An asphalt mixture resistant to low-temperature cracking and its preparation method

Abstract

An asphalt mixture resistant to low-temperature cracking and its preparation method, which relates to an asphalt mixture and its preparation method. The purpose of the present invention is to solve the problem that the low-temperature cracking resistance of existing asphalt and modified asphalt is still not ideal enough, and a large amount of it needs to be used in asphalt mixtures, which increases the cost of asphalt pavements. An asphalt mixture resistant to low-temperature cracking, by weight, comprises 4.5 to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 to 0.6 parts of SBS-grafted hyperbranched polyglycerol, and 0.3 to 0.4 parts of polyester fiber. The preparation method of the present invention is simple. By using a small amount of SBS-grafted hyperbranched polyglycerol, the cost is reduced, the service quality of the asphalt mixture pavement is improved, and it has broad application prospects. The present invention can obtain an asphalt mixture resistant to low-temperature cracking.

Description

Technical Field

[0001] The present invention relates to an asphalt mixture and a preparation method thereof. Background Art

[0002] The cracking of asphalt pavements directly affects the service life of asphalt pavements. It is mainly caused by two factors. On the one hand, it is fatigue cracking caused by long-term load action. On the other hand, it is temperature cracking caused by low winter temperatures. Fatigue cracking occurs at the end of the designed service life of the pavement, while temperature cracking will appear in the early stage of pavement use in areas with low winter temperatures. In the seasonal freezing areas in the north of China, due to climate conditions, the temperature changes greatly, and the temperature difference between the four seasons is large, resulting in the extremely common occurrence of low-temperature cracks in asphalt pavements, and rutting has also become a serious form of damage to asphalt pavements. Therefore, the low-temperature crack resistance performance of asphalt pavements directly affects the service quality and service life of asphalt pavements.

[0003] As a viscoelastic material, asphalt has a relatively low relative molecular weight and a wide distribution range, and is highly sensitive to temperature. It becomes soft and sticky at high temperatures, brittle and easy to crack at low temperatures, and has poor fatigue resistance performance, which to a certain extent restricts the development of asphalt and its mixtures. Therefore, modifying asphalt has become an effective method. Asphalt modification refers to doping one or several modified additive materials in the matrix asphalt mixture, and through appropriate processing techniques, making the modified materials melt and disperse in the matrix asphalt or matrix asphalt mixture to form a modified asphalt mixture.

[0004] The modified asphalt produced in China mainly has three categories: one is rubber-based, including natural rubber (NR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), etc. Represented by styrene-butadiene rubber (SBR), it mainly improves the low-temperature performance of asphalt. The second is thermoplastic rubber-based, including styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS). The asphalt modified by this kind of rubber has good high and low temperature performance. The third is thermoplastic resin-based, including EVA, polyethylene, polypropylene, polyvinyl acetate, atactic polypropylene (APP), etc.

[0005] However, the above-mentioned modified asphalt still has an unsatisfactory low-temperature crack resistance performance and needs to be used in large quantities in asphalt mixtures, which increases the cost of asphalt pavements. Summary of the Invention

[0006] The object of the present invention is to solve the problem that the existing asphalt and modified asphalt still have an unsatisfactory low-temperature crack resistance performance and need to be used in large quantities in asphalt mixtures, which increases the cost of asphalt pavements, and to provide an asphalt mixture with low-temperature crack resistance and a preparation method thereof.

[0007] An anti-low-temperature-cracking asphalt mixture, by weight, comprises 4.5 to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 to 0.6 parts of SBS-grafted hyperbranched polyglycerol, and 0.3 to 0.4 parts of polyester fiber;

[0008] The preparation method of the described SBS-grafted hyperbranched polyglycerol is as follows:

[0009] ①. Dissolve hyperbranched polyglycerol in N,N-dimethylformamide, then add a silane coupling agent, perform ultrasonic treatment, and then reflux and react in an oil bath at 100-120 °C. After the reaction ends, wash with N,N-dimethylformamide and dry to obtain amino-functionalized hyperbranched polyglycerol;

