Anti-cracking asphalt mixture and method for preparing the same

Abstract

The application relates to the technical field of asphalt mixtures, and particularly discloses an anti-cracking asphalt mixture and a preparation method thereof. A raw material of an anti-cracking asphalt mixture comprises the following components in parts by weight: modified SBS asphalt 10-15 parts; coarse aggregate 60-70 parts; fine aggregate 20-30 parts; basalt fiber 2-5 parts; steel fiber 1-3 parts; silicon-calcium composite filler 3-7 parts; limestone powder 4-8 parts; rubber powder 3-5 parts; and silane coupling agent 0.5-1.5 parts. The modified SBS asphalt is obtained by modifying matrix asphalt through SBS modifier and organic nano-montmorillonite. The asphalt mixture realizes the performance balance of anti-cracking and high-temperature stability, and improves the anti-cracking and high-temperature stability of the anti-cracking asphalt mixture.

Description

Technical Field

[0001] This application relates to the field of asphalt mixture technology, and more specifically, to a crack-resistant asphalt mixture and its preparation method. Background Technology

[0002] Asphalt mixtures, as the core paving material for road engineering, are composed of aggregates, asphalt binders, mineral powder, and necessary additives mixed in a specific ratio. Due to their excellent mechanical properties, ease of construction, and driving comfort, they are used in various transportation infrastructures such as highways and urban arterial roads. Their performance directly determines the service life and traffic quality of roads, requiring simultaneous performance in multiple areas, including low-temperature crack resistance, high-temperature rutting resistance, water stability, and fatigue durability. With increasingly heavy traffic loads and frequent extreme weather events, traditional asphalt mixtures are prone to cracking and rutting during service, especially transverse cracks caused by volume shrinkage in low-temperature environments and fatigue cracking under long-term loads. These issues severely affect the structural integrity of roads and driving safety. Therefore, the development of high-performance crack-resistant asphalt mixtures has become a key direction for technological breakthroughs in the industry.

[0003] In related technologies, such as the patent document with publication number CN115716725B, a crack-resistant asphalt mixture and its preparation method are disclosed. This mixture, by weight, comprises: 7-10 parts base asphalt, 60-70 parts coarse aggregate, 25-35 parts fine aggregate, 4.5-6 parts impermeable fiber filler, 3-5 parts reinforcing joint filler, 5-8 parts mineral powder, and 2-3 parts asphalt oil. The impermeable fiber filler and reinforcing joint filler are compounded, forming an interactive network structure with certain elasticity and water absorption and expansion properties in the pavement after paving. This resists pavement deformation and cracking, while simultaneously absorbing water and expanding to fill pavement voids, preventing water seepage into the pavement and generating dynamic water pressure and pumping, thus preventing severe deterioration of the pavement after the initial aging cracks appear.

[0004] However, the aforementioned crack-resistant asphalt mixture still has significant defects in performance balance. Because it uses base asphalt as the binder and adds asphalt oil to optimize workability, the base asphalt itself has weak high-temperature deformation resistance, and the asphalt oil further reduces the high-temperature rigidity of the binder. Simultaneously, the impermeable fiber filler softens easily in high-temperature environments, and the interactive network support structure originally used for crack resistance will fail due to fiber stiffness reduction. Furthermore, the interfacial bonding compatibility between the reinforced node filler and the base asphalt is insufficient, and the decreased bonding strength at high temperatures easily leads to a loose aggregate skeleton. Under high summer temperatures or long-term compaction by heavy vehicles, it suffers from insufficient resistance to permanent deformation. Therefore, the asphalt mixture in the above scheme performs poorly in terms of high-temperature stability and is difficult to meet the requirements of heavy-duty traffic conditions. Summary of the Invention

[0005] To improve the high-temperature stability of crack-resistant asphalt mixtures, this application provides a crack-resistant asphalt mixture and its preparation method.

[0006] The crack-resistant asphalt mixture provided in this application adopts the following technical solution:

[0007] A crack-resistant asphalt mixture comprises the following raw materials in parts by weight:

[0008] 10-15 parts of modified SBS bitumen;

[0009] 60-70 parts coarse aggregate;

[0010] 20-30 parts fine aggregate;

[0011] 2-5 parts basalt fiber;

[0012] 1-3 parts steel fiber;

[0013] 3-7 parts of silicon-calcium composite filler;

[0014] 4-8 parts of limestone mineral powder;

[0015] 3-5 parts rubber powder;

[0016] 0.5-1.5 parts of silane coupling agent;

[0017] The modified SBS asphalt is obtained by modifying the base asphalt with SBS modifier and organic nano-montmorillonite.

