A polyphosphoric acid-sbs polymer composite modified bio-asphalt and asphalt mixture

Abstract

The present application belongs to the technical field of asphalt pavement materials, and particularly relates to a polyphosphoric acid-SBS polymer composite modified bio-asphalt and asphalt mixture. The polyphosphoric acid-SBS polymer composite modified bio-asphalt is prepared by a method comprising the following steps: heating and mixing base asphalt and a bio-modifier to obtain bio-asphalt; heating and mixing the bio-asphalt and SBS, and then heating and mixing the mixture with polyphosphoric acid to obtain a composite material; and then swelling and developing the composite material to obtain the polyphosphoric acid-SBS polymer composite modified bio-asphalt; the bio-modifier is a pine tar and / or a modified turpentine. The branched molecular chains in the bio-oil and the modified turpentine produce mechanical embedding, physical cross-linking and other effects, the benzene rings can produce conjugation effects to form a physical network structure, and the two can also be chemically cross-linked together in the form of phosphate ester bonds with polyphosphoric acid, thereby improving the comprehensive performance of the asphalt mixture.

Description

Technical Field

[0001] This invention belongs to the field of asphalt pavement materials technology, specifically a polyphosphate-SBS polymer composite modified bio-asphalt and asphalt mixture. Background Technology

[0002] Currently, the production of road asphalt relies on petroleum, a non-renewable resource. With limited reserves and rising extraction costs, this poses a potential challenge to the sustainable development of road construction. Therefore, finding alternatives to petroleum asphalt to reduce or eliminate its consumption is crucial for alleviating road construction's dependence on it.

[0003] Bio-oils, rich in polar functional groups and renewable, can be used to improve the low-temperature crack resistance and aging resistance of asphalt. However, most bio-asphalts exhibit poor high-temperature performance and water stability. Polyphosphoric acid (PPA), as a chemical modifier, offers advantages such as low cost and significant modification effects. PPA can react with functional groups in asphalt, promoting the conversion of resins into asphaltenes, thereby improving the high-temperature rheological properties of asphalt and enhancing its fatigue resistance. However, the incorporation of PPA may adversely affect the low-temperature properties of asphalt, especially at higher dosages, where the low-temperature ductility and crack resistance of asphalt will significantly decrease.

[0004] For example, Gao Junfeng et al., in their paper "Research on the Performance of Road Bio-asphalt and Mixtures," studied the effects of different blending ratios of biomass heavy oil on the road performance of asphalt mixtures. The study found that increasing the proportion of biomass heavy oil increased the penetration of bio-asphalt, decreased its softening point, and improved its ductility, while decreasing its high-temperature deformation resistance. However, it effectively improved its low-temperature crack resistance. Compared with the control group of No. 50 base asphalt, when the biomass heavy oil content was 10%, the low-temperature crack resistance and water stability of the asphalt mixture were significantly improved, and the adhesion performance was also greatly enhanced, while the high-temperature stability index showed a certain degree of decrease. Zhou Yuming et al., in their paper "Research on the Influence of PPA Composite Modification on Asphalt-Aggregate Adhesion and Water Stability," studied the effects of PPA composite modification on asphalt-aggregate adhesion and water stability. The results showed that with the addition of PPA modifier, the surface free energy of asphalt significantly increased, the adhesion work between asphalt and aggregate improved, the interaction ability was enhanced, and the water stability of the asphalt mixture was better. The addition of PPA slightly reduced the adhesion between SBS and SBR polymer-modified asphalt and aggregates, but significantly improved the overall water stability.

[0005] Therefore, using bio-oil to modify asphalt will lead to a decrease in the high-temperature performance of asphalt, while using PPA to modify asphalt will improve the water stability of asphalt, but will reduce the adhesion between asphalt and aggregate, resulting in a decrease in the crack resistance of asphalt. Summary of the Invention

[0006] To address the above problems, this invention provides a polyphosphate-SBS polymer composite modified bio-asphalt and asphalt mixture, which solves the problems that the high-temperature performance of asphalt decreases when bio-oil is used to modify asphalt, or the crack resistance of asphalt deteriorates when PPA is used to modify asphalt.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A polyphosphate-SBS polymer composite modified bio-asphalt is prepared by a method comprising the following steps: heating and mixing a base asphalt and a bio-modifier to obtain bio-asphalt; then heating and mixing the bio-asphalt and SBS, followed by heating and mixing with polyphosphate to obtain a composite material; and then swelling and developing the composite material to obtain the polyphosphate-SBS polymer composite modified bio-asphalt; wherein the bio-modifier is pine tar and / or turpentine modified material, and the chemical structure of the turpentine modified material is as follows:

[0009] .

[0010] Preferably, the mass ratio of the base asphalt, biomodifier, SBS and polyphosphoric acid is 100:8~12:3~4:0.8~1.2; the biomodifier is composed of pine tar and turpentine modified product, and the mass ratio of pine tar and turpentine modified product is 8~9:1~2.

[0011] Preferably, the base asphalt is 70# base asphalt.

[0012] Preferably, the SBS is a linear SBS.

[0013] Preferably, the temperature at which the base asphalt and the biomodifier are heated and mixed is 130~140℃.

[0014] Preferably, the temperature at which bio-asphalt and SBS are heated and mixed is 165~175℃.

[0015] Preferably, the temperature at which the polyphosphoric acid is heated and mixed is 165~175°C.

[0016] Preferably, the swelling and development of the composite material is achieved by allowing the composite material to stand at a temperature of 165~175℃ for 1~2 hours.

[0017] Preferably, the turpentine modified product is prepared as follows: 2,3-epoxypinene and 1,4-bis(3-aminopropyldimethylsilyl)benzene are mixed and reacted in a solvent under the catalysis of pyridine to obtain the turpentine modified product; the molar ratio of 2,3-epoxypinene and 1,4-bis(3-aminopropyldimethylsilyl)benzene is 2:1.

