Asphalt modifier, method for modifying asphalt through cooperation of organic montmorillonite, waste plastic and nucleating agent, and modified asphalt

Abstract

The invention discloses a method for modifying asphalt through cooperation of an asphalt modifier, montmorillonite, waste plastic and a nucleating agent and the modified asphalt, and relates to the technical field of asphalt materials for road engineering. The asphalt modifier is prepared by blending and extruding waste plastic, a nucleating agent and organic montmorillonite as raw materials; the main component of the waste plastic is PE, and the content of PE in the waste plastic is 68.9-78.8%; the weight ratio of the organic montmorillonite to the PE is 1: (1.5-2.5); the weight ratio of the nucleating agent to the PE is 1: (2-6). The mixing amount of the asphalt modifier in the matrix asphalt is 4-7wt% in terms of PE (polyethylene). The softening point of the modified asphalt can be improved compared with that before modification; after the PE is nucleated, crystal balls can be better inserted into the layered structure of the organic montmorillonite, so that the storage stability of the PE in the matrix asphalt is effectively improved; the cost of the modified asphalt can be reduced while harmless and resource utilization of the waste plastic can be realized, and double benefits of environment and economy are realized.

Description

Technical Field

[0001] This invention relates to the field of asphalt materials technology for road engineering, specifically to a method and modified asphalt using an asphalt modifier, montmorillonite, waste plastics, and nucleating agents. Background Technology

[0002] Over 90% of my country's expressways are asphalt pavements. Currently, asphalt pavements are designed for a lifespan of 15 years; however, under heavy traffic loads and extreme weather conditions, these pavements are prone to damage and other problems. Statistics show that over 70% of expressways require major or medium-scale repairs after approximately 10 years of service, resulting in significant resource consumption and making sustainability difficult.

[0003] Currently, styrene-butadiene-styrene block copolymer (SBS) modified asphalt is the most widely used high-performance asphalt modification method in road engineering. However, in recent years, the market supply of specific grades of SBS materials suitable for asphalt modification has been consistently tight, with demand exceeding supply, leading to a significant price increase and substantially raising the production cost of modified asphalt. On the other hand, with the development of the social economy and industrialization, a large number of plastic products are produced and used every year. Although these plastic products bring great convenience to people's lives, waste plastics are difficult to degrade effectively, putting serious pressure on the natural ecological environment, polluting soil and water systems, and leading to serious waste of resources, increasingly exacerbating the contradiction between environmental protection and economic development. At the same time, improper recycling and disposal of waste plastics also causes serious "white pollution." The recycling of plastic products is mainly divided into two categories: energy recovery and material recovery. Among them, (1) the energy recovery process is simple, and heat energy is provided by incineration, but a large amount of toxic and harmful gases and particulate matter are generated during the incineration process, and a large amount of carbon dioxide is emitted; (2) material recycling is divided into physical recycling and chemical recycling, and most waste plastic products can no longer be used for food grade, because food grade plastic recycling has strict requirements on the appearance and color of waste plastics, and generally requires pure color waste plastics. Waste plastic products not only pollute the environment, but also occupy a large amount of land. Road construction has a strong capacity to absorb these wastes. Converting waste plastics into high value-added road materials and realizing their resource recycling has become a key issue of widespread concern around the world, and also has great environmental and economic significance.

