SBS modified asphalt mixture and preparation method thereof

Abstract

The invention discloses an SBS modified asphalt mixture and a preparation method thereof. The mixture is prepared by mixing a composite aggregate system and SBS modified asphalt according to an asphalt-aggregate ratio of 4.5-5.5%, the SBS modified asphalt is prepared by swelling base asphalt, 4 to 5 weight percent of linear SBS, 0.3 to 0.4 weight percent of BPO, 0.2 to 0.3 weight percent of BPA and 2 weight percent of environment-friendly aromatic oil at the temperature of 45 DEG C for 150 minutes. The problems that existing SBS modified asphalt is slow in swelling, weak in interface adhesion and poor in skeleton stability are solved, the swelling efficiency is improved by 40%, the interface adhesion work reaches 305 mJ / m < 2 > or above, the anti-rutting coefficient is improved by 50%, and the SBS modified asphalt is suitable for high-grade highway pavement engineering.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, specifically to an SBS modified asphalt mixture with high production efficiency, strong interfacial adhesion and stable skeleton structure, and its preparation method. Background Technology

[0002] SBS modified asphalt is widely used in pavement engineering due to its excellent rutting and cracking resistance. However, existing technologies have three major problems: First, SBS has a slow swelling rate in asphalt (usually requiring more than 210 minutes), resulting in long production cycles and high energy consumption. Second, the interfacial adhesion strength between asphalt and aggregate is significantly affected by the aggregate composition. Conventional aggregates (such as single SiO2) are prone to interfacial delamination, leading to water damage. Third, the stability of the asphalt mixture skeleton depends on the aggregate gradation. Existing gradation designs do not take into account the interfacial adhesion characteristics and swelling modification requirements, resulting in low transport efficiency of the main matrix chain (MFC), which easily leads to rutting and cracking under long-term loads.

[0003] Existing technologies suffer from three major bottlenecks: First, SBS molecular chains are relatively long, resulting in a slow swelling rate in asphalt, with conventional swelling times exceeding 210 minutes, leading to long production cycles and high energy consumption. Second, the interfacial adhesion between asphalt and aggregates depends on the aggregate chemical composition; single SiO2 aggregates exhibit weak interfacial adhesion, making them susceptible to moisture erosion and delamination, causing pavement water damage. Third, the skeletal stability of asphalt mixtures is determined by aggregate gradation; existing gradation designs do not coordinate interfacial adhesion characteristics with swelling modification requirements, resulting in low main chain (MFC) transport efficiency and susceptibility to rutting, cracking, and other defects after prolonged exposure to vehicle loads. In summary, existing technologies fail to organically combine aggregate composition optimization, gradation design, and SBS swelling acceleration technology, hindering breakthroughs in the overall performance of modified asphalt mixtures. Therefore, this application proposes an SBS-modified asphalt mixture and its preparation method to at least partially address the problems inherent in existing technologies. Summary of the Invention

[0004] To overcome or at least partially solve the above problems, embodiments of the present invention provide an SBS-modified asphalt mixture and its preparation method. It has advantages such as high production efficiency, strong interfacial adhesion, and a stable skeleton structure.

[0005] An SBS-modified asphalt comprises a composite aggregate system and SBS-modified asphalt, wherein the composite aggregate system and SBS-modified asphalt are mixed at an asphalt-aggregate ratio of 4.5-5.5%.

[0006] The composite aggregate system comprises, by mass percentage: Al2O3 60-80%, CaCO3 10-20%, and SiO2 5-10%.

[0007] The composite aggregate has the following gradation by mass percentage: >9.5mm 15-25%, 2.36-9.5mm 50-60%, 1.18-2.36mm 10-20%, and 0.6-1.18mm 5-10%.

[0008] The SBS modified asphalt comprises, by mass percentage: 88.7-90.7% base asphalt and linear SBS.

[0009] 4-5%, BPO 0.3-0.4%, BPA 0.2-0.3%, and environmentally friendly aromatic oil 2%.

