A porous aggregate for road surface cooling, a modified asphalt mixture, and a preparation method thereof.

Abstract

This invention provides a porous aggregate for road surface cooling, a modified asphalt mixture, and a preparation method thereof, made from the following raw materials: mineral aggregate, road asphalt, porous aggregate for road surface cooling, surface treatment agent I, and surface treatment agent II. The porous aggregate for road surface cooling is made from the following raw materials: bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate, and hydroxypropyl methylcellulose. Compared to the single-level cooling of existing asphalt pavement "active cooling" technologies, the modified asphalt concrete of this invention has a triple cooling effect, including thermoelectric effect, heat insulation function, and reflection of sunlight, significantly improving the cooling efficiency of asphalt pavement during the high-temperature period in summer.

Description

Technical Field

[0001] This invention belongs to the field of road materials technology, and relates to modified asphalt, specifically to a porous aggregate for road surface cooling, a modified asphalt mixture, and a preparation method thereof. Background Technology

[0002] Asphalt pavement is widely used in my country's road construction due to its advantages such as smooth surface and comfortable driving. However, traditional asphalt pavement has a strong heat absorption and storage capacity, which leads to the pavement temperature reaching 63-68℃ during the high-temperature period in summer, resulting in the aggravation of rutting disease and urban heat island effect.

[0003] Scholars have conducted research on "active cooling" technology for asphalt pavements, with existing findings categorized into three types based on cooling principles: reflection, radiation, and insulation. Insulation technology achieves pavement layer insulation by replacing or partially replacing coarse aggregates with thermally resistive materials; however, the problem of road performance degradation due to the poor performance of thermally resistive aggregates remains unresolved. Reflective coatings, due to material and environmental limitations, often suffer from inherent drawbacks such as high cost, poor durability, low reusability, complex construction processes, environmental pollution, and negative impacts on pavement performance. Radiation technology uses infrared radiation powders to radiate pavement heat energy into outer space for cooling, but the cooling effect is poor, the radiation wavelength is difficult to control, and the reflection of thermal radiation by the atmosphere can even exacerbate the urban heat island effect. In summary, current research has not yet achieved a harmonious balance between pavement cooling function, road performance, and the urban environment. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a porous aggregate for road surface cooling, thereby solving the technical problem that the cooling effect of modified asphalt mixtures in the existing technology needs to be improved.

[0005] Another objective of this invention is to provide a modified asphalt mixture for road surface cooling and its preparation method, thereby solving the technical problem in the prior art that it is difficult to simultaneously achieve the road surface cooling function, road performance, and urban environment considerations of modified asphalt.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A porous aggregate for road surface cooling is made from the following raw materials: bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate and hydroxypropyl methylcellulose.

[0008] Specifically, the mass ratio of bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate and hydroxypropyl methylcellulose is 2:0.2:5:2:0.1.

[0009] Specifically, the porous aggregate used for road surface cooling is in block form with a particle size between 2 and 3 mm.

[0010] This invention also protects a method for preparing porous aggregate for road surface cooling as described above, the method comprising the following steps:

[0011] Step 1, Pretreatment of Bornite Powder:

[0012] Step 101: Place the bornite powder in a magnetically stirred water bath containing deionized water, add N,N-dimethyloctadecylamine oxide, stir for 2 hours at a stirring temperature of 60°C and a stirring speed of 1000 rpm.

[0013] Step 102: Place nano-titanium carbide in a deionized aqueous solution, add polyetheramine-grafted acrylic acid, ultrasonically disperse for 20 minutes, take the lower layer suspension, and store for later use.

[0014] Step 103: Place the bornite powder solution and the nano-titanium carbide solution in a planetary high-energy ball mill, mill at 200 rpm for 2 hours to obtain bornite powder / nano-titanium carbide solution.

[0015] Step 104: Take out the ball-milled bornite powder / nano titanium carbide solution and dry it in a 160℃ oven until constant weight. Take out the dried solid product, grind it and sieve it to obtain nano-modified bornite powder.