[0004] For example, Chinese patent document CN102337035A provides a scheme for modifying asphalt using waste plastics, specifically disclosing a waste plastic-modified asphalt and its preparation method. The waste plastic-modified asphalt is made from a mixture of base asphalt, waste plastics, compatibilizers, and inorganic fillers. Based on 100 parts by weight of the base asphalt, the waste plastics are 4-12 parts by weight, the compatibilizers are 2-5 parts by weight, and the inorganic fillers are 2-20 parts by weight. This technical solution points out that waste low-density polyethylene (LDPE) has poor compatibility with base asphalt, requiring the addition of inorganic substances such as talc and carbon black to balance the density of waste LDPE and waste polypropylene with the base asphalt, thereby improving compatibility. However, the need to add talc, carbon black, compatibilizers, and other additives increases costs, resulting in low acceptability in practical engineering. Chinese patent document CN119081430A discloses a compatibility-stabilized recycled asphalt material from waste plastics and its preparation method. The technical solution involves using polyethylene (PE) and other plastics with specific melt flow index (10-20 g / 10min) and particle size (200-400 mesh) as modifiers, combined with polyphosphoric acid, dioctyl maleate / aromatic oil / epoxidized soybean oil, and other composite solubilizers, as well as targeted antioxidants, working synergistically. The composite modified asphalt comprises: 80-120 parts of base asphalt, 1-7 parts of plastic, 1-15 parts of composite solubilizer, and 0.08-1.5 parts of antioxidant. While this technical solution improves the compatibility between PE and asphalt and inhibits phase separation, it still faces potential challenges such as the industrialization difficulties of ultrafine waste plastic pulverization, the compatibility and synergistic stability risks of the composite solubilizer itself, and the limited improvement effect on the compatibility of high-crystallinity HDPE. Chinese patent document CN1025742C discloses a method for manufacturing a synthetic material-modified asphalt binder for building materials, particularly paving materials, and the product thereof. This technical solution mainly utilizes polymers such as styrene-butadiene-styrene block copolymer (SBS), high-density polyethylene (PE), and low-density polypropylene (LDPP) to modify asphalt. However, the modified asphalt product prepared by this method suffers from poor storage stability: specifically, after standing at 160°C for 24 hours and then cooling, the modified system exhibits phase separation and stratification.

[0005] In summary, to achieve high-value resource utilization of waste plastics, it is necessary to effectively address issues such as poor interfacial compatibility and easy segregation between plastics and asphalt during the modification process, and improve the storage stability of modified asphalt. This invention aims to provide a scheme for preparing modified asphalt using montmorillonite in conjunction with waste plastics and nucleating agents, thereby solving the problems existing in the prior art. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method and modified asphalt using an asphalt modifier, montmorillonite, waste plastics, and a nucleating agent. The aim is to solve the problems of poor interfacial compatibility and easy segregation between plastics and asphalt in the existing process of modifying asphalt from waste plastics, thereby achieving the harmless and high-value resource utilization of waste plastics while effectively improving the storage stability of the base asphalt.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an asphalt modifier, which is prepared by co-extrusion using waste plastics, nucleating agents, and organomontmorillonite as raw materials; wherein the main component of the waste plastics is PE, and the PE content in the waste plastics is 68.9% to 78.8%;

[0009] The weight ratio of organomontmorillonite to PE is 1:1.5~2.5; the weight ratio of nucleating agent to PE is 1:2~6.

[0010] Furthermore, the amount of the asphalt modifier in the base asphalt is 4wt%~7wt% based on PE.

[0011] Furthermore, the nucleating agent is an organic nucleating agent or an inorganic nucleating agent.

[0012] Preferably, the organic nucleating agent is any one of aluminum stearate, calcium stearate, or organophosphate nucleating agents.

[0013] Preferably, the inorganic nucleating agent is any one of CaCO3, talc, and silicon dioxide.

[0014] Furthermore, the preparation method of the asphalt modifier is as follows:

[0015] (1) The recycled waste plastic is rinsed to remove surface stains and dried, and then crushed, ground and screened to obtain waste plastic granules; preferably, the particle size of the plastic granules is ≤5mm;

[0016] (2) The waste plastic particles obtained in (1) are blended with nucleating agent and organomontmorillonite according to a preset ratio and extruded to obtain the asphalt modifier; preferably, the particle size of the asphalt modifier is controlled to be ≤220 mesh.

[0017] Furthermore, in (1), the rinsing time is 2h~6h.

[0018] Furthermore, the drying conditions in (1) are: drying at 75℃~90℃ for 2h~4h.

[0019] Secondly, the present invention provides a method for modifying asphalt using organomontmorillonite in conjunction with waste plastics and nucleating agents, comprising the following steps:

[0020] S1. Melt the base asphalt by heating, then add the asphalt modifier while controlling the temperature at 160~170℃, stirring constantly to prevent agglomeration; the amount of the asphalt modifier in the base asphalt is 4wt%~7wt% (based on PE).

