Crack self-healing asphalt mixture and preparation method thereof

Abstract

The invention relates to the technical field of asphalt mixtures, in particular to a crack self-healing asphalt mixture and a preparation method thereof. The crack self-healing asphalt mixture is prepared from the following raw materials in parts by mass: 10 to 20 parts of asphalt, 1 to 5 parts of carboxy nitrile rubber, 1 to 3 parts of copper fiber, 5 to 15 parts of carbon composite mineral fiber, 1 to 2 parts of dopamine, 10 to 20 parts of limestone powder, 5 to 15 parts of steel slag powder, 1 to 2 parts of dispersing agent, 40 to 80 parts of fine aggregate and 150 to 250 parts of coarse aggregate. According to the present invention, the characteristics of the component materials can be completely performed, the low temperature cracking of the asphalt pavement is reduced to the minimum, the self-healing can be performed to a certain extent, the cracking occurrence is effectively reduced, and the service life of the asphalt pavement is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt mixtures, and in particular to a crack self-healing asphalt mixture and a preparation method thereof. Background Art

[0002] Asphalt pavement has become a mainstream material for modern road construction due to its excellent driving comfort and repairability. However, cracks that develop over long periods of service severely limit its service life. Traditional asphalt mixtures rely on fiber reinforcement (such as polyester and lignin fibers) to slow crack propagation, but the fiber-asphalt interface is weak and lacks an active repair mechanism. Once cracks form, they continue to expand.

[0003] Existing asphalt becomes more brittle at low temperatures, and repeated freezing and thawing after moisture intrudes into cracks can easily cause structural damage, resulting in the freeze-thaw splitting strength of existing asphalt materials generally being lower than the specification requirements; conventional cutting and resurfacing processes have problems such as poor adhesion at the interface between new and old materials and high costs, forming a vicious cycle of repair and re-cracking.

[0004] Current improvements primarily enhance crack resistance by adding single fibers (such as carbon fibers or steel fibers). However, the physical bond between the fibers and asphalt prevents effective self-healing of cracks. Furthermore, the mismatch in expansion coefficients between the fibers and asphalt easily exacerbates thermal shrinkage cracks. Therefore, there is an urgent need to develop an asphalt mixture that combines crack resistance, self-healing properties, and low-temperature stability to fundamentally overcome the current technological bottleneck. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a crack self-healing asphalt mixture and a preparation method thereof.

[0006] A crack self-healing asphalt mixture, the raw materials of which include, by mass, 10-20 parts of asphalt, 1-5 parts of carboxyl nitrile rubber, 1-3 parts of copper fiber, 5-15 parts of carbon composite mineral fiber, 1-2 parts of dopamine, 10-20 parts of limestone powder, 5-15 parts of steel slag powder, 1-2 parts of dispersant, 40-80 parts of fine aggregate, and 150-250 parts of coarse aggregate.

[0007] Preferably, the asphalt is 70# base asphalt.

[0008] Preferably, the dispersant is zinc stearate.

[0009] Preferably, the aspect ratio of the copper fiber is 200-250.

[0010] Preferably, the fine aggregate is manufactured sand with a particle size of 1-3 mm.

[0011] Preferably, the coarse aggregate is limestone with a particle size of 3-25 mm; wherein the mass ratio of limestone with a particle size of 20-25 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm and limestone with a particle size of 3-5 mm is 5-10:5-10:1-4:1-2.

[0012] Preferably, the carbon composite mineral fiber is prepared by the following steps: soaking the mineral fiber in hydrochloric acid for 1-2 hours, washing with water, drying, calcining at 500-600°C for 1-2 hours under nitrogen protection, and cooling to room temperature; mixing the calcined product and asphalt, stirring evenly at 160-170°C, carbonizing at 900-1100°C for 5-10 hours under nitrogen protection, and cooling to room temperature.

[0013] More preferably, the concentration of hydrochloric acid is 1-1.5 mol / L.