[0018] By adopting the above technical solutions, this application lays the foundation for crack-resistant asphalt mixtures with both crack resistance and high-temperature stability through specific raw material compositions. In modified SBS asphalt, the SBS modifier imparts elasticity to improve low-temperature ductility, while organic nano-montmorillonite enhances the high-temperature stiffness modulus, resolving the contradiction of the base asphalt being brittle at low temperatures and soft at high temperatures. In the dual-fiber reinforcement system, basalt fibers inhibit the initiation of low-temperature shrinkage cracks, while steel fibers do not soften at high temperatures, constraining the lateral displacement of aggregates and preventing fiber failure at high temperatures that could lead to a loose skeleton. The silica-calcium composite filler improves the interfacial bonding between aggregates and asphalt, while rubber powder fills the gaps between aggregates and absorbs load impacts. The two work synergistically to enhance the density and elastic recovery capacity of the mixture, reducing permanent deformation at high temperatures and achieving a dual improvement in crack resistance and high-temperature stability.

[0019] In summary, the silica-calcium composite filler solves the problem of poor interfacial adhesion between the filler and asphalt by using polydopamine to enhance interfacial bonding and silane coupling agents to construct a dual interfacial bond, thereby enhancing structural stability at high temperatures. The modified SBS asphalt utilizes the synergistic effect of SBS modifiers and organic nano-montmorillonite to address the issues of high-temperature softness and low-temperature brittleness in the base asphalt, improving crack resistance and high-temperature stiffness. The dual-fiber system forms a three-dimensional interwoven skeleton, with basalt fibers resisting low-temperature shrinkage cracks and steel fibers constraining aggregate displacement at high temperatures. Together with polyethylene wax, it forms a "flexible crack-resistant + rigid deformation-resistant" reinforcement system, covering both low-temperature and high-temperature scenarios. Ultimately, the mixture in this application achieves a performance balance between crack resistance and high-temperature stability, improving the crack resistance and high-temperature stability of crack-resistant asphalt mixtures.

[0020] Optionally, the modified SBS asphalt is prepared by the following method:

[0021] (1) Heat the base asphalt to 160-170℃ and stir at a constant temperature until it is completely melted. Then add SBS modifier to the melted base asphalt and stir at 300-500r / min for 20-30min until the SBS modifier is completely dissolved to obtain intermediate mixture.

[0022] (2) Add organic nano-montmorillonite to the intermediate mixture, then ultrasonically disperse for 20-30 minutes. After ultrasonication, keep warm at 160-170℃ to obtain modified SBS asphalt.

[0023] Optionally, in step (1), the amount of SBS modifier added is 4%-6% of the mass of the base asphalt.

[0024] Optionally, in step (2), the amount of organic nano-montmorillonite added is 2%-4% of the mass of the matrix bitumen.

[0025] By employing the above technical solutions, the preparation method of modified SBS asphalt maximizes its synergistic performance of "high-temperature stability + low-temperature crack resistance". Precise control of the SBS modifier dosage ensures complete dissolution in the base asphalt, forming a continuous elastic network that effectively absorbs low-temperature shrinkage stress. Ultrasonic dispersion allows organic nano-montmorillonite to be uniformly intercalated between SBS molecular chains, enhancing the modified asphalt's high-temperature deformation resistance. Appropriate dosage also creates a rigid support threshold, preventing insufficient high-temperature stiffness or asphalt embrittlement. Strict temperature control prevents asphalt aging or incomplete SBS dissolution, ensuring the stability of the modified binder's performance.

[0026] Optionally, the silicon-calcium composite filler is prepared by the following method:

[0027] A. Mix calcium carbonate, metakaolin, and nano-silica to obtain a mixture; disperse the mixture in a polydopamine solution, adjust the pH to 8-9, stir and react at 60-70℃ for 2-3 hours, filter and dry to obtain the core material;

[0028] B. Add the core material to a γ-aminopropyltriethoxysilane solution, stir and react at 80-90℃ for 1-2 hours, and obtain the silicon-calcium composite filler after cooling.

[0029] Optionally, in step A, the mass ratio of calcium carbonate, metakaolin, and nano silica is (5-7):(2-4):1; the mass concentration of the polydopamine solution is 2%-5%, and the mass ratio of the mixture to the polydopamine solution is 1:(10-15).

[0030] Optionally, in step B, the mass concentration of the γ-aminopropyltriethoxysilane solution is 10%-15%, and the mass ratio of the core material to the γ-aminopropyltriethoxysilane solution is 100:(3-5).