[0010] Furthermore, the penetration of the base asphalt is 70-90 dmm (25℃), and the softening point is 46-48℃.

[0011] Furthermore, the environmentally friendly aromatic oil is a naphthenic aromatic oil or a paraffinic aromatic oil, with an aromatic hydrocarbon content of ≥60%.

[0012] Furthermore, the purity of Al2O3 in the composite aggregate is ≥95%, the purity of CaCO3 is ≥90%, and the particle size of SiO2 is 0.6-1.18 mm.

[0013] Furthermore, the linear SBS has a styrene content of 30-35% and a number-average molecular weight of 100,000-200,000.

[0014] A method for preparing SBS modified asphalt mixture includes the following steps:

[0015] (1) Preparation of SBS modified asphalt: Heat the base asphalt to 110-120℃, add linear SBS, BPO, BPA and environmentally friendly aromatic oil, stir evenly and then swell at 40-45℃ for 140-160 minutes to obtain SBS modified asphalt.

[0016] (2) Pre-treatment of aggregates: After mixing the composite aggregates according to the gradation, heat to 160-170℃ and keep warm for 20-40 minutes;

[0017] (3) Mixing and molding: Heat the SBS modified asphalt from step (1) to 150-160℃, mix it with the pretreated aggregate from step (2) according to the preset asphalt-aggregate ratio, shear it at 4000-6000r / min for 25-35 minutes, and compact it using a Superpave rotary compactor to obtain the SBS modified asphalt mixture.

[0018] Furthermore, the step of preparing SBS-modified asphalt includes:

[0019] Heat the base asphalt to 110-120℃, add linear SBS, BPO, BPA and environmentally friendly aromatic oil, and stir at a stirring speed of 500-800r / min for 10-15 minutes to obtain a uniformly stirred intermediate.

[0020] The intermediate was swelled at a constant temperature of 40-45℃ for 140-160 minutes to obtain SBS modified asphalt.

[0021] Furthermore, the pretreatment step of the aggregate includes:

[0022] After the composite aggregates are mixed according to their gradation, they are heated in stages. Specifically, the temperature is first raised to 120℃ and held for 10 minutes, and then raised to 160-170℃ and held for 20-40 minutes.

[0023] Furthermore, the mixing and molding step includes:

[0024] SBS modified asphalt is heated to 150-160℃ and mixed with pretreated aggregate at a preset asphalt-aggregate ratio. It is then sheared at high speed at 4000-6000 r / min for 25-35 minutes. The mixture is then compacted 90-110 times using a Superpave rotary compactor at a compaction temperature of 150-155℃. The mixture is then compacted and shaped to obtain the SBS modified asphalt mixture.

[0025] Furthermore, the rutting resistance coefficient of the mixture in a 60°C environment is ≥8.5 kN·s / m. 2 In an environment of -10℃, the ductility is ≥18cm, and the softening point increase after RTFOT aging is ≤5.5℃;

[0026] The porosity of the mixture is 3-5%, and the thickness of the asphalt film on the aggregate surface is 6-10 μm.

[0027] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0028] This application addresses several issues: firstly, the slow swelling and low production efficiency of SBS modified asphalt; secondly, the insufficient adhesion between asphalt and aggregate, leading to delamination and water damage; thirdly, the low transport efficiency and poor long-term stability of the MFC (Medium-Fluid Composite) aggregate skeleton; and fourthly, the difficulty in simultaneously achieving good aging resistance and high / low temperature performance in modified asphalt. This application boasts high swelling efficiency: swelling time is reduced from 210 minutes to 140-160 minutes, increasing production efficiency by 40% and diffusion coefficient by 76%; and good interfacial adhesion: the Al2O3-dominated composite aggregate achieves an interfacial adhesion work of 305 mJ / m. 2 The peeling rate is reduced by 60%; the skeleton has strong stability: the MFC ratio is increased to over 60%, and the rutting resistance coefficient (60℃) is ≥8.5kN·s / m.2 Low temperature (-10℃) ductility ≥18cm; good durability: softening point increase after RTFOT aging ≤5.5℃, ductility retention rate after PAV aging increased by 40%. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 An aggregate gradation curve of an SBS modified asphalt mixture is provided as an embodiment of the present invention;

[0031] Figure 2 This is a molecular dynamics simulation diagram of the swelling process of an SBS modified asphalt mixture provided in an embodiment of the present invention;

[0032] Figure 3 This is a molecular model diagram of the asphalt-aggregate interface of an SBS modified asphalt mixture provided in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the various embodiments and features described below can be combined with each other.

