Additives for bituminous materials

Abstract

The present invention relates to the use, in a bituminous material comprising a bituminous binder and aggregates, of an additive of formula (I) Ar1−R−Ar2, in which: - Ar1 and Ar2 independently represent an aryl group comprising 6 to 20 carbon atoms, each substituted with at least one hydroxyl group; and - R is an optionally substituted divalent radical comprising 6 to 20 carbon atoms, the radical being interrupted by at least one group selected from ester, hydrazide and amide groups and mixtures thereof, for improving the fatigue strength of the bituminous material.

Description

[0001] DESCRIPTION

[0002] TITLE: Additives for bituminous coatings

[0003] The present invention relates to the field of bituminous coatings, intended in particular for the construction of road structures.

[0004] More specifically, the invention relates to the use of additives in bituminous coating compositions making it possible to improve the mechanical and structural properties of bituminous coatings.

[0005] The road is a main artery for the economy, ensuring the movement of people and goods. However, in recent years, the growth in the transport of goods, particularly by truck, has put the major roads in our network under greater strain. Indeed, the increasing use of roads leads to significant damage to the roadway structures, caused mainly by fatigue due to the repeated passage of heavy goods vehicles. This damage generally results in deformation of the roadway or rutting, or even total deterioration of the roadway requiring its replacement. Therefore, for several years, extensive research has been carried out to improve the formulation of the bituminous mixes constituting the wearing courses of these roads.The formulation of these asphalt mixes requires achieving mechanical behavior targets in line with its use on the road, particularly in terms of workability (PCG), water sensitivity (ITSR), rutting, mechanical modulus and fatigue resistance. However, some of these properties are often anti-synergistic, such as mechanical modulus and fatigue resistance, requiring a compromise to be reached depending on the specificity of the application and the environment in which the material is used.

[0006] Various costly solutions have been proposed, such as the use of different grades of bitumen in bituminous binder compositions or the use of a bitumen-polymer composition in bituminous binder compositions. However, these different solutions do not allow the bituminous mix to maintain good rigidity and good fatigue resistance.

[0007] There is therefore a need to provide bituminous mixes with improved mechanical and fatigue resistance properties. There is also a need to provide bituminous mix compositions having improved durability and improved rutting resistance. The present invention relates to the use in a bituminous mix, comprising a bituminous binder and aggregates, of an additive of formula (I):

[0008] Ari-R-Ar2(I) in which:

[0009] - An and Ar2 represent independently of each other an aryl group of 6 to 20 carbon atoms, each substituted by at least one hydroxyl group; and

[0010] - R is an optionally substituted divalent radical, comprising 6 to 20 carbon atoms, said radical being interrupted by at least one group chosen from ester, hydrazide, amide groups, and their mixtures, to improve the fatigue resistance of said bituminous coating.

[0011] The inventors have surprisingly discovered that it is possible to jointly improve the fatigue resistance and the mechanical properties of a bituminous mix by integrating an additive of formula (I). The inventors have also discovered that the use of this additive in the bituminous binder composition used for the preparation of the bituminous mix similarly makes it possible to improve the water resistance of the bituminous mix as well as its resistance to rutting. Thus, the inventors have discovered that it is possible to synergistically improve certain properties of the bituminous mix known in the prior art to be anti-synergistic.

[0012] By "bituminous mix" is meant a mixture of a bituminous binder with aggregates and possibly mineral and / or synthetic fillers. The bituminous mix according to the invention comprises a bituminous binder and possibly mineral and / or synthetic fillers, preferably chosen from fines, sand, gravel and recycled millings.

[0013] Bituminous mixes are used as materials for the construction and maintenance of road surfaces and their coverings, as well as for carrying out all road works. Examples include surface dressings, hot mixes, cold mixes, cold-poured mixes, emulsified gravel, base, bonding, tack and surface courses, and other combinations of a bituminous binder and road aggregate with specific properties, such as anti-rutting layers, draining mixes, or asphalts (a mixture of a bituminous binder and sand-type aggregates). Aggregates are mineral and / or synthetic aggregates, particularly recycled millings, with dimensions greater than 2 mm, preferably between 2 mm and 20 mm.

