Pavement milling material recycled asphalt mixture based on epoxy system and preparation method of pavement milling material recycled asphalt mixture

Abstract

The invention discloses a pavement milling material recycled asphalt mixture based on an epoxy system and a preparation method of the pavement milling material recycled asphalt mixture. The preparation method comprises the following steps: step 1, RAP pretreatment; step 2, premixing an epoxy system; step 3, fusion of the aggregate and asphalt: adding the RAP and the aggregate, heating to 140-150 DEG C, and adding new asphalt under high-speed hot stirring to form a mixture; step 4, doping into an epoxy system: adding epoxy premixed liquid drops into the mixture at 140-150 DEG C, and continuously carrying out high-speed thermal stirring; in the stirring process, the curing agent and the epoxy resin are subjected to a cross-linking reaction to form a three-dimensional epoxy net structure; an epoxy group of the epoxy resin and an active group in the asphalt are subjected to chemical reaction to form a chemical bond, so that the molecular structure of the asphalt is reconstructed; then, the reconstructed asphalt molecules are embedded into the epoxy network structure to form the regenerated asphalt mixture with the epoxy-asphalt interpenetrating network structure, so that the problems of insufficient performance recovery, low road index, poor construction adaptability and high cost in the existing RAP regeneration technology are solved.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials technology, and in particular to a road milling material recycled asphalt mixture based on an epoxy system and its preparation method. Background Technology

[0002] Driven by the global demand for sustainable development in road engineering, the recycling of rough asphalt pavement (RAP) has become a core issue of concern in the industry and a key path to achieving low-carbon development in road engineering. RAP contains a large amount of aged asphalt and aggregate, with aggregate accounting for approximately 80%-90% and aged asphalt accounting for approximately 3%-6%. Due to long-term exposure to natural environments (sunlight, temperature changes, rainwater erosion) and traffic loads, this aged asphalt has undergone severe oxidative aging and component migration, resulting in molecular chain breakage, reduced aromatic and saturated component content, and increased asphaltene content. Ultimately, this manifests as a significant decrease in adhesion, a substantial decline in low-temperature crack resistance, and a significant reduction in high-temperature stability. Directly reusing RAP in road construction cannot meet the requirements for load-bearing capacity and durability. Therefore, it is necessary to repair the performance of aged asphalt through effective technical means. Currently, existing RAP recycling technologies in the industry can be mainly divided into the following categories: Traditional Recycling Agent Regeneration Technology: This technology adds petroleum-based recycling agents to RAP (Rich Asphalt Powder), utilizing the lightweight components (aromatic and saturated components) in the recycling agent to replenish the lightweight components lost in aged asphalt, thereby temporarily softening the aged asphalt. However, this repair method only reaches the level of physical softening and cannot reconstruct the molecular structure of aged asphalt, leading to a rapid long-term performance degradation of the recycled mixture. Engineering practice shows that recycled asphalt mixtures prepared using traditional recycling agents have a service life 30%-50% shorter than newly constructed asphalt pavements, and are typically only suitable for base or subbase courses of low-grade roads, making them difficult to apply to pavement surface courses with higher performance requirements. Epoxy Asphalt Regeneration Technology: To improve the performance of recycled mixtures, some research institutions and companies have attempted to introduce epoxy systems into the RAP recycling process. Epoxy asphalt has advantages such as high strength, high stability, and high durability, and theoretically can effectively improve the performance of aged asphalt. However, existing epoxy asphalt recycling technologies have several drawbacks: Firstly, the compatibility issue between the epoxy system and aged asphalt has not been fully resolved. If the epoxy crosslinking density is too high, it can increase the brittleness of the mixture, making it prone to cracking at low temperatures. Secondly, insufficient curing can lead to inadequate bond strength, resulting in damage such as shoving and rutting under traffic loads. Thirdly, existing technologies often rely on specific types of epoxy resins and curing agents, which not only have poor compatibility but also result in high raw material prices, significantly increasing engineering costs and hindering large-scale application. Conventional hot recycling technology involves heating, crushing, and screening RAP (reclaimed asphalt), then mixing it with new aggregates and asphalt to prepare recycled asphalt mixtures. However, this technology typically requires heating temperatures above 180°C to promote asphalt fusion and reaction. This not only increases energy consumption and carbon emissions but also causes secondary aging of the aged asphalt in the RAP, further accelerating the degradation of asphalt performance, which contradicts the current demand for low-carbon and environmentally friendly development. Furthermore, conventional hot recycling processes require sophisticated equipment, including specialized heating and mixing equipment, resulting in high construction costs. In summary, current RAP recycling technologies still suffer from limited performance restoration, insufficient road performance, poor construction adaptability, and high costs. Developing a recycling technology that can efficiently restore the performance of aged RAP asphalt, balance road performance and construction convenience, and not rely on specific types of epoxy raw materials, has become a critical issue urgently needing to be addressed in the road engineering field, and is also an inevitable requirement for promoting the sustainable development of the road engineering industry. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing an epoxy-based recycled asphalt mixture from road milling and its preparation method. This epoxy-based recycled asphalt mixture from road milling and its preparation method can overcome the defects of existing RAP recycling technology. Through the synergistic design of "epoxy system (epoxy resin + curing agent) + new asphalt", the molecular reconstruction and performance repair of aged asphalt in RAP are achieved. At the same time, the preparation process is optimized to reduce energy consumption, and finally a recycled asphalt mixture with excellent high-temperature stability, strong low-temperature crack resistance, good adhesion, and low carbon and environmental protection is obtained, which meets the requirements of high-grade pavement.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing recycled asphalt mixture based on epoxy system road milling material includes the following steps.

