A high-temperature resistant warm mix rubber asphalt mixture, its preparation method and application

Abstract

The present invention relates to the technical field of road engineering construction, and specifically discloses a high-temperature resistant warm mix rubber asphalt mixture, its preparation method and application. The high-temperature resistant warm mix rubber asphalt mixture includes coarse aggregate, fine aggregate, palmitic acid-lauric acid / vermiculite phase change material, warm mix agent, waste rubber powder and matrix asphalt. In the present invention, the palmitic acid-lauric acid / vermiculite phase change material is added to the asphalt mixture, effectively improving the problem of unstable performance of the asphalt mixture in a high-temperature environment; and the present invention also improves the asphalt aggregate, obtaining a coarse aggregate with a core-shell structure with optical fiber waste particles as the core layer and a rubber elastomer as the shell layer, effectively improving the rutting resistance of the asphalt mixture. The present invention effectively solves the problem of unstable performance of the asphalt mixture in the prior art in a high-temperature environment, and provides a new design idea for asphalt mixtures used in a high-temperature environment.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering construction, and specifically discloses a high-temperature resistant warm-mix rubber asphalt mixture, a preparation method thereof, and applications thereof. Background Art

[0002] In recent years, asphalt pavement has become the predominant surface material for high-grade roads in my country due to its excellent installation quality, low construction costs, and easy maintenance. Currently, over 90% of highways under construction or reconstruction utilize asphalt pavement. However, asphalt is a black, heat-absorbing material with a high absorption rate of solar radiation. Under continuous exposure to sunlight, the internal temperature of asphalt pavements can easily exceed their serviceable temperature, causing thermal stability defects such as rutting and shoving. Furthermore, asphalt pavements exposed to high temperatures release large amounts of asphalt volatiles, which pollute the environment. In particular, urban asphalt pavements release heat continuously at high temperatures, causing surrounding temperatures to rise and creating the urban heat island effect. Therefore, research on asphalt materials has become a key topic in road construction.

[0003] Phase change materials (PCMs) are substances that change form with temperature and provide latent heat, storing or releasing heat in the form of latent heat during the phase change process. When the material's phase change temperature is reached, the energy storage and heat release process is triggered. This energy storage and heat release significantly reduce the temperature fluctuations of the material, thus saving energy and reducing emissions and improving the temperature distribution of pavement structures, thereby enhancing structural strength and durability. Based on the properties of PCMs, prior art reports have reported the application of PCMs in asphalt mixtures to improve the performance degradation of asphalt mixtures at high or low temperatures.

[0004] However, the direct application of phase change materials in asphalt mixtures can affect the lifespan and stability of asphalt pavements. Therefore, microencapsulation or fixed-shape adsorption treatments are often required. Microencapsulated phase change materials are prone to leakage, while fixed-shape adsorption forms can lead to stability issues, such as insufficient or excessive adsorption leading to leakage. Therefore, improving the performance of asphalt mixtures in high-temperature environments by adding phase change materials still has a number of drawbacks.

[0005] Based on this, developing an asphalt mixture with good compatibility and stable performance at high temperatures is of great significance to the field of road construction. Summary of the Invention

[0006] To address the unstable performance of existing asphalt mixtures in high-temperature environments, the present invention provides a high-temperature-resistant warm-mix rubber asphalt mixture. This invention incorporates a palmitic acid-lauric acid / vermiculite phase change material into the asphalt mixture, which undergoes a phase change below the asphalt softening point. This stabilizes the temperature of pavement paved with this asphalt mixture below the asphalt softening point for extended periods, effectively improving the high-temperature performance of the asphalt mixture.

[0007] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0008] In the first aspect of the present invention, a high-temperature resistant warm mix rubber asphalt mixture is provided, which comprises the following raw material components in parts by mass: 15 parts - 25 parts of coarse aggregate, 10 parts - 15 parts of fine aggregate, 3 parts - 6 parts of palmitic acid-lauric acid / vermiculite phase change material, 5 - 10 parts of warm mix agent, 15 parts - 20 parts of waste rubber powder, and 65 parts - 70 parts of matrix asphalt.

[0009] Preferably, the coarse aggregate has a core-shell structure, wherein the core layer material is optical fiber waste particles, and the shell layer material is ethylene propylene diene monomer-carboxy nitrile butadiene rubber polymer.

