electrically conductive bituminous composition

Abstract

The invention relates to a bituminous composition comprising at least one bitumen base and at least one electrically conductive filler, preferably selected from carbon nanoparticles. The invention also relates to the uses of said bituminous composition in the fields of road and airport infrastructure, and / or waterproofing membranes, as well as for surface de-icing and the thermal preconditioning of electric vehicle batteries.

Description

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

[0001] The present invention relates to the field of bituminous compositions and their functional additives. It concerns a bituminous composition comprising at least one electrically conductive filler, specifically selected from carbon nanoparticles. The invention also relates to a method for preparing this composition and its applications, particularly in road surfaces and waterproofing membranes, with uses such as frost prevention on road surfaces and / or thermal preconditioning of electric vehicle batteries. Prior art

[0002] Bitumen, the main hydrocarbon binder used in road construction and civil engineering, is an essential material thanks to its adhesion and sealing properties.

[0003] However, road and industrial infrastructure, such as bitumen pavements or waterproofing membranes, faces major challenges related to climatic variations, particularly in regions where temperatures fluctuate around the freezing point.

[0004] When water seeps into the pores of bitumen and freezes, it expands, generating internal pressure that weakens the structure. This phenomenon causes cracks to form, which are exacerbated by each freeze-thaw cycle. These cracks can develop into significant damage such as potholes in roads or the deterioration of waterproofing membranes in buildings. This damage not only compromises the durability of infrastructure but also increases maintenance costs.

[0005] To address these problems, technologies have been developed to heat roads and bitumen. They aim to prevent ice formation in winter and to reduce the thermal stresses responsible for cracking.

[0006] Among these technologies is the integration of heating cables directly under the bituminous surface. These cables produce heat when an electric current flows through them, thus keeping the pavement above freezing.

[0007] Another technology is that of heat exchangers. This solution relies on the integration of tubes containing a heat transfer fluid under the road surface. In summer, the bitumen captures solar energy and heats the fluid, which can be stored for later use. subsequent use. In winter, this heat is released to warm the roadway or supply other infrastructure such as neighboring buildings or swimming pools.

[0008] Despite their potential, these technologies must overcome several challenges before they can be deployed on a large scale. One of the main obstacles lies in the homogeneous distribution of heat across the entire road surface. Uneven distribution can lead to cold or overheated areas, compromising the system's efficiency.

[0009] Furthermore, the high installation cost remains a significant obstacle. Integrating these systems requires specific design and skilled labor, which considerably increases initial investments. In addition, these technologies require specialized maintenance to repair heating cables or service heat exchangers, thus increasing long-term costs. Finally, finding a viable business model for these projects remains a major challenge, particularly for their large-scale application.

[0010] There is therefore a need to develop solutions and materials capable of effectively resisting freeze-thaw cycles while retaining their functional properties in the long term.

[0011] These solutions should in particular limit the formation and propagation of cracks, while preserving the mechanical and thermal performance of the bitumen in the face of climatic stresses.

[0012] Another major challenge is to ensure a uniform distribution of heat over the entire surface of the pavement, in order to avoid cold or overheated areas that could compromise the efficiency of the system.

[0013] There is also a need to propose solutions that can be integrated into infrastructure without causing a significant increase in construction or maintenance costs, whether for roads, parking lots or buildings.

[0014] Furthermore, these solutions must be adapted to the specific needs of different applications, while minimizing their environmental impact. For example, the emergence of electric vehicles opens up new perspectives for the use of heating technologies in infrastructure.

[0015] Finally, to enable large-scale deployment, these solutions must be easy to implement and economically viable. Summary of the invention

[0016] According to a first aspect, the invention relates to a bituminous composition comprising at least a bitumen base and an electrically conductive charge selected from carbon nanoparticles.

[0017] 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.

[0018] According to one embodiment, the carbon nanoparticles have a porous or non-porous structure.

[0019] 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.

[0020] 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 still between 1000 and 1500 m2 / g.

[0021] 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.

[0022] 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 hydrocarbon; - 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.

[0023] According to one embodiment, the bituminous composition has a void percentage of less than 15%, preferably less than 10%, preferably even less than 8%.

