High-viscosity modified asphalt and preparation method thereof

Abstract

The invention discloses high-viscosity modified asphalt and a preparation method thereof, and belongs to the technical field of asphalt materials, the high-viscosity modified asphalt comprises matrix asphalt, a tackifier, a styrene-butadiene-styrene block copolymer and a stabilizer, the mass ratio of the matrix asphalt to the tackifier to the styrene-butadiene-styrene block copolymer to the stabilizer is 100: (2-6): (2-6): (0.1-1); the tackifier comprises an epoxidized organic compound, a cross-linking agent and an accelerant, and the mass ratio of the epoxidized organic compound to the cross-linking agent to the accelerant is 100: (4-20): (0.5-3). According to the high-viscosity modified asphalt and the preparation method thereof disclosed by the invention, through composite construction of a thermally reversible network and a styrene-butadiene-styrene block copolymer (linear SBS) network, collaborative optimization among high-temperature performance, construction workability and low-temperature performance in a high-viscosity asphalt system is realized; the technical bottleneck that the three parts are difficult to consider in the traditional modification technology is broken through.

Description

Technical Field

[0001] This invention relates to the field of asphalt materials technology, and in particular to a high-viscosity modified asphalt and its preparation method. Background Technology

[0002] Permeable asphalt pavement, with its high porosity, has become an important pavement type in hot and rainy regions. Meanwhile, ultra-thin overlays have been widely used as an efficient preventative maintenance technique. However, their inherent structural defects result in poor rutting resistance and durability. To compensate for these shortcomings, high-performance, high-viscosity modified asphalt must be used as the key binder.

[0003] High-viscosity modified asphalt is crucial for improving the performance of asphalt mixtures, specifically in terms of: extremely high dynamic viscosity at 60℃ (typically requiring ≥20,000 Pa·s, with some requiring no less than 200,000 Pa·s) to provide strong inter-aggregate bonding and resist aggregate dispersion and high-temperature rutting; simultaneously, a suitable rotational viscosity at 135℃ is required to ensure good pumping and mixing performance during construction; furthermore, high-viscosity modified asphalt must also have excellent ductility at 5℃ to ensure the pavement's resistance to cracking under low-temperature conditions. Therefore, developing a high-viscosity modified asphalt that can simultaneously meet these three key performance indicators is an urgent common need in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a high-viscosity modified asphalt and its preparation method. By constructing a composite of a thermally reversible network and a styrene-butadiene-styrene block copolymer (linear SBS) network, the high-viscosity asphalt system achieves synergistic optimization of high-temperature performance, workability, and low-temperature performance, breaking through the technical bottleneck of traditional modification technologies where it is difficult to achieve all three aspects simultaneously.

[0005] To achieve the above objectives, the present invention provides a high-viscosity modified asphalt, comprising a base asphalt, a tackifier, a styrene-butadiene-styrene block copolymer, and a stabilizer, wherein the mass ratio of the base asphalt, the tackifier, the styrene-butadiene-styrene block copolymer, and the stabilizer is 100:2-6:2-6:0.1-1; Tackifiers include epoxidized organic compounds, crosslinking agents, and accelerators, with a mass ratio of 100:4-20:0.5-3.

[0006] Preferably, the epoxidized organic compound is at least one of epoxidized natural rubber, polypropylene grafted with glycidyl methacrylate, epoxy resin, and epoxidized soybean oil, more preferably epoxidized natural rubber; the crosslinking agent is at least one of 4-carboxyphenylboronic acid, 4-carboxyphenylboronic acid pinacol ester, and 3-carboxyphenylboronic acid pinacol ester, more preferably 4-carboxyphenylboronic acid pinacol ester; the accelerator is at least one of 1,2-dimethylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, and triethylamine, more preferably 1,2-dimethylimidazole.

[0007] Preferably, the stabilizer is at least one of sulfur, polyphosphate, diphenyl disulfide, and diphenyl sulfide, and more preferably sulfur.

[0008] Preferably, the base asphalt is 90# base asphalt.

[0009] This invention also provides a method for preparing high-viscosity modified asphalt, comprising the following steps: S1. Mix the epoxidized organic compound, crosslinking agent and accelerator, stir and react to obtain a thickener; S2. Heat the base asphalt, stir, add the styrene-butadiene-styrene block copolymer and the tackifier obtained in S1, raise the temperature, mix, add sulfur to react, and after the reaction is completed, shear swelling and development are obtained to obtain high viscosity modified asphalt.

