A colored mixture for preventive maintenance of asphalt pavement and its preparation method

Abstract

The present invention discloses a colored mixture for preventive maintenance of asphalt pavement and a preparation method thereof, relating to the technical field of colored asphalt mixtures. In this application, a modified styrene-butadiene-styrene block copolymer (SBS), modified carbon nanotubes and inorganic pigments are used to prepare a modifier for colored ultra-thin wearing surface. Among them, through the thiol-ene click chemical reaction, 3-mercaptopropionic acid reacts with the double bonds in SBS for modification, so that carboxyl groups are introduced onto it, which can in-situ coordinate with metal oxides in inorganic pigments to generate salt bonds, and then form a crosslinked network, which can effectively improve the mechanical properties of the material and eliminate a large number of unsaturated double bonds existing therein, making it not easy to age.

Description

Technical Field

[0001] The present invention relates to the technical field of colored asphalt mixtures, and specifically to a colored mixture for preventive maintenance of asphalt pavements and a preparation method thereof. Background Art

[0002] With the development of social economy, people have higher and higher requirements for travel. Due to its good recognition and beautification effects, colored pavements have been widely used in urban slow systems and landscape roads in recent years. Currently, colored pavements are mainly divided into three types: colored asphalt concrete, colored spraying, and color slurry seal coat. The mechanical properties of colored spraying are relatively low and can only be used for landscape footpaths in parks; the mechanical properties of color slurry seal coat are excellent, but the cost is relatively high, and it is only used for road turning, downhill, or sections with a reminder function. Therefore, the mainstream colored pavement is still colored asphalt concrete. Colored asphalt concrete is a pavement formed by mixing and paving crushed stones, decolorized asphalt, and color powder. From the overall application effect in recent years, the durability of decolorized asphalt is poor, and the lifespan of colored pavements is short. Generally, serious net cracks and potholes appear within 3 - 5 years, affecting the comfort of road traffic. There is an urgent need to maintain these colored pavements, but the road management department is a bit at a loss. If the existing colored pavement is milled off, only colored asphalt pavement can be paved, and the same problem will still occur after 3 - 5 years, with huge investment. If it is replaced with an ordinary asphalt concrete pavement, the existing urban slow system will return to its previous state, and the improvement effect of urban road beautification in recent years will be wasted. In view of this situation, this patent develops a colored ultra-thin overlay technology and its additives for preventive maintenance of existing colored asphalt pavements. By paving about 2 cm of colored ultra-thin asphalt mixture on the existing pavement, the existing pavement can be repaired while ensuring the colored effect of the pavement. Summary of the Invention

[0003] The purpose of the present invention is to provide a colored mixture for preventive maintenance of asphalt pavements and a preparation method thereof to solve the problems existing in the prior art.

[0004] To solve the above technical problems, the present invention provides the following technical solutions:

[0005] A colored mixture for preventive maintenance of asphalt pavements, wherein the weight parts of each component of the colored mixture are: 55 - 70 parts of coarse aggregate, 20 - 50 parts of fine aggregate, 5 - 10 parts of limestone powder, 4.5 - 6 parts of asphalt, and 2 - 6 parts of colored ultra-thin overlay modifier;

[0006] Among them, the specification of the coarse aggregate is 3 - 5 mm, and the specification of the fine aggregate is 0 - 3 mm; the asphalt is 70# or 90# heavy traffic road petroleum asphalt;

[0007] The weight parts of each component in the colored ultra-thin wearing surface modifier are as follows: 90-100 parts of inorganic pigment, 120-150 parts of modified styrene-butadiene-styrene block copolymer, 1-5 parts of modified carbon nanotubes, and 0-30 parts of plasticizer;

[0008] The modified carbon nanotubes are obtained by grafting reaction between modified diamine-terminated polydimethylsiloxane and acyl chloride carbon nanotubes; wherein, the modified diamine-terminated polydimethylsiloxane is prepared by chain extension reaction of diamine-terminated polydimethylsiloxane and 2,6-pyridine dicarbonyl chloride.

