Smoke-inhibited waste rubber powder modified asphalt based on photocatalysis and preparation method thereof

Abstract

This invention provides a photocatalytically modified asphalt based on waste rubber powder and its preparation method. The modified asphalt achieves this by precisely controlling the ratio of waste rubber powder, matrix asphalt, and a smoke suppressant made of graphite-phase carbon nitride. Simultaneously, a segmented gradient temperature-controlled calcination process is employed to prepare graphite-phase carbon nitride with a specific band gap. This ensures good interfacial compatibility among the raw material components, stable system formulation, and uniform and controllable precursor pyrolysis and polymerization reactions. Consequently, the graphite-phase carbon nitride possesses both porous physical adsorption and visible light photocatalytic activity. This allows for efficient adsorption and long-lasting photocatalytic degradation of asphalt fumes while fully preserving the excellent road performance and workability of the waste rubber powder-modified asphalt. The final product is a photocatalytically modified asphalt with simple components, controllable cost, excellent compatibility, long-lasting and stable smoke suppression effect, good process repeatability, and suitability for industrial mass production and widespread application in highway pavement engineering.

Description

Technical Field

[0001] This invention belongs to the field of modified asphalt material preparation technology, specifically involving the resource utilization of waste rubber powder, modified asphalt smoke suppression and photocatalytic composite modification technology, and particularly involving a smoke-suppressing waste rubber powder modified asphalt based on photocatalysis and its preparation method, as well as the application of photocatalytic technology in the smoke suppression modification of waste rubber powder modified asphalt. Background Technology

[0002] Asphalt pavement construction and maintenance are characterized by high resource consumption, high energy consumption, and high carbon emissions. Ordinary petroleum asphalt is highly temperature sensitive, prone to flowing at high temperatures and cracking at low temperatures, making it difficult to meet the requirements for long-term pavement service life. Waste rubber powder modified asphalt is prepared by activating waste tire rubber powder and mixing it with petroleum asphalt and various chemical additives through a high-temperature shearing process. Its performance is similar to that of SBS (styrene-butadiene-styrene block copolymer) modified asphalt, and it can also improve driving comfort and safety, with more significant socio-economic benefits. Therefore, waste rubber powder modified asphalt technology is an important research direction for the green and low-carbon transformation of highway construction.

[0003] However, waste rubber powder modified asphalt releases a large amount of irritating fumes during production and application, containing various harmful substances such as polycyclic aromatic hydrocarbons (PAHs). This not only pollutes the construction site and surrounding environment but also directly endangers the health of construction workers, becoming a key bottleneck restricting the large-scale green application of waste rubber powder modified asphalt.

[0004] To suppress asphalt fumes, smoke suppressants are currently developed based on two main mechanisms of action: one is physical adsorption, which utilizes the large specific surface area and porous structure of the smoke suppressant to adsorb and fix the volatiles in the fumes through physical actions such as van der Waals forces, preventing their escape; the other is chemical degradation, which uses specific active chemical components in the smoke suppressant to react with harmful substances in the fumes through oxidation, catalytic decomposition, and other chemical reactions, transforming them into substances with lower toxicity or smaller molecular weight.

[0005] Specifically, for waste rubber powder modified asphalt systems, existing smoke suppression technologies also revolve around the two categories mentioned above. For example, Chinese patent CN120504973A discloses a odor-neutralizing and smoke-suppressing rubber asphalt made from zinc ricinoleate and organic nano-montmorillonite, and its preparation method, employing a smoke suppression scheme composed of zinc ricinoleate, organic nano-montmorillonite, stabilizers, and furfural extract oil. While this technology can suppress smoke and improve workability to a certain extent, its components are complex and costly, and there may be compatibility issues between various additives, affecting the long-term stability of the asphalt system. Another Chinese patent, CN107892821A, proposes a method of pretreating rubber powder using biomass heavy oil and supplementing it with expanded graphite as a smoke suppressant. This technology mainly relies on the physical adsorption of expanded graphite, and its smoke suppression effect is easily limited by adsorption saturation. Furthermore, the complex pretreatment process may increase energy consumption and uncertainty in the production process, which is not conducive to its engineering application.