[0031] By adopting the above technical solutions, the preparation of silicon-calcium composite fillers solves the defects of "poor adhesion at the filler-asphalt interface and easy loosening at high temperatures" and enhances high-temperature stability. The catechol groups of polydopamine solution form hydrogen bonds with the hydroxyl groups on the filler surface, and at the same time, they adsorb with the hydrocarbon groups of asphalt, improving the adhesion strength at the filler-asphalt interface. The fillers are compounded in a specific ratio to form a "rigid skeleton + micro-filler" structure, which enhances the high-temperature resistance to compression deformation of the mixture. The silane coupling agent constructs a dual interface bond of "hydrogen bonds + chemical bonds", which enables the fillers to remain stably attached to the aggregate surface at high temperatures, improving the overall structural resistance to deformation.

[0032] Optionally, the raw materials may also include 1-1.5 parts of polyethylene wax.

[0033] By adopting the above technical solution, the addition of polyethylene wax enhances the high-temperature rutting resistance without affecting the low-temperature crack resistance. The polyethylene wax melts and disperses at the asphalt mixing temperature, and upon cooling, forms solid polymer microparticles. At high temperatures, these particles are embedded in the aggregate gaps, inhibiting relative aggregate sliding; at low temperatures, they are compatible with the elastic network of SBS, without reducing the ductility of the mixture, thus solving the problem that traditional anti-rutting agents inevitably cause embrittlement upon hardening.

[0034] Optionally, the length of the basalt fiber and the steel fiber is 6-10 mm.

[0035] By adopting the above technical solution, the length of basalt fiber and steel fiber is controlled at 6-10mm, ensuring the maximum fiber reinforcement effect and avoiding agglomeration failure. This length allows the fiber to be evenly dispersed in the mixture, forming a synergistic system with aggregates and asphalt. At low temperatures, fiber tension inhibits crack propagation, and at high temperatures, fiber restrains aggregate displacement, thus doubly improving crack resistance and high-temperature stability.

[0036] Secondly, this application provides a method for preparing crack-resistant asphalt mixture, which adopts the following technical solution:

[0037] A method for preparing crack-resistant asphalt mixture includes the following steps:

[0038] Coarse aggregate, fine aggregate, calcium silicate composite filler, and limestone powder are added to a mixer and stirred at 180-190℃ for 1-3 minutes. Then, modified SBS asphalt and silane coupling agent are added and stirred at 160-170℃ for 3-5 minutes. Finally, basalt fiber, steel fiber, rubber powder, and optional polyethylene wax are added and stirred at 150-160℃ for 1-3 minutes to obtain crack-resistant asphalt mixture.

[0039] The above preparation method ensures that the performance of each component is fully utilized and avoids performance degradation caused by the process. The temperature and steps are precisely matched. First, coarse aggregate, calcium silicate filler and mineral powder are mixed to ensure that the filler uniformly coats the surface of the aggregate. Then, modified SBS asphalt is added to ensure its fluidity and prevent aging. Finally, fiber and rubber powder are added to prevent the fiber from softening at high temperature and the rubber powder from aging excessively. The stirring time is controlled to balance the dispersion uniformity and the risk of asphalt aging, ensuring that the final mixture is free of segregation and agglomeration and has stable performance.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. This application uses modified SBS asphalt to replace base asphalt. Through the synergistic effect of SBS modifier and organic nano-montmorillonite, the technical problems of high-temperature softening and low-temperature brittleness of base asphalt are solved, significantly improving the crack resistance and high-temperature stiffness of the mixture, achieving a balance between crack resistance and high-temperature stability. Traditional base asphalt is prone to softening at high temperatures, leading to permanent deformation diseases such as rutting on the road surface, while at low temperatures, it is prone to shrinkage cracks due to excessive brittleness. In the modified SBS asphalt of this application, the SBS modifier imparts good elasticity to the asphalt, improving its ductility under low-temperature conditions, effectively absorbing low-temperature shrinkage stress, and inhibiting the formation of cracks; the organic nano-montmorillonite enhances the high-temperature stiffness modulus of the asphalt, improving its resistance to deformation, making the asphalt less prone to softening and flowing at high temperatures. The synergistic effect of the two makes the modified SBS asphalt possess both low-temperature crack resistance and high-temperature stability, thus allowing the mixture to maintain good performance under different temperature conditions, meeting the multi-performance requirements of road engineering for asphalt mixtures, and greatly improving the service life and traffic quality of roads.

