Graphene / sbs composite modified asphalt and preparation method thereof

Abstract

The application discloses graphene and SBS composite modified asphalt and a preparation method thereof, and relates to the technical field of asphalt modification materials, and comprises the following components: base asphalt, SBS and surface-activated graphene; the surface-activated graphene is added into the SBS modified asphalt; the rich oxygen-containing functional groups on the surface of the graphene can effectively improve the dispersibility and compatibility of the graphene in the asphalt, and the agglomeration phenomenon is avoided; in addition, the rigid skeleton structure formed by the high tensile strength of the graphene can effectively inhibit the movement and plastic flow of asphalt molecules under the action of heat; the SBS can relieve stress concentration through excellent elastic recovery characteristics; and the synergistic effect of the two can significantly improve the anti-aging performance and storage stability of the asphalt; the preparation method and process control are difficult to control, the production cost is low, and the method has high engineering economy and process feasibility.

Description

Technical Field

[0001] This invention relates to the field of asphalt modification materials technology, and in particular to a graphene / SBS composite modified asphalt and its preparation method. Background Technology

[0002] As a core component of modern transportation infrastructure, asphalt pavement's engineering quality has a significant impact on national economic development. Traditional asphalt materials gradually exhibit obvious performance defects and are prone to aging, especially under extreme climatic conditions. Specifically, traditional asphalt pavements are susceptible to rutting and deformation in high-temperature seasons, and fatigue cracking in low-temperature environments, severely affecting pavement performance and service life.

[0003] To address the technical limitations of traditional asphalt materials, modified asphalt technology has emerged and developed rapidly. Polymer-modified asphalt, with its excellent comprehensive performance, is widely used in high-grade asphalt pavements. One typical example is SBS (styrene-butadiene-styrene block copolymer) modified asphalt, which has good high-temperature stability, low-temperature crack resistance, and water stability. However, under long-term exposure to complex environmental conditions, SBS modified asphalt still faces severe aging problems. Under the influence of multiple factors such as oxygen, ultraviolet radiation, temperature cycling, and moisture erosion, the polymer molecular chains are prone to breakage and degradation, leading to the deterioration of the modified asphalt's performance and thus affecting the long-term service performance of the pavement.

[0004] Among the existing proposed improvement technologies, some utilize nano-reinforcement effects and interfacial bonding to improve the anti-aging properties of SBS modified asphalt. For example, patent CN 115093713 A proposes a graphene-modified asphalt and its preparation method. The raw materials for preparing the modifier include graphene, SBS, polyurethane, rubber, compatibilizer, coupling agent, sulfur, and accelerator. Although the modified asphalt described in this patent has good anti-aging properties, the preparation method described therein has high production costs and is difficult to control. In addition, although the sulfur vulcanization system can improve elasticity, it is prone to causing a decrease in storage stability (high-temperature segregation) and performance degradation after long-term aging (sulfurization).

[0005] Therefore, this invention proposes a graphene / SBS composite modified asphalt and its preparation method, which combines anti-aging properties, storage stability, engineering economy, and process feasibility. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a graphene / SBS composite modified asphalt and its preparation method, so that the modified asphalt has anti-aging properties, storage stability, engineering economy and process feasibility.

[0007] To address the problems of the prior art, the technical solution of the present invention is as follows: A method for preparing graphene / SBS composite modified bitumen includes the following steps: S1. Surface activation treatment of graphene: Graphene is surface treated with an alcohol-water solution prepared with silane coupling agent KH-550, and then dried and ground to obtain graphene powder surface activated with silane coupling agent KH-550. Surface-activated graphene was prepared using a drying and concentration method to improve its dispersibility and interfacial bonding in asphalt systems. Although the dosage of the silane coupling agent KH-550 used to activate the graphene was relatively small, efficient chemical bonding on the graphene surface was achieved through an alcohol-water-mediated drying process, ensuring the activation effect.

[0008] The specific steps are as follows: First, add the weighed silane coupling agent KH-550 to a beaker containing an alcohol-water solution (anhydrous ethanol and distilled water are added at an alcohol-water ratio of 10:1), stir it evenly with a glass rod, and preheat it to 50-60℃ using an adjustable temperature heater; then, add graphene to the preheated ethanol beaker in proportion, and stir until uniform by controlling the stirring speed and heating temperature with a stirrer; finally, after the solution is mixed evenly, put it in an oven to dry. After the alcohol-water solution has completely evaporated, grind the obtained solid into powder, which is the surface-activated graphene material.

[0009] S2. Preparation of graphene / SBS composite modified asphalt: The graphene powder and SBS modifier were mixed into the base asphalt by high-speed shearing and uniformly sheared to obtain graphene / SBS composite modified asphalt. (1) Asphalt dehydration pretreatment: Weigh an appropriate amount of base asphalt and heat it to a molten and fluid state. Place the container of molten asphalt on an electric furnace lined with asbestos mesh and stir it continuously with a glass rod during the heating process to evaporate the residual water in the asphalt; (2) SBS shear dispersion: Place the container containing the pretreated asphalt and the electric furnace together under the high-speed shear machine and start the shear machine. First, add the SBS modifier. Initially, set the rotation speed to 1500 r / min. Under this low-speed condition, slowly add the SBS particles and perform preliminary shear dispersion. (3) High-speed shearing and graphene addition: After the SBS particles are uniformly sheared, the rotation speed is gradually increased to 4000-7000 r / min. Under this condition, after high-speed shearing for 40 min, graphene powder that has been surface activated by silane coupling agent KH-550 in step 1 is added, and shearing continues for 30 min. During shearing, the asphalt temperature is controlled at 155℃~165℃.

[0010] S3. Proportioning optimization and performance verification steps: The optimal combination dosage of SBS and graphene was determined through two-component full factorial experimental design to obtain the graphene / SBS composite modified asphalt with the best performance.

[0011] (1) The optimal combination of SBS and graphene dosage was determined through a two-component full factorial experiment: Through systematic formulation optimization experiments, the optimal blending ratio of graphene and SBS modifier in base asphalt was determined. During the optimization process, SBS modifier dosage levels of 3.5%, 4%, 4.5%, 5%, and 5.5% (based on the mass percentage of 100g base asphalt) were selected, while graphene dosage levels of 0%, 0.05%, 0.1%, 0.15%, and 0.2% were selected. Twenty-five graphene / SBS composite modified asphalt samples were prepared using a two-component full-factor experimental design. The optimal blending ratio was selected by comprehensively evaluating the basic performance indicators (penetration, softening point, ductility) and anti-aging properties of each sample.

