Manufacturing method of inorganic fillers for roads and method of controlling road heat based on phase change materials using them

Abstract

The present invention relates to a method for manufacturing an inorganic filler for roads and a phase change material-based road thermal control method using the same. More specifically, the invention relates to a method for manufacturing an inorganic filler for roads in which mechanical strength and energy conversion performance are balanced by synthesizing single-phase vanadium dioxide using a carbon reduction method that facilitates high-quality, large-scale synthesis, grinding the vanadium dioxide to a size of several micrometers, and establishing optimal mixing conditions between ceramic powders. By applying the inorganic filler according to the present invention to road structures, it is possible to reduce power consumption by up to 60-90% compared to existing external power-dependent systems.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing an inorganic filler for roads and a method for controlling road heat based on a phase change material using the same. Background Technology

[0003] With the recent full-scale expansion of Zero Energy Buildings (ZEB) and Building Energy Certification (BEEC) schemes, there is a rapidly increasing demand for high-performance materials equipped with energy harvesting capabilities that can actively convert natural energy sources such as solar power, radiant heat, and geothermal heat, moving beyond passive building materials that merely block heat loss. As a response to this demand, there is a growing need for road pavement materials that go beyond simple physical load-bearing functions to harvest energy autonomously or minimize external energy consumption.

[0004] However, most of the existing road heating systems currently being introduced are powered by external electricity, which leads to the problem of excessive maintenance costs. In fact, it has been found that the annual electricity cost per square meter (㎡) for existing road heating systems exceeds 30,000 won, posing a problem where the burden of operating costs outweighs energy efficiency in the long run.

[0005] Meanwhile, vanadium dioxide (VO2) is a representative MIT material that undergoes a phase transition at approximately 67°C, close to room temperature, changing from an insulator to a conductor. Through this phase transition, vanadium dioxide (VO2) undergoes changes in electrical, optical, and thermal properties, and is utilized in high-performance devices and products. However, VO2 is currently mainly manufactured through hydrothermal synthesis or hydrogen reduction methods, and due to complex processes and low yields, it is difficult to utilize it in large areas or large volumes, which limits its application to thin-film-based high-value devices.

[0006] Accordingly, the inventors developed a technology capable of efficiently synthesizing VO₂ microparticles and stably dispersing them so that they can be applied as inorganic fillers for road paving. Furthermore, by mixing the VO₂ particles with ceramic powder applied together, an optimal mixing ratio was derived that balances energy conversion characteristics and mechanical performance within the inorganic binder. The present invention was completed by developing an inorganic filler that, when the filler mixed at the above ratio is applied to a road paving structure, possesses the function of actively converting thermal energy into electrical energy while simultaneously ensuring mechanical durability against vehicle loads, wear, and environmental stress. Prior art literature

[0008] Chinese Public Patent CN 116924469 The problem to be solved

[0009] The present invention has been devised to solve the above-mentioned problems, and the objective of the present invention is to provide a method for synthesizing vanadium dioxide that is efficient, maintains high quality, and enables mass production.

[0010] Another objective of the present invention is to establish optimal mixing conditions between vanadium dioxide particles applicable as inorganic fillers for roads and ceramic powder to implement uniform dispersion technology and to provide a filler in which mechanical strength and energy conversion performance are balanced.

[0011] Another objective of the present invention is to construct an energy-independent road system through an energy-harvesting type filling structure capable of operating without an external power source, and to improve safety during the winter season.

[0012] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0014] To achieve the above objective, the present invention provides a method for manufacturing an inorganic filler for roads, characterized by comprising the steps of: preparing a raw material mixture by mixing vanadium pentoxide (V2O5) and a carbon material; preparing vanadium dioxide (VO2) by placing the raw material mixture in a crucible and heating it while flowing an inert gas; grinding the prepared vanadium dioxide; and preparing an inorganic filler for roads by mixing ceramic powder with the ground vanadium dioxide.

[0015] In one embodiment of the present invention, the step of producing vanadium dioxide (VO2) by placing the raw material mixture in a crucible and heating it while flowing an inert gas may be to produce vanadium dioxide (VO2) by heating it at 800 to 1200 ℃ for 5 to 15 hours.

[0016] In one embodiment of the present invention, the step of grinding the prepared vanadium dioxide can be performed at 500 to 1000 RPM for 1 to 5 hours.

[0017] In one embodiment of the present invention, the step of manufacturing an inorganic filler for roads by mixing ceramic powder with the pulverized vanadium dioxide may involve mixing 35 to 85 parts by weight of the vanadium dioxide and 15 to 65 parts by weight of the ceramic powder based on 100 parts by weight of the total inorganic filler for roads.

[0018] To achieve the above objective, the present invention provides an inorganic filler for roads characterized by comprising vanadium dioxide, ceramic powder, a silane coupling agent, an inorganic filler, an elastic polymer, and a conductive filler.

