Stable and durable high-content waste tire rubber powder modified asphalt, mixture and preparation method

Abstract

This invention relates to a stable and durable high-content waste tire rubber powder modified asphalt, its mixture, and a preparation method. The raw materials, by weight percentage, are: 100 parts base asphalt; 40-50 parts waste tire rubber powder; 5-7 parts viscosity reducer; 0.1-0.8 parts crosslinking agent; and 1-2 parts reinforcing agent. The crosslinking agent is ABS, and the viscosity reducer is at least one selected from naphthenic rubber oil, alkane rubber oil, aromatic rubber oil, and polycyclic aromatic rubber oil. In the mixture, 40-mesh and 200-mesh waste tire rubber powder are added. The combination of rubber powder with different particle sizes replaces aggregate and filler in equal amounts, and forms a combination with some incompletely swollen rubber powder in the modified asphalt, achieving stable gradation. This high-content waste tire rubber powder modified asphalt not only significantly increases the waste tire rubber powder content but also exhibits good product stability and can be stored for a longer period. The stability and durability of its modified asphalt mixture are significantly improved, further enhancing the road performance of rubber asphalt and extending the service life of the pavement.

Description

Technical Field

[0001] This invention belongs to the field of modified asphalt technology, specifically a stable and durable high-content waste tire rubber powder modified asphalt, mixture, and preparation method. Background Technology

[0002] Waste tire rubber powder modified asphalt is a binder formed by mixing and swelling a certain proportion of waste tire rubber powder with base asphalt. It not only effectively solves the environmental pollution problem caused by waste tire stockpiling but also possesses excellent road performance. The high-temperature stability, rutting resistance, and fatigue resistance of waste tire rubber powder modified asphalt mixtures are equal to or slightly better than SBS modified asphalt, but it is more environmentally friendly and has a lower cost, attracting increasing attention from all sectors. Therefore, it has been extensively researched and promoted both domestically and internationally, and is commonly used in surface layers and interlayer bonding, waterproofing, stress absorption, and other functional layers of road structures. However, on the one hand, the rubber powder content in rubber asphalt is usually controlled at around 20%. This is because a higher rubber powder content leads to a greater increase in the viscosity of the modified asphalt, which is detrimental to the mixing, paving, and compaction processes of the rubber asphalt mixture, limiting the increase and development of the amount of rubber powder in asphalt. On the other hand, existing rubber asphalt applications, whether factory-produced or prepared on-site, have a short shelf life and are prone to segregation, affecting the performance of the rubber asphalt and hindering the productization, industrialization, and large-scale development of rubber asphalt.

[0003] Li Shuren of Southeast University studied the noise reduction performance of high-rubber-modified asphalt mixtures. While ensuring the workability of rubber asphalt, he achieved a target of 35% rubber powder content, but further increases in content were limited. Sun Yuhao of Hebei University of Technology achieved mixtures with 35% and 50% rubber powder content by introducing rubber powder, base asphalt, desulfurizer, and softener. He obtained the fatigue equation and curve of the 35% rubber-modified asphalt mixture through four-point bending fatigue tests, but the processing temperature required was around 230℃. A method of achieving high content by chemically activating and pretreating rubber powder was adopted, which involved desulfurization pretreatment of the rubber powder. This process was not only cumbersome and polluting, but also resulted in high raw material processing costs. The preparation method involved high production temperatures and long processing times, and the asphalt performance needed to be improved.

[0004] In addition, existing studies have shown that high-content waste tire rubber powder modified asphalt has poor storage stability and cannot be stored for a long time, which hinders the development of high-content waste tire rubber powder modified asphalt. Summary of the Invention

[0005] The purpose of this invention is to provide a stable and durable high-content waste tire rubber powder modified asphalt, mixture, and preparation method. This high-content waste tire rubber powder modified asphalt not only significantly increases the waste tire rubber powder content, but also has good product stability and can be stored for a longer period of time. The stability and durability of its modified asphalt mixture are significantly improved, which can further improve the road performance of rubber asphalt and extend the service life of the pavement.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A stable and durable modified asphalt with high content of waste tire rubber powder, the raw materials by weight percentage are: 100 parts base asphalt; 40-50 parts waste tire rubber powder; 5-7 parts viscosity reducer; 0.1-0.8 parts crosslinking agent; 1-2 parts reinforcing agent; The crosslinking agent is ABS, and the viscosity reducer is at least one of cycloalkyl rubber oil, alkane rubber oil, aromatic rubber oil, and polycyclic aromatic rubber oil.