[0010] Preferably, in S1, the stirring speed is 40-80 rpm, the stirring temperature is 60-100℃, and the stirring time is 10-30 min.

[0011] Preferably, in S1, the reaction temperature is 130-180℃ and the reaction time is 10-30 min.

[0012] Preferably, in S2, the base asphalt is heated to 140-160℃, the stirring speed is 480-500 rpm, the mixing temperature is 170-190℃, the mixing speed is 500-1000 rpm, and the mixing time is 30-50 min.

[0013] Preferably, in S2, the reaction time is 10-20 min.

[0014] Preferably, in S2, the shear swelling temperature is 190-210℃, the shear swelling rotation speed is 3000-5000 rpm, and the shear swelling time is 30-60 min.

[0015] Preferably, in S2, the development temperature is 160-190℃ and the development time is 30-60min.

[0016] The principle of this invention is as follows: On one hand, the carboxyl group of the crosslinking agent undergoes a ring-opening reaction with the epoxy group of the epoxy organic compound to generate a hydroxyl group; simultaneously, the BO bond at the other end of the crosslinking agent undergoes an ester exchange reaction with the hydroxyl group to construct a thermally reversible crosslinking network. For example... Figure 1 As shown, at high temperatures, the dissociation rate of dynamic borate ester bonds increases significantly, reducing the restriction of the thermally reversible network on asphalt and improving the fluidity of high-viscosity asphalt, thus facilitating construction. At low temperatures, the exchange reaction of borate ester bonds is in a kinetically stable state, maintaining the network structure and increasing the dynamic viscosity of high-viscosity asphalt. On the other hand, SBS is a styrene-butadiene-styrene block copolymer. At room temperature, the polystyrene microdomains are connected with flexible polybutadiene blocks to form a rubber support network, improving the viscosity of the base asphalt. However, when the temperature exceeds the glass transition temperature of polystyrene, these polystyrene domains dissociate, and the physical cross-linked network disappears, achieving an increase in dynamic viscosity at 60°C while maintaining a low rotational viscosity at 135°C.

[0017] Therefore, the present invention employs the above-mentioned high-viscosity modified asphalt and its preparation method, which has the following beneficial effects: (1) The high viscosity modified asphalt provided by the present invention has a dynamic viscosity of 1,000,000 Pa·s at 60℃ and a rotational viscosity of only 3.21 Pa·s at 135℃. At the same time, the ductility at 5℃ reaches 46 cm, which far exceeds the requirements of the standard "JTG / T 3350-03-2020". It achieves a synergistic improvement in high temperature performance, low temperature performance and workability.

[0018] (2) The high viscosity modified asphalt provided by the present invention has excellent resilience, and its elastic recovery at 25°C can reach 99.9%.

[0019] (3) The high viscosity modified asphalt provided by the present invention has self-healing potential. At the service temperature of the road surface, the dynamic bonds inside the material can be reorganized, which helps to heal micro-damage and extend the service life of the road surface.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 These are schematic diagrams of the thermally reversible network and SBS network of the high-viscosity modified asphalt prepared in Examples 1-5 of this invention; Figure 2 This is the infrared spectrum of epoxidized natural rubber (ENR) and pinacol 4-carboxyphenylboronic acid (CAPE) in this invention; Figure 3 These are infrared spectra of the thickener (without high-temperature reaction) prepared in Example 1 of this invention at different temperatures; Figure 4These are the infrared spectra of the high-viscosity modified asphalt prepared by Comparative Examples 1 and 2 of this invention. in, Figure 4 Image (a) shows the infrared spectra of the high-viscosity modified asphalt prepared in Comparative Example 1 and Comparative Example 2. Figure 4 Image (b) is a magnified view of a portion of the infrared spectrum. Figure 4 (c) in the text refers to two specific wavenumbers, 966 cm⁻¹. -1 and 699cm -1 The ratio of FTIR absorbance at each location, A1 / A2; Figure 5 This is a master curve showing the storage modulus and loss modulus of the tackifier (RC5) prepared in Example 1 of the present invention and the epoxidized natural rubber (ENR) in Comparative Example 5 as a function of angular frequency. Figure 6 These are multi-stress creep recovery diagrams of the high-viscosity modified asphalt prepared in Example 1, Comparative Examples 1-3, and Comparative Example 5 of this invention; in, Figure 6 In the figure, (a) shows the strain-time curves of different samples. Figure 6 (b) in the middle is Figure 6 Enlarged view of the red area in (a) of the image. Figure 6 In the figure, (c) represents the average recovery percentage of different samples, and (d) represents the average irrecoverable creep compliance of different samples. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] In this invention, 90# base bitumen was purchased from Qilu Petrochemical Co., Ltd., linear SBS (SBS1301(YH-791)) was purchased from Sinopec Baling Petrochemical Co., Ltd., epoxidized natural rubber (ENR) was purchased from Shandong Kepler Chemical Co., Ltd., 4-carboxyphenylboronic acid pinacol ester (CAPE) was purchased from Tianjin Xiens Opd Technology Co., Ltd., sulfur was purchased from Shandong Shangshun Chemical Co., Ltd., 1,2-dimethylimidazole (DMI) was purchased from Beijing Mairuida Technology Co., Ltd., and commercially available high-viscosity agent was purchased from Shenzhen Honglu New Materials Technology Co., Ltd. Other experimental materials and instruments were conventional experimental materials in the field and could be purchased through commercial channels.