[0019] In one embodiment of the present invention, the inorganic filler for roads may comprise, with respect to 100 parts by weight of vanadium dioxide, 15 to 200 parts by weight of the ceramic powder, 0.5 to 5 parts by weight of the silane coupling agent, 5 to 30 parts by weight of the inorganic filler, 5 to 20 parts by weight of the elastic polymer, and 0.1 to 10 parts by weight of the conductive filler.

[0020] To achieve the above objective, the present invention provides a method for controlling road heat based on a phase change material, characterized by comprising the steps of: dissolving an inorganic road filler in a solvent to prepare a liquid filler composition; burying the liquid filler composition and drying it to form a vanadium dioxide (VO₂)-based filler layer; and forming a road pavement finishing layer on the vanadium dioxide-based filler layer.

[0021] In one embodiment of the present invention, in the step of preparing a liquid filling composition by dissolving the inorganic filler for roads in a solvent, the weight ratio of the inorganic filler for roads and the solvent may be 1:0.2 to 0.8.

[0022] In one embodiment of the present invention, in the step of burying the liquid filling composition and drying it to form a vanadium dioxide (VO₂)-based filling layer, the drying may be performed at a temperature of 40 to 80°C for 30 to 2 hours.

[0023] In one embodiment of the present invention, the filling layer may be formed with a thickness of 1 to 5 cm. Effects of the invention

[0025] According to the method for producing vanadium dioxide with controllable phase transition characteristics of the present invention, by means of the solution to the above problem, it is possible to synthesize large quantities of vanadium dioxide compared to general hydrothermal synthesis methods or hydrogen reduction methods, and to control phase transition characteristics more uniformly and efficiently.

[0026] By effectively controlling thermal energy generated on the road surface through the filler according to the present invention, the rise in road surface temperature in high-temperature environments during the summer is suppressed to reduce asphalt deformation and deterioration, and road surface freezing is delayed in low-temperature environments during the winter, thereby significantly improving safety. In particular, by actively harvesting solar radiation and geothermal heat naturally entering the road through the present invention, power consumption can be reduced by up to 60-90% compared to existing external power-dependent systems.

[0027] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0029] Figure 1 shows a flowchart of the overall synthesis process of vanadium dioxide. Figure 2 shows the (a) XRD and (b) DSC analysis results of pure VO2 prepared using the carbon reduction method. Figure 3 is a graph showing the particle size analysis results before and after ball milling. Figure 4 is a graph showing the results of the analysis of freezing delay performance according to changes in the thickness of the packing layer. Specific details for implementing the invention

[0030] The terms used in this invention have been selected based on currently widely used general terms, taking into account their functions within the invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0031] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0032] When a part of a specification is described as 'comprising' a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0033] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0035] The present invention will be described in detail below.

[0037] The present invention provides a method for manufacturing an inorganic filler for roads, characterized by comprising the steps of: preparing a raw material mixture by mixing vanadium pentoxide (V2O5) and a carbon material as shown in FIG. 1; preparing vanadium dioxide (VO2) by placing the raw material mixture in a crucible and heating it while flowing an inert gas; grinding the prepared vanadium dioxide; and preparing an inorganic filler for roads by mixing ceramic powder with the ground vanadium dioxide.

[0039] First, as an initial powder mixing step, a step of preparing a raw material mixture by mixing vanadium pentoxide (V2O5) and a carbon material can be performed.

[0040] The step of preparing a raw material mixture by mixing the vanadium pentoxide (V2O5) and the carbon material may involve mixing the vanadium pentoxide (V2O5) and the carbon material in a molar ratio of 1:1 to 5:1. Preferably, the vanadium pentoxide (V2O5) and the carbon material may be mixed in a molar ratio of 1:1 to 3:1, and more preferably, the vanadium pentoxide (V2O5) and the carbon material may be mixed in a molar ratio of 2:1, but is not limited thereto.

[0041] The above carbon material may be one or more selected from the group consisting of carbon black and graphite.

[0043] Next, as a step for producing vanadium dioxide through carbon reduction, the above raw material mixture can be placed in a crucible and heated while flowing an inert gas to produce vanadium dioxide (VO2).

[0045] As such, the present invention provides a method for producing vanadium dioxide using a carbon reduction method instead of the conventional hydrothermal synthesis method or hydrogen reduction method. The above method for producing vanadium dioxide enables the synthesis of large quantities of vanadium dioxide compared to general hydrothermal synthesis or hydrogen reduction methods, and allows for more uniform and efficient control of phase transition characteristics.

[0047] The step of producing vanadium dioxide (VO2) by placing the above raw material mixture in a crucible and heating it while flowing an inert gas can be performed by heating at a temperature of 800 to 1200 ℃ for 5 to 15 hours to produce vanadium dioxide (VO2).

