FR2914650A1 - Bitumen composition modified by addition of adipic acid, useful for surface covering and layer formation of rolling pavement or road, comprises adipic acid - Google Patents

Abstract

Bitumen composition (I) modified by addition of adipic acid, comprises adipic acid (0.4-1 wt.%) and has an elevation of ring ball temperature of >= 15[deg] C of composition not containing any adipic acid. An independent claim is included for preparing (I) comprising contacting the adipic acid with the bitumen composition to maintain the adipic acid and bitumen composition at the temperature greater than 130[deg] C under conditions to prevent evaporation or sublimation of the adipic acid.

Description

Modified bitumen composition and processes for preparing this

  The subject of the present invention is a modified bitumen composition and methods of preparing the manufacture of this composition.

  [0002] More particularly, it relates to a modified bitumen composition having improved properties for extreme temperature conditions encountered in most regions of the world.

3] Bitumens are used in many applications, but more particularly for pavement surfacing or roof waterproofing. Bitumens are also called asphalts or bituminous binders.

4] Bitumens can be obtained, in particular, from crude oil, by distillation thereof and / or by de-asphalting the heavy fractions obtained in the various distillations of the oil.

According to the origins, the bitumens consist of various paraffinic or naphthenic oils, aromatic oils, resins and asphaltenes.

6] Bitumens are viscoelastic materials that have the characteristics of hardening and becoming brittle at low temperatures, and / or softening and deforming in a non-reversible manner under high temperature stress. Low temperature and high temperature include low temperatures in winter or cold areas of the world, and high temperatures in warmer regions of the world or during the summer season. There are different grades of bitumen, depending on their consistency at room temperature (penetration value): soft / semi-hard / hard.

7] The properties of bitumens depend on their physicochemical nature, and can be improved during refining processes. He is5

  It is thus possible to improve the high-temperature behavior of bitumens by increasing the asphaltene content: this is the case for example with oxidized bitumens. On the other hand, the cold behavior of these hardened bitumens is substantially degraded. To overcome these disadvantages and improve the properties, it has already been proposed to add various additives that will modify the behavior of bitumens, for example by modifying the microstructure (asphaltenes / maltenes) or, for example, by various physicochemical or mechanical effects of reinforcement (polymers, fibers, etc ...),

9] The performance of use of bitumens is evaluated through the viscoelastic behavior in the field of the limiting temperature of use (-15 C -> + 60 C). The main property sought is a high level of maximum operating temperature corresponding to the ball-ring temperature (TBA). To obtain the desired values, it is then necessary either to use a viscous (hard) bitumen but fragile at low temperature, or to modify the bitumen by adding additives.

  By ball-ring temperature (TBA) is meant the softening temperature determined according to the ring-and-ball test. The procedure for determining this critical temperature is carried out according to a hot procedure described in the standard HTPP5-98 or EN1427.

  The addition of additives in the bitumens is generally carried out at a sufficiently high temperature at which the bitumen is in the form of a low-viscosity liquid, typically around 160 - 175 C. Temperatures above 200 C are avoided by because of the beginning of aging of the bitumen. This additivation is carried out in stirred reactors. The process can take several hours with some additives that are difficult to disperse. After additivation, the modified bitumen is kept at temperature, generally around 135 ° C., in storage tanks with slow stirring. The bitumen is still hot to be pumpable (T> 120 C) during the refining, additivation, transport, storage and use stages. Various acid compounds are used to modify certain properties of the bitumen. This is for example the case of strong acids (HCl, H2SO4, H3PO4) or their precursors.

  Organic acids or their precursors may also be used. Thus, US Pat. No. 5,332,884 describes a process for treating a bitumen with an acidic compound comprising two functional groups capable of grafting onto the bitumen. The proposed acid precursors are, for example, anhydrides and acid chlorides. This addition makes it possible to improve the properties of the bitumen at high temperature without unduly degrading the properties at low temperature. It has also been proposed the use of polymers, and in particular elastomers as in US 4,600,635 or US 5,348,994 or more recently WO 97/43342. The added polymers are generally elastomers in different forms. These polymers may be derived from the synthesis or recycling. Products from the recycling of rubber can be incorporated into the bitumen. Thus, patent WO2004 / 081098 proposes adding to the bituminous binder rubber crumbs. The WO2006 / 107179 patent describes the addition of elastomers in various forms such as particles, sheets, waste.