[0018] An asphalt mixture is composed of polyphosphate-SBS polymer-modified bio-asphalt and mineral aggregates as described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The polyphosphate-SBS polymer composite modified bio-asphalt of this invention is made from base asphalt, a biomodifier, SBS, and polyphosphate. During the preparation process, polyphosphate can form phosphate ester chemical bonds with the hydroxyl groups in the biomodifier; SBS can form a network structure in the asphalt, thereby effectively limiting the flow deformation of the asphalt at high temperatures and reducing water damage, thus enhancing the overall stability of the mixture; polyphosphate can work synergistically with SBS to form a more stable network structure in the modified asphalt, enabling the asphalt mixture to more effectively resist deformation at high temperatures; moreover, polyphosphate can improve the dispersibility of SBS and enhance the modification effect of SBS, thereby making the modified asphalt mixture exhibit better crack resistance under low-temperature conditions; and the addition of SBS and polyphosphate significantly increases the viscosity of the asphalt, thereby enhancing the adhesion between the asphalt and aggregates. The enhanced adhesion helps the asphalt mixture... In a water environment, bio-oil can better maintain structural integrity, thereby improving the water damage resistance of asphalt mixtures. Bio-oil can improve the deformation capacity of asphalt mixtures under low-temperature conditions, enabling them to undergo greater deformation under low-temperature stress without brittle fracture, thus improving their low-temperature mechanical properties. The branched chains of components such as turpentine and rosin in bio-oil can mechanically intercalate and physically cross-link with the branched molecular chains at both ends of the turpentine modifier. The benzene rings in components such as guaiacol, cresol, methylcresol, phenol, and o-ethylphenol in bio-oil can conjugate with the benzene rings in the turpentine modifier, forming a physical network structure that improves the stability of asphalt mixtures. Moreover, polyphosphoric acid can chemically cross-link with the hydroxyl groups in both the turpentine modifier and bio-oil in the form of phosphate ester bonds, further improving the stability, low-temperature crack resistance, and water damage resistance of asphalt mixtures. Attached Figure Description

[0021] Figure 1 This is the 1H NMR spectrum of the turpentine oil modified product prepared in this invention;

[0022] Figure 2 Infrared spectra of asphalt or modified asphalt in Embodiment 1 and Comparative Examples 1-4 of the present invention;

[0023] Figure 3 This is the gradation design diagram of the AC-13F type mixture in this invention;

[0024] Figure 4 This is a graph showing the relationship between the bulk density and the asphalt-aggregate ratio of the asphalt mixture prepared in Example 1 of this invention.

[0025] Figure 5 This is a graph showing the relationship between the stability of the asphalt mixture prepared in Example 1 of this invention and the asphalt-aggregate ratio.

[0026] Figure 6 This is a graph showing the relationship between the porosity and the asphalt-aggregate ratio of the asphalt mixture prepared in Example 1 of this invention.

[0027] Figure 7 This is a graph showing the relationship between the flow value and the asphalt-aggregate ratio of the asphalt mixture prepared in Example 1 of this invention.

[0028] Figure 8 This is a graph showing the relationship between the aggregate void ratio (VMA) and the asphalt-aggregate ratio in the asphalt mixture prepared in Example 1 of this invention.

[0029] Figure 9 This is a graph showing the relationship between the effective asphalt saturation (VFA) and the asphalt-aggregate ratio of the asphalt mixture prepared in Example 1 of this invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0031] The inventive concept of this invention is as follows: Since bio-asphalt contains a large number of light components and polar functional groups, combining bio-asphalt with PPA helps to improve the ionization degree of PPA and enhance its modification effect. However, while modifying bio-asphalt with PPA alone significantly increases its softening point, it does not significantly improve the adhesion and water stability of the bio-asphalt, resulting in PPA-modified bio-asphalt still failing to meet road performance requirements. SBS is a widely used and highly efficient asphalt modifier that can effectively improve the high and low temperature properties, durability, and fatigue resistance of asphalt. However, SBS has poor stability in asphalt, and SBS-modified asphalt is prone to segregation under high temperature conditions, affecting its long-term performance. Considering the potential synergistic effect between PPA, SBS, and bio-asphalt, this invention selects PPA / SBS for composite modification of bio-asphalt to compensate for the deficiencies in road performance, such as insufficient high-temperature stability and water stability of bio-asphalt.

[0032] The preparation methods of the turpentine oil modified products in Examples 4 and 5 are as follows:

[0033] 2,3-Epoxypine, 1,4-bis(3-aminopropyldimethylsilyl)benzene, pyridine, and toluene were added to a reaction vessel, heated to 75°C, and stirred for 8 hours. The mixture was then distilled under reduced pressure to remove toluene and pyridine, yielding a concentrate. This concentrate was purified by column chromatography using a mixed solvent of petroleum ether, ethyl acetate, and methanol (volume ratio 7:4:2) to obtain a pale yellow, viscous turpentine-modified product. The molar ratio of 2,3-epoxypine to 1,4-bis(3-aminopropyldimethylsilyl)benzene was 2:1, the mass of pyridine was 2% of the sum of the masses of 2,3-epoxypine and 1,4-bis(3-aminopropyldimethylsilyl)benzene, and the mass of toluene was four times the sum of the masses of 2,3-epoxypine and 1,4-bis(3-aminopropyldimethylsilyl)benzene. The 1H NMR spectrum of the turpentine-modified product is shown below. Figure 1 As shown, the chemical structure is as follows:

[0034] .

[0035] Example 1

[0036] The polyphosphate-SBS polymer composite modified bioasphalt of this embodiment is prepared by a method including the following steps:

[0037] (1) Heat the base asphalt to 135°C, then shear the base asphalt at 1000 r / min, slowly add bio-oil to the base asphalt, and stir at 135°C for 20 min to obtain bio-asphalt.

[0038] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 170°C for 30 min at a speed of 5000 r / min. Then add polyphosphoric acid and continue to stir at 170°C for 30 min at a speed of 5000 r / min to obtain a composite material. Then let the composite material stand at 170°C for 1 h to allow it to swell and develop, and eliminate residual bubbles to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt.

[0039] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the bio-oil is pine tar produced by Jiangxi Huajin New Materials Co., Ltd., whose raw material is pine sawdust. This bio-oil is a reddish-brown viscous liquid at room temperature; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid is provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, bio-oil, SBS, and polyphosphoric acid is 100:10:3.5:1.

[0040] Example 2

[0041] The polyphosphate-SBS polymer composite modified bioasphalt of this embodiment is prepared by a method including the following steps:

[0042] (1) Heat the base asphalt to 135°C, then shear the base asphalt at 1000 r / min, slowly add bio-oil to the base asphalt, and stir at 135°C for 20 min to obtain bio-asphalt.

[0043] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 170°C for 30 min at a speed of 5000 r / min. Then add polyphosphoric acid and continue to stir at 170°C for 30 min at a speed of 5000 r / min to obtain a composite material. Then let the composite material stand at 170°C for 1 h to allow it to swell and develop, and eliminate residual bubbles to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt.