[0016] Step 2, Preparation of porous aggregate for road surface cooling:

[0017] Step 201: Pour the bornite powder obtained in Step 1 into a starch solution, add 1,4-butanediol diacrylate, stir evenly, and use a microwave heating method with a microwave power of 800W and a heating time of 20min to obtain a porous aggregate precursor coated with bornite powder.

[0018] Step 202: Immerse the porous aggregate precursor in an aqueous solution of hydroxypropyl methylcellulose, maintain the temperature at 90°C, filter out the porous aggregate precursor, and pyrolyze and carbonize it at a high temperature of 350°C to obtain porous aggregate coated with bornite powder.

[0019] Step 203: The porous aggregate coated with bornite powder is crushed and put into an extrusion granulator. The wet granulation method is used to granulate the aggregate, and the particle size is set to 2-3 mm to obtain porous aggregate with relatively uniform size.

[0020] Step 204: Take out the granulated porous aggregate and dry it in a 60℃ oven until constant weight. Take out the dried solid product, and after sieving and dispersing, obtain the modified asphalt mixture for road cooling.

[0021] This invention also protects a modified asphalt mixture for road cooling, made from the following raw materials: mineral aggregate, road asphalt, porous aggregate for road cooling, surface treatment agent I, and surface treatment agent II.

[0022] The porous aggregate for road surface cooling is the same as described above.

[0023] Specifically, by weight, it is made from the following raw materials: 86-94 parts of mineral aggregate, 6-12 parts of porous aggregate for road cooling, 3-7 parts of road asphalt, 1-2 parts of surface treatment agent I, and 0-0.5 parts of surface treatment agent II, wherein the sum of the weight parts of mineral aggregate and porous aggregate for road cooling is 100 parts.

[0024] Preferably, the material is made from the following raw materials in parts by weight: 88 parts mineral aggregate, 12 parts porous aggregate for road cooling, 4.4 parts road asphalt, 1 to 2 parts surface treatment agent I, and 0.4 parts surface treatment agent II.

[0025] The surface treatment agent I is N,N-dimethyloctadecylamine oxide, sodium N-dodecyliminodiacetate, or disodium lauroylamphoteric diacetate.

[0026] The surface treatment agent II is polyetheramine grafted acrylic acid or sodium dodecylbenzenesulfonate.

[0027] The present invention also protects a method for preparing a modified asphalt mixture for road cooling as described above. The method includes the following steps: first, replacing the 2.36mm fine aggregate with porous aggregate for road cooling by an equal volume; then heating the road asphalt to 150±5℃ and heating the aggregate to 180±5℃; then adding the asphalt to the aggregate and mixing for 90s; finally adding mineral powder and continuing to mix for 90s to 100s to obtain a modified asphalt mixture for asphalt road cooling.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] (I) Compared with the single cooling of existing asphalt pavement “active cooling” technology, the modified asphalt concrete of the present invention has a triple cooling effect, including thermoelectric effect, heat insulation function and reflection of sunlight, which significantly improves the cooling effect of asphalt pavement during the high temperature period in summer.

[0030] (II) Bornite powder has a significant thermoelectric effect, with its Seebeck coefficient being much higher than that of traditional thermoelectric materials such as tourmaline. Moreover, the thermoelectric coefficient gradually increases with increasing temperature. The resulting modified asphalt concrete can convert road surface heat energy during the high-temperature period in summer and improve the road surface cooling effect.

[0031] (III) This invention combines energy conversion and porous property theory, and uses bornite powder and organic matter as basic materials to prepare porous materials coated with bornite powder, namely porous aggregates for road cooling. Compared with traditional mineral materials, the porous aggregates prepared by this invention have significant thermoelectric effects and heat insulation functions.