[0012] (2) Using multi-source performance evaluation indicators, the excellent performance of graphene / SBS composite modified asphalt was verified: Multiple analytical methods, including rotating thin-film oven aging test (RTFOT), dynamic shear rheology test (DSR), flexural beam rheology test (BBR), and segregation test, were used to evaluate the performance of modified asphalt in terms of anti-aging ability, rheological properties, and storage stability. Comparative analysis of the test results of different groups of modified asphalt further verified the comprehensive superiority of graphene / SBS composite modified asphalt in multiple performance indicators, revealing its significant potential in anti-aging performance, storage stability, economy, and process feasibility.

[0013] (3) Based on microstructure characterization and chemical analysis experiments, the modification mechanism of graphene / SBS composite modified asphalt was revealed: The microstructure and chemical evolution of composite modified asphalt were investigated using a combination of microstructural characterization and chemical analysis techniques. First, scanning electron microscopy (SEM) was used to observe the microstructure of composite modified asphalt with optimized ratios of 14# (4.5% SBS + 0.15% graphene) and 7# (4% SBS + 0.05% graphene). This visually revealed the dispersion state of SBS and activated graphene in the asphalt matrix and the multiphase interface structure they formed, providing direct evidence for understanding physical blending and interfacial interactions. Second, Fourier transform infrared spectroscopy (FTIR) was used to quantitatively track the evolution of characteristic functional groups during aging, focusing on monitoring the trends of the carbonyl index (CI, absorption peak at 1710 cm⁻¹) and the sulfoxide index (SI, absorption peak at 1030 cm⁻¹). Based on the combined results of microstructure and chemical analysis, activated graphene, with its unique two-dimensional sheet structure, effectively blocks the intrusion of aging media such as oxygen and moisture, slowing down the oxidation reaction rate. The large π-bond conjugated system of graphene can capture free radicals generated during the thermo-oxidative aging process of asphalt, interrupting the chain oxidation reaction. The physical cross-linking network formed by SBS polymers not only improves the toughness and crack resistance of asphalt but also restricts the thermal motion of asphalt molecules through physical cross-linking, reducing its oxidative activity. The synergistic effect of these three mechanisms results in composite modified asphalt exhibiting superior anti-aging properties at both the microstructure and chemical composition levels.

[0014] Compared with the prior art, the advantages of the present invention are as follows: 1. This invention increases the compatibility between graphene and SBS modifier by surface-activated graphene, promoting the interfacial bonding between graphene and SBS. The two-dimensional graphene sheets can form a physical barrier to prevent the intrusion of aging media such as oxygen and moisture. Its large π-bond conjugated system can capture free radicals generated during aging, interrupt the chain oxidation reaction, and inhibit the formation of oxidation products such as carbonyl and sulfoxide groups. At the same time, the rigid framework of graphene can restrict the thermal motion and plastic flow of asphalt molecules, and the elastic network of SBS disperses stress and reduces the oxidation activity of asphalt. The two interpenetrate to form a stable composite cross-linked system, effectively maintaining the integrity of the material, inhibiting molecular chain degradation, and significantly delaying the oxidative aging process of asphalt.

[0015] 2. The layered structure of the activated graphene in this invention can play a physical barrier role, and its surface polarity can enhance the adsorption capacity of SBS. Combined with the three-dimensional network formed by itself, it can effectively delay the aggregation of SBS and restrict its free migration, thereby significantly inhibiting the phase separation process of the system and improving storage stability.

[0016] 3. In this invention, graphene sheets fill the voids in the SBS network to form a synergistic reinforcement structure, which improves the thermal stability and high-temperature rheological properties of the system, enhances the high-temperature rutting resistance of asphalt, and under appropriate dosage, graphene will not excessively increase the hardness of asphalt. Asphalt can maintain both rigidity and good fluidity. Although graphene will slightly reduce the low-temperature flexibility of asphalt, all composite modified asphalts meet the standard low-temperature performance indicators. The toughening effect of SBS is dominant, so that the material still has good low-temperature ductility and crack resistance.

[0017] 4. This invention utilizes the silane coupling agent KH-550 to activate the surface of graphene. The activation process leverages the volatility of the alcohol-water solution and uses ethanol to ensure uniform dispersion of the coupling agent in the system, allowing graphene and the coupling agent to fully contact. After hydrolysis, the coupling agent can form covalent bonds with the hydroxyl groups on the graphene surface, constructing an "inorganic-organic" interface bridge with the help of amino groups and grafting oxygen-containing functional groups. This effectively inhibits the aggregation of graphene itself and significantly improves the dispersion state of graphene in the asphalt matrix, strengthening the interfacial bonding of graphene, SBS, and asphalt, and fully leveraging the modification potential of graphene.

[0018] 5. This invention uses an alcohol-water solution prepared with an organosilane coupling agent as an activator to prepare surface-activated graphene by drying. The obtained surface-activated graphene composite SBS is then used to modify asphalt by high-speed shearing. The preparation method and process control are simple, the production cost is low, and it has high engineering economics and process feasibility. Attached Figure Description

[0019] Figure 1 This is a technical roadmap for the preparation of graphene and SBS composite modified asphalt according to the present invention.

[0020] Figure 2 This is a flowchart of the graphene surface activation process of the present invention.

[0021] Figure 3 This is a flowchart illustrating the preparation process of the composite modified asphalt according to the present invention.

[0022] Figure 4 This is a graph showing the relationship between the rutting factor of the modified asphalt of this invention and temperature.

[0023] Figure 5 This is a SEM image of the matrix bitumen of this invention.

[0024] Figure 6 This is a SEM image of the 4.5% SBS modified bitumen of this invention.

[0025] Figure 7 This is a SEM image of the 0.15% graphene-modified asphalt of this invention.

[0026] Figure 8 This is a SEM image of the No. 7 composite modified asphalt of this invention.

[0027] Figure 9 This is a SEM image of the No. 14 composite modified asphalt of this invention.

[0028] Figure 10 This is the infrared spectrum of asphalt before aging according to the present invention.

