Method for preparing modified asphalt by compounding polypropylene, ethylene-vinyl acetate polymer and desulfurized rubber powder

Abstract

The invention provides a method for preparing modified asphalt by compounding polypropylene, an ethylene-vinyl acetate polymer and desulfurized rubber powder, which comprises the following steps: weighing a polypropylene and ethylene-vinyl acetate mixture, primarily mixing, transferring into a Haake torque rheometer, mixing for 10-15 minutes at the temperature of 160-200 DEG C, transferring into an open mill, and mixing for 10-15 minutes at the temperature of 160-200 DEG C to obtain the modified asphalt. Transferring the polymer in a molten state into an open mill, rolling into sheets, cooling, transferring into a granulator, and cutting into particles with uniform sizes; the preparation method comprises the following steps: heating matrix asphalt to 150 DEG C, adding desulfurized rubber powder and polypropylene and ethylene-vinyl acetate polymer particles, raising the temperature to 180-200 DEG C, and carrying out a stirring reaction in a stirrer for 30-60 min; and then transferring into a shearing machine, and swelling and developing for 30-60 minutes at 180-200 DEG C to obtain the polypropylene, ethylene-vinyl acetate and desulfurized rubber powder compound modified asphalt with better storage stability and high and low temperature performance. Balanced optimization of high-temperature and low-temperature performance of the modified asphalt can be achieved, SBS is replaced, and economic benefits are improved.

Description

Technical Field

[0001] This invention relates to the field of polymer rubber composite modified asphalt technology, and in particular to a method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymers with desulfurized rubber powder. Background Technology

[0002] Asphalt pavement is widely used in road engineering due to its good driving comfort and ease of construction, but its performance is significantly affected by ambient temperature. At low temperatures, asphalt materials harden and become brittle, easily cracking; while in hot seasons, repeated vehicle loads can cause plastic deformation, leading to rutting. These not only affect driving safety and comfort but also significantly shorten the service life of the pavement. Adding polymer modifiers such as styrene-butadiene-styrene block copolymer (SBS) and chromium chromate (CR) to the base asphalt can significantly improve the high and low temperature performance of asphalt materials, enhance low-temperature crack resistance and high-temperature rutting resistance, and improve fatigue durability, making it an effective technical approach to improve the service performance of asphalt pavement. However, SBS is expensive, significantly increasing the production cost of modified asphalt. It is also prone to degradation under long-term ultraviolet radiation and oxygen exposure, leading to aging and performance degradation. Furthermore, it is susceptible to softening and deformation under high-temperature conditions, resulting in decreased high-temperature stability and rutting resistance. Therefore, developing SBS alternatives for modified asphalt is of great significance.

[0003] In recent years, various types of plastics have generated a large amount of household waste, such as ethylene-vinyl acetate copolymer (EVA), polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), which have had a significant impact on the environment. Therefore, research on the reuse of waste plastics in the asphalt industry has received increasing attention. Currently, polypropylene (PP) and ethylene-vinyl acetate copolymer (EVA) can be used as asphalt modifiers. PP has excellent heat resistance and corrosion resistance, which can significantly improve the high-temperature stability, rutting resistance, and aging resistance of asphalt, extending its service life, while also enhancing its rigidity and strength. However, the addition of PP may reduce the low-temperature performance of modified asphalt, while EVA can effectively improve the elasticity and flexibility of asphalt, especially significantly improving crack resistance and reducing cracks caused by permanent deformation under low-temperature conditions. In summary, the combined use of PP and EVA is expected to achieve a synergistic effect, but currently, no research has been conducted on methods for using PP and EVA to replace SBS in the preparation of modified asphalt. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing DCR modified asphalt using PP / EVA composite material to replace SBS, thereby achieving the replacement of SBS modified asphalt and solving the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh the mixture of polypropylene and ethylene-vinyl acetate, mix them initially, and then transfer them together into a Hacker torque rheometer. Mix them at 160-200 ℃ for 10-15 min to obtain a fully mixed polypropylene and ethylene-vinyl acetate polymer.

[0006] Step 2: Transfer the polypropylene and ethylene-vinyl acetate polymer from Step 1 into a two-roll mill. The molten polymer is calendered into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized polypropylene and ethylene-vinyl acetate polymer granules.