[0042] 2. This application preferably employs a dual-fiber reinforcement system composed of basalt fiber and steel fiber. Basalt fiber inhibits the initiation of low-temperature shrinkage cracks, while steel fiber does not soften at high temperatures and constrains the lateral displacement of aggregates, effectively avoiding the problem of fiber failure at high temperatures leading to a loose aggregate skeleton, and enhancing the mixture's resistance to permanent deformation under heavy traffic conditions. In low-temperature environments, pavement materials experience stress due to temperature shrinkage. Basalt fiber, with its excellent tensile properties, can create a tensile effect in the mixture, effectively inhibiting crack initiation and propagation, and improving the mixture's low-temperature crack resistance. In high-temperature environments, steel fiber, due to its high melting point and excellent mechanical properties, does not soften and fail like some organic fibers. It can form a tight bond with the aggregates, constraining their lateral displacement and preventing the aggregate skeleton from loosening. Under heavy traffic conditions, the repeated action of vehicle loads can generate significant stress in pavement materials, easily leading to permanent deformation of the mixture. The dual-fiber reinforcement system, through the advantages of each component under different temperature conditions, works together to enhance the overall mechanical properties of the mixture, enabling it to better withstand the long-term rolling of heavy vehicles, maintain the integrity of the pavement structure, and reduce the occurrence of defects such as rutting.

[0043] 3. The method of this application solves the technical problem of poor interfacial bonding between calcium silicate composite filler and asphalt by constructing a dual interfacial bond through polydopamine solution and silane coupling agent, thus enhancing the structural stability at high temperatures. Simultaneously, the use of rubber powder filling the aggregate gaps absorbs load impacts, synergistically enhancing the density and elastic recovery capacity of the mixture. In traditional asphalt mixtures, the interfacial bond between filler and asphalt is often insufficient. Under high-temperature conditions, this bond strength further decreases, leading to aggregate-asphalt separation and affecting the structural stability of the mixture. In this application, the catechol groups of the polydopamine solution can form hydrogen bonds with the hydroxyl groups on the filler surface and simultaneously adsorb onto the hydrocarbon groups of the asphalt, thereby improving the interfacial bond strength between the filler and asphalt. The silane coupling agent further constructs a dual interfacial bond of "hydrogen bonds + chemical bonds," enabling the filler to remain stably attached to the aggregate surface at high temperatures, greatly enhancing the high-temperature structural stability of the mixture. Furthermore, the rubber powder filling the aggregate gaps not only absorbs the impact energy generated by vehicle loads, reducing damage to the mixture, but also increases the elastic recovery capacity of the mixture. When the road surface deforms under vehicle load, the rubber powder can buffer the stress through its own elastic deformation and help the mixture return to its original shape after the load is removed, thereby effectively reducing the permanent deformation of the road surface and improving the road's durability and driving comfort. Detailed Implementation

[0044] The present application will be further described in detail below with reference to the embodiments.

[0045] Example of preparation of modified SBS bitumen

[0046] Preparation Example 1

[0047] Modified SBS bitumen was prepared using the following method:

[0048] (1) Take 100 kg of base asphalt, heat it to 160℃, and stir it at a constant temperature until it is completely melted; then add 4 kg of SBS modifier to the melted base asphalt, stir at 300 r / min for 20 min until the SBS modifier is completely dissolved to obtain intermediate mixture;

[0049] (2) Add 2 kg of organic nano-montmorillonite to the intermediate mixture, then ultrasonically disperse for 20 min. After ultrasonication, keep warm at 160℃ for 5 h to obtain modified SBS asphalt.

[0050] Preparation Example 2

[0051] Modified SBS bitumen was prepared using the following method:

[0052] (1) Take 100 kg of base asphalt, heat it to 165℃, and stir it at a constant temperature until it is completely melted; then add 5 kg of SBS modifier to the melted base asphalt, stir at 400 r / min for 25 min until the SBS modifier is completely dissolved to obtain intermediate mixture;

[0053] (2) Add 3 kg of organic nano-montmorillonite to the intermediate mixture, then ultrasonically disperse for 25 min. After ultrasonication, keep warm at 165℃ for 4 h to obtain modified SBS asphalt.

[0054] Preparation Example 3

[0055] Modified SBS bitumen was prepared using the following method:

[0056] (1) Take 100 kg of base asphalt, heat it to 170°C, and stir it at a constant temperature until it is completely melted; then add 6 kg of SBS modifier to the melted base asphalt, stir at 500 r / min for 30 min until the SBS modifier is completely dissolved to obtain intermediate mixture;

[0057] (2) Add 4 kg of organic nano-montmorillonite to the intermediate mixture, then ultrasonically disperse for 30 min. After ultrasonication, keep warm at 170℃ for 5 h to obtain modified SBS asphalt.

[0058] Preparation Example 4

[0059] Modified SBR asphalt was prepared using the following method:

[0060] Take 100 kg of base asphalt, heat it to 160℃, and stir it at a constant temperature until it is completely melted; add 5 kg of SBR modifier to the melted base asphalt, stir at 400 r / min for 30 min until the SBR modifier is completely dissolved; keep it at 160℃ for 5 h to obtain modified SBR asphalt.