[0035] An SBS-modified asphalt mixture comprises a composite aggregate system and SBS-modified asphalt. The composite aggregate system and SBS-modified asphalt are mixed at an asphalt-aggregate ratio of 4.5-5.5%. The composite aggregate system comprises, by mass percentage: Al₂O₃ 60-80%, CaCO₃ 10-20%, and SiO₂ 5-10%. The gradation of the composite aggregate comprises, by mass percentage: >9.5mm 15-25%, 2.36-9.5mm 50-60%, 1.18-2.36mm 10-20%, and 0.6-1.18mm 5-10%. The SBS-modified asphalt comprises, by mass percentage: base asphalt 88.7-90.7%, linear SBS 4-5%, BPO 0.3-0.4%, BPA 0.2-0.3%, and environmentally friendly aromatic oil 2%.

[0036] The base asphalt has a penetration of 70-90 dmm (25℃) and a softening point of 46-48℃.

[0037] The environmentally friendly aromatic oil is a naphthenic aromatic oil or a paraffinic aromatic oil, with an aromatic hydrocarbon content of ≥60%.

[0038] The composite aggregate contains Al2O3 with a purity of ≥95%, CaCO3 with a purity of ≥90%, and SiO2 with a particle size of 0.6-1.18 mm.

[0039] The linear SBS contains 30-35% styrene and has a number-average molecular weight of 100,000-200,000.

[0040] The preparation method of SBS modified asphalt mixture includes the following steps:

[0041] (1) Preparation of SBS modified asphalt: Heat the base asphalt to 110-120℃, add linear SBS, BPO, BPA and environmentally friendly aromatic oil, and stir at a stirring speed of 500-800r / min for 10-15 minutes to obtain a uniformly stirred intermediate.

[0042] The intermediate was swelled at a constant temperature of 40-45℃ for 140-160 minutes to obtain SBS modified asphalt.

[0043] (2) Pre-treatment of aggregates: After the composite aggregates are mixed according to the gradation, they are heated in stages. Specifically, the temperature is first raised to 120℃ and kept for 10 minutes, and then raised to 160-170℃ and kept for 20-40 minutes.

[0044] (3) Mixing and molding: Heat the SBS modified asphalt to 150-160℃ and mix it with the pretreated aggregate according to the preset asphalt-aggregate ratio. Shear at high speed of 4000-6000r / min for 25-35 minutes. Use a Superpave rotary compactor to perform rotary compaction 90-110 times at a compaction temperature of 150-155℃. Obtain the SBS modified asphalt mixture through compaction molding.

[0045] Furthermore, the rutting resistance coefficient of the mixture in a 60°C environment is ≥8.5 kN·s / m. 2 The ductility at -10℃ is ≥18cm, and the softening point increase after RTFOT aging is ≤5.5℃.

[0046] The porosity of the mixture is 3-5%, and the thickness of the asphalt film on the aggregate surface is 6-10 μm.

[0047] Example 1: Composite aggregate system (mass percentage): Al2O3 70% (purity 96%), CaCO3 15% (purity 92%), SiO2 15% (particle size 0.6-1.18mm);

[0048] Aggregate gradation (by weight): >9.5mm 20%, 2.36-9.5mm 55%, 1.18-2.36mm 15%, 0.6-1.18mm 10%;

[0049] SBS modified bitumen formulation (by weight): base bitumen (penetration 80 dmm, softening point 47℃) 90%, linear SBS (styrene content 32%, number average molecular weight 150,000) 4.5%, BPO 0.3%, BPA 0.2%, naphthenic aromatic oil (aromatic content 65%) 2%; where styrene is styrene.

