Conductive aggregate and preparation method thereof, asphalt mixture and preparation method and application thereof

Abstract

The invention belongs to the technical field of asphalt mixtures, and particularly relates to conductive aggregate and a preparation method thereof, an asphalt mixture and a preparation method and application of the asphalt mixture. The conductive aggregate comprises an aggregate matrix and a conductive film, wherein the conductive film is coated on the surface of the aggregate matrix; the conductive thin film comprises an adhesive and a carbon nanomaterial which forms a three-dimensional conductive network on the surface of the aggregate matrix; the thickness of the conductive film is 20 [mu] m-70 [mu] m. The conductive thin film is coated on the surface of the aggregate matrix, and the thickness of the conductive thin film is only 20-70 [mu] m, so that the particle size of the conductive aggregate is not greatly different from that of the aggregate collective, and the asphalt mixture obtained by mixing the conductive aggregate with the asphalt matrix can improve the conductivity of the conductive aggregate on the premise of keeping the physical and chemical properties of the asphalt matrix. And the phenomenon that the carbon nanomaterial is easily agglomerated when being directly mixed with the asphalt matrix as a conductive phase is effectively prevented.

Description

Technical Field

[0001] The present application belongs to the technical field of asphalt mixtures, and in particular, relates to a conductive aggregate and a preparation method thereof, an asphalt mixture and a preparation method and application thereof. Background Art

[0002] Asphalt mixture is composed of asphalt, aggregate and filler, among which aggregate mainly plays a role of skeleton support, and filler and asphalt are used to bond aggregate to form strength. Due to its low price, high degree of paving automation and excellent performance, it is widely used in transportation infrastructure, especially high-grade road construction. In recent years, road engineering has gradually developed in the direction of sustainability and intelligence; among them, the development and application of conductive asphalt and conductive asphalt mixture has attracted great attention in the scientific research and industrial circles. Conductive asphalt mixture has many potential application scenarios, such as self-healing performance improvement, electromagnetic shielding, pavement snow melting and deicing, road weighing and traffic volume monitoring. The above-mentioned multifunctional / intelligent characteristics of asphalt mixture will help improve the performance and safety of road use, as well as save maintenance / maintenance costs during the life cycle, and have important economic and environmental value.

[0003] The method for preparing conductive asphalt concrete is usually to directly introduce a conductive phase into the asphalt matrix or to use conductive aggregates instead of natural aggregates. Among them, the former is most commonly used to directly introduce carbon-based materials such as carbon black, carbon nanotubes, carbon fibers and graphene into asphalt to develop asphalt-based conductive mixtures. However, this method requires that the amount of conductive phase added exceeds the percolation threshold. In this case, it is basically impossible to achieve uniform dispersion of the conductive phase to form a complete conductive path; more seriously, the agglomerated conductive phase seriously damages the road performance of the asphalt mixture. Summary of the invention

[0004] The purpose of the present application is to provide a conductive aggregate and a preparation method thereof, an asphalt mixture and a preparation method and application thereof, aiming at least to solve the technical problem of agglomeration when the conductive phase is mixed with the asphalt matrix.

[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0006] In a first aspect, the present application provides a conductive aggregate, the conductive aggregate comprising: an aggregate matrix and a conductive film, the conductive film being coated on the surface of the aggregate matrix;

[0007] The conductive film comprises an adhesive and a carbon nanomaterial that forms a three-dimensional conductive network on the surface of the aggregate matrix;

[0008] The thickness of the conductive film is 20 μm-70 μm.

[0009] The conductive aggregate provided in the first aspect of the present application comprises: an aggregate matrix and a conductive film, wherein the conductive film is coated on the surface of the aggregate matrix; the components of the conductive film include an adhesive and a carbon nanomaterial that forms a three-dimensional conductive network on the surface of the aggregate matrix; the thickness of the conductive film is 20 μm-70 μm. The conductive film is coated on the surface of the aggregate matrix to form the conductive aggregate, which is then mixed with the asphalt matrix to obtain an asphalt mixture, which can effectively prevent the carbon nanomaterial from agglomerating when it is directly mixed with the asphalt matrix as a conductive phase while maintaining the physicochemical properties of the asphalt matrix. The thickness of the conductive film is 20 μm-70 μm. Within this thickness range, the particle size of the conductive aggregate obtained is not much different from that of the aggregate matrix, so that the mixing of the conductive aggregate obtained with the asphalt matrix does not affect the skeleton support and other functions of the asphalt matrix and the aggregate matrix after mixing. In addition, since the conductive aggregate contains carbon nanomaterials, which are not only good conductors of electricity but also good conductors of heat, the conductive aggregate has excellent microwave-induced heating effect, which can shorten the preheating temperature and time of the conductive aggregate when preparing asphalt mixture, greatly reduce energy consumption and improve construction efficiency.

[0010] As a possible implementation of the conductive aggregate of the present application, the carbon nanomaterial includes at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes. In this case, the aspect ratio of the multi-walled carbon nanotubes is generally 50-4000, and it is easy to disperse to form a dispersion; and the unit product cost is low, and it has high thermal and chemical stability.

[0011] As a possible implementation of the conductive aggregate of the present application, the adhesive includes at least one of polyacrylic acid and polyurethane. In this case, the conductive film formed by at least one of polyacrylic acid and polyurethane combined with carbon nanomaterials can be stably and evenly coated on the surface of the aggregate matrix and will not fall off due to external factors such as high temperature.

[0012] As a possible implementation of the conductive aggregate of the present application, the aggregate matrix includes at least one of granite, limestone, and glass. In this case, granite, limestone, and glass are all common materials with low acquisition costs.

[0013] In a second aspect, the present application provides a method for preparing a conductive aggregate, the preparation method comprising the following steps:

[0014] Mixing and dispersing the carbon nanomaterial dispersion and the adhesive solution to obtain a conductive polymer dispersion;

[0015] The conductive polymer dispersion is used to form a wet film layer on the surface of the aggregate matrix to obtain a wet material;

[0016] The wet material is dried to obtain a conductive aggregate with a conductive film coated on the surface of the aggregate matrix.

[0017] The second aspect of the present application provides a method for preparing conductive aggregate. The preparation method first prepares a conductive polymer dispersion, uses the conductive polymer dispersion to form a wet film layer on the surface of an aggregate matrix to obtain a wet material, and dries the wet material to obtain a conductive aggregate with a conductive film coated on the surface of the aggregate matrix. Among them, the conductive polymer dispersion is prepared so that the carbon nanomaterial dispersion and the adhesive solution are evenly mixed so as to uniformly coat the aggregate matrix subsequently; the conductive polymer dispersion and the aggregate matrix are made into a wet material; and the wet material is then dried to remove excess water and other solvents in the wet material. The conductive aggregate prepared by the preparation method has a conductive film uniformly coated on the surface of the aggregate matrix, which not only solves the problem of agglomeration caused by the carbon nanomaterial as a conductive phase directly mixed in the asphalt matrix, but also increases the conductivity of the asphalt matrix.

