Electrically conductive bituminous coating

Abstract

The present invention relates to the field of bituminous compositions and their functional additives. It concerns a bituminous coating comprising at least one electrically conductive filler, specifically selected from carbon nanoparticles. The invention also relates to a method for preparing this bituminous coating and its use for cooling electric vehicle batteries.

Description

Title of the invention: Electrically conductive bituminous coating Scope of the invention

[0001] The present invention relates to the field of bituminous compositions and their functional additives. It concerns a bituminous coating comprising at least one electrically conductive filler, in particular selected from carbon nanoparticles. The invention also relates to a method for preparing this bituminous coating and its use for the thermal management of electric vehicle batteries. Prior art

[0002] Thermal management of electric vehicle batteries is a fundamental technical challenge to ensure their proper functioning, safety, and durability. Lithium-ion batteries, which are currently the most widely used in electric vehicles, are particularly sensitive to temperature variations. During their use, especially during charging, discharging, or intensive driving phases, these batteries produce a significant amount of heat. This heat release is due to both internal electrochemical reactions and Joule heating losses.

[0003] The heat generated can accumulate rapidly, particularly during rapid charging or in hot outdoor environments. Lithium-ion batteries typically have an optimal operating temperature range between 20°C and 40°C. Outside this range, their performance decreases significantly. At temperatures between 45°C and 50°C, the internal components of the battery begin to degrade more rapidly, which can lead to a loss of capacity, reduced energy efficiency, decreased operating time, and even compromised safety.

[0004] It is therefore essential to maintain the batteries within their ideal temperature range to ensure rapid charging without damage, constant power and extended service life.

[0005] Existing thermal management solutions are mostly integrated into vehicles. The most widespread rely on the use of liquid cooling systems, in which a heat transfer fluid (often water / glycol) circulates around the batteries to absorb and dissipate heat. Other configurations use ventilation systems, employing forced air to cool the cells by convection.

[0006] Although liquid systems are efficient in terms of thermal performance, they have several limitations: their integration cost is high, their operation relies on active mechanical components that are susceptible to failure or leakage, and their maintenance is complex. Furthermore, their integration adds weight to the vehicle and complexity to the onboard system, which negatively impacts driving range.

[0007] Ventilation systems, on the other hand, are simpler and lighter, but significantly less efficient, particularly during fast charging or in hot climates. They are also directly powered by the vehicle's battery, which further reduces its range.

[0008] There is therefore a need to provide a thermal regulation or dissipation solution that is external to the vehicle and not integrated into its internal components. Such a solution would complement or replace the active cooling systems integrated into electric vehicles, whose effectiveness is limited by constraints of weight, range, complexity, and cost.

[0009] There is also a need to develop a localized thermal management system, the implementation of which is economically viable and which is capable of effectively regulating the temperature of electric vehicle batteries during parking and / or charging phases, particularly in hot or densely urbanized environments.

[0010] Finally, it is essential that this system consumes little energy while offering sufficient cooling capacity. Summary of the invention

[0011] According to a first aspect, the invention relates to a bituminous coating comprising at least a bitumen base, an electrically conductive filler chosen from carbon nanoparticles, and aggregates, the bituminous coating having a void percentage between 20 and 40%, preferably between 25 and 30%.

[0012] According to one embodiment, the carbon nanoparticles consist of primary particles having an average diameter between 5 and 500 nm, preferably between 10 and 200 nm, preferably still between 10 and 100 nm.

[0013] According to one embodiment, the carbon nanoparticles have a porous or non-porous structure.

[0014] According to one embodiment, the carbon nanoparticles have a specific surface area BET of less than 200 m2 / g, preferably between 10 and 100 m2 / g, preferably still between 20 and 80 m2 / g.

[0015] According to one embodiment, the carbon nanoparticles have a specific surface area BET greater than 200 m2 / g, preferably between 500 and 3000 m2 / g, preferably even more between 1000 and 1500 m2 / g.

[0016] According to one embodiment, the carbon nanoparticles have an electrical resistivity of between 0.01 and 2 Ohm / cm, preferably between 0.1 and 1 Ohm / cm.