[0044] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the bio-oil is pine tar produced by Jiangxi Huajin New Materials Co., Ltd., whose raw material is pine sawdust. This bio-oil is a reddish-brown viscous liquid at room temperature; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid is provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, bio-oil, SBS, and polyphosphoric acid is 100:8:3:0.8.

[0045] Example 3

[0046] The polyphosphate-SBS polymer composite modified bioasphalt of this embodiment is prepared by a method including the following steps:

[0047] (1) Heat the base asphalt to 135°C, then shear the base asphalt at 1000 r / min, slowly add bio-oil to the base asphalt, and stir at 135°C for 20 min to obtain bio-asphalt.

[0048] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 170°C for 30 min at a speed of 5000 r / min. Then add polyphosphoric acid and continue to stir at 170°C for 30 min at a speed of 5000 r / min to obtain a composite material. Then let the composite material stand at 170°C for 1 h to allow it to swell and develop, and eliminate residual bubbles to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt.

[0049] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the bio-oil is pine tar produced by Jiangxi Huajin New Materials Co., Ltd., whose raw material is pine sawdust. This bio-oil is a reddish-brown viscous liquid at room temperature; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid is provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, bio-oil, SBS, and polyphosphoric acid is 100:12:4:1.2.

[0050] Example 4

[0051] The polyphosphate-SBS polymer composite modified bioasphalt of this embodiment is prepared by a method including the following steps:

[0052] (1) Heat the base asphalt to 135°C, then shear the base asphalt at 1000 r / min, slowly add the turpentine modifier to the base asphalt, and stir at 135°C for 20 min to obtain bio-asphalt.

[0053] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 170°C for 30 min at a speed of 5000 r / min. Then add polyphosphoric acid and continue to stir at 170°C for 30 min at a speed of 5000 r / min to obtain a composite material. Then let the composite material stand at 170°C for 1 h to allow it to swell and develop, and eliminate residual bubbles to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt.

[0054] The base asphalt was 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the SBS was YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid was provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, turpentine modifier, SBS, and polyphosphoric acid was 100:10:3.5:1.

[0055] Example 5

[0056] The polyphosphate-SBS polymer composite modified bioasphalt of this embodiment is prepared by a method including the following steps:

[0057] (1) Heat the base asphalt to 135°C, then shear the base asphalt at a speed of 1000 r / min, and slowly add bio-oil and turpentine modifier to the base asphalt in sequence. Stir at 135°C for 20 min to obtain bio-asphalt.

[0058] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 170°C for 30 min at a speed of 5000 r / min. Then add polyphosphoric acid and continue to stir at 170°C for 30 min at a speed of 5000 r / min to obtain a composite material. Then let the composite material stand at 170°C for 1 h to allow it to swell and develop, and eliminate residual bubbles to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt.

[0059] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the bio-oil is pine tar produced by Jiangxi Huajin New Materials Co., Ltd., whose raw material is pine sawdust. This bio-oil is a reddish-brown viscous liquid at room temperature; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid is provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, bio-oil, turpentine modifier, SBS, and polyphosphoric acid is 100:8.5:1.5:3.5:1.

[0060] Comparative Example 1

[0061] The asphalt used in this comparative example is the base asphalt from Example 1.

[0062] Comparative Example 2

[0063] The modified asphalt of this comparative example was prepared by a method including the following steps: heating the base asphalt to 170°C, stirring continuously during the heating process, then slowly adding SBS, stirring at 5000 r / min at 170°C for 30 min; then letting it stand at 170°C for 1 h to eliminate residual air bubbles, thus obtaining the modified asphalt.

[0064] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which appears as a white porous solid at room temperature. The mass ratio of base asphalt to SBS is 100:3.5.

[0065] Comparative Example 3

[0066] The modified asphalt in this comparative example was prepared by a method including the following steps:

[0067] (1) Heat the base asphalt to 135°C, then shear the base asphalt at 1000 r / min, slowly add bio-oil to the base asphalt, and stir at 135°C for 20 min to obtain bio-asphalt.

[0068] (2) Heat the bio-asphalt to 170°C and stir continuously during the heating process. Then slowly add SBS and stir at 5000 r / min at 170°C for 30 min. Then let it stand at 170°C for 1 h to eliminate residual air bubbles and obtain modified asphalt.

[0069] The base asphalt is 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the bio-oil is pine tar produced by Jiangxi Huajin New Materials Co., Ltd., whose raw material is pine sawdust. This bio-oil is a reddish-brown viscous liquid at room temperature; the SBS is YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature. The mass ratio of base asphalt, bio-oil, and SBS is 100:10:3.5.

[0070] Comparative Example 4

[0071] The modified asphalt of this comparative example was prepared by a method including the following steps: heating the base asphalt to 170°C, stirring continuously during the heating process, then slowly adding SBS, and stirring at 5000 r / min at 170°C for 30 min; then adding polyphosphoric acid, and continuing to stir at 170°C at 5000 r / min for 30 min to obtain a composite material, and then letting the composite material stand at 170°C for 1 h to eliminate residual air bubbles, thus obtaining the modified asphalt.

[0072] The base asphalt was 70# base asphalt, produced by Hunan Baoli Asphalt Co., Ltd.; the SBS was YH-791 linear SBS manufactured by Baling Petrochemical Co., Ltd., which is a white porous solid at room temperature; and the polyphosphoric acid was provided by Maclean's reagent, which is a colorless, transparent, viscous liquid at room temperature. The mass ratio of base asphalt, SBS, and polyphosphoric acid was 100:3.5:1.

[0073] Experimental Example 1

[0074] This experiment was used to investigate the chemical groups in the asphalt of Example 1 and Comparative Examples 1-4, as well as the chemical reactions that occurred during the preparation process. Infrared spectroscopy analysis was performed on the asphalt or modified asphalt of Example 1 and Comparative Examples 1-4, and the results are as follows: Figure 2 As shown. The asphalt in Comparative Example 1 is named base asphalt, the modified asphalt in Comparative Example 2 is named bio-asphalt, the modified asphalt in Comparative Example 3 is named PPA-modified bio-asphalt, and the modified asphalt in Example 1 is named PPA / SBS composite modified bio-asphalt. The measurement wavelength for infrared spectroscopy analysis was the mid-infrared region (4000~400cm). -1 The scanning frequency is 32 / min.