[0021] S2. Next, a disperser is used to perform preliminary dispersion and stirring at a rate of 200~300 rad / min.

[0022] S3. After the initial dispersion and mixing is completed, control the shear rate to 4500~5000r / min and perform high-speed shearing on the mixture for 45~60min, while controlling the temperature at 170~180℃.

[0023] S4. Disperse and stir at a high speed of 300~450 rad / min to obtain the final product.

[0024] Furthermore, in S1, the base bitumen is heated at 140~150℃ for 30~35 minutes to melt it.

[0025] Furthermore, the initial dispersion and stirring time of S2 is controlled at 10~15 min.

[0026] Furthermore, the high-speed dispersion and stirring time of S4 is controlled at 15~20 min, and the temperature is controlled at 170~185℃.

[0027] Thirdly, the present invention also provides modified asphalt prepared by the method described above for modifying asphalt with organomontmorillonite in conjunction with waste plastics and nucleating agents.

[0028] The present invention has the following beneficial effects:

[0029] The asphalt modifier provided by this invention is prepared using waste plastics, nucleating agents, and organomontmorillonite as raw materials. Compared with the prior art, this invention has the following technical advantages:

[0030] This invention employs a low-carbon asphalt modifier, prepared by twin-screw extrusion of waste plastics, nucleating agents (including organic or inorganic nucleating agents), and organomontmorillonite, to modify ordinary petroleum asphalt. The modified asphalt exhibits a higher softening point and significantly improved storage stability compared to the unmodified form. This demonstrates that the method of modifying asphalt using organomontmorillonite in synergy with waste plastics and nucleating agents effectively improves the storage stability of ordinary petroleum asphalt, thereby producing a green and sustainable asphalt binder. Furthermore, using waste plastics as raw materials to prepare the asphalt modifier addresses the environmental problems caused by "white pollution" resulting from the incineration and accumulation of waste plastics; it enables the harmless and resource-based utilization of waste plastics, while also reducing the cost of modified asphalt, achieving both environmental and economic benefits.

[0031] The low-carbon asphalt modifier provided by this invention uses waste plastics as the main raw material, with PE as its main component. During the modification process, PE, as a high-molecular polymer, exists in the matrix asphalt in the form of a polymer chain. This provides the possibility for the formation of its network structure and the adsorption of light components (such as aromatic components) in the matrix asphalt. The adsorption effect reduces the relative content of free light components in the modified asphalt, thereby improving the high-temperature performance of the asphalt. Simultaneously, the crystallization behavior of the plastic modified by melt blending with organic or inorganic nucleating agents via a twin-screw extruder is significantly optimized. Specifically, the nucleating agent can induce PE molecule nucleation, significantly increasing the overall crystal density of the plastic phase, thus playing a role in balancing density. This optimization of the microstructure also lays a key foundation for the synergistic modification effect with layered silicate organomontmorillonite. The organomontmorillonite in the asphalt modifier provided by this invention has a typical layered structure. The spherulites formed after nucleation by the nucleating agent, transitioning from disorder to order, have better diffusion capabilities, making it easier to intercalate into the interlayer gaps of the organomontmorillonite. This successful intercalation process enables the creation of a more stable composite structure between the plastic phase and the organomontmorillonite. This structure effectively restricts the macroscopic migration and aggregation of the plastic phase in the asphalt matrix, thereby fundamentally and significantly suppressing the common plastic segregation phenomenon in modified asphalt systems, ultimately endowing the composite material with excellent and long-term stable properties.

[0032] In summary, the present invention provides a solution for modifying asphalt with montmorillonite in synergy with waste plastics and nucleating agents, which can solve the problems of poor interfacial compatibility and easy segregation between plastics and asphalt in the process of modifying asphalt with waste plastics in the prior art. While realizing the harmless and high-value resource utilization of waste plastics, it effectively improves the storage stability of the base asphalt. It has the characteristics of simple preparation process, low cost and broad application prospects. Attached Figure Description

[0033] Figure 1 This is a comparison diagram of the storage stability of modified asphalt or asphalt in the embodiments and comparative examples of the present invention. From left to right, the diagrams correspond to: pure PE modified asphalt of Comparative Example 1; modified asphalt of Comparative Example 2 (PE + organomontmorillonite (OMMT)); modified asphalt of Comparative Example 3 (PE:aluminum stearate = 4:1); modified asphalt of Example 11 (PE:aluminum stearate = 4:1 + OMMT); modified asphalt of Comparative Example 4 (PE:CaCO3 = 5:1); and modified asphalt of Example 16 (PE:CaCO3 = 5:1 + OMMT).

