BITUMINOUS COMPOSITIONS WITH A HIGH DECONGESTATION TEMPERATURE

Description

[0001] The present invention relates to the technical field of bitumens. More specifically, it relates to bituminous compositions having improved aging properties. The invention also relates to the methods for preparing such compositions, as well as their uses in the road and industrial fields.

[0002] Improving the properties of bituminous compositions has already been the subject of numerous studies. In particular, during their use, bituminous compositions are subject to numerous stresses, in particular to variations in temperature and weather conditions. Solutions are therefore sought to improve their resistance to aging and damage due to humidity, oxygen diffusion (oxidation) or UV radiation, in particular. It has been proposed in the prior art to introduce nanoclays to improve the thermal or mechanical properties of bitumens and their resistance to aging: Z. You et al. Construction and Building Materials 2011, 25, 1072-1078 use unmodified montmorillonite or montmorillonite modified with an organic structural modifier: , T not being defined. The properties of the compositions mentioned in this article were only evaluated directly after mixing the clays into the bitumen. No long-term aging studies were carried out by the authors.

[0003] In more recent work, Ashish et al. (Construction and Building Materials 2016, 113, 341-350) used Cloisite ®< 30B, an organomodified clay with methyl di(2-hydroxyethyl) (hydrogenated soot) ammonium, in bituminous binders for asphalt. This work demonstrates the benefit of this type of clay for improving the initial mechanical properties of asphalt.

[0004] Within the framework of the invention, the inventors propose to include in bituminous compositions, particular clays, making it possible to achieve particularly satisfactory properties of resistance to aging, particularly in the long term.

[0005] In this context, the invention relates to a bituminous composition comprising: a bitumen base, organically modified clay particles distributed in the bitumen base, said organically modified clay particles having a degradation start temperature in air greater than or equal to 175°C, said bituminous composition being as defined in claim 1.

[0006] The invention also relates to a process for preparing a bituminous composition according to the invention comprising mixing the bitumen base and organically modified clay particles, at a temperature belonging to the range from 100 to 200°C, preferably to the range from 120 to 180°C, and preferentially to the range from 140 to 180°C.

[0007] According to another of its aspects, the invention relates to the use of organically modified clay particles having a degradation start temperature in air greater than or equal to 175°C, to improve the long-term aging resistance of a bituminous composition, as defined in claim 13.

[0008] The bituminous compositions according to the invention find various applications. Also, the invention also relates to: the use of a bituminous composition according to the invention, for preparing a waterproofing coating, a membrane or an impregnation layer; bituminous binders comprising a bituminous composition according to the invention; bituminous coatings comprising a bituminous binder according to the invention, aggregates, and optionally mineral and / or synthetic fillers; as well as the use of a bituminous binder according to the invention, for preparing a surface coating, a hot mix, a cold mix, a cold-poured mix, an emulsion gravel or a wearing course, said binder being associated with aggregates and / or recycled millings.

[0009] The invention is described in more detail in the following description. Bitumen

[0010] The invention relates to bitumen compositions modified by the addition of at least one additive or adjuvant, also called bituminous compositions. These may comprise one or more bitumens. The bitumen or bitumens present are called "bitumen base" and constitute(s) the majority of the composition, i.e. generally represent(s) at least 75% by mass of the total mass of the bituminous composition, and preferably at least 94%, or even at least 96% and even more preferably at least 97% by mass of the total mass of the bituminous composition. 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 manufacturing 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 originating 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 petroleum distillation. This process makes it possible to obtain a blown, or semi-blown, or oxidized, or air-rectified or partially air-rectified bitumen. 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 manufacturing bituminous compositions, the operation is carried out at manufacturing temperatures of between 100°C and 200°C, preferably between 140°C and 200°C, and with stirring for a period of at least 10 minutes, preferably between 30 minutes and 10 hours, more preferably between 1 hour and 6 hours.Manufacturing temperature refers to the heating temperature of the bitumen(s) before mixing with additives, as well as the mixing temperature. The heating temperature and duration vary depending on 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 bitumen mixture. This operation can be carried out in the presence of an oxidation catalyst, for example phosphoric acid. Generally, blowing is carried out at high temperatures, in the order of 200 to 300°C, for relatively long periods of time, typically between 30 minutes and 2 hours, continuously or in batches. The blowing time and temperature are adjusted according to the properties targeted for the blown bitumen and the quality of the starting bitumen.