[0029] Figure 11 This is the infrared spectrum of the aged asphalt of this invention. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] A method for preparing graphene / SBS composite modified bitumen includes the following steps: S1. Surface activation treatment of graphene: Graphene is surface treated with an alcohol-water solution prepared with silane coupling agent KH-550, and then dried and ground to obtain graphene powder surface activated with silane coupling agent KH-550. S2. Preparation of graphene / SBS composite modified asphalt: The graphene powder and SBS modifier were mixed into the base asphalt by high-speed shearing and uniformly sheared to obtain graphene / SBS composite modified asphalt. S3. Proportioning optimization and performance verification steps: The optimal combination dosage of SBS and graphene was determined through two-component full factorial experimental design to obtain the graphene / SBS composite modified asphalt with the best performance.

[0032] Reference Figure 1-3 The following details the preparation technology and performance analysis of graphene and SBS composite modified asphalt: 1. Graphene is surface-treated using an alcohol-water solution prepared with an organosilane coupling agent as an activator. First, due to the good hydrophilicity of graphene, its compatibility with the good hydrophobic SBS material is relatively poor. However, after activation treatment, oxygen-containing functional groups are grafted onto the surface of graphene, which can effectively improve its dispersion in the asphalt matrix and its interfacial compatibility with SBS, laying the foundation for fully leveraging the modification advantages of graphene in the future.

[0033] Secondly, adding a trace amount of silane coupling agent to graphene plays a very important role, but there is a certain prerequisite, which is to ensure that the coupling agent is uniformly dispersed in the system. Ethanol has the advantage of fast evaporation and no adverse effects, which allows graphene and coupling agent to come into full contact. Therefore, the direct processing method of drying is used to prepare surface-activated graphene.

[0034] This invention employs silane coupling agent KH-550 to activate the surface of graphene. The silane coupling agent KH-550 molecule contains an inorganic-loving group (triethoxysilane) and an organic-loving group (amino group): in an alcohol-water system, triethoxysilane hydrolyzes to generate silanol (-Si-OH), which undergoes a condensation reaction with the hydroxyl groups (-OH) on the graphene surface to form covalent bonds; while the amino group endows the graphene surface with organic active sites, realizing "inorganic-organic" interface bridging, while inhibiting graphene aggregation.

[0035] Surface-activated graphene can increase the compatibility between graphene and SBS modifier, promote the interfacial bonding between graphene and SBS, and directly strengthen the interaction of the graphene-SBS-asphalt three-phase interface.

[0036] The graphene described in this invention is a single-layer graphene, which is in the form of a black powder, and its basic properties are shown in Table 1.

[0037] Table 1 Basic Performance Indicators of Graphene

[0038] The silane coupling agent KH-550 described in this invention uses γ-aminopropyltriethoxysilane, with the molecular formula [missing information]. It is a colorless, transparent to light yellow liquid with a characteristic ammonia odor. Its basic properties are shown in Table 2.

[0039] Table 2 Basic Performance Indicators of Silane Coupling Agents

[0040] The specific steps for graphene surface activation are as follows: Figure 2 As shown: First, weigh 0.8% of the graphene mass of silane coupling agent KH-550 and add it to a beaker containing an appropriate amount of alcohol-water solution. Stir it with a glass rod until it is completely dissolved to obtain a uniform coupling agent ethanol solution. Then, place the beaker on a temperature-adjustable heater and preheat it to 50-60℃; subsequently, slowly add the weighed graphene powder to the preheated ethanol solution, while turning on the stirrer and controlling the stirring speed to 500-1000 r / min, and continue stirring under constant temperature for 30-40 min to allow the graphene and coupling agent to react fully. After mixing thoroughly, the resulting suspension was transferred to an oven and dried at 80°C for 12 hours to allow the ethanol to evaporate completely. Finally, the dried solid product is ground into fine powder to obtain graphene powder that has been surface activated by silane coupling agent KH-550.

[0041] 2. Achieving uniform dispersion of graphene / SBS composite modified asphalt based on a high-speed shearing method. This invention employs a high-speed shearing method to prepare graphene / SBS composite modified asphalt. By optimizing the shearing process parameters, the uniformity of the modifier in the asphalt system is achieved. The specific preparation steps are as follows: (1) Asphalt dehydration pretreatment: Weigh an appropriate amount of base asphalt, heat it to a molten and fluid state, place the container of molten asphalt on an electric furnace covered with asbestos mesh, and stir it continuously with a glass rod during the heating process to evaporate the residual water in the asphalt. (2) SBS shear dispersion: Place the container containing the pretreated asphalt and the electric furnace together under the high-speed shear machine, start the shear machine, add the SBS modifier first, initially set the speed to 1500 r / min, under this low speed condition, slowly add the SBS particles and initially shear disperse them. (3) High-speed shearing and graphene addition: After the SBS particles are uniformly sheared, the rotation speed is gradually increased to 4000-7000 r / min. Under this condition, after high-speed shearing for 40 min, graphene powder that has been surface activated by silane coupling agent KH-550 in step 1 is added, and shearing continues for 30 min. During shearing, the asphalt temperature is controlled at 155℃~165℃.

[0042] 3. The optimal combination of SBS and graphene dosage was determined through two-component full factorial experiments. The base asphalt used in this invention is No. 70 road petroleum asphalt. The basic properties of the base asphalt were tested in accordance with the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025). The performance indicators are shown in Table 3.

[0043] Table 3 Main Technical Indicators of Base Asphalt

[0044] The SBS modifier described in this invention is an SBS modifier manufactured by Kraton in the United States, and its basic properties are shown in Table 4.

[0045] Table 4 SBS Basic Performance Indicators

[0046] To systematically analyze the influence of the ratio of graphene to SBS modifier on the performance of modified asphalt, this invention selected SBS modifier dosages of 3.5%, 4%, 4.5%, 5%, and 5.5%, and graphene dosages of 0%, 0.05%, 0.1%, 0.15%, and 0.2%, where the modifier dosages are all percentages of the base asphalt mass. Through a full factorial experimental design, a total of 25 groups of graphene / SBS composite modified asphalts with different ratios were prepared. The specific combination numbers and corresponding dosages are shown in Table 5.

[0047] Table 5 Composite Modified Asphalt Combination Design Table

[0048] Among them, five groups of samples (1#, 6#, 11#, 16#, and 21#) with 0% graphene content were used to determine the optimal content of SBS modifier in SBS modified asphalt, providing a reference for subsequent analysis of the effect of graphene on the anti-aging performance of SBS modified asphalt.

