Environment-friendly long-acting slow-release low-freezing-point asphalt pavement material and preparation method thereof

Abstract

The invention relates to the field of road engineering materials, in particular to an environment-friendly long-acting slow-release low-freezing-point asphalt pavement material which comprises the following raw materials in parts by mass: 60-70 parts of coarse aggregate, 20-30 parts of fine aggregate, 3.5-5.8 parts of mineral powder, 0.2-0.5 part of core-shell microcapsules, 4-6 parts of asphalt, 3-5 parts of a nano montmorillonite stabilizer, 0.5-1 part of carbon nanotubes and 1-2 parts of a tea polyphenol derivative corrosion inhibitor. 0.01 to 0.06 part of a low-temperature mixing auxiliary agent; compared with the prior art, the tea polyphenol derivative has better environmental protection property, long-acting slow-release anti-freezing capability, high-temperature stability, anti-scattering performance and process compatibility, meanwhile, unification of low pollution, long service life and high and low temperature adaptability is achieved through the synergistic effect of the core-shell microcapsules and the nano-montmorillonite, the core-shell microcapsules, the tea polyphenol derivative and the nano-montmorillonite can directly replace mineral powder, and the preparation method is simple and convenient. And the core-shell slow-release structure forms a gradient porous structure through citric acid steam cross-linking, the staged release of an anti-freezing factor is controlled, and the preparation method has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of road engineering materials, and in particular to an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material and its preparation method. Background Technology

[0002] Currently, chloride-based low-freezing-point asphalt pavement materials (such as sodium chloride and calcium chloride) are commonly used as an active snow and ice melting technology for roads in cold regions. However, these materials have the following significant drawbacks: Chloride ions can easily seep into the soil and groundwater through rainwater runoff, leading to corrosion of metal components (such as bridge expansion joints and drainage pipes) and vegetation degradation. Traditional chloride salt anti-icing agents lack an effective slow-release mechanism and are rapidly lost under rainwater erosion and vehicle rolling, with an effective service life of usually less than 3 years, requiring frequent repairs and incurring high costs throughout the entire life cycle. Chloride salts have weak adhesion to asphalt, resulting in increased mixture dispersion and loss rates, which affect pavement durability.

[0003] Current technological improvements mainly focus on core-shell coating processes and slow-release complexed salt formulations: While coating chloride salts with epoxy resin or polyurethane can delay chloride salt release, the shell material relies on petroleum-based synthetic polymers, which are costly and difficult to degrade. Even if the chloride salt release cycle is extended through intercalation or complexation technology, the essential nature of chloride ion pollution cannot be avoided. Furthermore, the preparation process of intercalation materials is complex and difficult to industrialize.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material and its preparation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material and its preparation method, so as to solve the problems of environmental pollution, high cost and short functional life in the prior art.

[0006] To achieve the above objectives, this invention provides an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material and its preparation method.

[0007] An environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material comprises the following raw materials in parts by weight: 60-70 parts coarse aggregate, 20-30 parts fine aggregate, 3.5-5.8 parts mineral powder, 0.2-0.5 parts core-shell microcapsules, 4-6 parts asphalt, 3-5 parts nano-montmorillonite stabilizer, 0.5-1 part carbon nanotubes, 1-2 parts tea polyphenol derivative corrosion inhibitor, and 0.01-0.06 parts low-temperature mixing aid.

[0008] A method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, comprising the following steps: Preferably, coarse and fine aggregates are added to an intermittent asphalt mixing plant and dry-mixed for 20-40 seconds, then asphalt is added and mixed for 80-100 seconds. Finally, mineral powder, core-shell microcapsules, nano-montmorillonite stabilizer, carbon nanotubes, tea polyphenol derivative corrosion inhibitor, and low-temperature mixing aid are added in sequence, and mixing is continued for 80-100 seconds. The temperature is raised to 150-160℃, and then mixed for 3-5 minutes to obtain an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material.

[0009] Preferably, the mass ratio of the coarse aggregate, fine aggregate, mineral powder, core-shell microcapsules, nano-montmorillonite stabilizer, carbon nanotubes, tea polyphenol derivative corrosion inhibitor, and low-temperature mixing aid is 1:0.28-0.5:0.055-0.1:0.05-0.096:0.003-0.008:0.04-0.084:0.007-0.167:0.014-0.034:0.0002-0.0009.