[0005] Step 1, RAP pretreatment: The recycled road milling material RAP is screened to remove impurities and dried for later use.

[0006] Step 2, Premixing the epoxy system: At room temperature, stir the epoxy resin and curing agent at a low speed of no more than 100 r / min to form an epoxy premixed liquid.

[0007] Step 3: Blending aggregate and asphalt: Add the pretreated road milling material RAP and aggregate to a heated mixing pot and heat to 140-150℃. Then, add new asphalt to the heated mixing pot under high-speed hot mixing at 100-150r / min and maintain high-speed hot mixing to blend the new asphalt with the aged asphalt in the road milling material RAP to form a mixture.

[0008] Step 4: Incorporating the epoxy system: Maintain the stirring temperature at 140-150℃, drop the epoxy premix from Step 2 into the mixture from Step 3, and continue stirring for at least 10 minutes. During stirring, the curing agent in the epoxy premix undergoes a cross-linking reaction with the epoxy resin, forming a three-dimensional epoxy network structure. Simultaneously, the epoxy groups of the epoxy resin in the epoxy premix react chemically with the active groups in the new and aged asphalt to form chemical bonds, reconstructing the molecular structure of the asphalt. Then, the reconstructed asphalt molecules are embedded in the epoxy network structure, forming a recycled asphalt mixture with an "epoxy-asphalt interpenetrating network structure".

[0009] It also includes step 5, finished product testing: Marshall stability, flow value and void ratio are tested on the recycled asphalt mixture formed in step 4. The recycled asphalt mixture that passes the test can be discharged for road paving.

[0010] In step 5, the recycled asphalt mixture formed in step 4 is tested for Marshall stability, flow value, void ratio, high-temperature rutting test, and low-temperature bending test. The qualified test indicators are: Marshall stability ≥12kN, flow value 2.0-4.0mm, void ratio 3.0%-5.0%, high-temperature rutting dynamic stability ≥3000 cycles / mm, and low-temperature bending strain ≥2500με.

[0011] In step 1, during the screening of the road milling material RAP, impurities with a particle size >26.5mm are removed, and then the material is dried at 105-115℃ until the moisture content is ≤1.0%.

[0012] In step 2, the epoxy resin to curing agent mass ratio is 2:1. Stir at low speed of 50-80 r / min for 3-5 min until homogeneous to form an epoxy premix, avoiding premature and violent reaction.

[0013] In step 3, the high-speed hot stirring speed is 120-150 r / min.

[0014] In step 3, the new asphalt is added in two stages, specifically as follows: Add 60% of the total volume for the first time and stir for 5 minutes.

[0015] Add the remaining 40% for the second time and continue stirring for 3-7 minutes, with a total stirring time of 8-12 minutes.

[0016] By adding the new asphalt in two stages and using high-speed hot mixing, the new asphalt can fully coat the aggregate surface in the road milling material (RAP) and initially fuse with the aged asphalt, softening the structure of the aged asphalt.

[0017] In step 4, the epoxy premix is ​​added to the mixture at a rate of 5-10 mL / min, and stirring is continued for 15-20 min.

[0018] In step 4, the stirring window for the epoxy premix is ​​30-40 minutes.

