FR2705699A1 - Method for coating a material with a binder in the form of an emulsion, binder in the form of an emulsion intended in particular for the coating method and coated material obtained - Google Patents

Abstract

The invention relates to a method for coating a material crushed from massive rocks or alluvial rocks, with a binder, consisting in bringing the said binder into contact with the said material in a mixer, characterised in that the binder is in the form of an emulsion, the said emulsion being obtained by mixing an inverse water-in-oil emulsion of the said binder and a direct oil-in-water emulsion of the said binder. A further subject of the invention is the binder emulsion intended in particular for implementing the method and the coated material obtained by the said method.

Description

 The subject of the present invention is a method of coating a material originating from the crushing of massive or alluvial rocks with a binder, the method consisting in bringing said binder into contact with said material in a kneader.

 The invention also relates to a binder in the form of an emulsion intended in particular for implementing the coating process and the material thus obtained.

 The materials suitable for the present invention are all materials originating from the crushing of massive or alluvial rocks as well as gravels or natural sands, these materials being those commonly used in road engineering.

 One of the traditional coating methods for this type of material consists in mixing the divided material with a binder in the form of a conventional cationic "oil in water" bitumen emulsion.

 However, the result of the coating of the materials by bitumen emulsion depends largely on the mineralogical nature of the materials as well as on the proportion of fines ("part less than 80 microns") present in the particle size curve.

 In addition, in the traditional coating process of the cold dense or severe emulsion coated type, one of the drawbacks is the loss of part of the water contained in the mixture.

 It has indeed been proposed in French patent 2,175,610 to replace the traditional bitumen emulsion with a modified bitumen emulsion.

 It has also been proposed to coat the fine parts with a particle size of less than 2 mm separately before reintroducing them during mixing.

 However, this results in a significant additional cost of the coated materials (more expensive and more rigid binder in the case of the binder modified according to patent FR 2 175 610 and a double coating in the case of the separate coating of fine particles of small particle size).

 The subject of the present invention is a method which makes it possible to avoid the drawbacks mentioned above, that is to say in particular making it possible to overcome the constraints linked to the particle size curve (proportion of fines) and this, in a single coating.

 The object of the invention is also to propose a method preventing loss of substantial water in the mixture.

 Another object of the present invention is also to provide a process making it possible to obtain cold mixes of the closed type in which all the surfaces of material are covered with binder and which can be stored for several days before their installation.

 According to the present invention, the coating process is characterized in that the binder is in the form of an emulsion, said emulsion being obtained by mixing a reverse water-in-oil emulsion of said binder and a direct oil emulsion in water of said binder.

 Among the binders suitable for the present invention, mention may be made of bitumen or coal pitch, although the use of the latter binder is currently experiencing a certain recession.

 Other equivalent binders can also be used. For example, it is possible to use in the context of this process a mixture of bitumen and fluid bitumen ("cut back") 0/1 heated to 1300C, the proportion of fluid bitumen ("cut back") in the mixture can vary from 0 to 100%.

 In general, all well-known hydrocarbon binders can be used to carry out the process, in particular unsaturated olefinic hydrocarbons such as polyethylene, polypropylene, polybutene, polystyrene or mixtures thereof as is described in French Patent No. 1,248,940 or American Patent 4,529,407. However, on an economic level, it is preferable to use bitumen.

 It should be understood that in general, the invention is not limited to the use of a strictly identical binder to form the oil in water emulsion and the water in oil emulsion. Although obviously, this implementation is the easiest industrially, binders of different composition can be used without harming the invention for both emulsions.

 It is well known that, in general, an emulsion is formed by mixing an oily phase and an aqueous phase, the emulsion being stabilized by an emulsifying system.

 In the context of the present invention, the reverse emulsion is preferably a cationic emulsion, that is to say that the emulsifying system comprises one or more cationic surfactants, in particular those having amine groups.