[0010] Compared with the prior art, a novel phase change material is added to the asphalt mixture in the present invention. It is prepared by using vermiculite as a supporting material to adsorb the palmitic acid-lauric acid binary eutectic phase change material. The phase change of the palmitic acid-lauric acid / vermiculite phase change material can absorb the energy radiated by the sun to the asphalt pavement, reduce the heat diffusion rate and heating rate of the asphalt pavement, which is equivalent to indirectly increasing the thermal resistance of the asphalt pavement, thereby effectively reducing the surface temperature of the asphalt pavement material at high temperature and stabilizing it at a constant level. The phase change temperature of the palmitic acid-lauric acid / vermiculite phase change material selected in the present invention is lower than the softening point temperature of the asphalt, and the phase change enthalpy is larger, which can absorb more heat and improve the cooling rate of the asphalt mixture. Moreover, this phase change material does not have a leakage problem, and can effectively improve the problem of unstable performance of the asphalt mixture at high temperature.

[0011] Meanwhile, the present invention improves the asphalt aggregate. During the production process of optical fibers, a large amount of optical fiber waste will be generated due to non-standard operations. At present, a large amount of optical fiber waste is disposed of by landfill. However, the main material of optical fiber waste is quartz, and some are doped with rare earth metals, and directly landfilling is not friendly to the environment. The present invention uses optical fiber waste as the internal structure of the coarse aggregate, and coats a layer of polymer rubber material on its surface to obtain an aggregate with a soft exterior and a rigid interior. The optical fiber waste has high hardness but is brittle. Directly doping it into the asphalt material will result in a relatively high brittleness of the asphalt mixture, and this characteristic will be exacerbated at low temperatures. Based on this, the present invention coats a layer of elastomer rubber on its surface to make up for the excessive brittleness of the optical fiber waste by using the toughness and elasticity of the rubber, thereby improving the rutting resistance of the asphalt mixture and alleviating the treatment pressure of the optical fiber waste. Moreover, ethylene propylene diene monomer and carboxy nitrile butadiene rubber have good heat resistance and wear resistance, further improving the service life of the asphalt mixture in a relatively high temperature environment.

[0012] Preferably, the preparation method of the palmitic acid-lauric acid / vermiculite phase change material comprises the following steps:

[0013] S1. Heat the dry vermiculite to 250°C - 300°C in one step, keep it warm for the first time, then heat it to 450°C - 500°C in the second step, keep it warm for the second time, and then cool it down to obtain the vermiculite matrix.

[0014] S2. Under an inert atmosphere, mix palmitic acid, lauric acid with the vermiculite matrix, keep it warm at 75°C - 90°C for 1h - 2h, filter and dry to obtain the palmitic acid - lauric acid / vermiculite phase change material.

[0015] The structure of vermiculite is a layered silicon - oxygen framework structure. There is a water molecule layer between layers. When heated at high temperature, the water molecules turn into water vapor to generate pressure, causing the layer spacing to expand and the structure to become loose and porous, improving the adsorption capacity of vermiculite. Palmitic acid and lauric acid, as binary eutectic phase change materials, can be adsorbed in the porous vermiculite material to the greatest extent at a certain temperature, thus obtaining a composite phase change material.

[0016] Further preferably, in S1, both the first - stage heating and the second - stage heating adopt the programmed - heating method. Among them, the heating rate of the first - stage heating is 5°C / min - 10°C / min, and the heating rate of the second - stage heating is 4°C / min - 6°C / min.

[0017] Further preferably, in S1, the cooling adopts the programmed - cooling method, and the cooling rate is 10°C / min - 20°C / min.

[0018] Further preferably, in S1, the time for the first - stage heat preservation is 30min - 60min.

[0019] Further preferably, in S1, the time for the second - stage heat preservation is 1h - 2h.

[0020] Further preferably, in S2, the mass ratio of palmitic acid, lauric acid to the vermiculite matrix is 0.5:0.5:1 - 0.8:1.5:2.

[0021] Preferably, the preparation method of the coarse aggregate includes the following steps:

[0022] Step a. Blend ethylene - propylene - diene monomer rubber, carboxyl - nitrile rubber and organic additives at 70°C - 80°C to obtain a blended rubber compound.