[0075] Depend on Figure 2 It can be seen that the infrared spectra of the four types of asphalt are at 2920 cm⁻¹-1 2850cm -1 1455cm -1 1375cm -1 812cm -1 724cm -1 Similar characteristic peaks appeared nearby. Among them, 2920cm -1 and 2850cm -1 The nearby absorption peaks correspond to the stretching vibrations of methylene (-CH2) and alkane (CH), respectively, indicating the presence of a large number of saturated hydrocarbon compounds in the asphalt. (1455 cm⁻¹) -1 The nearby absorption peaks are due to either the antisymmetric bending vibration of -CH3 or the antisymmetric and symmetric bending vibration of -CH2, indicating the presence of lipid compounds in the asphalt. (1375 cm⁻¹) -1 The presence of in-plane bending vibrations of the methyl group (—CH3) nearby further confirms the presence of lipid compounds in the asphalt. 812cm -1 724cm -1 The nearby absorption peaks correspond to the CH bending vibration and COS symmetric stretching on the benzene ring, indicating that the asphalt contains aromatic hydrocarbons and possible sulfide structures.

[0076] The infrared spectrum of bio-asphalt contains all the characteristic peaks of the base asphalt, indicating that the chemical composition of bio-oil and base asphalt is similar. The addition of bio-oil did not significantly change the basic chemical structure of the asphalt, but it may have increased the content of certain functional groups. Comparison of the infrared spectra of PPA-modified bio-asphalt, PPA / SBS composite-modified bio-asphalt, and bio-asphalt shows that the infrared spectra of PPA-modified bio-asphalt and PPA / SBS composite-modified bio-asphalt are concentrated at 1205 cm⁻¹. -1 And 1000cm -1 The appearance of a new absorption peak nearby indicates a chemical reaction between PPA and bio-asphalt. Specifically, the peak at 1205 cm⁻¹... -1 The nearby absorption peaks reflect the stretching vibrations of the P=O double bonds in the phosphate ester, indicating that the bioasphalt and PPA underwent an esterification reaction to form phosphate ester bonds. The 1000cm⁻¹ peak... -1 The nearby absorption peaks are caused by the antisymmetric stretching of POC in the phosphate ester formed after the reaction of bioasphalt and PPA. These results indicate that during the preparation of modified asphalt, the phosphate groups in polyphosphoric acid can undergo phosphorylation with the hydroxyl groups in bioasphalt to form chemical bonds.

[0077] Experimental Example 2

[0078] This experimental example was used to evaluate the elastic recovery and low-temperature crack resistance of the asphalt in Examples 1, 4-5, and Comparative Examples 1-4. Multi-stress creep recovery (MSCR) tests and low-temperature bending beam rheological tests were conducted on the asphalt or modified asphalt in Examples 1, 4-5, and Comparative Examples 1-4, respectively. The MSCR test was used to assess the cumulative deformation capacity of asphalt under repeated loading and unloading conditions. The specific test method is as follows: According to the standard JTG E20―2011 (T0610-2011), the asphalt samples were subjected to short-term aging using the Rotating Thin Film Heater (RTFOT) test. Then, the short-term aged asphalt samples were tested using a dynamic shear apparatus. The MSCR test used a 25mm rotor with a 1mm gap, a test temperature of 64℃, and an applied stress of 3.2kPa to simulate the effect of heavy traffic on asphalt. The test cycle consisted of 1s of stress loading followed by 9s of load removal, and was repeated for ten cycles. The creep recovery rate R of the asphalt was obtained from the test. The low-temperature bending beam rheological test is used to evaluate the low-temperature performance of asphalt. According to the standard JTG E20—2011 (T0627-2011), the creep rate m value of asphalt beam samples at -24℃ is tested and calculated using a bending beam rheometer. The test and calculation method is as follows:

[0079]

[0080]

[0081] Where: S(t) is the creep stiffness over time, in MPa; P is the applied dead load, in mN; L is the span of the beam, in mm; b is the beam width, in mm; h is the beam height, in mm; ∆(t) is the deflection at time t, in mm.

[0082] The test and calculation results of creep recovery rate R and creep rate m of the asphalt in Examples 1, 4-5 and Comparative Examples 1-4 are shown in Table 1.

[0083] Table 1. Test results of elastic recovery capacity and low-temperature crack resistance of asphalt.

[0084]

[0085] Creep recovery rate R represents the elastic recovery ability of asphalt after repeated loading, reflecting the degree to which asphalt can return to its original state after the load is removed. A larger R value indicates a higher proportion of elastic deformation that the asphalt can recover after unloading, less residual permanent deformation, and stronger resistance to rutting. Table 1 shows that under a high load level of 3.2 kPa, the elastic recovery of the asphalt in Comparative Example 1 is 0, indicating extremely poor elastic recovery ability of the base asphalt at this load level. Compared with the asphalt in Comparative Example 1, the R values ​​of the modified asphalts in Comparative Examples 2, 3, 4, Example 1, Example 4, and Example 5 increased by 18.51%, 15.44%, 46.62%, 42.95%, 41.87%, and 76.42%, respectively, indicating that the addition of SBS, turpentine modifiers, and polyphosphoric acid can significantly improve the elastic recovery ability of asphalt and enhance its high-temperature performance. Compared to the modified asphalts of Comparative Examples 2 and 3 without added polyphosphoric acid, the R-values ​​of the modified asphalts of Comparative Example 4 and Example 1 were significantly improved. This indicates that the incorporation of polyphosphoric acid improved the resistance to permanent deformation and elastic recovery of the modified asphalt. This is because polyphosphoric acid can work synergistically with SBS to optimize the spatial distribution of SBS in the asphalt, improve the modification effect of SBS, and enhance the intermolecular forces and network structure of the asphalt. Asphalt can more effectively absorb and release energy after being subjected to external forces, thus exhibiting stronger elastic recovery. Bio-oil had a negative impact on the elastic recovery of asphalt. The creep recovery rates of the modified asphalts of Comparative Example 3 and Example 1 were lower than those of the modified asphalts of Comparative Examples 2 and 4 without added bio-oil. This is because the addition of bio-oil introduced more lightweight components into the asphalt. These components have lower molecular weights and weaker intermolecular forces, which weaken the elastic network structure of the asphalt, reduce its elastic recovery, and thus lead to a decrease in the high-temperature performance of the modified asphalt. When turpentine modifiers and bio-oils are used simultaneously, the branched chains of turpentine and rosin in the bio-oil can mechanically intercalate and physically cross-link with the branched molecular chains at both ends of the turpentine modifiers. The benzene rings in components such as guaiacol, cresol, methylcresol, phenol, and o-ethylphenol in the bio-oil can conjugate with the benzene rings in the turpentine modifiers. Polyphosphoric acid can form phosphate ester bonds with the hydroxyl groups in the turpentine modifiers and bio-oils, resulting in chemical cross-linking. These physicochemical effects effectively enhance the intermolecular forces of asphalt, thereby improving its elastic recovery ability.