[0048] The step of producing vanadium dioxide (VO2) by placing the above raw material mixture in a crucible and heating it while flowing an inert gas may include a step of creating a vacuum for at least 15 minutes using an oil pump before heating to block internal oxygen as much as possible, and a step of flowing the inert gas at a rapid rate of 0.6 to 1 L / min.

[0049] The inert gas for the above reducing atmosphere may be argon gas, but is not limited thereto.

[0050] The heating step may include a heating section in which the temperature is raised to 1000 ℃ at a rate of 200 ℃ / h, a holding section in which the temperature is heated to 1000 ℃ for 10 hours, and a cooling section in which it naturally cools down to room temperature for about 3 to 4 hours. The heating time may be varied depending on the amount of material being manufactured.

[0051] In the step of producing vanadium dioxide (VO2) by placing the above raw material mixture in a crucible and heating it while flowing an inert gas, the average particle size of the vanadium dioxide produced may be 50 to 200 μm. Preferably, it may be 50 to 100 μm, but is not limited thereto.

[0053] Next, as a step of controlling the particle size of vanadium dioxide through grinding, a step of grinding the manufactured vanadium dioxide can be performed.

[0054] The step of grinding the vanadium dioxide produced above may utilize equipment such as a ball mill or a jet mill, but is not limited thereto.

[0055] The step of grinding the vanadium dioxide produced above may be performed at 500 to 1000 RPM for 1 to 5 hours. Preferably, it may be performed at 700 to 800 RPM for 1 to 3 hours, but is not limited thereto. The operating speed and time may be optimized depending on the amount of material or the size of the balls.

[0056] The size of the vanadium dioxide particles can be controlled through the step of grinding the vanadium dioxide manufactured above.

[0057] In the step of grinding the vanadium dioxide produced above, the average particle size of the ground vanadium dioxide may be 1 to 20 μm. Preferably, it may be 1 to 10 μm, but is not limited thereto.

[0059] Next, a step of mixing ceramic powder with crushed vanadium dioxide can be performed, in which ceramic powder is mixed with the crushed vanadium dioxide to manufacture an inorganic filler for roads.

[0060] The ceramic powder mentioned above is an inorganic mineral generally included in cement, and may be an inorganic mineral having a mineral composition basis similar to Portland cement. For example, the ceramic powder may include various inorganic components used in road paving cement, such as feldspar, limestone, silica, kaolin, kaolin, talc, zinc oxide, magnesia, titania, zirconia, spinel-based oxide, maifan stone, zeolite, biotite, stucco, perlite, vermiculite, etc. Furthermore, the ceramic powder may further include inorganic powders derived from industrial by-products, such as fly ash, blast furnace slag, and silica fume.

[0061] The average particle size of the ceramic powder may be about 1 to 30 μm, and more preferably 1 to 15 μm. For example, the ceramic powder may comprise 28 to 32 weight% feldspar, 33 to 37 weight% limestone, 13 to 17 weight% zinc oxide powder, 4 to 6 weight% silica, 4 to 6 weight% kaolin, 4 to 6 weight% talc, and 4 to 6 weight% bioceramic material (a mixture of maifan stone, zeolite, and biotite), and may be used with an average particle size controlled to a range of about 1 to 15 micrometers (μm).

[0062] The ceramic powder can achieve optimal latent heat performance and durability depending on the mixing ratio with the vanadium dioxide. Based on 100 parts by weight of the total inorganic filler for roads, the mixture may consist of 35 to 85 parts by weight of the vanadium dioxide and 15 to 65 parts by weight of the ceramic powder. Preferably, based on 100 parts by weight of the total inorganic filler for roads, the mixture may consist of 35 to 65 parts by weight of the vanadium dioxide and 35 to 65 parts by weight of the ceramic powder; more preferably, based on 100 parts by weight of the total inorganic filler for roads, the mixture may consist of 35 to 50 parts by weight of the vanadium dioxide and 50 to 65 parts by weight of the ceramic powder.

[0064] The present invention provides a road inorganic filler characterized by being manufactured according to the above-described manufacturing method.

[0066] In one embodiment of the present invention, the inorganic filler for roads may comprise vanadium dioxide, ceramic powder, silane coupling agent, inorganic filler, elastic polymer, and conductive filler.

[0067] The vanadium dioxide (VO₂) mentioned above is a functional material capable of efficiently storing and releasing thermal energy, characterized by absorbing or releasing latent heat when the external temperature reaches a phase transition temperature of approximately 68°C. By utilizing this characteristic, when the above-mentioned inorganic filler for roads is applied to a road, it absorbs excessive heat from the road surface during the day to suppress a rapid rise in road surface temperature, and conversely, releases stored heat at night or during winter when the temperature drops to delay freezing. In other words, the above-mentioned inorganic filler according to the present invention can maintain a stable road environment by actively absorbing and releasing heat generated from the road surface, going beyond merely blocking it.