4] US3061538 discloses the addition of saturated aliphatic dicarboxylic acid, an acid anhydride or an acid chloride to improve the ductility and high temperature deformation resistance properties. This acidic compound is added in a proportion of 0.1 to 10% by weight, preferably between 0.5 and 5% by weight. The acids mentioned in this document are sebacic acid, adipic acid and sebacic acid chloride. In this document, the treatment of bitumen with an acid is carried out at a high temperature (approximately 160 C for adipic acid). During the treatment, a large part of these acids vaporizes and sublimates. To obtain a significant and lasting modification of the properties, it is necessary to add a significant amount of acid in the bitumen, typically 1% or more. An object of the present invention is to provide bitumen compositions with modified properties by the addition of small amounts of certain carboxylic acids and more particularly of certain

  4 di-carboxylic acids and processes for preparing these compositions resulting in limited sublimation of the acid.

7] For this purpose, the subject of the invention is a modified bitumen composition comprising a low adipic acid content of less than 1% relative to the weight of the composition, the adipic acid being introduced according to a particular process. The performance of the bitumens thus modified are described by the gain of the hot softening point called ball-ring temperature (TBA). Suitable bitumens for the invention are especially those obtained from crude oil as described above.

According to the invention, the composition of bitumen modified by the addition of adipic acid is characterized in that it comprises at least 0.4% by weight of adipic acid relative to the weight of the composition and a rise in the TBA with respect to non-additive bitumen greater than or equal to 15 C.

This composition can be obtained by a process comprising a step of adding the desired amount of adipic acid to the bitumen composition to be modified at a temperature of less than 130 ° C., preferably less than about 120 ° C. at higher temperatures, but in a closed chamber to prevent the sublimation or evaporation of adipic acid, possibly a step of maintaining the bitumen composition containing adipic acid at a temperature greater than 130 ° C. under containment conditions preventing the evaporation or sublimation of adipic acid, and a step of homogenizing the adipic acid mixture and bitumen composition by agitation performed under confinement conditions preventing the evaporation or sublimation of adipic acid . The methods described above allow to add to the bitumen to modify a specific amount of adipic acid necessary and sufficient to obtain a change in properties, without risk of evaporation or sublimation of adipic acid. Accordingly, with the methods of the invention, it is possible to control the amount of adipic acid present in the composition. According to another characteristic of the invention, the bitumen composition may contain additives such as, for example, thermoplastic resins, elastomers, plasticizers, fillers or the like. Thus, the compositions of the invention may include additives selected from the group consisting of: LDPE (low density polyethylene), HDPE (high density polyethylene), EVA (ethylene vinyl acetate), SBR (styrene butadiene elastomer), SBS (styrene butadiene styrene elastomer), PS (polystyrene), ABS (acrylonitrile butadiene styrene), CMC (carboxymethyl cellulose), PVA (polyvinylacetate), PVC (polyvinyl chloride), polybutadiene, HIPS (high resistance polystyrene). It may also comprise rubber crumbs as described in patent application WO2004 / 081098 previously advantageously cited at a concentration by weight of between 5% and 10% relative to the weight of bitumen. additives, the adipic acid content is expressed by weight of adipic acid relative to the weight of bitumen, without additives. According to one characteristic of the invention, the concentration of adipic acid in the bitumen composition is advantageously between 0.5% and 0.8% by weight.

4] However, when the bitumen composition comprises an additive such as elastomers, preferably SBS, or rubber crumbs, the adipic acid concentration is preferably between 0.4% and 0.6% by weight.