[0014] Preferably, the bituminous coatings according to the invention comprise aggregates and / or mineral and / or synthetic fillers in a content ranging from 60% by mass to 99% by mass relative to the total mass of the bituminous coating, preferably ranging from 70% to 98% and even more preferably ranging from 85% to 95%. According to a preferred embodiment of the invention, the bituminous coatings comprise aggregates and / or mineral and / or synthetic fillers in a content ranging from 92% to 95% by mass relative to the total mass of the bituminous coating.

[0015] Additive of formula (I)

[0016] As indicated above, the present invention relates to an additive of formula (I) as defined above for improving the fatigue resistance of said bituminous coating.

[0017] The term "aryl group" means monocyclic, bicyclic or tricyclic aromatic hydrocarbon compounds containing from 6 to 20 carbon atoms. Examples include phenyl and naphthyl groups.

[0018] Preferably, in formula (I), the groups An and An are aryl groups comprising from 6 to 10 carbon atoms, and preferentially are phenyl groups.

[0019] According to the invention, the aryl groups are substituted by at least one hydroxyl group, or even several hydroxyl groups.

[0020] According to a preferred embodiment, at least one of the groups An and / or An is a phenyl group, preferably An and An are phenyl groups.

[0021] According to this embodiment, the R group is preferably in the para position relative to a hydroxyl group of An and / or An.

[0022] According to one embodiment, the groups An and An are phenyl groups which may be substituted by one or more alkyl groups, preferably in one or more ortho positions relative to the hydroxyl group(s) of An and / or An.

[0023] By “alkyl” group is meant a linear or branched aliphatic hydrocarbon group comprising, unless otherwise stated, from 1 to 20, preferably from 1 to 12, for example from 1 to 10 carbon atoms. Examples include methyl, ethyl, n-propyl, butyl, isobutyl, tert-butyl, pentyl or n-hexyl groups.

[0024] Preferably, the groups An and / or An are phenyl groups substituted by at least one alkyl group of 1 to 10 carbon atoms, preferably in one or more ortho positions relative to the hydroxyl group(s).

[0025] Preferably, the groups An and An are 3,5-dialkyl-4-hydroxyphenyl groups, preferably 3,5-di-tert-butyl-4-hydroxyphenyl groups.

[0026] Preferably, the divalent radical R has the following general formula (II): in which:

[0027] -Ri is a C1-C4 alkylene group;

[0028] -R2 represents a single bond or a C1-C10 alkylene group, optionally substituted;

[0029] -Yi and Y2 independently represent either -XC(=O)- or -C(=O)-X-; and

[0030] -X represents an NH group or an oxygen atom.

[0031] Advantageously, the An and An groups bind to the R radical at the Ri groups.

[0032] For the purposes of the invention, the term “alkylene” group means a bivalent aliphatic hydrocarbon group, optionally substituted, considered to be derived from an alkene by opening the double bond or from an alkane by elimination of two hydrogen atoms from different carbon atoms.

[0033] Preferably, in formula (II), the group Ri is chosen from methylene (-CH2-), ethylene (-CH2-CH2-), propylene (-CH2-CH(CH3)- or (- CH2-CH2-CH2-)), or butyl ethylene (-CH2-CH(C4H9)-) groups.

[0034] Preferably, Ri is an ethylene group.

[0035] Preferably, R2 represents a single bond or an n-hexyl group.

[0036] According to one embodiment, the R2 group is substituted by one or more substituents chosen from alkyl, alkaryl and heteroaryl groups.

[0037] By “alkaryl” or “arylalkyl” group is meant a linear or branched hydrocarbon group, comprising, unless otherwise stated, at least one aryl group as defined above.