[0019] The epoxy-based road milling material recycled asphalt mixture was prepared using the above-mentioned preparation method.

[0020] The present invention has the following beneficial effects: 1. Leap in core mechanical properties: The Marshall stability has increased from 9.8kN without epoxy system to 15.5kN, breaking through the specification requirement of ≥12kN for high-grade pavement, indicating that the epoxy system significantly enhances the overall strength of the mixture through chemical reaction; at the same time, the flow value is controlled at 2.8mm, which is within the optimal range of the specification, avoiding brittleness problems caused by excessive strength.

[0021] 2. Enhanced adaptability to extreme environments: Its performance advantages are particularly prominent under extreme conditions of high and low temperatures—the dynamic stability of rutting is improved by nearly 100%, solving the problem of rutting in summer; the low-temperature bending strain exceeds 2950με, meeting the crack resistance requirements of cold northern regions, which is something that traditional recycled mixtures without epoxy systems cannot achieve at the same time.

[0022] 3. Durability and reliability assurance: Improved water immersion residual stability and freeze-thaw splitting strength ratio mean that the road surface is more resistant to water damage in rainy and humid environments, which can reduce potholes, loosening and other defects; while the long-term aging stability decay rate is reduced from 37% to 13%, which directly extends the service life of the road surface and reduces the later maintenance cost.

[0023] 4. Construction compatibility: The porosity of the mixture of this invention is controlled at 3.8%, which is similar to that of the mixture without epoxy system (4.2%). This indicates that the addition of epoxy system does not change the compaction characteristics of the mixture. There is no need to replace the existing paving and compaction equipment. The construction convenience is on par with the traditional process, which is convenient for engineering promotion. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing recycled asphalt mixture based on epoxy system road milling material according to the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0026] like Figure 1 As shown, the preparation method of recycled asphalt mixture based on epoxy system road milling material includes the following steps.

[0027] Step 1, RAP pretreatment: The recovered road milling material RAP is preferably classified by a vibrating screen to remove impurities with a particle size >26.5mm, and then sent to a drying drum to dry at 105-115℃ until the moisture content is ≤1.0% for later use.

[0028] In a further embodiment, the preferred operation of the above screening is as follows: the recovered road milling material (RAP) is fed into a vibrating screen and graded using a three-layer screen (screen aperture sizes of 26.5mm, 19mm, and 9.5mm, respectively) to remove impurities with a particle size >26.5mm (such as gravel, soil lumps, etc.), and simultaneously separates the RAP into aggregates of different particle sizes (26.5-19mm, 19-9.5mm, and below 9.5mm) for subsequent gradation adjustment. During the screening process, the amplitude of the vibrating screen needs to be controlled at 3-5mm, and the vibration frequency at 25-30Hz to ensure screening efficiency and accuracy.

[0029] In a further embodiment, the preferred drying operation is as follows: the sieved RAP is fed into a continuous drying drum for drying. The heating temperature of the drying drum is controlled at 105-115℃, the rotation speed inside the drum is 3-5 r / min, and the drying time is determined according to the initial moisture content of the RAP, usually 15-25 min, so that the final moisture content of the RAP is ≤1.0%. Excessive moisture content will affect the bonding performance between asphalt and aggregate, leading to problems such as increased porosity and reduced strength in the mixture. If the heating temperature is too high, it will cause secondary aging of the aged asphalt in the RAP. Therefore, the drying temperature and time must be strictly controlled. During the drying process, the moisture content of the RAP needs to be monitored in real time using online moisture monitoring equipment to ensure the drying effect.

[0030] Step 2: Premixing the epoxy system A. Raw material preparation: Weigh the epoxy resin and curing agent according to the formula ratio, ensuring that the weighing accuracy error is ≤0.1%. Pour the epoxy resin and curing agent into clean containers separately. If the epoxy resin has a high viscosity at room temperature (such as in low-temperature environments in winter), it can be heated in a water bath at 50-60℃ for 5-10 minutes to appropriately reduce the viscosity and facilitate stirring and mixing. However, the heating temperature should not exceed 60℃ to prevent the epoxy resin from undergoing a partial curing reaction prematurely.

[0031] B. Stirring and mixing: At room temperature (25-35℃), epoxy resin and curing agent are preferably added to a low-speed stirring device (such as a planetary stirrer) at a mass ratio of 2:1. Stir at a low speed of no more than 100r / min (preferably 50-80r / min) for 3-5 minutes until uniform to form an epoxy premixed liquid, avoiding premature and violent reaction.