[0007] Step 3: Take the base asphalt, heat it to 150℃, add the desulfurized rubber powder and the polypropylene and ethylene-vinyl acetate polymer particles obtained in Step 2, raise the temperature to 180-200℃, and stir the reaction under a stirrer for 30-60 minutes to initially obtain the modified asphalt.

[0008] Step 4: Take the modified asphalt from Step 3 and transfer it into a shearing machine. Swell and develop it at 180-200℃ for 30-60 minutes to obtain polypropylene and ethylene-vinyl acetate compound modified asphalt with good storage stability and high and low temperature performance.

[0009] Preferably, the mass ratio of the polypropylene to ethylene-vinyl acetate, desulfurized rubber powder, and matrix asphalt is 3-7:10-40:100.

[0010] Preferably, the mass ratio of polypropylene to ethylene-vinyl acetate is 8:2 to 1:9.

[0011] Most preferably, the mass ratio of polypropylene to ethylene-vinyl acetate is 6:4.

[0012] Preferably, the rotational speed of the Hack matrix rheometer in step one is 40-80 rpm.

[0013] Preferably, the stirring speed in step three is 500-1000 rpm.

[0014] Preferably, the desulfurized rubber powder in step three is 20-60 mesh undesulfurized rubber powder, and the desulfurization degree of the desulfurized rubber powder is 30-60%.

[0015] Preferably, the shearing speed of the shearing machine in step four is 3000-5000 rpm.

[0016] The beneficial effects of this invention are as follows: The combined use of PP and EVA can achieve synergistic effects: PP provides high-temperature stability and strength, while EVA improves flexibility and low-temperature crack resistance. High-temperature melting and calendering improve the swelling and dispersion of PP and EVA in asphalt, forming a good phase interface with the asphalt, increasing the stability of the modified asphalt, and significantly improving the high and low temperature performance of polymer-modified asphalt. This achieves a balanced optimization of the high and low temperature performance of modified asphalt, replacing the use of SBS. This not only reduces dependence on primary petroleum resources and enables the recycling of waste plastics and rubber, reducing energy consumption, but also effectively alleviates the problem of "white pollution." Furthermore, it reduces the construction cost of modified asphalt and improves economic efficiency. Attached Figure Description

[0017] Figure 1 This is a comparison chart of the storage stability of modified asphalt prepared in different embodiments and comparative examples of the present invention.

[0018] Figure 2 This is a comparison chart of the complex modulus of modified asphalt prepared in different embodiments and comparative examples of the present invention.

[0019] Figure 3 This is a phase angle comparison diagram of modified asphalt prepared in different embodiments and comparative examples of the present invention.

[0020] Figure 4 This is a comparison diagram of the phase angle master curves of modified asphalt prepared in different embodiments and comparative examples of the present invention.

[0021] Figure 5 These are scanning electron microscope images of modified asphalt prepared in different embodiments of the present invention.

[0022] Figure 6 These are scanning electron microscope images of the modified asphalt prepared in different comparative proportions according to the present invention. Detailed Implementation

[0023] To make the technical objectives, technical solutions, and technical effects of the present invention easier to understand, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0025] The abbreviations in the following examples and comparative examples represent the following substances: polypropylene (PP), ethylene-vinyl acetate (EVA), desulfurized rubber powder (DCR), and modified bitumen (PEMA).

[0026] Example 1 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh a mixture of PP and EVA in a mass ratio of 8:2, mix them initially, and then transfer them together into a Hacker torque rheometer. Mix them at 40 rpm and 190°C for 15 minutes to obtain a fully mixed polymer.

[0027] Step 2: Transfer the mixed materials from Step 1 into a two-roll mill. The molten mixture is rolled into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized granules.

[0028] Step 3: Take 3 wt% of the PP / EVA mixture from Step 2, which accounts for 30 wt% of the base asphalt, and 40 wt% DCR. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder, with a desulfurization degree of 30-60%. After heating the base asphalt to 150℃, add DCR and PP / EVA polymer. After raising the temperature to 200℃, stir the mixture in a stirrer at 800 rpm for 60 min to obtain the modified asphalt.

[0029] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 200℃ and a shear rate of 4500 rpm, it will swell and develop for 40 minutes to obtain PP / EVA and DCR compound modified asphalt PEMA with good storage stability and high and low temperature performance.