[0034] Figure 2These are XRD patterns of the modified asphalt or asphalt in various embodiments and comparisons of the present invention. From bottom to top, the curves correspond to: organomontmorillonite; Comparative Example 2 (PE + organomontmorillonite (OMMT)) modified asphalt; Example 12 (PE:aluminum stearate = 6:1 + OMMT) modified asphalt; Example 13 (PE:aluminum stearate = 5:1 + OMMT) modified asphalt; Example 11 (PE:aluminum stearate = 4:1 + OMMT) modified asphalt; Example 17 (PE:CaCO3 = 6:1 + OMMT) modified asphalt; and Example 16 (PE:CaCO3 = 5:1 + OMMT) modified asphalt.

[0035] Figure 3 The images show fluorescence micrographs of the nucleation of modifiers in various embodiments and comparisons of the present invention, wherein: 3(a) is PE-modified asphalt of Comparative Example 1; 3(b) is PE-modified asphalt of Comparative Example 2 (PE + organomontmorillonite (OMMT)); 3(c) is PE-modified asphalt of Example 12 (PE:aluminum stearate = 6:1 + OMMT); 3(d) is PE-modified asphalt of Example 13 (PE:aluminum stearate = 5:1 + OMMT); 3(e) is PE-modified asphalt of Example 11 (PE:aluminum stearate = 4:1 + OMMT); 3(f) is PE-modified asphalt of Example 17 (PE:CaCO3 = 6:1 + OMMT); and 3(g) is PE-modified asphalt of Example 16 (PE:CaCO3 = 5:1 + OMMT). Detailed Implementation

[0036] As used in this article:

[0037] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0038] When a parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1~5” is disclosed, the described range should be interpreted as including ranges “1~4”, “1~3”, “1~2”, “1~2 and 4~5”, “1~3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In these embodiments, unless otherwise specified, portions and percentages are expressed by mass.

[0039] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] This invention provides an asphalt modifier, which is produced by co-extrusion of waste plastics, nucleating agents, and organomontmorillonite as raw materials. The main component of the waste plastics is PE, typically containing 68.9% to 78.8%. The weight ratio of organomontmorillonite to PE is 1:1.5 to 2.5; the weight ratio of nucleating agent to PE is 1:2 to 6. The dosage of the asphalt modifier in the base asphalt is 4wt% to 7wt% based on PE, preferably 5wt% based on PE. The following specific embodiment illustrates this by controlling the PE dosage to 5wt%.

[0042] In the asphalt modifier provided by this invention, the nucleating agent is an organic nucleating agent or an inorganic nucleating agent. The organic nucleating agent is any one of aluminum stearate, calcium stearate, or organophosphate nucleating agents. The inorganic nucleating agent is any one of CaCO3, talc, or silica.

[0043] Specifically, the weight ratio of organomontmorillonite to PE includes, but is not limited to, 1:1.5, 1:2, and 1:2.5; preferably, it is 1:2. The following specific embodiments are illustrated using 1:2 as an example.

[0044] The weight ratio of nucleating agent to PE includes, but is not limited to, 1:2, 1:3, 1:4, 1:5, and 1:6. The preferred organic nucleating agent is aluminum stearate, and the preferred inorganic nucleating agent is CaCO3.