[0023] Step b. Add a vulcanizing agent and an organic solvent to the blended rubber compound, mix evenly to obtain a mixed rubber slurry.

[0024] Step c. Immerse the crushed optical - fiber waste particles into the mixed rubber slurry, screen and dry to obtain impregnated particles.

[0025] Step d. Repeat the operation of step c 2 - 4 times to obtain the coarse aggregate.

[0026] This invention uses waste optical fiber particles as the core layer of the coarse aggregate, leveraging their substantial hardness to provide a skeletal support for the coarse aggregate, thereby improving the asphalt mixture's rutting resistance. However, due to the brittleness of waste optical fiber, using it directly increases the brittleness of the asphalt mixture, making it unsuitable for use in low-temperature environments. Therefore, the present invention coats the waste optical fiber particles with a layer of elastomeric rubber, mitigating their brittleness while improving the asphalt mixture's ductility and elasticity.

[0027] Further preferably, the mass ratio of the EPDM rubber to the carboxylated nitrile rubber is 1-1:1-2.

[0028] Further preferably, the mass ratio of the organic additive to the total mass of the EPDM rubber and the carboxylated nitrile rubber is 0.03:1-0.05:1.

[0029] Further preferably, the organic auxiliary agent comprises the following components in percentage by weight: 30%-35% of an accelerator, 25%-30% of an oxidant and the remainder of an antioxidant.

[0030] More preferably, the vulcanizing agent is sulfur.

[0031] More preferably, the organic solvent is toluene.

[0032] Further preferably, the mass ratio of the blended rubber, the vulcanizing agent and the organic solvent is 80:2:120-100:4:150.

[0033] Further preferably, in step a, the blending time is 30 min-50 min.

[0034] Further preferably, the particle size of the optical fiber waste particles is 0.5 mm-1.5 mm.

[0035] Preferably, the fine aggregate comprises the following components in percentage by mass: 70%-85% of quartz sand, 5%-10% of ceramic powder and the balance of slag powder.

[0036] Preferably, the warming agent is any one of microcrystalline cellulose or polyethylene wax.

[0037] Preferably, the particle size of the waste rubber powder is 0.5 mm-1 mm.

[0038] The second aspect of the present invention provides a method for preparing the high-temperature resistant warm mix rubber asphalt mixture, comprising the following steps:

[0039] Step 1: Weigh coarse aggregate and fine aggregate according to the designed proportion to obtain mixed aggregate;

[0040] Step 2: Heat the matrix asphalt to 120°C - 150°C, and successively add the mixed aggregate, warm mix additive, waste rubber powder, and palmitic acid - lauric acid / vermiculite phase change material, and mix evenly to obtain the high - temperature resistant warm mix rubber asphalt mixture.

[0041] In the third aspect of the present invention, there is provided the application of the high - temperature resistant warm mix rubber asphalt mixture in the field of road engineering construction.

[0042] In summary, the present invention provides a high - temperature resistant warm mix rubber asphalt mixture and its preparation method. Using optical fiber waste particles with a rubber outer layer as the coarse aggregate and palmitic acid - lauric acid / vermiculite material as the phase change material, while improving the rutting resistance of the asphalt mixture, it also enhances its cooling rate in a high - temperature environment, effectively solving the problem of unstable performance of asphalt mixtures in the prior art under high - temperature environments, and providing a new design idea for asphalt pavement materials used in high - temperature environments. Specific Embodiments

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Example 1

[0045] This example provides a palmitic acid - lauric acid / vermiculite phase change material, which specifically includes the following steps:

[0046] S1: Heat 500 g of dry vermiculite at a heating rate of 10°C / min to 270°C at one time, keep it warm for 40 min, then heat it to 480°C at a heating rate of 5°C / min for the second time, keep it warm for 1.5 h, and then cool it to room temperature at a cooling rate of 15°C / min to obtain 487 g of vermiculite matrix;

[0047] S2: Under an inert atmosphere, mix 160 g of palmitic acid, 235 g of lauric acid with the vermiculite matrix, impregnate at 80°C for 2 h, filter, and dry at 80°C for 4 h to obtain the palmitic acid - lauric acid / vermiculite phase change material.