[0010] ②. Grind maleic anhydride-grafted SBS using a colloid mill to obtain a maleic anhydride-grafted SBS dispersion; add the maleic anhydride-grafted SBS dispersion to toluene for swelling to obtain swollen maleic anhydride-grafted SBS;

[0011] ③. Add the amino-functionalized hyperbranched polyglycerol to N,N-dimethylformamide, perform ultrasonic treatment, then add the swollen maleic anhydride-grafted SBS, stir evenly, and then react in an oil bath at 100-120 °C. Cool to 60-80 °C, then add a catalyst and continue to react at 60-80 °C. After the reaction ends, wash with anhydrous ethanol and distilled water, and then dry to obtain SBS-grafted hyperbranched polyglycerol.

[0012] A preparation method of an anti-low-temperature-cracking asphalt mixture comprises the following steps:

[0013] I. Weigh 4.5 to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 to 0.6 parts of SBS-grafted hyperbranched polyglycerol, and 0.3 to 0.4 parts of polyester fiber by weight;

[0014] II. Mix 100 parts of aggregate and 0.3 to 0.4 parts of polyester fiber at 160-180 °C to obtain a mixture, keep it warm for standby; heat the asphalt to 160-180 °C, keep it warm for standby; heat the SBS-grafted hyperbranched polyglycerol to 160-180 °C, keep it warm for standby;

[0015] III. Add the asphalt at 160-180 °C to the mixture at 160-180 °C, stir at 160-180 °C for 5-15 minutes, then add the SBS-grafted hyperbranched polyglycerol at 160-180 °C, mix at 160-180 °C for 20-30 minutes, and cool to room temperature to obtain an anti-low-temperature-cracking asphalt mixture.

[0016] Advantages of the present invention:

[0017] 1. The present invention uses gravel, stone chips and mineral powder with different particle sizes as the supporting skeleton of the asphalt mixture, improving the stability of the asphalt mixture.

[0018] 2. The present invention uses maleic anhydride grafted SBS. Compared with SBS, maleic anhydride grafted SBS improves the polarity of SBS and can chemically bond with amino-functionalized hyperbranched polyglycerol, thereby preparing SBS grafted hyperbranched polyglycerol. Adding SBS grafted hyperbranched polyglycerol to the asphalt mixture, hyperbranched polyglycerol has multiple hydroxyl groups, which can form a stable spatial network structure between macromolecules in the solidified state of the asphalt. Mineral powder can be filled in the spatial network, and at the same time can promote the dispersion of SBS and improve its compatibility, thereby improving the ductility and low-temperature cracking resistance of the asphalt mixture, improving the service quality of the asphalt mixture, and extending the service life of the asphalt mixture pavement.

[0019] 3. The preparation method of the present invention is simple, uses a small amount of SBS grafted hyperbranched polyglycerol, reduces costs, improves the service quality of the asphalt mixture pavement, and has broad application prospects.

[0020] The present invention can obtain an asphalt mixture with low-temperature cracking resistance. Specific Embodiments

[0021] Specific Embodiment 1: An asphalt mixture with low-temperature cracking resistance according to this embodiment, by weight, includes 4.5 to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 to 0.6 parts of SBS grafted hyperbranched polyglycerol, and 0.3 to 0.4 parts of polyester fiber.

[0022] The preparation method of the described SBS grafted hyperbranched polyglycerol is as follows:

[0023] ① Dissolve hyperbranched polyglycerol in N,N-dimethylformamide, then add a silane coupling agent, ultrasonicate, and then reflux in an oil bath at 100 - 120 °C. After the reaction, wash with N,N-dimethylformamide and dry to obtain amino-functionalized hyperbranched polyglycerol.

[0024] ② Grind maleic anhydride grafted SBS with a colloid mill to obtain a maleic anhydride grafted SBS dispersion. Add the maleic anhydride grafted SBS dispersion to toluene for swelling to obtain swollen maleic anhydride grafted SBS.