 Mention may be made, by way of indication, of all the hydrocarbon chains having one or more amine groups such as coconut amine and tallow propylene diamine. In order to form the NH4 + group, this system also includes one or more acidic compounds which make it possible to yield a proton. Among these compounds, mention may be made of organic acids such as glacial acetic acid or mineral acids such as hydrochloric acid. Other cationic emulsifying systems may also be suitable. It is thus possible to replace the cationic emulsifier of the amine type with an amido-amine, an imidazoline, a quaternary ammonium or any other traditional emulsifier for bitumens.

 The emulsion also preferably comprises a light oil ensuring a better interface between the material to be agglomerated and the binder. These light oils are generally distillates, in particular aromatic, of petroleum products. Among these light oils, there may be mentioned coal oil, obtained from distillation between 170 and 3000C or petroleum oil, obtained from distillation between 170 and 3500C, corresponding tars.

 It is also possible to use the distillate obtained by the process described in French patent 2,510,133, which is in particular an aromatic oil obtained by distillation under a pressure of 8 kPa at 310 "C.

 All these oils are also called fluxing oil because they allow the fluidization of bitumen.

 According to a variant of the invention, the cationic inverse emulsion is formed by mixing the light oil then, with stirring, cationic emulsifier of the amine diamine or polyamine type then of a mineral or organic acid and finally of water . The mixture is then introduced at the same time as the binder in an industrial emulsifier.

According to a preferred embodiment of the process according to the invention, the cationic reverse emulsion is formed by weight of
- 0.5 to 5% of emulsifying system,
- 45 to 80% of binder,
- 10 to 40% water,
- 0 to 10% fluxing oil.

More preferably, the cationic inverse emulsion is formed by weight of
- 1 to 4% of emulsifying system,
- 50 to 75% of binder,
- 15 to 40% of water,
- 1 to 8% fluxing oil.

 The emulsion obtained is a dispersion of an aqueous phase in an oily phase such as bitumen or any other equivalent hydrocarbon.

 The cationic direct emulsion suitable for the process according to the invention is well known to those skilled in the art and is generally formed from the cationic emulsifying system indicated above for the reverse emulsion.

 It is also possible to use a cationic emulsion as described in French patent No. 2,175,610.

Preferably, the direct cationic emulsion will be formed by weight of
- 45 to 80% of binder,
- 0.5 to 5% of emulsifier,
- 10 to 40% water,
- 0 to 10% fluxing oil.

 According to one embodiment of the process, in a tank fitted with an agitator, a coal oil or an aromatic petroleum oil is introduced, the initial distillation point of which is between 150 and 220 "C and the end point between 300 and 5000C, this oil is added with stirring cationic emulsifiers of the amine, diamine or polyamine type, then a mineral or organic acid and finally water (the emulsifier can also be an amido-amine, an imidazoline, quaternary ammonium or any other traditional bitumen emulsifier). After stirring, the mixture is introduced at the same time as the binder in an industrial emulsifier. The emulsion obtained which is a dispersion of an aqueous phase in the bitumen is then mixed in a tank with a conventional cationic bitumen emulsion to give the final emulsion according to the invention.

 Preferably, between 10 and 40% by weight of reverse emulsion and 60 and 90% of the emulsion described are mixed, advantageously 15 and 35%, 65 and 85% respectively.

 The mixture of the two emulsions is then introduced into a mixer containing a mixture of crushed material, the particle size curve of which can be between 0 and 20 mm, 0 and 6 mm, 0 and 10 mm, 0 and 14 mm, as the case may be.

 After a determined mixing time generally of the order of 1 to 2 min, all the surfaces of the materials are coated and the mixture remains manipulated for several days.

 According to a preferred variant, 2 to 20 parts of the binder emulsion are introduced per 100 parts of crushed material.

 The subject of the invention is also a binder emulsion resulting from the mixing of a water-in-oil reverse emulsion of said binder and of a direct oil-in-water emulsion of said binder, as defined above, intended in particular for coating '' a crushed material.

 The subject of the invention is also the coated materials obtained by the process described above.

These materials have the following qualities - storage for several days, - no loss of water, - easy installation by mechanical means (finisher, grader) or
manual, - connection with the under layers, without a bonding layer, - no creep or rutting under traffic.

 The invention will now be described by embodiments as set out below.