[0024] According to one embodiment, the bituminous composition further comprises mineral and / or synthetic fillers having a size less than or equal to 50 pm, preferably less than or equal to 10 pm, the composition being an asphalt.

[0025] According to one embodiment, the bituminous composition further comprises aggregates, preferably the aggregates comprise gravel, sand and mineral and / or synthetic fillers, the composition being a bituminous mix.

[0026] According to one embodiment, the bituminous composition comprises between 0.1% and 96% by weight of electrically conductive filler relative to the total weight of the composition.

[0027] According to one embodiment, the bituminous composition further comprises a copolymer based on conjugated diene motifs and aromatic monovinyl hydrocarbon motifs, preferably a styrene-butadiene-styrene copolymer.

[0028] According to another aspect, the invention relates to a method for preparing a bituminous composition as described above, the method comprising at least one step of incorporating the electrically conductive charge into a bitumen base.

[0029] According to another aspect, the invention relates to an infrastructure system, such as a pavement system or a waterproofing membrane, preferably intended for the parking and / or charging of electric vehicles, comprising at least: - a bituminous composition as described above and below; - metallic wires and / or strips, preferably of copper and / or aluminum, incorporated in or around said bituminous composition; and - at least two metallic electrodes connected to the metallic wires and / or strips and configured to distribute an electric current in said bituminous composition.

[0030] According to another aspect, the invention relates to the use of a bituminous composition or system as described above and below, to prevent the formation of ice on road surfaces, car parks and / or airport runways and / or for the thermal pre-conditioning of electric vehicle batteries.

[0031] The Applicant has developed an innovative bituminous composition incorporating electrically conductive fillers, including carbon nanoparticles.

[0032] These charges act as resistive elements which, when an electric current passes through them, produce heat by Joule heating. This heat is then diffused uniformly throughout the bitumen, heating the surface. This heat is generated directly within the bituminous composition itself, eliminating the heat losses often associated with external systems.

[0033] Unlike existing systems requiring complex networks, the solution proposed by the present invention consists of integrating a conductive filler directly into the bituminous binder. This approach simplifies installation, reduces the need for additional infrastructure, and decreases maintenance requirements.

[0034] By directly heating the bituminous composition, this solution keeps surfaces free of ice and snow, while preventing damage caused by freeze-thaw cycles. It thus contributes to extending the durability and lifespan of infrastructure.

[0035] In addition, the bituminous composition can be used on various types of surfaces (roads, parking lots, roofs) without requiring significant adaptations. Detailed description

[0036] According to a first aspect, the invention relates to a bituminous composition comprising at least a bitumen base and an electrically conductive filler. The bitumen base

[0037] 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, and / or in building applications, particularly for waterproofing structures.

[0038] The bituminous compositions 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.

[0039] In the context of the invention, the bitumens are advantageously chosen from among the bitumens obtained from the refining of crude oil, in particular the bitumens containing asphaltenes or pitches.

[0040] 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.

[0041] 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 of mixing different Bitumen is produced at temperatures between 100°C and 200°C, preferably between 140°C and 200°C, with agitation for at least 10 minutes, preferably between 30 minutes and 10 hours, and more preferably between 1 and 6 hours. The temperature and heating time vary depending on the quantity of bitumen used and are defined by standard NF EN 12594. Blown bitumen can be manufactured in a blowing unit by passing a flow of air and / or oxygen through a starting bitumen or bitumen mixture. This operation can be carried out in the presence of an oxidation catalyst, such as phosphoric acid.

[0042] 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 desired properties of the blown bitumen and the quality of the starting bitumen.

[0043] Bitumen can also be fluxed bitumen by the addition of volatile solvents, petroleum-based fluidizing agents and / or vegetable-based fluidizing agents.

[0044] Among the usable bitumens according to the invention, recycled bitumens can also be mentioned.

[0045] 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.

[0046] The bituminous composition will preferably comprise a hard grade bitumen advantageously a grade bitumen of 35 / 50, 50 / 70 or 70 / 100.

[0047] Preferably, the bituminous composition 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.

[0048] According to one embodiment, the bituminous composition according to the invention 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.

[0049] Preferably, the bituminous composition according to the invention comprises at least 40% by weight of bitumen base, relative to the total weight of the composition, preferably at least 50% by mass, more preferably at least 60% by weight, advantageously at least 70% by weight, more advantageously at least 80% by weight, even more advantageously at least 85% by weight.