[0025] ③ Add amino-functionalized hyperbranched polyglycerol to N,N-dimethylformamide, ultrasonicate, then add the swollen maleic anhydride grafted SBS, stir evenly, and then react in an oil bath at 100 - 120 °C. Cool to 60 - 80 °C, then add a catalyst and continue to react at 60 - 80 °C. After the reaction, wash with anhydrous ethanol and distilled water and then dry to obtain SBS grafted hyperbranched polyglycerol.

[0026] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the aggregate is composed of 45 to 55 parts by weight of gravel with a particle size of 10 to 15 mm, 22 to 32 parts by weight of gravel with a particle size of 5 to 10 mm, 10 to 14 parts by weight of stone chips with a particle size of 0.075 to 3 mm, and 9 to 13 parts by weight of mineral powder. Other steps are the same as those in Embodiment 1.

[0027] Embodiment 3: The difference between this embodiment and either Embodiment 1 or Embodiment 2 is that the gravel is limestone gravel; the stone chips are limestone stone chips; the mineral powder is limestone mineral powder. Other steps are the same as those in Embodiment 1 or Embodiment 2.

[0028] Embodiment 4: The difference between this embodiment and any one of Embodiments 1 to 3 is that the length of the polyester fiber is 6 to 8 mm, the diameter is 0.015 to 0.020 mm, and the tensile strength is greater than 800 MPa

[0029] , and the color volume basically does not change after 2 hours at 210°C. Other steps are the same as those in Embodiments 1 to 3.

[0030] Embodiment 5: The difference between this embodiment and any one of Embodiments 1 to 4 is that the asphalt is 90# asphalt or SBS modified asphalt. Other steps are the same as those in Embodiments 1 to 4.

[0031] Embodiment 6: The difference between this embodiment and any one of Embodiments 1 to 5 is that the silane coupling agent in step ① is KH550 or KH560; the mass-to-volume ratio of the hyperbranched polyglycerol to N,N-dimethylformamide in step ① is (1 g to 8 g):100 mL; the mass-to-volume ratio of the silane coupling agent to N,N-dimethylformamide in step ① is (1 g to 3 g):100 mL. Other steps are the same as those in Embodiments 1 to 5.

[0032] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is that in step ①, the hyperbranched polyglycerol is dissolved in N,N-dimethylformamide, then the silane coupling agent is added, and ultrasonic treatment is carried out for 20 to 40 minutes, and then reflux reaction is carried out in an oil bath at 100 to 120°C for 6 to 8 hours. After the reaction is completed, it is washed 2 to 4 times with N,N-dimethylformamide, and then dried at 100°C for 6 to 8 hours to obtain amino-functionalized hyperbranched polyglycerol; the rotation speed of the grinding in step ② is 3000 to 4000 r / min, and the grinding time is 20 to 40 minutes; the swelling time in step ② is 2 to 6 hours. Other steps are the same as those in Embodiments 1 to 6.

[0033] Specific Embodiment VIII: The difference between this embodiment and any one of Embodiments 1 to 7 is as follows: In step ③, the mass ratio of the aminated hyperbranched polyglycerol to the swollen maleic anhydride grafted SBS is (1-2):10; in step ③, the mass ratio of the aminated hyperbranched polyglycerol to the volume of N,N-dimethylformamide is (0.5 g-1 g):100 mL; in step ③, the mass ratio of the catalyst to the swollen maleic anhydride grafted SBS is (0.5-1):10. Other steps are the same as those in Embodiments 1 to 7.

[0034] Specific Embodiment IX: The difference between this embodiment and any one of Embodiments 1 to 8 is as follows: In step ③, the aminated hyperbranched polyglycerol is added to N,N-dimethylformamide and ultrasonically treated for 10 min to 20 min, then the swollen maleic anhydride grafted SBS is added and stirred evenly, and then reacted in an oil bath at 100-120 °C for 40 min to 80 min. After cooling to 60 °C to 80 °C, the catalyst is added and the reaction continues at 60 °C to 80 °C for 10 h to 20 h. After the reaction is completed, it is washed alternately with absolute ethanol and distilled water twice respectively, and then dried in a vacuum drying oven to obtain SBS grafted hyperbranched polyglycerol; the catalyst in step ③ is triethylamine. Other steps are the same as those in Embodiments 1 to 8.

