A recycled aramid fiber modified asphalt mixture and preparation method thereof

Abstract

The invention provides a recycled aramid fiber modified asphalt mixture and a preparation method thereof, which relates to the field of road engineering materials. The raw materials of the recycled aramid fiber modified asphalt mixture are composed of asphalt, aggregate, recycled aramid fiber and mineral powder; the amount of the recycled aramid fiber is 0.05%-0.1% of the total mass of the recycled aramid fiber modified asphalt mixture. The finally obtained recycled aramid fiber modified asphalt mixture has excellent high temperature rutting resistance, low temperature crack resistance and water damage resistance.

Description

Technical Field

[0001] The invention relates to the field of road engineering materials, and in particular to a recycled aramid fiber modified asphalt mixture and a preparation method thereof. Background Art

[0002] As a high-molecular flexible synthetic fiber, aramid fiber has excellent properties such as ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, and light weight. It is widely used in aerospace, electromechanical, construction, automobiles, sporting goods and other fields. Therefore, it is inevitable to produce a large amount of waste scraps of aramid fiber.

[0003] At present, landfill and incineration are the main methods for treating waste aramid materials. Among them, the incineration energy recovery method is to burn aramid waste as waste to generate electricity or heat. Although this method can reduce energy consumption to a certain extent, it will cause environmental pollution. The landfill treatment method will occupy land resources while causing environmental pollution.

[0004] Reference: Liang Bo, Zhang Haitao, Liu Zheng, et al. Research progress on the performance of fiber-modified asphalt mixtures [J]. China and Foreign Highways, 2023, 43(3): 1-16. The action mechanism and modification effect of basalt fiber, glass fiber, polyester fiber, wood fiber and aramid fiber on asphalt and asphalt mixtures were studied. And the reference: Hu Guopeng. Effect of aramid fiber on the durability of high modulus asphalt mixture [J]. Traffic World, 2024, (8): 23-25. The high modulus asphalt mixture prepared with asphalt, coarse aggregate, fine aggregate, mineral powder and aramid fiber as raw materials was disclosed, and the effect of aramid fiber on the durability of high modulus asphalt mixture was explored. In addition, prior art such as patent CN109437673A discloses a rubber powder modified asphalt mixture and a preparation method thereof, which is prepared from 100 parts of aggregate, 5 to 8 parts of mineral powder, 4 to 8 parts of modified asphalt, 5 to 25 parts of rubber powder, 1 to 5 parts of softener, and 1 to 5 parts of plasticizer according to the following method: first, the modified asphalt is prepared by a wet process: the base asphalt is heated to 140 to 150° C., liquid rubber, cis-polycyclooctene and stabilizer are added thereto, and the mixture is prepared by high-speed shearing and stirring; then, the mixture is prepared by a dry process: the aggregate and mineral powder are preheated to 175 to 180° C., and the prepared modified asphalt and rubber powder are preheated to 165 to 170° C.; first, the aggregate and rubber powder are added to a mixing pot, and then the modified asphalt, softener and plasticizer are added and mixed together, and finally, the mineral powder and fiber are added and mixed evenly to obtain a rubber powder modified asphalt mixture product. This invention improves the shortcomings of the current wet or dry process alone, improves the performance of rubber powder modified asphalt mixture, and can consume a large amount of waste tire rubber. However, the above two existing technologies have a high aramid content and are not suitable for the use of recycled aramid fibers with uneven lengths. The performance of the final asphalt mixture also has room for improvement.

[0005] Since aramid waste is mainly leftovers from the production process, its mechanical and chemical properties are well preserved and it has value for reuse. Therefore, it is very necessary to find a recycled aramid fiber modified asphalt mixture and a preparation method thereof. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a recycled aramid fiber modified asphalt mixture and a preparation method thereof. The finally obtained recycled aramid fiber modified asphalt mixture has excellent high-temperature rutting resistance, low-temperature crack resistance and water damage resistance.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] The invention provides a recycled aramid fiber modified asphalt mixture, the raw materials of which are composed of asphalt, aggregate, recycled aramid fiber and mineral powder; the admixture amount of the recycled aramid fiber is 0.05%-0.1% of the total mass of the recycled aramid fiber modified asphalt mixture.

[0009] Furthermore, the amount of the recycled aramid fiber is 0.075% of the total mass of the recycled aramid fiber modified asphalt mixture.

[0010] Furthermore, the mix types of the recycled aramid fiber modified asphalt mixture include fine-grained type, dense skeleton structure type or large-pore open-graded drainage type.

[0011] Preferably, the fine-grained type includes AC-13, AC-20 or GAC-20C, the dense skeleton structure type includes SMA-10 or SMA-13, and the large-pore open-graded drainage type includes OGFC-13 or OGFC-20.

[0012] It is worth mentioning that once the above mix type is determined, the proportion of asphalt, aggregate and mineral powder can be determined.