[0050] Preparation process:

[0051] (1) Heat the base asphalt to 115°C, add SBS, BPO, BPA and aromatic oil, stir at 500r / min for 12 minutes, and swell at 45°C for 150 minutes to obtain SBS modified asphalt.

[0052] (2) Segmented heating of aggregate: keep at 120℃ for 10 minutes, then keep at 165℃ for 30 minutes;

[0053] (3) The modified asphalt is heated to 155°C and mixed with aggregate at an asphalt-aggregate ratio of 5.0%. It is sheared at 5000r / min for 30 minutes and then compacted by Superpave rotary compaction (100 times, 152°C) to form the shape.

[0054] It should be noted that in this embodiment, the preset asphalt-aggregate ratio is 4.5-5.5%, and the optimal implementation ratio is 5.0%. This range is precisely determined based on the characteristics of composite aggregates, the swelling state of SBS modified asphalt, and the requirements of the mixture skeleton. It can be finely adjusted within the above range according to the actual climatic conditions and traffic load level of the project (e.g., 5.0-5.5% for heavy-load road sections and 4.5-5.0% for light-traffic road sections).

[0055] Example 2: Composite aggregate system (mass percentage): Al2O3 80% (purity 97%), CaCO3 10% (purity 91%), SiO2 10% (particle size 0.6-1.18mm);

[0056] Aggregate gradation (by weight): >9.5mm 25%, 2.36-9.5mm 50%, 1.18-2.36mm 15%, 0.6-1.18mm 10%;

[0057] SBS modified bitumen formulation (mass percentage): base bitumen (penetration 75dmm, softening point 46℃) 89.3%, linear SBS (styrene content 35%, number average molecular weight 200,000) 5%, BPO 0.4%, BPA 0.3%, paraffinic aromatic oil (aromatic content 60%) 2%.

[0058] Preparation process:

[0059] (1) Heat the base asphalt to 120°C, add SBS, BPO, BPA and aromatic oil, stir at 800r / min for 10 minutes, and swell at 40°C for 160 minutes to obtain SBS modified asphalt.

[0060] (2) Segmented heating of aggregate: keep at 120℃ for 10 minutes, then keep at 170℃ for 20 minutes;

[0061] (3) The modified asphalt is heated to 160°C and mixed with aggregate at an asphalt-aggregate ratio of 5.5%. It is sheared at 6000r / min for 25 minutes and then compacted by Superpave rotary compaction (110 times, 155°C) to form the shape.

[0062] Example 3: Composite aggregate system (mass percentage): Al2O3 60% (purity 95%), CaCO3 20% (purity 90%), SiO2 10% (particle size 0.6-1.18mm);

[0063] Aggregate gradation (by weight): >9.5mm 15%, 2.36-9.5mm 60%, 1.18-2.36mm 20%, 0.6-1.18mm 5%;

[0064] SBS modified bitumen formulation (mass percentage): base bitumen (penetration 90 dmm, softening point 48℃) 90.7%, linear SBS (styrene content 30%, number average molecular weight 100,000) 4%, BPO 0.3%, BPA 0.2%, naphthenic aromatic oil (aromatic content 68%) 2%.

[0065] Preparation process:

[0066] (1) Heat the base asphalt to 110°C, add SBS, BPO, BPA and aromatic oil, stir at 600r / min for 15 minutes, and swell at 43°C for 140 minutes to obtain SBS modified asphalt.

[0067] (2) Segmented heating of aggregate: keep at 120℃ for 10 minutes, then keep at 160℃ for 40 minutes;

[0068] (3) The modified asphalt is heated to 150°C and mixed with aggregate at an asphalt-aggregate ratio of 4.5%. It is sheared at 4000r / min for 35 minutes and then compacted by Superpave rotary compaction (90 times, 150°C) to form the shape.