[0017] According to one embodiment, the carbon nanoparticles are obtained by: - ​​incomplete combustion of heavy petroleum residues or natural gas at a temperature between 1400 and 2000 °C; - incomplete combustion of tar hydrocarbons; - incomplete combustion of natural gas on steel channels; - thermal decomposition of natural gas or light hydrocarbons in the absence of oxygen at a temperature between 800 and 1200°C; - thermal cracking of acetylene at temperatures exceeding 2000 °C; and / or - pyrolysis of methane at a temperature between 1000 and 2000°C in the absence of oxygen.

[0018] According to one embodiment, the aggregates are gravels with dimensions greater than 2 mm, preferably between 2 mm and 40 mm, more preferably between 5 mm and 25 mm, and preferably not comprising fine particles, in particular particles with a dimension less than or equal to 2 mm.

[0019] According to one embodiment, the bituminous coating comprises between 1% and 95% by weight of electrically conductive filler selected from carbon nanoparticles relative to the total weight of the bituminous coating.

[0020] According to one embodiment, the bituminous coating further comprises a copolymer based on conjugated diene motifs and aromatic monovinyl hydrocarbon motifs, preferably a styrene-butadiene-styrene copolymer.

[0021] According to another aspect, the invention relates to a method for preparing a bituminous coating according to the invention, the method comprising: - heating the bitumen base, preferably to a temperature between 140°C and 180°C; - the incorporation of the electrically conductive charge; - possibly heating the aggregates, preferably to a temperature ranging from 100°C to 180°C; - the mixing of aggregates with the bitumen base containing the electrically conductive filler.

[0022] According to another aspect, the invention relates to the use of a bituminous coating according to the invention in parking areas and / or charging stations for electric vehicles, in particular to dissipate the heat generated by the batteries of said vehicles during their parking and / or charging phase.

[0023] According to another aspect, the invention relates to the use of a bituminous coating according to the invention in urban roadways for the reduction of urban heat islands.

[0024] According to another aspect, the invention relates to a pavement system, preferably for parking and / or charging electric vehicles, comprising: - at least one layer of bituminous asphalt according to the invention, and - at least one power source configured to activate a heat transfer in said bituminous coating; - possibly one or more temperature, humidity, and / or presence sensors; and - possibly, a processing unit configured to automatically regulate heat transfer in the asphalt.

[0025] The Applicant has thus developed a bituminous coating characterized by specific thermal and electrical properties, and which can be integrated into thermal management systems, in order to address the problems related to the development of electric mobility and urban climate warming.

[0026] Thanks to its composition, including in particular conductive fillers such as carbon nanoparticles and a high void ratio, the coating according to the invention allows for localized and adaptable thermal regulation when used as a coating in urban areas, parking lots and / or charging stations for electric vehicles. Detailed description

[0027] According to a first aspect, the invention relates to a bituminous coating comprising at least: - a bituminous binder comprising at least a bitumen base and an electrically conductive filler selected from carbon nanoparticles; - aggregates. The bitumen base

[0028] For the purposes of this invention, the terms "bitumen", "bitumen base" and "bituminous binder" are used interchangeably and independently of each other. "Bitumen", "bitumen base" or "bituminous binder" refers to any composition consisting of one or more bitumen bases and possibly comprising one or more other constituents, said compositions being suitable for use in road applications, particularly in mixtures with aggregates and / or fillers.

[0029] Bituminous coatings according to the invention may contain one or more bitumens from different origins: bitumens of natural origin, those contained in deposits of natural bitumen, natural asphalt or oil sands, and those from the refining of crude oil, in particular by atmospheric and / or vacuum distillation of oil.

[0030] In the context of the invention, the bitumens are advantageously chosen from bitumens obtained from the refining of crude oil, in particular bitumens containing asphaltenes or pitches.

[0031] Bitumens can be obtained by conventional refining processes, in particular by direct distillation and / or vacuum distillation of petroleum. These bitumens may optionally be viscoreduced and / or deasphalted and / or air rectified. It is common practice to vacuum distill the atmospheric residues from the atmospheric distillation of crude oil. This manufacturing process therefore consists of a succession of atmospheric distillation and vacuum distillation, with the feedstock for the vacuum distillation corresponding to the residues from the atmospheric distillation. These vacuum residues from the vacuum distillation tower can also be used as bitumens.It is also common to inject air into a charge usually composed of distillates and heavy products from the vacuum distillation of atmospheric residues from petroleum distillation. This process yields a blown, semi-blown, oxidized, air-rectified, or partially air-rectified base.