[0011] Among the bitumens that can be used according to the invention, recycling bitumens can also be mentioned.

[0012] 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.

[0013] 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.

[0014] The bitumen bases that can be used in the context of the invention preferably 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 so-called “needle penetrability” measurement 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. Clay

[0015] Within the scope of the invention, the bituminous compositions comprise organically modified clay particles, as an additive.

[0016] The clay can be chosen from bentonite and montmorillonite. Bentonite is known to contain montmorillonite (usually around 90%) and other components. Montmorillonite is a purified bentonite.

[0017] According to an essential characteristic of the invention, the organically modified clay particles have a degradation start temperature in air greater than or equal to 175°C. The degradation start temperature of the organically modified clay particles is, in particular, measured in the context of the invention, using a thermogravimetric analyzer, by placing the organically modified clay particles under a flow rate of 60 mL / min of air containing 21% oxygen. The temperature is increased by 10°C / min. The value of the degradation start temperature is obtained by plotting the derivative of the mass loss as a function of temperature (% / °C), as illustrated Figure 1 .The degradation start temperature corresponds to the lowest temperature, from which the mass loss derivative is equal to = 0.005% / °C. For more details, please refer to the examples that follow.

[0018] In the context of the invention, the organically modified clay particles have, before mixing with the bitumen base, a distance d(001) of at least 2.6 nm, preferably at least 3.2 nm, or even at least 3.5 nm. This distance corresponds to the distance separating the layers constituting the clay particles. The higher the distance d(001), the more stable the clay, for the same organic modifier. In general, the organically modified clay particles will, however, have, before mixing with the bitumen base, a distance d(001) less than or equal to 5 nm, preferably less than or equal to 4 nm. In particular, the organically modified clay particles have, before mixing with the bitumen base, a distance d(001) in a range from 2.6 to 5 nm or from 2.6 to 4 nm or from 3.2 to 5 nm or from 3.2 to 4 nm or from 3.5 to 5 nm or from 3.5 to 4 nm. The distance d(001) can be determined by X-ray diffraction.In particular, X-ray diffraction analysis can be performed using Cu-Kα radiation, over an angular range 2θ from 1 to 10°. The distance d(001) is determined by Bragg's law according to the equation: nλ = 2dsinθ. For more details, please refer to the following examples.

[0019] The clay particles used in the context of the invention can be organically modified by different organic modifiers. The organic modifier used does not comprise an OH function. Preferably, the organic modifier used does not comprise an aromatic group.

[0020] Such organic modifiers are chosen from cations comprising at least one hydrogenated tallow group, and preferably comprising two hydrogenated tallow groups, and in particular quaternary ammonium cations, such as: ∘ methyl di(hydrogenated tallow) ammonium, in English “methyl dihydrogenated tallow ammonium” of formula: with HT = hydrogenated tallow, in French “hydrogenated soot” which corresponds to a mixture of saturated alkyl chains in C14-C18, which can be symbolized by the formula -CH 2 (CH 2 ) 12-16 -CH 3 , the chains in C16-C18 being the most abundant; ∘ dimethyl di(hydrogenated soot) ammonium, in English “dimethyl-dihydrogenated tallow ammonium” of formula: (dimethyl di(hydrogenated soot) ammonium chloride has the CAS number 61789-80-8).

[0021] In the context of the invention, in a particularly advantageous manner, organically modified clay particles having the following characteristics will be used: a degradation start temperature in air greater than or equal to 175°C, a distance d(001) of at least 3.2 nm, preferably at least 3.5 nm, in particular in a range from 3.2 to 5 nm or from 3.5 to 5 nm or from 3.2 to 4 nm or from 3.5 to 4 nm, the clay particles are organically modified with methyl di(hydrogenated soot) ammonium, or preferably with dimethyl di(hydrogenated soot) ammonium.