[0014] More preferably, the mass ratio of the calcined product to the asphalt is 10-30:1-5.

[0015] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder and dispersant, dry and crush to obtain filler; S2. Add dopamine to a Tris-HCl solution with a pH of 8-9, add carbon composite mineral fiber thereto, stir in the dark for 5-10 hours, filter, wash, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and the fine aggregate separately, mix the dried coarse aggregate and the dried fine aggregate, add filler thereto in 2-3 times under stirring, stir evenly, adjust the temperature to 160-170° C., add load fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring and mix for 10-30 seconds to obtain a premix; S4. Heat the asphalt to 160-170°C, add the premix into the asphalt while stirring, and mix for 1-5 minutes.

[0016] Preferably, in S1, the drying is performed to a moisture content of ≤0.5%.

[0017] Beneficial effects: The present invention utilizes copper fibers to absorb crack expansion energy through plastic deformation, and cooperates with carbon composite mineral fibers loaded with dopamine to form a multi-level network structure at the crack. The polar groups on the surface of the loaded dopamine can cooperate with asphalt molecules to promote the migration of asphalt along the fiber surface to the crack area. At the same time, the capillary action of the fiber can accelerate the flow of asphalt and reduce the crack width.

[0018] The Ca in steel slag powder 2+It forms an ionic crosslinking network with the -COOH groups of carboxylated nitrile rubber, resulting in reversible fracture / recombination behavior under stress. As the crack expands, the crosslinks break, dissipating energy. Upon temperature rise, dynamic bond recombination enables the crack to repair itself. Combined with the synergistic effect of loaded dopamine, the crack self-healing performance is excellent.

[0019] The present invention utilizes copper fibers (aspect ratio > 200) and load fibers to form a multi-scale reinforcement system, wherein the copper fibers bridge macro cracks and the load fibers inhibit the expansion of micro cracks. The glass transition temperature of carboxyl nitrile rubber complements the low-temperature brittle point of asphalt, effectively reducing thermal shrinkage cracks, and achieving excellent freeze-thaw splitting strength. The combined effect has excellent anti-cracking effect and good road performance.

[0020] The present invention can give full play to the respective characteristics of the component materials, minimize the low-temperature cracking of the asphalt pavement, and can self-heal to a certain extent, effectively reducing the occurrence of cracking and extending the service life of the asphalt pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a comparison chart of the freeze-thaw splitting strength ratio and the maximum flexural tensile strain of the asphalt mixtures obtained in Example 5 and Comparative Examples 1-2.

[0022] Figure 2 The figure is a comparison of the rutting stability and scattering loss of the asphalt mixtures obtained in Example 5 and Comparative Examples 1-2.

[0023] Figure 3 The figure is a comparison chart of the strength recovery rate and crack healing rate of the asphalt mixtures obtained in Example 5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0024] The present invention will be further explained below with reference to specific embodiments.

[0025] The 70# matrix asphalt used below is sourced from Dongming Petrochemical. The carboxylated nitrile rubber used below is sourced from Japan's Zeon, with the brand name being 1072CGX. The copper fiber used below is purchased from Jiangxi Moubang New Materials Technology Co., Ltd., with a length of 8-10 mm and an aspect ratio of 240. The particle size of the machine-made sand used below is 1-3 mm. The coarse aggregate used below is limestone, wherein the mass ratio of limestone with a particle size of 20-25 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm, and limestone with a particle size of 3-5 mm is 8:8:3:1.

[0026] Example 1 A crack self-healing asphalt mixture, whose raw materials include: 10kg of 70# matrix asphalt, 1kg of carboxyl nitrile rubber, 1kg of copper fiber, 5kg of carbon composite basalt fiber, 1kg of dopamine, 10kg of limestone powder, 5kg of steel slag powder, 1kg of zinc stearate, 40kg of machine-made sand, and 150kg of coarse aggregate.