[0069] Comparative Example 1: Detailed Data Sheet of the Embodiment

[0070]

[0071] Table 1

[0072] Table 1 above is a detailed data table of the comparative example.

[0073] The composite aggregate system in this application uses Al2O3 (60-80% by mass, purity ≥95%) as the main aggregate, which utilizes its strong polar Al-O bonds to form strong dipole interactions with resin and aromatic molecules in asphalt; the auxiliary aggregate CaCO3 (10-20%, purity ≥90%) balances cost and adhesion, and SiO2 (5-10%, particle size 0.6-1.18mm) optimizes the pore structure of the skeleton and improves the density of the mixture.

[0074] The aggregate gradation design incorporates a gradation pattern for efficient MFC transport, controlling the proportion of aggregates >9.5mm to 15-25% (strengthening the skeleton support), 2.36-9.5mm aggregates to 50-60% (dominantly forming MFC), 1.18-2.36mm aggregates to 10-20% (filling skeleton voids), and 0.6-1.18mm aggregates to 5-10% (auxiliary filling), thereby increasing the MFC ratio to over 60%.

[0075] Preparation of SBS modified asphalt: The base asphalt is selected as road petroleum asphalt with a penetration of 70-90 dmm and a softening point of 46-48℃. 4-5 wt% linear SBS (styrene content 30-35%, number average molecular weight 100,000-200,000), 0.3-0.4 wt% BPO (free radical initiator), 0.2-0.3 wt% BPA (free radical stabilizer) and 2 wt% environmentally friendly aromatic oil (cycloalkyl or paraffinic, aromatic content ≥60%) are added. The mixture is swelled at 40-45℃ for 140-160 minutes. The free radicals generated by the decomposition of BPO relax the SBS network, and BPA captures excess free radicals to prevent excessive cross-linking of SBS, synergistically accelerating the diffusion of light components of asphalt into the interior of SBS.

[0076] Mixture preparation process: Aggregates are heated in stages (first at 120℃ for 10 minutes, then at 160-170℃ for 20-40 minutes), modified asphalt is preheated to 150-160℃, mixed at an asphalt-aggregate ratio of 4.5-5.5%, high-speed sheared at 4000-6000r / min for 25-35 minutes, and compacted using a Superpave rotary compactor (90-110 times, 150-155℃).

[0077] like Figure 1 As shown, this is the aggregate gradation curve of this application. The horizontal axis represents the sieve aperture size (mm), and the vertical axis represents the passing rate (%). The curve clearly shows the proportion distribution of the four particle size ranges: >9.5mm, 2.36-9.5mm, 1.18-2.36mm, and 0.6-1.18mm, reflecting the collaborative design of "skeleton-filler" to ensure efficient MFC transmission.

[0078] Among them, the AC series curves (AC10, AC13, AC16) refer to asphalt concrete; the SMA series curves (SMA10, SMA13, SMA16) refer to stone mastic asphalt; and the OGFC series curves (OGFC10, OGFC13, OGFC16) refer to open-graded asphalt friction courses.

[0079] like Figure 2 The figure shown is a molecular dynamics simulation diagram of the swelling process of SBS modified asphalt mixture in this application. In the figure, A1-A4 are conventional swelling systems, and B1-B4 are the accelerated swelling systems of this invention. As can be seen from the comparison, the SBS molecular chains in B4 are more fully expanded, and the light asphalt components diffuse more evenly inside the SBS, which verifies the swelling acceleration effect of BPO / BPA.

[0080] like Figure 3 The figure shown is the molecular model of the asphalt-aggregate interface of this application, wherein, Figure 3b is the interface model between Al2O3 aggregate and the SBS modified asphalt of this invention. It can be seen that the resin and aromatic molecules in the asphalt form a high-concentration adsorption layer on the surface of Al2O3, and the interface is more tightly bound, which confirms the improvement of the interface adhesion strength.

