Rubber-plastic composite modified asphalt suitable for low-temperature regions and preparation method thereof

Abstract

The invention provides rubber-plastic composite modified asphalt suitable for low-temperature regions and a preparation method thereof, and belongs to the technical field of modified asphalt preparation. The modified asphalt is prepared from matrix asphalt, rubber powder, polyethylene and a compatibilizer, the content of the rubber powder is 15%-25% of the weight of the matrix asphalt, the content of the polyethylene is 4%-6% of the weight of the matrix asphalt, and the content of the compatibilizer is 5%-15% of the weight of the matrix asphalt; the preparation method comprises the following steps: heating the matrix asphalt to a flowing state, adding the rubber powder, stirring and swelling for 60 minutes, adding the polyethylene and the compatibilizer, stirring, and shearing at a high speed of 5000r / min for 45-60 minutes. Through rubber and plastic compound modification, the low-temperature crack resistance, the high-temperature stability and the water stability are excellent, the storage stability is good, the cost and pollution are reduced by utilizing waste materials, the process is simple, and the low-temperature road pavement material is suitable for road engineering in low-temperature areas.

Description

Technical Field

[0001] This invention relates to the field of modified asphalt preparation technology, and in particular to a rubber-plastic composite modified asphalt suitable for low-temperature regions and its preparation method. Background Technology

[0002] Globally, approximately 1.4 billion tires are consumed annually. These tires become waste tires at the end of their service life, and their accumulation causes severe environmental pollution. Waste tires are difficult to degrade naturally, occupying large amounts of land resources over time. Under natural conditions such as wind, sun, and rain, they may release harmful substances, polluting soil, water, and air. Furthermore, the disposal of large quantities of waste plastic products is a major problem facing humanity. The massive consumption of plastics puts enormous pressure on the ecological environment. Waste plastics are difficult to decompose in nature; currently, only a small portion is recycled, while the majority seeps into the ocean, endangering marine life and ecosystems. In the past, waste rubber has been widely used in road paving, giving asphalt higher viscosity and elasticity, and improving its low-temperature flexibility, but its high-temperature performance is poor. The addition of waste plastics can significantly improve the high-temperature performance of asphalt and minimize low-temperature cracking. Therefore, adding both waste tires and waste plastics to the base asphalt can improve the high and low-temperature performance of road surfaces and solve the problem of waste pollution, which is of great significance to global development.

[0003] Rubber, plastics, and asphalt differ significantly in chemical structure, density, and molecular weight. From a thermodynamic perspective, rubber and plastics are difficult to integrate well when used to modify asphalt. This incompatibility leads to phase separation during storage and transportation, severely impacting the performance of the modified asphalt. Furthermore, rubber-plastic composite modified asphalt exhibits poor performance at low temperatures, and current research largely suggests that this material is better suited for high-temperature applications; therefore, continued efforts are needed to improve its low-temperature performance. In addition, the storage stability of rubber-plastic composite modified asphalt also requires significant improvement.

[0004] Therefore, developing a rubber-plastic composite modified asphalt suitable for low-temperature regions that can balance high and low temperature performance, improve storage stability, and use waste rubber and plastic materials as raw materials has important practical significance and application value. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a rubber-plastic composite modified asphalt suitable for low-temperature regions and its preparation method. Through rubber-plastic composite modification, it takes into account excellent low-temperature crack resistance, high-temperature stability and water stability, good storage stability, and uses waste materials to reduce costs and pollution. The process is simple and suitable for road engineering in low-temperature regions.

[0006] To achieve the above objectives, the present invention provides the following solution: A rubber-plastic composite modified asphalt suitable for low-temperature regions is prepared from base asphalt, rubber powder, polyethylene and compatibilizer, wherein the content of rubber powder is 15% to 25% of the weight of the base asphalt, the content of polyethylene is 4% to 6% of the weight of the base asphalt, and the content of compatibilizer is 5% to 15% of the weight of the base asphalt.