[0032] Different bitumens obtained by refining processes can be combined in the compositions according to the invention to obtain the best compromise in terms of technical performance. In conventional processes for blending different bitumens, the mixture is blended at temperatures between 100°C and 200°C, preferably between 140°C and 200°C, and with agitation for a period of at least 10 minutes, preferably between 30 minutes and 10 hours, and more preferably between 1 and 6 hours. The temperature and duration of heating vary according to the quantity of bitumen used and are defined by standard NF EN 12594. Blown bitumens can be manufactured in a blowing unit by passing a flow of air and / or oxygen through a starting bitumen or mixture of bitumens. This operation can be carried out in the presence of an oxidation catalyst, for example, phosphoric acid.

[0033] Generally, blowing is carried out at high temperatures, on the order of 200 to 300°C, for relatively long periods typically between 30 minutes and 2 hours, continuously or in batches. The duration and temperature of blowing are adjusted according to the properties sought for the blown bitumen and according to the quality of the starting bitumen.

[0034] Bitumen can also be fluxed bitumen by the addition of volatile solvents, petroleum-based fluidizing agents and / or vegetable-based fluidizing agents.

[0035] Among the usable bitumens according to the invention, recycled bitumens can also be mentioned.

[0036] Bitumen can also be hard grade bitumen, such as grades 10 / 20, 20 / 30, or soft grade bitumen such as grade 160 / 220, as defined by standard EN 12591.

[0037] The bitumen is preferably a hard grade bitumen, advantageously a grade bitumen of 35 / 50, 50 / 70 or 70 / 100.

[0038] Preferably, the bituminous coating according to the invention comprises at least 4% by weight of bitumen base, relative to the total weight of the composition, preferably at least 5% by weight, more preferably at least 6% by weight, advantageously at least 8% by weight, and even more advantageously at least 10% by weight.

[0039] According to one embodiment, the bituminous coating comprises from 4% to 20% by weight of bitumen base, relative to the total weight of the composition, preferably between 5% and 10% by weight, preferably again between 6% and 8% by weight. The electrically conductive charge

[0040] The bituminous coating according to the invention comprises an electrically conductive filler. This filler is intended to give the bituminous matrix sufficient electrical conductivity for functional applications.

[0041] Advantageously, the electrically conductive charge comprises at least carbon nanoparticles.

[0042] Preferably, the carbon nanoparticles are non-graphitic, that is to say, they are not made up of ordered sheets of sp2 carbon in a hexagonal lattice, such as graphene.

[0043] According to a particular embodiment, the conductive charge comprises neither graphene nor carbon nanotubes.

[0044] According to a preferred embodiment, the conductive charge consists essentially of non-graphitic carbon nanoparticles, preferably as defined below.

[0045] According to a preferred embodiment, the carbon nanoparticles have a spherical or quasi-spherical morphology. By “quasi-spherical,” we mean a shape whose aspect ratio, defined as the ratio between the height and width of the particles, is less than 1.5.

[0046] Preferably, the carbon nanoparticles consist of primary particles having an average diameter between 5 nm and 500 nm, even more preferably between 10 nm and 200 nm, and particularly between 10 nm and 100 nm.

[0047] By "average diameter" is meant a statistical measure of the particle size distribution. In the context of the invention, this value corresponds to the median diameter (D50), defined as the diameter for which 50% of the particles have a size smaller than this value.

[0048] The diameter of the particles can be measured by different methods, such as laser diffraction (for example ISO 13320 standard), dynamic light scattering (DLS), image analysis (SEM / TEM), or sieving.

[0049] According to one embodiment, the primary particles can assemble into aggregates having an average size of between 50 nm and 600 nm. These aggregates can in turn form agglomerates with a size of between 1 pm and 100 pm.

[0050] By "primary particle," we mean an elementary particulate entity formed during the synthesis process, before any association or agglomeration with other particles. In the context of this invention, a primary particle refers to an individual particle, generally spherical or nearly spherical, which constitutes the basic unit of carbon nanoparticles. These particles can then associate through physicochemical interactions to form aggregates or agglomerates, without losing their inherent morphological identity.