[0038] By "heteroaryl" group is meant a monocyclic, bicyclic or tricyclic aromatic compound comprising from 4 to 20 carbon atoms and at least one heteroatom chosen from the group consisting of nitrogen, phosphorus, oxygen and sulfur. By way of example, mention may in particular be made of the pyridine, pyrrole, furan, thiophene, imidazole, furazan, oxazole, oxadiazole, oxatriazole, isoxazole, thiazole, isothiazole, pyrazole, triazole or tetrazole groups.

[0039] According to one embodiment, the group R2 is substituted by a group An and / or An. The groups An and An may be identical or different.

[0040] According to a preferred embodiment of the invention, the group R has the following general formula (III): in which Ri is a C1-C4 alkylene group.

[0041] The An and An groups are linked to the R radical at the level of the Ri groups.

[0042] Advantageously, the additive is 2',3-bis[(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl)]propionohydrazide.

[0043] Bituminous binder

[0044] The additive according to the invention is present in the bituminous binder composition used for the preparation of the bituminous coating.

[0045] For the purposes of the invention, the term “bituminous binder” means any bituminous composition used to prepare, in association with aggregates or fillers, bituminous coatings.

[0046] Preferably, the additive is present in the bituminous binder composition used for the preparation of the bituminous mix in a content ranging from 0.01% by mass to 2.5% by mass, preferably ranging from 0.1% to 2%, preferably ranging from 0.5% to 1%, and even more preferably from 0.6% to 0.9% relative to the total mass of bituminous binder.

[0047] According to a preferred embodiment, the bituminous binder composition used for the preparation of the bituminous coating comprises 0.9% by mass of the additive according to the invention relative to the total mass of the bituminous coating.

[0048] By “bituminous binder” we also mean a bituminous composition comprising at least one bitumen base, preferably at least one elastomer and possibly one or more other additive(s).

[0049] The bitumen(s) used to prepare the bituminous binder according to the invention are called “bitumen base”.

[0050] Among the bitumens that can be used according to the invention, mention may firstly be made of bitumens of natural origin, those contained in deposits of natural bitumen, natural asphalt or oil sands and bitumens originating from the refining of crude oil. In the context of the invention, the bitumen(s) used are advantageously chosen from bitumens originating from the refining of crude oil, in particular bitumens containing asphaltenes or pitches. The bitumens can be obtained by conventional processes for the manufacture of bitumens in refineries, in particular by direct distillation and / or vacuum distillation of oil. These bitumens can optionally be visbroken and / or deasphalted and / or rectified in air. It is common practice to carry out vacuum distillation of atmospheric residues originating from the atmospheric distillation of crude oil.This manufacturing process therefore corresponds to the succession of atmospheric distillation and vacuum distillation, the feedstock feeding the vacuum distillation corresponding to the atmospheric residues. These vacuum residues from the vacuum distillation tower can also be used as bitumens. It is also common to inject air into a feedstock usually composed of distillates and heavy products from the vacuum distillation of atmospheric residues from the distillation of oil. This process makes it possible to obtain a blown, or semi-blown, or oxidized, or air-rectified, or partially air-rectified bitumen.

[0051] Among the bitumens that can be used according to the invention, recycling bitumens can also be mentioned.

[0052] Bitumens can be hard grade bitumens (such as grades 10 / 20 and 20 / 30) or soft grade bitumens (such as grade 160 / 220) as defined by EN 12591.

[0053] The invention is particularly suitable for cases where the bitumen base consists of a hard grade bitumen or a mixture of hard grade bitumens, in particular chosen from bitumens of grade 35 / 50, 20 / 30 and 10 / 20.

[0054] Preferably, the bitumen bases used in the context of the invention have a penetrability, measured at 25°C according to standard EN 1426, of 5 to 330 1 / 10 mm, preferably between 10 and 220 1 / 10 mm, more preferably from 10 to 120 1 / 10 mm. In a well-known manner, the measurement known as “needle penetrability” is carried out by means of a standardized test NF EN 1426 at 25°C (P25). This penetrability characteristic is expressed in tenths of a millimeter (dmm or 1 / 10 mm). The needle penetrability, measured at 25°C, according to the standardized test NF EN 1426, represents the measurement of the penetration into a sample of bitumen, after a time of 5 seconds, of a needle whose weight with its support is 100 g.