According to the invention, the adipic acid can be added to the bitumen simultaneously with the other additives, before or after the other additives. It is also possible to prepare a premix of adipic acid and one or more additives before the addition in the bitumen. However, this last embodiment is only possible if the adipic acid and the additive do not react with each other.

The invention also relates to methods of manufacturing a modified bitumen composition, as described above. More particularly, these manufacturing processes relate to several modes of addition and mixing of adipic acid with the bitumen to be modified.

  In a first embodiment of the process, the adipic acid is brought into contact with the bitumen, for example by adding adipic acid in the bitumen, then maintaining the bitumen / adipic acid mass at a temperature of greater than about 130 ° C., advantageously between 135 ° C. and 170 ° C., under conditions which prevent the sublimation or evaporation of the adipic acid. The addition at a temperature greater than 130 C makes it possible to obtain, in an extremely rapid manner, a certain reactivity of the adipic acid with respect to the bitumen with generation of chemical, physico-chemical or electronic bonds between the acid molecules. adipic and the compounds forming the bitumen. The reaction is immediate, the duration of the mixture being determined by obtaining a homogeneous mixture.

8] In one embodiment of the process, the mixtures obtained after maintaining at a temperature above 130 ° C are cooled to a temperature below about 130 ° C., preferably below about 120 ° C. and then homogenized by stirring, preferably mechanical stirring.

9] It is also possible to achieve this homogenization before cooling the mixture to a temperature below about 130 C, preferably below 120 C, if this step is performed in a confined chamber avoiding the sublimation of adipic acid.

According to another characteristic of the process, the contacting of the bitumen with adipic acid is carried out either by the addition of adipic acid in the bottom of a tank and then pouring the bitumen into said tank, or by adding adipic acid in the heart of the bitumen mass contained in a tank. By addition to the core of the bitumen mass, it should be understood that the point of addition of the adipic acid must be located in the bitumen mass at a distance of at least 1 cm, preferably about 5 cm from the surface top of the bitumen mass.

1] Thus, when the temperature is maintained at a value greater than 130 ° C., advantageously between 135 ° C. and 170 ° C., the mass of bitumen situated above the adipic acid forms a buffer preventing the sublimation or evaporation of the product. adipic acid.

2] The mixing step is then advantageously carried out at a relatively low temperature, typically less than 130 ° C., preferably

  7 lower than about 120 C, temperature level for which on the one hand the bitumen has a fluidity sufficient to be homogenized and secondly the phenomenon of sublimation or evaporation of adipic acid no longer exists or is very low or negligible. This method of adding adipic acid makes it possible to add only the amount of acid necessary to obtain a modification of the properties of the bitumen. According to another embodiment of the process for manufacturing a modified bitumen composition according to the invention, the addition of adipic acid and the mixing or homogenization are carried out in a confined space, such as a tank with closed agitation or a static mixer, for example.

4] Since the space is confined, the sublimation or evaporation of the adipic acid is prevented or limited, the homogenization can be carried out at a temperature greater than 130 ° C., advantageously between about 135 ° C. and 170 ° C., the duration of the maintaining at this temperature can be much shorter than that required in the absence of agitation. To minimize the phenomenon of sublimation of adipic acid, it is advantageous that the confined space is filled to at least 90% by the mixture bitumen / adipic acid. In addition, to limit losses of adipic acid, it may be preferable to maintain at a high temperature all internal parts of the equipment used to prevent acid deposition on walls or cold parts of the installation.

In the embodiments of the method described above, the bitumen to which the adipic acid is added may already contain certain additives, or these may be added to the composition after or during the homogenization stage of the composition. .

7] The modified bitumen compositions of the invention are especially used for the formation of surface coating and more particularly for the formation of the wearing course of a roadway or road. For this, it can be advantageously mixed with gravel or granules of various kinds.

  [0038] The modified bitumens of the invention have improved properties at high temperatures. Thus, the bitumens of the invention has an elevation of the TBA of the order of 20 to 30 C, that is to say much higher than that obtained by modifying the bitumens by addition of elastomers or polyphosphoric acid. These bitumens also have a low temperature behavior (embrittlement) at least equivalent to that of unmodified bitumens.