[0068] In particular, the inorganic filler for roads according to the present invention is characterized by simultaneously securing mechanical durability and thermal stability through mixing with ceramic powder so that it can operate stably even during the repetitive phase transition process of VO2. The ceramic powder uniformly disperses and fixes VO2 particles so that performance does not deteriorate even under repeated thermal shock over a long period of time, and also has the effect of preventing structural cracks by mitigating the difference in adhesion and thermal expansion coefficients with road pavements such as asphalt and concrete.

[0069] The ceramic powder may contain various inorganic components used in road paving cement, such as feldspar, limestone, silica, kaolin, kaolin, talc, zinc oxide, magnesia, titania, zirconia, spinel oxide, maifan stone, zeolite, biotite, stucco, perlite, and vermiculite. Furthermore, the ceramic powder may further include inorganic powders derived from industrial by-products, such as fly ash, blast furnace slag, and silica fume. Preferably, the average particle size may be controlled to be in the range of about 1 to 15 μm, and such ceramic powder plays a role in contributing to the improvement of thermal stability, durability, and compressive strength of the inorganic filler.

[0070] The above silane coupling agent is a substance that improves the interfacial bonding strength between inorganic particles and organic polymers, and plays a role in suppressing particle detachment and ensuring structural stability in a load-repeating environment. It is preferable to use aminosilane (3-aminopropyltriethoxysilane), epoxysilane (3-glycidoxypropyltrimethoxysilane), or mercaptosilane (3-mercaptopropyltrimethoxysilane) as the above silane coupling agent.

[0071] The above inorganic filler may be silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), titanium oxide (TiO₂), magnesium oxide (MgO), calcium oxide (CaO), zinc oxide (ZnO), or a mixture thereof. The above inorganic filler may be in the form of a powder with an average particle size ranging from 100 nanometers (nm) to 10 micrometers (µm), which is intended to ensure uniform dispersion and mechanical reinforcement effects within the composite material for road paving.

[0072] The above elastic polymer is a component for providing shock absorption and resilience, and may include various elastic materials such as epoxy-based resins, siloxane-based polymers, thermoplastic polyurethane (TPU), styrene-butadiene-styrene (SBS), and styrene-ethylene-butylene-styrene (SEBS). For example, polydimethylsiloxane (PDMS), a siloxane-based polymer, can provide excellent thermal stability, weather resistance, and high elasticity, while SBS and SEBS are block copolymers that provide wear resistance, flexibility, friction resistance, etc., and may be suitable for road paving materials in particular that require crack inhibition functions. More preferably, the above elastic polymer may be a polymer with an elastic modulus in the range of 2 to 10 GPa.

[0073] The conductive filler described above may include graphite, carbon black, nickel powder, carbon nanotubes (CNT), silver nanoparticles (AgNP), aluminum nitride, etc. These enhance phase transition responsiveness by forming porous pathways within the filler and serve to simultaneously improve thermal conductivity and electrical cohesion.

[0075] In one embodiment of the present invention, the inorganic filler for roads may comprise 15 to 200 parts by weight of the ceramic powder, 0.5 to 5 parts by weight of the silane coupling agent, 5 to 30 parts by weight of the inorganic filler, 5 to 20 parts by weight of the elastic polymer, and 0.1 to 10 parts by weight of the conductive filler, based on 100 parts by weight of the vanadium dioxide.

[0077] The above-mentioned inorganic filler for roads can be provided in various forms depending on the application method and usage environment, and can be broadly classified into dry powder filler type and liquid filler type.

[0078] In one embodiment according to the present invention, the filler may be a dry powder filler type in which all constituent components are fine powders in a solid state. The filler may be in a state in which vanadium dioxide, ceramic powder, inorganic filler, elastic polymer, conductive filler, etc., are uniformly mixed in advance. This has the advantage of being easy to transport and store, and can be stably applied even in environments sensitive to moisture or solvents.

[0079] In one embodiment according to the present invention, the filler may be a liquid filler type that can be mixed with a solvent. The liquid filler type can also be utilized as a repair material for filling micro-cracks or for road upper layer structures requiring precise application.

[0081] Meanwhile, the present invention provides a road heat control method based on a phase change material using the liquid filler type filler.

[0082] The above-described phase change material-based road heat control method may include the steps of: dissolving the above-described inorganic road filler in a solvent to prepare a liquid filler composition; burying the above-described liquid filler composition and drying it to form a vanadium dioxide (VO₂)-based filler layer; and forming a road pavement finishing layer on the vanadium dioxide-based filler layer.