[0045] The following detailed explanation uses specific examples:

[0046] Example 1 (Preparation Example of Asphalt Modifier)

[0047] This embodiment provides a method for preparing the asphalt modifier, specifically including the following steps:

[0048] (1) The waste plastics collected from the waste recycling plant are rinsed until surface stains are removed; the rinsing time is generally 2-6 hours; in this preferred embodiment, the rinsing time is 5 hours. Then the rinsed waste plastics are placed in an oven, and the drying temperature is generally controlled at 75℃-90℃ for 2-4 hours; in this preferred embodiment, the drying temperature is controlled at 80℃ for 3 hours. After that, the dried waste plastics are crushed and ground using a turbine crusher, and then screened to obtain plastic particles with a particle size of less than or equal to 5 mm.

[0049] Typically, recycled waste plastics mainly consist of PE. Measurements show that the batch of waste plastics used in this embodiment contains 72.5% PE. Those skilled in the art will understand that, in addition to the main component PE, waste plastic materials also contain PET, small amounts of molding aids, etc.

[0050] (2) Add a nucleating agent and organomontmorillonite to the plastic granules obtained in (1), and then co-extrude them through a twin-screw extruder to obtain a low-carbon asphalt modifier. The particle size of the asphalt modifier is ≤220 mesh. In this embodiment, an organic nucleating agent is selected, specifically aluminum stearate, with a weight ratio of aluminum stearate to PE in the waste plastic of 1:4; BS-1C organomontmorillonite is selected, with a weight ratio of organomontmorillonite to PE in the waste plastic of 1:2. This is designated as modifier No. 1.

[0051] Similarly, Examples 2-5 also used the organic nucleating agent aluminum stearate, and the preparation method was the same as in Example 1. The difference between Examples 2-5 and Example 1 was that the weight ratio of aluminum stearate to PE in waste plastic was 1:6, 1:5, 1:3, and 1:2, respectively. The asphalt modifiers obtained were designated as Modifier No. 2, No. 3, No. 4, and No. 5, respectively.

[0052] Examples 6-10 used the inorganic nucleating agent CaCO3, and the preparation method was the same as in Example 1. The difference between Examples 6-10 and Example 1 was that the weight ratio of CaCO3 to PE in waste plastic was 1:5, 1:6, 1:4, 1:3, and 1:2, respectively. The resulting asphalt modifiers were designated as Modifier No. 6, No. 7, No. 8, No. 9, and No. 10, respectively.

[0053] Example 11 (Example of modified bitumen preparation)

[0054] This embodiment provides a method for preparing modified asphalt, specifically including the following steps:

[0055] S1 and 70# base asphalt were heated at 145℃ for 30 minutes to melt them. Then, modifier No. 1, prepared as described in Example 1, was added. The dosage of modifier No. 1 was controlled based on PE, with the PE dosage controlled at 5%. The temperature was controlled at 175℃, and the mixture was manually stirred for 5 minutes.

[0056] S2. After manual stirring, use a disperser to control the stirring rate at 200~300 rad / min for preliminary dispersion and stirring for 10 minutes;

[0057] S3. After initial mixing, the mixture is subjected to high-speed shearing for 45 minutes, with the shearing rate controlled at 4500 r / min and the temperature controlled at 175℃.

[0058] S4. Further disperse the mixture by high-speed stirring at a rate of 350 rad / min for 15 min, and at a temperature of 180℃ to obtain the final product.

[0059] Similarly, the preparation methods of Examples 12-20 are the same as those of Example 11. The difference between Examples 12 and 20 is that the asphalt modifiers added in step S1 are modifiers No. 2 to No. 10 obtained in Examples 2-10 above.

[0060] To verify the effect of the asphalt modifier provided by this invention on modified asphalt, the following comparative experiments were also conducted:

[0061] Comparative Example 1

[0062] Referring to the preparation method of Example 11, the modifier 1 added in S1 was replaced with pure PE, and the PE content was 5%, thus obtaining PE modified asphalt.

[0063] Comparative Example 2

[0064] Referring to the preparation method of Example 11, the modifier No. 1 added in S1 was replaced with 5% pure PE + 2.5% organic montmorillonite. Specifically, in the S1 process, 5% pure PE was added first, followed by 2.5% organic montmorillonite, to obtain PE + organic montmorillonite modified asphalt.

