Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica

Definitions

• the present invention relates to a process for improving the physicochemical properties of bitumen compositions as well as to new bitumen compositions with improved properties and their uses, in particular for the preparation of bituminous mixes for road surfaces.
• bitumen-type materials such as asphalt and malthe for pavements, roofing materials, various coatings, mortar and bending.
• Bitumen compositions have been prepared by adding suitable additives such as aggregates or fillers to the bitumen-like materials mentioned above.
• suitable additives such as aggregates or fillers
• Such compositions have numerous drawbacks when they are used as such for different applications: there may be mentioned in particular a high sensitivity to temperature, poor adhesion to aggregates, poor properties at low temperatures, low resistance to abrasion, low impact resistance.
• the main constituents are bituminous mixes which consist of 95% by mass of granules and 5% by mass of bitumen which serves as a binder.
• this binder is predominant on the properties of the road which is subject to three types of mechanical stress: thermal fracture, fatigue and rutting.
• thermal fracture ie bitumen
• the binder vitrifies and becomes brittle. It can then form long transverse cracks due to thermal stresses (thermal fractures) which are microcracks due to the heterogeneity of the material.
• thermal fractures thermal stresses
• microcracks due to the heterogeneity of the material.
• the roadway can still crack under the effect of fatigue. This results in a multitude of mainly longitudinal interconnected cracks.
• bitumen changes from the solid state to the viscous state, more and more fluid. Also, the repeated passage of high masses constituted by vehicles, whose heavy vehicles on the roadway contribute to deform the bitumen permanently and therefore the roadway. This phenomenon is at the origin of ruts.
• the binder also ensures the waterproofing of the roadway, thus protecting the foundations of the road.
• the main characteristics required of the road and therefore of the composition of bitumen which serves as a binder are therefore: - good resistance to cracking at low temperature (typically - 15 ° C),
• Another object of the present invention is to provide a method for improving the rheological and mechanical properties of bitumen compositions.
• Another object of the present invention is to provide a method for improving the mechanical strength of bitumen compositions at high temperatures.
• Another object of the present invention is to provide a process for improving the properties of bitumen compositions which exhibits storage facilities and good redispersibility of the additives used in bitumen compositions.
• the present invention which in fact relates to a process for improving the physicochemical properties of bitumen, characterized in that a sufficient quantity of optionally functionalized amorphous silica is added to the bitumen composition.
• the present invention also relates to a bitumen composition capable of being obtained by the process.
• the present invention also relates to a hot mix preparation process which implements the bitumen composition of the invention.
• the present invention also relates to a process for the preparation of cold mixes which implements the bitumen composition of the invention.
• the present invention relates first of all to a process for improving the physicochemical properties of bitumen, characterized in that a sufficient quantity of amorphous silica, optionally functionalized, is added to the composition of bitumen.
• the amorphous silica can be a natural silica or a synthetic silica such as precipitated silicas, silica gels or combustion silicas.
• a precipitated silica is used. It may for example be a Tixosil 38A, Tixosil 38D or Tixosil 365 silica from the company RHODIA.
• the precipitated silica may be in the form of substantially spherical beads, in particular of average size of at least 80 microns, for example at least 150 microns, obtained by means of a nozzle atomizer, as described for example in document EP 0018866. It can for example be silica called Microperle. It may for example be a Tixosil 38X or Tixosil 68 silica from the company Rhodia.
• the precipitated silica can be a highly dispersible silica, like the silicas described in documents EP 520862, WO 95/09127 or WO 95/09128, which facilitates its dispersion in bitumen and has a positive effect on the mechanical properties of the material obtained. .
• WO 95/09127 describes more precisely a precipitated silica having: a specific surface CTAB (Sr ⁇ / / B) of between 140 and 240 ⁇ g,
• S CTAB specific CTAB surface
• a highly dispersible silica mention may in particular be made of a Zl 165 MP silica or a Zl 115 MP silica from the company Rhodia.
• Amorphous silica can be silica with low water uptake.
• low water uptake is meant a water uptake of less than 6% and preferably less than 3%.
• They may be precipitated silicas described in patent application FR 01 16881 filed on December 26, 2001 by the company Rhodia, fumed silicas or partially dehydroxylated silicas by calcination or by surface treatment.
• the amorphous silica of the invention can be functionalized before it is added to the bitumen.