[0050] According to one embodiment, the bituminous composition of the invention comprises from 40% to 99.9% by weight of bitumen base, relative to the total weight of the composition, preferably from 65% to 99% by weight, more preferably from 70% to 95% by weight, advantageously from 80% to 90% by weight.

[0051] For low bitumen contents, for example between 4% and 20% by weight, these are generally bituminous mix compositions, where the bitumen acts as a binder to bind the aggregates and ensure the mechanical cohesion of the material. These formulations are commonly used in road infrastructure.

[0052] For high bitumen contents, for example between 40% and 99.9% by weight, the composition is intended for specific applications. For example, these binder-rich compositions are used as asphalt or in the manufacture of waterproofing membranes to protect surfaces against water and moisture.

[0053] Thus, the present invention applies equally to bituminous compositions of the coated type, in which bitumen plays a role as a binder, and to formulations rich in bitumen intended for uses such as asphalts and / or waterproofing membranes. The electrically conductive charge

[0054] The bituminous composition according to the invention comprises an electrically conductive filler. This filler is intended to impart to the bituminous matrix sufficient electrical conductivity for functional applications.

[0055] Advantageously, the electrically conductive charge comprises at least carbon nanoparticles.

[0056] Preferably, the carbon nanoparticles are non-graphitic, that is to say, they are not made up of ordered sp2 carbon sheets in a hexagonal lattice, such as graphene.

[0057] According to a particular embodiment, the conductive charge comprises neither graphene nor carbon nanotubes.

[0058] According to a preferred embodiment, the conductive charge consists essentially of non-graphitic carbon nanoparticles, preferably as defined below.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] Carbon nanoparticles can be porous or non-porous.

[0066] 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, measured by standardized methods such as gas adsorption (for example according to the BET method) or mercury porosimetry.

[0067] 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.

[0068] Preferably, the pores of the nanoparticles have a size between 2 nm and 300 nm, preferably between 10 nm and 200 nm.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Advantageously, the carbon nanoparticles have an ash content, determined by ASTM D1506, of less than 0.1%, preferably between 0.01% and 0.08%.

[0075] 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).

[0076] Advantageously, carbon nanoparticles have an electrical resistivity ranging from 0.01 to 2 Ohm / cm, preferably ranging from 0.1 to 1 Ohm / cm.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] Advantageously, the bituminous composition according to the invention comprises from 0.1% to 96% by weight of electrically conductive filler relative to the total weight of the bituminous composition.

[0081] 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 high temperature to ensure a homogeneous distribution of the conductive filler in the bituminous matrix. Additives

[0082] According to one embodiment, the bituminous composition according to the invention further comprises one or more additional additive(s), different from the electrically conductive fillers described above.

[0083] The bituminous composition of the invention may contain one or more bitumen elastomers such as copolymers based on conjugated diene units and aromatic monovinyl hydrocarbon units, such as, for example, 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 further 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.

[0084] Other additional additives known to those skilled in the art may be added to the bituminous composition according to the invention. 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 polyethylene waxes or paraffins, possibly oxidized. Amide waxes, such as ethylene bis(stearamide), may also be added. c. Paraffins with chain lengths of 30 to 120 carbon atoms (C30 to C120). The paraffins are chosen from among the 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;the amidated α-olefin / maleic anhydride copolymers that can be obtained by reaction of an α-olefin / 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 of 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.

[0085] The additives are used in quantities well known to those skilled in the art, depending on the nature of the additive, depending on the bituminous base and the expected properties.

[0086] Preferably, when present, the content of additional additives varies from 0.1% to 10% by mass, preferably from 0.5% to 5% by mass, more preferably from 0.5% to 3% by mass, relative to the total mass of the bituminous composition. Compositions according to the invention

[0087] The bituminous composition according to the invention preferably has a low percentage of voids, understood as the ratio between the volume of voids and the total volume of the composition, expressed as a percentage.