[0009] Preferably, the modified styrene-butadiene-styrene block copolymer is modified by 3-mercaptopropionic acid through thiol-ene click chemical reaction, so that 3-mercaptopropionic acid reacts with the double bond in the styrene-butadiene-styrene block copolymer to modify the styrene-butadiene-styrene block copolymer, and the modified styrene-butadiene-styrene block copolymer is obtained.

[0010] A preparation method of a colored mixture for preventive maintenance of asphalt pavement includes the following preparation steps:

[0011] S1. Weigh 90-100 parts of inorganic pigment, 120-150 parts of modified styrene-butadiene-styrene block copolymer, 1-5 parts of modified carbon nanotubes, and 0-30 parts of plasticizer, and add them to a two-roll mill. Under the condition of a temperature of 130-140 °C, mix for 5-10 min and then discharge. After cooling, cut into pellets to obtain the colored ultra-thin wearing surface modifier; the modified carbon nanotubes include the following steps: Add acyl chloride carbon nanotubes to N,N-dimethylformamide which is 15-20 times the mass of the acyl chloride carbon nanotubes, ultrasonically disperse for 15-20 min, and under the condition of a temperature of 0-5 °C, uniformly dropwise add a solution of modified diamine-terminated polydimethylsiloxane which is 5-7 times the mass of the acyl chloride carbon nanotubes at a speed of 2-3 mL / min. After the dropping is completed, under the condition of a temperature of 25-35 °C, stir for 24-28 h. After the stirring is completed, let it stand for filtration, and dry and grind the filtered product to obtain the modified carbon nanotubes;

[0012] S2. Weigh 55-70 parts of coarse aggregate, 20-50 parts of fine aggregate, 5-10 parts of limestone powder, 4.5-6 parts of asphalt, and 2-6 parts of colored ultra-thin wearing surface modifier. After stirring and heating the coarse aggregate and fine aggregate to 150-170 °C, add the colored ultra-thin wearing surface modifier and stir for 5-15 s, then add asphalt and limestone powder, and continue to stir for 30-60 s to obtain the colored mixture.

[0013] Preferably, the modified styrene-butadiene-styrene block copolymer is prepared by the following steps: adding styrene-butadiene-styrene block copolymer into cyclohexane which is 20-22 times the mass of the styrene-butadiene-styrene block copolymer, stirring evenly, adding azobisisobutyronitrile which is 0.5%-0.75% times the mass of the styrene-butadiene-styrene block copolymer, under the condition of nitrogen protection at a temperature of 0-5 °C, dropping 3-mercaptopropionic acid which is 0.7-0.9 times the mass of the styrene-butadiene-styrene block copolymer. After the dropping is completed, reacting for 10-15 min, then heating to 55-65 °C and reacting for 12-14 h. After the reaction is completed, adding absolute ethanol which is 2-3 times the mass of cyclohexane, stirring and then filtering. The filtered product is washed 3-5 times with absolute ethanol and deionized water respectively, and then dried to obtain the modified styrene-butadiene-styrene block copolymer.

[0014] Preferably, the modified diamine-terminated polydimethylsiloxane solution is prepared by the following steps: adding modified diamine-terminated polydimethylsiloxane into N,N-dimethylformamide which is 12-14 times the mass of the modified diamine-terminated polydimethylsiloxane, stirring evenly to prepare a modified diamine-terminated polydimethylsiloxane solution for standby.

[0015] Preferably, the modified diamine-terminated polydimethylsiloxane is prepared by the following steps: under the condition of nitrogen protection, adding diamine-terminated polydimethylsiloxane into dichloromethane which is 10-12 times the mass of the diamine-terminated polydimethylsiloxane, stirring to dissolve, under the condition of a temperature of 0-5 °C, adding triethylamine which is 0.03-0.05 times the mass of the diamine-terminated polydimethylsiloxane, stirring and reacting for 2-2.5 h. After the stirring is completed, dropping a 2,6-pyridinedicarbonyl chloride solution which is 0.3-0.5 times the mass of the diamine-terminated polydimethylsiloxane at a constant speed of 5-8 mL / min. After the dropping is completed, under the condition of a temperature of 0-5 °C, stirring and reacting for 2-2.5 h. After the stirring is completed, under the condition of a temperature of 25-35 °C, stirring and reacting for 24-26 h. After the reaction is completed, rotary evaporating to remove the dichloromethane solvent, and after the rotary evaporation is completed, drying under vacuum to obtain the modified diamine-terminated polydimethylsiloxane.