[0084] First, the method may include the step of preparing a liquid filling composition by dissolving the above-mentioned inorganic road filler in a solvent. The solvent may be water, ethanol, propanediol, 1,6-hexanediol, 1,4-butanediol, isopropyl alcohol (IPA), or a mixture thereof, and more preferably may be a mixed solvent of isopropyl alcohol and ethanol.

[0085] The weight ratio of the inorganic filler for roads and the solvent may be 1:0.2 to 0.8. More preferably, the weight ratio of the inorganic filler for roads and the solvent may be 1:0.4 to 0.6.

[0087] Next, the method may include the step of burying the liquid filling composition and drying it to form a vanadium dioxide (VO₂)-based filling layer. This step allows solid components, such as vanadium dioxide, ceramic powder, and inorganic fillers contained in the liquid filling composition, to form a functional solid layer of the road.

[0088] The burial of the above liquid filling composition may involve applying the composition to the lower area of ​​the location where the road pavement finishing layer is to be formed.

[0089] After the above coating, the liquid filling composition may be dried at a temperature of 40°C to 80°C for 30 minutes to 2 hours. If the drying temperature is below the above range, the solvent evaporation rate is too slow, which delays curing and may cause mechanical non-uniformity within the filling layer due to the capture of some residual solvent. If the drying temperature exceeds the above range, microcracks or interfacial delamination may occur, leading to a decrease in the mechanical strength of the filling layer and problems such as the destruction of conductive pathways.

[0091] Next, the method may include the step of forming a road pavement finishing layer on the vanadium dioxide-based filler layer. This is a step of laminating a final finishing layer that supports physical loads from above and is exposed to the external environment after the vanadium dioxide-based filler layer has completely dried.

[0092] The above road pavement finishing layer may use high-strength materials such as general asphalt, polymer concrete, or cement mortar, and a primer or interface modifier may be applied if necessary.

[0093] In one embodiment of the present invention, the thickness of the vanadium dioxide-based filler layer and the road pavement finishing layer may be formed in a ratio of 1:0.5 to 1.5.

[0094] In one embodiment of the present invention, the vanadium dioxide (VO₂)-based filler layer may be formed with a thickness of 1 to 5 cm, and more preferably, the filler layer may be formed with a thickness of 2 to 3 cm. By optimizing the thickness of the filler layer, thermal stability can be secured, and at the same time, physical strength capable of stably withstanding external impact loads and mechanical stress caused by vehicle traffic can be secured. If the thickness of the filler layer is less than the above range, the phase change characteristics of VO₂ are not fully exhibited, resulting in insufficient heat capacity during the heat absorption and heat dissipation processes, which leads to a problem where the freezing delay effect on the road surface is limited. On the other hand, if the thickness of the filler layer exceeds the above range, non-uniform drying within the filler layer and structural defects such as cracks or delamination are prone to occur, which actually lowers mechanical strength and causes performance instability in environments subject to repeated thermal shock over a long period. Accordingly, the thickness of the filler layer may be formed within the above range to simultaneously improve thermal storage capacity and mechanical strength.

[0096] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0098] <Manufacturing Example> Manufacture of inorganic filler for roads

[0099] The initial powder V2O5 and carbon materials (carbon black, graphite, etc.) were mixed in a molar ratio of 2:1 and mixed for approximately 30 minutes using a mortar and pestle or rotary ball mill. After placing the mixed sample into a crucible, it was placed in a tubular electric furnace and heated for 6 to 10 hours at a temperature range of 800 to 1100 ℃ to synthesize VO2. During this process, argon gas was flowed at a rate of 0.6 to 1.0 L / min to create a reducing atmosphere. The heating conditions involved raising the temperature to 1000 ℃ at a rate of 200 ℃ / h, maintaining the 1000 ℃ for 10 hours, and then allowing it to cool naturally to room temperature for about 3 to 4 hours. To minimize the entry of internal oxygen, a vacuum was applied using an oil pump for at least 15 minutes prior to heating, and argon gas was flowed at a high rate of 1 L / min. 10 ml of 5 mm zirconia balls for grinding were placed in a container with 10 ml of synthesized VO2, and dry grinding was performed for 1 to 3 hours at 500 to 900 RPM using a high-energy ball mill (equipment such as a jet mill may be used if necessary) to grind the VO2 to an average particle size range of about 1 to 6 μm.

[0100] An inorganic filler for roads was manufactured by mixing the above-mentioned pulverized vanadium dioxide and ceramic powder, wherein the ceramic powder comprises 30 wt% feldspar, 35 wt% limestone, 15 wt% zinc oxide powder, 5 wt% silica, 5 wt% kaolin, 5 wt% talc, and 5 wt% bioceramic material (maifan stone, zeolite, and biotite), and the average particle size of the ceramic powder was adjusted to be in the range of about 1 to 15 μm.