[0018] As a possible implementation of the method for preparing the conductive aggregate of the present application, the adhesive solution includes at least one of a polyacrylic acid solution and a polyurethane solution. In this case, at least one of the polyacrylic acid solution and the polyurethane solution is mixed with a carbon nanomaterial dispersion to form a conductive polymer dispersion, and the conductive polymer is uniformly deposited on the aggregate matrix to form a conductive film, which can be stably and uniformly coated on the surface of the aggregate matrix and will not fall off due to external factors such as high temperature.

[0019] As a possible implementation of the method for preparing the conductive aggregate of the present application, the mass fraction of the carbon nanomaterial in the carbon nanomaterial dispersion is 5%-8%. In this mass fraction range, the carbon nanomaterial dispersion is easily mixed with the adhesive solution to obtain the conductive polymer dispersion with excellent mechanical and electrical properties, and then prepare a conductive film with excellent performance.

[0020] As a possible implementation of the method for preparing the conductive aggregate of the present application, the mass fraction of the adhesive in the adhesive solution is 46%-50%. In this mass fraction range, the adhesive solution is easily mixed with the carbon nanomaterial dispersion to obtain the conductive polymer dispersion with excellent mechanical and electrical properties, and then prepare a conductive film with excellent performance.

[0021] As a possible implementation of the method for preparing the conductive aggregate of the present application, the volume resistivity of the conductive polymer dispersion is 0.10Ω·cm-0.15Ω·cm. In this volume resistivity range, the conductive aggregate is prepared to obtain a resistivity of 10Ω·cm-100Ω·cm.

[0022] As a possible implementation of the method for preparing the conductive aggregate of the present application, the volume ratio of the conductive polymer dispersion to the aggregate matrix is ​​(1.2-1.5):1.0. In this case, the aggregate matrix can be completely immersed in the conductive polymer dispersion, so that the conductive polymer (the conductive polymer includes carbon nanomaterials and adhesive) in the conductive polymer dispersion can be better wrapped on the surface of the aggregate matrix.

[0023] As a possible implementation of the method for preparing the conductive aggregate of the present application, the step of using the conductive polymer dispersion to form a wet film layer on the surface of the aggregate matrix includes: mixing the aggregate matrix and the conductive polymer dispersion for 5 minutes to 10 minutes and then sieving to obtain the wet material. In this case, the aggregate matrix and the conductive polymer dispersion can be preliminarily mixed, and the mixing method can be hand mixing; sieving is used to remove excess conductive polymer dispersion.

[0024] As a possible implementation of the method for preparing the conductive aggregate of the present application, the step of mixing and dispersing the carbon nano material dispersion and the adhesive solution includes: after mixing the carbon nano material dispersion and the adhesive solution, stirring and dispersing them at a speed of 2000r / min-3000r / min for 30min-40min to obtain the conductive polymer dispersion. In this case, stirring and dispersing the mixed carbon nano material dispersion and the adhesive solution can obtain a uniformly dispersed conductive polymer dispersion.

[0025] As a possible implementation of the method for preparing the conductive aggregate of the present application, the mass ratio of the carbon nanomaterial dispersion to the adhesive solution is (2.0-2.5):1.0. Within this mass ratio range, the carbon nanomaterial dispersion is easily mixed with the adhesive solution, thereby obtaining the conductive polymer dispersion having excellent mechanical and electrical properties, and further preparing a conductive film with excellent performance.

[0026] As a possible implementation of the method for preparing the conductive aggregate of the present application, the drying step includes: drying the wet material at 60°C-80°C for 48h-72h to obtain the conductive aggregate. In this case, during drying, the water and other solvents in the conductive polymer dispersion evaporate, and solid phase is deposited on the surface of the aggregate matrix to form a uniform and dense conductive film, and the drying environment can be selected from an oven.

[0027] In a third aspect, the present application provides an asphalt mixture, the components of which include an asphalt matrix, a conductive aggregate and a filler;

[0028] The conductive aggregate comprises an aggregate matrix and a conductive film coated on the surface of the aggregate matrix;

[0029] The mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate, and the mass of the filler is 1.0%-3.0% of the mass of the conductive aggregate.

[0030] The asphalt mixture provided in the third aspect of the present application includes an asphalt matrix, conductive aggregate and filler; the conductive aggregate includes an aggregate matrix and a conductive film coated on the surface of the aggregate matrix; the mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate, and the mass of the filler is 1.0%-3.0% of the mass of the conductive aggregate. The filler and the asphalt matrix are used to bond the conductive aggregate to improve the strength of the asphalt mixture; the conductive aggregate plays the role of skeleton support and conductivity in the asphalt mixture, and the conductive aggregate can also improve the self-repairing performance of the asphalt mixture and has the functions of electromagnetic shielding, pavement snow melting and ice removal, road weighing and traffic volume monitoring.

[0031] As a possible implementation of the asphalt mixture of the present application, the asphalt matrix includes PG-76 high-viscosity asphalt.

[0032] As a possible implementation of the asphalt mixture of the present application, the filler includes at least one of limestone powder, coal gangue powder, and ferrite powder. In this case, limestone powder, coal gangue powder, and ferrite powder are all commonly used fillers in asphalt mixtures, and the filler and the asphalt matrix are used to bond the conductive aggregate to improve the strength of the asphalt mixture.

[0033] As a possible implementation of the asphalt mixture of the present application, the target void ratio of the asphalt mixture is 22.5%-23.5%. In this case, the target void ratio can be regulated by the ratio of the asphalt matrix, the conductive aggregate and the filler in the asphalt mixture, and the asphalt mixture is a porous material with a target porosity of 22.5%-23.5%, and the porous material has a robust and abundant conductive path.

[0034] In a fourth aspect, the present application provides a method for preparing an asphalt mixture, the method comprising the following steps:

[0035] Obtaining raw material components of asphalt mixture, wherein the raw material components include conductive aggregate: asphalt matrix: filler in a mass ratio of 1: (0.03-0.05): (0.01-0.03);

[0036] Preheating the asphalt matrix and the conductive aggregate separately and then performing a first mixing process to obtain a first mixture;

[0037] The first mixture and filler are subjected to a second mixing treatment and then compacted to obtain the asphalt mixture.