[0065] Comparative Example 3

[0066] Referring to the preparation method of Example 11, the modifier No. 1 added in S1 was replaced with 5% pure PE + 1.25% aluminum stearate. Specifically, in the preparation process, 5% pure PE + 1.25% aluminum stearate were first blended and extruded to obtain granules, and then the granules were added in the S1 process to obtain modified asphalt.

[0067] Comparative Example 4

[0068] Referring to the preparation method of Example 11, the modifier No. 1 added in S1 was replaced with 5% pure PE + 1% CaCO3. Specifically, in the preparation process, 5% pure PE + 1% CaCO3 was first blended and extruded to obtain granules, and then the granules were added in the S1 process to obtain modified asphalt.

[0069] Comparative Example 5

[0070] Referring to the preparation method of Example 11, the modifier No. 1 added in S1 was replaced with 5% pure PE + 1.25% aluminum stearate + 2.5% organomontmorillonite. Specifically, in the S1 process, 5% pure PE, 1.25% aluminum stearate and 2.5% organomontmorillonite were added sequentially, and the modified asphalt was obtained without extrusion.

[0071] Comparative Example 6

[0072] Referring to the preparation method of Example 11, the modifier No. 1 added in S1 was replaced with 5% pure PE + 1% CaCO3 + 2.5% organomontmorillonite. Specifically, in the preparation process, 5% pure PE, 1% CaCO3 and 2.5% organomontmorillonite were added sequentially in the S1 process, and the modified asphalt was obtained without extrusion.

[0073] Comparative Example 7

[0074] Unmodified 70# base asphalt was used as a blank control group, which was recorded as Comparative Example 7.

[0075] To verify the feasibility and effectiveness of the present invention, the modified asphalts prepared in Examples 11-20 and Comparative Examples 1-7 were subjected to the following performance tests:

[0076] 1. The modified asphalt or asphalt prepared in the above examples and comparative examples were subjected to penetration test, ductility test, softening point test (ring and ball method), and segregation test according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 1 and... Figure 1 As shown.

[0077] 2. The modified asphalt or asphalt prepared in Examples 11-13, 16-17 and Comparative Examples 1-4 were subjected to XRD and fluorescence microscopy tests according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are as follows: Figure 2 , Figure 3 As shown.

[0078]

[0079] The results of the above experiments are analyzed as follows:

[0080] (1) As shown in Table 1, the asphalt modifier prepared by the present invention using waste plastic PE as raw material and adding nucleating agent and organomontmorillonite to modify the base asphalt showed that, for the organic nucleating agent (Examples 11-15), changing the ratio of PE to organic nucleating agent resulted in a decrease in penetration of the modified asphalt by 11.1%, 18.5%, 24.1%, 29.6%, and 35.2% respectively compared to the unmodified asphalt; the softening point was continuously increasing. For the inorganic nucleating agent (Examples 16-20), changing the ratio of PE to inorganic nucleating agent resulted in a decrease in penetration of the modified asphalt by 9.3%, 14.8%, 18.5%, 22.2%, and 33.3% respectively compared to the unmodified asphalt; the softening point was also continuously increasing. The data indicate that the asphalt modifier provided by the present invention can improve the high-temperature performance of ordinary petroleum asphalt.

[0081] (2) Compared with Comparative Examples 1 and 2, the asphalt modified by the modifier provided by the present invention has better compatibility with the matrix asphalt than that modified by pure PE asphalt (Comparative Example 1). This is because the temperature difference caused by segregation in the modified asphalt prepared by the modifier of the present invention is smaller than that in the modified asphalt prepared by the PE asphalt modifier (the smaller the temperature difference, the better). This may be because the nucleating agent induces PE molecules to nucleate, making the molecules change from disorder to order, which significantly improves the overall crystal density of the plastic phase, thereby playing a role in balancing the density.