[0016] Preferably, the 2,6-pyridinedicarbonyl chloride solution is prepared by the following process: adding 2,6-pyridinedicarbonyl chloride into dichloromethane which is 10-12 times the mass of the 2,6-pyridinedicarbonyl chloride, stirring evenly to prepare a 2,6-pyridinedicarbonyl chloride solution for standby.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0018] This application uses a modified styrene-butadiene-styrene block copolymer (SBS), modified carbon nanotubes, and inorganic pigments to prepare a color ultra-thin wearing surface modifier. Among them, based on the thiol-ene click chemical reaction, 3-mercaptopropionic acid reacts with the double bonds in SBS for modification, and carboxyl groups are introduced onto it, which can in-situ coordinate with metal oxides in inorganic pigments to generate salt bonds, thereby forming a crosslinked network, effectively improving the mechanical properties of the material, and eliminating a large number of unsaturated double bonds therein, making it not easy to age;

[0019] And modified carbon nanotubes are also used therein. A modified diamine-terminated polydimethylsiloxane is prepared by the chain extension reaction of diamine-terminated polydimethylsiloxane and 2,6-pyridine dicarbonyl chloride, and then a grafting reaction is carried out between the modified diamine-terminated polydimethylsiloxane and acyl chloride-functionalized carbon nanotubes. Among them, a three-dimensional network structure is formed by SBS and carbon nanotubes, and the particles formed by SBS can be evenly dispersed in asphalt. Incorporating SBS can also improve the low-temperature performance of asphalt. And the pyridine incorporated therein forms reversible metal coordination bonds with metal ions such as iron contained in inorganic pigments, while the remaining amino groups in the diamine-terminated polydimethylsiloxane form hydrogen bond hybrid crosslinked networks with the carboxyl groups existing in the modified SBS, improving the mechanical properties of the final product. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0021] Example 1

[0022] S1. Add 2,6-pyridinedicarbonyl chloride to dichloromethane which is 10 times the mass of 2,6-pyridinedicarbonyl chloride, stir evenly to prepare a 2,6-pyridinedicarbonyl chloride solution for standby; Under the protection of nitrogen, add diamine-terminated polydimethylsiloxane to dichloromethane which is 10 times the mass of diamine-terminated polydimethylsiloxane, stir to dissolve, and at a temperature of 0 °C, add triethylamine which is 0.03 times the mass of diamine-terminated polydimethylsiloxane, stir and react for 2 h. After stirring is completed, dropwise add the 2,6-pyridinedicarbonyl chloride solution which is 0.3 times the mass of diamine-terminated polydimethylsiloxane at a uniform speed of 5 mL / min. After the dropwise addition is completed, at a temperature of 0 °C, stir and react for 2 h. After stirring is completed, at a temperature of 25 °C, stir and react for 24 h. After the reaction is completed, rotary evaporate to remove the dichloromethane solvent, and after rotary evaporation is completed, dry in vacuum to obtain modified diamine-terminated polydimethylsiloxane; Add the modified diamine-terminated polydimethylsiloxane to N,N-dimethylformamide which is 12 times the mass of the modified diamine-terminated polydimethylsiloxane, stir evenly to prepare a modified diamine-terminated polydimethylsiloxane solution for standby;

[0023] S2. Add acyl chloride-functionalized carbon nanotubes to N,N-dimethylformamide which is 15 times the mass of acyl chloride-functionalized carbon nanotubes, ultrasonically disperse for 15 min, and at a temperature of 0 °C, dropwise add the modified diamine-terminated polydimethylsiloxane solution which is 5 times the mass of acyl chloride-functionalized carbon nanotubes at a uniform speed of 2 mL / min. After the dropwise addition is completed, at a temperature of 25 °C, stir for 24 h. After stirring is completed, let it stand for filtration, and dry and grind the filtered product to obtain modified carbon nanotubes;