[0038] The fourth aspect of the present application provides a method for preparing an asphalt mixture, wherein the method first obtains the raw materials and mass ratio of the asphalt mixture, preheats the asphalt matrix and the conductive aggregate respectively, and then mixes them, and then compacts them after mixing with the filler to obtain the asphalt mixture. The asphalt matrix and the conductive aggregate are preheated respectively to reduce the viscosity of the asphalt matrix and the conductive aggregate, making it easier to perform subsequent mixing treatment; and the conductive aggregate also has an excellent microwave-induced heating effect, which can shorten the preheating temperature and time of the conductive aggregate when preparing the asphalt mixture, greatly reducing energy consumption and improving construction efficiency. The method is simple in steps and easy to repeat.

[0039] As a possible implementation of the method for preparing asphalt mixture of the present application, the asphalt matrix is ​​preheated to a temperature of 165° C.-180° C. for a time of 2 h-3 h.

[0040] As a possible implementation of the method for preparing asphalt mixture of the present application, the temperature of preheating the conductive aggregate is 185° C.-195° C. and the time is 4 h-5 h.

[0041] As a possible implementation of the method for preparing asphalt mixture of the present application, the temperature of the first mixing treatment is 170°C-175°C.

[0042] As a possible implementation of the method for preparing asphalt mixture of the present application, the temperature of the second mixing treatment is 170°C-175°C.

[0043] As a possible implementation of the method for preparing asphalt mixture in the present application, the compaction temperature is 155°C-160°C.

[0044] As a possible implementation of the method for preparing asphalt mixture in the present application, the number of compaction is more than 50 times.

[0045] As a possible implementation of the method for preparing asphalt mixture in the present application, the compaction includes double-sided compaction.

[0046] As a possible implementation of the method for preparing asphalt mixture of the present application, the asphalt mixture is a continuously open-graded asphalt mixture.

[0047] In the fifth aspect, the present application provides an asphalt mixture described in the third aspect of the present application or an asphalt mixture prepared by the method described in the fourth aspect of the present application, and its application in road self-repair performance, electromagnetic shielding, road snow melting and ice removal, road weighing, and traffic volume monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 Schematic diagram of the process for preparing the conductive aggregate in the embodiment of the present application;

[0050] Figure 2 This is a schematic diagram of the process for preparing asphalt mixture in an embodiment of the present application;

[0051] Figure 3 The appearance and scanning electron microscope comparison of the aggregate matrix and the conductive aggregate in the embodiment of the present application (upper row: aggregate matrix; lower row: conductive aggregate);

[0052] Figure 4 Schematic diagram of heat source and heat propagation of asphalt mixture prepared in the embodiment of the present application and traditional conductive asphalt mixture during induction heating;

[0053] Figure 5 Schematic diagram comparing the induced heating test results of the asphalt mixture prepared in the embodiment of the present invention, ordinary asphalt mixture and traditional conductive asphalt mixture (wherein, the first row: ordinary asphalt mixture; the second row: traditional conductive asphalt mixture; the third row: conductive aggregate asphalt mixture of the present invention; the left column: at room temperature; the right column: microwave heating for 180s). DETAILED DESCRIPTION

[0054] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0055] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0056] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0057] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0058] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0059] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0060] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0061] In the term “PA-13”, PA means permeable asphalt concrete and 13 means the maximum aggregate size is 13 mm.

[0062] In the term "PG-76", PG stands for Peformance Grade, which indicates road performance, and 76 stands for operating temperature.

[0063] As the conductive phase, metal waste residues such as steel / iron slag (which has conductive properties) can be used to replace natural aggregates to make "conductive aggregate type" smart asphalt mixtures. Under induced heating, the "conductive aggregate type" smart asphalt mixture system has more uniform heat generation and heat transfer, and higher self-healing and snow melting and deicing efficiency.

[0064] However, the sources of metal waste slag are complex and the quality is not stable. Taking steel slag as an example, its free calcium oxide content is relatively high, and there are safety hazards such as unstable road performance and volume stability; the density of steel slag is 20-30% higher than that of natural aggregate (which means high freight costs), the porosity is high (which means high oil absorption and increased asphalt usage) and the adhesion with asphalt is poor. More importantly, the particle size distribution of steel slag is uneven, and it is not suitable to design the composition of mineral mixture alone. At the same time, in order to take into account the cost and performance of the mixture, steel slag is usually used to partially replace natural aggregate to prepare conductive asphalt mixture in actual use, which means that a good three-dimensional conductive skeleton structure cannot be formed inside the mixture. Based on this, the embodiments of the present application provide a conductive aggregate and a preparation method thereof, an asphalt mixture and a preparation method and application thereof. Conductive aggregate is a conductive film having a three-dimensional conductive network coated on the surface of the aggregate matrix. The introduction of the conductive film can effectively solve the agglomeration phenomenon of asphalt mixture.

[0065] The specific scheme includes: the first aspect of the embodiment of the present application provides a conductive aggregate, the conductive aggregate includes: an aggregate matrix and a conductive film, the conductive film is coated on the surface of the aggregate matrix;

[0066] The conductive film comprises an adhesive and a carbon nanomaterial that forms a three-dimensional conductive network on the surface of an aggregate matrix;

[0067] The thickness of the conductive film is 20 μm-70 μm.

[0068] The conductive aggregate provided in the first aspect of the embodiment of the present application includes: an aggregate matrix and a conductive film, wherein the conductive film is coated on the surface of the aggregate matrix; the components of the conductive film include an adhesive and a carbon nanomaterial that forms a three-dimensional conductive network on the surface of the aggregate matrix; the thickness of the conductive film is 20μm-70μm. Among them, the conductive film is coated on the surface of the aggregate matrix to form a conductive aggregate, which is then mixed with an asphalt matrix to obtain an asphalt mixture, which can effectively prevent the carbon nanomaterial from agglomerating when it is directly mixed with the asphalt matrix as a conductive phase while maintaining the physicochemical properties of the asphalt matrix. The thickness of the conductive film is 20μm-70μm. Within this thickness range, the particle size of the conductive aggregate obtained is not much different from that of the aggregate matrix, so that the mixing of the conductive aggregate obtained with the asphalt matrix does not affect the skeleton support and other functions of the asphalt matrix and the aggregate matrix after mixing. In addition, since the conductive aggregate contains carbon nanomaterials, which are not only good conductors of electricity but also good conductors of heat, the conductive aggregate has excellent microwave induced heating effect, which can shorten the preheating temperature and time of the conductive aggregate when preparing asphalt mixture, greatly reduce energy consumption and improve construction efficiency. Exemplarily, the thickness of the conductive film can be 5nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm and other specific situations.