[0010] Preferably, the low-temperature mixing aid is any one of silane coupling agent, polyether-modified siloxane, Fischer-Tropsch wax, polyethylene wax, montan wax, 1-butyl-3-methylimidazolium tetrafluoroborate, epoxidized soybean oil, lignin sulfonate, nano silica, and fatty acid amide, with fatty acid amide, Fischer-Tropsch wax, polyethylene wax, and montan wax being more preferred.

[0011] Preferably, the tea polyphenol derivative corrosion inhibitor is any one of phosphorylated tea polyphenols and tea polyphenol-zinc complex.

[0012] Preferably, the core-shell microcapsules are prepared as follows: Step S1: Add potassium acetate, calcium formate, and magnesium propionate to deionized water, heat to 50-60℃, stir at 500-600 r / min, react for 30-40 min, spray dry, and obtain composite salt particles with a particle size of 50-80 μm. Step S2: Add polycaprolactone, modified poly-N-isopropylacrylamide and octenyl succinic anhydride modified starch to supercritical CO2, pressure 9.5-10.5 MPa, heat to 43-47℃, react for 20-40 min to obtain a mixed solution. Step S3: Add the composite salt particles to the mixed solution and emulsify at high speed under 45-55 MPa for 10-20 min to form a core-shell emulsion; Step S4: Pass 5% citric acid vapor into the core-shell emulsion, heat to 50-70℃, react for 20-40 minutes, the reaction is complete, the particle size is 80-120μm, and core-shell microcapsules are obtained.

[0013] Preferably, the mass ratio of potassium acetate, calcium formate and magnesium propionate in step S1 is 2.8-3.2:1:0.8-1.2.

[0014] In step S2, the mass ratio of polycaprolactone, modified polyN-isopropylacrylamide, and octenyl succinic anhydride modified starch is 2-3:1-2:1.

[0015] Preferably, the mass ratio of the composite salt particles to the mixed solution in step S3 is 4.8-5.2:1; The ratio of the core-shell emulsion to 5% citric acid vapor in step S4 is 2-3 g: 1 mL.

[0016] Preferably, the preparation steps of the modified poly-N-isopropylacrylamide in step S2 are as follows: Step SS1: Add N-isopropylacrylamide to a methanol solution, add initiator 2,2'-azobisisobutyronitrile and chain transfer agent mercaptoethylamine hydrochloride, heat to 50-60℃, react for 7-9 hours, separate with diethyl ether, and obtain polyN-isopropylacrylamide. Step SS2: Add poly(N-isopropylacrylamide) to tetrahydrofuran solvent, stir to dissolve, prepare a 23-27 wt% solution, add triethylamine and stearoyl chloride, cool to -10-0℃, react for 3-5 h, then heat to 20-30℃, react for 3-5 h, separate with diethyl ether, and obtain modified poly(N-isopropylacrylamide).

[0017] Preferably, the mass ratio of N-isopropylacrylamide, initiator, and chain transfer agent in step SS1 is 60-75:1:2.5-5.5; In step SS2, the mass ratio of poly-N-isopropylacrylamide, triethylamine, and stearoyl chloride is 1:0.8-0.9:2.5-2.7.

[0018] The beneficial effects of this invention are: This invention provides a method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material. Through a non-chloride salt composite anti-icing system, this invention completely avoids the pollution of soil and groundwater by chloride ions and the corrosion of metal components by chloride ions, thus achieving environmental protection and conforming to the concept of green chemistry.

[0019] This invention utilizes core-shell structured microcapsules to achieve long-term release of anti-icing factors, thereby enhancing the antifreeze properties of asphalt pavements and extending their service life. Simultaneously, the nano-montmorillonite stabilizer enhances asphalt adhesion through its layered structure, reducing the rate of scattering loss.

[0020] This invention is compatible with conventional dry mixing processes for asphalt mixtures, requiring no equipment modification, thus reducing overall construction costs. It also boasts strong material compatibility, making it suitable for extreme low-temperature scenarios such as highways and airport runways, significantly reducing overall lifecycle maintenance costs.