[0024] S3. Add styrene-butadiene-styrene block copolymer to cyclohexane which is 20 times the mass of styrene-butadiene-styrene block copolymer, stir evenly and then add azobisisobutyronitrile which is 0.5% times the mass of styrene-butadiene-styrene block copolymer. Under the condition of nitrogen protection at a temperature of 0 °C, dropwise add 3-mercaptopropionic acid which is 0.7 times the mass of styrene-butadiene-styrene block copolymer. After the dropwise addition is completed, after reacting for 10 min, raise the temperature to 55 °C and react for 12 h. After the reaction is completed, add anhydrous ethanol which is 2 times the mass of cyclohexane, stir and then filter. Wash the filtered product 3 times with anhydrous ethanol and deionized water respectively, and then dry to obtain modified styrene-butadiene-styrene block copolymer;

[0025] S4. Weigh by weight parts, 90 parts of inorganic pigment, 120 parts of modified styrene-butadiene-styrene block copolymer, 1 part of modified carbon nanotubes and 0 parts of plasticizer, and add them to a two-roll mill. At a temperature of 130 °C, knead for 5 min and then discharge. After cooling, pelletize to obtain a color ultra-thin surface modifier;

[0026] S5. Weigh by parts by weight, 55 parts of coarse aggregate, 20 parts of fine aggregate, 5 parts of limestone powder, 4.5 parts of asphalt and 2 parts of color ultra-thin wearing surface modifier. After stirring and heating the coarse aggregate and fine aggregate to 150 °C, then add the color ultra-thin wearing surface modifier and stir for 5 s, then add asphalt and limestone powder, and continue to stir for 30 s to obtain a color mixture.

[0027] Example 2

[0028] S1. Add 2,6-pyridinedicarbonyl chloride to dichloromethane which is 11 times the mass of 2,6-pyridinedicarbonyl chloride, stir evenly to prepare a 2,6-pyridinedicarbonyl chloride solution for standby; under the protection of nitrogen, add diamine-terminated polydimethylsiloxane to dichloromethane which is 11 times the mass of diamine-terminated polydimethylsiloxane, stir to dissolve, and at a temperature of 2.5 °C, add triethylamine which is 0.04 times the mass of diamine-terminated polydimethylsiloxane, stir and react for 2.25 h. After the stirring is completed, dropwise add the 2,6-pyridinedicarbonyl chloride solution which is 0.4 times the mass of diamine-terminated polydimethylsiloxane at a constant speed of 6.5 mL / min. After the dropping is completed, at a temperature of 2.5 °C, stir and react for 2.25 h. After the stirring is completed, at a temperature of 30 °C, stir and react for 25 h. After the reaction is completed, rotary evaporate to remove the dichloromethane solvent. After the rotary evaporation is completed, vacuum dry to obtain modified diamine-terminated polydimethylsiloxane; add the modified diamine-terminated polydimethylsiloxane to N,N-dimethylformamide which is 13 times the mass of the modified diamine-terminated polydimethylsiloxane, stir evenly to prepare a modified diamine-terminated polydimethylsiloxane solution for standby;

[0029] S2. Add acyl chloride-functionalized carbon nanotubes to N,N-dimethylformamide which is 17.5 times the mass of acyl chloride-functionalized carbon nanotubes, ultrasonically disperse for 17.5 min, and at a temperature of 2.5 °C, dropwise add the modified diamine-terminated polydimethylsiloxane solution which is 6 times the mass of acyl chloride-functionalized carbon nanotubes at a constant speed of 2.5 mL / min. After the dropping is completed, at a temperature of 30 °C, stir for 26 h. After the stirring is completed, let it stand and filter, and dry and grind the filtered product to obtain modified carbon nanotubes;