[0032] During the above mixing process, it is essential to ensure that the mixing blades are fully immersed in the material and that the mixture is thoroughly stirred without any obvious lumps. After mixing, a homogeneous epoxy premix will be formed. It should be used immediately or sealed and stored at room temperature for no more than 2 hours to prevent premature curing of the epoxy premix, which would affect its subsequent performance. Step 3: Blend aggregate and asphalt A. Heating: The pretreated RAP (a mixture of aggregates of different particle sizes according to the designed gradation ratio) and aggregates (preferably mineral powder) are simultaneously added to a forced-heating mixing pot. The pot lid is closed, and the heating device is turned on to raise the temperature of the mixing pot to 140-150℃. This temperature is maintained for 10-15 minutes. During the heating process, the mixture needs to be stirred every 5 minutes at a speed of 50-80 rpm to ensure uniform heating of the RAP and mineral powder and to avoid localized overheating that could lead to secondary aging of the aged asphalt.

[0033] B. Add new asphalt and mix at high speed: After the RAP and mineral powder are heated to 140-150℃, turn on the mixing device of the mixing pot and increase the mixing speed to 100-150r / min (preferably 120-150r / min), and then slowly add the weighed new asphalt.

[0034] In step 3, the new asphalt is added in two stages, specifically as follows: Add 60% of the total volume for the first time and stir for 5 minutes.

[0035] Add the remaining 40% for the second time and continue stirring for 3-7 minutes, with a total stirring time of 8-12 minutes.

[0036] By adding new asphalt in two stages and using high-speed hot mixing, the new asphalt can fully coat the aggregate surface in the road milling material (RAP) and initially fuse with the aged asphalt, softening the structure of the aged asphalt and forming a mixture.

[0037] C. Temperature Control: In this step, the heating temperature must be strictly controlled between 140-150℃, and must not exceed 150℃. If the temperature is too high, it will cause secondary aging of the aged asphalt in the RAP, and at the same time, the curing reaction speed of the epoxy system will be accelerated, which may shorten the mixing window and affect construction. If the temperature is too low, it will cause the fluidity of the asphalt to deteriorate, the epoxy premix to mix unevenly with the asphalt, and the curing reaction to be insufficient, affecting the strength and stability of the mixture. D. Mixing speed control: In this step, the mixing speed after adding new asphalt must be controlled between 120-150 r / min, and must not exceed 150 r / min. Excessive mixing speed will cause aggregate breakage in the mixture, affecting gradation; excessively low mixing speed will result in uneven mixing and segregation. Step 4: Incorporate into the epoxy system: Keep the stirring temperature at 140-150℃, drop the epoxy premix from Step 2 into the mixture from Step 3, and continue stirring for at least 10 minutes (preferably 15-20 minutes).

[0038] The following four key aspects need to be controlled during the incorporation process of the above-mentioned epoxy system.

[0039] A. Temperature control: Maintain the temperature of the heating mixing pot at 140-150℃. This temperature range has been verified by a large number of tests. It can ensure that the epoxy premix has good fluidity, which is convenient for uniform mixing with the mixture. It can also promote the chemical reaction between the epoxy system and the asphalt, while avoiding excessive temperature that may cause asphalt aging or the epoxy system to cure too quickly.

[0040] B. Adding the epoxy premix: Using a peristaltic pump, the prepared epoxy premix is ​​slowly added dropwise to the mixture in the mixing vessel at a rate of 5-10 mL / min. The purpose of slow addition is to ensure the epoxy premix is ​​evenly dispersed in the mixture, preventing localized high concentrations that could lead to excessive cross-linking density and brittleness in the mixture. Too slow a dropping rate will prolong preparation time, reduce production efficiency, and may also cause the initially added epoxy premix to solidify prematurely, affecting the overall mixing effect.