[0082] (3) Compared with Comparative Examples 1, 3, and 4, the embodiments of the present invention show that even without the addition of organomontmorillonite, segregation still occurred when PE and nucleating agent were extruded, although it was still better than PE-modified asphalt alone. This indicates that PE, nucleating agent, and layered silicate organomontmorillonite in the embodiments of the present invention form a synergistic modification effect. Because organomontmorillonite has a typical layered structure, especially after modification with nucleating agent and within a certain range, the number of nucleation sites increases with the increase of nucleating agent, forming a large number of small, uniformly distributed spherulites. Their small size means refined spherulites with better diffusion ability, thus making it easier to intercalate into the interlayer gaps of organomontmorillonite. This successful intercalation creates a stable composite structure between the plastic phase and organomontmorillonite. This structure can effectively limit the macroscopic migration and aggregation of the plastic phase in the asphalt matrix, thereby fundamentally and significantly suppressing the common plastic segregation phenomenon in modified asphalt systems.

[0083] (4) Compared with Comparative Examples 5 and 6, it can be seen that the PE / nucleating agent / organomontmorillonite ternary mixture prepared without extrusion melt blending process exhibits better segregation stability in modified asphalt than the single PE modified system, but still shows a significant phase separation trend. In stark contrast, the sample of the present invention after extrusion treatment basically eliminated the segregation phenomenon. This result indicates that the strong shear force provided by the extrusion process is crucial for achieving the synergistic effect of the nucleating agent and organomontmorillonite. It can significantly refine the polymer phase domains, promote the intercalation and exfoliation of organomontmorillonite sheets, thereby forming a stable structure and fundamentally inhibiting the floating and aggregation of polymers.

[0084] (5) From Figure 1 The experimental results clearly show that the PE-organo-montmorillonite (OMMT)-nucleating agent ternary composite modified asphalt prepared by the twin-screw extruder in this embodiment of the invention exhibits significantly better storage stability than the system of single PE modified asphalt and the system without added organo-montmorillonite (OMMT). Under different processes and material ratios, the softening point distribution shows significant differences: in the system with only 5% PE, a significant difference in softening points exists between the upper and lower parts, indicating a large tendency for phase separation; however, after introducing organo-montmorillonite (OMMT) into this system, the difference in softening points between the upper and lower ends significantly decreases, proving that organo-montmorillonite (OMMT) has a positive effect on improving the storage stability of the system; further, by pre-treating PE and nucleating agent through twin-screw extrusion to prepare modified asphalt, the difference in softening points further decreases, indicating that the addition of the nucleating agent helps improve the dispersion and stability of PE in asphalt; when organo-montmorillonite is introduced simultaneously with PE and the nucleating agent during extrusion, the difference in softening points between the upper and lower parts basically meets the requirements, indicating that the system forms a stable composite structure in the asphalt. Compared with Comparative Examples 3 and 4, the combination of PE, organomontmorillonite, and nucleating agent through twin-screw extrusion process produced a significant synergistic effect. It not only effectively suppressed the stratification phenomenon caused by temperature changes, but also greatly improved the dispersion uniformity and long-term storage stability of each component in asphalt.

[0085] (6) Figure 2The X-ray diffraction (XRD) patterns shown illustrate the crystal structure characteristics of the composite materials obtained under different modifier ratios, and also provide the diffraction pattern of the original organo-montmorillonite (OMMT) sample as a reference. It can be clearly observed from the figures that OMMT exhibits a distinct diffraction peak near approximately 2θ = 4.5°, corresponding to the (001) crystal plane characteristic diffraction of the montmorillonite sheets. In the system using only PE and OMMT for physical mixing, the diffraction peak position shifts slightly forward, indicating an increase in the interlayer spacing of the montmorillonite. However, due to the large size of the PE molecular chains, it is difficult for them to effectively intercalate into the interior of the montmorillonite sheets, thus limiting the degree of interlayer spacing expansion. In the composite material system of PE and OMMT after extrusion treated with a nucleating agent, the aforementioned diffraction peak shifts significantly forward, and this forward shift becomes more pronounced with increasing nucleating agent ratio. This phenomenon indicates that the introduction of a nucleating agent can significantly increase the nucleation density of PE, refine the crystal size of PE, and form a finer crystal nucleus structure. The refined crystals have better diffusion capabilities, which facilitates their more effective intercalation into the layered structure. With the increase of nucleating agent dosage, more refined PE crystal nuclei successfully embedded in the montmorillonite lamellar structure, resulting in a continuous forward shift of the montmorillonite diffraction peak. This proves that the interlayer spacing of montmorillonite in the composite system is further expanded, and the interaction among the three is significantly enhanced, forming a more stable intercalated or partially exfoliated composite structure.