[0035] Specific Embodiment X: This embodiment is a preparation method of an anti-low-temperature cracking asphalt mixture, which includes the following steps:

[0036] I. Weigh 4.5 parts to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 part to 0.6 part of SBS grafted hyperbranched polyglycerol, and 0.3 part to 0.4 part of polyester fiber by weight;

[0037] II. Mix 100 parts of aggregate and 0.3 part to 0.4 part of polyester fiber at 160 °C to 180 °C to obtain a mixture, keep it warm for standby; heat the asphalt to 160 °C to 180 °C, keep it warm for standby; heat the SBS grafted hyperbranched polyglycerol to 160 °C to 180 °C, keep it warm for standby;

[0038] III. Add the asphalt at 160 °C to 180 °C to the mixture at 160 °C to 180 °C, stir at 160 °C to 180 °C for 5 min to 15 min, then add the SBS grafted hyperbranched polyglycerol at 160 °C to 180 °C, mix at 160 °C to 180 °C for 20 min to 30 min, and cool to room temperature to obtain an anti-low-temperature cracking asphalt mixture.

[0039] The following examples are used to verify the beneficial effects of the present invention:

[0040] Example 1: A preparation method of an asphalt mixture resistant to low-temperature cracking is completed according to the following steps:

[0041] I. Preparation of SBS-grafted hyperbranched polyglycerol:

[0042] ①. Dissolve hyperbranched polyglycerol in N,N-dimethylformamide, then add a silane coupling agent, ultrasonicate for 20 min, and then reflux and react in an oil bath at 100 °C for 7 h; after the reaction, wash twice with N,N-dimethylformamide and then dry at 100 °C for 8 h to obtain amino-functionalized hyperbranched polyglycerol;

[0043] The silane coupling agent described in step I① is KH550;

[0044] The mass ratio of the hyperbranched polyglycerol to the volume of N,N-dimethylformamide described in step I① is 5 g:100 mL;

[0045] The mass ratio of the silane coupling agent to the volume of N,N-dimethylformamide described in step I① is 2 g:100 mL;

[0046] ②. Grind maleic anhydride-grafted SBS with a colloid mill for 40 min to obtain a maleic anhydride-grafted SBS dispersion; add the maleic anhydride-grafted SBS dispersion to toluene and swell for 5 h to obtain swollen maleic anhydride-grafted SBS;

[0047] The rotation speed of the grinding described in step I② is 4000 r / min;

[0048] ③. Add the amino-functionalized hyperbranched polyglycerol to N,N-dimethylformamide, ultrasonicate for 20 min, then add the swollen maleic anhydride-grafted SBS, stir evenly, react in an oil bath at 100 °C for 60 min, then cool down to 60 °C, add triethylamine, and continue to react at 60 °C for 15 h. After the reaction, wash twice alternately with anhydrous ethanol and distilled water, and then dry in a vacuum drying oven to obtain SBS-grafted hyperbranched polyglycerol;

[0049] The mass ratio of the amino-functionalized hyperbranched polyglycerol to the swollen maleic anhydride-grafted SBS described in step I③ is 1.5:10;

[0050] The mass ratio of the amino-functionalized hyperbranched polyglycerol to the volume of N,N-dimethylformamide described in step I③ is 0.5 g:100 mL;

[0051] The mass ratio of triethylamine to the swollen maleic anhydride-grafted SBS described in step I③ is 0.8:10;

[0052] II. Weigh 5 parts of asphalt, 100 parts of aggregate, 0.5 part of SBS-grafted hyperbranched polyglycerol, and 0.4 part of polyester fiber by weight;

[0053] III. Mix 100 parts of aggregate and 0.4 part of polyester fiber at 170 °C to obtain a mixture, keep it warm for standby; heat the asphalt to 170 °C, keep it warm for standby; heat the SBS-grafted hyperbranched polyglycerol to 170 °C, keep it warm for standby;

[0054] IV. Add the asphalt at 170 °C to the mixture at 170 °C, stir at 170 °C for 10 min, then add the SBS-grafted hyperbranched polyglycerol at 170 °C, mix at 170 °C for 30 min, and cool to room temperature to obtain an asphalt mixture with resistance to low-temperature cracking.