9] This improvement of the properties is obtained for very low concentrations of adipic acid, that is to say with 0.4 or 0.5% of adipic acid. This effect is also observed with bitumens comprising additives such as elastomers such as SBS elastomers or rubber crumbs. Other advantages, details of the invention will appear more clearly in view of the examples given below only for illustrative and illustrative purposes.

1] For the realization of the examples, two types of bitumens were considered, in order to take into account the great physicochemical diversity of these products:

  -a weakly acidic paraffiriic type bitumen (Middle East) from Shell (Petit Couronne refinery) and -a much more acidic naphthenic type bitumen (Venezuela) from Nynas (Nynashaam refinery).

2] The performances of these two bitumens were measured according to the norms in force: - Penetration at room temperature according to the norm (CEN-AFNOR EN1426), this characteristic is expressed in tenth of a millimeter and will be denominated Péné in the continuation of the text and , softening temperature or ball-ring TBA according to CEN-AFNOR EN1427. A critical temperature can also be calculated from the results of rheology DSR, according to the criteria defined by the Strategic Highway Research Program (SHRP, USA). This temperature, before aging,

  9 called Tc is calculated according to the method AASHTO TP5-97. This critical temperature is particularly measured in the case of bitumens modified with polymers, for which the measurement of TBA can sometimes be erroneous because of the absence of shear. The characteristics of these bitumens are summarized in Table I below: Table I Shell 70/100 Nynas 50/70 Tba (C) 47 50 Pene in 1 / 10mm 72 64 Tc (C) SHRP 65 70 10 [ These bitumens can be modified by the addition of an elastomer type additive typically dosed at 3% by weight (SBS) or by a strong mineral acid additive dosed at 1.2% by weight (APP polyphosphoric acid). The characteristics of these additive bitumens are given as an indication in Table II below:

  Table II: Bitumen 70/100 + 3% Bitumen 70/100 + 1.2% SBS APP _ 53.2 51.7 Tba (C) Pene in 1 / 10mm 62 65 Tc (C) SHRP 71.8 74.6 Example 1 Addition of adipic acid according to the embodiment 20 in confined space.

7] Various tests were carried out using a method of adding adipic acid in bitumen contained in a confined (closed) environment. Attempts have been made, for example, with a double walled Pyrex reactor equipped with a stirring device. The heating is provided by a circulation of temperature controlled oil. Any other closed system can be used.

8] A quantity of bitumen (100 g) was previously heated in a beaker (250 ml) at 165 C. This bitumen is then poured into a container5

  10 equipped with a lid, then kept at 165 C for 30 min. The temperature is measured by a temperature probe immersed in the bitumen. The container is opened, and the adipic acid is introduced rapidly: for example 0.5 g of acid per 100 g of bitumen. The container is then closed, and the mixture is homogenized by stirring (300 rpm) for 1 hour at 165 C. The bitumen thus modified is then cooled to a lower temperature, typically 135 C, with slow stirring for about 15 hours. These conditions simulate an industrial process: additivation in a closed reactor, then storage in a closed tank at a lower temperature. The bitumen is then poured directly into various molds in order to carry out the characterization tests on standard test specimens.

9] In Table III below are collected the properties of different bitumen compositions modified with various concentrations of adipic acid (ADOH).

  Table III Bitumen + 0.2% + 0.3% + 0.4% + 0.5% 70/100 ADOH ADOH ADOH ADOH TBA (C) 47 46.5 45.5 53 93 [0050] The results obtained show that the elevation of TBA appears only for an adipic acid concentration of 0.4%. This elevation of TBA is substantially equivalent to that obtained with 1.2% polyphosphoric acid. For an adipic acid content greater than 0.4%, the performance then becomes extremely high: TBA = 93 C for 0.5% ADOH. However, such hot performance gains could raise fears of embrittlement of low temperature bitumen. A measurement of the Tg of these compositions by DSC shows that it remains substantially constant and equal to that of the unmodified bitumen and therefore there would be no modification of the bitumen that could lead to a problem of cold embrittlement. In addition, the evolution of the consistency at room temperature (Péné) corresponds to a gain of about one grade on the composition, according to the classification of viscous products which is illustrated by the evolution of the penetrability characteristic.