[0049] This invention first conducts preliminary tests and comparisons on 25 groups of samples based on basic performance tests such as penetration, softening point, and ductility, and preliminarily screens out the doping combinations with better performance, laying the foundation for further in-depth research on anti-aging properties, rheological properties, and storage stability.

[0050] The main experimental equipment and instruments used in the research of this invention and their models are shown in Table 6.

[0051] Table 6 Instrument Model List

[0052] This invention provides a comprehensive analysis of 25 comparative examples, aiming to lay the foundation for step 4 of the study on the influence of different dosages of modifiers and their combined effects on asphalt properties.

[0053] Based on the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), this invention conducts basic performance index tests on the above modified asphalt. The three major indicators of the composite modified asphalt are obtained through the test. The results of the penetration, softening point and ductility at 5℃ of graphene / SBS composite modified asphalt at various dosages are shown in Table 7.

[0054] Table 7. Test results of basic indicators for 25 sets of comparison pairs.

[0055] This invention compares the penetration, softening point, and ductility of 25 groups of graphene / SBS composite modified asphalt with different ratios, analyzes the influence of graphene and SBS content on asphalt performance, and selects the optimal ratio combination with better overall performance for further analysis.

[0056] (1) Penetration analysis The penetration of asphalt is an important indicator for measuring its fluidity and flexibility. A higher penetration indicates that the asphalt is softer and easier to flow. Analysis of the data in Table 7 shows that within the SBS content range of 3.5% to 5.5%, the penetration of each group of samples decreased as the graphene content increased from 0% to 0.1%, indicating that the addition of an appropriate amount of graphene enhanced the consistency and toughness of the asphalt. When the graphene content exceeded 0.15%, the downward trend of penetration slowed down. Under the same SBS content, the penetration continued to decrease with the increase of graphene content. The penetration of the high SBS content (5%, 5.5%) samples was generally higher than that of the low content group, but the addition of graphene still reduced the penetration.

[0057] Among them, combinations such as 14# (4.5% SBS + 0.15% graphene) and 20# (5% SBS + 0.2% graphene) maintained a high SBS content while the penetration was at a moderate level, indicating that the introduction of graphene did not excessively weaken the flexibility of asphalt, and the two can form a synergistic effect within the appropriate content range.

[0058] This phenomenon indicates that the elastic network of SBS improves the flexibility of asphalt, while the introduction of an appropriate amount of graphene does not excessively increase the hardness of asphalt. The two can form a synergistic effect within a suitable dosage range, enabling asphalt to maintain good fluidity while retaining a certain rigidity.

[0059] (2) Softening point analysis The softening point is an important indicator for measuring the high-temperature performance of asphalt, reflecting the asphalt's resistance to deformation at high temperatures. Test results show that the addition of graphene generally increases the softening point of SBS modified asphalt. The data analysis in Table 7 shows that the softening point is most significantly improved with a SBS doping content of 4.5%. Under the same SBS doping content, the softening point first increases and then decreases with the increase of graphene doping content: in the 4.5% SBS system, when the graphene doping content increases from 0% to 0.1%, the softening point increases from 62.7℃ (11#) to 64.8℃ (13#); but when the graphene doping content increases to 0.2% (15#), the softening point decreases to 63.9℃.

[0060] This indicates that an appropriate amount of graphene can form a synergistic reinforcing structure with the SBS network—graphene sheets fill the gaps in the SBS network, and the two are tightly bonded together, enhancing the thermal stability of the system; however, excessive graphene may lead to an overly dense network structure, which in turn affects the fluidity and processing performance of asphalt.

[0061] (3) Duration analysis Ductility is an indicator that measures the tensile deformation capacity of asphalt under external force. As can be seen from the data analysis in Table 7, under the same SBS content, the ductility generally decreases with the increase of graphene content.

[0062] Taking the 4.5% SBS system as an example, the lattice is 31.9 cm (11#) when the graphene doping is 0%, it decreases to 30.4 cm (12#) when it is 0.05%, it decreases to 29.8 cm (13#) when it is 0.1%, it further decreases to 29.7 cm (14#) when it is 0.15%, and it decreases to 28.1 cm (15#) when it is 0.2%.

[0063] This indicates that the graphene sheet structure physically hinders the flow of asphalt molecules, thus reducing the ductility. Conversely, the increase in SBS content significantly improves the ductility value: when the graphene content is 0%, the ductility increases from 30.5% to 5.5% when the SBS content increases from 3.5% to 33.6cm (1#) to 33.6cm (21#).

[0064] The two have opposite effects on ductility. In the composite system, the toughening effect of SBS is dominant, which enables the composite modified asphalt to maintain good low-temperature ductility.

[0065] This invention comprehensively considers multiple factors such as penetration, softening point, and ductility of the composite modified asphalt and conducts a comparative analysis of 25 comparative samples. Among them, sample 14# showed the best overall performance, with its softening point, penetration, and ductility achieving the best balance, and subsequent anti-aging tests showed that its performance was optimal. Sample 7# showed a more balanced performance and cost advantage. Therefore, further in-depth verification and analysis will be conducted on samples 14# and 7# through a multi-source evaluation system including anti-aging performance, rheological properties, and storage stability.

[0066] 4. Using multi-source performance evaluation indicators, the excellent performance of graphene / SBS composite modified asphalt was verified. To systematically evaluate the comprehensive road performance of graphene / SBS composite modified asphalt, this invention constructs a complete performance evaluation system from multiple dimensions, including macroscopic performance, rheological properties, and storage stability. Through systematic pre- and post-aging performance comparison tests on the following implementation examples 1-5 (base asphalt, 4.5% SBS modified asphalt, 0.15% graphene modified asphalt, 7# composite modified asphalt, and 14# composite modified asphalt), the influence of different modification systems on the anti-aging performance, high and low temperature performance, and storage stability of asphalt is comprehensively analyzed.

[0067] Example 1: Base asphalt, whose performance meets the technical requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG 3410-2025).

[0068] Example 2: Preparation process of 4.5% SBS modified asphalt Step 1: First, heat the base asphalt to a molten and fluid state. Then, for every 100g of base asphalt, slowly add 4.5% SBS modifier to the asphalt while manually stirring with a glass rod until the modifier is completely submerged in the asphalt. Step 2: Place the container of asphalt impregnated with the modifier under a high-speed shearing machine. An electric furnace is placed below to maintain the temperature. Start the shearing machine and shear at a low speed (about 1000 r / min) first, then slowly adjust to 4500 r / min and shear at high speed for 30 minutes. During the shearing, keep the asphalt temperature between 155℃ and 165℃ to ensure that the asphalt is in a fluid state with low consistency, while avoiding aging of the asphalt due to excessive temperature.