[0055] Comparative Example 1: The preparation method of the asphalt mixture is as follows:

[0056] I. Weigh 5 parts of asphalt, 100 parts of aggregate, 0.5 part of SBS, and 0.4 part of polyester fiber by weight;

[0057] II. Mix 100 parts of aggregate and 0.4 part of polyester fiber at 170 °C to obtain a mixture, keep it warm for standby; heat the asphalt to 170 °C, keep it warm for standby; heat the SBS to 170 °C, keep it warm for standby;

[0058] IV. Add the asphalt at 170 °C to the mixture at 170 °C, stir at 170 °C for 10 min, then add the SBS at 170 °C, mix at 170 °C for 30 min, and cool to room temperature to obtain an asphalt mixture.

[0059] The polyester fiber described in Example 1 and Comparative Example 1 has a length of 6 - 8 mm, a diameter of 0.015 - 0.020 mm, a tensile strength greater than 800 MPa, and basically no change in color volume at 210 °C for 2 h.

[0060] The asphalt described in Example 1 and Comparative Example 1 is 90# asphalt.

[0061] Table 1 shows that the aggregate in Example 1 and Comparative Example 1 is limestone, and the particle size distribution of the aggregate is shown in Table 1;

[0062] Table 1

[0063]

[0064] Performance test:

[0065] According to JTJ052 - 2000 "Test Procedures for Bitumen and Bituminous Mixtures in Highway Engineering", the performance of the bituminous mixture with low - temperature cracking resistance prepared in Example 1 and the bituminous mixture prepared in Comparative Example 1 was tested, as shown in Table 2;

[0066] Table 2

[0067] Example 1 Comparative Example 1 Porosity / % 2.7 4.3 Dynamic stability times / mm 9356 6931 Low-temperature bending failure strain / με 3865 2937 Freeze-thaw splitting tensile strength ratio / % 96.1 90.5

[0068] It can be seen from Table 2 that: using maleic anhydride - grafted SBS in Example 1 significantly improved the low - temperature cracking resistance of the bituminous mixture compared with SBS used in Comparative Example 1, improved the service quality of the bituminous mixture, extended the service life of the bituminous mixture pavement, and has broad application prospects.

Claims

1. An asphalt mixture resistant to low-temperature cracking, characterized in that The mixture, by weight parts, comprises 4.5 to 5.5 parts of asphalt, 100 parts of aggregate, 0.5 to 0.6 parts of SBS-grafted hyperbranched polyglycerol, and 0.3 to 0.4 parts of polyester fiber; The preparation method of the described SBS-grafted hyperbranched polyglycerol is as follows: ① Dissolve hyperbranched polyglycerol in N,N-dimethylformamide, then add a silane coupling agent, ultrasonicate, and then reflux in an oil bath at 100 - 120 °C; after the reaction, wash with N,N-dimethylformamide and dry to obtain amino-functionalized hyperbranched polyglycerol; ② Grind maleic anhydride-grafted SBS using a colloid mill to obtain a maleic anhydride-grafted SBS dispersion; add the maleic anhydride-grafted SBS dispersion to toluene for swelling to obtain swollen maleic anhydride-grafted SBS; ③ Add the amino-functionalized hyperbranched polyglycerol to N,N-dimethylformamide, ultrasonicate, then add the swollen maleic anhydride-grafted SBS, stir evenly, and then react in an oil bath at 100 - 120 °C, cool to 60 - 80 °C, add a catalyst, and continue to react at 60 - 80 °C. After the reaction, wash with absolute ethanol and distilled water, and then dry to obtain SBS-grafted hyperbranched polyglycerol.

2. The asphalt mixture with low-temperature cracking resistance according to claim 1, characterized in that The described aggregate, by weight parts, consists of 45 to 55 parts of crushed stone with a particle size of 10 - 15 mm, 22 to 32 parts of crushed stone with a particle size of 5 - 10 mm, 10 to 14 parts of stone chips with a particle size of 0.075 - 3 mm, and 9 to 13 parts of mineral powder.