[0021] This invention avoids chloride ion pollution through a non-chloride salt composite anti-icing system, combines core-shell structured microcapsules to release anti-icing factors for a long time and nano-montmorillonite stabilizer to enhance asphalt adhesion, and is compatible with conventional dry mixing processes for asphalt mixtures. It requires no equipment modification, significantly reduces construction and maintenance costs, and improves the road surface's frost resistance and service life. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] Example 1: A method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, comprising the following steps: S1: Add 600g of N-isopropylacrylamide to 1000mL of methanol solution, add 10g of initiator 2,2'-azobisisobutyronitrile and 25g of chain transfer agent mercaptoethylamine hydrochloride, heat to 60℃, react for 7h, separate with diethyl ether to obtain polyN-isopropylacrylamide. S2: Add 230g of poly(N-isopropylacrylamide) to 1000mL of tetrahydrofuran solvent, stir to dissolve, prepare a 23wt% solution, add 18.4g of triethylamine and 575g of stearoyl chloride, cool to -10℃, react for 5h, then heat to 30℃, react for 3h, separate with diethyl ether, and obtain modified poly(N-isopropylacrylamide); S3: Add 560g of potassium acetate, 200g of calcium formate, and 160g of magnesium propionate to 3680mL of deionized water, heat to 50℃, stir at 600r / min, react for 40min, spray dry at 180℃ inlet temperature and 80℃ outlet temperature, sieve, and obtain composite salt particles with a particle size of 50-80μm. S4: Add 200g of polycaprolactone, 100g of modified poly-N-isopropylacrylamide and 100g of octenyl succinic anhydride modified starch to supercritical CO2, pressurize to 9.5MPa, heat to 47℃, and react for 20min to obtain a mixed solution. S5: Add 480g of composite salt particles to 100g of mixed solution and emulsify at high speed at 45MPa for 20min to form a core-shell emulsion; S6: Pass 200 mL of 5% citric acid vapor into 400 g of core-shell emulsion, heat to 70 °C, react for 20 min, after the reaction is complete, solidify and sieve, the particle size is 80-120 μm, to obtain core-shell microcapsules; S7: Add 600 parts by weight of coarse aggregate and 200 parts by weight of fine aggregate to an intermittent asphalt mixing plant and dry mix for 40 seconds. Then add 40 parts by weight of asphalt and mix for 100 seconds. Finally, add 35 parts by weight of mineral powder, 2 parts by weight of core-shell microcapsules, 30 parts by weight of nano-montmorillonite stabilizer, 5 parts by weight of carbon nanotubes, 10 parts by weight of tea polyphenol-zinc complex and 0.1 parts by weight of fatty acid amide in sequence, continue mixing for 80 seconds, raise the temperature to 160°C, and mix for another 3 minutes to obtain an environmentally friendly long-lasting slow-release low freezing point asphalt pavement material.

[0024] Example 2: A method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, comprising the following steps: S1: Add 700g of N-isopropylacrylamide to 100mL of methanol solution, add 10g of initiator 2,2'-azobisisobutyronitrile and 30g of chain transfer agent mercaptoethylamine hydrochloride, heat to 50-60℃, react for 7-9h, separate with diethyl ether to obtain polyN-isopropylacrylamide. S2: Add 250g of poly(N-isopropylacrylamide) to 1000mL of tetrahydrofuran solvent, stir to dissolve, prepare a 25wt% solution, add 225g of triethylamine and 650g of stearoyl chloride, cool to -5℃, react for 4h, then heat to 25℃, react for 4h, separate with diethyl ether, and obtain modified poly(N-isopropylacrylamide); S3: Add 600g of potassium acetate, 200g of calcium formate, and 200g of magnesium propionate to 4000mL of deionized water, heat to 55℃, stir at 550r / min, react for 35min, spray dry at 180℃ inlet temperature and 80℃ outlet temperature, sieve, and obtain composite salt particles with a particle size of 50-80μm. S4: Add 250g of polycaprolactone, 150g of modified poly-N-isopropylacrylamide and 100g of octenyl succinic anhydride modified starch to supercritical CO2, pressurize to 10MPa, heat to 45℃, and react for 30min to obtain a mixed solution. S5: Add 500g of composite salt particles to 100g of mixed solution and emulsify at high speed under 50MPa for 15min to form a core-shell emulsion; S6: Pass 200 mL of 5% citric acid vapor into 500 g of core-shell emulsion, heat to 60 °C, react for 30 min, after the reaction is complete, solidify and sieve, the particle size is 80-120 μm, to obtain core-shell microcapsules; S7: Add 650 parts by weight of coarse aggregate and 250 parts by weight of fine aggregate to an intermittent asphalt mixing plant and dry mix for 30 seconds. Then add 40 parts by weight of asphalt and mix for 90 seconds. Finally, add 40 parts by weight of mineral powder, 3 parts by weight of core-shell microcapsules, 40 parts by weight of nano-montmorillonite stabilizer, 8 parts by weight of carbon nanotubes, 15 parts by weight of tea polyphenol-zinc complex and 0.5 parts by weight of fatty acid amide in sequence, continue mixing for 90 seconds, raise the temperature to 155°C, and mix for another 4 minutes to obtain an environmentally friendly long-lasting slow-release low freezing point asphalt pavement material.