[0061] Example of preparation of silicon-calcium composite filler

[0062] Preparation Example 5

[0063] The silicon-calcium composite filler was prepared using the following method:

[0064] A. Weigh 5 kg of calcium carbonate, 2 kg of metakaolin, and 1 kg of nano-silica at a mass ratio of 5:2:1, and mix them evenly to obtain a mixture. Disperse the mixture in a 2% polydopamine solution at a mass ratio of 1:10. Adjust the pH to 8, stir and react at 60°C for 2 hours, filter, and dry to obtain the core material.

[0065] B. The core material is added to a 10% (w / w) γ-aminopropyltriethoxysilane solution with a mass ratio of 100:3. The mixture is stirred at 80°C for 1 hour and then cooled to obtain a silicon-calcium composite filler.

[0066] Preparation Example 6

[0067] The silicon-calcium composite filler was prepared using the following method:

[0068] A. Weigh 6 kg of calcium carbonate, 3 kg of metakaolin, and 1 kg of nano-silica at a mass ratio of 6:3:1, and mix them evenly to obtain a mixture. Disperse the mixture in a 3% polydopamine solution at a mass ratio of 1:12, adjust the pH to 8.5, stir and react at 65℃ for 2.5 h, filter and dry to obtain the core material.

[0069] B. The core material was added to a 12% (w / w) γ-aminopropyltriethoxysilane solution with a mass ratio of 100:4. The mixture was stirred at 85°C for 1.5 h and then cooled to obtain a silicon-calcium composite filler.

[0070] Preparation Example 7

[0071] The silicon-calcium composite filler was prepared using the following method:

[0072] A. Weigh 7 kg of calcium carbonate, 4 kg of metakaolin, and 1 kg of nano-silica according to a mass ratio of 7:4:1, and mix them evenly to obtain a mixture. Disperse the mixture in a 5% polydopamine solution with a mass ratio of 1:15. Adjust the pH to 9, stir and react at 70°C for 3 hours, filter, and dry to obtain the core material.

[0073] B. The core material was added to a 15% (w / w) γ-aminopropyltriethoxysilane solution with a mass ratio of 100:5. The mixture was stirred at 90°C for 2 hours and then cooled to obtain a silicon-calcium composite filler.

[0074] Preparation Example 8

[0075] The calcium carbonate filler differs from that in Preparation Example 7 in that no nano-silica was added in this preparation example.

[0076] Example

[0077] Example 1

[0078] A crack-resistant asphalt mixture, the raw material composition and dosage of which are shown in Table 1, wherein the modified SBS asphalt is the modified SBS asphalt prepared in Preparation Example 1, the coarse aggregate is diabase aggregate with a particle size range of 5-20 mm, a crushing value ≤12%, and a moisture content ≤0.3%; the fine aggregate is granite fine aggregate with a particle size range of 0.075-5 mm, an angularity ≥45s, and a mud content ≤3%; the length of the basalt fiber and steel fiber is 6 mm; the silicon-calcium composite filler is the silicon-calcium composite filler prepared in Preparation Example 5; and the silane coupling agent is KH-570.

[0079] A crack-resistant asphalt mixture is prepared by the following method:

[0080] Coarse aggregate, fine aggregate, calcium silicate composite filler, and limestone powder are added to a mixer and stirred at 180°C for 1 minute. Then, modified SBS asphalt and silane coupling agent are added and stirred at 160°C for 3 minutes. Finally, basalt fiber, steel fiber, and rubber powder are added and stirred at 150°C for 1 minute to obtain crack-resistant asphalt mixture.

[0081] Example 2

[0082] A crack-resistant asphalt mixture, the raw material composition and dosage of which are shown in Table 1, wherein the modified SBS asphalt is the modified SBS asphalt prepared in Preparation Example 2, the coarse aggregate is diabase aggregate with a particle size range of 5-20 mm, a crushing value ≤12%, and a moisture content ≤0.3%; the fine aggregate is granite fine aggregate with a particle size range of 0.075-5 mm, an angularity ≥45s, and a mud content ≤3%; the length of the basalt fiber and steel fiber is 8 mm; the silicon-calcium composite filler is the silicon-calcium composite filler prepared in Preparation Example 6; and the silane coupling agent is KH-570.

[0083] A crack-resistant asphalt mixture is prepared by the following method:

[0084] Coarse aggregate, fine aggregate, calcium silicate composite filler, and limestone powder are added to a mixer and stirred at 185°C for 2 minutes. Then, modified SBS asphalt and silane coupling agent are added and stirred at 165°C for 4 minutes. Finally, basalt fiber, steel fiber, and rubber powder are added and stirred at 155°C for 2 minutes to obtain crack-resistant asphalt mixture.