[0030] The performance of the PP / EVA composite material prepared in Example 1 as a substitute for SBS in preparing DCR modified asphalt is shown in Table 1.

[0031] Example 2 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh out a mixture of PP and EVA in a mass ratio of 5:5, mix them initially, and then transfer them into a Hacker torque rheometer. Mix them at 60 rpm and 195°C for 15 minutes to obtain a fully mixed polymer.

[0032] Step 2: Transfer the mixed materials from Step 1 into a two-roll mill. The molten mixture is rolled into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized granules.

[0033] Step 3: Take 7 wt% of the PP / EVA mixture from Step 2, which accounts for 7 wt% of the base asphalt, and 10 wt% DCR. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder, with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and PP / EVA polymer. After raising the temperature to 200 ℃, stir the mixture in a stirrer at 900 rpm for 20 min to obtain the modified asphalt.

[0034] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 190 ℃ and a shear rate of 4500 rpm, it will swell and develop for 50 min to obtain PP / EVA and DCR compound modified asphalt PEMA with good storage stability and high and low temperature performance.

[0035] The performance of the PP / EVA composite material prepared in Example 2 as a substitute for SBS in preparing DCR modified asphalt is shown in Table 1.

[0036] Example 3 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh out a mixture of PP and EVA in a mass ratio of 1:9, mix them initially, and then transfer them into a Hacker torque rheometer. Mix them at 80 rpm and 200 ℃ for 15 minutes to obtain a fully mixed polymer.

[0037] Step 2: Transfer the mixed materials from Step 1 into a two-roll mill. The molten mixture is rolled into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized granules.

[0038] Step 3: Take 5 wt% of the PP / EVA mixture from Step 2, which accounts for 5 wt% of the base asphalt, and 30 wt% DCR. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder, with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and PP / EVA polymer. After raising the temperature to 200 ℃, stir the mixture at 1000 rpm for 40 min to obtain the modified asphalt.

[0039] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 180℃ and a shear rate of 4500 rpm, it will swell and develop for 60 min to obtain PP / EVA and DCR compound modified asphalt PEMA with good storage stability and high and low temperature performance.

[0040] The performance of the PP / EVA composite material prepared in Example 3 as a substitute for SBS in preparing DCR modified asphalt is shown in Table 1.

[0041] Example 4 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh a mixture of PP and EVA in a mass ratio of 6:4, mix them initially, and then transfer them together into a Hacker torque rheometer. Mix them at 60 rpm and 200 ℃ for 15 minutes to obtain a fully mixed polymer.

[0042] Step 2: Transfer the mixed materials from Step 1 into a two-roll mill. The molten mixture is rolled into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized granules.

[0043] Step 3: Take 4 wt% of the PP / EVA mixture from Step 2, which accounts for 4 wt% of the base asphalt, and 20 wt% DCR. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder, with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and PP / EVA polymer. After raising the temperature to 200 ℃, stir the mixture at 1000 rpm for 40 min to obtain the modified asphalt.

[0044] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 180℃ and a shear rate of 4500 rpm, it will swell and develop for 60 min to obtain PP / EVA and DCR compound modified asphalt PEMA with good storage stability and high and low temperature performance.

[0045] The performance of the PP / EVA composite material prepared in Example 4 as a substitute for SBS in preparing DCR modified asphalt is shown in Table 1.

[0046] Comparative Example 1 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Take PP and transfer it into the Hacker torque rheometer, and mix it for 15 minutes at a speed of 30 rpm and a temperature of 200℃.

[0047] Step 2: Transfer the mixture from Step 1 into a two-roll mill. Roll the molten material into sheets in the two-roll mill. After the material cools, transfer it into a granulator and cut it into uniformly sized granules.

[0048] Step 3: Take 1 wt% PP and 20 wt% DCR from the base asphalt in Step 2. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and PP polymer. After raising the temperature to 200 ℃, stir the reaction in a stirrer at 500 rpm for 40 min to obtain the modified asphalt.

[0049] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 180℃ and a shear rate of 3000 rpm, it will swell and develop for 60 minutes to obtain PEMA, a PP and DCR compound modified asphalt with good storage stability and high and low temperature performance.

[0050] The performance of DCR modified asphalt prepared by replacing SBS with PP material prepared in Comparative Example 1 is shown in Table 1.