• silylation reaction can be carried out by a silylation reaction using a coupling agent chosen from the family of silanes.
• a coupling agent chosen from the family of silanes.
• silanes alkylsilanes or functional silanes such as amino-silanes, thiol-silanes or epoxy-silanes.
• the amount of coupling agents introduced into the amorphous silica is between 0.1 and 30% by weight relative to the weight of the amorphous silica.
• the amount of coupling agents introduced into the amorphous silica is between 5 and 15% by weight relative to the weight of the amorphous silica.
• the silylation reaction which is a grafting of the silane onto the silica can be carried out in an alcoholic medium in the presence of a catalyst.
• This catalyst can be an acid such as acetic acid, or a base such as ammonia.
• the reaction medium is then centrifuged. The mother liquors are then removed and the residue is washed with distilled water.
• a powder is recovered with a level of coupling agent of between 0.5 to 30% by weight of coupling agent relative to the total weight of the functionalized silica.
• this optionally functionalized amorphous silica of the invention is that it is very stable during storage, very easy to handle, it is very fluid, it does not clot and it is redispersed particularly well in bitumen compositions, this which facilitates the implementation of processes for preparing bitumen compositions with improved performance and processes for preparing bituminous mixes "hot” and bituminous mixes “cold”.
• the optionally functionalized silica must be added to the bitumen composition in a sufficient amount.
• the amount of optionally functionalized amorphous silica introduced into the bitumen composition is between 0.01 and 20% by weight of optionally functionalized amorphous silica relative to the total weight of the bitumen composition.
• the amount of optionally functionalized amorphous silica introduced into the bitumen composition is between 0.1 and 7% by weight of optionally functionalized amorphous silica relative to the total weight of the bitumen composition.
• bitumens to which the silica of the present invention can be added include natural bitumens, pyrobitumes and artificial bitumens. Particularly preferred bitumens are those used for pavements, such as asphalt or malthe. Even more preferably, asphalt is used.
• the first embodiment relates to a method for improving the physicochemical properties of the bitumen composition comprising the following steps: 1-the bitumen composition is heated to a temperature between 120 and 190 ° C; 2 — a sufficient amount of optionally functionalized amorphous silica is added to the bitumen composition of step 1 with stirring.
• the silica can optionally be functionalized “in situ” in the bitumen composition. That is, it is possible to add the coupling agent independently of the silica in step 2 of this process.
• the present invention also relates to a bitumen composition capable of being obtained by the process described above.
• the present invention also relates to a process for the preparation of hot mixes which implements the bitumen composition capable of being obtained by the above process.
• This process includes a step additional to the previous process which consists in adding, with stirring and at a temperature between 120 and 190 ° C, aggregates in the bitumen composition before, simultaneously, or after the addition of optionally functionalized silica from step 2.
• the aggregates are preheated to a temperature above 120 ° C.
• the present invention also relates to a bitumen composition capable of being obtained by the process described above.
• the second possible embodiment for the incorporation of the amorphous silica optionally functionalized in the bitumen composition is carried out at room temperature. It is a “cold” preparation process.
• This process includes the following steps:
• bitumen emulsion is prepared by mixing water, bitumen and an emulsifier at room temperature;
• bitumen emulsion of step 1 A sufficient quantity of amorphous silica, optionally functionalized, is incorporated into the bitumen emulsion of step 1 with stirring at room temperature; 3-the emulsion obtained in step 2 is spread to obtain a uniform layer of the mixture obtained in step 2; 4-we break the bitumen emulsion.
• the present invention also relates to a bitumen composition capable of being obtained by the process described above.
• the silica can optionally be functionalized “in situ” in the bitumen composition. That is, it is possible to add the coupling agent independently of the silica in step 2 of this process.
• the present invention also relates to a “cold” mix preparation process which implements the bitumen composition capable of being obtained by the above process.
• This process comprises a step additional to the previous process which consists in adding, with stirring and at room temperature, aggregates in the bitumen composition after the addition of optionally functionalized silica from step 2.
• the present invention also relates to a bitumen composition capable of being obtained by the process described above.
• This process comprises the following stages: 1-the bitumen composition is heated to a temperature between 120 and 190 ° C;