[0006] In summary, existing smoke suppression technologies for waste rubber powder modified asphalt either rely on complex multi-component formulations, which present challenges in terms of cost and compatibility; or they mainly depend on physical adsorption, resulting in limited smoke suppression efficiency and a lack of sustainability. Therefore, there is an urgent need to develop a novel smoke suppressant and modification technology with a novel mechanism of action, economical cost, simple process, and highly efficient and long-lasting smoke suppression effect, in order to overcome the environmental bottlenecks in the current promotion and application of waste rubber powder modified asphalt. Summary of the Invention

[0007] In view of this, this application provides a photocatalytically modified asphalt based on waste rubber powder for smoke suppression and its preparation method, which solves the technical problems of existing waste rubber powder modified asphalt smoke suppression technology, such as the high cost and poor compatibility of multi-component compounding, the low adsorption capacity of high specific surface area materials and the lack of long-term effectiveness, and the insufficient research on photocatalytic degradation of flue gas.

[0008] To achieve the above technical objectives, this application adopts the following technical solution: In a first aspect, this application provides a smoke-suppressing waste rubber powder modified asphalt based on photocatalysis, wherein the smoke-suppressing waste rubber powder modified asphalt is made from the following raw materials by mass percentage: 15wt% to 35wt% waste rubber powder, 60wt% to 84wt% base asphalt and 1wt% to 5wt% smoke suppressant; the smoke suppressant is graphitic carbon nitride (g-C3N4) prepared with melamine as a precursor.

[0009] Specifically, waste rubber powder, as the main modifier, can stably improve the elasticity, toughness, and road performance of asphalt within a dosage range of 15wt% to 35wt%. Too low a dosage results in insufficient modification, while too high a dosage easily leads to poor system compatibility and excessive viscosity. 60wt% to 84wt% of base asphalt serves as the continuous phase matrix, suitable for the dispersion and compatibility of waste rubber powder and smoke suppressants, ensuring the overall adhesion, workability, and structural stability of the system. Common smoke suppressant systems are often complex in composition and cumbersome in preparation, and have limited physical adsorption capacity for asphalt fumes; excessive addition can easily lead to increased costs and deterioration of compatibility. Therefore, this invention preferably incorporates 1wt% to 5wt% of g-C3N4, a material that combines porous adsorption characteristics with visible light-responsive photocatalytic activity, achieving efficient and sustained smoke suppression effects with a small addition.

[0010] Preferably, the waste rubber powder is obtained by physically crushing and grinding waste tires.

[0011] Specifically, the above-mentioned waste rubber powder preparation method does not require chemical modification treatment, the process is simple, the raw materials are readily available, and the cost is low. The resulting waste rubber powder has uniform particles and a good pore structure, and has better wetting compatibility with the matrix asphalt, which can give full play to the modification advantages of the rubber's high elasticity and high toughness.

[0012] Preferably, the base asphalt is road petroleum asphalt that meets the requirements of the technical specifications for construction of highway asphalt pavement (JTG 3410-2025).

[0013] Specifically, the aforementioned base asphalt can ensure that the raw material performance indicators are standardized and uniform, and the quality is stable and controllable. It has good compatibility with waste rubber powder and graphite phase carbon nitride smoke suppressant, and can improve the bonding performance, high temperature stability and low temperature crack resistance of the modified asphalt system, making it suitable for conventional road construction technology and engineering technical requirements.

[0014] Preferably, the band gap of the graphitic carbon nitride is 2.0 eV to 3.0 eV.

[0015] Specifically, a band gap of 2.0 eV to 3.0 eV enables graphitic carbon nitride materials to possess suitable visible light response energy levels, which can effectively capture visible light and excite photocatalytic reactions, while also suppressing photogenerated electron-hole recombination, thus ensuring excellent photocatalytic degradation capabilities.

[0016] Secondly, the present invention also provides a method for preparing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis, comprising the following steps: S10 involves heating the base asphalt to a molten and flowing state, adding waste rubber powder, and mixing it by shearing until uniform to obtain waste rubber powder modified asphalt. S20, graphitic carbon nitride is added to waste rubber powder modified asphalt, and the mixture is further sheared and mixed evenly. After heat preservation and development, smoke-suppressing waste rubber powder modified asphalt is obtained.

[0017] Preferably, the shearing and mixing process in step S10 is as follows: the shearing temperature is controlled at 155℃~165℃, and the shearing is first performed at a rate of 3000r / min~4000r / min for 15min~25min, and then at a rate of 4000r / min~5000r / min for 25min~35min.