[0025] Example 3: A method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, comprising the following steps: S1: Add 750g of N-isopropylacrylamide to 1000mL of methanol solution, add 10g of initiator 2,2'-azobisisobutyronitrile and 55g of chain transfer agent mercaptoethylamine hydrochloride, heat to 60℃, react for 7h, separate with diethyl ether to obtain polyN-isopropylacrylamide. S2: Add 270g of poly(N-isopropylacrylamide) to 1000mL of tetrahydrofuran solvent, stir to dissolve, prepare a 27wt% solution, add 243g of triethylamine and 729g of stearoyl chloride, cool to 0℃, react for 3h, then heat to 20℃, react for 5h, separate with diethyl ether, and obtain modified poly(N-isopropylacrylamide); S3: Add 640g of potassium acetate, 200g of calcium formate and 240g of magnesium propionate to 4320mL of deionized water, heat to 60℃, stir at 600r / min, react for 30min, spray dry at 180℃ inlet temperature and 80℃ outlet temperature, sieve, and obtain composite salt particles with a particle size of 50-80μm. S4: Add 300g of polycaprolactone, 200g of modified poly-N-isopropylacrylamide and 100g of octenyl succinic anhydride modified starch to supercritical CO2, pressurize to 10.5MPa, heat to 47℃, react for 20min to obtain a mixed solution. S5: Add 520g of composite salt particles to 100g of mixed solution and emulsify at high speed at 55MPa for 10min to form a core-shell emulsion; S6: Pass 200 mL of 5% citric acid vapor into 600 g of core-shell emulsion, heat to 50 °C, react for 40 min, after the reaction is complete, solidify and sieve, the particle size is 80-120 μm, to obtain core-shell microcapsules; S7: Add 700 parts by weight of coarse aggregate and 300 parts by weight of fine aggregate to an intermittent asphalt mixing plant and dry mix for 40 seconds. Then add 60 parts by weight of asphalt and mix for 80 seconds. Finally, add 58 parts by weight of mineral powder, 5 parts by weight of core-shell microcapsules, 50 parts by weight of nano-montmorillonite stabilizer, 10 parts by weight of carbon nanotubes, 20 parts by weight of tea polyphenol-zinc complex and 0.6 parts by weight of fatty acid amide in sequence, continue mixing for 80 seconds, raise the temperature to 160°C, and mix for another 5 minutes to obtain an environmentally friendly long-lasting slow-release low freezing point asphalt pavement material.

[0026] Comparative Example 1: Compared with Example 1, this comparative example did not add nano-montmorillonite stabilizer in the preparation process of environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material. All other steps and parameters were the same, and will not be repeated in this comparative example. Finally, environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material was obtained.

[0027] Comparative Example 2: Add 600 parts by weight of coarse aggregate and 200 parts by weight of fine aggregate to an intermittent asphalt mixing plant and dry mix for 40 seconds. Then add 40 parts by weight of asphalt and mix for 100 seconds. Finally, add 35 parts by weight of mineral powder, 2 parts by weight of calcium chloride, 30 parts by weight of nano-montmorillonite stabilizer, 5 parts by weight of carbon nanotubes, 10 parts by weight of benzotriazole corrosion inhibitor and 0.1 parts by weight of fatty acid amide in sequence, continue mixing for 80 seconds, raise the temperature to 160°C, and mix for another 3 minutes to obtain an environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material.

[0028] Comparative Example 3: Compared with Example 1, this comparative example directly mixes composite salt particles with asphalt, and the remaining steps and parameters are the same. This comparative example will not be repeated here. Finally, an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material is obtained.

[0029] Comparative Example 4: This comparative example differs from Example 1 only in that the "mixed solution" is replaced with "polyurethane emulsion". All other steps and parameters are the same, and will not be repeated here. The final result is an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material.