[0032] (IV) This invention uses nano-titanium carbide to modify the surface of bornite powder, which improves the thermoelectric effect of bornite powder, ensures the material stability of bornite powder under typical working conditions, and makes it easier to disperse the charge generated by the thermoelectric effect in asphalt, thereby improving the service performance of asphalt pavement.

[0033] (V) To address the problem of road performance degradation caused by replacing coarse aggregate with traditional heat-insulating aggregate, this invention prepares porous aggregate with a particle size of 2-3 mm for road cooling, and prepares modified asphalt mixture for asphalt pavement cooling by replacing 2.36 mm fine aggregate with equal volume. Under the premise of achieving the technical goal of asphalt pavement cooling, the long-term stability of asphalt pavement road performance is guaranteed.

[0034] (VI) The bornite powder in this invention has a certain reflectivity for light of all wavelengths. The reflection effect has two benefits for asphalt pavement: ① It reflects sunlight, which helps to cool down the asphalt pavement in summer; ② It reflects ultraviolet and infrared rays, which can achieve the effect of resisting ultraviolet aging and thermo-oxidative aging, thus extending the service life of asphalt pavement.

[0035] (VII) Bornite has huge domestic reserves and low cost. It is generally used for smelting copper and iron metals. Based on the excellent properties of bornite powder such as thermoelectric effect, low thermal conductivity and reflection effect, this invention develops new uses of bornite as heat insulation material and thermoelectric material. Attached Figure Description

[0036] Figure 1 This is a diagram showing the thermal conductivity of traditional thermal resistance materials.

[0037] Figure 2 This is a Seebeck coefficient diagram for traditional thermoelectric materials.

[0038] Figure 3 This is a comparison chart of the cooling performance of modified asphalt concrete in Examples 1 to 5 and Comparative Example 1.

[0039] Figure 4 This is a comparison chart of the cooling performance of modified asphalt concrete in Example 4 and Comparative Examples 1 to 4.

[0040] Figure 5(a) shows the test results of high temperature rutting resistance and low temperature crack resistance of Examples 1 to 5.

[0041] Figure 5(b) shows the water stability test results of Examples 1 to 5.

[0042] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the prior art.

[0044] In this invention, the road asphalt can be selected from 70# base asphalt, 90# base asphalt, SBS modified asphalt, or rubber powder modified asphalt. Surface treatment agent I can be selected from N,N-dimethyloctadecylamine oxide, sodium N-dodecyliminodiacetate, or disodium lauroamphodiacetate. Surface treatment agent II can be selected from polyetheramine-grafted acrylic acid or sodium dodecylbenzenesulfonate. The number average molecular weight of the polyetheramine-grafted acrylic acid is 600-1200.

[0045] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0046] Example 1:

[0047] This embodiment provides a modified asphalt mixture for road surface cooling, which is made from the following raw materials by weight: 94 parts of mineral aggregate, 6 parts of porous aggregate for road surface cooling, 4 parts of road asphalt, 1 part of surface treatment agent I, and 0.1 parts of surface treatment agent II.

[0048] The aggregate gradation is AC-13.

[0049] The porous aggregate for road surface cooling is made from the following raw materials: bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate, and hydroxypropyl methylcellulose. The mass ratio of bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate, and hydroxypropyl methylcellulose is 2:0.2:5:2:0.1. The porous aggregate for road surface cooling is in block form with a particle size between 2 and 3 mm.

[0050] The road asphalt is 70# base asphalt.

[0051] Surface treatment agent I is N,N-dimethyloctadecylamine oxide.

[0052] Surface treatment agent II is polyetheramine grafted with acrylic acid.

[0053] The preparation method of the modified asphalt mixture for road surface cooling in this embodiment includes the following steps:

[0054] Step 1, Pretreatment of Bornite Powder:

[0055] Step 101: Place the bornite powder in a magnetically stirred water bath containing deionized water, add N,N-dimethyloctadecylamine oxide, stir for 2 hours at a stirring temperature of 60°C and a stirring speed of 1000 rpm.