[0051] Carbon nanoparticles can be porous or non-porous.

[0052] By "porous", for the purposes of the invention, means a particulate structure having a network of pores, whether open (accessible from the surface) or closed (enclosed within the particle), the cumulative volume of which is greater than 0.1 cm3 / g, as measured by standardized methods such as gas adsorption (for example according to the BET method) or mercury porosimetry.

[0053] Porosity can be of intraparticulate origin, that is to say located within the primary particles themselves, or interparticulate, resulting from the spatial organization of the particles among themselves within aggregates or agglomerates.

[0054] Preferably, the pores of the nanoparticles have a size between 2 nm and 300 nm, preferably between 10 nm and 200 nm.

[0055] According to an advantageous embodiment, the carbon nanoparticles have a specific surface area BET of between 10 m2 / g and 3000 m2 / g, preferably between 30 m2 / g and 2000 m2 / g.

[0056] According to a first variant, the specific surface area BET is less than 200 m2 / g, for example between 10 m2 / g and 100 m2 / g, more preferably between 20 m2 / g and 80 m2 / g.

[0057] According to a second variant, the specific surface area BET is greater than 200 m2 / g, in particular between 500 m2 / g and 3000 m2 / g, even more preferably between 1000 m2 / g and 1500 m2 / g.

[0058] The BET (Brunauer-Emmett-Teller) specific surface area is typically measured using the gas adsorption method (N2, CO2, ...), which is based on the analysis of the amount of gas adsorbed on the surface of a material.

[0059] Advantageously, the carbon nanoparticles have a carbon content greater than 95% by weight, preferably greater than 98% by weight and preferably even greater than 99% by weight.

[0060] Advantageously, the carbon nanoparticles have an ash content, determined by ASTM D1506, of less than 0.1%, preferably between 0.01% and 0.08%.

[0061] Advantageously, the carbon nanoparticles have a heavy metal (iron, nickel, copper) content of less than 10 ppm, preferably less than 5 ppm, as determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0062] Advantageously, carbon nanoparticles have an electrical resistivity ranging from 0.01 to 2 Ohm / cm, preferably ranging from 0.1 to 1 Ohm / cm.

[0063] Advantageously, carbon nanoparticles have an electrical conductivity ranging from 0.1 to 100 S / cm, preferably from 1 to 50 S / cm, more preferably from 2 to 20 S / cm.

[0064] According to one embodiment, carbon nanoparticles are obtained by partial combustion or thermal decomposition of liquid or gaseous hydrocarbons. These processes make it possible to produce various forms of carbon black possessing controlled physical and chemical characteristics.

[0065] In particular, carbon nanoparticles can be produced by: - incomplete combustion of heavy petroleum residues or natural gas at a temperature between 1400 and 2000 °C, (furnace black); - incomplete combustion of tar hydrocarbons (heavy oils) (lamp black); - Incomplete combustion of natural gas on steel channels (channel black); - thermal decomposition of natural gas or other light hydrocarbons in the absence of oxygen at a temperature between 800 and 1200°C (thermal black); - thermal cracking of acetylene at temperatures above 2000 °C (acetylene black); - pyrolysis of methane at a temperature between 1000 and 2000°C in the absence of oxygen.

[0066] Advantageously, the bituminous coating according to the invention comprises between 0.1% and 96% by weight, preferably between 1% and 70% by weight, preferably still between 5% and 50% by weight, preferably still between 10% and 30% by weight, of electrically conductive filler relative to the total weight of the bituminous coating.

[0067] The conductive filler can be incorporated into the bitumen base by any process known to those skilled in the art, in particular by mechanical mixing or ultrasonic dispersion at ambient temperature or at elevated temperature, preferably at elevated temperature. Once the conductive filler has been incorporated, the aggregates can then be added using conventional methods, in particular by mixing. The aggregates can, in particular, be heated before being incorporated into the bituminous binder. Additives

[0068] According to one embodiment, the bituminous binder further comprises one or more additional additives other than electrically conductive fillers. It may contain one or more bitumen elastomers such as copolymers based on conjugated diene units and aromatic monovinyl hydrocarbon units, such as SB (styrene-butadiene block copolymer), SBS (styrene-butadiene-styrene block copolymer), SIS (styrene-isoprene-styrene), SBS* (styrene-butadiene-styrene star block copolymer), SBR (styrene-butadiene-rubber), and EPDM (modified ethylene propylene diene). These elastomers may also be crosslinked by any known process, for example, with sulfur.We can also mention elastomers made from styrene monomers and butadiene monomers allowing crosslinking without crosslinking agent as described in documents WO2007 / 058994, WO2008 / 137394 and by the applicant in patent application WO2011 / 013073. .