[0025] Example 1 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 8g of tackifier, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0026] The tackifiers include epoxidized natural rubber (epoxidized organic compound), 4-carboxyphenylboronic acid pinacol ester (crosslinking agent) and 1,2-dimethylimidazole (accelerator), with a mass ratio of epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole of 1000:73:7.5.

[0027] The preparation method of the above-mentioned high-viscosity modified asphalt includes the following steps: S1. Epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole are added to a stirred tank and stirred for 15 min at 80℃ and 50 rpm. Then the mixture is reacted at 150℃ for 15 min to obtain a tackifier. S2. Place 90# base asphalt in a reactor and heat it to 150°C. Stir at 500 rpm and add tackifier and linear SBS. Raise the temperature to 180°C and mix at 850 rpm for 45 minutes. Then add sulfur and continue stirring for 15 minutes. After the reaction is complete, use a shear machine to shear and swell at 195°C and 5000 rpm for 60 minutes. Then develop at 180°C for 60 minutes to obtain high-viscosity modified asphalt.

[0028] Example 2 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 16g of tackifier, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0029] The tackifiers include epoxidized natural rubber (epoxidized organic compound), 4-carboxyphenylboronic acid pinacol ester (crosslinking agent) and 1,2-dimethylimidazole (accelerator), with a mass ratio of epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole of 1000:73:7.5.

[0030] The preparation method of the high-viscosity modified asphalt described in this embodiment is the same as that in Example 1.

[0031] Example 3 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 24g of tackifier, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0032] The tackifiers include epoxidized natural rubber (epoxidized organic compound), 4-carboxyphenylboronic acid pinacol ester (crosslinking agent) and 1,2-dimethylimidazole (accelerator), with a mass ratio of epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole of 1000:73:7.5.

[0033] The preparation method of the high-viscosity modified asphalt described in this embodiment is the same as that in Example 1.

[0034] Example 4 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 8g of tackifier, 8g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0035] The tackifiers include epoxidized natural rubber (epoxidized organic compound), 4-carboxyphenylboronic acid pinacol ester (crosslinking agent) and 1,2-dimethylimidazole (accelerator), with a mass ratio of epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole of 1000:73:7.5.

[0036] The preparation method of the high-viscosity modified asphalt described in this embodiment is the same as that in Example 1.

[0037] Example 5 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 8g of tackifier, 16g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0038] The tackifiers include epoxidized natural rubber (epoxidized organic compound), 4-carboxyphenylboronic acid pinacol ester (crosslinking agent) and 1,2-dimethylimidazole (accelerator), with a mass ratio of epoxidized natural rubber, 4-carboxyphenylboronic acid pinacol ester and 1,2-dimethylimidazole of 1000:73:7.5.

[0039] The preparation method of the high-viscosity modified asphalt described in this embodiment is the same as that in Example 1.

[0040] Comparative Example 1 A high-viscosity modified asphalt comprises 400g of 90# base asphalt and 24g of styrene-butadiene-styrene block copolymer (linear SBS).

[0041] The preparation method of the above-mentioned high-viscosity modified asphalt includes the following steps: 90# base asphalt was placed in a reactor and heated to 150°C. Linear SBS was added while stirring at 500 rpm. The temperature was raised to 180°C and mixed at 850 rpm for 45 minutes. Then, shearing and swelling were performed at 195°C and 5000 rpm for 60 minutes, followed by development at 180°C for 60 minutes to obtain high-viscosity modified asphalt.