[0030] Comparative Example 5 Compared with Example 1, this comparative example only replaces "the mass ratio of potassium acetate, calcium formate and magnesium propionate is 2.8-3.2:1:0.8-1.2" with "the mass ratio of potassium acetate, calcium formate and magnesium propionate is 1:1:1". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, an environmentally friendly long-lasting slow-release low freezing point asphalt pavement material is obtained.

[0031] Comparative Example 6 Compared with Example 1, this comparative example did not add modified poly-N-isopropylacrylamide in the preparation process of the core-shell microcapsules. All other steps and parameters were the same, and will not be repeated here. The final product was an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material.

[0032] Comparative Example 7 Compared with Example 1, this comparative example did not add carbon nanotubes in the preparation process of the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material. All other steps and parameters were the same, and will not be repeated here. The final result was an environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material.

[0033] Preparation of asphalt pavement test blocks Substrate preparation: Clean and level the cement-stabilized gravel substrate to ensure that there are no loose particles on the surface.

[0034] The asphalt pavement blocks are produced by using a paver to spread the asphalt at a uniform speed, with a paving temperature of 150-160℃ and a thickness of 4cm. The initial compaction temperature of the steel wheel roller is 150℃, and the final static compaction temperature of the steel wheel roller is 90℃. The asphalt is then allowed to cool naturally to 50℃ to obtain environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement blocks.

[0035] Performance testing: Porosity testing The porosity of the core-shell microcapsules of Examples 1-3, Comparative Examples 4 and 6 was determined using the deionized water substitution method.

[0036] The core-shell microcapsules of Examples 1-3, Comparative Examples 4 and 6 were dried, weighed, and recorded as m0. Their volume V0 was measured, and the density of deionized water was recorded as ρ. Low temperature treatment: Cool down to -10℃, let the microcapsules stand for 10 minutes, then immerse them in deionized water for 10 minutes, weigh the wet weight, repeat three or more times, take the average value, and record it as m1; High temperature treatment: Heat to 40℃, remove deionized water, dry, soak in deionized water again, put in for 10 minutes, weigh the wet weight, repeat three or more times, take the average value, and record it as m2; Porosity P is calculated as follows:

[0037] Microcapsule mechanical strength testing: Mechanical breakage rate determination: The core-shell microcapsules of Examples 1-3, Comparative Examples 4 and 6 were placed in the 24 wells of a fixed re-gyro oscillator, and the breakage rate of the microcapsules was determined within 5 hours.

[0038] Determination of compressive modulus: Measure the diameter of the microcapsules, set the loading speed of the AG-10TA universal tester to 2 mm / min, the load range to 0.1 N and the specified compression amount, and obtain the compressive modulus of the specified deformation on the deformation-compression modulus graph; repeat the above steps 5 times and calculate the average value.

[0039] Table 1 project <![CDATA[P -10℃ (%)]]> <![CDATA[P 40℃ (%)]]> <![CDATA[P -10℃ -P 40℃ ]]> Breakage rate (%) Compression modulus (kPa) Example 1 24 15 9 31 51.2 Example 2 25 17 8 32 52.1 Example 3 24 16 8 30 51.8 Comparative Example 4 22 22 0 30 50.8 Comparative Example 6 19 19 0 51 43.2 Freezing point detection Q2000 Differential Calorimeter (TA Instruments, Inc., USA) Weigh 5 mg of each of the asphalt pavement material samples from Examples 1-3 and Comparative Examples 1-7. Place the sample in a crucible, press and seal it, cool it from 25℃ to -50℃ at a cooling rate of 5℃ / min, hold it at that temperature for 5min, and then heat it to 10℃ at a heating rate of 1℃ / min with a nitrogen flow rate of 50mL / min. Record the data for each heating stage.

[0040] Snowmelt rate detection Asphalt pavement test blocks from Examples 1-3 and Comparative Examples 1-7 were placed in a low-temperature environment chamber, the pavement was cleaned and wiped with anhydrous ethanol, cooled to -20°C, and kept at a constant temperature for 24 hours. Take out the road test block, spray deionized water evenly onto the road surface with a sprayer to form a water film with a thickness of about 0.1 mm, and then put the road test block into a low temperature environment chamber and let it stand for 1 hour to form an ice layer. Turn on the low-temperature environment chamber and fluorescent lamp (40W, irradiance 25W / m²). 3 Monitor the surface temperature of the road test block until the ice layer completely melts, and record the time from the start of the test to complete melting (t, unit: min). Calculate the snowmelt rate R:

[0041] h --- Initial ice thickness, mm; t --- complete melting time, in minutes.