[0007] Preferably, the base asphalt has a penetration of 8-10 mm and a softening point greater than 44°C.

[0008] Preferably, the rubber powder is obtained by crushing waste tires, and the mesh size of the rubber powder is 60 mesh to 80 mesh.

[0009] Preferably, the polyethylene is made from waste plastics made of low-density polyethylene or virgin low-density polyethylene.

[0010] Preferably, the compatibilizer is an aromatic oil.

[0011] The present invention also provides a method for preparing the above-mentioned rubber-modified asphalt suitable for low-temperature regions, comprising the following steps: S1. Heat the base asphalt to a fluid state and place it in a beaker. Then place the beaker containing the base asphalt in a heating jacket. S2. Add rubber powder to the treated matrix asphalt, stir until there is no obvious clumping, and then swell at the set temperature for 60 minutes to obtain the product. S3. Add polyethylene and compatibilizer to the product, stir until no modified particles are visible to the naked eye, and then perform high-speed shearing treatment to obtain rubber-plastic composite modified asphalt.

[0012] Preferably, in step S1, the base asphalt is heated to a fluid state at a temperature of 100~120℃; the temperature of the heating jacket is set to 175~185℃.

[0013] Preferably, in steps S2 and S3, the stirring is done manually with a glass rod for 5 minutes; the set temperature is 175~185℃.

[0014] Preferably, the high-speed shearing process involves a rotation speed of 5000 r / min, a shearing time of 45-60 min, and a temperature of 175-185℃ during the shearing process.

[0015] In addition, the present invention also provides an application of the rubber-plastic composite modified asphalt suitable for low-temperature regions in road engineering in low-temperature regions.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) This invention incorporates rubber powder obtained from waste tires and polyethylene into the base asphalt. The flexibility of the rubber powder can improve the low-temperature crack resistance of the modified asphalt, while polyethylene can enhance its high-temperature stability. The synergistic effect of the two makes the modified asphalt have excellent high and low temperature performance, solving the problem of the limited performance of a single modifier.

[0017] (2) In the technical solution of the present invention, the addition of compatibilizer can promote the swelling of rubber powder and polyethylene in the matrix asphalt, improve the compatibility between the three, reduce the phase separation phenomenon of modified asphalt during storage and transportation, and effectively improve its storage stability.

[0018] (3) The present invention uses rubber powder made from waste tires and polyethylene made from waste plastics as raw materials, which not only reduces the preparation cost of modified asphalt, but also provides a way to recycle waste rubber and plastic materials, reducing their pollution to the environment and meeting the development needs of environmentally friendly materials.

[0019] (4) The preparation method provided by the present invention adopts a two-step stirring and high-speed shearing method, which is simple to operate and does not require complicated equipment and processes. It is conducive to improving production efficiency and facilitating large-scale factory production. The prepared rubber-plastic composite modified asphalt has good low-temperature crack resistance, high-temperature stability and storage stability, and is easy to construct and pave. It is suitable for road engineering in low-temperature areas and has broad application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for preparing rubber-plastic composite modified asphalt suitable for low-temperature regions according to the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, this invention provides a method for preparing rubber-modified composite asphalt suitable for low-temperature regions, comprising the following steps: S1. Heat the base asphalt to a fluid state and place it in a beaker. Then place the beaker containing the base asphalt in a heating jacket. Specifically, the temperature at which the base asphalt is heated to a fluid state is 100~120℃; the temperature of the heating jacket is set to 175~185℃.

[0025] S2. Add rubber powder to the treated matrix asphalt, stir until there is no obvious clumping, and then swell at the set temperature for 60 minutes to obtain the product. S3. Add polyethylene and compatibilizer to the product, stir until no modified particles are visible to the naked eye, and then perform high-speed shearing treatment to obtain rubber-plastic composite modified asphalt.

[0026] Specifically, in steps S2 and S3, the stirring is performed manually with a glass rod for 5 minutes; the set temperature is 175~185℃; the high-speed shearing speed is 5000 r / min; the shearing time is 45~60 minutes; and the temperature is maintained at 175~185℃ during the shearing process.