[0069] Other additional additives known to those skilled in the art may be added. By way of example, the following additives may be mentioned: a. Bonding agents and / or surfactants. These are generally selected from alkylamine derivatives, alkylpolyamine derivatives, alkylamidopolyamine derivatives, and quaternary ammonium salt derivatives, used alone or in mixtures. The quantity of bonding agents and / or surfactants present in the bitumen / polymer composition is, for example, between 0.2% and 2% by weight, preferably between 0.5% and 1% by weight, relative to the total mass of the bitumen / polymer composition. b. waxes of animal or vegetable origin or hydrocarbon waxes, in particular long-chain hydrocarbon waxes, for example waxes of Polyethylene or paraffins, possibly oxidized. Amide waxes, such as ethylene bis(stearamide), may also be added, i.e., paraffins with chain lengths of 30 to 120 carbon atoms (C30 to C120). The paraffins are selected from polyalkylenes. Preferably, the paraffins are polymethylene paraffins and polyethylene paraffins. These paraffins may be of petroleum origin or may come from the chemical industry. Preferably, the paraffins are synthetic paraffins derived from the conversion of biomass and / or natural gas. d. fluxes, such as oils based on animal and / or vegetable fats or hydrocarbon oils of petroleum origin. Oils of animal and / or vegetable origin may be in the form of free fatty acids, triglycerides, diglycerides, monoglycerides or in esterified form, for example as methyl ester. e. resins of plant origin, such as rosin. f. antifoaming additives, including (but not limited to) polysiloxanes, oxyalkylated polysiloxanes and fatty acid amides derived from vegetable or animal oils. g. detergent additives and / or corrosion inhibitors, including (but not limited to) those selected from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkylpolyamines, polyetheramines and imidazolines. h. sliding agents or anti-wear agents, including (but not limited to) those selected from the group consisting of fatty acids and their ester or amide derivatives, including glyceryl monooleate, and mono- and polycyclic carboxylic acid derivatives. i. additives modifying crystallization, additives inhibiting paraffin deposits, additives for lowering the pour point; low-temperature rheology modifiers, such as ethylene / vinyl acetate (EVA) and / or ethylene / vinyl propionate (EVP) copolymers, ethylene / vinyl acetate / vinyl versatate (EA / AA / EOVA) terpolymers; ethylene / vinyl acetate / alkyl acrylate terpolymers; graft-modified EVA copolymers; polyacrylates; acrylate / vinyl acetate / maleic anhydride terpolymers; amide copolymers of maleic anhydride / alkyl (meth)acrylate capable of being obtained by reaction of a maleic anhydride / alkyl (meth)acrylate copolymer and an alkylamine or polyalkylamine having a hydrocarbon chain of 4 to 30 carbon atoms, preferably of 12 to 24 carbon atoms; α-olefin / maleic anhydride copolymers that can be obtained by reaction of an α-olefm / maleic anhydride copolymer and an alkylamine or polyalkylamine, the α-olefin being selectable from C10-C50 α-olefins, preferably C16-C20 α-olefins, and the alkylamine or polyalkylamine advantageously having a hydrocarbon chain of 4 to 30 carbon atoms, preferably 12 to 24 carbon atoms. j. antioxidants, for example of the hindered phenolic type or of the amino type, of the alkylated para-phenylenediamine type. k. Metal passivators. 1. Acidity neutralizers. m. Additives that lower the mixing temperature of asphalts and asphalt mixes, and those that improve the adhesion of bituminous binders to fillers and aggregates, such as, for example, polyisobutylene succinimides. n. acids, such as polyphosphoric acid, or diacids, especially fatty diacids.

[0070] Additives can be used in quantities well known to those skilled in the art, depending on the nature of the additive and the properties expected.