1] As the completion of the addition and mixing process is conducted in a closed environment, no whitish fumes are formed. Keeping all parts of the installation temperature-free avoids any risk of deposits.

2] Example 2 Adipic acid addition according to the open space embodiment. An amount of bitumen (> 100 g) was previously heated in a beaker (250 ml) at 165 C. 100 g of this bitumen thus heated is then poured into a beaker containing in its bottom, adipic acid: for example 0.8 g of adipic acid per 100 g of bitumen. The temperature is measured by a temperature probe immersed in the bitumen. The container is opened, and the temperature is maintained at 165 ° C. for 30 minutes without stirring. The temperature is then lowered to 120 ° C. and the mixture is homogenized by stirring (300 rpm) for 30 minutes. The bitumen is then poured directly into various molds in order to perform characterization tests on standard test specimens. For an adipic acid content of 0.8%, the measured value of TBA is then extremely high: TBA = 100 C.

4] Another series of tests was carried out with a lower content namely 0.5% of adipic acid. The acid is incorporated as described above: addition in the bottom of the beaker before the addition of the bitumen mass at 165 ° C. without any stirring, in an open medium, then homogenization at a lower temperature (below 130 ° C. by stirring) for 30 minutes). The measured TBA value is still extremely high, and this for only 0.5% of adipic acid: TBA = 101 C.

Example 3: Test with 0.4% Adipic Acid in Combination with an SBS Polymer According to the Confined Containment Mode.

  A test series was performed by combining adipic acid and an SBS polymer. The bitumen has been previously additivated with a polymer according to a procedure specific to this type of product. Shell 70/100 bitumen and Kraton 1184R type SBS polymer were used. The SBS bitumen-polymer mixture was produced in two stages: a dispersion at 175 ° C. in a Silverson-type shearing kneader at 3000 rpm for 1 hour, followed by a maturation of the mixture at 165 ° C. while mixing at a slow rate. (300 rpm) for 2 hours where the polymer swells due to absorption of some of the bitumen oils. Different polymer-modified bitumen compositions (BmP) have thus been produced: in particular a standard composition containing 3% by weight of SBS, and a composition with a reduced content of typically 2% by weight of SBS.

8] The adipic acid is incorporated in a confined (closed) environment in the polymer modified bitumen previously prepared according to the procedure described in Example 1. The following conditions were retained: incorporation carried out at 165 ° C. with stirring (400 rpm) in a closed environment, then maintain the bitumen at 135 C for 15 hours always in a closed environment. These conditions simulate an industrial process: additivation in reactor, then storage in lower temperature tank.

0] The performance gain observed is extremely high: for 0.4% of adipic acid with only 2% of SBS, the TBA of the polymer modified bitumen thus goes from 51.2 C to 80 C (a rise of nearly 30 C).

1] Table IV summarizes the characteristics of various compositions showing the important effect obtained by addition of adipic acid in a polymer-added bitumen. Table IV Bitumen + 2% SBS + 0.4% + 2% SBS 70/100 ADOH + 0.4% ADOH TBA (C) 47 51.2 53 80 Tc (C) 65 70 71 102 [0062] The value of Pene penetration increased from 72 (d / 10 mm) for unmodified 70/100 bitumen to 38 (d / 10 mm) for the 2% SBS + 0.4% Adipic Acid composition. Rheology measurements (DSR) carried out on a viscoanalyser (Metravib) allow a finer characterization of the modified bitumens, and in particular the calculation of a critical temperature Tc according to the SHRP criteria (Strategic Highway Research Program, USA): the gains observed Tc confirm what is observed at the level of the TBA. 20 25

  Another assay was carried out by addition of 0.4% adipic acid in a bitumen modified with 2% SBS at 165 ° C without stirring and holding for 30 min then homogenization at lower temperature (about 120 ° C). ) with stirring for 1h. The measured TBA is then equal to 94 C.