[0088] The void content in a bituminous mixture is typically defined as the ratio of the volume of voids to the total volume of the mixture, expressed as a percentage. These voids can be measured by comparing the apparent density (including voids) and the actual density (excluding voids) of the mixture. A low void content, generally less than 10%, is desirable for dense asphalt mixtures to ensure better compaction, increased strength, and optimal sealing, while a high void content, as in porous asphalt mixtures, typically around 20 to 30%, promotes water drainage.

[0089] The determination of the percentage of void in the bituminous composition can be carried out according to specific standards, such as NF EN 12697-6 and NF EN 12697-8.

[0090] The percentage of empty space can be calculated using the following formula: [°° 911 Vm = lOOx^L

[0092] 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).

[0093] 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.

[0094] 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.

[0095] According to one embodiment, the bituminous composition of the invention has a void percentage of less than 20%, preferably less than 10%, even more preferably less than 8%, or even less than 5%, and ideally less than 3%.

[0096] Advantageously, the percentage of empty space is between 0% and 10%, preferably between 0% and 8%, and even more preferably between 3% and 5%.

[0097] In particular cases, the composition may have a void percentage of zero or close to 0%.

[0098] A low void content in the composition promotes contact between conductive particles dispersed in the bituminous matrix.

[0099] This allows the formation of an electrical percolation network, that is to say a continuous three-dimensional network of carbon nanoparticles ensuring the macroscopic electrical conductivity of the material.

[0100] This percolating network is essential for the efficient transport of electrical charges through the composition.

[0101] Thus, when the volume of the voids is reduced, the carbon nanoparticles are close enough to form contact points or tunneling junctions, ensuring the continuity of the conduction path.

[0102] A zero or near-zero void ratio maximizes this effect and allows the bituminous matrix to be converted into a conductive binder.

[0103] According to a first embodiment, the composition of the invention comprises, preferably consists essentially of, a bitumen base and an electrically conductive filler as defined above.

[0104] In particular, the bituminous composition comprises, preferably consists essentially of: - from 40% to 99.9% by weight of bitumen base and - from 0.1% to 60% by weight of electrically conductive charge,

[0105] the percentages being expressed in relation to the total weight of the composition.

[0106] This embodiment corresponds to a conductive bituminous binder, usable as such or intended to be combined with other materials (for example aggregates or sealing layers).

[0107] In this case, the percentage of empty space is preferably very low, or even zero (0%).

[0108] According to a second embodiment, the composition of the invention comprises, preferably consisting essentially of, a bitumen base, an electrically conductive filler and a mineral and / or synthetic filler having a diameter less than or equal to 50 microns, preferably less than or equal to 10 microns.

[0109] In particular, the composition of the invention comprises, preferably consists essentially of: - from 4% to 20% by weight of bitumen base, - from 1% to 30% by weight of electrically conductive charge, and - 5% to 50% mineral and / or synthetic fillers having a diameter less than or equal to 50 pm, preferably less than or equal to 10 pm,

[0110] the percentages being expressed relative to the total weight of the composition.

[0111] The mineral and / or synthetic fillers may be selected from limestone, marble powder, fly ash, fine sand, blast furnace slag, chalk, silica, talc, dolomite, kaolin, calcined clay and mixtures thereof.

[0112] According to this second embodiment, the bituminous composition preferably does not include aggregates.

[0113] In this mode, the composition is of the asphalt type, without coarse aggregates. It is intended for waterproofing applications (roofs, terraces) or for coatings subject to low mechanical stress (car parks, metro stations).

[0114] The presence of fine particles allows a dense matrix, favorable to the formation of a conductive network.

[0115] According to a third embodiment, the bituminous composition preferably comprises essentially: - 4% to 20% bitumen base, - 1% to 30% by weight of electrically conductive charge and - from 50 to 95% by weight of aggregates,

[0116] the percentages being expressed relative to the total weight of the composition.

[0117] According to this third embodiment, the bituminous composition is a conductive bituminous mix. This composition is particularly suitable for applications such as road surfaces (wearing course, base course or intermediate course).

[0118] Preferably, the composition has a continuous granular matrix, characterized by a progressive particle size distribution without discontinuity, allowing optimal stacking and a reduction of voids.

[0119] This structure ensures a low percentage of void, preferably less than 10%, even more preferably less than 5%, and ideally less than 3%, again promoting electrical percolation.