[0048] Example 2

[0049] This example provides a palmitic acid - lauric acid / vermiculite phase change material, which specifically includes the following steps:

[0050] S1, 500g of dried vermiculite was heated to 256°C at a heating rate of 8°C / min, kept warm for 60min, then heated to 466°C at a heating rate of 6°C / min for a second time, kept warm for 2h, and then cooled to room temperature at a cooling rate of 20°C / min to obtain 473g of vermiculite matrix;

[0051] S2. Under an inert atmosphere, 160 g of palmitic acid and 235 g of lauric acid were mixed with the vermiculite matrix, immersed at 80° C. for 2 h, filtered, and dried at 85° C. for 4 h to obtain the palmitic acid-lauric acid / vermiculite phase change material.

[0052] Example 3

[0053] This embodiment provides a palmitic acid-lauric acid / vermiculite phase change material, which specifically includes the following steps:

[0054] S1, 500g of dried vermiculite was heated to 300°C at a heating rate of 5°C / min, kept warm for 30min, then heated to 500°C at a heating rate of 4°C / min for a second time, kept warm for 1h, and then cooled to room temperature at a cooling rate of 20°C / min to obtain 471g of vermiculite matrix;

[0055] S2. Under an inert atmosphere, 240 g of palmitic acid and 240 g of lauric acid were mixed with the vermiculite matrix, immersed at 80° C. for 2 h, filtered, and dried at 80° C. for 4 h to obtain the palmitic acid-lauric acid / vermiculite phase change material.

[0056] Example 4

[0057] This embodiment provides a high-temperature resistant warm-mix rubber asphalt mixture, which uses the palmitic acid-lauric acid / vermiculite phase change material provided in Example 1 and specifically includes the following contents.

[0058] The high-temperature resistant warm-mix rubber asphalt mixture comprises the following raw material components in parts by mass: 20 parts of coarse aggregate, 13 parts of fine aggregate, 4 parts of palmitic acid-lauric acid / vermiculite phase change material, 8 parts of polyethylene wax, 17 parts of waste rubber powder and 68 parts of matrix asphalt.

[0059] The preparation method of the high temperature resistant warm mix rubber asphalt mixture comprises the following steps:

[0060] Step 1: Weigh coarse aggregate and fine aggregate according to the designed proportion to obtain mixed aggregate;

[0061] Step 2: Heat the base asphalt to 140° C., add the mixed aggregate, polyethylene wax, waste rubber powder and palmitic acid-lauric acid / vermiculite phase change material in sequence, mix them evenly, and obtain the high-temperature resistant warm-mix rubber asphalt mixture.

[0062] The method for preparing the coarse aggregate comprises the following steps:

[0063] Step a: Blend 1 kg of ethylene propylene diene monomer rubber, 1.5 kg of carboxylated nitrile butadiene rubber and organic additives at 80 °C for 50 min to obtain a blended rubber compound.

[0064] Step b: Add 75 g of sulfur and 3.5 kg of toluene to the blended rubber compound, mix evenly to obtain a mixed rubber slurry.

[0065] Step c: Immerse optical fiber waste particles with a particle size of 3 mm into the mixed rubber slurry, screen, and dry to obtain impregnated rubber particles.

[0066] Step d: Repeat the operation of Step c three times to obtain coarse aggregate.

[0067] Among them, the organic additives include components with the following mass percentages: 32% of accelerator TMTD, 30% of antioxidant, and 38% of antioxidant 4020.

[0068] The fine aggregate includes components with the following mass percentages: 75% of quartz sand, 8% of ceramic powder, and 17% of slag micro powder.

[0069] The particle size of the waste rubber powder is 0.6 mm.

[0070] Example 5

[0071] This example provides a high-temperature warm-mix rubber asphalt mixture, using the palmitic acid-lauric acid / vermiculite phase change material provided in Example 2, and specifically includes the following content.

[0072] The high-temperature warm-mix rubber asphalt mixture includes the following raw material components in parts by mass: 25 parts of coarse aggregate, 14 parts of fine aggregate, 5 parts of palmitic acid-lauric acid / vermiculite phase change material, 10 parts of microcrystalline cellulose, 15 parts of waste rubber powder, and 70 parts of matrix asphalt.