[0022] Organically modified clays usable in the context of the invention are commercially available. They can also be obtained by cation exchange between sodium or calcium cations initially present in the clay particles and an organic cation, in particular of the quaternary ammonium type, present in organic salts, of the chloride type for example. In particular, the distance d(001) of the clay before addition of the organic modifier and the nature of the organic modifier influences the degradation temperature of the organically modified clay. A distance d(001) of at least 2.6 nm, preferably at least 3.2 nm, or even at least 3.5 nm for the organically modified clay particles, before mixing with the bitumen base, is particularly suitable for clays modified with a cation comprising at least one hydrogenated soot group as previously described.

[0023] In any case, organically modified clay particles usable in the context of the invention are commercially available. As examples, mention may be made of the clays marketed under the references Dellite ®< 67G and Dellite ®< 72T marketed by Laviosa (Italy), under the references Cloisite ®< 5 and Cloisite ®< 93, marketed by BYK (Germany) and under the references Nanomer ®< I31PS marketed by Nanocor (USA).

[0024] The organically modified clay particles used comprise from 20 to 50% by mass, preferably from 30 to 50% by mass of organic modifier, relative to the total mass of the organically modified clay particles.

[0025] According to particular embodiments that can be combined with the previous ones, the organically modified clay particles have an average size d 50 less than or equal to 100 µm, preferably less than or equal to 10 µm. Such clay particles are conventionally called nanoclays. Conventionally, the average size d 50 is defined as follows: 50% by mass of the particle population has a size less than d 50, and can be obtained by analysis under dry laser diffraction. The clays are, in general, platelet-shaped with a thickness much smaller than the dimensions in the plane of the platelet.

[0026] The compositions according to the invention comprise from 0.5 to 6% by mass, in particular from 1 to 4% by mass, and in particular from 1 to 3% by mass, of organically modified clay particles, relative to the total mass of the composition. Bituminous compositions, also called bitumen compositions, according to the invention

[0027] Although it is not excluded that the bitumen compositions according to the invention comprise, in addition to the organically modified clay particles, one or more other additives, in particular chosen from those conventionally used in bituminous compositions, preferably, the bitumen base and the organically modified clay particles represent at least 90% by mass, preferably at least 95% by mass, or even 100% by mass of the total mass of the bituminous composition.

[0028] Organically modified clay particles are dispersed in the bituminous composition, and therefore in the bitumen base.

[0029] In the bituminous compositions according to the invention, the organically modified clay particles may be completely exfoliated. In this case, it is not possible to measure a distance d(001) on the X-ray diffraction spectrum obtained. Nevertheless, in the compositions according to the invention, the bitumen base will, advantageously, be intercalated in the organically modified clay particles. Such a distribution is notably illustrated in the publication by A. Zare-Shabadi et al., Construction and Building Materials 2010, 24, 1239-1244, Figure 1. In such a case, advantageously, the organically modified clay particles have, in the bituminous composition according to the invention, a distance d(001) in the range from 3.6 to 5 nm, preferably in the range from 4 to 5 nm, preferably in the range from 4 to 4.7 nm. This distance is greater than that observed before incorporation of the organically modified clay particles into the bituminous composition.

[0030] The incorporation of the clay particles recommended in the context of the invention makes it possible to improve the resistance to aging of the bituminous compositions obtained, when these are subjected to prolonged oxidation. It has been demonstrated, using rheological tests, that the incorporation into bituminous compositions of organically modified clay particles having a degradation start temperature in air greater than or equal to 175°C led to better resistance to aging, compared with the incorporation of organically modified clay particles having a lower degradation start temperature, and in particular compared with the incorporation of Cloisite ® particles < 30B used in the prior art.

[0031] The examples which follow also demonstrate that the incorporation of organically modified clay particles having a degradation start temperature in air greater than or equal to 175°C makes it possible to obtain long-term resistance to oxidation aging. In particular, the bituminous compositions according to the invention have an oxidation index less than or equal to 120, the oxidation index corresponding to the ratio between the complex modulus obtained by rheology (dynamic shear rheometer, at a frequency of 1 Hz and at a temperature of 70°C) after 96 hours of oxidation in a pressure aging vessel (PAV) at 100°C and 21 MPa of air pressure, to the complex modulus obtained before oxidation.