[0081] Compared with existing technologies, this method achieves simultaneous improvement in swelling efficiency, interfacial adhesion, and skeleton stability through a reasonable combination of technologies, and the effects are not simply additive. Optimizing parameters for different application scenarios (such as using a high Al2O3 ratio and high SBS molecular weight for high-load pavements) solves the problem of poor parameter versatility in existing technologies, achieving a "customized" technical effect. Process optimizations such as segmented heating and specific compaction temperatures avoid secondary problems such as uneven aggregate heating and thermal aging of modified asphalt, further improving the overall performance of the mixture and demonstrating in-depth consideration of technical details.

[0082] Table 2 below shows the data comparison table.

[0083] Example 1 2 3 Oil-stone ratio (%) 5.0 4.2 8.5 Porosity (%) 5.5 3.5 9.8 Asphalt film thickness (μm) 4.5 4.8 7.2

[0084] Table 2 shows the porosity and asphalt film thickness data corresponding to the specified oil-aggregate ratio in Examples 1-3.

[0085] The specific surface area of ​​Al2O3-CaCO3-SiO2 composite aggregate (due to the high polarity of Al2O3 and the large number of active sites on the particle surface) is higher than that of single aggregate. A 4.5-5.5% asphalt-aggregate ratio ensures the formation of a uniform 6-10 μm asphalt film on the aggregate surface (compared to a conventional 3.8-4.2% asphalt-aggregate ratio). This avoids interfacial peeling caused by an excessively thin asphalt film, while preventing rutting risks caused by an excessively thick film, thus stabilizing the interfacial adhesion work at 305 mJ / m. 2 above.

[0086] Adapted to the viscosity of modified asphalt after accelerated swelling with BPO / BPA: After synergistic swelling with BPO / BPA, the equilibrium viscosity of SBS modified asphalt is increased by 39% compared to the conventional asphalt. A 4.5-5.5% asphalt-aggregate ratio can match this viscosity characteristic, ensuring that the asphalt can fully coat the aggregate during high-speed shearing (4000-6000 r / min), avoiding uneven dispersion and local "dry material" problems caused by high viscosity.

[0087] The gradation design in this application primarily uses 2.36-9.5mm aggregate (50-60%), and the 4.5-5.5% asphalt-aggregate ratio precisely fills the aggregate gaps, controlling the porosity of the mixture at 3-5%. This ensures the continuity of the MFC network (≥60%) while avoiding water damage caused by excessive porosity, and simultaneously improves the rutting resistance coefficient to 8.5 kN·s / m. 2 above.

[0088] The above-mentioned parameters of oil-aggregate ratio and swelling temperature of 40-45℃, along with the synergistic effect of linear SBS (30-35% styrene content), can result in a mixture with a ductility ≥18cm at -10℃ (low-temperature crack resistance) and a rutting resistance coefficient ≥8.5kN·s / m at 60℃. 2 (High temperature resistance to deformation) solves the problem of "one thing being neglected while another is achieved" in conventional asphalt-stone ratio.

[0089] To facilitate understanding of the solutions in this application, the following provides a simple explanation and examples of the terms or highly technical vocabulary used in this field.

[0090] Aggregate gradation: Simply put, aggregate gradation refers to the proportion of aggregate particles of different sizes mixed together, similar to the ratio of large bricks, small stones, and sand when building a house. A proper ratio ensures a more stable structure. For example, the aggregate gradation in this application is precisely designed as follows: large aggregate particles larger than 9.5mm account for 20%, medium aggregate particles of 2.36-9.5mm account for 55%, small aggregate particles of 1.18-2.36mm account for 15%, and fine aggregate particles of 0.6-1.18mm account for 10%. This combination allows the mixture to be both strong and efficiently transfer loads, avoiding the problem of uneven stress distribution in certain areas.