[0069] As a possible implementation of the conductive aggregate in the embodiment of the present application, the resistivity of the conductive aggregate is 10Ω·cm-100Ω·cm. In this case, the resistivity of the conductive aggregate is determined by the mixing ratio of the carbon nanomaterial and the adhesive, and the lower resistivity reflects that the conductive aggregate has a better conductive function. Exemplarily, the resistivity of the conductive aggregate can be 10Ω·cm, 20Ω·cm, 30Ω·cm, 40Ω·cm, 50Ω·cm, 60Ω·cm, 70Ω·cm, 80Ω·cm, 90Ω·cm, 100Ω·cm and other specific situations.

[0070] As a possible implementation of the conductive aggregate in the embodiment of the present application, the carbon nanomaterial includes at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes. In this case, the aspect ratio of the multi-walled carbon nanotubes is generally 50-4000, and it is easy to disperse to form a dispersion; and the unit product cost is low, and it has high thermal and chemical stability; in addition, the multi-walled carbon nanotubes are one-dimensional carbon nanotubes, which are easy to disperse to form a dispersion and easy to overlap with the aggregate matrix.

[0071] In some embodiments, the density of the multi-walled carbon nanotubes is 2.0 g / cm 3 -2.5g / cm 3 , specific surface area is 250m2 / g-300m 2 / g, and the conductivity is 150s / cm-250s / cm. In this case, the multi-walled carbon nanotubes can increase the specific surface area of ​​the aggregate matrix and increase the conductivity of the aggregate matrix.

[0072] In some embodiments, the multi-walled carbon nanotubes are prepared by using a vapor deposition (CVD) method.

[0073] As a possible implementation of the conductive aggregate in the embodiment of the present application, the adhesive includes at least one of polyacrylic acid and polyurethane. In this case, the conductive film formed by at least one of polyacrylic acid and polyurethane combined with carbon nanomaterials can be stably and evenly coated on the surface of the aggregate matrix and will not fall off due to external factors such as high temperature.

[0074] As a possible implementation of the conductive aggregate in the embodiment of the present application, the aggregate matrix includes at least one of granite, limestone, and glass. In this case, granite, limestone, and glass are all common materials with low acquisition costs.

[0075] As a possible implementation of the conductive aggregate in the embodiment of the present application, the particle size of the conductive aggregate is not greater than 14 mm. Within this particle size range of the conductive aggregate, the conductive aggregate is mixed with the asphalt matrix and the filler to prepare an asphalt mixture with a grading of PA-13. Exemplarily, the particle size of the conductive aggregate can be 14 mm, 13.8 mm, 13.6 mm, 13.4 mm, 13.2 mm, 13 mm, and other specific situations.

[0076] The second aspect of the present application provides a method for preparing a conductive aggregate, as shown in the attached Figure 1 As shown, the preparation method comprises the following steps:

[0077] S10. Mix and disperse the carbon nanomaterial dispersion and the adhesive solution to obtain a conductive polymer dispersion.

[0078] S20. A conductive polymer dispersion is used to form a wet film layer on the surface of the aggregate matrix to obtain a wet material.

[0079] S30. Drying the wet material to obtain a conductive aggregate having a conductive film coated on the surface of the aggregate matrix.

[0080] The second aspect of the embodiment of the present application provides a method for preparing conductive aggregate. The preparation method first prepares a conductive polymer dispersion, uses the conductive polymer dispersion to form a wet film layer on the surface of the aggregate matrix to obtain a wet material, and dries the wet material to obtain a conductive aggregate with a conductive film coated on the surface of the aggregate matrix. Among them, the conductive polymer dispersion is prepared to mix the carbon nanomaterial dispersion and the adhesive solution evenly so as to uniformly coat the aggregate matrix subsequently; the conductive polymer dispersion and the aggregate matrix are made into a wet material; and the wet material is then dried to remove excess water and other solvents in the wet material. The conductive aggregate prepared by the preparation method has a conductive film uniformly deposited on the surface of the aggregate matrix, which not only solves the problem of agglomeration caused by the carbon nanomaterial as a conductive phase directly mixed in the asphalt matrix, but also increases the conductivity of the asphalt matrix.

[0081] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, preparing the carbon nanomaterial dispersion includes the following steps:

[0082] In an ice bath, the carbon nanomaterial and the sodium dodecyl sulfate solution are mixed and ultrasonicated to obtain a carbon nanomaterial dispersion.

[0083] In some embodiments, the carbon nanomaterial and the sodium dodecyl sulfate solution are mixed and ultrasonicated with an ultrasonic power of 70W-80W and an ultrasonic time of 450min-600min. Under this ultrasonic power and time range, the carbon nanomaterial can be uniformly dispersed in the sodium dodecyl sulfate solution to obtain a carbon nanomaterial dispersion. Exemplarily, the ultrasonic power can be 70W, 71W, 72W, 73W, 74W, 75W, 76W, 77W, 78W, 79W, 80W and other specific situations; the ultrasonic time can be 450min, 460min, 470min, 480min, 490min, 500min, 510min, 520min, 530min, 540min, 550min, 560min, 570min, 580min, 590min, 600min and other specific situations.

[0084] In some embodiments, the mass fraction of sodium dodecyl sulfate in the sodium dodecyl sulfate solution is 5%-10%. Within this mass fraction range, the carbon nanomaterial can be uniformly dispersed in the sodium dodecyl sulfate solution by ultrasound to obtain a carbon nanomaterial dispersion. Exemplarily, the mass fraction of sodium dodecyl sulfate can be 5%, 6%, 7%, 8%, 9%, 10%, and other specific situations.

[0085] In some embodiments, the preparation method of the sodium dodecyl sulfate solution includes: mixing sodium dodecyl sulfate with water and stirring the mixture with a magnetic stirrer for more than 24 hours to obtain the sodium dodecyl sulfate solution.

[0086] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, the adhesive solution includes at least one of a polyacrylic acid solution and a polyurethane solution. In this case, at least one of the polyacrylic acid solution and the polyurethane solution is mixed with a carbon nanomaterial dispersion to form a conductive polymer dispersion, and the conductive film prepared by uniformly depositing the conductive polymer on the aggregate matrix can be stably and uniformly coated on the surface of the aggregate matrix and will not fall off due to external factors such as high temperature.

[0087] In some embodiments, the molecular weight of polypropylene in the polyacrylic acid solution is 500-5000, the pH value is 2-4, and the dissociation constant is 4×10 -5 -6×10 -5 .

[0088] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, the mass ratio of the carbon nanomaterial dispersion and the adhesive solution is (2.0-2.5):1.0. In this mass ratio range, the carbon nanomaterial dispersion is easily mixed with the carboxylic acid polymer solution to obtain a conductive polymer dispersion with excellent mechanical and electrical properties, thereby preparing a conductive film with excellent performance. Exemplarily, the mass ratio can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1 and other specific situations.