[0055] Advantageously, the bituminous binder composition may comprise one or more polymer(s), in particular one or more elastomer(s).

[0056] The elastomer is not particularly limited provided that it exhibits the qualities required for coating compositions. Such elastomers are well known in the art and are generally rubbery polymers. In a preferred embodiment, the elastomer comprises styrene butadiene styrene (SBS), hydrogenated SBS, styrene isoprene styrene (SIS), styrene ethylene butadiene styrene (SEBS) and / or polyisobutadiene (PIB).

[0057] According to one embodiment, the bituminous binder composition according to the invention further comprises one or more additional additive(s), different from the additive of formula (I) mentioned above.

[0058] These additional additives are known to those skilled in the art. For example, the following additives may be mentioned in particular: a) adhesive dopes, used to improve the mutual affinity between the binder and the aggregates and ensure their durability. These are, for example, nitrogenous surfactant compounds derived from fatty acids such as alkylamine derivatives, alkylpolyamine derivatives, alkylamidopolyamine derivatives and quaternary ammonium salt derivatives, taken alone or in a mixture.

[0059] Preferably, the adhesive dopes are present between 0.05% and 0.5% by weight relative to the total weight of the bituminous binder composition.

[0060] For example, in a specific embodiment, between 0.05% and 0.5% of amine, preferably between 0.1% and 0.3% of amine, will be added by weight relative to the total weight of the bituminous binder composition. b) waxes of animal or vegetable origin or hydrocarbon waxes, in particular long-chain hydrocarbon waxes, for example polyethylene waxes or paraffins, optionally oxidized. Amide waxes, such as ethylene bis(stearamide), may also be added. c) paraffins having chain lengths of 30 to 120 carbon atoms (C30 to C120). The paraffins are chosen 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,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 fatty substances or hydrocarbon oils of petroleum origin. The 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 in the form of methyl ester. e) resins of vegetable origin, such as rosins. f) anti-foam additives, in particular (but not limited to) chosen from 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) selected from the group consisting of amines, succinimides, alkenylsuccinimides, polyalkylamines, polyalkylpolyamines,polyetheramines and imidazolines. h) slip agents or anti-wear agents, in particular (but not limited to) selected from the group consisting of fatty acids and their ester or amide derivatives, in particular glyceryl monooleate, and mono- and polycyclic carboxylic acid derivatives. i) crystallization modifying additives, paraffin deposition inhibiting additives, pour point lowering additives; 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; amidated maleic anhydride / alkyl (meth)acrylate copolymers obtainable by reacting a maleic anhydride / alkyl (meth)acrylate copolymer and an alkylamine or polyalkylamine having a hydrocarbon chain of 4 to 30 carbon atoms, preferably 12 to 24 carbon atoms; amidated α-olefin / maleic anhydride copolymers obtainable by reaction of an α-olefin / maleic anhydride copolymer and an alkylamine or polyalkylamine, the α-olefin being able to be chosen 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 from 12 to 24 carbon atoms. j) antioxidants, for example of hindered phenolic type or of amino type, of alkylated para-phenylenediamine type. k) metal passivators. l) acidity neutralizers. m) additives for lowering the mixing temperature of asphalts and coated materials, those for improving the adhesion of bituminous binders to fillers and aggregates, such as, for example, polyisobutylene succinimides. n) acids, such as polyphosphoric acid, or diacids, in particular fatty diacids. The additives are used in quantities well known to those skilled in the art, depending on the nature of the additive, the bituminous base and the expected properties.,

[0061] Preferably, the bituminous binder composition used in the present invention is a bagged bituminous binder.