[0071] Preferably, when present, the content of additives varies from 0.1% to 10% by weight, preferably from 0.5% to 5% by weight, more preferably from 0.5% to 3% by weight, relative to the total weight of the bituminous binder. Bituminous coating according to the invention

[0072] The bituminous coating according to the invention preferably has a high percentage of voids and the coating is therefore a draining coating.

[0073] The presence of voids in the bituminous coating according to the invention creates a structure which allows water to infiltrate into an underlying or lateral layer, thus preventing water stagnation on the surface.

[0074] Advantageously, the percentage of voids in the bituminous coating according to the invention is between 20% and 40%, preferably between 25% and 30%.

[0075] The void content in asphalt can be defined as the ratio between the volume of voids and the total volume of the asphalt, expressed as a percentage. These voids can be measured by comparing the apparent density (including voids) and the actual density (excluding voids) of the mix. A low void content, generally less than 10%, ensures optimal compaction and watertightness, while a high void content, as in porous asphalt mixes, produces porous mixes that promote water drainage.

[0076] The determination of the percentage of voids in the asphalt can be carried out according to specific standards, such as NF EN 12697-6 and NF EN 12697-8.

[0077] The percentage of empty space can be calculated using the following formula: [°° 78 1 1^ = 100

[0079] where Vm is the percentage of void (in %), pmv is the actual density (in kg / m3) and pb is the apparent density (in kg / m3).

[0080] The apparent density is typically measured on a compacted test specimen. It includes the voids present in the composition. This measurement can be carried out by weighing a sample of the composition in air and in water to calculate its apparent volume using Archimedes' principle.

[0081] The actual density corresponds to the density of the composition without any voids. It is typically determined after disintegration of the sample and then using a pycnometer filled with water or another fluid.

[0082] According to one embodiment, the bituminous coating comprises, preferably consists essentially of: - 4% to 20% bitumen base, preferably between 5% and 10%; - 1% to 30% by weight of electrically conductive filler, preferably between 5 % and 15%; and - 50 to 95% by weight of aggregates, preferably between 70% and 90%, - the percentages are expressed in relation to the total weight of the asphalt bituminous.

[0083] Preferably, the bituminous coating according to the invention comprises aggregates consisting mainly of gravel, in particular recycled millings, of dimensions greater than 2 mm, preferably between 2 mm and 40 mm, more preferably between 5 mm and 25 mm.

[0084] The size of the aggregates, called particle size distribution, can be defined by a range indicated in the form X / Y mm, where X corresponds to the minimum size at which smaller particles are eliminated and Y corresponds to the maximum size at which only particles that can pass through a Y mm sieve are retained. In other words, an aggregate with a particle size distribution of 6 / 10 mm contains only particles with a diameter between 6 mm and 10 mm.

[0085] Among the usable particle sizes in the asphalt according to the invention, examples include 6 / 10 mm, 10 / 20 mm, and 20 / 40 mm.

[0086] Preferably the coating comprises a reduced or zero proportion of sand and / or fine particles, in particular with sizes less than or equal to 2 mm, more particularly less than 1 mm, or even less than 0.5 mm.

[0087] Unlike conventional asphalt mixes which contain a significant proportion of sand and fines, the asphalt mix according to the invention preferably comprises a reduced, or even zero, proportion of fine particles. For example, the asphalt mix may comprise less than 10% by weight of particles < 2 mm, preferably less than 5%, and more preferably less than 2% by weight.

[0088] The absence or very low proportion of fines promotes a higher void ratio and better water drainage capacity. This formulation choice makes the asphalt particularly suitable for porous asphalt applications, notably in urban roads, cycle paths, pedestrian zones, or permeable parking lots.

[0089] The bituminous mix according to the invention can be prepared by any process known to those skilled in the art. Generally, these processes include mixing the components and heating the mixture. The bitumen is usually heated before mixing, and the other components are added gradually according to their nature and their role in the composition.

[0090] According to another aspect, the invention relates to a method for preparing a bituminous coating as described above, the method comprising at least the following steps: - heating of the bitumen base, preferably to a temperature between 140°C and 180°C; - incorporation of the electrically conductive charge; - possibly heating of the aggregates, preferably at a temperature ranging from 100°C to 180°C, preferably from 120°C to 180°C; - mixing of the aggregates with the bitumen base containing the conductive filler. Applications and uses

[0091] The bituminous coating according to the invention has specific thermal and electrical properties which make it particularly suitable for applications in the field of electric vehicles, and more generally in high energy performance urban infrastructures.