[0086] (7) From Figure 3 From this, we can know that Figure 3 (a) The presence of large agglomerates in PE-modified asphalt indicates poor dispersion of PE in the asphalt matrix and significant phase separation; this also aligns with... Figure 1 The phenomenon of poor storage stability in the middle. Figure 3 (c) to 3(e) show that with the increase of the appropriate amount of nucleating agent, PE forms a more stable "core-shell" structure after nucleation with the nucleating agent, effectively refining the crystal size and improving its dispersion uniformity in asphalt. From Figure 3 (f) and 3(g), after the inorganic nucleating agent is synergistically combined with PE and organomontmorillonite, the dispersion state also becomes a more uniform system with the increase of the amount of nucleating agent. Figure 1 The storage stability in it is consistent with the phenomenon.

[0087] Based on the same inventive concept, asphalt concrete prepared by mixing modified asphalt obtained using the method of this invention with mineral aggregates has the same technical effects as the modified asphalt of this invention. Therefore, it should also be within the protection scope of this invention.

[0088] The above description is only a part of the preferred embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An asphalt modifier, characterized in that, It is produced by co-extrusion using waste plastics, nucleating agents, and organomontmorillonite as raw materials; the main component of the waste plastics is PE, and the PE content in the waste plastics is 68.9%~78.8%; The weight ratio of organomontmorillonite to PE is 1:1.5~2.5; the weight ratio of nucleating agent to PE is 1:2~6.

2. The asphalt modifier according to claim 1, characterized in that, The amount of the asphalt modifier in the base asphalt is 4wt%~7wt% based on PE.

3. The asphalt modifier according to claim 1, characterized in that, The nucleating agent is an organic nucleating agent or an inorganic nucleating agent; The organic nucleating agent is any one of aluminum stearate, calcium stearate, or organophosphate nucleating agents; The inorganic nucleating agent is any one of CaCO3, talc, or silicon dioxide.

4. The asphalt modifier according to claim 1, characterized in that the asphalt... The preparation method of the modifier is as follows: (1) The recycled waste plastic is rinsed to remove surface stains and dried, then crushed, ground and screened to obtain waste plastic granules; the particle size of the plastic granules is ≤5mm; (2) The waste plastic particles obtained in (1) are blended with nucleating agent and organic montmorillonite according to a preset ratio and extruded to obtain the asphalt modifier, and the particle size of the asphalt modifier is controlled to be ≤220 mesh.

5. The asphalt modifier according to claim 4, characterized in that, (1) The rinsing time is 2h~6h; the drying conditions are: 75℃~90℃ for 2h~4h.

6. A method for modifying asphalt using organomontmorillonite in conjunction with waste plastics and nucleating agents, characterized in that, Includes the following steps: S1. Melt the base asphalt by heating, then add the asphalt modifier as described in any one of claims 1 to 5, controlling the temperature at 160 to 170°C, stirring constantly while adding to prevent agglomeration; the amount of the asphalt modifier in the base asphalt is 4 wt% to 7 wt% based on PE. S2. Next, a disperser is used to perform preliminary dispersion and stirring at a rate of 200~300 rad / min. S3. After the initial dispersion and mixing is completed, control the shear rate to 4500~5000r / min and perform high-speed shearing on the mixture for 45~60min, while controlling the temperature at 170~180℃. S4. Disperse and stir at a high speed of 300~450 rad / min to obtain the final product.

7. The method according to claim 6, characterized in that, In S1, the base bitumen is heated at 140~150℃ for 30~35 minutes to melt it.

8. The method according to claim 6, characterized in that, The initial dispersion and stirring time of S2 should be controlled at 10~15 min.

9. The method according to claim 6, characterized in that, The high-speed dispersion stirring time of S4 is controlled at 15~20min, and the temperature is controlled at 170~185℃.

10. Modified asphalt prepared by the method of modifying asphalt with organomontmorillonite in conjunction with waste plastics and nucleating agents as described in any one of claims 6 to 9.

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