[0042] Chloride ion release rate detection According to GB 5085.3-2007, asphalt pavement materials from Examples 1-3 and Comparative Examples 1-7 were used to prepare samples of 10cm × 10cm × 1cm. The exposed area was calculated and denoted as A (cm²). 2 ); The sample surface was washed three times with deionized water and dried at room temperature for 24 hours. Deionized water was used as the extraction medium, the pH was adjusted to 6.5-7.5, the temperature was 23±2℃, the sample was immersed in deionized water, sealed, and placed on a shaker at 23±2℃ for 60 rpm for 30 days. Samples were taken periodically, and an equal amount of deionized water was added after each sample was taken. Filter the extract, detect it by ion chromatography (IC), record the peak area, and calculate the chloride ion concentration C (mg / L). Chloride ion release rate calculation:

[0043] C --- Chloride ion concentration of the extract (mg / L); V---Volume of extraction liquid (L); A---Exposed surface area of ​​the specimen (cm²); t---Extraction time (days).

[0044] Table 2 project Freezing point (°C) R(mm / min) Chloride ion release rate (mg / (cm²·year)) Example 1 -42 0.60 0.01 Example 2 -43 0.65 0.02 Example 3 -41 0.58 0.01 Comparative Example 1 -40 0.55 0.01 Comparative Example 2 -25 0.30 0.85 Comparative Example 3 -35 0.20 0.01 Comparative Example 4 -38 0.40 0.01 Comparative Example 5 -30 0.35 0.01 Comparative Example 6 -38 0.25 0.01 Comparative Example 7 -42 0.50 0.01 High-temperature rutting resistance testing According to JTG E20-2011 standard, road test blocks of Examples 1-3 and Comparative Examples 1-7, with a size of 300mm×300mm×50mm, were placed in a constant temperature chamber at 60±0.5℃ and kept at that temperature for 6 hours. Remove the test block and place it on the base of the rut tester. Apply a wheel pressure of 0.7 MPa, a temperature of 60℃, and a travel speed of 42 times / min. Start the equipment, test for 45 minutes (or rut depth 25 mm), stop the test, and record the rut deformation curve; Formula for calculating dynamic stability (DS) of ruts:

[0045] N----Number of times (rolling times) within the 45-minute test period; d1----Rut depth 45 minutes after the start of the test, in mm; d2----Rut depth 60 minutes after the start of the test, in mm; t------Experiment time, in minutes.

[0046] Water stability In accordance with ASTM D4867, two cylindrical specimens with a diameter of 100 mm and a height of 63.5 mm were prepared using the asphalt pavement materials of Examples 1-3 and Comparative Examples 1-7. The specimens were divided into a freeze-thaw group (Group A) and a non-freeze-thaw group (Group B). Group A: Vacuum saturation (vacuum degree ≥30kPa, 15min), immersion in water for 30min, then freezing at -18±2℃ for 16h, followed by thawing in a 60±1℃ water bath for 24h, cycled once; Group B: Vacuum saturation only, without freeze-thaw cycle.

[0047] Place in a 25℃ water bath and keep warm for 2 hours. After the warming process is complete, use a splitting fracture tester (model) at a rate of 50 mm / min and record the maximum failure load P. A and P B ; Strength ratio calculation:

[0048] Anti-slip test According to ASTM C131, 5000g of asphalt pavement materials from Examples 1-3 and Comparative Examples 1-7 were taken respectively. After sieving, particles with a diameter ≥4.75mm were retained. They were placed in an oven at 60℃ and dried for 12 hours. They were weighed and recorded as M1. Place the asphalt pavement material and 12 steel balls (47mm in diameter, total mass 5000g±50g) into the drum of the Los Angeles abrasion mill. Rotate at 30-33 rpm for 500 r, then remove, sieve through a 1.7mm sieve, weigh, and record as M2. Formula for calculating scattering loss rate:

[0049] Table 3 project DS (times / mm) Strength ratio (%) Scattering loss rate (%) Example 1 3800 89 2.5 Example 2 3850 90 2.3 Example 3 3750 88 2.7 Comparative Example 1 2800 75 8.2 Comparative Example 2 3200 80 4.5 Comparative Example 3 2500 68 12.1 Comparative Example 4 3400 78 3.8 Comparative Example 5 3000 72 6.5 Comparative Example 6 3100 70 9.0 Comparative Example 7 3500 85 4.0 Data Analysis: As can be seen from Tables 1-3, the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material prepared by the present invention has better environmental protection, long-lasting slow-release anti-icing ability, high temperature stability, anti-scattering performance and process compatibility. In contrast, Comparative Example 1, which did not add nano-montmorillonite, had a significantly lower scattering loss rate and rutting dynamic stability than Example 1. This is because nano-montmorillonite has a layered structure, which can enhance asphalt adhesion. However, the lack of nano-montmorillonite in Comparative Example 1 resulted in insufficient asphalt adhesion, making the aggregate easy to detach and reducing its resistance to deformation at high temperatures. Comparative Example 2, due to the use of calcium chloride, had a chloride ion release rate and freezing point much higher than Example 1. This is because calcium chloride in Comparative Example 2 has no slow-release mechanism, and the chloride ions on calcium chloride will cause serious pollution to the soil and corrosion of metal structures. Furthermore, the anti-icing factor of calcium chloride is rapidly lost under the erosion of rainwater and the crushing action of passing vehicles. Comparative Example 3 shows that the snow melting rate and freezing point are extremely low due to the direct mixing of composite salt particles. This is because the composite salt particles lack core-shell structure protection and have poor compatibility with asphalt, resulting in excessively rapid salt release. Meanwhile, the slow-release mechanism of the core-shell microcapsules is the core of long-term antifreeze. In Comparative Example 4, the microcapsule porosity and compressive modulus were lower than those in Example 1 because polyurethane emulsion replaced the mixed solution. This is because Example 1 contained long-chain acyl chloride-modified polyN-isopropylacrylamide. The long-chain groups increased the crosslinking degree of the internal structure of the microcapsule, which improved the mechanical strength of the microcapsule. However, the polyurethane had poor degradability, low sustained-release efficiency, and poor long-lasting anti-icing effect. In Comparative Example 5, the imbalance of the compound salt ratio led to a weakening of the synergistic effect between the anti-icing factors, which reduced the salt release efficiency inside the microcapsules and affected the anti-icing effect. Comparative Example 6, due to the lack of modified poly-N-isopropylacrylamide, resulted in insufficient shell flexibility of the microcapsules and weak shear resistance. Meanwhile, modified poly-N-isopropylacrylamide can change the porosity of the microcapsules according to changes in ambient temperature, thereby regulating the release rate of the anti-icing factor and increasing the service life. Comparative Example 7 had lower rutting dynamic stability than Example 1 because no carbon nanotubes were added. This was because the lack of carbon nanotubes led to a loose asphalt network structure, which reduced the high-temperature rutting resistance. At the same time, the photothermal effect of Comparative Example 7 was weakened, resulting in a snow melting rate that was slightly lower than that of Example 1. The materials and processes of this invention ensure that, after 10 years of service, the freezing point of the road surface remains ≤-35℃, the snow melting rate decreases by ≤10%, there is zero chloride ion release, and the soil pH value in vegetated areas does not change significantly. The core-shell microcapsules, tea polyphenol derivatives, and nano-montmorillonite can directly replace mineral powder, are compatible with conventional asphalt mixing plant processes, require no equipment modification, and the core-shell slow-release structure forms a gradient porous structure through citric acid vapor crosslinking, controlling the phased release of anti-icing factors.

[0050] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0051] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, characterized in that, The raw materials include the following parts by weight: 60-70 parts coarse aggregate, 20-30 parts fine aggregate, 3.5-5.8 parts mineral powder, 0.2-0.5 parts core-shell microcapsules, 4-6 parts asphalt, 3-5 parts nano-montmorillonite stabilizer, 0.5-1 part carbon nanotubes, 1-2 parts tea polyphenol derivative corrosion inhibitor, and 0.01-0.06 parts low-temperature mixing aid.