[0042] Comparative Example 2 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0043] The preparation method of the above-mentioned high-viscosity modified asphalt includes the following steps: 90# base asphalt was placed in a reactor and heated to 150°C. Linear SBS was added while stirring at 500 rpm. The temperature was raised to 180°C and mixed at 850 rpm for 45 minutes. Then, sulfur was added and stirring was continued for 15 minutes. After the reaction was completed, shearing and swelling were performed at 195°C and 5000 rpm for 60 minutes. Then, it was developed at 180°C for 60 minutes to obtain high-viscosity modified asphalt.

[0044] Comparative Example 3 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 2g of sulfur (stabilizer).

[0045] The preparation method of the high-viscosity modified asphalt in this comparative example is the same as that in comparative example 2.

[0046] Comparative Example 4 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 32g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0047] The preparation method of the high-viscosity modified asphalt in this comparative example is the same as that in comparative example 2.

[0048] Comparative Example 5 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 8g of epoxidized natural rubber, 24g of styrene-butadiene-styrene block copolymer (linear SBS), and 1.2g of sulfur (stabilizer).

[0049] The preparation method of the above-mentioned high-viscosity modified asphalt includes the following steps: 90# base asphalt was placed in a reactor and heated to 150°C. Epoxidized natural rubber and linear SBS were added while stirring at 500 rpm. The temperature was raised to 180°C and mixed at 850 rpm for 45 minutes. Then, sulfur was added and stirring was continued for 15 minutes. After the reaction was completed, shearing and swelling were performed at 195°C and 5000 rpm for 60 minutes, followed by development at 180°C for 60 minutes to obtain high-viscosity modified asphalt.

[0050] Comparative Example 6 A high-viscosity modified asphalt comprises 400g of 90# base asphalt, 1.2g of sulfur (stabilizer), and 32g of commercially available high-viscosity agent.

[0051] The preparation method of the above-mentioned high-viscosity modified asphalt includes the following steps: 90# base asphalt was placed in a reactor and heated to 150°C. It was stirred at 500 rpm and a commercially available high-viscosity agent was added. The temperature was raised to 180°C and mixed at 850 rpm for 45 minutes. Then sulfur was added and the mixture was stirred for another 15 minutes. After the reaction was completed, the mixture was sheared and swollen at 195°C and 5000 rpm for 60 minutes. Finally, it was developed at 180°C for 60 minutes to obtain high-viscosity modified asphalt.

[0052] The chemical structures of epoxidized natural rubber (ENR) and pinacol 4-carboxyphenylboronic acid (CAPE), as well as the changes in the chemical structure of the tackifier prepared in Example 1 at different temperatures, were analyzed using Fourier transform infrared spectroscopy (FTIR). The ATR mode of the infrared spectrometer was used, and the spectral recording range was 500-4000 cm⁻¹. -1 The resolution is 4cm. -1 The result is as follows Figure 2 and Figure 3 As shown, where Figure 2 Infrared spectra of ENR and CAPE, Figure 3 The images show the infrared spectra of the thickener (without high-temperature reaction) prepared in Example 1 at different temperatures.

[0053] from Figure 2 As can be seen from the infrared spectrum of ENR, 881 cm⁻¹ -1 The peak at 1371 cm⁻¹ is a characteristic peak of ethylene oxide in the CAPE infrared spectrum. -1 and 1249cm -1 Corresponding to the asymmetric and symmetric vibrations of the BO bond, respectively, 1679 cm -1 The peak at this point is a characteristic peak for the carbonyl group.

[0054] from Figure 3As can be seen from this, hydroxyl groups (3579cm) -1 ) and carbonyl (1744cm) -1 The peak intensity of ) gradually increases with increasing temperature, and the peak intensity of epoxy group (881 cm⁻¹) increases. -1 The peak intensity of ) gradually decreased with increasing temperature. This confirms that a ring-opening reaction occurred between the carboxyl group of CAPE and the epoxy group of ENR, forming a β-hydroxy ester bond.

[0055] The high-viscosity modified asphalt prepared in Comparative Examples 1 and 2 was dissolved in CS2 solvent to prepare a 50 mg / mL solution. Two drops of the solution were added to a KBr crystal, and the mixture was heated under an electric furnace lamp to completely evaporate the CS2. The results were then analyzed using a Fourier transform infrared spectroscopy (FTIR) spectrometer with a wavenumber range of 500-4000 cm⁻¹. -1 4cm resolution -1 The result is as follows Figure 4 As shown, where Figure 4 (a) shows the infrared spectra of the high-viscosity modified asphalt prepared in Comparative Example 1 and Comparative Example 2; (b) shows a magnified view of a portion of the infrared spectrum; and (c) shows the spectra at two specific wavenumbers of 966 cm⁻¹. -1 and 699cm -1 The ratio of FTIR absorbance at point A1 / A2 (A1 is 966 cm⁻¹) -1 The absorbance at A2 is 699 cm⁻¹. -1 (Absorbance at the location).