• An emulsion of the bitumen obtained in step 2 is prepared by mixing water, said bitumen and an emulsifier; 4-the emulsion obtained in step 3 is spread to obtain a uniform layer of the mixture obtained in step 3;
• the present invention also relates to a “cold” mix preparation process which implements the bitumen composition capable of being obtained by the above process.
• This process includes a step additional to the previous process which consists in adding, with stirring and at room temperature, aggregates in the bitumen emulsion obtained in step 3 of the process.
• the amount of optionally functionalized amorphous silica introduced into the bitumen composition is between 0.01 and 20% by weight of optionally functionalized amorphous silica relative to the total weight of the bitumen composition.
• the amount of optionally functionalized amorphous silica introduced into the bitumen composition is between 0.1 and 7% by weight of optionally functionalized amorphous silica relative to the total weight of the bitumen composition.
• bitumen compositions of the invention may also contain other additives commonly used in the field of bitumen.
• the emulsifiers used to emulsify bitumen are emulsifiers usually used by a person skilled in the art in this technical field.
• bitumen used is previously oxidized hot by contact with air.
• Example A Preparation of a bitumen composition
• the silica used is a Zl 165 MP silica from the company Rhodia. It is used as it is or it undergoes a preliminary treatment.
• the mixture After ripening, the mixture is centrifuged and washed 5 times with the same volume of water.
• % N 0.37 level of coupling agent used in the powder: 6.5% by weight of silane relative to the total weight of the functionalized silica.
• the mixture After ripening, the mixture is centrifuged and washed 5 times with the same volume of water.
• Bitumen grade 70/100 (Pen) was used for the tests. Origin bitumen
• bitumen is removed from a barrel, then placed in a beaker: the beaker is then heated on a hot plate to 170 ° C.
• the mixture is then maintained at 170 ° C. for approximately 15 minutes with vigorous stirring using a rotary agitator (260 rpm).
• the temperature is kept strictly below 180 ° C, so as not to alter the characteristics of the bitumen.
• the mixture is kept for 5 minutes at approximately 170 ° C. under slow speed stirring in order to eliminate any air bubbles which may have formed.
• the mixing is then finished, and ready for use.
• Example B Evaluation of bitumen compositions 1.2 / Rheology tests The rheological characterization of the additive bitumen is made according to a procedure derived from SHRP standards: DSR Dynamic Shear Rheometer tests (AASHTO TP5-98).
• the rheology tests are carried out in annular shear, using a Metravib viscoelasticimeter.
• the liquid bitumen is introduced into the shear cell heated beforehand to 110 ° C. When the temperature has dropped to around 45 ° C, the bitumen no longer flows and the entire structure is tightened and ready for measurements.
• the bitumen sample has a thickness of 1mm on a height of 5mm (cylindrical geometry).
• the tests are carried out at different temperatures (30, 40, 50 and 60 ° C) and in a frequency range making it possible to demonstrate the behavior of the material: 7.8 - 15.6 - 31.2 - 62.5 - 125 and 200 Hz.
• the results obtained relate to the Coulomb module (complex module) G *, the elastic components G 'and viscous G ", and the phase angle ⁇ . These results can be represented either at iso-frequency as a function of temperature, or at iso-temperature (isotherms) as a function of frequency.
• Table 1 collects the values measured at 60 ° C, for a frequency of 7.8 Hz.
• phase angle ⁇ remains substantially constant, except for a rate of 15% functionalized epoxy silica which reflects a more elastic behavior of the bitumen additive.
• Table 2 collects the values measured at 25 ° C (and 40 ° C for the phase angle ⁇ ), for a frequency of 7.8 Hz.
• the critical temperature Te is determined according to the criterion described in the SHRP procedure
• Te is the temperature for which the ratio G * / sin ⁇ is greater than 1000 Pa.
• the thermal suceptibility of bitumen is determined by an IS index: thermal susceptibility index.
• the critical temperature Te is greatly increased in the presence of 5% silica. Similarly, there is a significant drop in the thermal susceptibility IS. The phase angle ⁇ (at 40 ° C) is significantly reduced, which translates into more elastic behavior of the bitumen with additives.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=32241530

Family Applications (1)

Country Status (8)

Families Citing this family (12)

Family Cites Families (8)

• 2002
  • 2002-11-22 FR FR0214677A patent/FR2847584A1/fr active Pending
• 2003
  • 2003-11-21 WO PCT/FR2003/003446 patent/WO2004048456A2/fr not_active Ceased
  • 2003-11-21 EP EP03786044A patent/EP1565521A2/de not_active Withdrawn
  • 2003-11-21 US US10/540,783 patent/US7335251B2/en not_active Expired - Fee Related
  • 2003-11-21 BR BR0316484-5A patent/BR0316484A/pt not_active IP Right Cessation
  • 2003-11-21 AU AU2003295050A patent/AU2003295050A1/en not_active Abandoned
  • 2003-11-21 MX MXPA05005484A patent/MXPA05005484A/es unknown
  • 2003-11-21 CA CA002507114A patent/CA2507114A1/fr not_active Abandoned

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events