[0101] As shown in Table 1 below, the ground VO₂ and ceramic powder were mixed in various weight ratios (e.g., 35:65, 50:50, 65:35, 85:15).

[0102] Next, a filler was prepared by mixing 3 parts by weight of 3-aminopropyltriethoxysilane, 8 parts by weight of SiO₂ and Al₂O₃, 12 parts by weight of SBS and SEBS, and 0.5 parts by weight of carbon black.

[0104] division Vanadium dioxide (parts by weight) Ceramic powder (parts by weight) Preparation Example 1.1 35 65 Preparation Example 1.2 50 50 Preparation Example 1.3 65 35 Preparation Example 1.4 85 15

[0106] <Experimental Example 1> XRD and DSC Analysis of Vanadium Dioxide

[0107] XRD and DSC analyses were performed on pure VO2 prepared using the carbon reduction method, and the results are shown in Figure 2.

[0108] Referring to Figure 2(a), it can be confirmed that the peak position of the XRD analysis is pure VO2 monoclinic (pre-phase transition phase) by comparing it with reference data.

[0109] Referring to Fig. 2(b), the peak location of the DSC analysis confirms that a phase transition occurs at 67°C upon heating and approximately 60°C upon cooling, which are the same as generally known values. This indicates that at these temperatures, a phase transition occurs from the low-temperature monoclinic phase to the high-temperature tetragonal structure, absorbing and releasing latent heat. At this time, the amount of heat entering or leaving can be calculated using the area under the graph, and the value is 51.6 J / g (or approximately 235 kJ / L), which is similar to the generally known value, confirming that high-quality VO2 is synthesized.

[0111] <Experimental Example 2> Particle Size Analysis of Vanadium Dioxide Before and After Ball Mill Treatment

[0112] Figure 3 shows the results of particle size analysis before and after ball milling, and illustrates the volume ratio according to particle size. Before ball milling (no ballmilled), the particle size of 92 μm was most frequently found, and after ball milling (ballmilled), the particle size of 4.6 μm was most frequently measured.

[0114] <Example 1>

[0115] A liquid filler composition was prepared by dissolving the filler materials prepared according to Preparation Examples 1.1 to 1.4 in a solvent. The solvent used was a mixture of isopropyl alcohol (IPA) and ethanol in a weight ratio of 7:3, and the filler material and the solvent were mixed in a weight ratio of 7:3. A test specimen was prepared by applying the liquid filler composition to a thickness of 1 cm, and then dried at a temperature of 60°C for 1 hour. Subsequently, asphalt was applied to the same thickness.

[0117] Hereinafter, road structure specimens using the filler prepared according to the above Manufacturing Examples 1.1 to 1.4 were named Examples 1.1 to 1.4.

[0119] <Experimental Example 3> Analysis of Freezing Delay and Endothermic Characteristics According to Mixing Ratio

[0120] The freezing delay time and endothermic and latent heat characteristics were measured for specimens prepared according to Examples 1.1 to 1.4 above. The freezing delay time was measured as the time until the specimen containing moisture began to freeze under -10℃ conditions, and the endothermic and latent heats were measured as the amount of heat absorbed (J / g) during the VO₂ phase change using a differential scanning calorimeter (DSC). The results are shown in Table 2 below.

[0122] division Freezing delay time (min) Endothermic latent heat (J / g) latent heat of heat radiation (J / g) Example 1.1 28 41.2 42.0 Example 1.2 35 51.0 50.5 Example 1.3 22 56.5 55.0 Example 1.4 13 58.2 57.3

[0124] As a result of the experiment, all of Preparation Examples 1.1 to 1.4 absorbed heat from the outside, with a distinct endothermic peak appearing at approximately 67.0°C when heated. Conversely, when cooling, the stored heat was released, with a heat dissipation peak observed at approximately 59.6°C.

[0125] The latent heat of VO₂, averaged from the measurements of Preparation Examples 1.1 to 1.4, is approximately 51 ± 2 J / g, which corresponds to a level capable of changing the temperature of 1 g of water by about 12°C. Meanwhile, as the VO₂ content increased, the latent heat values ​​during the endothermic and heat dissipation processes generally showed an increasing trend. In particular, Preparation Example 4, which contained up to 85 parts by weight of VO₂, showed the greatest energy storage and release capacity with an endothermic latent heat of 58.2 J / g. However, despite having the highest latent heat value, Preparation Example 4 was found to have the shortest freezing delay time at 13 minutes. Ceramic powder is a cementitious inorganic mineral that forms a hardened body through a hardening reaction in the presence of a mixed solvent and fixes VO₂ particles, enabling stable performance over a long period. Therefore, it is determined that if the VO₂ ratio becomes excessively high, the VO₂ particles are not properly structurally supported, which weakens the structural stability of the entire filler and reduces the freezing inhibition effect.