[0092] Bituminous asphalt is preferably intended for use in parking areas, fast charging stations, smart car parks or technical pavements designed to integrate thermal regulation, localized cooling or heat dissipation functions.

[0093] Thanks to its optimized internal structure, including thermal and / or electrical conductivity, a high void ratio, and drainage or retention properties, the asphalt according to the invention makes it possible to manage, modulate or redistribute heat, both on the surface and in depth, in response to local thermal conditions or to the needs of surrounding equipment, in particular the batteries of parked electric vehicles.

[0094] According to a first embodiment, the bituminous coating is used to provide passive cooling by water evaporation. This embodiment preferably relies on a multilayer structure comprising at least: - a top layer consisting of a drainage coating according to the invention, having a void percentage typically between 20% and 40%, and arranged to capture and temporarily retain water, in particular from precipitation or from a recovery system; - a lower layer, non-draining or waterproof, placed immediately below the drainage layer, intended to limit the vertical infiltration of water into the subsoil and to form a temporary reservoir within the thickness of the structure.

[0095] Under the influence of ambient heat, or the heat emitted by a parked vehicle, the water contained in the upper layer gradually evaporates. This endothermic phenomenon results in localized heat absorption, passively cooling the parking area, and in particular the batteries of parked vehicles. This embodiment is particularly well-suited to passive heat dissipation in charging stations or parking lots without active power supply.

[0096] According to a variant of this first embodiment, the lower layer may include an integrated heating system, for example in the form of electrical resistances or heating fluid circuits, allowing the evaporation of water to be initiated or accelerated when necessary, for example during periods of high heat or during a programmed thermal cycle.

[0097] According to a second embodiment, the bituminous coating is integrated into a functional multilayer structure, forming an active heat transfer system based on the Peltier effect. This system preferably comprises: - a top layer made of a conductive bituminous coating according to the invention, configured to act as a heat exchange surface capable of absorbing or emitting heat depending on the polarity of the applied current; - a lower layer also made of a conductive bituminous coating according to the invention, intended to dissipate heat towards the ground or towards a technical regulating layer; - an intermediate layer disposed between the two aforementioned layers, preferably comprising a semiconductor material incorporated in a polymer or bituminous matrix, so as to form a functional thermoelectric junction.

[0098] When this structure is subjected to an electric current, a thermal gradient is generated between the two layers of coating: a cold zone forms on the surface, absorbing heat from the batteries of parked vehicles, while a hot zone is generated in depth, where the heat is evacuated or recovered.

[0099] The system of the second embodiment can be reversible. By reversing the polarity of the applied current, the upper layer becomes a heat source, which makes it possible to use this configuration for de-icing parking areas in winter, or for preheating batteries in cold conditions, in order to improve their performance.

[0100] According to a third embodiment, the bituminous coating is integrated into an intelligent thermal management system capable of dynamically adapting its operation to environmental conditions or vehicle needs. This system includes: - a source of electrical power; - possibly, one or more sensors, such as temperature, humidity, or presence detection sensors; and - possibly, a control unit configured to control the thermal operation of the asphalt, according to predefined or measured parameters.

[0101] This system allows the cooling or heating functions to be activated, adjusted or deactivated only when needed, ensuring optimized energy efficiency and targeted thermal protection of sensitive components, including the batteries of electric vehicles parked or charging.

[0102] The bituminous mix according to the invention can also be used in urban roadways, in addition to the vehicle-related application described above, to reduce urban heat islands. According to one embodiment, the mix can also incorporate light-colored aggregates on its surface, and / or aggregates that have undergone reflective treatment, in order to reduce the absorption of solar radiation; and / or a passive or activated water evaporation system, as described previously.

[0103] The systems described above can be coupled to peripheral systems, such as, for example: - water recovery and redistribution networks, to replenish the drainage layer during hot periods; - photovoltaic panels, designed to provide the energy needed for thermal activation; and / or - buried thermal networks, allowing the captured heat to be stored or reused.