[0086] Creep rate *m* represents the rate at which the stiffness modulus changes with time. An increase in the value of *m* indicates a faster rate of stress release in asphalt under low-temperature conditions, thus reducing the time for stress accumulation within the material and helping to reduce the likelihood of asphalt cracking. Table 1 shows that compared to the modified asphalts of Comparative Examples 2 and 4 without added bio-oil, the added bio-oil significantly increases the *m* value of the modified asphalts of Comparative Example 3 and Example 1. This indicates that introducing bio-oil with a higher content of lightweight components into asphalt can significantly improve its low-temperature performance. This is because the introduction of lightweight components reduces the viscosity of the asphalt, enhancing its flowability under low-temperature conditions. The asphalt can better resist temperature stress through deformation, thereby reducing the formation of pavement cracks. Compared to Comparative Example 2, the m-values ​​of the modified asphalts in Comparative Examples 3 and 4 increased, indicating that the addition of bio-oil and polyphosphate modifiers can improve the low-temperature performance of SBS-modified asphalt. This is because not only does bio-oil itself improve the low-temperature performance of asphalt, but the addition of bio-oil also increases the amount of lightweight components in the asphalt, thus promoting the swelling and development of SBS in the asphalt and improving the modification effect of SBS. Asphalt can better resist cracking and deformation under low-temperature conditions. Polyphosphate can improve the compatibility between SBS and asphalt, increase the dispersion of SBS in the asphalt, and also enhance the modification effect of SBS, thereby enhancing the low-temperature performance of the modified asphalt. Compared to the modified asphalts of Comparative Examples 3 and 4, the modified asphalt of Example 1 exhibits better low-temperature performance. This is because an esterification reaction occurred between polyphosphoric acid and bio-asphalt. This chemical reaction promotes the formation of a more complex and stable three-dimensional network structure between the polyphosphoric acid / SBS composite modified bio-asphalt molecules. The formation of this structure allows the asphalt to better disperse stress under low-temperature conditions, which not only improves the flexibility of the asphalt under low-temperature conditions but also further enhances its crack resistance, enabling it to better resist cracking and deformation in low-temperature environments. Furthermore, the turpentine modifier and bio-oil can achieve mechanical intercalation and physical cross-linking through branched molecular chains, conjugation through benzene rings, and chemical cross-linking through phosphate ester bonds, thereby improving the flexibility and crack resistance of the asphalt under low-temperature conditions.

[0087] Experimental Example 3

[0088] This experiment was used to determine the optimal asphalt-aggregate ratio for preparing asphalt mixtures in Examples 1, 4-5, and Comparative Examples 1-4. The coarse and fine aggregates used in the preparation of the asphalt mixtures were basalt, and the mineral powder was limestone. The performance parameters of the coarse aggregate are shown in Table 2, the performance parameters of the fine aggregate are shown in Table 3, and the performance parameters of the mineral powder are shown in Table 4. The aggregate gradation adopted was AC-13F type fine-grained dense gradation. The gradation design of the AC-13F type mixture is shown in Table 5. Figure 3 As shown.

[0089] Table 2 Performance parameters of coarse aggregate

[0090]

[0091] Table 3 Performance parameters of fine aggregates

[0092]

[0093] Table 4 Performance parameters of mineral materials

[0094]

[0095] Table 5 AC-13F Grading Design

[0096]

[0097] Taking the optimal asphalt-aggregate ratio in the preparation of asphalt mixtures in Example 1 as an example, the method for determining the optimal asphalt-aggregate ratio is as follows: Five asphalt-aggregate ratios of 4.5%, 5.0%, 5.5%, 6.0%, and 6.5% were selected. According to the standard JTG E20-2011 (T0702), five Marshall specimens were prepared for each asphalt-aggregate ratio. The test results are shown in Table 6. Based on the test results in Table 6, a graph showing the relationship between bulk density, stability, void ratio, flow value, aggregate void ratio (VMA), and effective asphalt saturation (VFA) and the asphalt-aggregate ratio was plotted. The results are shown below. Figure 4-9 As shown.

[0098] Table 6 Results of the Marshall Test

[0099]

[0100] From Table 6 and Figure 4-9 It can be seen that the maximum bulk density, maximum stability, target void ratio (or median range), and median range of asphalt saturation of the asphalt mixture prepared using the asphalt of Example 1 correspond to asphalt-aggregate ratios of a1=5.2%, a2=5.4%, a3=5.4%, and a4=5.3%, respectively. The optimal asphalt-aggregate ratio of the asphalt mixture is OAC1=5.33%. The calculation method for OAC1 is as follows:

[0101] .

[0102] The MS, FL, VV, and VFA indicators of the mixture all meet the technical standards for the asphalt-aggregate ratio range OAC. min and OAC max The average value is taken as OAC2, where OAC min =4.6%, OAC max =6.5%, OAC2=5.55%, the calculation method of OAC2 is as follows:

[0103] .

[0104] The median of OAC1 and OAC2 is taken as the optimal oil-stone ratio OAC, with OAC=5.44%. The calculation method for OAC is as follows:

[0105] .

[0106] Calculations showed that the optimal asphalt-aggregate ratio for the modified asphalt in Example 1 was 5.44%. Similarly, using the same method, the optimal asphalt-aggregate ratios for the modified asphalt in Example 4, Example 5, and Comparative Example 1 were determined to be 5.34%, 5.39%, 4.83%, 5.31%, 5.22%, and 5.57%, respectively.

[0107] Experiment Example 4

[0108] High-temperature stability of asphalt mixtures refers to the ability of asphalt pavement to maintain its structural integrity and continue to function normally under repeated vehicle loads at high temperatures. It directly relates to the service life and driving safety of asphalt pavement under high-temperature conditions. The rutting test can intuitively simulate the actual driving environment of roads under high-temperature conditions. This test applies repeated loads to asphalt mixture samples, observes and records the deformation of the samples under load, and thus quantitatively evaluates the rutting resistance of the mixture. Its main evaluation index is dynamic stability (DS), which represents the number of standard axle loads that the asphalt mixture can withstand to produce 1 mm of deformation under high-temperature conditions. The higher the DS value of the asphalt mixture, the stronger its high-temperature rutting resistance, and the less likely the asphalt pavement is to rub under high temperature and repeated loads.