[0056] Step 102: Place nano-titanium carbide in a deionized aqueous solution, add polyetheramine-grafted acrylic acid, ultrasonically disperse for 20 minutes, take the lower layer suspension, and store for later use.

[0057] Step 103: Place the bornite powder solution and the nano-titanium carbide solution in a planetary high-energy ball mill, mill at 200 rpm for 2 hours to obtain bornite powder / nano-titanium carbide solution.

[0058] Step 104: Take out the ball-milled bornite powder / nano titanium carbide solution and dry it in a 160℃ oven until constant weight. Take out the dried solid product, grind it and sieve it to obtain nano-modified bornite powder.

[0059] Step 2, Preparation of porous aggregate for road surface cooling:

[0060] Step 201: Pour the bornite powder obtained in Step 1 into a starch solution, add 1,4-butanediol diacrylate, stir evenly, and use a microwave heating method with a microwave power of 800W and a heating time of 20min to obtain a porous aggregate precursor coated with bornite powder.

[0061] Step 202: Immerse the porous aggregate precursor in an aqueous solution of hydroxypropyl methylcellulose, maintain the temperature at 90°C, filter out the porous aggregate precursor, and pyrolyze and carbonize it at a high temperature of 350°C to obtain porous aggregate coated with bornite powder.

[0062] Step 203: The porous aggregate coated with bornite powder is crushed and put into an extrusion granulator. The wet granulation method is used to granulate the aggregate, and the particle size is set to 2-3 mm to obtain porous aggregate with relatively uniform size.

[0063] Step 204: Take out the granulated porous aggregate and dry it in a 60℃ oven until constant weight. Take out the dried solid product, and after sieving and dispersing, obtain the modified asphalt mixture for road cooling.

[0064] Step 3: Preparation of modified asphalt mixture for road surface cooling:

[0065] First, replace the 2.36mm fine aggregate with porous aggregate of equal volume to cool the road surface; then heat the road asphalt to 150±5℃ and the aggregate to 180±5℃. Then add the asphalt to the aggregate and mix for 90s. Finally, add the mineral powder and continue mixing for 90s to 100s to obtain the modified asphalt mixture for cooling asphalt pavement.

[0066] Example 2:

[0067] This embodiment provides a modified asphalt mixture for road surface cooling, which is made from the following raw materials by weight: 92 parts of mineral aggregate, 8 parts of porous aggregate for road surface cooling, 4.2 parts of road asphalt, 1 part of surface treatment agent I, and 0.2 parts of surface treatment agent II.

[0068] The selection and specifications of raw materials in this embodiment are the same as those in Embodiment 1.

[0069] The preparation method of the modified asphalt mixture for road surface cooling in this embodiment is the same as that in Example 1.

[0070] Example 3:

[0071] This embodiment provides a modified asphalt mixture for road surface cooling, which is made from the following raw materials by weight: 90 parts of mineral aggregate, 10 parts of porous aggregate for road surface cooling, 4.4 parts of road asphalt, 1 part of surface treatment agent I, and 0.3 parts of surface treatment agent II.

[0072] The selection and specifications of raw materials in this embodiment are the same as those in Embodiment 1.

[0073] The preparation method of the modified asphalt mixture for road surface cooling in this embodiment is the same as that in Example 1.

[0074] Example 4:

[0075] This embodiment provides a modified asphalt mixture for road surface cooling, which is made from the following raw materials by weight: 88 parts of mineral aggregate, 12 parts of porous aggregate for road surface cooling, 4.4 parts of road asphalt, 2 parts of surface treatment agent I, and 0.4 parts of surface treatment agent II.

[0076] The selection and specifications of raw materials in this embodiment are the same as those in Embodiment 1.

[0077] The preparation method of the modified asphalt mixture for road surface cooling in this embodiment is the same as that in Example 1.