[0069] Example 3: Preparation process of 0.15% graphene-modified asphalt The only difference from Example 2 is that the type and amount of modifier added are adjusted to 0.15% (based on the mass percentage of 100g of base asphalt) of graphene powder after surface treatment with silane coupling agent KH-550. Other operating steps and conditions are the same as in Example 2.

[0070] Example 4: Preparation process of No. 7 composite modified asphalt Step 1: Weigh an appropriate amount of base asphalt and heat it to a molten and flowing state. Place the container of molten asphalt on an electric furnace lined with asbestos mesh. The purpose of using asbestos mesh is to prevent the asphalt from aging prematurely due to excessive local temperature. Stir constantly with a glass rod during the heating process to allow the residual moisture in the asphalt to evaporate. Step 2: Place the container containing asphalt and the electric furnace together under the shearing machine. First, add SBS modifier (4% dosage). Initially, set the rotation speed to 1500 r / min to slowly shear and disperse the SBS particles evenly. After the SBS is initially dispersed, gradually adjust the rotation speed to 4000-7000 r / min and shear at high speed for 40 minutes to allow the SBS to fully swell and form a uniform network. Step 3: Add graphene powder (0.05% dosage) that has been surface activated by silane coupling agent KH-550, and continue shearing for 30 minutes to ensure that the graphene is uniformly dispersed in the asphalt system. The temperature is controlled at 155~165℃ throughout the shearing process.

[0071] Example 5: Preparation process of #14 composite modified asphalt The only difference from Example 4 is that the amount of SBS modifier added is adjusted to 4.5%, the amount of surface-activated graphene added is adjusted to 0.15%, and other conditions are the same as in Example 4.

[0072] It should be noted that in all preparation processes, the base asphalt was No. 70 road petroleum asphalt, whose performance met the requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG 3410-2025); the SBS modifier was styrene-butadiene-styrene block copolymer; the graphene was all powder activated by the method described in step 1; and the shear temperature in Examples 2 to 5 was strictly controlled at 155 to 165℃ to ensure the modification effect and avoid thermal aging.

[0073] The following is a comparative analysis of the system performance before and after aging for implementation examples 1-5: (1) Evaluation of resistance to thermo-oxidative aging This invention uses the Rotating Thin Film Oven Test (RTFOT) to simulate the short-term thermo-oxidative aging process of asphalt. The anti-aging performance of different modified asphalts is evaluated by key indicators such as mass loss, residual penetration ratio, ductility retention and softening point increment. The results are shown in Tables 8-11.

[0074] Table 8. Asphalt quality loss after aging

[0075] The mass loss rate is a key indicator for evaluating the anti-aging performance of asphalt. The more significant the mass loss, the more serious the loss of lightweight components in the material, and the weaker its antioxidant capacity. The test results in Table 8 show that the mass loss of all modified asphalts after aging was lower than that of the base asphalt. The mass loss of 7# composite modified asphalt (0.13%) was 64.9% lower than that of 4.5% SBS modified asphalt (0.37%), and the mass loss of 14# composite modified asphalt was 83.8% lower, indicating that the addition of graphene significantly improved the anti-aging performance of SBS modified asphalt. The order of mass loss was: 14# composite modified asphalt < 7# composite modified asphalt < 4.5% SBS modified asphalt < 0.15% graphene modified asphalt < base asphalt.

[0076] Table 9 Comparison of Asphalt Penetration Before and After Aging

[0077] The residual penetration ratio directly reflects the changes in the hardness and performance retention of asphalt before and after aging. As shown in Table 9, the residual penetration ratio of all modified asphalts was significantly higher than that of base asphalt, indicating that the addition of modifiers improved the anti-aging performance. However, the residual penetration ratio was ranked as follows: 14# composite modified asphalt > 7# composite modified asphalt > 4.5% SBS modified asphalt > 0.15% graphene modified asphalt > base asphalt. Among them, the 14# composite modified asphalt had the highest residual penetration ratio, reaching 88.58%, which was 8.92% higher than that of the 4.5% SBS modified asphalt. The 7# composite modified asphalt also had a 7.03% higher residual penetration ratio than the 4.5% SBS modified asphalt. All of them showed good anti-aging performance. These data fully demonstrate that the graphene / SBS composite modified asphalt has significant advantages in anti-aging performance.

[0078] Table 10 Comparison of softening points of asphalt before and after aging

[0079] The softening point increment reflects the extent of change in the high-temperature performance of asphalt after aging. The test results in Table 10 show that there are significant differences in the increase in softening point among the various examples. The 14# composite modified asphalt showed the most significant increase, with a softening point increase of 5.2℃, which is significantly higher than other samples. The base asphalt showed the lowest increase, at only 2.3℃. The softening point increase is ranked from largest to smallest as follows: 14# composite modified asphalt > 7# composite modified asphalt > 0.15% graphene modified asphalt > 4.5% SBS modified asphalt > base asphalt. This data ranking clearly shows that 14# composite modified asphalt has the best anti-aging performance; this is due to the significant synergistic effect of the composite modification system of graphene and SBS; the rigid sheet structure of graphene and the elastic three-dimensional network of SBS interpenetrate with each other to form a more stable composite cross-linking system, which can effectively maintain the integrity of the material and inhibit the degradation of molecular chains during thermo-oxidative aging, thus showing a higher increase in softening point.

[0080] Ductility retention rate reflects the ability of asphalt to retain its low-temperature performance after aging; As shown in Table 11, the ductility loss at 10℃ of the base asphalt was the most significant, with a ductility of only 8.1 cm after aging in a rotating thin-film oven, a decrease of 82.20% compared to the unaged state. In contrast, the ductility loss of the composite modified asphalt was significantly smaller. The order of ductility reduction rate from smallest to largest is: 7# composite modified asphalt < 14# composite modified asphalt < 4.5% SBS modified asphalt < 0.15% graphene modified asphalt < base asphalt. This result demonstrates the superiority of composite modified asphalt in terms of anti-aging performance.