[0109] Based on the optimal asphalt-aggregate ratio determined in Experiment 3, this experimental example prepares rutted slab specimens (300mm×300mm×50mm) according to standard JTG E20-2011 (T0703). The specimens are then placed at room temperature for 48 hours, followed by curing at 60℃ for 6 hours in a rutting apparatus to simulate the effect of high-temperature environment on the performance of the rutted slab specimens. The rutting test is conducted according to standard JTG E20-2011 (T0719), with a temperature of 60℃, a wheel pressure of 0.7MPa, a load of 780N, and a test wheel reciprocating speed of 42 times / min. The deformation DS of the rutted slab specimens at 45min and 60min is calculated using the following formula:

[0110]

[0111] Where: DS is dynamic stability, times / mm; d1 is the deformation at compaction time t1min, mm; d2 is the deformation at compaction time t2min, mm; N is compaction speed, 42 times / min; C1 and C2 are the testing machine type coefficient and specimen coefficient, respectively, both with a value of 1.0.

[0112] The high-temperature stability test results of asphalt mixtures prepared using asphalt from Examples 1, 4-5 and Comparative Examples 1-4 are shown in Table 7.

[0113] Table 7 Calculation results of high-temperature stability test of asphalt mixtures

[0114]

[0115] As shown in Table 7, the dynamic stability of the asphalt mixture corresponding to the modified asphalt in Comparative Example 2 was 244.1% higher than that of the asphalt mixture corresponding to the asphalt in Comparative Example 1, and it met the requirement of dynamic stability of not less than 2800 cycles / mm in the specification. This indicates that the incorporation of SBS significantly improved the high-temperature rutting resistance of the asphalt mixture. This is because SBS can form a network structure in the asphalt, thereby effectively limiting the flow deformation of the asphalt at high temperatures and enhancing the overall stability of the mixture. After adding polyphosphoric acid, compared with the modified asphalts of Comparative Example 2 and Comparative Example 3 without the addition of polyphosphoric acid, the high-temperature rutting resistance of the asphalt mixtures corresponding to the modified asphalt in Comparative Example 4 and Example 1 was further enhanced under the combined effect of polyphosphoric acid / SBS. This is because polyphosphoric acid can work together with SBS to form a more stable network structure in the modified asphalt, and the asphalt mixture can more effectively resist deformation at high temperatures. Compared to the modified asphalt of Comparative Examples 2 and 4 without added bio-oil, the addition of bio-oil reduced the dynamic stability of the asphalt mixtures corresponding to the modified asphalt of Comparative Example 3 and Example 1 by 34.7% and 21.3%, respectively. Furthermore, the dynamic stability of the asphalt mixture corresponding to the modified asphalt of Comparative Example 3 could not meet the requirement of 2800 cycles / mm in the specification. This indicates that the addition of bio-oil reduced the high-temperature rutting resistance of the asphalt mixture. This is because the addition of bio-oil increases the content of lightweight components in the asphalt, softens the asphalt texture, and makes the asphalt mixture more prone to flow deformation under the repeated action of high-temperature environment and vehicle load, thereby weakening the high-temperature rutting resistance of the asphalt mixture. Although the dynamic stability of the asphalt mixture corresponding to the modified asphalt in Example 1 was affected by bio-oil, it still met the specification requirements and was better than that of the asphalt mixtures corresponding to the modified asphalt in Comparative Examples 2 and 3. This indicates that the synergistic effect of polyphosphoric acid and SBS can effectively offset the adverse effects of bio-oil on the high-temperature rutting resistance of asphalt mixtures. As a result, the polyphosphoric acid / SBS composite modified bio-asphalt mixture can still maintain good structural stability and deformation resistance under high-temperature conditions, exhibiting superior high-temperature performance.

[0116] Furthermore, compared to Example 1, when turpentine modifiers are used to replace bio-oil, the larger molecular weight of the turpentine modifiers, containing rigid benzene rings and silicon atoms, and cross-linking through the reaction of hydroxyl groups with polyphosphoric acid, will improve the thermal stability of the asphalt mixture to a certain extent. Compared to Example 4, when both turpentine modifiers and bio-oil are used, the branched chains of turpentine, rosin, and other components in the bio-oil can mechanically intercalate and physically cross-link with the branched molecular chains at both ends of the turpentine modifiers. Additionally, the benzene rings in components such as guaiacol, cresol, methylcresol, phenol, and o-ethylphenol in the bio-oil can conjugate with the benzene rings in the turpentine modifiers, forming a physical network structure that improves the thermal stability of the asphalt mixture. Moreover, polyphosphoric acid can chemically cross-link with the hydroxyl groups in both the turpentine modifiers and the bio-oil through phosphate ester bonds, further enhancing the thermal stability of the asphalt mixture.

[0117] Experimental Example 5

[0118] The low-temperature crack resistance of asphalt mixtures refers to the ability of asphalt pavements to resist thermal shrinkage cracking caused by temperature drops. Asphalt mixtures used in low-temperature regions must possess good low-temperature crack resistance because the physical properties of asphalt materials change significantly at low temperatures. Asphalt becomes hard and brittle, and its flexibility and ductility decrease considerably. Under these conditions, asphalt mixtures are more prone to shrinkage due to temperature changes, leading to the accumulation of internal stress. When the stress generated by thermal shrinkage exceeds the tensile strength of the asphalt mixture, cracks will appear on the pavement. The appearance of pavement cracks not only affects the smoothness of the road and driving comfort but also further reduces the service life of the pavement.