[0120] For the purposes of this invention, a "continuous granular matrix" refers to an aggregate size distribution in which all granular fractions—coarse, intermediate, and fine—are present in a progressive and balanced manner. This distribution is characterized by a regular particle size distribution curve, without any discontinuities in the sizes. It allows for optimal packing of the aggregates: the smaller aggregates fill the gaps left by the larger ones, while the fines (sands and fillers) fill the remaining spaces. This reduces the volume of voids in the bituminous composition.

[0121] Preferably, the composition according to the invention comprises a mixture of aggregates including gravel (2 to 40 mm), such as limestone, granite or porphyry; sand (up to 4 mm), of siliceous or calcareous origin; and mineral and / or synthetic fillers (< 0.050 mm), such as limestone or cement powder.

[0122] The bituminous composition according to the invention can be prepared by any process known to those skilled in the art. In general, the steps include heating the bitumen, incorporating the conductive fillers, and possibly mixing with the other components (fine fillers, aggregates).

[0123] For example, for a composition comprising only a bitumen base and carbon nanoparticles, the bitumen is first heated, preferably to a temperature between 140 °C and 180 °C, then the carbon nanoparticles are incorporated under continuous stirring to ensure homogeneous dispersion.

[0124] For a composition also comprising mineral and / or synthetic fillers, these can be added after the incorporation of the carbon nanoparticles, preferably under mechanical agitation.

[0125] In the case of a composition comprising aggregates, these are generally preheated to a temperature similar to that of the bitumen before being mixed with the bituminous binder comprising the heated bitumen base and the carbon nanoparticles. The mixture can then be compacted. Applications and uses

[0126] The incorporation of an electrical charge as described above into the bituminous composition of the invention makes it possible to transform the composition into a conductive composite material. Thanks to the presence of a percolating network formed by the interconnection of the conductive particles in the bituminous matrix, the composition becomes capable of conducting an electric current.

[0127] When an electric current passes through the bituminous composition, it generates heat by Joule effect, according to the following relationship:

[0128] E = I 2 RT

[0129] where E is the heat produced, I is the intensity of the electric current, R is the electrical resistance of the composition and t is the time of application of the electric current.

[0130] The low void content of the composition, possibly in combination with a homogeneous dispersion of the conductive charge, ensures the formation of a three-dimensional conduction network ensuring a uniform distribution of heat through the structure.

[0131] This generated heat helps prevent ice formation in the bituminous structure by maintaining local temperatures above freezing. This prevents water present in the pores from freezing, thus avoiding internal stresses related to ice expansion, which are often responsible for cracking in materials exposed to thermal cycling. Furthermore, the temperature rise softens the bitumen locally, promoting the self-healing of microcracks through localized flow of the binder. This phenomenon significantly extends the service life of structures made from this composition by reducing maintenance interventions.

[0132] The conductive filler does not merely improve electrical conductivity. By enhancing the material's thermal properties, it also improves its mechanical strength, particularly in the face of freeze-thaw cycles and intense thermal stresses. Consequently, the bituminous composition according to the invention is particularly well-suited to environments subjected to extreme climatic conditions or high dynamic loads.

[0133] Thus, the present invention also relates to the use of carbon nanoparticles, as described above, as an electrical charge in a bituminous composition, to prevent and / or limit the formation of ice in winter on the surface or in the mass of said composition.

[0134] The invention also aims at the use of these nanoparticles to improve resistance to freeze-thaw cycles, and / or limit cracking, and / or extend the life of bituminous structures, in particular those which are exposed to mechanical and thermal stresses.

[0135] The bituminous composition according to the invention can be used in many applications.

[0136] In the field of road infrastructure, it can be implemented as a coating for roadways, car parks, sidewalks, metro stations, and / or airport runways.

[0137] In an airport application, the composition according to the invention ensures the operation of runways and parking areas even in cold weather, reducing operational delays and increasing safety.

[0138] The composition according to the invention can also be used as waterproofing membranes for flat roofs or civil engineering structures. It offers protection against water infiltration while resisting extreme climatic variations.

[0139] In this application, the presence of the conductive charge allows the waterproofing membrane itself to function as an integrated heating element. By applying an electric current to the structure, the heat generated by the Joule effect is dissipated directly into the bituminous mass, thus transforming the membrane into an active heating device. This heating capacity of the structure is particularly advantageous in winter.