According to a general mode of preparation of the binder emulsion common to all the examples below, the production of the emulsion is carried out as follows
In a tank fitted with an agitator, a coal oil or an aromatic petroleum oil is introduced, this oil is added with stirring cationic emulsifiers, then a mineral or organic acid and finally water. After stirring, the mixture is introduced at the same time as the binder in an industrial emulsifier. The emulsion obtained which is a dispersion of an aqueous phase in the bitumen is then mixed in a tank with a conventional cationic emulsion of bitumen to give the final emulsion according to the invention. The mixture is then introduced into a mixer containing a mixture of crushed materials.

Example I
In a container fitted with an agitator, mix in order
64 kg of a distillation coal oil between 170 "C and 300" C,
6 kg of a copra amine,
6 kg of a propylene tallow diamine,
5 kg of glacial acetic acid,
270 kg of water.

 The mixture is heated to 40 "C then it is introduced into another container also equipped with an agitator and containing 650 kg of a binder consisting of a mixture of fluid bitumen (" cut back ") and bitumen. The mixture is heated to 130 ° C. for an appropriate time.

 The reverse emulsion obtained contains 27% water, 73% binder and 2% emulsifying system.

 The emulsion obtained is mixed with a direct cationic bitumen emulsion having a siliceous filler test of 120, a pH of 4 and a binder content of 60%. The proportion of the mixture is 23% for the reverse emulsion and 77% for the traditional emulsion.

 7 parts by weight of the final mixture are introduced into a mixer containing 100 parts of a mixture of crushed materials, 6% of which pass through an 80 micron sieve and 100% through a 6.3 mm sieve. After 30 seconds of mixing all the surfaces of the materials are coated and the mixture remains manipulated for several days.

Example II
This example is identical to Example I, except that the coal oil is replaced by a petroleum distillation oil from 170 ° C. to 350 ° C.

Example III
This example is identical to Example I, except that acetic acid is replaced by hydrochloric acid.

Example IV
This example is identical to Example I, but the crushed material has a particle size which ranges from 0 to 20 mm.

Example V
This example is identical to Example I except that the conventional bitumen emulsion is replaced by a modified bitumen emulsion, as described in French patent 72 09118.

 The materials obtained according to these examples have the properties as indicated in the description.

Claims (11)

 1. A method of coating a material, in particular a material crushed from massive rocks or alluvial rocks, with a binder, consisting in bringing said binder into contact with said material in a kneader, characterized in that the binder is under the form of an emulsion, said emulsion being obtained by mixing a reverse water-in-oil emulsion of said binder and a direct oil-in-water emulsion of said binder.  2. Method according to claim 1, characterized in that the reverse emulsion is of the cationic type.  3. Method according to claim 2, characterized in that the cationic reverse emulsion is formed by weight of  - 0.5 to 5% of emulsifying system,  - 45 to 80% of binder,  - 10 to 40% water,  - 0 to 10% fluxing oil.  4. Method according to claim 3, characterized in that the cationic reverse emulsion is formed by weight of  - 1 to 4% of emulsifying system,  - 50 to 75% of binder,  - 15 to 40% of water,  - 1 to 8% of fixing oil.  5. Method according to one of claims 1 to 4, characterized in that the emulsifying system is formed of one or more cationic surfactants having amine groups and one or more acidic compounds making it possible to yield a proton.  6. Method according to claim 1, characterized in that the direct emulsion is a cationic emulsion, preferably formed by weight of  - 45 to 80% of binder,  - 0.5 to 5% of emulsifier,  - 10 to 40% water,  - 0 to 10% fluxing oil.  7. Method according to one of the preceding claims, characterized in that the binder is bitumen.  8. Method according to one of claims 1 to 7, characterized in that 10 to 40% of reverse emulsion and 60 to 90% of direct emulsion by weight are mixed.  9. Method according to one of the preceding claims, characterized in that the mixture of the two emulsions is introduced into a mixer containing a mixture of crushed materials whose particle size curve is between 0 and 20 mm.  10. Binder emulsion as defined in claims 1 to 8, intended in particular to implement the method of one of claims 1 to 9.  11. Coated material obtained by the method of one of claims 1 to 9.