[0073] The preparation method of the high-temperature warm-mix rubber asphalt mixture includes the following steps:

[0074] Step one: Weigh the coarse aggregate and fine aggregate according to the designed ratio to obtain a mixed aggregate.

[0075] Step two: Heat the matrix asphalt to 135 °C, and successively add the mixed aggregate, microcrystalline cellulose, waste rubber powder, and palmitic acid-lauric acid / vermiculite phase change material, and mix evenly to obtain the high-temperature warm-mix rubber asphalt mixture.

[0076] Among them, the preparation method of the coarse aggregate includes the following content:

[0077] Step a: Blend 1 kg of ethylene propylene diene monomer rubber, 1.5 kg of carboxylated nitrile butadiene rubber and organic additives at 80 °C for 50 min to obtain a blended rubber compound.

[0078] Step b: Add 75 g of sulfur and 3.5 kg of toluene to the blend compound, mix evenly to obtain a mixed glue slurry.

[0079] Step c: Immerse optical fiber waste particles with a particle size of 3 mm into the mixed glue slurry, sieve, and dry to obtain impregnated particles.

[0080] Step d: Repeat the operation in Step c three times to obtain coarse aggregate.

[0081] Among them, the organic auxiliary agent includes components with the following mass percentages: 30% of accelerator TMTD, 28% of antioxidant, and 42% of antioxidant 4020.

[0082] The fine aggregate includes components with the following mass percentages: 85% of quartz sand, 10% of ceramic powder, and 5% of slag micro-powder.

[0083] The particle size of the waste rubber powder is 1 mm.

[0084] Example 6

[0085] This example provides a high-temperature warm-mix rubber asphalt mixture, using the palmitic acid-lauric acid / vermiculite phase change material provided in Example 3, and specifically includes the following content.

[0086] The high-temperature warm-mix rubber asphalt mixture includes the following raw material components in parts by mass: 18 parts of coarse aggregate, 12 parts of fine aggregate, 5 parts of palmitic acid-lauric acid / vermiculite phase change material, 8 parts of microcrystalline cellulose, 15 parts of waste rubber powder, and 66 parts of matrix asphalt.

[0087] The preparation method of the high-temperature warm-mix rubber asphalt mixture includes the following steps:

[0088] Step 1: Weigh the coarse aggregate and the fine aggregate according to the designed ratio to obtain a mixed aggregate.

[0089] Step 2: Heat the matrix asphalt to 128 °C, and sequentially add the mixed aggregate, microcrystalline cellulose, waste rubber powder, and palmitic acid-lauric acid / vermiculite phase change material, and mix evenly to obtain the high-temperature warm-mix rubber asphalt mixture.

[0090] Among them, the preparation method of the coarse aggregate includes the following content:

[0091] Step a: Blend 1 kg of ethylene propylene diene monomer rubber, 1.5 kg of carboxyl nitrile rubber, and an organic auxiliary agent at 80 °C for 50 min to obtain a blend compound.

[0092] Step b: Add 75 g of sulfur and 3.5 kg of toluene to the blend compound, mix evenly to obtain a mixed glue slurry.

[0093] Step c, immersing optical fiber waste particles with a particle size of 3 mm into the mixed slurry, sieving, and drying to obtain impregnated particles;

[0094] Step d: Repeat step c three times to obtain coarse aggregate.

[0095] The organic auxiliary agent includes the following components in percentage by mass: 35% of accelerator TMTD, 25% of antioxidant and 40% of antioxidant 4020.

[0096] The fine aggregate includes the following components in percentage by mass: 80% of quartz sand, 5% of ceramic powder and 15% of slag powder.

[0097] The particle size of the waste rubber powder is 0.8 mm.

[0098] Comparative Example 1

[0099] This comparative example provides a high-temperature resistant warm-mix rubber asphalt mixture, which differs from Example 4 in that the phase change material used is a lauric acid / vermiculite composite material, specifically including the following contents:

[0100] S1, 500g of dried vermiculite was heated to 300°C at a heating rate of 5°C / min, kept warm for 30min, then heated to 500°C at a heating rate of 4°C / min for a second time, kept warm for 1h, and then cooled to room temperature at a cooling rate of 20°C / min to obtain 471g of vermiculite matrix;

[0101] S2. Under an inert atmosphere, 240 g of lauric acid was mixed with the vermiculite matrix, and the mixture was immersed at 80° C. for 2 h, filtered, and dried at 80° C. for 4 h to obtain the lauric acid / vermiculite phase change material.