[0030] S3. Add styrene-butadiene-styrene block copolymer to cyclohexane which is 21 times the mass of the styrene-butadiene-styrene block copolymer. After stirring evenly, add azobisisobutyronitrile which is 0.625% of the mass of the styrene-butadiene-styrene block copolymer. Under the condition of nitrogen protection at a temperature of 2.5 °C, dropwise add 3-mercaptopropionic acid which is 0.8 times the mass of the styrene-butadiene-styrene block copolymer. After the dropwise addition is completed, react for 12.5 min, then raise the temperature to 60 °C and react for 13 h. After the reaction is completed, add anhydrous ethanol which is 2.5 times the mass of cyclohexane, stir and then filter. Wash the filtered product 4 times with anhydrous ethanol and deionized water respectively, and then dry to obtain the modified styrene-butadiene-styrene block copolymer;

[0031] S4. Weigh by weight parts: 95 parts of inorganic pigment, 135 parts of modified styrene-butadiene-styrene block copolymer, 3 parts of modified carbon nanotube and 15 parts of plasticizer, and add them to a two-roll mill. Under the condition of a temperature of 135 °C, knead for 7.5 min and then discharge. After cooling, pelletize to obtain the color ultra-thin surface modification agent;

[0032] S5. Weigh by weight parts: 62.5 parts of coarse aggregate, 35 parts of fine aggregate, 7.5 parts of limestone powder, 5.25 parts of asphalt and 4 parts of color ultra-thin surface modification agent. After stirring and heating the coarse aggregate and fine aggregate to 160 °C, add the color ultra-thin surface modification agent and stir for 10 s, then add asphalt and limestone powder, and continue to stir for 45 s to obtain the color mixture.

[0033] Example 3

[0034] S1. Add 2,6-pyridinedicarbonyl chloride to dichloromethane which is 12 times the mass of 2,6-pyridinedicarbonyl chloride, stir evenly, and prepare a 2,6-pyridinedicarbonyl chloride solution for standby; Under the condition of nitrogen protection, add diamine-terminated polydimethylsiloxane to dichloromethane which is 12 times the mass of diamine-terminated polydimethylsiloxane, stir and dissolve it. Under the condition of a temperature of 5 °C, add triethylamine which is 0.05 times the mass of diamine-terminated polydimethylsiloxane, stir and react for 2.5 h. After the stirring is completed, dropwise add the 2,6-pyridinedicarbonyl chloride solution which is 0.5 times the mass of diamine-terminated polydimethylsiloxane at a constant speed of 8 mL / min. After the dropwise addition is completed, under the condition of a temperature of 5 °C, stir and react for 2.5 h. After the stirring is completed, under the condition of a temperature of 35 °C, stir and react for 26 h. After the reaction is completed, rotary evaporate to remove the dichloromethane solvent. After the rotary evaporation is completed, dry under vacuum to obtain the modified diamine-terminated polydimethylsiloxane; Add the modified diamine-terminated polydimethylsiloxane to N,N-dimethylformamide which is 14 times the mass of the modified diamine-terminated polydimethylsiloxane, stir evenly, and prepare a modified diamine-terminated polydimethylsiloxane solution for standby;

[0035] S2. Add the acyl chloride-functionalized carbon nanotubes to N,N-dimethylformamide which is 20 times the mass of the acyl chloride-functionalized carbon nanotubes, and ultrasonically disperse for 20 min. Under the condition of a temperature of 5 °C, dropwise add the solution of the modified diamine-terminated polydimethylsiloxane which is 7 times the mass of the acyl chloride-functionalized carbon nanotubes at a uniform speed of 3 mL / min. After the dropwise addition is completed, under the condition of a temperature of 35 °C, stir for 28 h. After the stirring is completed, let it stand for filtration, and dry and grind the filtered product to obtain the modified carbon nanotubes;

[0036] S3. Add the styrene-butadiene-styrene block copolymer to cyclohexane which is 22 times the mass of the styrene-butadiene-styrene block copolymer, stir evenly, and then add azobisisobutyronitrile which is 0.75% of the mass of the styrene-butadiene-styrene block copolymer. Under the condition of a temperature of 5 °C and nitrogen protection, dropwise add 3-mercaptopropionic acid which is 0.9 times the mass of the styrene-butadiene-styrene block copolymer. After the dropwise addition is completed, react for 15 min, then raise the temperature to 65 °C and react for 14 h. After the reaction is completed, add anhydrous ethanol which is 3 times the mass of cyclohexane, stir and then filter. Wash the filtered product 5 times with anhydrous ethanol and deionized water respectively, and then dry to obtain the modified styrene-butadiene-styrene block copolymer;