[0041] C. Stirring Speed ​​Control: While adding the epoxy premix dropwise, maintain the stirring speed of the mixing pot at 120-150 r / min and continue stirring for 15-20 min. During the stirring process, the epoxy premix undergoes a series of physicochemical reactions with the new and aged asphalt: On the one hand, the epoxy groups of the epoxy resin in the epoxy premix react chemically with the active groups (such as hydroxyl and carboxyl groups) in the new and aged asphalt to form chemical bonds, reconstructing the molecular structure of the asphalt; on the other hand, the curing agent undergoes a cross-linking reaction with the epoxy resin to form a three-dimensional epoxy network structure; simultaneously, the reconstructed asphalt molecules are embedded in the epoxy network structure, forming a recycled asphalt mixture with an "epoxy-asphalt interpenetrating network structure". This structure not only possesses the high strength and high stability of epoxy resin but also the flexibility of asphalt, significantly improving the road performance of the mixture. D. Mixing Window Control: By controlling the mixing temperature (140-150℃), mixing time, and mixing steps, the mixing window (the time from the completion of epoxy premix preparation to the loss of workability of the mixture) can be extended to 30-40 minutes. This window can meet the needs of on-site paving operations. In actual construction, the time from the completion of mixture preparation to the completion of on-site paving is usually 20-30 minutes. Therefore, a mixing window of 30-40 minutes can ensure that the mixture has good workability during paving and avoid premature curing that would prevent paving or compaction. Step 5: Finished Product Inspection A. Sampling: After the mixture is stirred, immediately take 3-5 samples randomly from the mixing pot. Each sample should weigh no less than 1.5 kg for performance testing.

[0042] B. Performance Testing: In accordance with the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), Marshall stability, flow value, and void ratio are tested on the samples. Additionally, high-temperature rutting tests, low-temperature bending tests, and immersion Marshall tests can be performed according to engineering requirements. Among these, Marshall stability ≥12kN, flow value 2.0-4.0mm, and void ratio 3.0%-5.0% are the basic indicators for a qualified mixture; high-temperature rutting dynamic stability ≥3000 cycles / mm and low-temperature bending strain ≥2500με are key indicators for meeting the requirements of high-grade pavement surface layers.

[0043] C. Discharge: If the test results meet the design requirements, open the discharge port of the mixing pot, unload the mixture into transport vehicles, and transport it to the construction site for paving. If the test results do not meet the design requirements, analyze the reasons, adjust the formula ratio or preparation process parameters, re-prepare and test until qualified. The temperature of the entire preparation process does not exceed 150℃, reducing energy consumption by more than 20% compared to traditional hot-mix asphalt mixtures (heating temperature 160-180℃), significantly reducing carbon emissions.

[0044] Existing technology uses 160-180℃ to separate aged asphalt and aggregates on the surface of RAP (Rich Asphalt and Aggregate) mix, allowing new asphalt or recycling agents to fully mix with the aged asphalt. However, the drawback of this approach is that excessively high temperatures can cause further thermal aging of the aged asphalt, leading to a decrease in asphalt viscosity and properties, thus affecting the performance of the mixture.

[0045] In this invention, due to the use of an epoxy system, which has good adhesion and solubility, it can form a cross-linked network with aged asphalt. Even when the stirring temperature is reduced to 140-150℃, it does not affect the full miscibility of the aged asphalt and the epoxy system. Not only is there no loss of function, but the performance of the epoxy recycled mixture is significantly better than that of traditional recycled mixtures without an epoxy system.

[0046] To further verify the technical advantages of this invention, RAP (aged asphalt content 4.2%, aggregate crushing value 24%) generated from a highway resurfacing project was selected. "Epoxy Recycled Mixture of this Invention" and "Traditional Recycled Mixture without Epoxy System" were prepared separately. Comparative tests were conducted using the same gradation (AC-13C) and preparation process (the only difference being whether or not an epoxy system was added). The test data are shown in Table 1. Table 1 Comparison of Road Performance Test Results

[0047] The comparative data above clearly demonstrates that the addition of the epoxy system has a "comprehensive and significant" effect on improving the performance of recycled mixtures. 1. Leap in core mechanical properties: The Marshall stability has increased from 9.8kN without epoxy system to 15.5kN, breaking through the specification requirement of ≥12kN for high-grade pavement, indicating that the epoxy system significantly enhances the overall strength of the mixture through chemical reaction; at the same time, the flow value is controlled at 2.8mm, which is within the optimal range of the specification, avoiding brittleness problems caused by excessive strength.

[0048] 2. Enhanced adaptability to extreme environments: Its performance advantages are particularly prominent under extreme conditions of high and low temperatures—the dynamic stability of rutting is improved by nearly 100%, solving the problem of rutting in summer; the low-temperature bending strain exceeds 2950με, meeting the crack resistance requirements of cold northern regions, which is something that traditional recycled mixtures without epoxy systems cannot achieve at the same time.