[0013] Furthermore, the asphalt includes base asphalt and / or modified asphalt; the aggregate includes one or more of basalt, limestone and diabase.

[0014] Furthermore, the base asphalt includes 70# asphalt and / or 90# asphalt, and the modified asphalt includes SBS modified asphalt and / or rubber modified asphalt.

[0015] Furthermore, the mineral powder includes limestone mineral powder.

[0016] Furthermore, the recycled aramid fiber is obtained by cutting aramid waste yarn through a mechanical recycling method, and the length of the recycled aramid fiber is 14-21 mm.

[0017] Preferably, the length of the recycled aramid fiber is 17 mm and / or 18 mm.

[0018] Furthermore, the present invention also provides a method for preparing the above-mentioned recycled aramid fiber modified asphalt mixture, comprising the following steps:

[0019] (1) Preheating aggregate, mineral powder and asphalt separately;

[0020] (2) Mix the preheated aggregate and asphalt, add the recycled aramid fiber, continue to stir, then add the preheated mineral powder, continue to stir, and obtain the product.

[0021] Furthermore, in step (1), the preheating temperature of the aggregate and mineral powder is 175°C for 4-5 hours, and the preheating time of the asphalt is 2-3 hours.

[0022] Furthermore, when the asphalt is base asphalt, the preheating temperature of the asphalt in step (1) is 145±5°C; when the asphalt is SBS modified asphalt, the preheating temperature of the asphalt in step (1) is 165±5°C.

[0023] Furthermore, the total time of the three stirrings in step (2) is 270 seconds. Preferably, the time of the three stirrings in step (2) is 90 seconds respectively.

[0024] In some specific embodiments, the preparation method comprises the following steps:

[0025] (1) Weigh each level of aggregate and mineral powder according to the mix ratio, and put them into a 175℃ oven for preheating for 4h-5h; at the same time, place the asphalt in the oven for heating, and adjust the heating time to an appropriate temperature for 2-3h to avoid asphalt aging. Weigh the recycled aramid fibers according to the mass percentage of the asphalt mixture.

[0026] (2) Asphalt mixture is prepared by mechanical mixing. The mixer is heated to an appropriate temperature for mixing and slurrying. This ensures that the fiber, asphalt and aggregate are fully activated and in contact with each other, while avoiding accelerated aging of asphalt and having high work efficiency. In the mixing process, the aggregate and asphalt are first mixed evenly for 90 seconds to ensure that the asphalt is in full contact with the aggregate; then the fiber is added and mixed for 90 seconds to ensure that the asphalt is in full contact with the fiber; finally, mineral powder is added and mixed for 90 seconds to enhance the asphalt's ability to wrap around the fiber. The total mixing time is 270 seconds to avoid asphalt aging caused by too long heating time.

[0027] Furthermore, the recycled aramid fiber modified asphalt mixture provided by the present invention or the recycled aramid fiber modified asphalt mixture prepared by the above preparation method can be used in asphalt road construction.

[0028] The technical effects achieved by the present invention are:

[0029] 1. The present invention has found a high-value application field and application method for aramid waste, providing a technically feasible, economical and convenient way to recycle aramid waste, and providing a new idea and reference for the sustainable development of the asphalt road field. At the same time, the use of recycled aramid fiber effectively enhances the various engineering properties of asphalt mixture, such as high-temperature rutting resistance, low-temperature crack resistance and water damage resistance.

[0030] 2. The length of the recycled aramid fiber used in the present invention is between 14-21 mm. Compared with normal aramid fiber, the length is more uneven and difficult to recycle. The method of the present invention can effectively utilize the recycled aramid fiber, realize the resource utilization of waste, and the final asphalt mixture has excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a test chart of recycled aramid fiber length.

[0032] Figure 2 This is the mix ratio and gradation curve of GAC-20C asphalt mixture.

[0033] Figure 3 It is a Marshall index diagram of recycled aramid fiber reinforced GAC-20C asphalt mixture; (a) is the data diagram of void ratio and gross volume density of Marshall specimens of GAC-20C asphalt mixture at different fiber contents, (b) is the data diagram of stability and splitting strength of Marshall specimens of GAC-20C asphalt mixture at different fiber contents, (c) is the data diagram of asphalt saturation and mineral void ratio of Marshall specimens of GAC-20C asphalt mixture at different fiber contents, and (d) is the data diagram of flow value and theoretical density of Marshall specimens of GAC-20C asphalt mixture at different fiber contents.

[0034] Figure 4 This is the freeze-thaw splitting data of GAC-20C asphalt mixture with different fiber content.

[0035] Figure 5 It is a high temperature stability index diagram of recycled aramid fiber reinforced GAC-20C asphalt mixture; (a) is the high temperature rutting data diagram of GAC-20C asphalt mixture at different fiber content, and (b) is the high temperature rutting deformation-loading time diagram of GAC-20C asphalt mixture at different fiber content.