2. A method for preparing an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material, characterized in that, The preparation steps are as follows: Add coarse and fine aggregates to an intermittent asphalt mixing plant and dry mix for 20-40 seconds. Then add asphalt and mix for 80-100 seconds. Finally, add mineral powder, core-shell microcapsules, nano-montmorillonite stabilizer, carbon nanotubes, tea polyphenol derivative corrosion inhibitor, and low-temperature mixing aid in sequence. Continue mixing for 80-100 seconds, raise the temperature to 150-160℃, and mix for another 3-5 minutes to obtain an environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material.

3. The preparation method of the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material according to claim 2, characterized in that, The mass ratio of the coarse aggregate, fine aggregate, asphalt, mineral powder, core-shell microcapsules, nano-montmorillonite stabilizer, carbon nanotubes, tea polyphenol derivative corrosion inhibitor, and low-temperature mixing aid is 1:0.28-0.5:0.055-0.1:0.05-0.096:0.003-0.008:0.04-0.084:0.007-0.167:0.014-0.034:0.0002-0.0009.

4. The preparation method of the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material according to claim 2, characterized in that, The low-temperature mixing aid is any one of the following: silane coupling agent, polyether-modified siloxane, Fischer-Tropsch wax, polyethylene wax, montan wax, 1-butyl-3-methylimidazolium tetrafluoroborate, epoxidized soybean oil, lignin sulfonate, nano silica, and fatty acid amide, preferably fatty acid amide, Fischer-Tropsch wax, polyethylene wax, and montan wax.

5. The preparation method of the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material according to claim 2, characterized in that, The corrosion inhibitor derived from tea polyphenols is either phosphorylated tea polyphenols or tea polyphenol-zinc complex.

6. The method for preparing the environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material according to claim 2, characterized in that, The core-shell microcapsules are prepared as follows: Step S1: Add potassium acetate, calcium formate, and magnesium propionate to deionized water, heat to 50-60℃, stir at 500-600 r / min, react for 30-40 min, spray dry, and obtain composite salt particles with a particle size of 50-80 μm. Step S2: Add polycaprolactone, modified poly-N-isopropylacrylamide and octenyl succinic anhydride modified starch to supercritical CO2, pressure 9.5-10.5 MPa, heat to 43-47℃, react for 20-40 min to obtain a mixed solution. Step S3: Add the composite salt particles to the mixed solution and emulsify at high speed under 45-55 MPa for 10-20 min to form a core-shell emulsion; Step S4: Pass 5% citric acid vapor into the core-shell emulsion, heat to 50-70℃, react for 20-40 minutes, the reaction is complete, the particle size is 80-120μm, and core-shell microcapsules are obtained.

7. The preparation method of the environmentally friendly long-lasting slow-release low-freezing-point asphalt pavement material according to claim 6, characterized in that, The mass ratio of potassium acetate, calcium formate, and magnesium propionate in step S1 is 2.8-3.2:1:0.8-1.2; In step S2, the mass ratio of polycaprolactone, modified poly-N-isopropylacrylamide, and octenyl succinic anhydride modified starch is 2-3:1-2:

1.

8. The method for preparing the environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material according to claim 6, characterized in that, The mass ratio of the composite salt particles to the mixed solution in step S3 is 4.8-5.2:1; The ratio of the core-shell emulsion to 5% citric acid vapor in step S4 is 2-3 g: 1 mL.

9. The method for preparing the environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material according to claim 6, characterized in that, The preparation steps of the modified poly-N-isopropylacrylamide in step S2 are as follows: Step SS1: Add N-isopropylacrylamide to a methanol solution, add initiator 2,2'-azobisisobutyronitrile and chain transfer agent mercaptoethylamine hydrochloride, heat to 50-60℃, react for 7-9 hours, separate with diethyl ether, and obtain polyN-isopropylacrylamide. Step SS2: Add poly(N-isopropylacrylamide) to tetrahydrofuran solvent, stir to dissolve, prepare a 23-27 wt% solution, add triethylamine and stearoyl chloride, cool to -10-0℃, react for 3-5 h, then heat to 20-30℃, react for 3-5 h, separate with diethyl ether, and obtain modified poly(N-isopropylacrylamide).

10. The method for preparing the environmentally friendly, long-lasting, slow-release, low-freezing-point asphalt pavement material according to claim 9, characterized in that, The mass ratio of N-isopropylacrylamide, initiator, and chain transfer agent in step SS1 is 60-75:1:2.5-5.5; In step SS2, the mass ratio of poly-N-isopropylacrylamide, triethylamine, and stearoyl chloride is 1:0.8-0.9:2.5-2.7.

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