[0085] Example 3

[0086] A crack-resistant asphalt mixture, the raw material composition and dosage of which are shown in Table 1, wherein the modified SBS asphalt is the modified SBS asphalt prepared in Preparation Example 3, the coarse aggregate is diabase aggregate with a particle size range of 5-20 mm, a crushing value ≤12%, and a moisture content ≤0.3%; the fine aggregate is granite fine aggregate with a particle size range of 0.075-5 mm, an angularity ≥45s, and a mud content ≤3%; the length of the basalt fiber and steel fiber is 10 mm; the silicon-calcium composite filler is the silicon-calcium composite filler prepared in Preparation Example 7; and the silane coupling agent is KH-570.

[0087] A crack-resistant asphalt mixture is prepared by the following method:

[0088] Coarse aggregate, fine aggregate, calcium silicate composite filler and limestone powder are added to a mixer and stirred at 190°C for 3 minutes. Then, modified SBS asphalt and silane coupling agent are added and stirred at 170°C for 5 minutes. Finally, basalt fiber, steel fiber and rubber powder are added and stirred at 160°C for 3 minutes to obtain crack-resistant asphalt mixture.

[0089] Table 1. Raw material components and dosage (kg) of asphalt mixtures in Examples 1-3

[0090]

[0091] Example 4

[0092] A crack-resistant asphalt mixture differs from Example 3 in that: 1 kg of polyethylene wax is added to the raw materials in this example; the subsequent steps are the same as in Example 3, and polyethylene wax is added at the same time as basalt fiber, steel fiber, and rubber powder in the last step to obtain the crack-resistant asphalt mixture.

[0093] Example 5

[0094] A crack-resistant asphalt mixture differs from Example 3 in that: 1.2 kg of polyethylene wax is added to the raw materials in this example; the subsequent steps are the same as in Example 3, and polyethylene wax is added at the same time as basalt fiber, steel fiber, and rubber powder in the last step to obtain the crack-resistant asphalt mixture.

[0095] Example 6

[0096] A crack-resistant asphalt mixture differs from Example 3 in that: 1.5 kg of polyethylene wax is added to the raw materials in this example; the subsequent steps are the same as in Example 3, and polyethylene wax is added at the same time as basalt fiber, steel fiber, and rubber powder in the last step to obtain the crack-resistant asphalt mixture.

[0097] Comparative Example

[0098] Comparative Example 1

[0099] A crack-resistant asphalt mixture, which differs from Example 6 in that an equal amount of base asphalt is used instead of modified SBS asphalt in this comparative example.

[0100] Comparative Example 2

[0101] A crack-resistant asphalt mixture, which differs from Example 6 in that steel fibers are not added in this comparative example, and fine aggregate is used instead.

[0102] Comparative Example 3

[0103] A crack-resistant asphalt mixture, which differs from Example 6 in that the modified SBR asphalt prepared in Preparation Example 4 is used instead of the modified SBS asphalt in this comparative example.

[0104] Comparative Example 4

[0105] A crack-resistant asphalt mixture, which differs from Example 6 in that the calcium carbonate filler prepared in Preparation Example 8 is used instead of the calcium silicate composite filler in this comparative example.

[0106] Comparative Example 5

[0107] A crack-resistant asphalt mixture, which differs from Example 6 in that no rubber powder is added in this comparative example.

[0108] Performance testing

[0109] Performance tests were conducted on the asphalt mixtures prepared in Examples 1-6 and Comparative Examples 1-5, and the results are shown in Table 2.

[0110] Table 2 Experimental Results

[0111]

[0112] As shown in Table 2, the crack-resistant asphalt mixtures prepared in Examples 1-3 exhibited excellent properties in various performance indicators. Regarding high-temperature resistance, the dynamic stability at 60℃ was 12500 cycles / mm for Example 1, 12600 cycles / mm for Example 2, and 12700 cycles / mm for Example 3. This indicates that with the optimization of the modified SBS asphalt content and the proportions of each raw material, the mixture's ability to resist rutting deformation at high temperatures gradually increased, enabling it to better adapt to high-temperature environments and reduce rutting damage caused by heavy loads and high temperatures. In terms of crack resistance, the bending strain data at -10℃ showed 4300 με for Example 1, 4200 με for Example 2, and 4500 με for Example 3. This indicates that the mixture has good toughness in low-temperature environments, effectively resisting stress caused by temperature shrinkage and inhibiting the generation and propagation of cracks. Regarding water stability and freeze-thaw splitting strength ratio, Example 1 showed 91.5%, Example 2 showed 92.4%, and Example 3 showed 93.7%, reflecting the strong anti-stripping ability of the mixture under moisture conditions, good interfacial adhesion, and the ability to ensure the long-term performance of the road in humid environments. Overall, Examples 1-3 achieved a synergistic improvement in high-temperature resistance, crack resistance, and water stability through reasonable raw material ratios and preparation processes.