[0078] Example 5:

[0079] This embodiment provides a modified asphalt mixture for road surface cooling, which is made from the following raw materials by weight: 86 parts of mineral aggregate, 14 parts of porous aggregate for road surface cooling, 4.5 parts of road asphalt, 2 parts of surface treatment agent I, and 0.5 parts of surface treatment agent II.

[0080] The selection and specifications of raw materials in this embodiment are the same as those in Embodiment 1.

[0081] The preparation method of the modified asphalt mixture for road surface cooling in this embodiment is the same as that in Example 1.

[0082] Comparative Example 1:

[0083] This comparative example provides a common asphalt concrete with the same gradation type as Example 1, made from the following raw materials in parts by weight: 100 parts mineral aggregate and 4.4 parts road asphalt.

[0084] The preparation method of this comparative asphalt concrete is as follows: heat the asphalt to 150°C, heat the aggregate in the mineral aggregate to 180°C, then add the heated asphalt to the aggregate and mix for 90 seconds, finally add the mineral powder in the mineral aggregate and continue mixing for 90 seconds to obtain asphalt concrete.

[0085] Comparative Example 2:

[0086] This comparative example provides a modified asphalt mixture for road surface cooling. The difference from Example 4 is that the bornite powder is directly used to prepare porous aggregate without nano-modification.

[0087] Comparative Example 3:

[0088] This comparative example presents a modified asphalt mixture for road surface cooling, made from the following raw materials in parts by weight: 88 parts mineral aggregate, 12 parts bornite, 4.4 parts road asphalt, 2 parts surface treatment agent I, and 0.4 parts surface treatment agent II.

[0089] The preparation method of the modified asphalt mixture used for road surface cooling in this comparative example is as follows:

[0090] Bornite is crushed and fed into an extrusion granulator for wet granulation. The particle size is set to 2-3 mm to obtain aggregate with relatively uniform size. Bornite aggregate is used to replace 2.36 mm fine aggregate by volume. The road asphalt is heated to 150°C and the aggregate is heated to 180°C. Then the asphalt is added to the aggregate and mixed for 90 seconds. Finally, mineral powder is added and mixed for another 90 seconds to obtain a modified asphalt mixture for road cooling.

[0091] Comparative Example 4:

[0092] This comparative example presents a modified asphalt mixture for road surface cooling, made from the following raw materials in parts by weight: 88 parts mineral aggregate, 12 parts porous aggregate for road surface cooling, and 4.4 parts road asphalt.

[0093] The preparation method of the modified asphalt mixture for road surface cooling in this comparative example is basically the same as that in Example 4, except that surface treatment agent I and surface treatment agent II are not added during the preparation of the porous aggregate for cooling.

[0094] Performance testing:

[0095] The performance test of modified asphalt mixtures used for road cooling includes three parts: basic aggregate properties, cooling performance of modified asphalt concrete, and road performance test of modified asphalt concrete.

[0096] I. Basic properties of aggregates:

[0097] (1) Thermal resistance characteristics:

[0098] Depend on Figure 1 It is known that the thermal conductivity of traditional thermal resistance materials such as sepiolite and palygorskite ranges from 0.282 to 1.072 W / (m·K). Compared with traditional thermal resistance materials, the thermal conductivity of bornite powder is significantly reduced, with a decrease of 52.5% to 87.5%, indicating that bornite has great potential as a thermal resistance material. Among thermal resistance materials, the porous aggregate for road cooling in this invention has the lowest thermal conductivity, indicating that the effective combination of porous properties and thermal insulation materials will further reduce the thermal conductivity of thermal resistance aggregates.