[0102] The high-temperature resistant warm-mix rubber asphalt mixture comprises the following raw material components in parts by mass: 20 parts of coarse aggregate, 13 parts of fine aggregate, 4 parts of lauric acid / vermiculite phase change material, 8 parts of polyethylene wax, 17 parts of waste rubber powder and 68 parts of matrix asphalt.

[0103] The preparation method of the high temperature resistant warm mix rubber asphalt mixture comprises the following steps:

[0104] Step 1: Weigh coarse aggregate and fine aggregate according to the designed proportion to obtain mixed aggregate;

[0105] Step 2: Heat the base asphalt to 140° C., add the mixed aggregate, polyethylene wax, waste rubber powder and lauric acid / vermiculite phase change material in sequence, mix them evenly, and obtain the high-temperature resistant warm-mix rubber asphalt mixture.

[0106] The method for preparing the coarse aggregate comprises the following steps:

[0107] Step a, blending 1 kg of EPDM rubber, 1.5 kg of carboxylated nitrile rubber and an organic additive at 80° C. for 50 minutes to obtain a blended rubber material;

[0108] Step b, adding 75g of sulfur and 3.5kg of toluene to the blended rubber material, mixing well to obtain a mixed rubber slurry;

[0109] Step c, immersing optical fiber waste particles with a particle size of 3 mm into the mixed slurry, sieving, and drying to obtain impregnated particles;

[0110] Step d: Repeat step c three times to obtain coarse aggregate.

[0111] The organic auxiliary agent includes the following components in percentage by mass: 32% of accelerator TMTD, 30% of antioxidant and 38% of antioxidant 4020.

[0112] The fine aggregate includes the following components in percentage by mass: 75% of quartz sand, 8% of ceramic powder and 17% of slag powder.

[0113] The particle size of the waste rubber powder is 0.6 mm.

[0114] Comparative Example 2

[0115] This comparative example provides a high-temperature resistant warm-mix rubber asphalt mixture, which differs from Example 4 in that the phase change material used is a palmitic acid / vermiculite composite material, specifically comprising the following contents:

[0116] S1, 500g of dried vermiculite was heated to 300°C at a heating rate of 5°C / min, kept warm for 30min, then heated to 500°C at a heating rate of 4°C / min for a second time, kept warm for 1h, and then cooled to room temperature at a cooling rate of 20°C / min to obtain 471g of vermiculite matrix;

[0117] S2. Under an inert atmosphere, 240 g of palmitic acid was mixed with the vermiculite matrix, and the mixture was immersed at 80° C. for 2 h, filtered, and dried at 80° C. for 4 h to obtain the palmitic acid / vermiculite phase change material.

[0118] The high-temperature resistant warm-mix rubber asphalt mixture comprises the following raw material components in parts by mass: 20 parts of coarse aggregate, 13 parts of fine aggregate, 4 parts of palmitic acid / vermiculite composite material, 8 parts of polyethylene wax, 17 parts of waste rubber powder and 68 parts of matrix asphalt.

[0119] The preparation method of the high temperature resistant warm mix rubber asphalt mixture comprises the following steps:

[0120] Step 1: Weigh coarse aggregate and fine aggregate according to the designed proportion to obtain mixed aggregate;

[0121] Step 2: Heat the base asphalt to 140°C, and successively add the mixed aggregate, polyethylene wax, waste rubber powder, and palmitic acid - lauric acid / vermiculite phase change material, and mix evenly to obtain the high - temperature warm - mix rubber asphalt mixture.

[0122] Among them, the preparation method of the coarse aggregate includes the following content:

[0123] Step a: Blend 1 kg of ethylene propylene diene monomer rubber, 1.5 kg of carboxyl nitrile rubber, and organic additives at 80°C for 50 min to obtain a blended rubber compound;

[0124] Step b: Add 75 g of sulfur and 3.5 kg of toluene to the blended rubber compound, and mix evenly to obtain a mixed rubber slurry;

[0125] Step c: Immerse the optical fiber waste particles with a particle size of 3 mm into the mixed rubber slurry, screen, and dry to obtain impregnated particles;

[0126] Step d: Repeat the operation of step c 3 times to obtain the coarse aggregate.