[0104] It is therefore an object of the invention the use of a bituminous coating according to the invention, in parking areas and / or charging stations for electric vehicles, in particular to dissipate the heat generated by the batteries of said vehicles during their parking and / or charging phase.

[0105] The use of such a bituminous coating in urban roadways, in particular with a view to reducing urban heat islands, is also an object of the invention.

[0106] Also an object of the invention is a pavement system, preferably intended for parking and / or charging electric vehicles, comprising: - at least one layer of bituminous asphalt according to the invention, - at least one power supply configured to activate heat transfer in the bituminous asphalt, - possibly, one or more temperature, humidity, and / or presence sensors, - and possibly, a processing unit configured to automatically regulate heat transfer in the bituminous mix according to measured conditions or a predefined program.

Claims

Demands

1. Bituminous coating comprising at least a bitumen base, an electrically conductive filler selected from carbon nanoparticles, and aggregates, the bituminous coating having a void percentage of between 20 and 40%, preferably between 25 and 30%.

2. Bituminous coating according to claim 1, wherein the carbon nanoparticles consist of primary particles having an average diameter between 5 and 500 nm, preferably between 10 and 200 nm, preferably again between 10 and 100 nm.

3. Bituminous coating according to claim 1 or claim 2, wherein the carbon nanoparticles have a porous or non-porous structure.

4. Bituminous coating according to any one of the preceding claims, wherein the carbon nanoparticles have a specific surface area BET of less than 200 m2 / g, preferably between 10 and 100 m2 / g, preferably still between 20 and 80 m2 / g.

5. Bituminous coating according to any one of the preceding claims, wherein the carbon nanoparticles have a specific surface area BET greater than 200 m2 / g, preferably between 500 and 3000 m2 / g, preferably still between 1000 and 1500 m2 / g.

6. Bituminous coating according to any one of the preceding claims, wherein the carbon nanoparticles have an electrical resistivity of between 0.01 and 2 Ohm / cm, preferably between 0.1 and 1 Ohm / cm.

7. Bituminous coating according to any one of the preceding claims, wherein the carbon nanoparticles are obtained by: - Incomplete combustion of heavy petroleum residues or natural gas at a temperature between 1400 and 2000 °C; - Incomplete combustion of tar hydrocarbons; - Incomplete combustion of natural gas on steel channels; - Thermal decomposition of natural gas or light hydrocarbons in the absence of oxygen at a temperature between 800 and 1200 °C; - Thermal cracking of acetylene at temperatures above 2000 °C; and / or - Pyrolysis of methane at a temperature between 1000 and 2000 °C in the absence of oxygen.

8. Bituminous coating according to any one of the preceding claims, wherein the aggregates are gravels of dimensions greater than 2 mm, preferably between 2 mm and 40 mm, more preferably between 5 mm and 25 mm, and preferably not comprising fine particles, in particular particles of dimension less than or equal to 2 mm.

9. Bituminous coating according to any one of the preceding claims, comprising between 1% and 95% by weight of electrically conductive filler selected from carbon nanoparticles relative to the total weight of the bituminous coating.

10. Bituminous coating according to any one of the preceding claims, further comprising a copolymer based on conjugated diene motifs and aromatic monovinyl hydrocarbon motifs, preferably a styrene-butadiene-styrene copolymer.

11. A method for preparing a bituminous mix according to any one of the preceding claims, the method comprising: - heating the bitumen base, preferably to a temperature between 140°C and 180°C; - incorporating the electrically conductive filler; - optionally heating the aggregates, preferably to a temperature from 100°C to 180°C; - mixing the aggregates with the bitumen base containing the electrically conductive filler.

12. Use of a bituminous coating according to any one of claims 1 to 10 in parking areas and / or

13.

14. charging stations for electric vehicles, preferably to dissipate the heat generated by the batteries of said vehicles during their parking and / or charging phase. Use of bituminous asphalt according to any one of claims 1 to 10 in urban pavements for the reduction of urban heat islands. A roadway system, preferably for parking and / or charging electric vehicles, comprising: - at least one layer of bituminous asphalt according to any one of claims 1 to 10, and - at least one power supply configured to enable heat transfer in said bituminous coating; - possibly one or more temperature, humidity, and / or presence sensors; and - possibly, a processing unit configured to automatically regulate heat transfer in the bituminous mix.