[0056] from Figure 4 As can be seen from (a) in the figure, 2920cm -1 2850cm -1 The strong peak is caused by the aliphatic CH stretching vibration of the pitch fraction, at 1456 cm⁻¹. -1 1371cm -1 The peak at 1601 cm⁻¹ represents both the asymmetric and symmetric vibrational peaks of -CH₃. -1 and 750-900cm -1 The small peak at that point is caused by the C=C and CH vibrations of aromatic hydrocarbons in the asphalt.

[0057] from Figure 4 As can be seen from (b) in the figure, 966cm -1 699cm -1 The peaks at 966 cm⁻¹ represent the bending vibration of -CH=CH⁻ in the polybutadiene segment and the CH vibration of the benzene ring. After vulcanization, the C=C peak in the polybutadiene segment decreases, thus at two specific wavenumbers of 966 cm⁻¹. -1 and 699cm -1 The FTIR absorbance ratio A1 / A2 was calculated to provide a reference for the relative strength of the corresponding functional groups in high-viscosity modified asphalt. Figure 4As can be seen from (c), the ratio of absorbance of Comparative Example 2 to that of Comparative Example 1 is smaller, indicating that the addition of sulfur causes SBS to undergo sulfidation.

[0058] Dynamic frequency scanning tests were performed on the tackifier (RC5) prepared in Example 1 and the epoxidized natural rubber (ENR) in Comparative Example 5 at 60℃, 90℃, 135℃, and 160℃ using an Anton Paar rheometer. The gap value of the rheometer was set to 2 mm, the rheological fixture used was an 8 mm parallel plate, and the frequency range was 0.1-100 rad / s. Using the time-temperature superposition principle (TTS), the curves were superimposed with 60℃ as the reference temperature to obtain the master curve. The test results are as follows. Figure 5 As shown. From Figure 5 As can be seen, the storage modulus of the tackifier increases significantly at high frequencies, and the intersection of the storage modulus and loss modulus of the tackifier shifts towards higher frequencies compared to ENR at low frequencies. This is attributed to the thermally reversible network formed in the tackifier imparting a higher elastic modulus to the material at low temperatures, while the ENR molecular chains rely solely on physical entanglement and van der Waals forces, resulting in a lower storage modulus. At high temperatures, CAPE in the tackifier acts as a small-molecule plasticizer, causing the intersection of the storage modulus and loss modulus of the tackifier to shift towards higher frequencies. This also confirms the successful construction and dynamics of the thermally reversible network.

[0059] The high-viscosity modified asphalt samples prepared in Example 1, Comparative Examples 1-3, and Comparative Example 5 were subjected to multi-stress creep recovery tests at 0.1 kPa and 3.2 kPa using an Anton Par rheometer at 60 °C. The gap value of the rheometer was set to 1 mm, and a 25 mm parallel plate was used as the rheological fixture. Creep recovery curves of different samples were obtained, and the average percentage recovery (R) and average non-recoverable creep compliance (J) were introduced. nr The test results are as follows: Figure 6 As shown, where Figure 6 In the figure, (a) is the strain-time curve of different samples, (b) is a magnified view of the red area in (a), (c) is the average recovery percentage of different samples, and (d) is the average unrecoverable creep compliance of different samples.

[0060] from Figure 6 As can be seen from (a), (b), (c), and (d) in the figure, at 0.1 kPa, with the increase of sulfur content, the R value and J value of high-viscosity modified asphalt increase. nr The smaller the value, the better the high-temperature performance (the larger the average recovery percentage R, the better the recovery ability of the asphalt; the average unrecoverable creep compliance J). nrThe smaller the value, the better the asphalt's resistance to rutting. At 3.2 kPa, the R-value of Comparative Example 3 is smaller than that of Comparative Example 2. This may be because the SBS network in Comparative Example 3 has certain thermosetting properties, resulting in poor recovery under high stress. Compared to Comparative Examples 1-3 and Comparative Example 5, Example 1 has the largest R-value. nr The smallest value indicates that it has the best high-temperature resistance to rutting.