[0032] This oxidation index is therefore based on the complex modulus obtained by rheology and is calculated by making the ratio of the complex modulus of the bituminous composition containing the clays after oxidation to the complex modulus of this same composition before oxidation. This is translated by the following formula: Indice d ′ oxydation rhéologique = G * après oxydation / G * avant oxydation

[0033] This index can be calculated for an angular frequency of 1 Hz and at a temperature of 70°C, using a dynamic shear rheometer, notably that of the Malvern company, Kinexus Lab + model.

[0034] In other words, within the framework of the invention, the evaluation of bituminous compositions is carried out in two stages: 1) the compositions are aged using a PAV system under 21MPa air pressure and at a temperature of 100°C, for a period of up to 96h, 2) the properties of the compositions are then evaluated, after different aging times using rheology. For this, a measurement carried out with a dynamic shear rheometer, at a frequency of 1Hz and a temperature of 70°C, is used.

[0035] Also, the invention also relates to the use of organically modified clay particles having a degradation onset temperature in air greater than or equal to 175°C, as described in the present invention, to improve the long-term aging of a bituminous composition. Long-term aging can be evaluated by leaving a bituminous composition, for several hours (preferably up to 96h) at 100°C under an air pressure of 21 MPa in a pressure aging vessel. The air contains 21% by volume of oxygen. The properties of the bituminous composition can then be evaluated using a rheological analysis at 70°C and an angular frequency of 1 Hz, with a dynamic shear rheometer. Preparation of bituminous compositions according to the invention

[0036] The bituminous compositions of the invention may be prepared by any method known to those skilled in the art. Generally, these methods include mixing the components and heating the mixture. The bitumen may be heated before mixing. Usually, the bitumen is heated before mixing, and the additive(s) are added to the bitumen without having been heated beforehand. According to a particular embodiment of the invention, a bitumen composition according to the invention is prepared by bringing into contact: the bitumen base, 0.5 to 6% by mass, in particular 1 to 4% by mass, and in particular 1 to 3% by mass of organically modified clay particles, as defined in the context of the invention, possibly other additives.

[0037] The mass percentages are calculated relative to the total mass of the bituminous composition obtained. Conventionally, the mixture of the bitumen base and the organically modified clay particles is carried out at temperatures ranging from 100 to 200°C, preferably from 120 to 180°C, and preferably from 140 to 180°C. Advantageously, the mixture is carried out at a temperature greater than or equal to 150°C, preferably greater than or equal to 160°C.

[0038] Such a mixture is carried out with stirring, in particular, for a period of 5 minutes to 10 hours, preferably 10 minutes to 3 hours, preferably 10 to 90 minutes, and even more preferably 20 to 90 minutes. The mixture can be carried out by means of stirring producing high shear or stirring producing low shear. In particular, the mixture is carried out with stirring of 1000 to 10000 rpm, preferably 2000 to 5000 rpm, and preferably 2500 to 4000 rpm. Stirring is carried out so as to facilitate the dispersion and good distribution of the clay in the bitumen base. A person skilled in the art will adjust the time and power of the stirring, to obtain exfoliation of the organically modified clay particles or intercalation with the bitumen base, depending on what is desired. Use and implementation of the bitumen compositions according to the invention

[0039] Various uses of the bitumen compositions obtained according to the invention are envisaged. In particular, the bitumen compositions according to the invention can be used for the preparation of a bituminous binder. The bituminous binder according to the invention can in turn be used to prepare a combination with aggregates, in particular road aggregates. With regard to road applications, the invention relates in particular to bituminous coatings as materials for the construction and maintenance of road surfaces and their surfacing, as well as for carrying out all road works.