[0126] On the other hand, in Example 2, where VO₂ and ceramic powder were balanced, the endothermic latent heat remained at a sufficiently high level of 51.0 J / g, while the freezing delay time was the longest at 35 minutes. This is the result of an optimal combination of the thermal properties of VO₂ and the mechanical stabilization effect of the ceramic powder, indicating that it is the most advantageous composition for actual road fillers.

[0128] <Example 2>

[0129] A liquid filling composition was prepared by dissolving the specimens prepared according to Preparation Example 1.2 in a solvent. At this time, the solvent was a mixture of isopropyl alcohol (IPA) and ethanol in a weight ratio of 7:3, and the filling material and the solvent were mixed in a weight ratio of 7:3.

[0130] After preparing test specimens by applying the above liquid filling composition to a thickness of 1 cm, they were dried for 1 hour at different drying temperature conditions (40℃, 60℃, 80℃, 100℃, 120℃, and room temperature drying) as shown in Table 3 below.

[0132] division Drying temperature (°C) Example 2.1 60 Example 2.2 80 Example 2.3 40 Comparative Example 2.1 100 Comparative Example 2.2 120 Comparative Example 2.3 20

[0134] <Experimental Example 4> Analysis of Mechanical Strength and Dispersion Uniformity According to Drying Temperature

[0135] To evaluate the mechanical strength of the specimens prepared according to Examples 2.1 to 2.3 and Comparative Examples 2.1 to 2.3, five specimens produced under the same conditions were repeatedly measured using a compression tester, and the average value was calculated. In addition, the cross-section of each specimen was observed using a scanning electron microscope (SEM) and an optical microscope, and the dispersion uniformity was evaluated based on the dispersion state of VO₂ and ceramic particles. The evaluation criteria for dispersion uniformity were set to grades 1 to 5, where grade 1 indicates a state of extremely non-uniform dispersion due to severe particle aggregation, and grade 5 indicates the best state in which particles are uniformly dispersed.

[0137] division Mechanical strength (MPa) Variance uniformity (grades 1–5) Example 2.1 8.2 5 (very uniform) Example 2.2 8.7 4 Example 2.3 7.8 4 Comparative Example 2.1 6.9 3 Comparative Example 2.2 6.7 3 Comparative Example 2.3 6.2 2

[0139] As a result of the evaluation, Example 2.1, dried at 60°C, showed a compressive strength of 8.2 MPa and a dispersion uniformity of grade 5, confirming that the particles were most uniformly dispersed. This indicates that the balance between mechanical strength and dispersion characteristics was most stably secured under the conditions of Example 2.1. In the case of Example 2.2, dried at 80°C, the compressive strength recorded the highest value at 8.7 MPa, but the dispersion uniformity decreased slightly to grade 4. This is attributed to some VO₂ particles aggregating locally as the solvent evaporated rapidly due to high-temperature drying. Example 2.3, dried at 40°C, showed a compressive strength of 7.8 MPa and a dispersion uniformity of grade 4.

[0140] On the other hand, in the case of Comparative Example 2.1 (dried at 100°C), the compressive strength decreased to 6.9 MPa, and the dispersion uniformity was evaluated as Grade 3. This is interpreted as microcracks occurring inside the specimen due to the higher drying temperature. In addition, in the case of Comparative Example 2.2, dried at 120°C, the compressive strength was 6.7 MPa and the dispersion uniformity was evaluated as Grade 3, indicating that some cracking occurred due to rapid solvent evaporation. In the case of Comparative Example 2.3, naturally dried at room temperature, the compressive strength was the lowest at 6.2 MPa, and the dispersion uniformity was also evaluated as Grade 2, indicating that incomplete hardening due to insufficient drying and particle non-uniformity occurred simultaneously.

[0141] As a result, it can be seen that the mechanical strength and dispersion uniformity of the liquid-phase filling composition containing VO2 and ceramic powder vary significantly depending on the drying temperature. In particular, it was confirmed that a drying condition of 60°C is the optimal temperature for drying the filling composition according to the present invention.

[0143] <Example 3>

[0144] A liquid filling composition was prepared by dissolving the filler prepared according to Preparation Example 1.2 in a solvent. At this time, the solvent was a mixture of isopropyl alcohol (IPA) and ethanol in a weight ratio of 7:3, and the filler and the solvent were mixed in a weight ratio of 7:3.

[0145] Test specimens were prepared by applying the above liquid filling composition at different thicknesses (1, 2, 3, 4, 5 cm) as shown in Table 5 below, and then dried at 60°C for 1 hour.