[0140] To apply an electric current to the bituminous composition according to the invention, a specific system for generating an electric current through the composition can be integrated during its application.

[0141] The present invention also relates to a system comprising at least: - a bituminous composition according to the invention, - metallic wires and / or strips, preferably made of copper and / or aluminum, incorporated in or around said bituminous composition, and - at least two metallic electrodes connected to the metallic wires and / or strips to distribute an electric current in the bituminous composition.

[0142] The system may optionally further include one or a plurality of sensors, such as temperature, humidity, or presence detection sensors.

[0143] The system may further include one or more electronic control devices for regulating the intensity, voltage and duration of the applied electric current, thus ensuring optimized management of the delivered thermal power.

[0144] This system can be integrated at different levels of infrastructure. For example, in the case of roads, parking lots, metro stations and / or airport runways, it can be implemented in the lower layers or sub-layers during construction and / or renovation. In the case of waterproofing membranes, it can be integrated at the time of application of the membrane to the substrate, whether it be a building or a civil engineering structure.

[0145] According to a particular embodiment, the bituminous composition and the system described above are used in parking lots, and more specifically in parking spaces, for the thermal preconditioning of electric vehicle batteries. When an electric vehicle is parked, a current can be applied to the bituminous composition located under the vehicle's battery or batteries, causing a controlled temperature rise. This directed heat brings the battery or batteries to an optimal temperature before recharging, thus improving the energy efficiency of the charging process and preserves the longevity of electrochemical cells.

[0146] Preferably, parking spaces incorporating this system can be associated with electric charging stations. The system may further include intelligent sensors, for example pressure or infrared sensors, which detect the presence of a vehicle and automatically activate the heating only when necessary, thus optimizing overall energy consumption.

[0147] Another object of the invention is an electric vehicle charging station comprising the conductive bituminous composition according to the invention and / or the system described above. Such a station offers both charging capacity and an integrated preheating system, improving user comfort, the safety of the charging process, and the durability of the equipment.

Claims

Demands

1. Bituminous composition comprising at least a bitumen base and an electrically conductive filler selected from carbon nanoparticles.

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

4. Bituminous composition according to any one of claims 1 to 3, wherein the carbon nanoparticles have a specific surface area BET of less than 200 m2 / g, preferably between 10 and 100 m2 / g, preferably further between 20 and 80 m2 / g.

5. Bituminous composition according to any one of claims 1 to 3, wherein the carbon nanoparticles have a specific surface area BET greater than 200 m2 / g, preferably between 500 and 3000 m2 / g, preferably further between 1000 and 1500 m2 / g.

6. Bituminous composition 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. A bituminous composition 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 composition according to any one of the preceding claims, having a void percentage of less than 15%, preferably less than 10%, preferably still less than 8%.

9. Bituminous composition according to any one of claims 1 to 8, which is an asphalt, further comprising mineral and / or synthetic fillers having a size less than or equal to 50 pm, preferably less than or equal to 10 pm.

10. Bituminous composition according to any one of claims 1 to 8, which is a bituminous coating, further comprising aggregates, preferably the aggregates comprising gravel, sand and mineral and / or synthetic fillers.

11. Bituminous composition according to any one of the preceding claims, comprising between 0.1% and 96% by weight of electrically conductive filler relative to the total weight of the bituminous composition.

12. Bituminous composition 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.

13. A method for preparing a bituminous composition according to any one of the preceding claims comprising at least one step of incorporating the electrically conductive filler into a bitumen base.

14. Infrastructure system, such as a pavement system or waterproofing membrane, preferably intended for parking and / or charging electric vehicles, comprising at least: - a bituminous composition according to any one of claims 1 to 12; - metallic wires and / or strips, preferably copper and / or aluminum, incorporated in or around said bituminous composition; and - at least two metallic electrodes connected to the metallic wires and / or strips and configured to distribute an electric current in said bituminous composition.

15. Use of a bituminous composition according to any one of claims 1 to 12, or of a system according to claim 14, to prevent the formation of ice on road surfaces, car parks and / or airport runways and / or for the thermal preconditioning of electric vehicle batteries.