[0089] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, the step of mixing and dispersing the carbon nanomaterial dispersion and the adhesive solution includes:

[0090] After the carbon nanomaterial dispersion and the adhesive solution are mixed, they are stirred and dispersed at a speed of 2000r / min-3000r / min for 30min-40min to obtain a conductive polymer dispersion. In this case, the mixed carbon nanomaterial dispersion and the adhesive solution are stirred and dispersed to obtain a uniformly dispersed conductive polymer dispersion. Under this speed and time range, a uniformly dispersed conductive polymer dispersion is obtained. Exemplarily, the speed can be 2000r / min, 2500r / min, 3000r / min and other specific situations; the time can be 30min, 32min, 34min, 36min, 38min, 40min and other specific situations.

[0091] In some embodiments, the mixing time of the carbon nanomaterial dispersion and the adhesive solution is 1 min to 1.5 min. Under this mixing time, a preliminarily mixed system can be obtained, and the mixing method can be manual stirring and mixing.

[0092] In some specific embodiments, a high-speed shearing machine is used to stir and disperse the mixed carbon nanomaterial dispersion and adhesive solution: the high-speed shearing machine is first sheared at a speed of 2000 r / min for 10 minutes, and then sheared at a speed of 3000 r / min for 20 minutes. In this case, the conductive polymer dispersion obtained by stirring is evenly dispersed.

[0093] In other specific embodiments, a high-speed shearing machine is used to stir and disperse the mixed carbon nanomaterial dispersion and adhesive solution: the high-speed shearing machine is cycled at a speed of 2000 r / min and 3000 r / min for 30 minutes. In this case, the conductive polymer dispersion obtained by stirring is more uniformly dispersed.

[0094] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, the mass fraction of the carbon nanomaterial in the carbon nanomaterial dispersion is 5%-8%; the mass fraction of the adhesive in the adhesive solution is 46%-50%. In this mass fraction range, the carbon nanomaterial dispersion is easily mixed with the carboxylic acid polymer solution, thereby obtaining a conductive polymer dispersion with excellent mechanical and electrical properties, and then preparing a conductive film with excellent performance.

[0095] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S10, the volume resistivity of the conductive polymer dispersion is 0.10Ω·cm-0.15Ω·cm. Under this volume resistivity range, the conductive aggregate is prepared, and the resistivity of the obtained conductive aggregate is 10Ω·cm-100Ω·cm.

[0096] As a possible implementation of the method for preparing conductive aggregate in the embodiment of the present application, in the above step S20, the aggregate matrix is ​​screened and the aggregate matrix with a particle size not greater than 14 mm is selected before mixing with the conductive polymer dispersion. Under this particle size range of the aggregate matrix, the conductive aggregate is made. Since the thickness of the conductive film in the conductive aggregate is micron-level, the particle size of the aggregate matrix is ​​slightly affected. Therefore, the prepared conductive aggregate is mixed with the asphalt matrix and filler to prepare an asphalt mixture with a grading of PA-13. Exemplarily, the particle size of the aggregate matrix can be 14 mm, 13.8 mm, 13.6 mm, 13.4 mm, 13.2 mm, 13 mm, and other specific situations.

[0097] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S20, the step of using the conductive polymer dispersion to form a wet film layer on the surface of the aggregate matrix includes: mixing the aggregate matrix and the conductive polymer dispersion for 5min-10min and then sieving to obtain a wet material. In this case, the aggregate matrix and the conductive polymer dispersion can be preliminarily mixed, and the mixing method can be hand mixing; sieving is used to remove excess conductive polymer dispersion. Exemplarily, the mixing time can be 5min, 6min, 7min, 8min, 9min, 10min, etc.

[0098] As a possible implementation of the method for preparing the conductive aggregate in the embodiment of the present application, in the above step S20, the volume ratio of the conductive polymer dispersion to the aggregate matrix is ​​(1.2-1.5):1.0. In this case, the aggregate matrix can be completely immersed in the conductive polymer dispersion, so that the conductive polymer (the conductive polymer includes carbon nanomaterials and adhesives) in the conductive polymer dispersion can be better wrapped on the surface of the aggregate matrix. Exemplarily, the volume ratio can be 1.0:1.2, 1.0:1.3, 1.0:1.4, 1.0:1.5 and other specific situations.

[0099] As a possible implementation of the method for preparing conductive aggregate in the embodiment of the present application, in the above step S30, the step of drying treatment includes: drying the wet material at 60°C-80°C for 48h-72h to obtain conductive aggregate. In this case, during drying, the water and other solvents in the conductive polymer dispersion evaporate, and solid phase is deposited on the surface of the aggregate matrix to form a uniform and dense conductive film, and the drying environment can be selected from an oven. Exemplarily, the drying temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, 60°C-65°C, 65°C-70°C, 70°C-75°C, 75°C-80°C, 60°C-70°C, 65°C-75°C, 70°C-80°C and other specific situations; the drying time can be 48h, 50h, 52h, 54h, 56h, 58h, 60h, 62h, 64h, 66h, 68h, 70h, 72h and other specific situations.

[0100] A third aspect of the present application provides an asphalt mixture, the components of the asphalt mixture including an asphalt matrix, a conductive aggregate and a filler;

[0101] The conductive aggregate comprises an aggregate matrix and a conductive film coated on the surface of the aggregate matrix;

[0102] The mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate, and the mass of the filler is 1.0%-3.0% of the mass of the conductive aggregate.

[0103] The asphalt mixture provided in the third aspect of the embodiment of the present application includes an asphalt matrix, conductive aggregate and filler; the conductive aggregate includes an aggregate matrix and a conductive film coated on the surface of the aggregate matrix; the mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate, and the mass of the filler is 1.0%-3.0% of the mass of the conductive aggregate. Among them, the filler and the asphalt matrix are used to bond the conductive aggregate to improve the strength of the asphalt mixture; the conductive aggregate plays the role of skeleton support and conductivity in the asphalt mixture, and the conductive aggregate can improve the self-repairing performance of the asphalt mixture and has the functions of electromagnetic shielding, pavement snow melting and ice removal, road weighing, and traffic volume monitoring. In addition, in asphalt mixture, the mass of asphalt matrix is ​​selected to be 3.0%-5.0% of the mass of conductive aggregate. Under this range, the self-repairing performance and electromagnetic shielding of asphalt mixture are improved while maintaining the physical and chemical properties of asphalt matrix itself; conductive aggregate will not agglomerate when mixed with asphalt matrix as conductive phase; the mass of filler is selected to be 1.0%-3.0% of the mass of conductive aggregate. Under this range, the added filler can combine with asphalt matrix to improve the strength of asphalt mixture without affecting the physical and chemical properties of conductive aggregate. Asphalt mixture has a robust and rich conductive path. Exemplarily, the mass of the asphalt matrix can be 3.0%, 3.1%, 3.3%, 3.5%, 3.7%, 3.9%, 4.0%, 4.1%, 4.3%, 4.5%, 4.7%, 4.9%, 5.0% of the mass of the conductive aggregate; the mass of the filler can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0% of the mass of the conductive aggregate.