[0119] To evaluate the low-temperature crack resistance of asphalt mixtures, this experimental example prepared an asphalt mixture based on the optimal asphalt-aggregate ratio determined in Experiment 3, and conducted a low-temperature bending beam test according to specification JTG E20-2011 (T 0715). The asphalt mixture beam specimens used in the test had dimensions of (250mm × 30mm × 35mm), the test temperature was -10℃ ± 0.5℃, and the loading rate was 50mm / min. The flexural tensile strength R was obtained through the test. B and maximum bending tensile strain ɛ B Then calculate the bending stiffness modulus S. B The calculation method is as follows:

[0120]

[0121]

[0122]

[0123] In the formula: R B ε is the tensile strength of the specimen at failure (MPa); B The maximum flexural tensile strain at specimen failure is (με); S B 1. B is the flexural stiffness modulus at specimen failure (MPa); 2. B is the width of the specimen cross-section (mm); 3. H is the height of the specimen cross-section (mm); 4. L is the span of the specimen (mm); 5. P is the flexural stiffness modulus at specimen failure (MPa); 6. P is the width of the specimen cross-section (mm); 7. H is the height of the specimen cross-section (mm); 8. L is the span of the specimen (mm); 9. P is the flexural stiffness modulus at specimen failure (MPa); 10. P is the flexural stiffness modulus at specimen failure (MPa); 11. P is the flexural stiffness modulus at specimen failure (MPa); 12. P is the flexural stiffness modulus at specimen failure (MPa); 13. P is the flexural stiffness modulus at specimen failure (MPa); 14. P is the flexural stiffness modulus at specimen failure (MPa); 15. P is the flexural stiffness modulus at specimen failure (MPa); 16. P is the flexural stiffness modulus at specimen failure (MPa); 17. P is the flexural stiffness modulus at specimen failure (MPa); 18. P is the flexural stiffness modulus at specimen failure (MPa); 19. P is the flexural stiffness modulus at specimen failure (MPa); 10. P is the flexural stiffness modulus at specimen failure (MPa); 10. H is the flexural stiffness modulus at specimen cross-section (mm); 12. L is the flexural stiffness modulus at specimen failure (mm); 13. P is the flexural stiffness modulus at specimen failure (mm); 14. P is the flexural stiffness modulus at specimen failure (mm); 15. P is the flexural stiffness modulus at specimen failure (mm); 16. P is the flex B d is the maximum load (N) at which the specimen fails; d is the mid-span deflection (mm) at which the specimen fails.

[0124] The results of the low-temperature crack resistance test of asphalt mixtures prepared using asphalt from Examples 1, 4-5 and Comparative Examples 1-4 are shown in Table 8.

[0125] Table 8 Calculation results of low-temperature crack resistance test of asphalt mixture

[0126]

[0127] As shown in Table 8, compared to the asphalt in Comparative Example 1, the R of the modified asphalt mixture in Comparative Example 2 after adding SBS is significantly lower. B value and ɛ B The increased values ​​indicate that the incorporation of SBS enhances the low-temperature crack resistance of the asphalt mixture. Compared to the modified asphalt of Comparative Examples 2 and 3 without polyphosphate, the asphalt mixtures corresponding to the modified asphalt of Comparative Example 4 and Example 1 exhibit significantly higher R values. B value and ɛ B The increased values ​​indicate that the combined use of polyphosphoric acid / SBS has a better effect on improving the low-temperature crack resistance of asphalt mixtures than the use of SBS modifier alone. This is mainly because the addition of polyphosphoric acid further optimizes the dispersibility of SBS and improves the modification effect of SBS, thus enabling the modified asphalt mixture to exhibit superior crack resistance under low-temperature conditions. Compared with the modified asphalt of Comparative Examples 2 and 4, the R values ​​of the asphalt mixtures corresponding to the modified asphalt of Comparative Example 3 and Example 1 after incorporating bio-oil are significantly higher. B andɛ B The increase in all values ​​indicates that the asphalt mixture has an enhanced ability to withstand loads and deformations at low temperatures. This is because the addition of bio-oil improves the deformation capacity of the asphalt mixture under low-temperature conditions, enabling it to undergo greater deformation under low-temperature stress without brittle fracture. Therefore, the asphalt mixture can better resist thermal shrinkage stress in low-temperature environments, thereby improving its low-temperature mechanical properties.

[0128] Furthermore, compared to Examples 1 and 4, when both turpentine modifier and bio-oil are used simultaneously, the branched chains of turpentine and resin in the bio-oil can interact with the branched molecular chains at both ends of the turpentine modifier through mechanical intercalation and physical cross-linking. Additionally, the benzene rings in components such as guaiacol, cresol, methylcresol, phenol, and o-ethylphenol in the bio-oil can interact with the benzene rings in the turpentine modifier through conjugation. Furthermore, polyphosphoric acid can chemically cross-link with the hydroxyl groups in the turpentine modifier and bio-oil through phosphate ester bonds. These factors effectively improve the R-value of asphalt mixtures. B andɛ B This improves the low-temperature crack resistance of asphalt.

[0129] Experimental Example 6

[0130] When the water stability of an asphalt mixture is poor, the asphalt film is more easily peeled off from the aggregate surface due to the influence of water. This causes the aggregate to lose the binding effect of the asphalt, and asphalt pavement begins to experience particle loss. Furthermore, as peeling and particle loss intensify, the internal structure of the mixture gradually becomes loose, and the overall load-bearing capacity decreases. Under repeated vehicle loads, this further exacerbates the deterioration of the asphalt mixture structure, leading to potholes and other defects, affecting driving safety and the service life of the pavement.

[0131] To examine the water stability of the asphalt mixtures prepared from the asphalt in each embodiment and comparative example, this experimental example prepared asphalt mixtures based on the optimal asphalt-aggregate ratio determined in Experiment 3, and subjected the asphalt mixtures to immersion Marshall tests and freeze-thaw splitting tests.

[0132] The immersion Marshall test quantifies the water stability of asphalt mixture samples by measuring their Marshall stability before and after immersion and calculating the ratio between the two. The main evaluation index is the residual stability MS0. The larger the MS0, the better the water stability of the asphalt mixture. The test is conducted according to the standard JTG E20-2011 (T 0709). The specimens are divided into two groups. One group is kept in a constant temperature water bath at 60℃ for 30 min, and its stability MS is measured. The other group is kept in a constant temperature water bath at 60℃ for 48 h, and its immersion stability MS1 is measured. Then the residual stability MS0 is calculated as MS0 = MS1 / MS × 100%.

[0133] The main evaluation index of the freeze-thaw splitting test is the residual strength ratio (TSR), which quantifies the water damage resistance of the mixture by comparing the splitting strength of the specimens before and after freeze-thaw cycles. The test was conducted according to standard JTG E20-2011 (T0729). The specimens were divided into two groups. One group was placed in a constant temperature water bath at 25℃ for 2 hours before testing, and then its splitting strength R was calculated. T1Another group of specimens first underwent a vacuum saturation test, then were refrigerated at -18℃ for 16 hours, then placed in a constant temperature water bath at 60℃ for 24 hours, and finally placed in a constant temperature water bath at 25℃ for 2 hours before testing. Their splitting tensile strength R was then calculated. T2 Finally, the residual strength ratio (TSR) of the mixture specimens is calculated using the following method:

[0134]

[0135]

[0136]

[0137] In the formula: R T1 R T2 P represents the splitting tensile strength, in MPa; T1 P T2 The maximum load is N; , 1 represents the average splitting tensile strength, MPa; h1 and h2 represent the height of the specimen, mm; TSR represents the freeze-thaw splitting tensile strength ratio, %.