[0049] 3. Durability and reliability assurance: Improved water immersion residual stability and freeze-thaw splitting strength ratio mean that the road surface is more resistant to water damage in rainy and humid environments, which can reduce potholes, loosening and other defects; while the long-term aging stability decay rate is reduced from 37% to 13%, which directly extends the service life of the road surface and reduces the later maintenance cost.

[0050] 4. Construction compatibility: The porosity of the mixture of this invention is controlled at 3.8%, which is similar to that of the mixture without epoxy system (4.2%). This indicates that the addition of epoxy system does not change the compaction characteristics of the mixture. There is no need to replace the existing paving and compaction equipment. The construction convenience is on par with the traditional process, which is convenient for engineering promotion.

[0051] This invention provides a road milling aggregate (RAP) recycled asphalt mixture based on an epoxy system, prepared using the above-described method. This provides a basis for the efficient recycling and utilization of RAP in my country's road construction and contributes to my country's early achievement of its dual-carbon goals. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing recycled asphalt mixture from road milling material based on an epoxy system, characterized in that: Includes the following steps: Step 1, RAP pretreatment: The recycled road milling material RAP is screened to remove impurities and dried for later use; Step 2, Premixing the epoxy system: At room temperature, stir the epoxy resin and curing agent at a low speed of no more than 100 r / min to form an epoxy premixed liquid. Step 3: Integrating aggregates and asphalt: Add the pretreated road milling material RAP and aggregates to a heated mixing pot and heat to 140-150℃. Then, add new asphalt to the heated mixing pot under high-speed hot mixing at 100-150r / min and maintain high-speed hot mixing to integrate the new asphalt with the aged asphalt in the road milling material RAP to form a mixture. Step 4: Incorporating the epoxy system: Maintain the stirring temperature at 140-150℃, drop the epoxy premix from Step 2 into the mixture from Step 3, and continue stirring for at least 10 minutes. During stirring, the curing agent in the epoxy premix undergoes a cross-linking reaction with the epoxy resin, forming a three-dimensional epoxy network structure. Simultaneously, the epoxy groups of the epoxy resin in the epoxy premix react chemically with the active groups in the new and aged asphalt to form chemical bonds, reconstructing the molecular structure of the asphalt. Then, the reconstructed asphalt molecules are embedded in the epoxy network structure, forming a recycled asphalt mixture with an "epoxy-asphalt interpenetrating network structure".

2. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: It also includes step 5, finished product testing: Marshall stability, flow value and void ratio are tested on the recycled asphalt mixture formed in step 4. The recycled asphalt mixture that passes the test can be discharged for road paving.

3. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 2, characterized in that: In step 5, the recycled asphalt mixture formed in step 4 is tested for Marshall stability, flow value, void ratio, high-temperature rutting test, and low-temperature bending test. The qualified test indicators are: Marshall stability ≥12kN, flow value 2.0-4.0mm, void ratio 3.0%-5.0%, high-temperature rutting dynamic stability ≥3000 cycles / mm, and low-temperature bending strain ≥2500με.

4. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 1, during the screening of the road milling material RAP, impurities with a particle size >26.5mm are removed, and then the material is dried at 105-115℃ until the moisture content is ≤1.0%.

5. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 2, the epoxy resin to curing agent mass ratio is 2:

1. Stir at low speed of 50-80 r / min for 3-5 min until homogeneous to form an epoxy premix, avoiding premature and violent reaction.

6. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 3, the high-speed hot stirring speed is 120-150 r / min.

7. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 3, the new asphalt is added in two stages, specifically as follows: Add 60% of the total volume for the first time and stir for 5 minutes; Add the remaining 40% for the second time, and continue stirring for 3-7 minutes, with the total stirring time controlled at 8-12 minutes; By adding the new asphalt in two stages and using high-speed hot mixing, the new asphalt can fully coat the aggregate surface in the road milling material (RAP) and initially fuse with the aged asphalt, softening the structure of the aged asphalt.

8. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 4, the epoxy premix is ​​added to the mixture at a rate of 5-10 mL / min, and stirring is continued for 15-20 min.

9. The method for preparing recycled asphalt mixture based on epoxy system road milling material according to claim 1, characterized in that: In step 4, the stirring window for the epoxy premix is ​​30-40 minutes.

10. A road milling material recycled asphalt mixture based on an epoxy system, characterized in that: It is prepared according to any one of claims 1 to 9.

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