[0027] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1 mol / L hydrochloric acid for 1 hour, washed with water, dried, calcined at 500°C for 1 hour under nitrogen protection, and cooled to room temperature; 10 kg of the calcined product and 1 kg of 70# matrix asphalt were mixed, stirred evenly at 160°C, carbonized at 900°C for 5 hours under nitrogen protection, and cooled to room temperature.

[0028] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. Add dopamine to 50 kg of Tris-HCl solution with a pH value of 8-9, add carbon composite basalt fiber thereto, stir in the dark for 5 h at a stirring speed of 50 r / min, filter, wash with deionized water, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and machine-made sand at 120° C. for 1 h, respectively. Mix the dried coarse aggregate and the dried machine-made sand, add filler thereto twice while stirring, stir evenly, adjust the temperature to 160° C., add loaded fiber, copper fiber, and carboxyl nitrile rubber thereto while stirring, and mix for 10 s to obtain a premix. S4. Heat 70# base asphalt to 160°C, add premix into it while stirring, and mix for 1 minute.

[0029] Example 2 A crack self-healing asphalt mixture, whose raw materials include: 20kg of 70# matrix asphalt, 5kg of carboxylated nitrile rubber, 3kg of copper fiber, 15kg of carbon composite basalt fiber, 2kg of dopamine, 20kg of limestone powder, 15kg of steel slag powder, 2kg of zinc stearate, 80kg of machine-made sand, and 250kg of coarse aggregate.

[0030] Carbon composite basalt fiber is prepared by the following steps: basalt fiber is immersed in 1.5 mol / L hydrochloric acid for 2 hours, washed with water, dried, calcined at 600°C for 2 hours under nitrogen protection, and cooled to room temperature; 30 kg of calcined product and 5 kg of 70# matrix asphalt are mixed, stirred evenly at 170°C, carbonized at 1100°C for 10 hours under nitrogen protection, and cooled to room temperature.

[0031] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. dopamine was added to 100 kg of Tris-HCl solution with a pH value of 8-9, and carbon composite basalt fiber was added thereto. The mixture was stirred in the dark for 10 h at a stirring speed of 150 r / min, filtered, washed with deionized water, and vacuum dried to obtain loaded fibers. S3. Dry the coarse aggregate and machine-made sand at 130° C. for 2 h, respectively. Mix the dried coarse aggregate and the dried machine-made sand, add filler thereto twice under stirring, stir evenly, adjust the temperature to 170° C., add loaded fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring, and mix for 30 s to obtain a premix. S4. Heat 70# base asphalt to 170°C, add premix into it while stirring, and mix for 5 minutes.

[0032] Example 3 A crack self-healing asphalt mixture, whose raw materials include: 12kg of 70# matrix asphalt, 4kg of carboxylated nitrile rubber, 1.5kg of copper fiber, 12kg of carbon composite basalt fiber, 1.3kg of dopamine, 18kg of limestone powder, 7kg of steel slag powder, 1.7kg of zinc stearate, 50kg of machine-made sand, and 220kg of coarse aggregate.

[0033] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1.1 mol / L hydrochloric acid for 100 minutes, washed with water, dried, calcined at 520°C for 100 minutes under nitrogen protection, and cooled to room temperature; 15 kg of the calcined product and 4 kg of 70# matrix asphalt were mixed, stirred evenly at 162°C, carbonized at 1050°C for 7 hours under nitrogen protection, and cooled to room temperature.

[0034] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. Add dopamine to 90 kg of Tris-HCl solution with a pH value of 8-9, add carbon composite basalt fiber thereto, stir in the dark for 7 h at a stirring speed of 120 r / min, filter, wash with deionized water, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and machine-made sand at 122° C. for 100 min, respectively. Mix the dried coarse aggregate and machine-made sand, add filler thereto three times under stirring, stir evenly, adjust the temperature to 162° C., add loaded fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring, and mix for 25 s to obtain a premix. S4. Heat 70# base asphalt to 162°C, add premix into it while stirring, and mix for 4 minutes.