[0062] Preferably, the bituminous coating comprises a bituminous binder in a content ranging from 0.1% by mass to 10% by mass relative to the total mass of the bituminous coating, preferably ranging from 2% to 8% and even more preferably ranging from 3% to 6%.

[0063] Use

[0064] The present invention also relates to the use of at least one additive of formula (I) in a bituminous coating to improve the fatigue resistance of said bituminous coating.

[0065] By "fatigue phenomenon" of a bituminous coating, we mean a phenomenon which is characterized by the rupture of the bituminous coating after repeated application of a large number of mechanical stresses whose amplitude is less than the instantaneous breaking strength of the bituminous coating.

[0066] For the purposes of the invention, the term "mechanical stresses" means tensile and compressive stresses applied to the bituminous coating, such as the passage of a heavy vehicle on the road.

[0067] These repeated stresses on the base of the layers of a roadway, under the effect of the passage of vehicles, particularly heavy vehicles, can cause damage which accumulates and can cause deformation, deterioration, cracking or rupture of the bituminous coating through fatigue.

[0068] The determination of the fatigue resistance of a bituminous coating is determined according to standard NF EN 12697-24. Generally, the fatigue resistance of a bituminous coating is measured by two-point bending fatigue tests at constant deflection amplitude on a trapezoidal specimen as defined in standard NF EN 12697-24.

[0069] Advantageously, the use of an additive of formula (I) according to the invention in a bituminous coating makes it possible to improve the mechanical modulus of said bituminous coating.

[0070] By "mechanical modulus" we mean a physical quantity allowing the mechanical behavior of the bituminous coating to be assessed, more precisely, it is an indicator of the degree of cohesion within the structure of the bituminous coating and is translated by a complex modulus |E*|. The mechanical modulus is generally measured by rigidity modulus tests by direct tension or by bending on a trapezoidal specimen. These tests are described in standard NF EN 12697-26.

[0071] Advantageously, the use of an additive of formula (I) according to the invention in a bituminous coating makes it possible both to improve the fatigue resistance of the bituminous coating and also to improve the mechanical modulus of said bituminous coating.

[0072] Preferably, the bituminous coating comprising the additive according to the invention has a complex modulus |E*|, measured at 10°C according to the method defined in standard NF EN 12697-26, ranging from 15,000 MPa to 22,000 MPa, preferably from 16,000 MPa to 21,000 MPa.

[0073] Preferably, the bituminous coating comprising the additive according to the invention has a complex modulus |E*|, measured at 15°C according to the method defined in standard NF EN 12697-26, ranging from 15,000 MPa to 22,000 MPa, preferably from 16,000 MPa to 18,000 MPa.

[0074] According to one embodiment, the use of an additive of formula (I) according to the invention in a bituminous coating makes it possible to improve the water resistance of said bituminous coating.

[0075] In other words, the use of the additive according to the invention in a bituminous coating makes it possible to improve the performance of the coating when it is in contact with water.

[0076] Indeed, it is known from the state of the art that the sensitivity of bituminous coatings to water is generally associated with a loss of strength and durability. Without wanting to enter into any theory, the infiltration of water into the coating limits the cohesion between the bituminous binder and the aggregates or fillers making up the coating. The limitation of the binder-aggregate interaction leads to insufficient adhesion which results in rapid deterioration of the coating under the influence of mechanical stresses such as, for example, the load of road traffic.

[0077] Advantageously, the use of the additive according to the invention in a bituminous coating makes it possible to limit the infiltration of water into the bituminous coating and therefore improve its durability.

[0078] The water resistance of a bituminous coating can be measured using various methods known to those skilled in the art. One example is the compression method, called the "Duriez test", which is defined by standard NF EN 12697-12.

[0079] According to one embodiment, the use of the additive according to the invention allows an improvement in the water resistance of the bituminous coating measured according to the method defined in standard NF EN 12697-12, compared to the same bituminous coating not comprising said additive, ranging from 1% to 20%, preferably from 5% to 15%.