[0061] According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the dynamic viscosity at 60℃, rotational viscosity at 135℃, ductility at 5℃, penetration at 25℃, elastic recovery at 25℃, and softening point of the high-viscosity modified asphalt samples prepared in Examples 1-5 and Comparative Examples 1-6 were tested. The test results are shown in Table 1.

[0062] Table 1. Comparison of six basic properties of different high-viscosity modified asphalts

[0063] As shown in Table 1, Comparative Example 1, which only uses SBS for conventional asphalt modification, exhibits insufficient dynamic viscosity at 60℃ and ductility at 5℃, with only the rotational viscosity at 135℃ (<3 Pa·s) meeting the requirements for workability. With increasing sulfur content, the crosslinking density of the system increases, and both the dynamic viscosity at 60℃ and the rotational viscosity at 135℃ rise significantly, a trend consistent with that of traditional high-viscosity asphalt. This result indicates that although enhanced chemical crosslinking can effectively improve high-temperature performance, it inevitably leads to increased workability and deteriorated low-temperature toughness, specifically manifested in a significant decrease in ductility at 5℃. In contrast, the comparative analysis of Example 1 and Comparative Example 5 clearly reveals the synergistic enhancement effect resulting from the introduction of a thermally reversible network. Under the action of the thermally reversible network, the dynamic viscosity of the high-viscosity modified asphalt at 60℃ significantly increased from 330.4 kPa·s to 454.6 kPa·s, an increase of 37.6%; at the same time, the rotational viscosity at 135℃ did not increase, but instead decreased to 3.21 Pa·s, effectively ensuring the mixing and pumping performance during construction; more importantly, the low-temperature crack resistance of the material was significantly improved, with the ductility at 5℃ increasing from 26.2 cm to 46.4 cm, an increase of up to 77%.

[0064] Therefore, the present invention adopts the above-mentioned high-viscosity modified asphalt and its preparation method, and through the composite construction of thermally reversible network and SBS network, achieves synergistic optimization of high-temperature performance, workability and low-temperature performance in high-viscosity asphalt system, and breaks through the technical bottleneck of traditional modification technology that makes it difficult to balance the three aspects.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-viscosity modified asphalt, characterized in that: It includes base asphalt, tackifier, styrene-butadiene-styrene block copolymer and stabilizer, with the mass ratio of base asphalt, tackifier, styrene-butadiene-styrene block copolymer and stabilizer being 100:2-6:2-6:0.1-1; Tackifiers include epoxidized organic compounds, crosslinking agents, and accelerators, with a mass ratio of 100:4-20:0.5-3.

2. The high-viscosity modified asphalt according to claim 1, characterized in that: The epoxidized organic compound is at least one of epoxidized natural rubber, polypropylene grafted with glycidyl methacrylate, epoxy resin, and epoxidized soybean oil; the crosslinking agent is at least one of 4-carboxyphenylboronic acid, 4-carboxyphenylboronic acid pinacol ester, and 3-carboxyphenylboronic acid pinacol ester; and the accelerator is at least one of 1,2-dimethylimidazole, 2,4,6-tris(dimethylaminomethyl)phenol, and triethylamine.

3. The high-viscosity modified asphalt according to claim 1, characterized in that: The stabilizer is at least one of sulfur, polyphosphate, diphenyl disulfide, and diphenyl sulfide.

4. A method for preparing a high-viscosity modified asphalt as described in any one of claims 1-3, characterized in that: Includes the following steps: S1. Mix the epoxidized organic compound, crosslinking agent and accelerator, stir and react to obtain a thickener; S2. Heat the base asphalt, stir, add the styrene-butadiene-styrene block copolymer and the tackifier obtained in S1, raise the temperature, mix, add sulfur to react, and after the reaction is completed, shear swelling and development are obtained to obtain high viscosity modified asphalt.

5. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S1, the stirring speed is 40-80 rpm, the stirring temperature is 60-100℃, and the stirring time is 10-30 min.

6. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S1, the reaction temperature is 130-180℃ and the reaction time is 10-30 min.

7. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S2, the base asphalt is heated to 140-160℃, the stirring speed is 480-500 rpm, the mixing temperature is 170-190℃, the mixing speed is 500-1000 rpm, and the mixing time is 30-50 min.

8. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S2, the reaction time is 10-20 minutes.

9. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S2, the temperature for shear swelling is 190-210℃, the rotation speed for shear swelling is 3000-5000 rpm, and the time for shear swelling is 30-60 min.

10. The method for preparing high-viscosity modified asphalt according to claim 4, characterized in that: In S2, the development temperature is 160-190℃ and the development time is 30-60 minutes.

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