oxidative stability of the regenerator. Simultaneously, the composite unsaturated bio-oil, petroleum-based vacuum residue, and recycled asphalt are fully mixed, achieving complementary active functions of each component, restoring the original asphalt's component structure, delaying the continuous aging of the old asphalt, and significantly improving the interfacial compatibility and interfacial adhesion of the recycled asphalt. Therefore, the penetration, softening point, and ductility at 15℃ of the recycled asphalt are basically close to the technical requirements for No. 70 asphalt in the current specifications.

[0074] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0075] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A bio-based composite regenerator for in-situ thermal regeneration, characterized in that, It includes a complex of unsaturated bio-oils and petroleum-based vacuum residue, wherein the complex of unsaturated bio-oils includes tung oil, methyl ricinoleate, linseed oil and perilla oil.

2. A method for preparing a bio-based composite regenerator for in-situ thermal regeneration according to claim 1, characterized in that, Includes the following steps: S1. The raw tung oil, methyl ricinoleate, linseed oil and perilla oil are compounded in a specific mass ratio and then dehydrated to obtain a composite unsaturated bio-oil. S2. First, the composite unsaturated bio-oil and petroleum-based vacuum residue in a specific mass ratio are added to a reactor and premixed to form a homogeneous mixed oil phase. Then, liquid rubber, antioxidant and surfactant are added to the homogeneous mixed oil phase in sequence. After stirring again, Bio-I asphalt pavement high-performance thermal recycling agent is obtained.

3. The method for preparing a bio-based composite regenerator for in-situ thermal regeneration according to claim 2, characterized in that, In S2, the mass ratio of the composite unsaturated bio-oil to petroleum-based vacuum residue is 1:(1.5~2.5).

4. The method for preparing a bio-based composite regenerator for in-situ thermal regeneration according to claim 2, characterized in that, In S2, the liquid rubber accounts for 5-10% of the total mass of the homogeneous mixed oil phase, the antioxidant accounts for 0.5-2% of the total mass of the homogeneous mixed oil phase, and the surfactant accounts for 1-3% of the total mass of the homogeneous mixed oil phase.

5. The method for preparing a bio-based composite regenerator for in-situ thermal regeneration according to claim 2, characterized in that, In S2, the temperature of the premixing and stirring is 30~40℃, the stirring speed is 800~1000r / min, and the time is 10~20min.

6. The method for preparing a bio-based composite regenerator for in-situ thermal regeneration according to claim 2, characterized in that, In S2, the temperature for the second stirring is 40~50℃, the stirring speed is 800~1000r / min, and the time is 20~30min.

7. The application of a bio-based composite regenerator for in-situ thermal recycling based on any one of claims 1 to 6 and its preparation method in in-situ thermal recycling engineering of asphalt pavement.

8. The application of the bio-based composite regenerator for in-situ thermal regeneration according to claim 7, characterized in that, In the in-situ hot recycling of asphalt pavement, the amount of Bio-Ⅰ high-performance hot recycling agent added is 3~8% of the mass of aged asphalt, and the construction temperature is 155~175℃.

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