[0104] As a possible implementation of the asphalt mixture in the embodiment of the present application, the asphalt matrix includes PG-76 high-viscosity asphalt.

[0105] As a possible implementation of the asphalt mixture in the embodiment of the present application, the filler includes at least one of limestone powder, coal gangue powder, and ferrite powder. In this case, limestone powder, coal gangue powder, and ferrite powder are all commonly used fillers in asphalt mixtures, and the filler and the asphalt matrix are used to bond the conductive aggregate to improve the strength of the asphalt mixture.

[0106] As a possible implementation of the asphalt mixture in the embodiment of the present application, the target void ratio of the asphalt mixture is 22.5%-23.5%. In this case, the target void ratio can be regulated by the ratio of the asphalt matrix, the conductive aggregate and the filler in the asphalt mixture, and the asphalt mixture is a porous material with a target porosity of 22.5%-23.5%, and the porous material has a robust and rich conductive path.

[0107] As a possible implementation of the asphalt mixture in the embodiment of the present application, the asphalt-to-stone ratio of the asphalt mixture is the mass ratio of the asphalt matrix to the conductive aggregate, that is, 0.03-0.05:1 (that is, the mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate). Within this asphalt-to-stone ratio range, the asphalt mixture has high self-repair, electromagnetic shielding, pavement snow melting and deicing, road weighing, and traffic volume monitoring performance.

[0108] A fourth aspect of the present application provides a method for preparing an asphalt mixture, as shown in the following Figure 2 As shown, the method comprises the following steps:

[0109] X10. Obtain raw material components of asphalt mixture, the raw material components including conductive aggregate: asphalt matrix: filler in a mass ratio of 1: (0.03-0.05): (0.01-0.03).

[0110] X20. After preheating the asphalt matrix and the conductive aggregate respectively, perform a first mixing process to obtain a first mixture.

[0111] X30. Perform a second mixing process on the first mixture and the filler and then compact them to obtain an asphalt mixture.

[0112] The fourth aspect of the present application provides a method for preparing an asphalt mixture, which first obtains the raw materials and mass ratio of the asphalt mixture, preheats the asphalt matrix and the conductive aggregate respectively, and then mixes them, and then compacts them after mixing with the filler to obtain the asphalt mixture. The asphalt matrix and the conductive aggregate are preheated separately to reduce the viscosity of the asphalt matrix and the conductive aggregate, making the subsequent mixing process easier; and the conductive aggregate also has an excellent microwave-induced heating effect, which can shorten the preheating temperature and time of the conductive aggregate when preparing the asphalt mixture, greatly reducing energy consumption and improving construction efficiency. The method has simple steps and is easy to repeat.

[0113] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X20, the temperature of preheating the asphalt base is 165°C-180°C, and the time is 2h-3h. For example, the preheating temperature can be 165°C, 170°C, 180°C, etc.; the preheating time can be 2h, 2.5h, 3h, etc.

[0114] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X20, the temperature of preheating the conductive aggregate is 185°C-195°C, and the time is 4h-5h. Exemplarily, the preheating temperature can be 185°C, 190°C, 195°C, etc.; the preheating time can be 4h, 4.5h, 5h, etc.

[0115] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X20, the temperature of the first mixing treatment is 170° C.-175° C. Exemplarily, the temperature of the first mixing treatment can be 170° C., 171° C., 172° C., 173° C., 174° C., 175° C., and other specific situations.

[0116] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X30, the temperature of the second mixing process is 170° C.-175° C. Exemplarily, the temperature of the first mixing process can be 170° C., 171° C., 172° C., 173° C., 174° C., 175° C., etc.

[0117] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X30, the compaction temperature is 155°C-160°C.

[0118] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X30, the number of compaction times is more than 50 times.

[0119] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above-mentioned step X30, compaction includes double-sided compaction.

[0120] As a possible implementation of the method for preparing asphalt mixture in the embodiment of the present application, in the above step X30, the asphalt mixture is a continuously open-graded asphalt mixture, preferably PA-13, that is, an open-graded asphalt mixture with a maximum aggregate particle size of 13.2 mm.

[0121] In some embodiments, the method for preparing the asphalt mixture is prepared according to the method in the Chinese standard JTG / T3350-03-2020. In this case, the mass of the selected asphalt matrix is ​​3.9% of the mass of the conductive aggregate, the target void ratio is 22.5%-23.5%, the asphalt matrix is ​​PG-76 high-viscosity asphalt, and the asphalt mixture prepared is an open-graded asphalt mixture with a maximum aggregate particle size of 13.2 mm.

[0122] The fifth aspect of the embodiment of the present application provides an asphalt mixture provided in the third aspect of the embodiment of the present application or an asphalt mixture prepared by the method provided in the fourth aspect of the embodiment of the present application, and its application in road self-repair performance, electromagnetic shielding, road snow melting and de-icing, road weighing, and traffic volume monitoring.

[0123] The following describes the invention in conjunction with specific embodiments.

[0124] Example 1

[0125] A method for preparing an asphalt mixture, the method comprising the following steps:

[0126] (1) Preparation of a carbon nanomaterial dispersion: In an ice bath, carbon nanotubes (conductivity of 200 s / cm) and a sodium dodecyl sulfate solution (wherein the mass fraction of sodium dodecyl sulfate is 6%) are mixed and ultrasonicated at a power of 70-80 W for 500 min to obtain a carbon nanomaterial dispersion. The mass fraction of carbon nanotubes in the prepared carbon nanomaterial dispersion is 5%.

[0127] (2) Preparation of conductive polymer dispersion: The carbon nanomaterial dispersion and the polyacrylic acid solution were mixed in a mass ratio of 2:1, first mixed by hand for 1 minute, then sheared at 2000 r / min for 10 minutes using a high-speed shearing machine, and then sheared at 3000 r / min for 20 minutes (or: cycled at 2000 r / min and 3000 r / min for 30 minutes) to obtain a uniformly dispersed conductive polymer dispersion. The mass fraction of polyacrylic acid in the polyacrylic acid solution is 46%.

[0128] (3) Preparation of conductive aggregate: The conductive polymer dispersion and the screened aggregate matrix were mixed at a volume ratio of 1.2:1 and hand-mixed for 10 minutes to obtain a wet material with the conductive polymer uniformly coated on the surface of the aggregate matrix. The wet material was placed in an oven and dried at 80°C for 72 hours to obtain a conductive aggregate with a conductive film uniformly coated on the surface.