[0018] Preferably, the shearing and mixing process in step S20 is as follows: the shearing temperature is controlled at 160℃~170℃, and shearing is performed at a rate of 4500r / min~5000r / min for 35min~45min.

[0019] Specifically, this invention first employs segmented temperature-controlled calcination of the melamine precursor in a muffle furnace to ensure the structural stability and photocatalytic activity of the prepared g-C3N4. In the asphalt modification stage, heating the base asphalt to a fluid state facilitates its uniform mixing with waste rubber powder and smoke suppressant. Under shear conditions of 155℃–170℃, the system maintains good fluidity, not only meeting shear requirements but also promoting the swelling and dispersion of waste rubber powder, avoiding performance fluctuations caused by uneven stirring. By controlling the shear rate and time, uniform distribution of each component can be ensured, ultimately yielding a stable smoke-suppressant waste rubber powder modified asphalt.

[0020] Preferably, the method for preparing graphitic carbon nitride in step S20 includes: First, melamine is ground and placed in a crucible, then heated in a muffle furnace at a first heating rate to 295℃~305℃, and held for 1.5h~2.5h to obtain an intermediate. Subsequently, the intermediate was heated to 545℃~555℃ at a second heating rate, held at that temperature for 3h~5h, cooled, and then ground to obtain graphitic carbon nitride.

[0021] Preferably, the first heating rate is 3℃ / min to 7℃ / min, and the second heating rate is 1℃ / min to 4℃ / min.

[0022] Specifically, this preparation method, through two-stage gradient calcination and strict limitation of process parameter range, enables the melamine precursor to achieve stable pyrolysis, gradual polymerization and ordered crystal phase growth, avoiding local agglomeration, excessive structural defects or incomplete pyrolysis caused by excessively rapid heating, and also preventing problems such as increased energy consumption and excessively long preparation cycle caused by excessively slow heating.

[0023] Preferably, the melamine has a moisture content of ≤0.2wt% and a solid content of ≥99.5wt%.

[0024] Specifically, the aforementioned low-water-content melamine can effectively avoid problems such as water vapor disturbance, uneven heating, foaming and agglomeration, and crystal structure defects that occur during calcination due to excessively high water content in the raw materials, thus ensuring that the melamine pyrolysis polymerization reaction proceeds uniformly and stably.

[0025] The beneficial effects of this application are as follows: This invention provides a photocatalytically modified asphalt based on waste rubber powder and its preparation method. The aforementioned smoke-suppressing waste rubber powder modified asphalt achieves a precise ratio of waste rubber powder, matrix asphalt, and a smoke suppressant made of graphite-phase carbon nitride material. Simultaneously, a segmented gradient temperature-controlled calcination process is used to prepare graphite-phase carbon nitride with a specific band gap, ensuring good interfacial compatibility among the raw material components, stable system compatibility, and uniform and controllable precursor pyrolysis and polymerization reactions. This results in graphite-phase carbon nitride possessing both porous physical adsorption and visible light photocatalytic activity, effectively overcoming the shortcomings of traditional smoke suppression technologies, such as complex component formulation, high cost, limited adsorption capacity, and lack of long-term smoke suppression. Furthermore, while fully preserving the excellent road performance and workability of waste rubber powder modified asphalt, it achieves efficient adsorption and long-term photocatalytic degradation of asphalt fumes, ultimately yielding a photocatalytically modified asphalt with simple components, controllable cost, excellent compatibility, long-lasting and stable smoke suppression effect, good process repeatability, and suitability for industrial mass production and promotion in highway pavement engineering. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the preparation method of smoke-suppressing waste rubber powder modified asphalt based on photocatalysis in Example 1; Figure 2 Comparison of smoke concentration in smoke-suppressing waste rubber powder-modified asphalt under light and dark conditions; Figure 3 A comparison of H2S concentrations in smoke-suppressing waste rubber powder-modified asphalt under light and dark conditions. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] To address the shortcomings of existing technologies, this invention provides a photocatalytically modified asphalt based on waste rubber powder for smoke suppression and its preparation method. It uses graphitic carbon nitride (g-C3N4) prepared with melamine as a precursor as a dedicated smoke suppressant to construct a synergistic smoke suppressant composite material system that can simultaneously achieve physical adsorption and photocatalytic degradation. Not only are the raw materials widely available and inexpensive, but the overall preparation process is also simple and easy to implement. Furthermore, it possesses excellent and long-lasting smoke suppressant performance, effectively solving various problems existing in current smoke suppressant technologies.