[0027] Based on the above, the present invention also provides a rubber-modified composite asphalt suitable for low-temperature regions, which is prepared from base asphalt, rubber powder, polyethylene and compatibilizer, wherein the content of rubber powder is 15% to 25% of the weight of base asphalt, the content of polyethylene is 4% to 6% of the weight of base asphalt, and the content of compatibilizer is 5% to 15% of the weight of base asphalt.

[0028] The matrix asphalt has a penetration of 8-10 mm and a softening point greater than 44℃; the rubber powder is obtained by crushing waste tires and has a mesh size of 60-80 mesh; the polyethylene is made from waste plastics or virgin low-density polyethylene; and the compatibilizer is aromatic oil.

[0029] The above content will be further verified through specific implementation methods below. The described embodiments are only the optimal embodiments of the present invention, including but not limited to all implementation methods.

[0030] Example 1 This embodiment provides a method for preparing rubber-plastic composite modified asphalt suitable for low-temperature regions, including the following steps: Step 1: Heat the base asphalt in a 130℃ oven until it reaches a fluid state. Then weigh a certain mass of base asphalt and place it in a heating jacket to heat to 180℃. After the temperature stabilizes, add different amounts of rubber powder and stir manually with a glass rod until evenly mixed. Then maintain the temperature at 180℃ to allow the rubber powder to fully swell for 1 hour.

[0031] Step 2: After the rubber powder has fully swelled, add different amounts of polyethylene and aromatic oil to the mixture in step 1, and stir the mixture with a glass rod until there are no visible particles. Then, shear the mixture continuously for 30 minutes at a speed of 5000 r / min.

[0032] Step 3: After shearing, place the modified asphalt obtained in Step 2 in an oven at 180℃ and let it mature for 1 hour to prepare rubber-plastic composite modified asphalt.

[0033] This embodiment uses orthogonal experimental design to investigate the effects of different dosages of rubber powder, polyethylene, and aromatic oil on the performance of rubber-plastic composite modified asphalt, in order to determine the optimal mix ratio. The experiment employs a three-factor, three-level design, with the specific factors and levels shown in Table 1 below: Table 1. Factors and Levels of Orthogonal Experiment

[0034] By analyzing the R-values ​​(extreme values) under different indicators, the influence of factors A, B, and C on the indicator can be determined in turn. The larger the R-value, the greater the influence of that factor. k1, k2, and k3 represent the degree of influence of each different level value, and the larger the value, the greater the degree of influence. According to the above factors and levels, rubber-plastic composite modified asphalt was prepared, and its penetration, softening point, ductility, viscosity at 180℃, storage stability (48h softening point difference), creep rate at -18℃, and aging index were tested. The test results are shown in Table 2 below: Table 2 Analysis of Orthogonal Experiment Results

[0035] Analysis of the orthogonal test results under various indicators, as shown in Table 2, reveals that polyethylene can improve high-temperature performance by absorbing lightweight components in asphalt to form an elastic network. However, increasing the content of polyethylene and rubber powder significantly increases asphalt viscosity and leads to poorer storage stability. The incorporation of aromatic oil dilutes the network structure in the modified asphalt system, thereby reducing high-temperature performance, but it can promote the swelling of the modifier and improve storage stability. Considering the results of all performance tests, the optimal combination of the three modifiers was finally selected as 25% rubber powder, 4% polyethylene, and 15% aromatic oil.

[0036] Example 2 To verify the road performance of the rubber-plastic composite modified asphalt prepared in Example 1, this example determined its optimal asphalt-aggregate ratio through a Marshall test and compared it with the performance of conventional rubber asphalt mixtures.

[0037] The rubber-plastic composite modified asphalt prepared using the optimal proportions in Example 1 (25% rubber powder, 4% polyethylene, and 15% aromatic oil) was determined to have an optimal asphalt-aggregate ratio of 4.3% by Marshall test according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The modified asphalt and aggregate were mixed according to this asphalt-aggregate ratio and stirred evenly at 165℃~175℃ to produce a rubber-plastic composite modified asphalt mixture.