4] Example 4: Test with 0.4% of Adipic Acid in combination with rubber crumbs according to the mode of addition in confined space. The rubber crumb can be used in bitumens as a total or partial substitution of the SBS. A series of tests was carried out, by association of adipic acid and rubber crumb.

  [0066] A modified rubber crumb asphalt was produced according to the procedure specific to this type of product. The bitumen used is a 70/100 bitumen. Two compositions were prepared by adding 5% by weight and 10% by weight of 175 C rubber crumb.

  Adipic acid is added in these compositions according to the embodiment of Example 1. The following conditions were retained, close to those of an industrial process: incorporation carried out at 165 ° C. with stirring in medium closed for 1 hour, then maintaining the bitumen at 135 C for 15 hours always in a closed environment. [C) 068] The performances of the bitumen compositions obtained are:

With 10% rubber crumb, the viscosity of the bitumen begins to be strongly modified, and the TBA rise is +9 C compared to the unmodified bitumen (TBA = 56 C). The performances are therefore slightly higher than those of bitumen modified with 3% of SBS.

For compositions containing 5% of adipic acid-free rubber crumb, the viscosity is little changed and the rise in TBA is only +4 ° C (TBA = 51 ° C). The compositions containing 5% by weight of rubber crumb and 0.5% by weight of adipic acid, the increase of TBA is + 15.5 C. The measured TBA is equal to 66.5 C, with a viscosity correct. These properties are shown in Table V below Table V Bitumen + 10% + 5% + 0.5% + 0.5% 70/100 Crumb Powder ADOH ADOH + Rubber Rubber 5% Crumb Rubber Tba (C) 47 56 51 93 66.5 Tc (C) 65 79.5 71 97 [0072] The penetration value (Peneus) of the 0.5% adipic acid + 5% powdered rubber mixture is 35 (in 1/10 mm). Rheology measurements (DSR) carried out on a viscoanalyzer (Metravib) allow a finer characterization of the modified bitumens, and in particular the calculation of a critical temperature Tc according to the SHRP criteria (Strategic Highway Research Program, USA). The presence of 0.5% adipic acid makes it possible to reduce the powdery powder concentration for an equivalent and even higher level of properties.

3] An attempt to manufacture a composition containing 5% powder and 0.4% adipic acid was carried out by incorporation at 165 ° C. without stirring adipic acid into the bitumen modified with the crumb and holding for 20 minutes. minutes and then homogenization by stirring at a temperature of 120 C for 1 hour. The measured TBA is then equal to 66.5 ° C.

  [C) 74] Example 5: Test with Adipic Acid, in the presence of basic filler

  [C) 75] In many applications, particularly for the production of asphalt, the bitumen compositions comprise fillers called filler having a particle size less than 20 m. These fillers can be siliceous mineral compounds generally derived from aggregates, or they can come from other basic type fillers such as lime or cements.

  In this case, some reactivity can occur between these basic fillers and the acidic additives such as, for example, adipic acid or polyphosphoric acid. Thus, in the presence of 20% by weight of basic type filler, all the polyphosphoric acid (1%) is neutralized and the performance gain of the bitumen provided by this acid is then completely eliminated.

7] A series of tests was carried out with adipic acid in the presence of a commonly used basic filler of cement origin called Calcia. The results summarized in Table VI below show that the effect of adipic acid on the properties of the bitumen is preserved in the presence of basic type of fine filler.

  Table VI Bitumen + 0.9% + 0.9% + 0.9% 70/100 ADOH ADOH + ADOH + 1% filler 20% filler Calcia Calcia TBA (C) 47 82 90 89 [0078] Example 6: Comparative Tests

9] Various tests were carried out for comparison with other carboxylic acids according to the procedure of Example 1.

0] A first series of tests was carried out with citric acid (non-dicarboxylic acid) and stearic acid 1%. These acids do not modify the properties of the bitumen. The results obtained are collated in Table VII below.