[0036] Figure 6It is an index diagram of the low-temperature crack resistance of recycled aramid fiber reinforced GAC-20C asphalt mixture; (a) is a data diagram of the low-temperature semicircular splitting failure displacement of GAC-20C asphalt mixture at different temperatures and fiber contents, (b) is a data diagram of the maximum stress of the low-temperature semicircular splitting of GAC-20C asphalt mixture at different temperatures and fiber contents, (c) is a data diagram of the low-temperature semicircular splitting fracture energy of GAC-20C asphalt mixture at different temperatures and fiber contents, (d) is a load-displacement diagram of the low-temperature semicircular splitting of GAC-20C asphalt mixture at different fiber contents under -5°C, (e) is a load-displacement diagram of the low-temperature semicircular splitting of GAC-20C asphalt mixture at different fiber contents under 0°C, and (f) is a load-displacement diagram of the low-temperature semicircular splitting of GAC-20C asphalt mixture at different fiber contents under 5°C.

[0037] Figure 7 It is the mix proportion and gradation curve of SMA-13 ​​asphalt mixture.

[0038] Figure 8 It is a high temperature stability index diagram of recycled aramid fiber reinforced SMA-13 ​​asphalt mixture and lignin fiber reinforced SMA-13 ​​asphalt mixture; (a) is a high temperature rutting data diagram of SMA-13 ​​asphalt mixture with different fibers, and (b) is a high temperature rutting deformation-loading time diagram of SMA-13 ​​asphalt mixture with different fibers.

[0039] Fig. 9 It is a low-temperature crack resistance index diagram of recycled aramid fiber reinforced SMA-13 ​​asphalt mixture and lignin fiber reinforced SMA-13 ​​asphalt mixture; (a) is a low-temperature semicircular splitting fracture energy data diagram of SMA-13 ​​asphalt mixture with different temperatures and different fibers, (b) is a low-temperature semicircular splitting load-displacement diagram of SMA-13 ​​asphalt mixture with different fibers under -5°C conditions, (c) is a low-temperature semicircular splitting load-displacement diagram of SMA-13 ​​asphalt mixture with different fibers under 0°C conditions, and (d) is a low-temperature semicircular splitting load-displacement diagram of SMA-13 ​​asphalt mixture with different fibers under 5°C conditions. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0042] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs.

[0043] It is worth noting that the mineral powder used in the present invention is limestone mineral powder, and the remaining raw materials are common commercial products, so their sources are not specifically limited.

[0044] The properties of the recycled aramid fiber and lignin fiber used in the present invention are shown in the table below, and the length test diagram of the recycled aramid fiber is shown in Figure 1 .

[0045] Table 1

[0046]

[0047] Example 1

[0048] A recycled aramid fiber reinforced GAC-20C asphalt mixture, the preparation method specifically comprises the following steps:

[0049] (1) Weigh each level of aggregate and mineral powder according to the mix ratio, and put them into a 175℃ oven for preheating for 4h-5h; at the same time, place the asphalt in the oven for heating, and adjust the heating time to an appropriate temperature for 2-3h to avoid asphalt aging. Weigh the recycled aramid fibers according to the mass percentage of the asphalt mixture.

[0050] (2) Asphalt mixture is prepared by mechanical mixing. The mixer is heated to an appropriate temperature for mixing and slurrying. This ensures that the fiber, asphalt and aggregate are fully activated and in contact with each other, while avoiding accelerated aging of asphalt and having high work efficiency. In the mixing process, the aggregate and asphalt are first mixed evenly for 90 seconds to ensure that the asphalt is in full contact with the aggregate; then the fiber is added and mixed for 90 seconds to ensure that the asphalt is in full contact with the fiber; finally, mineral powder is added and mixed for 90 seconds to enhance the asphalt's ability to wrap around the fiber. The total mixing time is 270 seconds to avoid asphalt aging caused by too long heating time.

[0051] Among them, the dosage of recycled aramid fiber is 0.075% of the total mass of the recycled aramid fiber modified asphalt mixture. The asphalt is SBS (ID) modified asphalt, which is provided by Guangdong Xinyue Jiafu Asphalt Co., Ltd.; the aggregate is specifically limestone with particle size specifications of 3-5mm, 5-10mm and 10-20mm, which is provided by Xindian Stone Yard; the mineral powder is provided by Jiangxi Yonglun New Materials Technology Co., Ltd.

[0052] The obtained recycled aramid fiber reinforced GAC-20C asphalt mixture was named AF-0.075%.

[0053] Example 2

[0054] A recycled aramid fiber reinforced GAC-20C asphalt mixture, which is different from Example 1 only in that the amount of recycled aramid fiber is 0.05% of the total mass of the recycled aramid fiber modified asphalt mixture. The preparation method is the same as that of Example 1.