[0091] Asphalt-aggregate ratio: The asphalt-aggregate ratio refers to the percentage of the mass of asphalt (commonly known as "oil") to the total mass of aggregate (commonly known as "stone"). It's like the ratio of water to flour when kneading dough; a proper ratio ensures the dough has the right consistency and texture. In this application, the asphalt-aggregate ratio is controlled at 4.5-5.5%, for example, 100kg of aggregate with 5kg of asphalt. This ratio allows the asphalt to evenly coat the aggregate surface, forming an asphalt film of suitable thickness. It avoids the risk of a "dry" interface peeling due to too little asphalt, and the risk of "sticky" rutting due to too much asphalt.

[0092] Main Component Chain (MFC): The main component chain (MFC) is the "force-bearing chain formed by the contact between aggregate particles" in the mixture. It is equivalent to the "main force" for transmitting vehicle loads, similar to the "force transmission chain formed by people holding hands" when queuing. It can quickly transfer the pressure from above to the structural layer below. In this application, by optimizing the aggregate gradation, the proportion of MFC reaches more than 60%. When vehicles drive on the road surface, the load can be quickly and evenly transmitted through these "chains", and the road surface is less prone to deformation such as ruts and depressions.

[0093] Interfacial adhesion work: Interfacial adhesion work is a core indicator for measuring how well asphalt and aggregate bond together, and its unit is mJ / m. 2A higher value indicates a stronger bond, making it less likely to be washed away by rain or separated by vehicle loads, similar to the strength of glue on wood; the stronger the bond, the harder it is to separate the wood. In this application, a composite aggregate primarily composed of Al2O3 is used, achieving an interfacial adhesion work of 305 mJ / m². 2 The adhesion strength is increased by 66% compared to that of single SiO2 aggregate, which can effectively prevent potholes, peeling and other defects on the road surface in rainy weather.

[0094] Swelling (SBS swelling): Swelling refers to the process by which SBS (a rubber-based modifier) ​​slowly absorbs the "light components" in asphalt when soaked in it, thus expanding and unfolding, making the originally hard asphalt more resilient and elastic, similar to the process of a "sponge expanding and softening when soaked in water." In this application, BPO / BPA synergistic acceleration technology is used to shorten the conventional swelling time of 210 minutes to 150 minutes. After the SBS has fully expanded, the asphalt's low-temperature crack resistance and high-temperature deformation resistance will be significantly improved, allowing the road surface to resist both low-temperature cracking in winter and high-temperature rutting in summer.

[0095] Superpave rotary compaction: Superpave rotary compaction is a professional method for preparing mixture specimens. Simply put, it uses rotational pressure to compact the mixture, simulating the effect of actual road surface compaction by a road roller, similar to "pressing dough by hand to make it more compact and structurally stable." The compaction parameters in this application are set at 90-110 cycles, a compaction temperature of 150-155℃, and the resulting mixture has a porosity controlled at 3-5%, consistent with the density of actual road surfaces, thus accurately reflecting the performance of the road surface.

[0096] Naphthenic aromatic oil: Naphthenic aromatic oil is an auxiliary additive whose core function is to better mix and blend SBS and asphalt, preventing "separation and clumping," similar to "adding cooking oil when kneading dough to make it smoother, less sticky, and improve its taste." In this application, the selected naphthenic aromatic oil has an aromatic hydrocarbon content of ≥60%, and when added to the asphalt at a ratio of 2%, it ensures that SBS is evenly dispersed in the asphalt, preventing the formation of "rubber lumps" and ensuring the stable and consistent performance of the modified asphalt.

[0097] RTFOT Aging Test: The RTFOT aging test simulates the aging process of asphalt mixtures during road construction. Specifically, it tests the performance changes of asphalt after aging by heating at high temperatures and exposing it to air, similar to "baking bread in an oven for a while and seeing if it hardens or becomes brittle, thus judging the bread's resistance to aging." The modified asphalt in this application, after undergoing the RTFOT aging test, showed a softening point increase of ≤5.5℃, which is 30% lower than that of conventional mixtures. This indicates that the asphalt is less prone to aging and becoming brittle during the heating process and can better retain its original properties.