[0080] According to one embodiment, the use of an additive of formula (I) according to the invention in a bituminous coating makes it possible to improve the resistance to rutting of said bituminous coating.

[0081] By "rutting" we mean the process of longitudinal deformation of the road surface characterized by compaction of the road surface which occurs under the repeated passage of wheels.

[0082] More specifically, repeated traction at the base of the layers of a road surface, namely the bituminous coating, under the effect of the passage of heavy vehicles, causes "micro" damage which accumulates and can lead to deformation of the bituminous coating.

[0083] In other words, the use of the additive according to the invention makes it possible to improve the resistance to deformation of the bituminous coating under the effect of repeated passage of heavy vehicles.

[0084] The resistance to rutting was assessed using an “LPC rut” traffic simulator defined in standard NF EN 12697-22.

[0085] These tests measure the depth of the rut after 30,000 passages of heavy vehicles. The average standard value of the depth must be less than 10%.

[0086] Preferably, the bituminous coating comprising the additive according to the invention has a rut depth, measured according to the method defined in standard NF EN 12697-24, ranging from 0.1% to 3%, preferably from 0.2% to 2%, and even more preferably from 0.5% to 1.5%.

[0087] According to one embodiment, the use of the additive according to the invention allows an improvement in the rutting of the bituminous coating measured according to the method defined in standard NF EN 12697-24 compared to the same bituminous coating not comprising said additive, ranging from 1% to 5%, preferably from 1.5% to 3%. EXAMPLES

[0088] Evaluation of bituminous coating compositions

[0089] In the following examples, the bituminous compositions are evaluated by:

[0090] - handling measurements using the “PCG” gyratory shear press, according to standard NF EN 12697-31;

[0091] - compression and water resistance tests using the “Duriez” test, according to standard NF 12697-12;

[0092] - rutting tests measured using a “LPC rutting machine” traffic simulator, according to standard NF EN 12697-22. These tests measure the depth of the rut after 30,000 passages of heavy vehicles, the bench being at a temperature of 60°C.

[0093] - fatigue tests measured by two-point bending tests at constant deflection amplitude on trapezoidal specimens, according to standard NF EN 12697-24; and

[0094] -rigidity modulus tests by direct traction or by bending on trapezoidal specimen according to standard NF 12697-26.

[0095] Raw materials

[0096] The examples were made with the following raw materials:

[0097] Loads and Aggregates: The granular sections used for these studies are as follows: 6 / 10 Diorite Laubreçais gravel, 2 / 6 Diorite Laubreçais gravel and 0 / 2 Diorite Laubreçais sand

[0098] The filler is a limestone filler.

[0099] Bituminous binders and bitumen bases: The various bituminous bases and bituminous binders used to prepare bituminous coatings are made from the following raw materials:

[0100] - Pure Bitumen 35 / 50 from the Total Feyzin refinery (69), used for this study, has a penetrability at 25°C of 45 1 / 10 mm and a TBA of 52.8°C commercially available from Total Energies

[0101] - Bituminous binder I (comparative): Bituminous binder I is a bagged bituminous binder (bags of pure bitumen pellets) produced using an extrusion / granulation process coupled with bagging. It is equivalent to a 35 / 50 grade talcated at 1% by mass.

[0102] - Bituminous binder II with the additive according to the invention: Bituminous binder II is a bagged bituminous binder produced from a pelletization process coupled with bagging, it has a mass content of additive according to the invention of 0.9% by mass relative to the total mass of the bituminous binder. Elastomer: The complementary elastomer used is an SBS polymer marketed by Eiffage under the name Eiffaprene©. It makes it possible to obtain a polymer bitumen directly at the time of manufacturing the asphalt by adding pellets in dry-batch mode.