[0007] Furthermore, the particle size of the waste tire rubber powder is 40-100 mesh, preferably 60-80 mesh. More preferably, the particle size of the waste tire rubber powder is 60 mesh.

[0008] The reinforcing agent is selected from at least one of low-grade hard asphalt, ethylene-vinyl acetate plastic granules (EVA granules), polypropylene (PP) granules, and styrene-butadiene-styrene block copolymer (SBS) granules; the base asphalt is 70# or 90# road petroleum asphalt.

[0009] The preparation method of the above modified asphalt is as follows: (1) Place the container containing the base bitumen in a heating jacket and heat it until the temperature is stable at 130-150℃; (2) Stir continuously at a speed of 1000-1500 rpm, add viscosity reducer, maintain temperature and speed, and stir for 10-20 minutes; (3) Increase the temperature to 180-200℃, add waste tire rubber powder in 6-8 batches, and shear after each addition of waste tire rubber powder. Set the shearing speed to 3000-5000 rpm. (4) Add reinforcing agent, increase shearing speed to 6500-7500 rpm, and maintain high-speed shearing for 25-35 min at the temperature; (5) Add crosslinking agent and stir for 8-12 min, then shear again at a shear speed of 6500-7500 rpm for 15-25 min; (6) Then place it in a constant temperature chamber at 180-190℃ for 30-40 minutes to develop, and obtain stable and durable high-content waste tire rubber powder modified asphalt.

[0010] Preferably, in step (3), the waste tire rubber powder is added in 6-8 batches, with a time interval of 1-3 minutes between each addition, and the mixture is continuously stirred with a glass rod during the preparation process to ensure that the waste tire rubber powder is evenly distributed and fully swollen.

[0011] Furthermore, the segregation softening point difference of the modified asphalt is controlled within 1.0℃, and the softening point is greater than 85℃. Preferably, the softening point is greater than 90℃, while also taking into account the requirements for ductility and mass loss at 5℃.

[0012] This invention also protects a stable and durable high-content waste tire rubber powder modified asphalt mixture, comprising the following components by weight percentage: 100 parts aggregate; 4-6 parts modified asphalt; 3-5 parts waste tire rubber powder; 60-mesh rubber powder is added during the asphalt modification process for swelling modification. In the mixture preparation process, 40-mesh rubber powder replaces the same gradation of aggregate in the mineral materials, and 200-mesh rubber powder replaces part of the mineral powder.

[0013] The preparation method of the above-mentioned stable and durable high-content waste tire rubber powder modified asphalt mixture, the process of the preparation method is as follows: (1) Place the aggregate and waste tire rubber powder together in an oven at 105℃±5℃ and dry them until constant weight. The heating time shall not be less than 4-6 hours. Use 40-mesh rubber powder to replace the stone of the same grade in the mineral material, and use 200-mesh rubber powder to replace part of the mineral powder. (2) Weigh the dried and graded coarse and fine aggregates according to the design gradation requirements of each specimen, mix them evenly in a metal pan, and store the mineral powder separately. (3) After mixing the coarse and fine aggregates according to the proportion, pour them into the mixer and stir evenly. Keep the temperature at 180℃±5℃, add waste tire rubber powder with a particle size of 40 mesh, and continue stirring for 1~2 minutes. (4) Add the modified asphalt and stir for 2-4 minutes; (5) Add mineral powder and waste tire rubber powder with a particle size of 200 mesh, stir for 1~2 minutes to obtain stable and durable high-content waste tire rubber powder modified asphalt mixture.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The modified asphalt of this invention uses ordinary waste tire rubber powder without adding sulfur-based stabilizers or using activated rubber powder, and can achieve an admixture content of over 40% (40% to 50%). In the formulation system, the crosslinking agent ABS promotes the miscibility of rubber powder and asphalt, and works synergistically with the viscosity reducer to achieve homogeneous dissolution and realize the stable incorporation of high-content rubber powder.

[0015] In this invention, 40-mesh and 200-mesh rubber powders are added to the mixture. The rubber powders of different particle sizes are combined and added by dry method. Then, the aggregate and filler are replaced in equal amounts, and they are combined with some of the incompletely swollen rubber powders in the modified asphalt to achieve stable gradation.