  Table VII Bitumen + 1% + 1% + 1% + 0.5% 70/100 ADOH Acidic acid Citric acid Maleic stearic acid TBA (C) 47 82 48 46.5 50 Tc (C) 64.75 83.5 65 63.5 66.3

  Other carboxylic acids have also been evaluated such as succinic acid, glutaric acid. As the melting points of these acids are relatively different: 90 C for glutaric acid, and 190 C for succinic acid, the procedures for adding these acids were carried out at different temperatures indicated in Table VIII. below which gather the results obtained.

  Table VIII Bitumen + 1% + 1% + 1% + 1% 70/100 ADOH Acid Acid Acid (165 C) Succinic Succinate Glutaric (175 C) (195 C) (165 C) TBA (C) 47 82 48.5 48.5 5210

Claims (11)

claims   1. Composition of bitumen modified by addition of adipic acid, characterized in that it comprises between 0.4% and 1% by weight of adipic acid relative to the weight of the composition and has an elevation of TBA of greater than or equal to 15 C relative to the TBA of the composition containing no adipic acid.   2. Modified bitumen composition comprising adipic acid, characterized in that it comprises at least 0.4% by weight of adipic acid relative to the weight of the composition and an elevation of the TBA greater than or equal to 15 C and in that it is obtainable by a process comprising a step of adding adipic acid to the bitumen composition to be modified, a step of maintaining the bitumen composition containing the adipic acid to a temperature greater than 130 ° C. under conditions preventing the evaporation and sublimation of adipic acid and a step of mixing the adipic acid and the bitumen composition by stirring carried out either at a temperature below 130 ° C. or in a confined space to prevent sublimation and evaporation of adipic acid.   3. Composition according to claim 1 or 2, characterized in that it comprises additives selected from the group consisting of thermoplastic resins, elastomers, plasticizers, fillers.   4. Composition according to one of claims 1 to 3, characterized in that it comprises at least one additive selected from the group consisting of LDPE (low density polyethylene), HDPE (high density polyethylene), EVA (ethylene vinyl acetate) , SBR (styrene butadiene elastomer), SBS (styrene butadiene styrene elastomer), PS (polystyrene), ABS (acrylonitrile butadiene styrene), CMC (carboxymethyl cellulose), PVA (polyvinylacetate), PVC (polyvinyl chloride), polybutadiene, HIPS (high impact polystyrene), rubber crumb. 18   5. Composition according to one of the preceding claims, characterized in that the adipic acid concentration is between 0.5% and 0.8% by weight.   6. Composition according to claim 4, characterized in that the weight concentration of adipic acid is between 0.4% and 0.8% relative to the weight of bitumen.   7. Composition according to claim 4 and 6, characterized in that the weight concentration of rubber crumb is between 5 0/0 and 10% by weight relative to the weight of bitumen.   8. A method of manufacturing a modified bitumen composition according to one of claims 1 to 7, characterized in that it consists in contacting the adipic acid with the bitumen composition, maintaining the adipic acid and the bitumen composition at a temperature greater than 130 ° C. under confinement conditions preventing the adipic acid from evaporating or subliming. 20   9. Process according to claim 8, characterized in that the adipic acid is added and mixed with the bitumen in a static mixer at a temperature above 130 ° C., preferably between 135 ° C. and 170 ° C.   10. Method according to claim 8, characterized in that the adipic acid is added to the bitumen composition contained, with stirring, in a closed chamber, at a temperature above 130 C, preferably between 135 C and 170 C . 30   11. Process according to claim 8, characterized in that the adipic acid is added to the bitumen composition at an injection point situated at a distance greater than 1 cm, preferably greater than 5 cm, from the surface of the composition. of bitumen, the adipic acid / bitumen composition assembly is maintained, in the absence of agitation, at a temperature greater than 130 ° C., preferably between 135 ° C. and 170 ° C., for at least 15 minutes, said assembly being then subjected to stirring after cooling to a temperature below 130 C for a time sufficient to obtain a homogeneous mixture.