[0037] S4. Weigh by weight parts: 100 parts of inorganic pigment, 150 parts of modified styrene-butadiene-styrene block copolymer, 5 parts of modified carbon nanotubes, and 30 parts of plasticizer, and add them to a two-roll mill. Under the condition of a temperature of 140 °C, knead for 10 min and then discharge. After cooling, pelletize to obtain the colored ultra-thin surface modifier;

[0038] S5. Weigh by weight parts: 70 parts of coarse aggregate, 50 parts of fine aggregate, 10 parts of limestone powder, 6 parts of asphalt, and 6 parts of colored ultra-thin surface modifier. Stir and heat the coarse aggregate and fine aggregate to 170 °C, then add the colored ultra-thin surface modifier and stir for 15 s, then add the asphalt and limestone powder, and continue to stir for 60 s to obtain the colored mixture.

[0039] Example 4

[0040] The difference from Example 2 is only in step S2: Add the acyl chloride-functionalized carbon nanotubes to N,N-dimethylformamide which is 17.5 times the mass of the acyl chloride-functionalized carbon nanotubes, and ultrasonically disperse for 17.5 min. Under the condition of a temperature of 2.5 °C, dropwise add the solution of the diamine-terminated polydimethylsiloxane which is 6 times the mass of the acyl chloride-functionalized carbon nanotubes at a uniform speed of 2.5 mL / min. After the dropwise addition is completed, under the condition of a temperature of 30 °C, stir for 26 h. After the stirring is completed, let it stand for filtration, and dry and grind the filtered product to obtain the modified carbon nanotubes; Add the diamine-terminated polydimethylsiloxane to N,N-dimethylformamide which is 13 times the mass of the diamine-terminated polydimethylsiloxane, stir evenly, and prepare the solution of the diamine-terminated polydimethylsiloxane for standby;

[0041] Example 5

[0042] The difference from Example 2 is only in step S4: Weigh by weight parts, 95 parts of inorganic pigment, 135 parts of styrene-butadiene-styrene block copolymer, 3 parts of modified carbon nanotubes and 15 parts of plasticizer, and add them to a two-roll open mill. Under the condition of a temperature of 135°C, mix for 7.5 min and then discharge. After cooling, pelletize to obtain a colored ultra-thin surface modifier;

[0043] Example 6

[0044] The difference from Example 2 is only in step S4: Weigh by weight parts, 95 parts of inorganic pigment, 135 parts of modified styrene-butadiene-styrene block copolymer, 3 parts of carbon nanotubes and 15 parts of plasticizer, and add them to a two-roll open mill. Under the condition of a temperature of 135°C, mix for 7.5 min and then discharge. After cooling, pelletize to obtain a colored ultra-thin surface modifier;

[0045] Example 7

[0046] The difference from Example 2 is only in step S4: Weigh by weight parts, 95 parts of inorganic pigment, 135 parts of styrene-butadiene-styrene block copolymer, 3 parts of carbon nanotubes and 15 parts of plasticizer, and add them to a two-roll open mill. Under the condition of a temperature of 135°C, mix for 7.5 min and then discharge. After cooling, pelletize to obtain a colored ultra-thin surface modifier;

[0047] Example 8

[0048] The difference from Example 2 is only in step S5: Weigh by weight parts, 62.5 parts of coarse aggregate, 35 parts of fine aggregate, 7.5 parts of limestone powder and 5.25 parts of asphalt. After stirring and heating the coarse aggregate and fine aggregate to 160°C, then add asphalt and limestone powder and continue to stir for 45 s to obtain a colored mixture;

[0049] For the above Examples 1 to 8, in accordance with the asphalt test standards of "Test Regulations for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20-2011): Penetration TO604-2011; Immersion Marshall Test T0709-2000; Freeze-Thaw Split Test T0729-2000; conduct experiments; the experimental results are shown in Table 1 below;