[0040] By bituminous mix is ​​meant a mixture of a bituminous binder with aggregates and possibly mineral and / or synthetic fillers. The bituminous mix comprises a bituminous binder as described in the context of the invention, and possibly mineral and / or synthetic fillers, preferably chosen from fines, sand, gravel and recycled millings. The aggregates are mineral and / or synthetic aggregates, in particular recycled millings, with dimensions greater than 2 mm, preferably between 2 mm and 20 mm.

[0041] The bituminous binder according to the invention can advantageously be used to prepare a surface coating, a hot mix, a cold mix, a cold-poured mix or an emulsion gravel. With regard to road applications, the invention also relates to asphalts as materials for manufacturing and covering pavements.

[0042] Asphalt is understood to mean a mixture of bituminous binder with mineral and / or synthetic fillers. An asphalt comprises a bituminous binder as described in the context of the invention and mineral fillers such as fines, sand or gravel and / or synthetic fillers. The mineral fillers consist of fines (particles with dimensions less than 0.063 mm), sand (particles with dimensions between 0.063 mm and 2 mm) and possibly gravel (particles with dimensions greater than 2 mm, preferably between 2 mm and 4 mm). Asphalts have 100% compaction and are mainly used to manufacture and cover sidewalks, whereas asphalts have a compaction of less than 100% and are used to manufacture roads. Unlike asphalts, asphalts are not compacted by roller during their installation.

[0043] Another aspect of the invention relates to the use of a bitumen composition in various industrial applications, in particular for preparing a waterproofing coating, a membrane or an impregnation layer. Industrial applications of the bituminous compositions include the manufacture of waterproofing membranes, noise reduction membranes, insulation membranes, surface coverings, carpet tiles, impregnation layers.

[0044] The following examples, with reference to the attached Figures, illustrate the invention, but are not limiting in nature. There Figure 1 presents the thermogravimetric analysis curve - TGA obtained for Dellite ® clay < 67G. The Figure 2 presents the evolution of the oxidation index (X), as a function of the applied angular frequency (Y=frequency in Hz) for different bituminous compositions. The Figure 3presents the oxidation index obtained as a function of the aging time, for different bituminous compositions according to the invention. Tests carried out 1. Determination of the temperature at which degradation begins

[0045] Device used: Thermogravimetric analyzer: TA Instrument model Q500; The clay particle sample was placed under an air flow containing 21% v / v oxygen (O 2 ) of 60 mL / min; The balance was maintained in a nitrogen atmosphere (flow of 40 mL / min).

[0046] The degradation onset temperature was obtained by thermogravimetric analysis (TGA) measurement with a temperature ramp of 10°C / min. The degradation onset temperature value was obtained by plotting the mass loss derivative as a function of temperature (% / °C). The degradation onset temperature corresponds to the lowest temperature from which the mass loss derivative is equal to = 0.005% / °C, as shown in Figure 1 in the case of Dellite ® clay < 67G. To avoid confusion with water loss, the temperature at which degradation begins was measured on clays that had previously been dried at 110°C for 1 hour (to eliminate any presence of moisture). 2. Measurement of the distance d(001)

[0047] X-ray diffraction analysis was performed using Cu-Kα radiation, with wavelength λ 1.54 Å over an angular range 2θ from 1 to 10°. The distance d(001) is determined by Bragg's law according to the equation: nλ = 2dsinθ 3. Aging tests

[0048] The bituminous compositions were subjected to different aging times using a Pressure Ageing Vessel (PAV) system operating at 100°C and 21MPa air pressure. The aging time ranged from 25h to 96h. A 96h PAV time at 100°C and 21MPa air pressure represents a particularly severe test in terms of bitumen oxidation. 4. Rheological characterizations

[0049] They were carried out using a Malvern dynamic shear rheometer, Kinexus brand, Lab + model. The tests were carried out using 20 mm plane / plane geometers. The results were obtained by performing frequency sweeps in the linear domain at 70°C.

[0050] Two types of characterizations were carried out: A characterization of an oxidation index by varying the angular frequency for bituminous compositions having undergone a 25h oxidation step of PAV at 100°C and 21MPa of air pressure ( Figure 2 ) ; A characterization at a frequency of 1Hz of an oxidation index as a function of the oxidation duration at PAV ( Figure 3 ).