[0051] Comparative Example 2 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Weigh a mixture of PP and EVA in a mass ratio of 9:1, mix them initially, and then transfer them together into a Hacker torque rheometer. Mix them at 80 rpm and 200 ℃ for 15 minutes to obtain a fully mixed polymer.

[0052] Step 2: Transfer the mixed materials from Step 1 into a two-roll mill. The molten mixture is rolled into sheets in the two-roll mill. After the material cools, it is transferred into a granulator and cut into uniformly sized granules.

[0053] Step 3: Take 4 wt% of the PP / EVA mixture from Step 2, which accounts for 4 wt% of the base asphalt, and 20 wt% DCR. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder, with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and PP / EVA polymer. After raising the temperature to 200 ℃, stir the mixture at 1000 rpm for 40 min to obtain the modified asphalt.

[0054] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 180 ℃ and a shear rate of 4500 rpm, it will swell and develop for 20 min to obtain PP / EVA and DCR compound modified asphalt PEMA with good storage stability and high and low temperature performance.

[0055] The performance of the PP / EVA composite material prepared in Comparative Example 2 as a substitute for SBS in preparing DCR modified asphalt is shown in Table 1.

[0056] Comparative Example 3 A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder includes the following steps: Step 1: Transfer EVA into a Hacker torque rheometer and mix it for 15 minutes at 30 rpm and 200°C.

[0057] Step 2: Transfer the mixed material from Step 1 into a two-roll mill. Roll the molten material into sheets in the two-roll mill. After the material cools, transfer it into a granulator and cut it into uniformly sized granules.

[0058] Step 3: Take 4 wt% EVA and 20 wt% DCR from the base asphalt in Step 2. DCR is used to desulfurize 20-60 mesh undesulfurized rubber powder with a desulfurization degree of 30-60%. After heating the base asphalt to 150 ℃, add DCR and EVA polymer. After raising the temperature to 150 ℃, stir the reaction with a stirrer at 1000 rpm for 40 min to obtain the modified asphalt.

[0059] Step 4: Take the modified asphalt from Step 3 and transfer it into a shear mill. In a high-speed shear mill at 180 ℃ and a shear rate of 4500 rpm, it will swell and develop for 20 min to obtain PEMA, a compound modified asphalt of EVA and DCR with good storage stability and high and low temperature performance.

[0060] The performance of DCR-modified asphalt prepared by replacing SBS with EVA material prepared in Comparative Example 3 is shown in Table 1.

[0061] Comparative Example 4 A method for preparing SBS-modified asphalt includes the following steps: Step 1: Heat the base asphalt to 150 ℃ and then add SBS, which accounts for 3 wt% of the base asphalt.

[0062] Step 2: Stir the modified asphalt from Step 1 in a mixer at a speed of 3000 rpm for 40 minutes.

[0063] Step 3: Transfer the modified asphalt from Step 2 into a shear mill and allow it to swell and develop for 60 minutes in a high-speed shear mill at 180 ℃ and a shear rate of 4500 rpm to obtain SBS modified asphalt SBSMA with good storage stability and high and low temperature performance.

[0064] The properties of the SBS modified asphalt prepared in Comparative Example 4 are shown in Table 1.

[0065] Performance comparison of different modified asphalts The performance test results of the modified asphalt prepared in Examples 1-4 and Comparative Examples 1-4 in this invention are as follows: As shown in Table 1, Figure 1-6As shown, the PP / EVA composite materials prepared in Examples 1, 2, 3, and 4 of the present invention as substitutes for SBS in the preparation of DCR modified asphalt exhibit good high and low temperature performance and storage stability, while the high and low temperature performance and storage stability prepared in Comparative Examples 1, 2, 3, and 4 are poor.