[0029] The preparation method of smoke-suppressing waste rubber powder modified asphalt based on photocatalysis provided by this invention has the following outstanding advantages: (1) The raw material cost is low, the preparation process is simple and easy to implement, and it is convenient for large-scale production and application, thus having good economic benefits; (2) The asphalt material obtained can significantly suppress the emission of harmful fumes (especially sulfides) during construction through the synergistic effect of physical adsorption and photocatalytic degradation of g-C3N4, reduce the impact on the environment and human health, and promote the green and efficient utilization of waste rubber powder in road engineering.

[0030] The present invention will be further described below through specific embodiments and comparative examples.

[0031] The relevant properties of the base bitumen used in the following examples are shown in Table 1: Table 1 Basic performance indicators of base asphalt

[0032] The main components of the waste adhesive powder used in the following examples are shown in Table 2: Table 2 Main Chemical Components of Waste Rubber Powder

[0033] Example 1: Example 1 provides a photocatalytic smoke-suppressing waste rubber powder modified asphalt, which is made from the following raw materials by mass percentage: 20wt% waste rubber powder, 79wt% base asphalt and 1wt% smoke suppressant; the smoke suppressant is graphitic carbon nitride (g-C3N4) prepared with melamine as a precursor.

[0034] In Example 1, the waste rubber powder was obtained by physically crushing and grinding waste tires, with a particle size of 60 mesh; the base asphalt refers to road petroleum asphalt that meets the technical requirements of the "Technical Specification for Construction of Highway Asphalt Pavement" (JTG 3410-2025); the smoke suppressant is graphitic carbon nitride (g-C3N4) prepared with melamine as a precursor; the band gap of graphitic carbon nitride is 2.0 eV to 3.0 eV.

[0035] Please see Figure 1 Example 1 also provides a method for preparing and testing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis, specifically including the following steps: Step (1): First, take 50g of melamine (moisture content ≤0.2wt%, solid content ≥99.5wt%), grind it and place it in a crucible. Heat it to 300℃ using a muffle furnace at a first heating rate of 5℃ / min and hold it for 2h to obtain an intermediate. Then, continue to calcine the obtained intermediate at a second heating rate of 2℃ / min to 550℃ and hold it for 4h. After cooling and grinding, g-C3N4 powder is obtained.

[0036] Step (2): Heat the base asphalt to a molten and flowing state, add waste rubber powder, and shear at 3500 r / min for 20 min at 160℃, and then shear at 4000 r / min for 30 min to obtain waste rubber powder modified asphalt. Step (3): Add 1wt% smoke suppressant, set the shear temperature to 165℃, the shear rate to 4500r / min, and shear for 40min to obtain smoke suppressant waste rubber powder modified asphalt; Step (4): Under light conditions, use a portable flue gas analyzer to test the VOCs (organic waste gas) and H2S emissions of the obtained waste rubber powder modified asphalt.

[0037] Example 2: The difference from Example 1 is that the mass percentage of the base asphalt is adjusted to 77wt%, the amount of smoke suppressant added is set to 3wt%, and other conditions are the same as in Example 1.

[0038] Example 3: The difference from Example 1 is that the mass percentage of the base asphalt is adjusted to 75 wt%, the amount of smoke suppressant added is set to 5 wt%, and other conditions are the same as in Example 1.

[0039] Comparative Example 1: The only difference from Example 1 is that no smoke suppressant is added, the base asphalt mass ratio is 80wt%, and other conditions are the same as in Example 1.

[0040] Comparative Example 2: The only difference from Example 1 is that no smoke suppressant was added, the matrix asphalt mass ratio was 80wt%, and the emissions of VOCs and H2S were tested using a portable flue gas analyzer under dark conditions. Other conditions were the same as in Example 1.

[0041] Comparative Example 3: The difference from Example 1 is that the emissions of VOCs and H2S were tested using a portable flue gas analyzer under dark conditions, while other conditions were the same as in Example 1.

[0042] Comparative Example 4: The difference from Example 2 is that the emissions of VOCs and H2S were tested using a portable flue gas analyzer under dark conditions, while other conditions were the same as in Example 2.

[0043] Comparative Example 5: The difference from Example 3 is that the emissions of VOCs and H2S were tested using a portable flue gas analyzer under dark conditions, while other conditions were the same as in Example 3.