[0016] In the preparation method of stable and durable high-content waste tire rubber powder modified asphalt mixture of the present invention, the waste tire rubber powder is graded and combined in multiple particle sizes to maximize the recycling efficiency of waste tire rubber powder. In the embodiment, 60-mesh rubber powder is added in the process of modifying asphalt with high-content waste tire rubber powder for swelling modification to achieve high-content process at the asphalt binder level. Then, in the preparation process of the mixture, 40-mesh rubber powder is used to replace the same grade of stone in the aggregate, and 200-mesh rubber powder is used to replace part of the mineral powder. High content is achieved from the perspective of aggregate (stone) and filler. The combination of the three achieves a comprehensive high-content process.

[0017] This invention systematically combines three aspects: asphalt binder (modified asphalt), mineral aggregates in the mixture, and fillers, to form a new ultra-high rubber powder content process. This high-content process achieves excellent stability of modified asphalt without the use of stabilizers such as sulfur, saving materials. Furthermore, it directly uses pulverized waste tire rubber powder, eliminating the need for secondary activation treatment. The process is convenient, cost-effective, and represents a green, low-carbon, energy-saving, and emission-reducing new formula and process.

[0018] This invention relates to stable and durable high-content waste tire rubber powder modified asphalt and its mixture, which has excellent storage stability and high and low temperature stability, enabling stable storage and high product durability. The road surface paved with its mixture can resist rutting and cracking, thus extending the service life of the road. Detailed Implementation

[0019] To facilitate understanding of the present invention, various exemplary embodiments of the present invention are now described in detail. This detailed description should not be regarded as a specific limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0020] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising" shall be understood to include the stated components without excluding other components.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0022] The test methods and standards used in the following examples are based on the Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering (JTG E20-2011).

[0023] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0024] This invention relates to a stable and durable high-content waste tire rubber powder modified asphalt, characterized in that the raw materials, by weight percentage, are: 100 parts base asphalt; 40-50 parts waste tire rubber powder; 5-7 parts viscosity reducer; 0.1-0.8 parts crosslinking agent; and 1-2 parts reinforcing agent. The crosslinking agent is ABS, and the viscosity reducer is at least one selected from naphthenic rubber oil, alkane rubber oil, aromatic rubber oil, and polycyclic aromatic rubber oil. Preferably, the naphthenic rubber oil is naphthenic rubber oil KN4010.

[0025] This invention relates to a stable and durable high-content waste tire rubber powder modified asphalt mixture, comprising the following components by weight percentage: 100 parts aggregate; 4-6 parts modified asphalt; and 3-5 parts waste tire rubber powder. The modified asphalt is a stable and durable high-content waste tire rubber powder modified asphalt. 40-mesh rubber powder replaces the same gradation of aggregate in the mineral materials, and 200-mesh rubber powder replaces part of the mineral powder; high content is achieved from the perspective of both mineral materials and fillers.

[0026] Furthermore, the particle size of the waste tire rubber powder is 40-100 mesh.

[0027] The reinforcing agent is selected from at least one of low-grade hard asphalt, ethylene-vinyl acetate plastic granules (EVA granules), polypropylene (PP granules), styrene-butadiene-styrene block copolymer (SBS) granules, etc.; the base asphalt is 70# or 90# road petroleum asphalt, etc.

[0028] Example 1 The stable and durable high-content waste tire rubber powder modified asphalt of this embodiment includes the following components by weight percentage: 100 parts base asphalt; 40 parts waste tire rubber powder; 6 parts viscosity reducer; 0.5 parts crosslinking agent; and 2 parts reinforcing agent.

[0029] Waste tire rubber powder is untreated waste tire rubber powder with a particle size of 60 mesh. The viscosity reducer is naphthenic rubber oil, the crosslinking agent is ABS, and the reinforcing agent is SBS. The base asphalt is 70# road petroleum asphalt.

[0030] The performance parameters of the naphthenic rubber oil viscosity reducer described in this embodiment can be:

[0031] The preparation method of the above-mentioned stable and durable high-content waste tire rubber powder modified asphalt is as follows: (1) Place the container containing the base bitumen in a heating jacket and heat it until the temperature is stable at 140℃; (2) Stir the asphalt at a speed of 1200 rpm, add a viscosity reducer, maintain the temperature and speed, and stir for 15 minutes; (3) Increase the asphalt temperature to 185℃ and add waste tire rubber powder in 7 batches; (4) The asphalt was subjected to high-speed shearing, with the shearing speed set to 4000 rpm; (5) Add reinforcing agent and increase shear speed to 7000 rpm; (6) Maintain the temperature and shear at high speed for 30 minutes. After shearing, add crosslinking agent and stir for 10 minutes. Perform a second shearing for 20 minutes. (7) The modified asphalt was placed in a constant temperature chamber at 185℃ for 30 minutes to develop, and a stable and durable high-content waste tire rubber powder modified asphalt was obtained.