[0127] Among them, the organic additives include components with the following mass percentages: 32% of accelerator TMTD, 30% of antioxidant, and 38% of antiozonant 4020.

[0128] The fine aggregate includes components with the following mass percentages: 75% of quartz sand, 8% of ceramic powder, and 17% of slag micro - powder.

[0129] The particle size of the waste rubber powder is 0.6 mm.

[0130] Comparative Example 3

[0131] This comparative example provides a high - temperature warm - mix rubber asphalt mixture, which is different from Example 4 in that: no phase change material is added, and it specifically includes the following content:

[0132] The high - temperature warm - mix rubber asphalt mixture includes the following raw material components in parts by mass: 20 parts of coarse aggregate, 13 parts of fine aggregate, 8 parts of polyethylene wax, 17 parts of waste rubber powder, and 68 parts of base asphalt.

[0133] The preparation method of the high - temperature warm - mix rubber asphalt mixture includes the following steps:

[0134] Step 1: Weigh the coarse aggregate and fine aggregate according to the designed ratio to obtain the mixed aggregate;

[0135] Step 2: Heat the base asphalt to 140°C, and successively add the mixed aggregate, polyethylene wax, and waste rubber powder, and mix evenly to obtain the high - temperature warm - mix rubber asphalt mixture.

[0136] Among them, the preparation method of the coarse aggregate includes the following content:

[0137] Step a: Blend 1 kg of ethylene propylene diene monomer rubber, 1.5 kg of carboxylated nitrile butadiene rubber and an organic auxiliary agent at 80 °C for 50 min to obtain a blended rubber compound.

[0138] Step b: Add 75 g of sulfur and 3.5 kg of toluene to the blended rubber compound, mix well to obtain a mixed rubber slurry.

[0139] Step c: Immerse optical fiber waste particles with a particle size of 3 mm into the mixed rubber slurry, sieve, and dry to obtain impregnated particles.

[0140] Step d: Repeat the operation of Step c three times to obtain coarse aggregate.

[0141] Among them, the organic auxiliary agent includes components with the following mass percentages: 32% of accelerator TMTD, 30% of antioxidant, and 38% of antioxidant 4020.

[0142] The fine aggregate includes components with the following mass percentages: 75% of quartz sand, 8% of ceramic powder, and 17% of slag micro powder.

[0143] The particle size of the waste rubber powder is 0.6 mm.

[0144] To further reflect the technical effects of the present invention, the present invention conducted the following tests on the temperature adjustment performance of the asphalt mixtures obtained in Examples 4 - 6 and Comparative Examples 1 - 3: Starting from 25 °C, the asphalt mixtures were heated together with the environmental chamber, and their heating processes were recorded. The results are shown in Table 1.

[0145] Table 1 Record of the heating process

[0146]

[0147] The present invention also conducted the following performance tests on the asphalt mixtures prepared in Examples 4 - 6 and Comparative Examples 1 - 3 according to the "Test Procedures for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20 - 2011):

[0148] The rutting test (dynamic stability) and four - point bending fatigue life test of the asphalt mixtures obtained in Examples 4 - 6 and Comparative Examples 1 - 3 under normal temperature and high - temperature environments (65 °C) were carried out, and the test results are shown in Table 2.

[0149] Table 2 Test results

[0150]

[0151]

[0152] It can be seen from Table 1 and Table 2 that the high-temperature resistant warm-mix rubber asphalt mixture provided by the present invention has excellent cooling performance and can maintain a relatively stable temperature range even at high temperatures. Although the dynamic stability and fatigue life at high temperatures are weakened, they can still maintain relatively good performance.

[0153] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-temperature resistant warm mix rubber asphalt mixture, characterized in that: It includes the following raw material components in parts by mass: 15 - 25 parts of coarse aggregate, 10 - 15 parts of fine aggregate, 3 - 6 parts of palmitic acid - lauric acid / vermiculite phase change material, 5 - 10 parts of warm mix additive, 15 - 20 parts of waste rubber powder, and 65 - 70 parts of matrix asphalt; The coarse aggregate has a core - shell structure, wherein the core layer material is optical fiber waste particles, and the shell layer material is ethylene propylene diene monomer - carboxy nitrile butadiene rubber polymer.