[0035] Example 4 A crack self-healing asphalt mixture, whose raw materials include: 18kg of 70# matrix asphalt, 2kg of carboxylated nitrile rubber, 2.5kg of copper fiber, 8kg of carbon composite basalt fiber, 1.7kg of dopamine, 12kg of limestone powder, 13kg of steel slag powder, 1.3kg of zinc stearate, 70kg of machine-made sand, and 180kg of coarse aggregate.

[0036] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1.3 mol / L hydrochloric acid for 80 minutes, washed with water, dried, calcined at 580°C for 80 minutes under nitrogen protection, and cooled to room temperature; 25 kg of the calcined product and 2 kg of 70# matrix asphalt were mixed, stirred evenly at 168°C, carbonized at 950°C for 9 hours under nitrogen protection, and cooled to room temperature.

[0037] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. dopamine was added to 70 kg of Tris-HCl solution with a pH value of 8-9, and carbon composite basalt fiber was added thereto. The mixture was stirred in the dark for 9 h at a stirring speed of 80 r / min, filtered, washed with deionized water, and vacuum dried to obtain loaded fibers. S3. Dry the coarse aggregate and machine-made sand at 128° C. for 80 min, respectively. Mix the dried coarse aggregate and the dried machine-made sand, add filler thereto three times under stirring, stir evenly, adjust the temperature to 168° C., add loaded fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring, and mix for 15 s to obtain a premix. S4. Heat 70# base asphalt to 168°C, add premix into it while stirring, and mix for 2 minutes.

[0038] Example 5 A crack self-healing asphalt mixture, whose raw materials include: 15kg of 70# matrix asphalt, 3kg of carboxylated nitrile rubber, 2kg of copper fiber, 10kg of carbon composite basalt fiber, 1.5kg of dopamine, 15kg of limestone powder, 10kg of steel slag powder, 1.5kg of zinc stearate, 60kg of machine-made sand, and 200kg of coarse aggregate.

[0039] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1.2 mol / L hydrochloric acid for 90 minutes, washed with water, dried, calcined at 550°C for 90 minutes under nitrogen protection, and cooled to room temperature; 20 kg of the calcined product and 3 kg of 70# matrix asphalt were mixed, stirred evenly at 165°C, carbonized at 1000°C for 8 hours under nitrogen protection, and cooled to room temperature.

[0040] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. Add dopamine to 80 kg of Tris-HCl solution with a pH value of 8-9, add carbon composite basalt fiber thereto, stir in the dark for 8 h at a stirring speed of 100 r / min, filter, wash with deionized water, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and machine-made sand at 125° C. for 90 min, respectively. Mix the dried coarse aggregate and machine-made sand, add filler thereto three times under stirring, stir evenly, adjust the temperature to 165° C., add loaded fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring, and mix for 20 s to obtain a premix. S4. Heat 70# base asphalt to 165°C, add premix into it while stirring, and mix for 3 minutes.

[0041] Comparative Example 1 A crack self-healing asphalt mixture, whose raw materials include: 15kg of 70# matrix asphalt, 3kg of carboxylated nitrile rubber, 2kg of copper fiber, 11.5kg of carbon composite basalt fiber, 15kg of limestone powder, 10kg of steel slag powder, 1.5kg of zinc stearate, 60kg of machine-made sand, and 200kg of coarse aggregate.

[0042] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1.2 mol / L hydrochloric acid for 90 minutes, washed with water, dried, calcined at 550°C for 90 minutes under nitrogen protection, and cooled to room temperature; 20 kg of the calcined product and 3 kg of 70# matrix asphalt were mixed, stirred evenly at 165°C, carbonized at 1000°C for 8 hours under nitrogen protection, and cooled to room temperature.

[0043] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. Dry the coarse aggregate and machine-made sand at 125° C. for 90 min, respectively. Mix the dried coarse aggregate and the dried machine-made sand, add filler thereto three times under stirring, stir evenly, adjust the temperature to 165° C., add carbon composite basalt fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring, and mix for 20 s to obtain a premix. S3. Heat 70# base asphalt to 165°C, add premix into it while stirring, and mix for 3 minutes.