[0129] (4) Prepare asphalt mixture according to the method in standard JTG / T 3350-03-2020:

[0130] ① The asphalt matrix is ​​selected from PG-76 high-viscosity asphalt, the filler is selected from limestone powder, and the conductive aggregate is the conductive aggregate prepared in (3).

[0131] ② Prepare the raw materials of asphalt mixture with the mass of PG-76 high viscosity asphalt being 3.9% of the mass of conductive aggregate and the mass of limestone powder being 1.5% of the mass of conductive aggregate.

[0132] ③ Preheat PG-76 high viscosity asphalt at 170℃ for 2h; preheat the conductive aggregate at 190℃ for 4h.

[0133] ④ At a temperature of 170-175° C., the preheated PG-76 high-viscosity asphalt, conductive aggregate and limestone powder are mixed to obtain a mixture.

[0134] ⑤ At a temperature of 155-160°C, compact the mixture on both sides for 50 times to obtain an asphalt mixture.

[0135] Example 2

[0136] A method for preparing an asphalt mixture, the steps of the method are substantially the same as those of Example 1, except that: the mass fraction of the carbon nanomaterial is 8%;

[0137] The mass fraction of polyacrylic acid in the polyacrylic acid solution is 50%.

[0138] Example 3

[0139] A method for preparing an asphalt mixture, the steps of the method are substantially the same as those of Example 1, except that: the mass fraction of the polyacrylic acid in the polyacrylic acid solution is 48%;

[0140] The mass ratio of the carbon nanomaterial dispersion to the polyacrylic acid solution is 2.5:1;

[0141] When preparing the conductive aggregate in (3), the conductive polymer dispersion and the screened aggregate matrix were mixed in a volume ratio of 1:1.2 and mixed by hand for 5 minutes.

[0142] Example 4

[0143] A method for preparing an asphalt mixture, the steps of the method are substantially the same as those of Example 1, except that: the mass fraction of the polyacrylic acid in the polyacrylic acid solution is 48%;

[0144] The mass ratio of the carbon nanomaterial dispersion to the polyacrylic acid solution is 2.5:1;

[0145] When preparing the conductive aggregate in (3), the wet material was placed in an oven and dried at 70°C for 48 hours.

[0146] Comparative Example 1

[0147] A method for preparing an asphalt mixture, the method comprising the following steps:

[0148] (1) Preparation of a carbon nanomaterial dispersion: In an ice bath, carbon nanotubes (conductivity of 200 s / cm) and a sodium dodecyl sulfate solution (wherein the mass fraction of sodium dodecyl sulfate is 6%) are mixed and ultrasonicated at a power of 70-80 W for 500 min to obtain a carbon nanomaterial dispersion. The mass fraction of carbon nanotubes in the prepared carbon nanomaterial dispersion is 5%.

[0149] (2) Preparation of conductive polymer powder: The carbon nanomaterial dispersion and the polyacrylic acid solution are mixed in a mass ratio of 2:1, first mixed by hand for 1 minute, then sheared at 2000 r / min for 10 minutes using a high-speed shearing machine, and then sheared at 3000 r / min for 20 minutes (or: cycled at 2000 r / min and 3000 r / min for 30 minutes) to obtain a uniformly dispersed conductive polymer dispersion; then the conductive polymer dispersion is dried and ground into powder to obtain a powdered conductive polymer. The mass fraction of polyacrylic acid in the polyacrylic acid solution is 46%.

[0150] (3) Prepare asphalt mixture according to the method in standard JTG / T 3350-03-2020:

[0151] ① The asphalt is selected from PG-76 high viscosity asphalt, the filler is selected from limestone powder, the conductive phase is selected from the powdered conductive polymer prepared in (2), and then the natural aggregate (aggregate matrix) is selected.

[0152] ② Prepare the raw materials for asphalt mixture by taking the mass of PG-76 high viscosity asphalt as 3.9% of the mass of aggregate matrix and the mass of limestone powder as 1.5% of the mass of aggregate matrix.

[0153] ③ Preheat the PG-76 high-viscosity asphalt at 170°C for 2 hours; preheat the aggregate matrix at 190°C for 4 hours.

[0154] ④ At a temperature of 170-175°C, the preheated PG-76 high-viscosity asphalt and aggregate matrix are mixed with limestone powder to obtain a first mixture.

[0155] ⑤ At a temperature of 155-160°C, compact the first mixture on both sides for 50 times to obtain an asphalt mixture.

[0156] Comparative Example 2

[0157] A method for preparing an asphalt mixture, the steps of the method are basically the same as those of comparative example 1, except that: comparative example 2 does not prepare conductive polymer powder; the raw materials for preparing the asphalt mixture are asphalt matrix, aggregate matrix and limestone powder, and do not contain conductive polymer powder.

[0158] In order to verify the progress of the embodiments of the present application, the conductive aggregates prepared in Examples 1-4 and the aggregate matrix involved in Comparative Examples 1-2 were subjected to a 24h water absorption test, and the conductive aggregates and aggregate matrix were compared in appearance and scanning electron microscopy; the asphalt mixtures prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to a Marshall test and a microwave induced heating test. The experimental results of the water absorption test and the Marshall test are shown in Table 1 below, and the appearance and scanning electron microscopy comparison of the conductive aggregate and the aggregate matrix are shown in Table 1 below. Figure 3As shown in the attached figure, the heat source and heat propagation in the induced heating experiment are shown in the attached figure. Figure 4 As shown in the figure, the induced heating test results are compared with the attached Figure 5 shown.

[0159] Table 1

[0160]

[0161] From Table 1 above and the attached Figure 3-5 It can be seen that:

[0162] 1) In Examples 1-4, conductive aggregates were added, while in Comparative Examples 1-2, unmodified aggregate matrix was added. Compared with the aggregate matrix, the water absorption rate of the conductive aggregates was reduced by about 20%, which is beneficial to improving the conductive stability of the asphalt mixture in a humid environment. The reduction in water absorption is mainly because the conductive film formed after the conductive polymer is dried is mainly carbon nanomaterials (carbon nanotubes), which are surface inert and hydrophobic materials.

[0163] 2) Compared with the control example, the pull-out strength of the asphalt mixture prepared in the example of the present application and the asphalt stripping rate in the boiling water test are not much different, indicating that the conductive aggregate made by depositing a conductive film on the aggregate matrix has almost no effect on the adhesion between the asphalt and the aggregate matrix.

[0164] 3) Compared with the control example, the Marshall strength and indirect tensile strength of the asphalt mixture prepared using conductive aggregate are not much different (almost equal), that is, the conductive aggregate has almost no negative impact on the mechanical strength of the asphalt mixture, and the asphalt mixture prepared in the embodiment of the present application still has good durability.