2. The high-temperature resistant warm mix rubber asphalt mixture according to claim 1, characterized in that: The preparation method of the palmitic acid - lauric acid / vermiculite phase change material includes the following steps: S1. Heat the dried vermiculite to 250℃ - 300℃ for the first time, keep it warm for the first time, then heat it to 450℃ - 500℃ for the second time, keep it warm for the second time, and then cool it down to obtain a vermiculite matrix; S2. Under an inert atmosphere, mix palmitic acid, lauric acid with the vermiculite matrix, keep it warm at 75℃ - 90℃ for 1h - 2h, filter, and dry to obtain the palmitic acid - lauric acid / vermiculite phase change material.

3. The high-temperature resistant warm mix rubber asphalt mixture according to claim 2, characterized in that: In S1, both the first heating and the second heating adopt a programmed heating method, wherein the heating rate of the first heating is 5℃ / min - 10℃ / min, and the heating rate of the second heating is 4℃ / min - 6℃ / min; and / or In S1, the cooling adopts a programmed cooling method, and the cooling rate is 10℃ / min - 20℃ / min.

4. The high-temperature resistant warm mix rubber asphalt mixture according to claim 2, characterized in that: In S1, the time for the first heat preservation is 30min - 60min; and / or In S1, the time for the second heat preservation is 1h - 2h; and / or In S2, the mass ratio of palmitic acid, lauric acid to the vermiculite matrix is 0.5:0.5:1 - 0.8:1.5:

2.

5. The high-temperature resistant warm mix rubber asphalt mixture according to claim 1, characterized in that: The preparation method of the coarse aggregate includes the following steps: Step a. Blend ethylene propylene diene monomer, carboxy nitrile butadiene rubber and organic additives at 70℃ - 80℃ to obtain a blended rubber compound; Step b. Add a vulcanizing agent and an organic solvent to the blended rubber compound, mix evenly to obtain a mixed rubber slurry; Step c. Immerse the crushed optical fiber waste particles into the mixed rubber slurry, screen, and dry to obtain impregnated particles; Step d. Repeat the operation of step c for 2 - 4 times to obtain the coarse aggregate.

6. The high-temperature resistant warm mix rubber asphalt mixture according to claim 5, characterized in that: The mass ratio of ethylene propylene diene monomer to carboxy nitrile butadiene rubber is 1 - 1:1 - 2; and / or The mass ratio of the organic additive to the total mass of ethylene propylene diene monomer and carboxy nitrile butadiene rubber is 0.03:1 - 0.05:1; and / or The organic additive includes components with the following mass percentages: 30% - 35% of accelerator, 25% - 30% of antioxidant, and the balance of anti - aging agent; and / or The vulcanizing agent is sulfur; and / or The organic solvent is toluene; and / or The mass ratio of the blended rubber compound, vulcanizing agent and organic solvent is 80:2:120 - 100:4:

150.

7. The high-temperature resistant warm mix rubber asphalt mixture according to claim 5, characterized in that: In step a, the blending time is 30min - 50min; and / or The particle size of the optical fiber waste particles is 3cm - 5cm.

8. The high-temperature resistant warm mix rubber asphalt mixture according to claim 1, characterized in that: The fine aggregate includes components with the following mass percentages: 70% - 85% of quartz sand, 5% - 10% of ceramic powder, and the balance of slag micro - powder; and / or The warm mix additive is any one of microcrystalline cellulose or polyethylene wax; and / or The particle size of the waste rubber powder is 0.5 mm - 1 mm.

9. A preparation method of a high-temperature resistant warm mix rubber asphalt mixture according to any one of claims 1-8, characterized in that: It includes the following steps: Step 1: Weigh the coarse aggregate and fine aggregate according to the designed ratio, and mix them evenly to obtain the mixed aggregate; Step 2: Heat the matrix asphalt to 120°C - 150°C, and sequentially add the mixed aggregate, warm mix agent, waste rubber powder, and palmitic acid - lauric acid / vermiculite phase change material, and mix them evenly to obtain the high-temperature resistant warm mix rubber asphalt mixture.

10. Application of the high-temperature resistant warm mix rubber asphalt mixture according to any one of claims 1 - 8 in the field of road engineering construction.

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