[0081] Table 11 Comparison of Asphalt Ductility Before and After Aging

[0082] (2) Evaluation of high-temperature rheological properties This invention uses a dynamic shear rheometer (DSR) to perform temperature scanning (30~90℃) on asphalt samples before and after aging, and evaluates the high-temperature deformation resistance of the material using the rutting factor (G* / sinδ). The test results are as follows: Figure 4 As shown in the figure, the labels are as follows: J - base asphalt, S - 4.5% SBS modified asphalt, G - 0.15% graphene modified asphalt, 7# - 7# composite modified asphalt, 14# - 14# composite modified asphalt, L - aged sample.

[0083] Depend on Figure 4 It can be seen that, regardless of whether it is before or after aging, the rutting factor of the composite modified asphalt is higher than that of the 4.5% SBS modified asphalt, indicating that the synergistic effect of graphene and SBS significantly optimizes the high-temperature rheological properties of asphalt and improves its resistance to high-temperature rutting.

[0084] (3) Evaluation of low-temperature crack resistance This invention uses the BBR test to evaluate the low-temperature crack resistance of asphalt through flexural creep stiffness modulus S and creep rate m: the S value characterizes the rigidity of the material against load, and the smaller the value, the better the low-temperature flexibility; the m value reflects the stress relaxation ability, and the larger the value, the less stress accumulation and the stronger the crack resistance; according to the Superpave specification, asphalt under low-temperature conditions must meet the requirements of S < 300 MPa and m > 0.3 to ensure that the low-temperature crack resistance of the pavement meets the standard.

[0085] The bending rheometer used in this invention employs pneumatic loading, which enables precise preloading, unloading, and constant load control during the test. The test temperatures were selected as -12℃ and -18℃. The creep stiffness modulus S and creep curve slope m were measured during the test, and the test data are shown in Table 12.

[0086] Table 12 Flexural Creep Properties of Modified Asphalt

[0087] As shown in Table 12, the creep stiffness modulus S of each asphalt sample increases with decreasing temperature, and the creep curve slope m decreases with decreasing temperature, with the base asphalt exhibiting the worst low-temperature performance. Compared to 4.5% SBS modified asphalt, the addition of graphene to the composite modified asphalt increased the creep stiffness modulus and decreased the creep rate, indicating that graphene slightly hardened the SBS modified asphalt at low temperatures. This had a certain negative impact on the low-temperature crack resistance of the SBS modified asphalt, resulting in a decrease in the low-temperature crack resistance of the graphene / SBS composite modified asphalt. However, all tested modified asphalt samples met the low-temperature performance requirements of S < 300 MPa and m > 0.3 under the test conditions of -12℃ and -18℃, indicating that they have good resistance to low-temperature cracking.

[0088] (4) Storage stability analysis This invention uses segregation tests to evaluate the storage stability of modified asphalt. According to the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the softening point difference of polymer-modified asphalt is ≤2.5℃.

[0089] The separation test steps of the present invention are as follows: 50g of test sample is poured into a glass test tube with a diameter of 2.5cm, placed vertically in an oven at 163±5℃ for 48h, taken out and quickly frozen for 4h, the test tube is broken and the test sample is divided into three sections: upper, middle and lower. The softening points at the upper and lower ends are measured, and the stability is evaluated by the difference. The calculation results are shown in Table 13.

[0090] Table 13 Comparison of Segregation Test Results of Modified Asphalt

[0091] As shown in Table 13, the 4.5% SBS modified asphalt has the highest softening point difference due to thermodynamic incompatibility. The softening point of the composite modified asphalt is significantly reduced after the introduction of graphene two-dimensional nanomaterials. The softening points of the 7# and 14# composite modified asphalts are 1.6℃ and 1.9℃, respectively, both of which meet the specifications.

[0092] This is attributed to the fact that graphene's unique layered structure forms a physical barrier in the asphalt system, delaying SBS aggregation; at the same time, its surface polarity enhances the adsorption capacity of SBS; on the other hand, the three-dimensional network structure formed by graphene in the asphalt matrix restricts the free migration of SBS, thereby significantly inhibiting the phase separation process and improving storage stability.

[0093] 5. Based on microstructure characterization and chemical analysis experiments, the modification mechanism of graphene / SBS composite modified asphalt was revealed. The aging process of asphalt materials is not only reflected in the deterioration of macroscopic properties, but also in the changes in their microstructure and chemical composition. In order to reveal the aging mechanism of graphene / SBS composite modified asphalt and the essential reasons for its anti-aging performance, this invention uses scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to analyze and compare five sets of example samples before and after aging for systematic characterization.

[0094] Among them, SEM's high-resolution imaging capability allows for direct observation of the evolution of asphalt surface morphology and the degradation characteristics of modifier network structure during aging; FTIR technology, through precise analysis of characteristic absorption peaks, can accurately identify the chemical bond breakage and oxidation product formation that occur during the aging process of materials; and elucidates its synergistic mechanism from both microscopic morphology and chemical evolution perspectives.

[0095] (1) Microscopic morphological characterization This invention utilizes SEM to directly observe the distribution of modifiers in the asphalt matrix and their interfacial bonding characteristics with asphalt. Sample preparation is a crucial step in ensuring clear visibility of the interface between the modifier particles and the asphalt. The sample preparation process is as follows: Step 1: Heat the asphalt and coat it evenly on the surface of the silicone film. After it cools naturally to room temperature, take out the asphalt sample and fix it on the carbon conductive glass slide. Step 2: Then, the sample surface is sprayed with gold and left to stand at room temperature for 2 hours; Step 3: The surface morphology of the sample was observed and analyzed using an environmental scanning electron microscope; the experimental results are as follows: Figures 5-9 As shown.

[0096] from Figures 5-9 It can be observed that the base bitumen ( Figure 5 The surface of the sample is relatively smooth with few impurities, exhibiting a typical homogeneous structure. 4.5% SBS modified bitumen ( Figure 6 After stirring and shearing, the SBS polymer can be dispersed relatively evenly in the asphalt matrix, mainly in the form of flocculent matter, with a small amount of local accumulation, initially forming an elastic network structure. Graphene-modified asphalt ( Figure 7 In the study, graphene sheets are embedded in the asphalt matrix at the nano to micron scale. The edges of the sheets are continuous and there are no gaps at the interface with the asphalt, indicating that the two are mainly combined through physical intercalation. 7# Composite Modified Asphalt ( Figure 8 The graphene agglomeration phenomenon is significantly reduced, the sheet structure is evenly distributed around the SBS network, and some are coated by SBS polymer, initially forming a two-phase composite structure. 14# Composite Modified Asphalt ( Figure 9 In the graphene sheets and SBS network, the graphene sheets and SBS network interweave and intertwine to form a dense composite structure of "inorganic reinforcing phase + organic elastic phase". The graphene is uniformly dispersed in the SBS network, and the two are tightly bonded at the interface with no obvious phase separation.