[0051] In both cases, the oxidation index is based on the complex modulus obtained by rheology, it is calculated by making the ratio of the complex modulus of the bituminous composition containing the clays after oxidation, to the complex modulus of this same composition before oxidation. This is translated by the following formula: Preparation of bituminous compositions

[0052] The results presented were obtained under the following conditions: The bitumen used was grade 35 / 50 according to EN 12591; The clay particles are introduced into the already hot bitumen; Mixing temperature: 150°C; Stirring speed: 3600 rpm; Stirring for 30 minutes; The quantity of clay introduced was 6% m / m relative to the total mass of the bituminous composition obtained.

[0053] Various tests were carried out, varying the nature of the clay introduced. The clays tested and their characteristics are presented in the Table 1 hereinafter. The Table 2, for its part, presents the X-ray diffraction data for the bituminous compositions obtained. Table 1 characteristics of the clays tested : No. Example Name of clay Nature 1) clay 2) grouping Tdeg (°C) d(001) (nm) before insertion Average size (a) organic group % m / m in clay Example 1 1) Montmorillonite 178 3,7 micrometric 42% Dellite 67G 2) dimethyl di(hydrogenated soot) ammonium Example 2 1) Montmorillonite 181 2,9 micrometric 34% Dellite 72T 2) dimethyl di(hydrogenated soot) ammonium Example 3 1) Montmorillonite 190 2,7 < 40 µm 35% Cloisite 93 2) methyl di(hydrogenated soot) ammonium Comparison 1 1) Bentonite 170 1,85 micrometric 25% Cloisite 30B 2) methyl di(2-hydroxyethyl) (hydrogenated soot) ammonium Comparison 2 1) montmorillonite 161 1,8 micrometric 22% Nanomer I34TCN 2) methyl di(2-hydroxyethyl) (hydrogenated soot) ammonium Example 4 1) montmorillonite 179 2,2 14 to 18µm in 26% Nanomer I31PS outside the invention 2) propyltriethoxysilane ammonium and octadecylammonium average Comparison 3 147 2,0 Micrometric (90% of particles are smaller than 13µm) 33% Cloisite 10A (a): supplier data Table 2: d(001) of clay in bituminous compositions obtained THE No. Example Trade name of clay d(001) (nm) in bitumen Δ d(001) before mixing and after mixing with bitumen Example 1 4,6 Dellite 67G Δ d(001) = 0.9 Example 2 4,4 Dellite 72T Δ d(001) = 1.5 Example 3 4,2 Cloisite 93 Δ d(001) = 1.5 Comparison 1 Exfoliated so no more d001 because all the layers are separated Cloisite 30B Comparison 2 Exfoliated so no more d001 because all the layers are separated Nanomer I34TCN Example 4 outside the invention 3,9 Nanomer I31PS Δ d(001) = 1.7 Comparison 3 4,4 Cloisite 10A Δ d(001) (nm) = 2.4

[0054] There Figure 2 shows the evolution of the oxidation index (X), as a function of the applied angular frequency (Y=frequency in Hz) for different bituminous compositions. It appears that the compositions according to the invention have the best oxidation index.

[0055] There Figure 3presents the oxidation index obtained as a function of the aging time (aging conditions: 100 °C under an air pressure of 21 MPa) for the bituminous compositions according to the invention comprising the clays Dellite ®< 67G, 72T and Cloisite ®< 93. The oxidation index is greatly reduced compared to bitumen alone (35-50), and this up to 96 hours of aging. In the case of example 4 and comparative example 3, only the GAI after a duration of 96 hours of PAV at 100 °C and 21 MPa of air pressure representing a particularly severe test in terms of oxidation of the bitumen, was evaluated. A test was also carried out with only 3% m / m and not 6% m / m of 67G clay. The compositions according to the invention exhibit much more limited aging at 96 hours, even with the use of only 3% clay.