[0044] Smoke test: The VOCs and H2S emissions of Examples 1-3 and Comparative Examples 1-5 were tested using a portable flue gas analyzer. The effects of different smoke suppressant dosages and different light conditions on the VOCs and H2S emissions of waste rubber powder modified asphalt were compared. The experimental results are as follows: Figure 2 , Figure 3 As shown.

[0045] Depend on Figure 2 It can be seen that the VOC emissions of Comparative Examples 1-2 (0% g-C3N4 content) were all 672 ppm under both dark and light conditions, with no significant difference; the emissions of Comparative Examples 3 (1% g-C3N4 content, dark), 4 (3% g-C3N4 content, dark), and 5 (5% g-C3N4 content, dark) were 443 ppm, 223 ppm, and 125 ppm, respectively, showing a gradient decrease with increasing content, reflecting the physical adsorption and smoke suppression effect of g-C3N4; while the emissions of the Example The emissions of Example 1 (1% g-C3N4 dosage, light irradiation), Example 2 (3% g-C3N4 dosage, light irradiation), and Example 3 (5% g-C3N4 dosage, light irradiation) were further reduced to 398 ppm, 163 ppm, and 61 ppm, respectively. Compared with the comparative examples with the same dosage, the emissions were significantly reduced, which proves that the photocatalytic effect of g-C3N4 under light irradiation can synergistically achieve stronger smoke suppression through physical adsorption. Moreover, this synergistic effect becomes more and more obvious with the increase of dosage. A significant reduction in VOCs emissions was achieved at a g-C3N4 dosage of 5%.

[0046] Depend on Figure 3 It can be seen that the H2S emissions of Comparative Example 1 and Comparative Example 2 (g-C3N4 dosage of 0%) were both 42.1 ppm under both light and dark conditions, with no significant difference. As the g-C3N4 dosage increased, the H2S emissions of Comparative Example 3, Comparative Example 4, and Comparative Example 5 under dark conditions decreased to 21.9 ppm, 10.2 ppm, and 6.0 ppm, respectively, demonstrating the physical adsorption and smoke suppression effect of g-C3N4. Under light conditions, the emissions of Example 1, Example 2, and Example 3 further decreased to 19.7 ppm, 8.8 ppm, and 3.6 ppm, respectively, which were significantly lower than those of the comparative examples with the same dosage. This indicates that the photocatalytic effect activated by light can synergistically reduce H2S emissions with physical adsorption, and the synergistic smoke suppression effect is enhanced with the increase of g-C3N4 dosage, fully verifying the high efficiency of the H2S smoke suppression performance of the system of the present invention.

[0047] therefore, Figure 2 and Figure 3Experimental results show that: Comparative Examples 1-2 (0% g-C3N4 doping) showed no difference in VOCs and H2S emissions under dark and light conditions; as the g-C3N4 doping content increased, the VOCs and H2S emissions of Comparative Examples 3-5 under dark conditions decreased in a gradient, proving that g-C3N4 has a physical adsorption smoke suppression effect; while the emissions of Examples 1-3 under light conditions were significantly lower than those of the comparative examples with the same doping content, and the reduction became more and more obvious with the increase of doping content, indicating that visible light can activate the photocatalytic activity of g-C3N4, forming a synergistic smoke suppression effect with physical adsorption, further enhancing the reduction effect of VOCs and H2S, verifying that the present invention has the dual smoke suppression advantages of physical adsorption and photocatalytic degradation.

[0048] In summary, unlike existing technologies, the photocatalytically modified smoke-suppressing waste rubber powder asphalt and its preparation method provided by this invention have the following advantages: (1) Physicochemical Synergistic High-Efficiency Smoke Suppression: This invention is the first to apply g-C3N4 with photocatalytic properties to smoke suppression of waste rubber powder modified asphalt. g-C3N4 has both the physical adsorption capacity of porous structure and the photocatalytic oxidation activity responsive to visible light, which can achieve the synergistic effect of physical adsorption and chemical degradation, and achieve efficient and continuous suppression and decomposition of harmful components such as polycyclic aromatic hydrocarbons and sulfur-containing compounds in asphalt smoke.

[0049] (2) Economical raw materials and simple process: Melamine, the precursor of smoke suppressant, is widely available and inexpensive, and its preparation process is simple and easy to scale up. The modification steps of introducing it into the asphalt system are simple, without the need for complex pretreatment or the addition of multiple additives, and it is easy to implement in the existing production process.