[0066] Compared with the comparative examples, the softening point and elastic recovery ability of the examples were significantly improved. Specifically, Example 4, compared with Comparative Examples 1-4, showed a maximum increase of 23% in softening point and a maximum increase of 5.3% in elastic recovery ability, greatly enhancing the high-temperature stability and elastic recovery ability of the modified asphalt. Figure 1 It can be seen that, compared with the comparative example, the difference in softening points between the upper and lower parts of the softening points in the examples is less than 2.5 ℃, while the difference in softening points between the upper and lower parts of the softening points in the comparative example is greater than 2.5 ℃. The reduced difference in softening points enhances the miscibility between the rubber powder and the asphalt, and improves the storage stability of the modified asphalt. Figures 2-3 It can be seen that the modified asphalt prepared in the examples has a greater complex modulus than that in the comparative examples, and also has a smaller phase angle, exhibiting better resistance to high-temperature deformation. Figure 4 It can be seen that the modified asphalt prepared in the examples has a smaller phase angle and a larger complex modulus across the entire frequency range, and Example 4 has the smallest phase angle, exhibiting the best resistance to temperature changes and low-temperature cracking resistance. Figure 5-6 As can be seen, in the examples, a complex network structure is formed between PP, EVA and asphalt, which greatly enhances the high and low temperature performance of the modified asphalt.

[0067] In summary, the modified asphalt prepared in Example 4 has good resistance to high-temperature deformation and low-temperature cracking, making it the optimal preparation method.

[0068] like Figure 5-6 Scanning electron microscopy (SEM) images show that the PP / EVA blend melts and diffuses under high temperature and mechanical shear in a closed environment, forming a homogeneous molten mixture. The molten mixture is then transferred to an open mill for calendering into sheets, and subsequently to a granulator to be cut into uniformly sized particles. The resulting blend absorbs the light components in the asphalt, swells, and forms a good phase interface with the asphalt, creating a dense network structure within the asphalt. This increases the storage stability of the modified asphalt, enhances its high and low temperature performance, and improves the road construction performance of the composite modified asphalt.

[0069] Therefore, the present invention uses the above-mentioned method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder. The process is simple, and the prepared modified asphalt has good comprehensive performance and high stability. It can be seen that the preparation process of the embodiment of the present invention is more scientific and reasonable.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

[0071] Table 1. Comparison of the four basic properties of different modified asphalts

Claims

1. A method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder, characterized in that: Includes the following steps: Step 1: Weigh the mixture of polypropylene and ethylene-vinyl acetate, mix them initially, and then transfer them together into a Hacker torque rheometer. Mix them at 160-200℃ for 10-15 min to obtain a fully mixed polymer of polypropylene and ethylene-vinyl acetate. Step 2: Transfer the polypropylene and ethylene-vinyl acetate polymer from Step 1 into a two-roll mill. Transfer the molten polymer into the two-roll mill and calender it into sheets. After the material cools, transfer it into a granulator and cut it into uniformly sized polypropylene and ethylene-vinyl acetate polymer granules. Step 3: Take the base asphalt, heat the base asphalt to 150℃, add the desulfurized rubber powder and the polypropylene and ethylene-vinyl acetate polymer particles obtained in Step 2, raise the temperature to 180-200℃, and stir the reaction under a stirrer for 30-60 minutes to initially obtain modified asphalt. Step 4: Take the modified asphalt from Step 3 and transfer it into a shearing machine. Swell and develop it at 180-200℃ for 30-60 minutes to obtain polypropylene and ethylene-vinyl acetate compound modified asphalt with good storage stability and high and low temperature performance.

2. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 1, characterized in that: The mass ratio of the polypropylene to ethylene-vinyl acetate, desulfurized rubber powder, and matrix asphalt is 3-7:10-40:

100.

3. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 2, characterized in that: The mass ratio of the polypropylene to ethylene-vinyl acetate, desulfurized rubber powder, and matrix asphalt is 4:20:

100.

4. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 3, characterized in that: The mass ratio of polypropylene to ethylene-vinyl acetate is 8:2 to 1:

9.

5. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 4, characterized in that: The mass ratio of polypropylene to ethylene-vinyl acetate is 6:

4.

6. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 1, characterized in that: In step one, the rotational speed of the Hack matrix rheometer is 40-80 rpm.

7. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 1, characterized in that: The stirring speed in step three is 500-1000 rpm.

8. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 1, characterized in that: The desulfurized rubber powder in step three is 20-60 mesh undesulfurized rubber powder, and the desulfurization degree of the desulfurized rubber powder is 30-60%.

9. The method for preparing modified asphalt by compounding polypropylene and ethylene-vinyl acetate polymer with desulfurized rubber powder according to claim 1, characterized in that: The shearing speed of the shearing machine in step four is 3000-5000 rpm.

Images