Claims

1. - A bituminous composition comprising: - a bitumen base, - organically modified clay particles distributed in the bitumen base, characterized in that the organically modified clay particles have a temperature at the beginning of degradation under air greater than or equal to 175°C and are modified with an organic modifier chosen from amongst cations that comprise at least one hydrogenated soot moiety and do not comprise the OH functional group, said organic modifier representing from 20 to 50% by weight of the total weight of the organically modified clay, said organically modified clay particles having, prior to mixing with the bitumen base, a distance d(001) of at least 2.6 nm, said organically modified clay particles representing from 0.5 to 6% by weight with respect to the total weight of the bituminous composition.

2. - The bituminous composition according to claim 1, characterized in that the organically modified clay particles have, prior to mixing with the bitumen base, a distance d(001) of at least 3.2 nm, or even at least 3.5 nm.

3. - The bituminous composition according to claim 1 or 2, characterized in that the clay particles are modified with an organic modifier chosen from amongst the cations comprising two hydrogenated soot moieties.

4. - The bituminous composition according to claim 3, characterized in that the clay particles are modified with methyl di(hydrogenated soot) ammonium or preferably dimethyl di(hydrogenated soot) ammonium.

5. - The bituminous composition according to one of claims 1 to 4, characterized in that same comprises from 1 to 4% by weight, and in particular from 1 to 3% by weight of organically modified clay particles, with respect to the total weight of the bituminous composition.

6. - The bituminous composition according to one of claims 1 to 5, characterized in that the organic modifier of the organically modified clay particles represents from 30 to 50% by weight, of the total weight of the organically modified clay.

7. - The bituminous composition according to one of claims 1 to 6, characterized in that the clay is chosen from amongst bentonite and montmorillonite.

8. - The bituminous composition according to one of claims 1 to 7, characterized in that the bitumen base is interposed within the organically modified clay particles.

9. - The bituminous composition according to one of claims 1 to 8, characterized in that the organically modified clay particles have an average size d50 less than or equal to 100 µm, preferably less than or equal to 10 µm.

10. - The bituminous composition according to one of claims 1 to 9, characterized in that the bitumen base consists of a hard grade bitumen or a mixture of hard grade bitumens, in particular chosen from amongst bitumens of grades 35 / 50, 20 / 30 and 10 / 20.

11. - The bituminous composition according to one of claims 1 to 10, characterized in that said bituminous composition has an oxidation index less than or equal to 120, the oxidation index corresponding to the ratio of the complex modulus obtained by rheology (dynamic shear rheometer, under a frequency of 1Hz and at a temperature of 70°C) after 96 hours of oxidation in an aging recipient under pressure at 100°C and 21MPa of air pressure, over the complex modulus obtained prior to oxidation.

12. - A method of preparation of a bituminous composition according to any of the previous claims comprising the mixture of a bitumen base and organically modified clay particles, at a temperature belonging to the range going from 100 to 200°C, preferably to the range going from 120 to 180°C and preferentially to the range going from 140 to 180°C.

13. - A use of organically modified clay particles having a temperature of beginning of degradation under air greater than or equal to 175°C, for improving the resistance to aging over the long term of a bituminous composition comprising a bitumen base, said clay particles being organically modified by an organic modifier chosen from amongst cations which comprise at least one hydrogenated soot moiety and do not comprise the OH functional group, said organic modifier representing from 20 to 50% by weight of the total weight of the organically modified clay, said organically modified clay particles representing from 0.5 to 6% by weight with respect to the total weight of the bituminous composition and said organically modified clay particles having, prior to mixing with the bitumen base, a distance d(001) of at least 2.6 nm.

14. - The use of a bituminous composition according to any of claims 1 to 11, for preparing a sealing coating, a membrane or an impregnation layer.

15. - A bituminous binder characterized in that said bituminous binder comprises a bituminous composition according to any of claims 1 to 11.

16. - A bituminous coated macadam characterized in that same comprises a bituminous binder according to claim 15, aggregates and possibly mineral and / or synthetic loadings.

17. - The use of a bituminous binder according to claim 15, for preparing a surface dressing, a hot macadam, a cold macadam, a cold applied macadam, an emulsion bound graded aggregate or a wearing course, said binder being associated with aggregates and / or recycled millings.