[0032] Examples 2-4 The raw materials and preparation methods in this embodiment are the same as in Example 1. The difference is that different types of viscosity reducers are used in this embodiment to replace the cycloalkyl rubber oil in Example 1. Alkane rubber oil, aromatic rubber oil and polycyclic aromatic rubber oil are selected respectively.

[0033]

[0034] In this invention, naphthenic rubber oil is selected as the optimal viscosity reducer, which can fully synergize with ABS, significantly improving low-temperature performance while maintaining good high-temperature performance. Simultaneously, it meets the requirements of a softening point temperature above 90℃, an elongation of over 20cm at 5℃, and mass loss controlled within 0.25%. The softening point temperature of different viscosity reducers can all be controlled above 85℃.

[0035] Examples 5-7 This embodiment modifies the particle size of the waste tire rubber powder in Example 1 to 40 mesh, 80 mesh, and 100 mesh, while maintaining the same formulation ratios and preparation methods as in Example 1. Specific experimental test results are shown in the table below:

[0036] As can be seen from the table above, the softening point of the formula in this application is above 85℃ under different particle sizes of waste tire rubber powder. The mass loss after TFOT aging is controlled within 0.25%, and the durability residual ductility ratio is maintained above 80%. In particular, when the particle size of waste tire rubber powder is selected as 60 mesh, the modified asphalt product has the best performance, with a ductility of more than 20 cm at 5℃, the best anti-aging effect, and a durability residual ductility ratio maintained above 88%, resulting in the best asphalt durability and enabling long-term preservation.

[0037] Comparative Example Comparative Example 1 was prepared without crosslinking agent, based on Example 1. The waste tire rubber powder had a particle size of 60 mesh, and the base asphalt consisted of 100 parts; waste tire rubber powder 40 parts; reinforcing agent 2 parts; and crosslinking agent 0 parts. In Comparative Examples 2-4, the crosslinking agents were ASA, PC / ABS, and PP, respectively, at a dosage of 0.5 parts each. The remaining formulation ratios and preparation methods were the same as in Example 1. The test results are shown in the table below:

[0038] The formulation of this invention maintains a low segregation softening point difference of around 0.8°C without the addition of additional stabilizers, achieving a small segregation softening point difference at a relatively high softening point temperature (around 100°C) while maintaining effective durability.

[0039] The addition of crosslinking agent ABS can further improve the storage stability of high rubber content powder. Using the difference in segregation softening point as an indicator, it can be seen that the reduction in Example 1 is 71% (the difference in segregation softening point in Comparative Example 1 is 2.8, which is reduced to 0.8 after the addition of crosslinking agent, and the reduction accounts for 2 / 2.8=71%). The effect of ABS crosslinking agent on promoting melting and crosslinking of asphalt, naphthenic rubber oil and rubber powder is very obvious. The synergistic effect of these factors achieves the effect of excellent stable storage.

[0040] Example 8 This embodiment utilizes the stable and durable high-content waste tire rubber powder modified asphalt from Example 1 to prepare a mixture. The mixture includes the following components by weight percentage: 100 parts aggregate; 5 parts modified asphalt; and 4 parts waste tire rubber powder.

[0041] In the process of modifying asphalt with high-dosage waste tire rubber powder, 60-mesh rubber powder is added for swelling modification to achieve high-dosage process at the asphalt binder level. Then, in the preparation of the mixture, 40-mesh rubber powder is used to replace the same grade of stone in the aggregate, and 200-mesh rubber powder is used to replace part of the mineral powder. High dosing is achieved from the perspective of aggregate and filler. The combination of the three achieves a comprehensive high-dosing process.

[0042] The pass rate of the original aggregate gradation in this embodiment is shown in the table below.

[0043] In this invention, 40-mesh and 200-mesh adhesive powders respectively replace the 0.3mm stone and some mineral powders smaller than 0.075mm in the table above.