[0098] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0099] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0100] The above provides a detailed description of an SBS modified asphalt mixture and its preparation method provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An SBS-modified asphalt mixture, characterized in that, It includes a composite aggregate system and SBS modified asphalt, wherein the composite aggregate system and SBS modified asphalt are mixed at an asphalt-aggregate ratio of 4.5-5.5%. The composite aggregate system comprises, by mass percentage: Al2O3 60-80%, CaCO3 10-20%, and SiO2 5-10%. The gradation of the composite aggregate by mass percentage is as follows: >9.5mm 15-25%, 2.36-9.5mm 50-60%, 1.18-2.36mm 10-20%, 0.6-1.18mm 5-10%; The SBS modified bitumen comprises, by weight percentage: 88.7-90.7% base bitumen, 4-5% linear SBS, 0.3-0.4% BPO, 0.2-0.3% BPA, and 2% environmentally friendly aromatic oil.

2. The SBS-modified asphalt mixture according to claim 1, characterized in that, The base asphalt has a penetration of 70-90 dmm and a softening point of 46-48℃.

3. The SBS-modified asphalt mixture according to claim 1, characterized in that, The environmentally friendly aromatic oil is a naphthenic aromatic oil or a paraffinic aromatic oil, with an aromatic hydrocarbon content of ≥60%.

4. The SBS-modified asphalt mixture according to claim 1, characterized in that, The composite aggregate has an Al2O3 purity of ≥95%, a CaCO3 purity of ≥90%, and a SiO2 particle size of 0.6-1.18 mm.

5. The SBS-modified asphalt mixture according to claim 1, characterized in that, The linear SBS has a styrene content of 30-35% and a number-average molecular weight of 100,000-200,000.

6. A method for preparing the SBS-modified asphalt mixture according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of SBS modified asphalt: Heat the base asphalt to 110-120℃, add linear SBS, BPO, BPA and environmentally friendly aromatic oil, stir evenly and then swell at 40-45℃ for 140-160 minutes to obtain SBS modified asphalt. (2) Pre-treatment of aggregates: After mixing the composite aggregates according to the gradation, heat to 160-170℃ and keep warm for 20-40 minutes; (3) Mixing and molding: Heat the SBS modified asphalt from step (1) to 150-160℃, mix it with the pretreated aggregate from step (2) according to the preset asphalt-aggregate ratio, shear it at 4000-6000r / min for 25-35 minutes, and compact it using a Superpave rotary compactor to obtain the SBS modified asphalt mixture.

7. The preparation method according to claim 6, characterized in that, The preparation of SBS modified asphalt includes: Heat the base asphalt to 110-120℃, add linear SBS, BPO, BPA and environmentally friendly aromatic oil, and stir at a stirring speed of 500-800r / min for 10-15 minutes to obtain a uniformly stirred intermediate. The intermediate was swelled at a constant temperature of 40-45℃ for 140-160 minutes to obtain SBS modified asphalt.

8. The preparation method according to claim 6, characterized in that, The pretreatment steps for aggregates include: After the composite aggregates are mixed according to their gradation, they are heated in stages. Specifically, the temperature is first raised to 120℃ and held for 10 minutes, and then raised to 160-170℃ and held for 20-40 minutes.

9. The preparation method according to claim 6, characterized in that, The hybrid molding includes: SBS modified asphalt is heated to 150-160℃ and mixed with pretreated aggregate at a preset asphalt-aggregate ratio. It is then sheared at 4000-6000 r / min for 25-35 minutes and compacted 90-110 times using a Superpave rotary compactor at a compaction temperature of 150-155℃. The mixture is then compacted and shaped to obtain the SBS modified asphalt mixture.

10. The preparation method according to claim 6, characterized in that, The mixture exhibits a rutting resistance coefficient ≥8.5 kN·s / m in a 60°C environment. 2 In an environment of -10℃, the ductility is ≥18cm, and the softening point increase after RTFOT aging is ≤5.5℃; The porosity of the mixture is 3-5%, and the thickness of the asphalt film on the aggregate surface is 6-10 μm.

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