[0044] Comparative Example 2 A crack self-healing asphalt mixture, whose raw materials include: 15kg of 70# matrix asphalt, 3kg of nitrile rubber, 2kg of copper fiber, 10kg of carbon composite basalt fiber, 1.5kg of dopamine, 15kg of limestone powder, 10kg of steel slag powder, 1.5kg of zinc stearate, 60kg of machine-made sand, and 200kg of coarse aggregate.

[0045] Carbon composite basalt fiber was prepared by the following steps: basalt fiber was immersed in 1.2 mol / L hydrochloric acid for 90 minutes, washed with water, dried, calcined at 550°C for 90 minutes under nitrogen protection, and cooled to room temperature; 20 kg of the calcined product and 3 kg of 70# matrix asphalt were mixed, stirred evenly at 165°C, carbonized at 1000°C for 8 hours under nitrogen protection, and cooled to room temperature.

[0046] The method for preparing the above-mentioned crack self-healing asphalt mixture comprises the following steps: S1. Mix limestone powder, steel slag powder, and zinc stearate evenly, dry to a moisture content of ≤0.5%, and grind to obtain a filler; S2. Add dopamine to 80 kg of Tris-HCl solution with a pH value of 8-9, add carbon composite basalt fiber thereto, stir in the dark for 8 h at a stirring speed of 100 r / min, filter, wash with deionized water, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and machine-made sand at 125° C. for 90 min, respectively. Mix the dried coarse aggregate and the dried machine-made sand, add filler thereto three times under stirring, stir evenly, adjust the temperature to 165° C., add load fiber, copper fiber, and nitrile rubber thereto under stirring, and mix for 20 s to obtain a premix. S4. Heat 70# base asphalt to 165°C, add premix into it while stirring, and mix for 3 minutes.

[0047] The properties of the asphalt mixtures obtained in Example 5 and Comparative Examples 1-2 were measured with reference to JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering".

[0048] like Figure 1 and Figure 2 As shown, the freeze-thaw splitting strength ratio, maximum bending tensile strain and rutting dynamic stability of the asphalt mixture obtained in Example 5 are the highest, while the flying loss is the least, which is better than that of comparative examples 1-2 (P < 0.05).

[0049] The asphalt mixtures obtained in Example 5 and Comparative Examples 1-2 were used to prepare samples of 70 mm × 70 mm × 10 mm. The self-healing test was conducted using a fracture strength recovery test. The specific experimental steps were as follows: (1) The specimen was placed in a constant temperature test chamber at -10°C for 4 h, and then subjected to a three-point bending failure test to obtain the initial failure load F0; (2) Place the broken specimen at a set distance under the coil and heat it until the surface temperature of the specimen reaches 120°C; (3) After heating for 120 seconds, stop heating and place the specimen at room temperature to cool; (4) Repeat step (1) to obtain the failure load F1 after induction heating healing.

[0050] The failure load ratio of the two bending tests before and after was calculated to obtain the strength recovery rate of the specimen; the crack widths of the two damaged specimens were recorded as L0 and L1 respectively, and the crack width ratio of the two bending tests before and after was calculated to obtain the crack healing rate of the specimen.

[0051] like Figure 3 As shown, the strength recovery rate and crack healing rate of the asphalt mixture obtained by Example 5 are the highest, which are better than those of Comparative Examples 1-2 (P < 0.05), showing excellent self-repairing performance.