[0050] (3) Simultaneous improvement of road performance: The addition of g-C3N4 not only effectively suppresses smoke, but also improves the high-temperature performance of waste rubber powder modified asphalt, such as increasing the softening point and enhancing its resistance to rutting, thus achieving a dual improvement in environmental protection and road performance.

[0051] (4) Significant environmental benefits: This invention significantly reduces the emissions of harmful fumes, especially characteristic pollutants such as sulfides, during the production, high-temperature mixing and construction of waste rubber powder modified asphalt, thereby mitigating the harm to the environment and construction personnel, and providing a practical solution for the large-scale and green application of waste tire rubber powder in road engineering.

[0052] This invention uses melamine as a raw material to prepare g-C3N4 as a smoke suppressant. The raw materials are economical and low-cost, the preparation process is simple, and it has a good modification effect on asphalt, increasing the softening point of waste rubber powder modified asphalt and improving its high-temperature performance. The smoke-suppressing waste rubber powder modified asphalt obtained by this invention can effectively suppress the smoke from waste rubber powder modified asphalt through the combined action of physical adsorption and photocatalytic degradation, significantly reducing the emission of harmful smoke, especially sulfides, from waste rubber powder modified asphalt, thus providing an effective method for the environmentally friendly utilization of waste rubber powder.

[0053] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A photocatalytically modified asphalt based on smoke-suppressing waste rubber powder, characterized in that, The smoke-suppressing waste rubber powder modified asphalt is made from the following raw materials by mass percentage: 15wt% to 35wt% waste rubber powder, 60wt% to 84wt% base asphalt, and 1wt% to 5wt% smoke suppressant; the smoke suppressant is graphitic carbon nitride prepared with melamine as a precursor.

2. The photocatalytically modified asphalt based on smoke-suppressing waste rubber powder according to claim 1, characterized in that, The waste rubber powder is produced by physically crushing and grinding waste tires.

3. The photocatalytically modified asphalt based on smoke-suppressing waste rubber powder according to claim 1, characterized in that, The base asphalt is road petroleum asphalt that meets the technical specifications for highway asphalt pavement construction.

4. The photocatalytically modified asphalt based on smoke-suppressing waste rubber powder according to claim 1, characterized in that, The band gap of the graphitic carbon nitride is 2.0 eV to 3.0 eV.

5. A method for preparing smoke-suppressing waste rubber powder modified asphalt according to any one of claims 1 to 4, characterized in that, Includes the following steps: S10, the base asphalt is heated to a molten and flowing state, the waste rubber powder is added, and the mixture is sheared and mixed until uniform to obtain waste rubber powder modified asphalt; S20, the graphite phase carbon nitride is added to the waste rubber powder modified asphalt, and the mixture is further sheared and mixed evenly. Then, it is heat-preserved and developed to obtain the smoke-suppressing waste rubber powder modified asphalt based on photocatalysis.

6. The preparation method of smoke-suppressing waste rubber powder modified asphalt based on photocatalysis according to claim 5, characterized in that, The shearing and mixing process in step S10 is as follows: the shearing temperature is controlled at 155℃~165℃, and the shearing is first performed at a rate of 3000r / min~4000r / min for 15min~25min, and then at a rate of 4000r / min~5000r / min for 25min~35min.

7. The method for preparing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis according to claim 5, characterized in that, The shearing and mixing process in step S20 is as follows: the shearing temperature is controlled at 160℃~170℃, and shearing is performed at a rate of 4500r / min~5000r / min for 35min~45min.

8. The method for preparing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis according to claim 5, characterized in that, The method for preparing the graphitic carbon nitride in step S20 includes: First, melamine is ground and placed in a crucible, then heated in a muffle furnace at a first heating rate to 295℃~305℃, and held for 1.5h~2.5h to obtain an intermediate. Subsequently, the intermediate is heated to 545°C to 555°C at a second heating rate, held at that temperature for 3 to 5 hours, cooled, and then ground to obtain the graphitic carbon nitride.

9. The method for preparing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis according to claim 8, characterized in that, The first heating rate is 3℃ / min to 7℃ / min, and the second heating rate is 1℃ / min to 4℃ / min.

10. The method for preparing smoke-suppressing waste rubber powder modified asphalt based on photocatalysis according to claim 8, characterized in that, The melamine has a moisture content of ≤0.2wt% and a solid content of ≥99.5wt%.

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