[0113] Examples 4-6, based on Example 3, added polyethylene wax to further optimize the performance of the mixture. Regarding high-temperature resistance, the dynamic stability data at 60℃ showed that Example 4 achieved 13200 cycles / mm, Example 5 reached 13400 cycles / mm, and Example 6 achieved 13500 cycles / mm, representing a significant improvement compared to Examples 1-3. This is attributed to the polyethylene wax forming solid polymer microparticles at high temperatures, which are embedded in the aggregate gaps, effectively suppressing relative slippage of the aggregates and enhancing the mixture's high-temperature rutting resistance. In terms of crack resistance, the bending strain at -10℃ showed that Example 4 was 4700 με, Example 5 was 4800 με, and Example 6 reached 4950 με, indicating that the addition of polyethylene wax did not affect the low-temperature ductility of the mixture; on the contrary, it was compatible with the elastic network of SBS, further improving the mixture's crack resistance at low temperatures. Regarding water stability, the freeze-thaw splitting strength ratio data showed that Example 4 had a ratio of 95.6%, Example 5 had a ratio of 96.2%, and Example 6 had a ratio of 96.7%, indicating that the addition of polyethylene wax also helps to improve the water stability of the mixture, enhances the interfacial adhesion between the filler and the asphalt, and reduces the spalling problem caused by moisture intrusion. Therefore, it is evident that the addition of polyethylene wax further improves the mixture's high-temperature resistance, crack resistance, and water stability.

[0114] Comparative Example 1 used an equal amount of base asphalt instead of modified SBS asphalt, and the performance difference compared to Example 6 was significant. Regarding high-temperature resistance, the dynamic stability at 60℃ was only 4700 cycles / mm, far lower than the 13500 cycles / mm of Example 6, indicating that the base asphalt has weak high-temperature deformation resistance and cannot effectively resist rutting at high temperatures. In terms of crack resistance, the flexural strain at -10℃ was 3830 με, lower than the 4950 με of Example 6, indicating that the base asphalt is brittle at low temperatures and prone to shrinkage cracks. Regarding water stability, the freeze-thaw splitting strength ratio was 82.4%, also significantly lower than the 96.7% of Example 6, reflecting poor interfacial bonding between the base asphalt and the filler, making it prone to spalling under moisture. This fully demonstrates that using modified SBS asphalt is crucial for improving the high-temperature resistance, crack resistance, and water stability of the mixture.

[0115] Comparative Example 2, without added steel fibers, showed significant performance changes compared to Example 6. Regarding high-temperature resistance, the dynamic stability at 60℃ was 11340 cycles / mm, lower than Example 6's 13500 cycles / mm, indicating that steel fibers play a crucial role in restraining lateral aggregate displacement and enhancing the mixture's resistance to rutting at high temperatures; the absence of steel fibers leads to a decrease in the mixture's high-temperature stability. In terms of crack resistance, the bending strain at -10℃ was only 2500 με, far lower than Example 6's 4950 με, indicating that the dual-fiber system composed of steel fibers and basalt fibers has a synergistic effect in inhibiting crack propagation; the absence of steel fibers alone severely weakens the mixture's low-temperature crack resistance. Regarding water stability, the freeze-thaw splitting strength ratio was 72.6%, also lower than Example 6's 96.7%, suggesting that the absence of steel fibers may affect the overall structural stability of the mixture, making it more prone to spalling under moisture. This demonstrates the importance of the dual-fiber system in improving the overall performance of the mixture.

[0116] Comparative Example 3 used modified SBR asphalt instead of modified SBS asphalt, and its performance decreased compared to Example 6. Regarding high-temperature resistance, the dynamic stability at 60℃ was 8700 cycles / mm, lower than the 13500 cycles / mm of Example 6, indicating that modified SBS asphalt is superior to modified SBR asphalt in improving the high-temperature stability of the mixture. In terms of crack resistance, the flexural strain at -10℃ was 3950 με, lower than the 4950 με of Example 6, indicating that modified SBS asphalt also has an advantage in low-temperature crack resistance. Regarding water stability, the freeze-thaw splitting strength ratio was 86.2%, lower than the 96.7% of Example 6, reflecting better interfacial bonding between the modified SBS asphalt and the filler, as well as better overall structural stability.