[0055] The obtained recycled aramid fiber reinforced GAC-20C asphalt mixture was named AF-0.05%.

[0056] Example 3

[0057] A recycled aramid fiber reinforced GAC-20C asphalt mixture, which is different from Example 1 only in that the amount of recycled aramid fiber added is 0.1% of the total mass of the recycled aramid fiber modified asphalt mixture. The preparation method is the same as that of Example 1.

[0058] The obtained recycled aramid fiber reinforced GAC-20C asphalt mixture was named AF-0.1%.

[0059] Example 4

[0060] A recycled aramid fiber reinforced SMA-13 ​​asphalt mixture, which is different from Example 1 only in that the prepared material is SMA-13 ​​asphalt mixture;

[0061] Among them, the asphalt used is SBS (ID) modified asphalt, provided by Guangdong Xinyue Jiafu Asphalt Co., Ltd.; the aggregate is basalt with particle size specifications of 3-5mm, 5-10mm and 10-15mm, provided by Jiangxi Basalt Mining Co., Ltd.; the mineral powder is provided by Jiangxi Yonglun New Materials Technology Co., Ltd.

[0062] Comparative Example 1

[0063] An asphalt mixture, which is different from Example 1 only in that the amount of recycled aramid fiber added is 0.

[0064] The obtained recycled aramid fiber reinforced GAC-20C asphalt mixture was named AF-0%.

[0065] Comparative Example 2

[0066] The only difference from Example 4 is that the recycled aramid fiber is replaced by lignin fiber with a dosage of 0.35% (it is worth noting that this dosage is commonly used in SAM-13 asphalt mixture in existing technical projects).

[0067] The final GAC-20C asphalt mixture mix proportion gradation curves obtained in Examples 1-3 and Comparative Example 1 (i.e., different recycled aramid fiber dosages) are shown in Figure 2 , the Marshall index diagram of recycled aramid fiber reinforced GAC-20C asphalt mixture is detailed in Figure 3 The freeze-thaw splitting data of GAC-20C asphalt mixture at different fiber content is shown in Figure 4 , the high temperature stability index of recycled aramid fiber reinforced GAC-20C asphalt mixture is shown in Figure 5 , the low temperature crack resistance index of recycled aramid fiber reinforced GAC-20C asphalt mixture is shown in Figure 6 .

[0068] The SMA-13 ​​asphalt mixture mix proportion gradation curves obtained in Example 4 and Comparative Example 2 are shown in Figure 7 , the high temperature stability index of recycled aramid fiber reinforced SMA-13 ​​asphalt mixture and lignin fiber reinforced SMA-13 ​​asphalt mixture is shown in Figure 8 , the low temperature crack resistance performance index of recycled aramid fiber reinforced SMA-13 ​​asphalt mixture and lignin fiber reinforced SMA-13 ​​asphalt mixture is shown in Fig. 9 .

[0069] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A recycled aramid fiber modified asphalt mixture, characterized in that: The raw materials consist of asphalt, aggregate, recycled aramid fiber and mineral powder; the dosage of the recycled aramid fiber is 0.075% of the total mass of the recycled aramid fiber modified asphalt mixture; the measured density of the recycled aramid fiber is 2.510; the recycled aramid fiber is obtained by cutting aramid waste fibers through a mechanical recycling method, and has a length of 14-21 mm; the mix ratio of the recycled aramid fiber modified asphalt mixture is GAC-20C.

2. The recycled aramid fiber modified asphalt mixture according to claim 1, characterized in that: The asphalt includes base asphalt and / or modified asphalt; the aggregate includes one or more of basalt, limestone and diabase.

3. The recycled aramid fiber modified asphalt mixture according to claim 2, characterized in that: The base asphalt includes 70# asphalt and / or 90# asphalt, and the modified asphalt includes SBS modified asphalt and / or rubber modified asphalt.

4. The recycled aramid fiber modified asphalt mixture according to claim 1, characterized in that: The length of the recycled aramid fiber is 17 mm and / or 18 mm.

5. The method for preparing the recycled aramid fiber modified asphalt mixture according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preheating aggregate, mineral powder and asphalt separately; (2) Mix the preheated aggregate and asphalt, add the recycled aramid fiber, continue to stir, then add the preheated mineral powder, continue to stir, and obtain the product.

6. The preparation method according to claim 5, characterized in that: In step (1), the preheating temperature of the aggregate and mineral powder is 175°C for 4-5 hours, and the preheating time of the asphalt is 2-3 hours.

7. Use of the recycled aramid fiber modified asphalt mixture according to any one of claims 1 to 4 or the recycled aramid fiber modified asphalt mixture prepared by the preparation method according to any one of claims 5 to 6 in asphalt road construction.

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