3. The asphalt mixture with resistance to low-temperature cracking according to claim 2, wherein The described crushed stone is limestone crushed stone; the described stone chips are limestone stone chips; the described mineral powder is limestone mineral powder.

4. An anti-low-temperature cracking asphalt mixture according to claim 1, characterized in that The described polyester fiber has a length of 6 - 8 mm, a diameter of 0.015 - 0.020 mm, and a tensile strength greater than 800 MPa.

5. The asphalt mixture with low-temperature cracking resistance according to claim 1, characterized in that The described asphalt is 90# asphalt.

6. The asphalt mixture with resistance to low-temperature cracking according to claim 1, characterized in that In step ①, the silane coupling agent is KH550 or KH560; in step ①, the mass ratio of the hyperbranched polyglycerol to the volume of N,N-dimethylformamide is (1 g - 8 g):100 mL; in step ①, the mass ratio of the silane coupling agent to the volume of N,N-dimethylformamide is (1 g - 3 g):100 mL.

7. The asphalt mixture with low-temperature cracking resistance according to claim 1, characterized in that In step ①, dissolve hyperbranched polyglycerol in N,N-dimethylformamide, then add a silane coupling agent, ultrasonicate for 20 - 40 min, and then reflux in an oil bath at 100 - 120 °C for 6 - 8 h; after the reaction, wash with N,N-dimethylformamide 2 - 4 times, and then dry at 100 °C for 6 - 8 h to obtain amino-functionalized hyperbranched polyglycerol; in step ②, the rotation speed of the grinding is 3000 - 4000 r / min, and the grinding time is 20 - 40 min; in step ②, the swelling time is 2 - 6 h.

8. The asphalt mixture with low-temperature cracking resistance according to claim 1, characterized in that The mass ratio of the aminated hyperbranched polyglycerol described in step ③ to the swollen maleic anhydride grafted SBS is (1-2):10; the mass ratio of the aminated hyperbranched polyglycerol described in step ③ to the volume of N,N-dimethylformamide is (0.5 g-1 g):100 mL; the mass ratio of the catalyst described in step ③ to the swollen maleic anhydride grafted SBS is (0.5-1):

10.

9. An anti-low-temperature cracking asphalt mixture according to claim 1, wherein In step ③, the aminated hyperbranched polyglycerol is added to N,N-dimethylformamide and ultrasonicated for 10 min-20 min, then the swollen maleic anhydride grafted SBS is added, stirred evenly, and then reacted in an oil bath at 100-120 °C for 40 min-80 min. The temperature is lowered to 60 °C-80 °C, and then the catalyst is added, and the reaction continues at 60 °C-80 °C for 10 h-20 h. After the reaction is completed, it is washed alternately with anhydrous ethanol and distilled water twice each, and then dried in a vacuum drying oven to obtain SBS grafted hyperbranched polyglycerol; the catalyst described in step ③ is triethylamine.

10. The preparation method of an anti-low-temperature cracking asphalt mixture according to any one of claims 1 to 9, characterized in that The preparation method includes the following steps: I. Weigh 4.5 parts-5.5 parts of asphalt, 100 parts of aggregate, 0.5 parts-0.6 parts of SBS grafted hyperbranched polyglycerol, and 0.3 parts-0.4 parts of polyester fiber by weight. II. Mix 100 parts of aggregate and 0.3 parts-0.4 parts of polyester fiber at 160 °C-180 °C to obtain a mixture, keep it warm for standby; heat the asphalt to 160 °C-180 °C, keep it warm for standby; heat the SBS grafted hyperbranched polyglycerol to 160 °C-180 °C, keep it warm for standby. III. Add the asphalt at 160 °C-180 °C to the mixture at 160 °C-180 °C, stir at 160 °C-180 °C for 5 min-15 min, then add the SBS grafted hyperbranched polyglycerol at 160 °C-180 °C, mix at 160 °C-180 °C for 20 min-30 min, and cool to room temperature to obtain an asphalt mixture with resistance to low-temperature cracking.

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