[0052] The reason for the above results is that the present invention uses copper fibers to absorb crack expansion energy through plastic deformation, and forms a multi-level network structure at the crack with carbon composite mineral fibers loaded with dopamine. The polar groups on the surface of the loaded dopamine can cooperate with asphalt molecules to promote the migration of asphalt along the fiber surface to the crack area. At the same time, the capillary action of the fiber can accelerate the flow of asphalt and reduce the crack width. 2+It forms an ionic cross-linking network with the -COOH groups of carboxyl nitrile rubber, producing reversible fracture / recombination behavior under stress. When the crack expands, the cross-linking point breaks and consumes energy; after the temperature rises, the dynamic bond recombination realizes the self-repair of the crack. With the synergistic effect of the loaded dopamine, the crack self-repair performance is excellent. The present invention uses copper fiber and loaded fiber to form a multi-scale reinforcement system, in which the copper fiber bridges macro cracks and the loaded fiber inhibits the expansion of micro cracks. The glass transition temperature of the carboxyl nitrile rubber complements the low-temperature brittle point of asphalt, effectively reducing temperature shrinkage cracks, and having excellent freeze-thaw splitting strength. The combined effect is excellent in anti-cracking effect and good road performance.

[0053] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A crack self-healing asphalt mixture, characterized in that: The raw materials include, by mass, 10-20 parts of asphalt, 1-5 parts of carboxyl nitrile rubber, 1-3 parts of copper fiber, 5-15 parts of carbon composite mineral fiber, 1-2 parts of dopamine, 10-20 parts of limestone powder, 5-15 parts of steel slag powder, 1-2 parts of dispersant, 40-80 parts of fine aggregate, and 150-250 parts of coarse aggregate.

2. The crack self-healing asphalt mixture according to claim 1, characterized in that: The asphalt is 70# base asphalt.

3. The crack self-healing asphalt mixture according to claim 1, characterized in that: The dispersant is zinc stearate.

4. The crack self-healing asphalt mixture according to claim 1, characterized in that: The aspect ratio of copper fiber is 200-250.

5. The crack self-healing asphalt mixture according to claim 1, characterized in that: The fine aggregate is machine-made sand with a particle size of 1-3 mm.

6. The crack self-healing asphalt mixture according to claim 1, characterized in that: The coarse aggregate is limestone with a particle size of 3-25 mm; wherein the mass ratio of limestone with a particle size of 20-25 mm, limestone with a particle size of 10-20 mm, limestone with a particle size of 5-10 mm and limestone with a particle size of 3-5 mm is 5-10:5-10:1-4:1-2.

7. The crack self-healing asphalt mixture according to claim 1, characterized in that: The carbon composite mineral fiber is prepared by the following steps: soaking the mineral fiber in hydrochloric acid for 1-2 hours, washing with water, drying, calcining at 500-600°C for 1-2 hours under nitrogen protection, and cooling to room temperature; mixing the calcined product and asphalt, stirring evenly at 160-170°C, carbonizing at 900-1100°C for 5-10 hours under nitrogen protection, and cooling to room temperature.

8. The crack self-healing asphalt mixture according to claim 7, characterized in that: The concentration of hydrochloric acid is 1-1.5 mol / L; the mass ratio of the calcined product to the asphalt is 10-30:1-5.

9. A method for preparing the crack self-healing asphalt mixture according to any one of claims 1 to 8, characterized in that: The steps include: S1. Mix limestone powder, steel slag powder and dispersant, dry and crush to obtain filler; S2. Add dopamine to a Tris-HCl solution with a pH of 8-9, add carbon composite mineral fiber thereto, stir in the dark for 5-10 hours, filter, wash, and vacuum dry to obtain loaded fiber; S3. Dry the coarse aggregate and the fine aggregate separately, mix the dried coarse aggregate and the dried fine aggregate, add filler thereto in 2-3 times under stirring, stir evenly, adjust the temperature to 160-170° C., add load fiber, copper fiber, and carboxyl nitrile rubber thereto under stirring and mix for 10-30 seconds to obtain a premix; S4. Heat the asphalt to 160-170°C, add the premix into the asphalt while stirring, and mix for 1-5 minutes.

10. The method for preparing crack self-healing asphalt mixture according to claim 9, characterized in that: In S1, the mixture is dried to a moisture content of ≤0.5%.

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