[0117] Comparative Example 4 used calcium carbonate filler instead of calcium silicate composite filler, and its performance deteriorated compared to Example 6. Regarding high-temperature resistance, the dynamic stability at 60℃ was 10300 cycles / mm, lower than the 13500 cycles / mm of Example 6, indicating that the calcium silicate composite filler is superior to calcium carbonate filler in improving the high-temperature deformation resistance of the mixture. In terms of crack resistance, the flexural strain at -10℃ was 4050 με, lower than the 4950 με of Example 6, indicating that the calcium silicate composite filler also has a positive impact on the low-temperature crack resistance of the mixture. Regarding water stability, the freeze-thaw splitting strength ratio was 88.6%, lower than the 96.7% of Example 6, indicating that the dual interfacial bonding constructed by the calcium silicate composite filler and the polydopamine and silane coupling agent enhances the interfacial adhesion between the filler and the asphalt, thus improving the water stability of the mixture.

[0118] Comparative Example 5, without added rubber powder, showed altered properties compared to Example 6. Regarding high-temperature resistance, the dynamic stability at 60℃ was 13300 cycles / mm, similar to Example 6, indicating that the rubber powder had a relatively small impact on the mixture's high-temperature rutting resistance. In terms of crack resistance, the flexural strain at -10℃ was only 3150 με, significantly lower than the 4950 με of Example 6, indicating that the rubber powder plays a crucial role in filling aggregate gaps, absorbing load impacts, and enhancing the mixture's low-temperature crack resistance. Regarding water stability, the freeze-thaw splitting strength ratio was 79.8%, lower than the 96.7% of Example 6, suggesting that the absence of rubber powder may have affected the overall density and elastic recovery of the mixture, making it more prone to spalling under moisture.

[0119] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A crack resistant asphalt mixture characterized in that, Comprise the following raw materials by weight parts: Modified SBS asphalt 10-15 parts; Coarse aggregate 60-70 parts; Fine aggregate 20-30 parts; Basalt fiber 2-5 parts; Steel fiber 1-3 parts; Silicon-calcium composite filler 3-7 parts; Limestone powder 4-8 parts; Rubber powder 3-5 parts; Silane coupling agent 0.5-1.5 parts; The modified SBS asphalt is obtained by modifying the base asphalt with SBS modifier and organic nano montmorillonite; The silicon-calcium composite filler is prepared by the following method: A, mixing calcium carbonate, metakaolin and nano silicon dioxide to obtain a mixture, the mass ratio of calcium carbonate, metakaolin and nano silicon dioxide is (5-7):(2-4):1; dispersing the mixture in a polydopamine solution, adjusting the pH to 8-9, stirring and reacting at 60-70℃ for 2-3h, filtering and drying to obtain a core material; B, adding the core material into a γ-aminopropyl triethoxysilane solution, stirring and reacting at 80-90℃ for 1-2h, and cooling to obtain the silicon-calcium composite filler.

2. The anti-cracking asphalt mixture according to claim 1, characterized in that, The modified SBS asphalt is prepared by the following method: (1) heating the base asphalt to 160-170℃, constant temperature stirring until completely melted, then adding SBS modifier into the molten base asphalt, stirring at 300-500r / min for 20-30min until the SBS modifier is completely dissolved, to obtain an intermediate mixture; (2) adding organic nano montmorillonite into the intermediate mixture, then ultrasonic dispersion for 20-30min, and keeping warm for 3-5h after ultrasonic dispersion, to obtain the modified SBS asphalt.

3. The anti-cracking asphalt mixture according to claim 2, characterized in that: In step (1), the addition amount of the SBS modifier is 4%-6% of the mass of the base asphalt.

4. The anti-cracking asphalt mixture of claim 2, wherein: In step (2), the addition amount of the organic nano montmorillonite is 2%-4% of the mass of the base asphalt.

5. The anti-cracking asphalt mixture of claim 1, wherein: In step A, the mass concentration of the polydopamine solution is 2%-5%, and the mass ratio of the mixture to the polydopamine solution is 1:(10-15).

6. The anti-cracking asphalt mixture of claim 1, wherein: In step B, the mass concentration of the γ-aminopropyl triethoxysilane solution is 10%-15%, and the mass ratio of the core material to the γ-aminopropyl triethoxysilane solution is 100:(3-5).

7. The anti-cracking asphalt mixture of claim 1, wherein: The raw materials further comprise 1-1.5 parts of polyethylene wax.

8. The anti-cracking asphalt mixture of claim 1, wherein: The length of the basalt fiber and the steel fiber is 6-10mm.

9. A method of producing a crack-resistant asphalt mixture according to any one of claims 1-8, characterized in that, Comprise the following steps: Adding the coarse aggregate, fine aggregate, silicon-calcium composite filler and limestone powder into a mixer, stirring at 180-190℃ for 1-3min, then adding the modified SBS asphalt and silane coupling agent, continuing to stir at 160-170℃ for 3-5min, finally adding the basalt fiber, steel fiber, rubber powder and optional polyethylene wax, stirring at 150-160℃ for 1-3min, to obtain the anti-cracking asphalt mixture.

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