[0044] The specific preparation process of the mixture is as follows: (1) Place the aggregate and waste tire rubber powder together in an oven at 105℃±5℃ and dry them until constant weight. The heating time shall not be less than 4-6 hours. Use 40-mesh rubber powder to replace the stone material (which belongs to aggregate) of the same grade in the mineral material, and use 200-mesh rubber powder to replace part of the mineral powder. (2) Weigh the dried and graded coarse and fine aggregates according to the design gradation requirements of each specimen, mix them evenly in a metal pan, and store the mineral powder separately. (3) After mixing the coarse and fine aggregates according to the proportion, pour them into the mixer and stir evenly. Keep the temperature at 180℃, add waste tire rubber powder with a particle size of 40 mesh, and continue stirring for 1 minute. (4) Add the modified asphalt and stir for 3 minutes; (5) Add mineral powder and waste tire rubber powder with a particle size of 200 mesh, stir for 1 min to obtain stable and durable high-content waste tire rubber powder modified asphalt mixture.

[0045] The mixture prepared in this embodiment has good stability and durability, and enables the large-scale use of waste tire rubber powder.

[0046] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

[0047] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A stable and durable high-content waste tire rubber powder modified asphalt, characterized in that, The raw materials, by weight percentage, are: 100 parts base asphalt; 40-50 parts waste tire rubber powder; 5-7 parts viscosity reducer; 0.1-0.8 parts crosslinking agent; and 1-2 parts reinforcing agent. The crosslinking agent is ABS, and the viscosity reducer is at least one of cycloalkyl rubber oil, alkane rubber oil, aromatic rubber oil, and polycyclic aromatic rubber oil.

2. The modified asphalt according to claim 1, characterized in that, The particle size of the waste tire rubber powder is 40-100 mesh. The reinforcing agent is selected from at least one of low-grade hard asphalt, ethylene-vinyl acetate plastic granules, polypropylene granules, and styrene-butadiene-styrene block copolymer granules; the base asphalt is 70# or 90# road petroleum asphalt.

3. The modified asphalt according to claim 1, characterized in that, The particle size of the waste tire rubber powder is 60 mesh.

4. The modified asphalt according to claim 1, characterized in that, The method for preparing the modified asphalt is as follows: (1) Place the container containing the base bitumen in a heating jacket and heat it until the temperature is stable at 130-150℃; (2) Stir continuously at a speed of 1000-1500 rpm, add viscosity reducer, maintain temperature and speed, and stir for 10-20 minutes; (3) Increase the temperature to 180-200℃, add waste tire rubber powder in 6-8 batches, and shear after each addition of waste tire rubber powder. Set the shearing speed to 3000-5000 rpm. (4) Add reinforcing agent, increase shearing speed to 6500-7500 rpm, and maintain high-speed shearing for 25-35 min at the temperature; (5) Add crosslinking agent and stir for 8-12 min, then shear again at a shear speed of 6500-7500 rpm for 15-25 min; (6) Then place it in a constant temperature chamber at 180-190℃ for 30-40 minutes to develop, and obtain stable and durable high-content waste tire rubber powder modified asphalt.

5. The modified asphalt according to claim 1, characterized in that, The segregation softening point difference of the modified asphalt is controlled within 1.0℃, and the softening point is greater than 85℃.

6. A stable and durable high-content waste tire rubber powder modified asphalt mixture, characterized in that, The product comprises the following components by weight percentage: 100 parts aggregate; 4-6 parts modified asphalt; 3-5 parts waste tire rubber powder; wherein the modified asphalt is the modified asphalt according to any one of claims 1-4.

7. The modified asphalt mixture according to claim 6, characterized in that, The waste tire rubber powder is divided into 3-5 parts with a particle size of 40 mesh and 200 mesh. The aggregate is divided into coarse aggregate and fine aggregate. The fine aggregate contains mineral powder, and the coarse aggregate contains minerals of different specifications.

8. A method for preparing a stable and durable high-content waste tire rubber powder modified asphalt mixture according to claim 7, characterized in that, The preparation method is as follows: (1) Place the aggregate and waste tire rubber powder together in an oven at 105℃±5℃ and dry them until constant weight. The heating time shall not be less than 4-6 hours. Use 40-mesh rubber powder to replace the stone of the same grade in the mineral material, and use 200-mesh rubber powder to replace part of the mineral powder. (2) Weigh the dried and graded coarse and fine aggregates according to the design gradation requirements of each specimen, mix them evenly in a metal pan, and store the mineral powder separately. (3) After mixing the coarse and fine aggregates according to the proportion, pour them into the mixer and stir evenly. Keep the temperature at 180℃±5℃, add waste tire rubber powder with a particle size of 40 mesh, and continue stirring for 1~2 minutes. (4) Add the modified asphalt and stir for 2-4 minutes; (5) Add mineral powder and waste tire rubber powder with a particle size of 200 mesh, stir for 1~2 minutes to obtain stable and durable high-content waste tire rubber powder modified asphalt mixture.

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