[0103] Additive according to the invention: 2',3-bis[(3-[3,5-di-ferf-butyl-4-hydroxyphenyl]propionyl)] propionohydrazide

[0104] Preparation of compositions

[0105] The compositions according to the invention C1 and C2, and the comparative compositions C3, C4, C5 and C6 are prepared according to the following protocol:

[0106] The bituminous binder (or pure bitumen base) is first heated to 160°C in an oven, then transferred to a 3L reactor in which it is heated for 1 hour at 180°C. The fillers and aggregates are then added to the mixture to prepare the asphalt.

[0107] The details of the compositions are given in Table 1 below. The contents are given by mass, relative to the total mass of the bituminous coating.

[0108] [Table 1]

[0109] Composition C1 according to the invention is a composition in which the bitumen is substituted in mass by a bituminous binder II comprising the additive according to the invention.

[0110] Composition C2 according to the invention is a composition in which the bitumen is substituted in mass by a bituminous binder II comprising the additive according to the invention and an elastomer. Comparative composition C3 comprises a pure bitumen base 35 / 50 (reference 35 / 50).

[0111] Comparative composition C4 is a composition in which the bitumen is substituted in mass by a bituminous binder I.

[0112] Comparative composition C5 is a composition comprising a 35 / 50 pure bitumen base and an elastomer.

[0113] Comparative composition C6 is a composition in which the bitumen is substituted in mass by a bituminous binder I and an elastomer.

[0114] Properties of bituminous coatings

[0115] The properties of compositions C1-C6 were evaluated according to the protocols defined above. The results are summarized in Table 2 below.

[0116] [Table 2]

[0117] Composition C1 shows an improvement in most of the mechanical characteristics compared to comparative composition C3 comprising a 35 / 50 pure bitumen base and comparative composition C4 comprising a conventional bituminous binder without the additive according to the invention. An improvement is observed for composition C1 in the modulus / fatigue pair, which are usually antagonistic properties. There is no deterioration in workability.

[0118] Furthermore, composition C2 according to the invention demonstrates that the addition of an elastomer allows an improvement in most of the mechanical characteristics compared to comparative composition C5 comprising a 35 / 50 pure bitumen base and comparative composition C6 comprising a conventional bituminous binder without the additive according to the invention. In addition, the workability of the mixture is not affected.

Claims

CLAIMS 1. Use, in a bituminous coating, comprising a bituminous binder and aggregates, of an additive of formula (I) An-R-Ar2(I) in which: - An and Ar2 represent independently of each other an aryl group comprising from 6 to 20 carbon atoms, each substituted by at least one hydroxyl group; and - R is a divalent radical, optionally substituted, comprising from 6 to 20 carbon atoms, said radical being interrupted by at least one group chosen from ester, hydrazide, amide groups, and their mixtures, to improve the fatigue resistance of said bituminous coating.

2. Use according to claim 1, in which, in formula (I), An and Ar2 are phenyl groups.

3. Use according to claim 1 or 2, in which An and Ar2 are phenyl groups substituted by at least one alkyl group of 1 to 10 carbon atoms, preferably in the ortho position relative to the hydroxyl group(s).

4. Use according to claim 2 or 3, in which the R group is in the para position relative to a hydroxyl group of An and / or Ar2.

5. Use according to any one of the preceding claims, in which An and Ar2 are 3,5-dialkyl-4-hydroxyphenyl groups, preferably 3,5-di-tert-butyl-4-hydroxyphenyl groups.

6. Use according to any one of the preceding claims, wherein the additive is 2',3-bis[(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl)]propiono-hydrazide.

7. Use according to any one of the preceding claims, in which the content of additive of formula (I) is from 0.01% by mass to 2.5% by mass. mass, preferably from 0.1% to 2% and preferably from 0.5% to 1%, and even more preferably from 0.6% to 0.9% relative to the total mass of bituminous binder.

8. Use according to any one of the preceding claims, in which the bituminous coating comprises mineral and / or synthetic fillers.

9. Use of an additive of formula (I) in a bituminous coating according to any one of the preceding claims, to improve the mechanical modulus of said coating.

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