[0097] The aforementioned microstructural features indicate that graphene activated by the silane coupling agent KH-550 has good compatibility with SBS, and the two form a stable composite network structure in the asphalt matrix. This structure not only leverages the rigid framework reinforcement of graphene but also retains the elastic network properties of SBS, providing a structural basis for improving macroscopic mechanical properties.

[0098] (2) Analysis of the evolution of functional groups This invention uses a Nicolet iS 50+ Contiuum Fourier transform infrared spectrometer manufactured by Thermo Fisher Scientific, USA, to perform infrared spectral testing on graphene powder and its modified asphalt. The instrument's scanning range was set to 4000–400 cm⁻¹. -1 Its resolution is set to 4cm. -1 The number of scans was set to 32. The preparation process of the Fourier transform infrared spectroscopy test sample is as follows: The preheated asphalt was poured evenly onto the surface of the silicone film and allowed to cool naturally at room temperature. It was then sealed and stored in a vacuum environment to prevent dust from settling on the sample surface.

[0099] Figures 10-11 In the diagram, A represents base asphalt, S represents 4.5% SBS modified asphalt, G represents 0.15% graphene modified asphalt, 7# represents 7# composite modified asphalt, and 14# represents 14# composite modified asphalt.

[0100] from Figure 10 As can be seen, absorption peaks appear in certain locations for each sample, mainly due to the chemical reaction between the matrix bitumen and some hydroxyl groups, for example, at 2921.7 cm⁻¹. -1 2852.9 cm -1 Strong absorption occurs at 1456.8 cm⁻¹, indicating the presence of saturated hydrocarbons; -1 1377.3 cm -1 A strong absorption occurs at 722.1 cm⁻¹, which is the absorption peak of the in-plane bending vibration of aliphatic CH₄. -1 The strong absorption occurs at this point, which is due to the CH bending vibration on the benzene ring.

[0101] After aging in a rotating thin-film oven, the asphalt produced new absorption peaks, such as... Figure 11 As shown, the newly added characteristic absorption peak after aging is located at a wavenumber of 1065.8 cm⁻¹ in the figure. -1 1719.7 cm -1 Location, 1065.8 cm -1 Primarily classified as sulfoxide group (S=O), 1719.7 cm -1 They are mainly classified as ketones (C=O).

[0102] For asphalt materials, C=O and S=O are two important functional groups, and the degree of aging of asphalt can be analyzed by observing the strength changes of these two functional groups.

[0103] This invention imports data into Omnic software, performs calculations according to the formula, and takes three decimal places. The calculation results are shown in Table 14, where R represents the result after aging in a rotating thin film oven.

[0104] Table 14 Calculation Table of ICO and ISO Index for Fourier Transform Infrared Spectra of Asphalt

[0105] As can be seen from Table 14, the ICO (carbonyl index) and ISO (sulfoxide index) values ​​of Examples 1-5 after short-term aging are higher than those of the asphalt before aging, indicating that the asphalt underwent an oxidation reaction during the aging process, resulting in the formation of carbonyl (C=O) and sulfoxide (S=O) functional groups. Comparing the aged base asphalt and modified asphalt, although the ICO and ISO values ​​of the composite modified asphalt increased, they were still less than those of 4.5% SBS modified asphalt. Among them, the ICO and ISO values ​​of 14# composite modified asphalt were the lowest before and after aging, indicating that it had the best anti-aging performance. The ICO and ISO values ​​of 7# composite modified asphalt were also low after aging, indicating that it had good anti-aging performance. Moreover, after short-term aging, the ICO (carbonyl index) and ISO (sulfoxide index) values ​​of all five groups of asphalt were significantly higher than those of the asphalt before aging.

[0106] The above results indicate that the introduction of graphene activated by the silane coupling agent KH-550 effectively inhibits the formation of oxides such as carbonyl and sulfoxide groups in asphalt, significantly delays the oxidative aging process of asphalt, and the inhibitory effect of the composite modification system is better than that of the single modification system.

[0107] (3) Revealing the mechanism of synergistic modification Based on the above-mentioned results of microscopic morphology observation and chemical analysis, the synergistic mechanism of graphene / SBS composite modified asphalt is revealed.

[0108] The two-dimensional sheet structure of graphene forms a dense physical barrier in the asphalt matrix, which is evenly distributed between the SBS network, effectively blocking the intrusion path of aging media such as oxygen and moisture, and slowing down the oxidation reaction rate. SEM images confirm that graphene sheets and SBS networks intertwine to form a dense structure in 14# composite modified asphalt, enhancing the material's barrier properties. The large π-conjugated system of graphene can capture free radicals generated during the thermo-oxidative aging of asphalt, interrupting the chain oxidation reaction and thus inhibiting the formation of oxidation products such as carbonyl and sulfoxide groups. FTIR data show that the functional group index of 14# composite modified asphalt increased the least after aging, which verifies its excellent free radical capture ability; the three-dimensional elastic network formed by SBS not only improves the toughness and crack resistance of asphalt, but also restricts the thermal motion of asphalt molecules and reduces its oxidation activity through physical cross-linking. Meanwhile, the rigid sheets of graphene fill the gaps in the SBS network, and the two reinforce each other to form a composite structure of "physical reinforcement + elastic support". This structure can effectively maintain the integrity of the material and inhibit the degradation of molecular chains during thermo-oxidative aging, thus exhibiting a higher performance retention rate.

[0109] This invention systematically elucidates the synergistic modification mechanism of graphene and SBS in asphalt matrix by combining microstructure characterization and chemical analysis: the nanosheet structure of graphene provides physical barriers and free radical capture functions, while the elastic network of SBS provides structural toughness and stress dispersion capabilities. Together, they construct a multi-scale protection system from nanoscale to macroscale.

[0110] After surface activation treatment with silane coupling agent KH-550, the interfacial compatibility between graphene and SBS is significantly improved, and the dispersion uniformity is enhanced, resulting in a synergistic enhancement effect in terms of anti-aging performance, high-temperature stability, and low-temperature crack resistance of the composite modified asphalt.