[0050] Table 1

[0051]

[0052] From the comparison of the experimental data of Examples 1 to 3 in Table 1, it can be found that the colored mixture prepared by the present invention has good low-temperature resistance;

[0053] In Examples 4 to 7, the performance gradually decreases. In Example 4, due to the lack of pyridine, in Example 5, SBS is not modified, in Example 6, carbon nanotubes are not modified, and in Example 7, neither SBS nor carbon nanotubes are modified. It can be seen from the data that the performance of the colored mixture gradually decreases, and the decrease is most obvious in Example 8, which is caused by the lack of a colored ultra-thin wearing surface modifier;

[0054] For the above Examples 1 to 8, splitting tensile strength tests are carried out. The tests are divided into three categories according to the asphalt test standards in the "Test Procedures for Bitumen and Bituminous Mixtures in Highway Engineering" (JTG E20-2011): the splitting test of asphalt mixture T0716-2011. The first category is to test the splitting tensile strength of the initial sample. The second category is to carry out ultraviolet aging. A 1000W high-pressure mercury lamp is used to simulate ultraviolet irradiation for 100h, and then the splitting tensile strength test is carried out. The third category is to test the low-temperature self-healing performance. A cut is made in the middle of the specimen with a blade, and the damaged sample is allowed to self-heal at 0°C for 1h, and then the splitting tensile strength test is carried out; among them, the anti-aging performance = splitting tensile strength after ultraviolet aging / initial splitting tensile strength; the low-temperature self-healing performance = splitting tensile strength after low-temperature self-healing / initial splitting tensile strength; the test results are shown in Table 2 below;

[0055] Table 2

[0056]

[0057] From the comparison of the experimental data of Examples 1 to 3 in Table 2, it can be found that the colored mixture prepared by the present invention has good anti-aging performance and low-temperature self-healing performance;

[0058] In Examples 5 and 7, the anti-aging performance decreases rapidly. The main reason is that there are a large number of double bonds on unmodified SBS, resulting in a decrease in its anti-aging performance; and except for Example 5, the low-temperature self-healing ability decreases rapidly, mainly due to the lack of reversible metal coordination bonds.

[0059] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claimed rights.

Claims

1. A color mixture for preventive maintenance of asphalt pavement, characterized in that: The weight proportions of the components of the color mixture are: 55-70 parts of coarse aggregate, 20-50 parts of fine aggregate, 5-10 parts of limestone powder, 4.5-6 parts of asphalt and 2-6 parts of color ultra-thin coating modifier; The coarse aggregate has a specification of 3-5 mm, the fine aggregate has a specification of 0-3 mm; the asphalt is 70# or 90# heavy road petroleum asphalt; The weight proportions of the components in the colored ultra-thin coating modifier are: 90-100 parts of inorganic pigment, 120-150 parts of modified styrene-butadiene-styrene block copolymer, 1-5 parts of modified carbon nanotubes and 0-30 parts of plasticizer; The modified carbon nanotubes are obtained by grafting modified diamine-terminated polydimethylsiloxane with acyl chloride carbon nanotubes; wherein the diamine-terminated polydimethylsiloxane is subjected to a chain extension reaction with 2,6-pyridine dicarbonyl chloride to prepare the modified diamine-terminated polydimethylsiloxane.

2. The color mixture for preventive maintenance of asphalt pavement according to claim 1, characterized in that: The modified styrene-butadiene-styrene block copolymer adopts 3-mercaptopropionic acid through a mercapto-ene click chemical reaction, so that 3-mercaptopropionic acid reacts with double bonds in the styrene-butadiene-styrene block copolymer to modify the styrene-butadiene-styrene block copolymer, thereby obtaining the modified styrene-butadiene-styrene block copolymer.