[0099] Depend on Figure 2 It is known that tourmaline, hemimorphite, and other materials are traditional thermoelectric materials with Seebeck coefficients of 147–172 μV·K. -1 Bornite A is a natural bornite, and its Seebeck coefficient is significantly higher than that of traditional thermoelectric materials, reaching 300 μV·K at room temperature. -1 The increase reached 42.7% to 48%, indicating that the thermoelectric properties of bornite are superior to those of traditional thermoelectric materials, and it can be developed into a new type of thermoelectric material. Bornite B is a nano-modified bornite powder, and its Seebeck coefficient is further improved compared with natural bornite. This is because the nano-modification process enriches the surface particles and nanostructure of the bornite powder, resulting in a higher carrier mobility, thereby improving the thermoelectric effect. The Seebeck coefficient of the porous aggregate for cooling in this invention is between that of bornite A and bornite B, indicating that the composite of bornite powder and porous materials still maintains a stable thermoelectric effect.

[0100] II. Cooling performance of modified asphalt concrete:

[0101] Depend on Figure 3It can be seen that when the atmospheric temperature is 36.7℃, the average temperature of the rutting slab made from ordinary road asphalt concrete in Comparative Example 6 exceeds 60℃, which easily causes high-temperature rutting disease on asphalt pavements in summer. In Examples 1-5, the average temperature of the modified asphalt mixture rutting slabs used for cooling asphalt pavements is 52.4-54.9℃, showing excellent cooling effect in summer. Compared with ordinary road asphalt, its cooling effect reaches 7.2-9.8℃. Comparing Examples 1-5, the cooling effect of the modified asphalt mixture used for cooling asphalt pavements shows a trend of first increasing and then decreasing with the increase of the amount of porous aggregate used for cooling. Among them, when the amount of porous aggregate is 12 parts, i.e., Example 4, the modified asphalt concrete with the best cooling effect is obtained, with a cooling effect of 9.8℃. Therefore, Example 4 is the preferred example for summer cooling effect.

[0102] analyze Figure 4 It can be seen that Comparative Example 1 is a common AC-13 type asphalt concrete rutting slab, Comparative Example 2 is a rutting slab finally obtained by using bornite powder without nano-modification, and Comparative Example 3 is a rutting slab obtained by directly replacing 2.36mm aggregate with bornite. The only difference between Comparative Example 4 and Example 4 is that surface treatment agents I and II are not added. Compared with Comparative Example 1, the average temperature of the rutting slabs of Comparative Examples 2 to 4 is reduced. The order of cooling effect from best to worst is Comparative Example 4 → Comparative Example 2 → Comparative Example 3, indicating that the surface treatment agent has a greater impact on the cooling effect than nano-modification. In the high-temperature rutting test, Example 4 showed a temperature reduction of 9.8℃, which was significantly better than the comparative examples. The cooling effect was 26% to 100% higher than that of Comparative Examples 2 to 4. This indicates that the modified asphalt concrete prepared by the present invention, using bornite powder as a porous aggregate substrate for cooling, combined with the principles of energy conversion and porous properties, has a significant cooling effect. It breaks through the bottleneck of the existing "active cooling technology" for asphalt pavement and is of great significance for preventing the formation of road surface diseases such as high-temperature rutting, alleviating the urban "heat island effect", and extending the service life of roads.

[0103] III. Road performance of modified asphalt concrete:

[0104] In accordance with the relevant provisions of the "Test Procedures for Asphalt and Asphalt Concrete in Highway Engineering" (JTG E20-2011), the high-temperature rutting resistance, low-temperature crack resistance and water stability of the modified asphalt concrete in Examples 1 to 5 of this invention were determined. The test results are shown in Figure 5(a) and Figure 5(b).

[0105] As shown in Figures 5(a) and 5(b), the dynamic stability, failure strain, residual stability, and freeze-thaw splitting residual strength ratio of the modified asphalt concrete of this invention all meet the relevant technical requirements of the "Test Procedures for Asphalt and Asphalt Concrete in Highway Engineering" (JTG E20-2011). Furthermore, compared with Examples 1-5, Example 4 of this invention exhibits the best performance in all aspects.