[0111] Although adding SBS and graphene increases material costs, the significant improvement in anti-aging and road performance brought by 7# and 14# composite modified asphalt gives them a significant performance-price advantage in demanding application scenarios such as heavy traffic or areas with large temperature differences. Among them, 14# composite modified asphalt (4.5% SBS + 0.15% activated graphene) is particularly suitable for road engineering with extremely high performance requirements due to its optimal comprehensive performance.

[0112] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing graphene / SBS composite modified bitumen, characterized in that, Includes the following steps: S1. Surface activation treatment of graphene: Graphene is surface treated with an alcohol-water solution prepared with silane coupling agent KH-550, and then dried and ground to obtain graphene powder surface activated with silane coupling agent KH-550. S2. Preparation of graphene / SBS composite modified asphalt: The graphene powder and SBS modifier were mixed into the base asphalt by high-speed shearing and uniformly sheared to obtain graphene / SBS composite modified asphalt. S3. Proportioning optimization and performance verification steps: The optimal combination dosage of SBS and graphene was determined through two-component full factorial experimental design to obtain the graphene / SBS composite modified asphalt with the best performance.

2. The method for preparing graphene / SBS composite modified bitumen according to claim 1, characterized in that, In S1, the surface activation treatment of graphene includes the following steps: S11. Preparation of alcohol-water solution: Prepare an alcohol-water solution by mixing anhydrous ethanol and distilled water at a volume ratio of 10:

1. The total amount used is 3 to 5 times the mass of graphene. Place the solution in a beaker for later use. S12. Preparation of coupling agent ethanol solution: Weigh 0.8% of silane coupling agent KH-550 according to the mass of graphene, add it to a beaker containing alcohol aqueous solution and stir until completely dissolved to obtain a uniform coupling agent ethanol solution. S13. Preheating: Place the beaker containing the coupling agent ethanol solution on a temperature-adjustable heater and preheat it to 50~60°C. S14. Preparation of suspension: Slowly add graphene powder to the preheated alcohol-water solution, turn on the stirrer and control the stirring speed to 500~1000 r / min, and continue stirring for 30~40 min under constant temperature conditions to obtain a uniformly mixed suspension. S15. Drying: Transfer the obtained suspension to an oven and dry at 80°C for 12 h to obtain the fixed product; S16. Grind the dried solid product into fine powder to obtain graphene powder that has been surface activated by silane coupling agent KH-550.

3. The method for preparing graphene / SBS composite modified asphalt according to claim 1 or 2, characterized in that, The silane coupling agent KH-550 is γ-aminopropyltriethoxysilane, and its dosage is 5%~10% of the graphene mass. The graphene is a single-layer graphene, and the amount of graphene is 0.05% to 0.2% of the mass of the matrix bitumen.

4. The method for preparing graphene / SBS composite modified bitumen according to claim 1, characterized in that, In S2, the preparation steps of the graphene / SBS composite modified asphalt are as follows: S21. Pre-treatment of base asphalt dehydration: Heat the container containing base asphalt until the base asphalt is in a molten and flowing state, then place the container on an electric furnace lined with asbestos mesh, and heat and stir to evaporate the residual moisture in the base asphalt. S22, SBS Modifier Shear Dispersion: Place the pretreated container containing the base asphalt and the electric furnace together under the high-speed shear machine, add the SBS modifier, and set the rotation speed to 1500 r / min for preliminary shear dispersion. After the SBS particles are initially dispersed evenly, the rotation speed is gradually increased to 4000~7000 r / min, and high-speed shearing is performed for 30~45 min to allow the SBS to fully swell and form a uniform network; S23, Graphene powder shear dispersion: Add graphene powder and continue shear dispersion for 25~35 min, during which the asphalt temperature is controlled at 155~165℃.

5. The method for preparing graphene / SBS composite modified bitumen according to claim 1 or 4, characterized in that, The base asphalt is No. 70 road petroleum asphalt; The SBS modifier is a styrene-butadiene-styrene block copolymer, and the dosage of the SBS modifier is 3.5% to 5.5% of the mass of the base asphalt.

6. The method for preparing graphene / SBS composite modified bitumen according to claim 1, characterized in that, In step S3, the ratio optimization and performance verification steps are as follows: S31. The optimal combination dosage of SBS and graphene was determined by two-component full factorial experimental design. The dosage levels of SBS modifier were selected as 3.5%, 4%, 4.5%, 5%, and 5.5%, and the dosage levels of graphene were selected as 0%, 0.05%, 0.1%, 0.15%, and 0.2%. 25 groups of graphene / SBS composite modified asphalt samples with different ratios were prepared. S32. By comprehensively evaluating the basic performance indicators of each group of samples, the optimal combination ratio with the best overall performance is selected. S33. The anti-aging ability, rheological properties and storage stability of composite modified asphalt were verified by using rotating thin film oven aging test, dynamic shear rheology test, bending beam rheology test and segregation test.

7. The method for preparing graphene / SBS composite modified bitumen according to claim 1, characterized in that, The basic performance indicators include penetration, softening point, and ductility; The evaluation indicators for the aging test of the rotating thin film oven include mass loss, residual penetration ratio, ductility retention rate, and softening point increment; The dynamic shear rheological test uses the rutting factor G* / sinδ to evaluate the high-temperature deformation resistance of the material. The bending beam rheological test evaluated the low-temperature crack resistance of asphalt using creep stiffness modulus S and creep rate m. The segregation test evaluates storage stability using the difference in softening point, and the difference in softening point is required to be no greater than 2.5℃.

8. A graphene / SBS composite modified asphalt, characterized in that, The preparation method according to any one of claims 1 to 7 is used, wherein the SBS content is 4.5% and the graphene content is 0.15%.

9. The graphene / SBS composite modified asphalt according to claim 8, characterized in that, Oxygen-containing functional groups were grafted onto the surface of graphene after surface activation treatment with silane coupling agent KH-550. The silane coupling agent KH-550 contains an inorganic-loving triethoxysilane and an organic-loving amino group in its molecular structure. In an alcohol-water system, the triethoxysilane hydrolyzes to generate a silanol structure. The silanol undergoes a condensation reaction with the hydroxyl groups on the graphene surface to form a covalent bond, and the amino group endows the graphene surface with organic active sites.

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