[0165] 4) Compared with Comparative Example 2, under the same preparation method and the same amount of conductive phase, the resistivity of the asphalt mixture prepared in Comparative Example 1 is reduced by 6 orders of magnitude compared with the resistivity of the asphalt mixture prepared in Comparative Example 2, while the resistivity of the asphalt mixture prepared in Examples 1-4 of the present application is greatly reduced by 8 orders of magnitude compared with the resistivity of the asphalt mixture prepared in Comparative Example 2. It can be seen that the resistivity of the asphalt mixture prepared in Examples 1-4 of the present application is greatly reduced, has excellent conductivity, and can be applied to electromagnetic shielding and other fields.

[0166] 5) Compared with Comparative Example 2, under the same preparation method and the same amount of conductive phase, the surface temperature of the asphalt mixture prepared in Comparative Example 1 rises to about 95°C, while the surface temperature of the asphalt mixture prepared in Examples 1-4 of the present application reaches about 150°C, which is nearly 110% higher than that in Comparative Example 1. It can be seen that the asphalt mixtures prepared in Examples 1-4 of the present application have excellent thermal conductivity. The preheating temperature and time of the conductive aggregate can be shortened, which greatly reduces energy consumption and improves construction efficiency.

[0167] 6) It can be seen from Examples 1-3 that the optimal mass fraction of the carbon nanomaterial dispersion is 5%, and the optimal mass fraction of the polyacrylic acid solution is 48%.

[0168] In addition, the attached Figure 3 It can be seen that in the conductive aggregate prepared in the embodiment of the present application, the surface of the aggregate matrix has a conductive film and has good conductivity.

[0169] By the attached Figure 4 It can be seen that the conductive aggregate prepared in the embodiment of the present application has better heat transfer performance and can transfer heat evenly.

[0170] By the attached Figure 5 It can be seen that the thermal transfer performance of the asphalt mixture prepared in the embodiments of the present application is higher than that of ordinary asphalt mixture and traditional conductive asphalt mixture.

[0171] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A conductive aggregate, characterized in that: The conductive aggregate comprises: an aggregate matrix and a conductive film, wherein the conductive film is coated on the surface of the aggregate matrix; The conductive film comprises an adhesive and a carbon nanomaterial that forms a three-dimensional conductive network on the surface of the aggregate matrix; The thickness of the conductive film is 20 μm-70 μm.

2. The conductive aggregate according to claim 1, characterized in that: The carbon nanomaterial includes at least one of multi-walled carbon nanotubes and single-walled carbon nanotubes; And / or, the adhesive includes at least one of polyacrylic acid and polyurethane; And / or, the aggregate matrix includes at least one of granite, limestone, and glass; And / or, the mass ratio of the aggregate matrix to the conductive film is (200-700):1; And / or, in the conductive film, the mass ratio of the carbon nanomaterial to the adhesive is (2.0-2.5):1.

0.

3. A method for preparing a conductive aggregate, characterized in that: The preparation method comprises the following steps: Mixing and dispersing the carbon nanomaterial dispersion and the adhesive solution to obtain a conductive polymer dispersion; The conductive polymer dispersion is used to form a wet film layer on the surface of the aggregate matrix to obtain a wet material; The wet material is dried to obtain a conductive aggregate with a conductive film coated on the surface of the aggregate matrix.

4. The preparation method according to claim 3, characterized in that: The adhesive solution includes at least one of a polyacrylic acid solution and a polyurethane solution; And / or, the mass fraction of the carbon nanomaterial in the carbon nanomaterial dispersion is 5%-8%; And / or, the mass fraction of the adhesive in the adhesive solution is 46%-50%; and / or, the volume resistivity of the conductive polymer dispersion is 0.10Ω·cm-0.15Ω·cm; and / or, the volume ratio of the conductive polymer dispersion to the aggregate matrix is ​​(1.2-1.5):1.0; And / or, the step of using the conductive polymer dispersion to form a wet film layer on the surface of the aggregate matrix includes: mixing the aggregate matrix and the conductive polymer dispersion for 5 minutes to 10 minutes and then sieving to obtain the wet material.

5. The preparation method according to claim 3 or 4, characterized in that: The step of mixing and dispersing the carbon nano material dispersion and the adhesive solution comprises: mixing the carbon nano material dispersion and the adhesive solution, and then stirring and dispersing them at a rotation speed of 2000 r / min-3000 r / min for 30 min-40 min to obtain the conductive polymer dispersion; And / or, the mass ratio of the carbon nanomaterial dispersion to the adhesive solution is (2.0-2.5):1.0; And / or, the drying step includes: drying the wet material at 60° C.-80° C. for 48 h-72 h to obtain the conductive aggregate.

6. An asphalt mixture, characterized in that: The components of the asphalt mixture include an asphalt matrix, conductive aggregate and filler; the conductive aggregate includes an aggregate matrix and a conductive film coated on the surface of the aggregate matrix; The mass of the asphalt matrix is ​​3.0%-5.0% of the mass of the conductive aggregate, and the mass of the filler is 1.0%-3.0% of the mass of the conductive aggregate.

7. The asphalt mixture according to claim 6, characterized in that: The asphalt matrix includes PG-76 high-viscosity asphalt; And / or, the filler includes at least one of limestone powder, coal gangue powder, and ferrite powder; And / or, the target void ratio of the asphalt mixture is 22.5%-23.5%.

8. A method for preparing an asphalt mixture, characterized in that: The method comprises the following steps: Obtaining raw material components of asphalt mixture, wherein the raw material components include conductive aggregate: asphalt matrix: filler in a mass ratio of 1: (0.03-0.05): (0.01-0.03); Preheating the asphalt matrix and the conductive aggregate separately and then performing a first mixing process to obtain a first mixture; The first mixture and filler are subjected to a second mixing treatment and then compacted to obtain the asphalt mixture.

9. The method for preparing an asphalt mixture according to claim 8, characterized in that: Preheating the asphalt matrix to a temperature of 165° C. to 180° C. for 2 h to 3 h; and / or, preheating the conductive aggregate to a temperature of 185° C.-195° C. for a period of 4 h-5 h; And / or, the temperature of the first mixing treatment is 170°C-175°C; And / or, the temperature of the second mixing treatment is 170°C-175°C; And / or, the compaction temperature is 155°C-160°C; And / or, the number of compaction is more than 50 times; And / or, the compaction includes double-sided compaction; And / or, the asphalt mixture is a continuously open-graded asphalt mixture.

10. An application of the asphalt mixture according to any one of claims 6-7 or the asphalt mixture prepared by the method according to any one of claims 8-9 in road self-repairing performance, electromagnetic shielding, road snow melting and de-icing, road weighing, and traffic volume monitoring.

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