3. A method for preparing a color mixture for preventive maintenance of asphalt pavement, applied to the color mixture for preventive maintenance of asphalt pavement in claim 1, characterized in that: The method comprises the following preparation steps: S1, weighing 90-100 parts of inorganic pigment, 120-150 parts of modified styrene-butadiene-styrene block copolymer, 1-5 parts of modified carbon nanotubes and 0-30 parts of plasticizer, and adding them into a double-roll mill, mixing for 5-10 minutes at a temperature of 130-140°C, discharging, cooling and pelletizing to obtain a colored ultra-thin coating modifier; the modified carbon nanotubes include the following steps: adding acyl chloride carbon nanotubes to acyl chloride carbon nanotubes; In N, N-dimethylformamide (15 to 20 times the mass of the carbon nanotubes), ultrasonic dispersion is performed for 15 to 20 minutes. At a temperature of 0 to 5°C, a modified diamine-terminated polydimethylsiloxane solution (5 to 7 times the mass of the acyl chloride carbon nanotubes) is uniformly added at a rate of 2 to 3 mL / min. After the addition is completed, the mixture is stirred for 24 to 28 hours at a temperature of 25 to 35°C. After the stirring is completed, the mixture is allowed to stand and filtered, and the filtered product is dried and ground to obtain modified carbon nanotubes. S2. Weigh 55-70 parts of coarse aggregate, 20-50 parts of fine aggregate, 5-10 parts of limestone powder, 4.5-6 parts of asphalt and 2-6 parts of colored ultra-thin surface modifier. Stir and heat the coarse aggregate and fine aggregate to 150-170°C, then add the colored ultra-thin surface modifier and stir for 5-15s, then add asphalt and limestone powder, and continue stirring for 30-60s to obtain a colored mixture.

4. The method for preparing a colored mixture for preventive maintenance of asphalt pavement according to claim 3, characterized in that: The modified styrene-butadiene-styrene block copolymer comprises the following preparation steps: adding the styrene-butadiene-styrene block copolymer to cyclohexane with a mass of 20 to 22 times that of the styrene-butadiene-styrene block copolymer, stirring evenly, adding azobisisobutyronitrile with a mass of 0.5% to 0.75% of that of the styrene-butadiene-styrene block copolymer, dripping 3-mercaptopropionic acid with a mass of 0.7 to 0.9 times that of the styrene-butadiene-styrene block copolymer at a temperature of 0 to 5° C. and under nitrogen protection, reacting for 10 to 15 minutes after the dripping is completed, heating to 55 to 65° C. and reacting for 12 to 14 hours, adding anhydrous ethanol with a mass of 2 to 3 times that of the cyclohexane after the reaction is completed, stirring, filtering, washing the filtered product with anhydrous ethanol and deionized water for 3 to 5 times respectively, and drying to obtain the modified styrene-butadiene-styrene block copolymer.

5. The method for preparing a colored mixture for preventive maintenance of asphalt pavement according to claim 3, characterized in that: The modified diamine-terminated polydimethylsiloxane solution comprises the following preparation steps: adding the modified diamine-terminated polydimethylsiloxane to N,N-dimethylformamide with a mass 12 to 14 times that of the modified diamine-terminated polydimethylsiloxane, stirring evenly, preparing a modified diamine-terminated polydimethylsiloxane solution for standby use.

6. The method for preparing a colored mixture for preventive maintenance of asphalt pavement according to claim 5, characterized in that: The modified diamino-terminated polydimethylsiloxane comprises the following preparation steps: under nitrogen protection, adding diamino-terminated polydimethylsiloxane to dichloromethane with a mass of 10 to 12 times that of the diamino-terminated polydimethylsiloxane, stirring and dissolving, adding triethylamine with a mass of 0.03 to 0.05 times that of the diamino-terminated polydimethylsiloxane at a temperature of 0 to 5° C., stirring and reacting for 2 to 2.5 hours, adding 2,6-pyridinedicarbonyl chloride solution with a mass of 0.3 to 0.5 times that of the diamino-terminated polydimethylsiloxane at a uniform speed of 5 to 8 mL / min after the stirring is completed, stirring and reacting for 2 to 2.5 hours at a temperature of 0 to 5° C., stirring and reacting for 24 to 26 hours at a temperature of 25 to 35° C. after the reaction is completed, removing the dichloromethane solvent by rotary evaporation, and vacuum drying after the rotary evaporation to obtain the modified diamino-terminated polydimethylsiloxane.

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