[0138] The calculation results of the immersion Marshall test of the asphalt mixtures prepared using the asphalt of each embodiment and comparative example are shown in Table 9, and the calculation results of the freeze-thaw splitting test are shown in Table 10.

[0139] Table 9. Calculation results of Marshall test for immersion of asphalt mixtures

[0140]

[0141] Table 10 Calculation results of freeze-thaw splitting test of asphalt mixture

[0142]

[0143] Table 9 shows that after 48 hours of immersion in water, the stability of each asphalt mixture decreased to varying degrees, indicating that water damage occurred. Specifically, the residual stability of the asphalt mixtures corresponding to the modified asphalt in Comparative Examples 2 and 4 was significantly improved compared to that of the asphalt mixture in Comparative Example 1. This indicates that the addition of SBS and polyphosphate enhanced the water damage resistance of the asphalt mixtures. This is because the addition of SBS and polyphosphate significantly increased the viscosity of the asphalt, thereby enhancing the adhesion between the asphalt and aggregates. Increased adhesion helps the asphalt mixture maintain its structural integrity better in a water environment, thus improving its water damage resistance. Compared to the modified asphalt in Comparative Examples 2 and 4, the residual stability of the asphalt mixtures corresponding to the modified asphalt in Comparative Example 3 and Example 1 decreased after the addition of bio-oil. This indicates that bio-oil had a negative effect on the water stability of the mixtures. This is because bio-oil reduced the consistency of the asphalt, weakened the bond between the asphalt and aggregates, and made the mixtures more susceptible to water damage. After the addition of polyphosphoric acid, the improvement in residual stability of the asphalt mixture corresponding to the modified asphalt in Example 1 compared to the modified asphalt in Comparative Example 3 was greater than the improvement in residual stability of the asphalt mixture corresponding to the modified asphalt in Comparative Example 4 compared to the modified asphalt in Comparative Example 2. This is because an esterification reaction occurred between polyphosphoric acid and bio-asphalt. The esterification reaction made the molecular structure between asphalt molecules more complex and stable, which not only improved the mechanical properties of the asphalt mixture, but also enhanced the water damage resistance of the mixture. Compared to Examples 1 and 4, Example 5 uses both turpentine modifier and bio-oil. Because the branched chains of turpentine and rosin in the bio-oil can interact with the branched molecular chains at both ends of the turpentine modifier through mechanical intercalation and physical cross-linking, and because the benzene rings in guaiacol, cresol, methylcresol, phenol, and o-ethylphenol in the bio-oil can interact with the benzene rings in the turpentine modifier through conjugation, and because polyphosphoric acid interacts with the hydroxyl groups in the turpentine modifier and bio-oil through chemical cross-linking via phosphate ester bonds, although bio-oil has a negative effect on the water stability of the mixture, the water damage resistance of the asphalt mixture is significantly improved when used simultaneously with turpentine modifier and polyphosphoric acid.

[0144] Table 10 shows that the splitting tensile strength of all mixtures decreased after freeze-thaw cycles, indicating water damage to the asphalt mixtures. Consistent with the results of the immersion Marshall test, the freeze-thaw splitting test results further illustrate the significant role of the combined use of polyphosphate and SBS in improving the water stability of asphalt mixtures. Although the incorporation of bio-oil improved the low-temperature crack resistance of the mixture, it reduced the water stability of the mixture, making the asphalt pavement more prone to spalling and loosening in a water environment. However, when bio-oil, turpentine modifier, and polyphosphate are used simultaneously, the mechanical interlocking and physical cross-linking between branched molecular chains within the system, the conjugation between benzene rings, the chemical cross-linking of phosphate groups, and the hydrophobic silicon atoms in the molecular chains can significantly improve the splitting tensile strength and water damage resistance of the mixture.

[0145] It should be noted that, in this document, the terms "comprising," "including," and any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A polyphosphate-SBS polymer composite modified bio-asphalt, characterized in that, The bio-asphalt is prepared by a method comprising the following steps: heating and mixing a base asphalt and a biomodifier to obtain bio-asphalt; heating and mixing the bio-asphalt and SBS, and then heating and mixing them with polyphosphoric acid to obtain a composite material; then swelling and developing the composite material to obtain polyphosphoric acid-SBS polymer composite modified bio-asphalt; wherein the biomodifier is a turpentine modifier or the biomodifier is composed of pine tar and turpentine modifier in a mass ratio of 8~9:1~2, and the mass ratio of the base asphalt, biomodifier, SBS and polyphosphoric acid is 100:8~12:3~4:0.8~1.2; the chemical structure of the turpentine modifier is as follows: .

2. The polyphosphate-SBS polymer composite modified bio-asphalt according to claim 1, characterized in that, The base asphalt is 70# base asphalt.

3. The polyphosphate-SBS polymer composite modified bio-asphalt according to claim 1, characterized in that, The SBS is a linear SBS.

4. The polyphosphate-SBS polymer composite modified bio-asphalt according to any one of claims 1-3, characterized in that, The temperature for heating and mixing the base asphalt and biomodifier is 130~140℃.

5. The polyphosphate-SBS polymer composite modified bio-asphalt according to any one of claims 1-3, characterized in that, The temperature for heating and mixing bio-asphalt and SBS is 165~175℃.

6. The polyphosphate-SBS polymer composite modified bio-asphalt according to any one of claims 1-3, characterized in that, The temperature at which the polyphosphoric acid is heated and mixed is 165~175℃.

7. The polyphosphate-SBS polymer composite modified bio-asphalt according to any one of claims 1-3, characterized in that, The swelling and development of the composite material involves letting it stand at a temperature of 165~175℃ for 1~2 hours.

8. The polyphosphate-SBS polymer composite modified bio-asphalt according to any one of claims 1-3, characterized in that, The turpentine modified product is prepared as follows: 2,3-epoxypine and 1,4-bis(3-aminopropyldimethylsilyl)benzene are mixed and reacted in a solvent under the catalysis of pyridine to obtain the turpentine modified product; the molar ratio of 2,3-epoxypine and 1,4-bis(3-aminopropyldimethylsilyl)benzene is 2:

1.

9. An asphalt mixture comprising polyphosphate-SBS polymer composite modified bio-asphalt and mineral aggregate as described in any one of claims 1-8.

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