Claims

1. A modified asphalt mixture for road surface cooling, characterized in that, Made from the following raw materials: mineral aggregate, road asphalt, porous aggregate for road cooling, surface treatment agent I and surface treatment agent II; The surface treatment agent I is N,N-dimethyloctadecylamine oxide; the surface treatment agent II is polyetheramine grafted with acrylic acid; The porous aggregate for road surface cooling is made from the following raw materials: bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate and hydroxypropyl methylcellulose; The porous aggregate for road surface cooling is prepared by the following steps: Step 1, Pretreatment of Bornite Powder: Step 101: Place the bornite powder in a magnetically stirred water bath containing deionized water, add N,N-dimethyloctadecylamine oxide, stir for 2 h, the stirring temperature is 60℃, and the stirring speed is 1000 rpm. Step 102: Place nano-titanium carbide in a deionized aqueous solution, add polyetheramine-grafted acrylic acid, ultrasonically disperse for 20 min, take the lower layer suspension, and store for later use. Step 103: Place the bornite powder solution and the nano titanium carbide solution in a planetary high-energy ball mill, with a ball milling speed of 200 rpm and a ball milling time of 2 h to obtain bornite powder / nano titanium carbide solution. Step 104: Take out the ball-milled bornite powder / nano titanium carbide solution and dry it in a 160℃ oven until constant weight. Take out the dried solid product, grind it and sieve it to obtain nano-modified bornite powder. Step 2, Preparation of porous aggregate for road surface cooling: Step 201: Pour the bornite powder obtained in Step 1 into the starch solution, add 1,4-butanediol diacrylate, stir evenly, and use microwave heating method with microwave power of 800 W and heating time of 20 min to obtain a porous aggregate precursor coated with bornite powder. Step 202: Immerse the porous aggregate precursor in an aqueous solution of hydroxypropyl methylcellulose, maintain the temperature at 90°C, filter out the porous aggregate precursor, and pyrolyze and carbonize it at a high temperature of 350°C to obtain porous aggregate coated with bornite powder. Step 203: Crush the porous aggregate coated with bornite powder and put it into an extrusion granulator. Use wet granulation to granulate the aggregate, and set the particle size to 2-3 mm to obtain porous aggregate with uniform size. Step 204: Take out the granulated porous aggregate and dry it in a 60℃ oven until constant weight. Take out the dried solid product, sieve and disperse it to obtain porous aggregate for road cooling.

2. The modified asphalt mixture for road surface cooling as described in claim 1, characterized in that, The mass ratio of bornite powder, nano-titanium carbide, starch, 1,4-butanediol diacrylate and hydroxypropyl methylcellulose is 2:0.2:5:2:0.

1.

3. The modified asphalt mixture for road surface cooling as described in claim 1, characterized in that, The porous aggregate used for road surface cooling is in block form with a particle size between 2 and 3 mm.

4. The modified asphalt mixture for road surface cooling as described in claim 1, characterized in that, It is made from the following raw materials by weight: 86-94 parts of mineral aggregate, 6-12 parts of porous aggregate for road cooling, 3-7 parts of road asphalt, 1-2 parts of surface treatment agent I, and 0-0.5 parts of surface treatment agent II, wherein the sum of the weight parts of mineral aggregate and porous aggregate for road cooling is 100 parts.

5. The modified asphalt mixture for road surface cooling as described in claim 4, characterized in that, It is made from the following raw materials by weight: 88 parts mineral aggregate, 12 parts porous aggregate for road cooling, 4.4 parts road asphalt, 1 to 2 parts surface treatment agent I, and 0.4 parts surface treatment agent II.

6. A method for preparing a modified asphalt mixture for road surface cooling as described in any one of claims 1 to 5, characterized in that, The method includes the following steps: First, replace the 2.36 mm fine aggregate with porous aggregate of equal volume to cool the pavement; then heat the road asphalt to 150±5℃ and heat the aggregate to 180±5℃; then add the asphalt to the aggregate and mix for 90s; finally add the mineral powder and continue mixing for 90s to 100s to obtain the modified asphalt mixture for cooling asphalt pavement.

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