[0038] A conventional rubber asphalt mixture containing only 25% rubber powder (with the same base asphalt and aggregate gradation) was selected as a control group. The high-temperature stability, low-temperature crack resistance, and water stability of the two mixtures were tested, and the results are shown in Table 3. Table 3. Performance test results of the mixture for road use (average value)

[0039] As shown in Table 3, the dynamic stability of the rubber-plastic composite modified asphalt mixture was 37.5% higher than that of the rubber asphalt mixture, indicating that the rubber-plastic composite modifier has a good effect on improving the high-temperature performance of the base asphalt. For the rubber-plastic composite modified asphalt, the presence of polyethylene increases the stiffness of the asphalt mixture, but the presence of aromatic oil can replenish the lightweight components absorbed by the rubber and polyethylene in the asphalt, thereby reducing the formation of cracks at low temperatures and improving the low-temperature crack resistance of the asphalt mixture. The residual stability after water immersion of the rubber asphalt mixture and the rubber-plastic composite modified asphalt mixture is roughly the same, but the freeze-thaw splitting tensile strength ratio of the rubber-plastic composite modified asphalt mixture is higher than that of the rubber asphalt mixture, indicating that the rubber-plastic composite modified asphalt enhances the adhesion between the asphalt and aggregates, maintaining a high bond strength even after water damage, thus improving the water stability of the mixture.

[0040] Therefore, the above-mentioned rubber-plastic composite modified asphalt suitable for low-temperature regions and its preparation method, through rubber-plastic composite modification, takes into account excellent low-temperature crack resistance, high-temperature stability and water stability, good storage stability, and utilizes waste materials to reduce costs and pollution. The process is simple and suitable for road engineering in low-temperature regions.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0042] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A rubber-plastic composite modified asphalt suitable for low-temperature regions, characterized in that, It is prepared from base asphalt, rubber powder, polyethylene and compatibilizer, wherein the content of rubber powder is 15% to 25% of the weight of base asphalt, the content of polyethylene is 4% to 6% of the weight of base asphalt, and the content of compatibilizer is 5% to 15% of the weight of base asphalt.

2. The rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 1, characterized in that, The base asphalt has a penetration of 8-10 mm and a softening point greater than 44℃.

3. The rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 1, characterized in that, The rubber powder is obtained by crushing waste tires, and the mesh size of the rubber powder is 60-80 mesh.

4. The rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 1, characterized in that, The polyethylene is made from waste plastics made of low-density polyethylene or from virgin low-density polyethylene.

5. The rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 1, characterized in that, The compatibilizer is an aromatic oil.

6. A method for preparing rubber-modified composite asphalt suitable for low-temperature regions according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Heat the base asphalt to a fluid state and place it in a beaker. Then place the beaker containing the base asphalt in a heating jacket. S2. Add rubber powder to the treated matrix asphalt, stir until there is no obvious clumping, and then swell at the set temperature for 60 minutes to obtain the product. S3. Add polyethylene and compatibilizer to the product, stir until no modified particles are visible to the naked eye, and then perform high-speed shearing treatment to obtain rubber-plastic composite modified asphalt.

7. The method for preparing rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 6, characterized in that, In step S1, the base asphalt is heated to a fluid state at a temperature of 100~120℃; the temperature of the heating jacket is set to 175~185℃.

8. The method for preparing rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 6, characterized in that, In steps S2 and S3, the stirring is performed manually with a glass rod for 5 minutes; the set temperature is 175~185℃.

9. The method for preparing rubber-plastic composite modified asphalt suitable for low-temperature regions according to claim 6, characterized in that, The high-speed shearing process involves a rotation speed of 5000 r / min, a shearing time of 45-60 min, and a temperature of 175-185℃ during the shearing process.

10. The application of the rubber-plastic composite modified asphalt according to any one of claims 1 to 5 in road engineering in low-temperature regions.

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