[0147] division Filling layer thickness (cm) Example 3.1 1 Example 3..2 2 Example 3.3 3 Comparative Example 3.1 4 Comparative Example 3.2 5

[0149] <Experimental Example 5> Analysis of freezing delay performance according to changes in packing layer thickness

[0150] Test specimens prepared according to Examples 3.1 to 3.3 and Comparative Examples 3.1 to 3.2 were exposed to a chamber at -10°C, and the freezing delay time was evaluated by measuring the time required for the surface moisture to completely freeze. Five test specimens of each thickness were prepared under the same conditions, repeated measurements were taken, and the average value was calculated.

[0152] division Freezing delay time (minutes) Example 3.1 18 Example 3..2 34 Example 3.3 45 Comparative Example 3.1 42 Comparative Example 3.2 38

[0154] As shown in Figure 4, as the thickness of the packing layer increased, the freezing delay time tended to increase to some extent. In particular, the freezing delay time was longest at a thickness of 3 cm, which is attributed to the packing layer securing sufficient heat storage capacity to delay rapid cooling of the external environment.

[0155] However, at thicknesses of 4 cm or more, the freezing delay time tended to decrease. This is attributed to the fact that when the packing layer becomes excessively thick, internal drying unevenness and microcracks occur, leading to a decrease in heat transfer efficiency. Therefore, it was confirmed that the freezing delay performance of the packing layer according to the present invention is not optimized by simply increasing the thickness, and that the best freezing inhibition performance is exhibited at a thickness of approximately 3 cm.

[0157] Specific embodiments of the present invention have been examined so far. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the present invention.

Claims

Claim 1 The method is characterized by comprising the steps of: preparing a raw material mixture by mixing vanadium pentoxide (V2O5) and a carbon material; preparing vanadium dioxide (VO2) by placing the raw material mixture in a crucible and heating it while flowing an inert gas; grinding the prepared vanadium dioxide; and preparing an inorganic road filler by mixing ceramic powder with the ground vanadium dioxide. go, The ceramic powder comprises one or more types selected from the group consisting of feldspar, limestone, silica, kaolin, kaolin, talc, zinc powder, magnesia, titania, zirconia, spinel-based oxide, maifan stone, zeolite, biotite, stucco, perlite, and vermiculite. The step of manufacturing the above-mentioned inorganic filler for roads is characterized by mixing 35 to 85 parts by weight of vanadium dioxide and 15 to 65 parts by weight of ceramic powder based on 100 parts by weight of the total above-mentioned inorganic filler for roads. Method for manufacturing road weapon filler Claim 2 A method for manufacturing an inorganic filler for roads according to claim 1, wherein the step of placing the raw material mixture in a crucible and heating it while flowing an inert gas to produce vanadium dioxide (VO2) is characterized by heating at 800 to 1200 ℃ for 5 to 15 hours to produce vanadium dioxide (VO2). Claim 3 A method for manufacturing an inorganic filler for roads according to claim 1, wherein the step of grinding the manufactured vanadium dioxide is characterized by grinding at 500 to 1000 RPM for 1 to 5 hours. Claim 4 delete Claim 5 Includes vanadium dioxide, ceramic powder, silane coupling agent, inorganic filler, elastomeric polymer, and conductive filler do, The ceramic powder is characterized by comprising one or more types selected from the group consisting of feldspar, limestone, silica, kaolin, kaolin, talc, zinc powder, magnesia, titania, zirconia, spinel-based oxide, maifan stone, zeolite, biotite, stucco, perlite, and vermiculite. Road weapon filler Claim 6 In claim 5, the inorganic filler for roads is characterized by comprising, with respect to 100 parts by weight of vanadium dioxide, 15 to 200 parts by weight of the ceramic powder, 0.5 to 5 parts by weight of the silane coupling agent, 5 to 30 parts by weight of the inorganic filler, 5 to 20 parts by weight of the elastic polymer, and 0.1 to 10 parts by weight of the conductive filler. Claim 7 A phase change material-based road heat control method characterized by comprising: a step of preparing a liquid filling composition by dissolving the inorganic road filler of claim 5 in a solvent; a step of burying the liquid filling composition and drying it to form a vanadium dioxide (VO₂)-based filling layer; and a step of forming a road pavement finishing layer on the vanadium dioxide-based filling layer. Claim 8 A phase change material-based road thermal control method according to claim 7, characterized in that, in the step of preparing a liquid-phase filling composition by dissolving the inorganic road filler in a solvent, the weight ratio of the inorganic road filler to the solvent is 1:0.2 to 0.

8. Claim 9 A phase change material-based road thermal control method according to claim 7, wherein, in the step of burying the liquid filling composition and drying it to form a vanadium dioxide (VO₂)-based filling layer, the drying is performed at a temperature of 40 to 80°C for 30 to 2 hours. Claim 10 In claim 9, the phase change material-based road heat control method is characterized in that the filling layer is formed with a thickness of 1 to 5 cm.

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