EP0360695B1 - Process for the in situ production of a road membrane reinforced with fibres obtained by cutting threads - Google Patents

Abstract

The process used in road engineering comprising the laying of a layer of binding material, possibly the interposition of a base course and finally the laying of a road carpet in the form of a carpet of coated materials is characterised, according to the invention, in that fibres are thrown onto and/or into the binding material which are obtained by cutting threads in situ and which form the reinforcement of the membrane, and at the same time the laying of the layer of binding material is carried out.

Description

The present invention relates to a method of in situ manufacturing of a reinforced road membrane by projection of fibers obtained by cutting wires.

The invention relates in particular to the repair of cracked roads and pavements, but also applies to the construction of new pavements.

Traditionally, the repair of roads that are cracked or liable to crack (semi-rigid pavements) is carried out by depositing a thick layer of asphalt with a high content of bituminous binder. These mixes are generally produced in a central plant and applied using a finisher.

According to another technique, a bituminous mortar composed essentially of sand, a bituminous binder and fines, is interposed between the cracked layer and the wearing course - made up of a mix or a coating - about 1 to 3 cm.

It is also known to use a surface layer or an intermediate layer consisting of a very thick bituminous binder and studded with aggregates (cf. for example FR-A-2 231 815).

According to a more recent technique, a prefabricated geotextile is interposed between the cracked layer and the wearing course, possibly with a binder. However, these materials present many difficulties because it is not obvious to unwind satisfactorily rolls of geotextiles and to lay the sheets whose recovery is difficult to succeed. In addition, this system adapts very poorly to the geometry of the road and the support; there are folds in the curves and changes in slope, which affect the efficiency of the complex.

GB-A-802 623 describes the introduction of synthetic filamentary materials - fibers or fabrics - into bituminous mixtures to serve as a reinforcement for wearing courses.

GB-A-2 081 603 and the corresponding article "Technology today" in International Construction, 22 no. 9, Sept. 1983, 12, relate to the spraying of a binder reinforced with glass fibers on a substrate such as a concrete surface.

EP-A-0 356 284 of the present Applicant relates to a method of building roads comprising the projection onto a layer of binder of a continuous wire serving as reinforcement.

We have now found a process for the construction or repair of roads and pavements, efficient and usable at the desired scale, by creating - in situ - a road reinforcement in a bituminous binder.

• a) d'éviter, sur des chaussées fissurées, la remontée des fissures à travers un tapis de roulement, tout en restant pour ce dernier, dans un complexe d'épaisseur faible;
• b) d'augmenter dans tout revêtement routier sa résistance en fatigue face à la répétition des sollicitations, tout en conservant les niveaux de module (rigidité) les plus élevés; et
• c) d'améliorer l'étanchéité d'un ouvrage d'art.

The object of the invention is therefore:

• a) to avoid, on cracked pavements, the rise of cracks through a treadmill, while remaining for the latter, in a thin complex;
• b) increase in any road surface its resistance to fatigue in the face of repeated stresses, while retaining the highest levels of modulus (rigidity); and
• c) improve the watertightness of a structure.

The invention relates to a method of in situ manufacturing of a reinforced road membrane, comprising the installation of a binder layer, possibly the interposition of a base or bonding layer and finally the installation of a layer. of rolling in the form of a coating of asphalt, characterized in that synthetic fibers obtained by in situ cutting of wires during their projection are projected onto and / or into the binder, these wires forming the reinforcement of the membrane, and the establishment of the binder layer is simultaneously carried out.

If necessary, the road membrane thus formed is covered with a layer of aggregates or a prefabricated lattice, possibly with a second layer of binder, before the establishment of the following layer or layers.

The binder used is in particular a binder modified by a polymer such as a “bitumen-polymer”, which can be fluxed or fluidized, and it can be applied using usual materials (for example with a spreader) either hot or cold in the form of an emulsion, at a rate of 0.2 to 4 kg / m², preferably 0.6 to 1.2 kg / m² of residual binder.

The synthetic fibers used according to the invention can be organic or mineral fibers, treated or not, for example polyester, polyamide, polypropylene or cellulose derivatives. Polyester or polyamide fibers are preferred. Their length can range in particular from 0.5 to 8 cm, preferably from 1 to 4 cm. They are obtained by in situ cutting (chopping) of single or multi-strand wires. The grade of these threads can vary over a wide range from 80 to 5000 decitex, preferably from 150 to 400 decitex. According to the invention, 30 to 400 g / m² of fibers will be used, preferably 40 to 120 g / m². The fibers projected at high speed onto and / or into the binder form with the latter, in the final road complex, a tight reinforced membrane. The projection can be carried out for example by means of compressed-air chopper guns or any other device of this type. As said above, the binder and the fibers will be sprayed simultaneously.

In order to be able to circulate on the membrane thus formed to then produce the wearing course covering the latter, it is preferable to spread over the surface a clear grid of aggregates. This will generally be formed of gravel (for example 6/10 mm), spread at a rate of 2 to 10 l / m², for example about 5 l / m², but other particle sizes and dosages are possible. These aggregates do not need to be rolled. It is also possible to use a prefabricated lattice, in particular a metallic or polypropylene lattice. In some in this case a second layer of binder can be applied.

The wearing course is carried out in the usual way, possibly with prior interposition of a base or bonding layer according to current techniques.

Thanks to the use of relatively long fibers, a three-dimensional network of entangled fibers is obtained according to the invention, forming a reinforcement improving the performance of the coating.

The following example illustrates the invention.

EXAMPLE: Repair of a very cracked road due to lack of structure.

An SBS bitumen-polymer emulsion (such as Neolastic ^R manufactured by the company SCREG RTP) is used by spraying at a rate of 1.2 kg / m² (ie approximately 0.8 kg / m² of residual binder).

Polyamide fibers are obtained simultaneously with this binder, obtained from 1400 decitex yarns of 68 strands each (supplied by the company Rhône-Poulenc), chopped in situ into strands having an average length of approximately 1.5 cm, at 50 g / m², using a compressed air chopper gun, so as to obtain a reinforced membrane.

Then spread a 6/10 gravel at a rate of 5 l / m².

Finally, the wearing course is carried out by using a traditional mix (0/10 bituminous concrete) at the paver at the rate of 80 kg / m².

By way of comparison, on the same section, a carpet of the same coated material as above was spread, dosed at 120 kg / m². After putting into circulation, the cracks in the support began to reappear, unlike the reinforced board obtained above according to the invention.

Claims (9)

1. Process for manufacturing, in situ, a reinforced road membrane, comprising the application of a binder layer, possibly with interposition of a base or bonding layer, and finally the application of a surfacing in the form of a carpet of bituminous mixes characterised in that there are projected, onto and/or into the binder layer, synthetic fibres obtained by cutting up yarns in situ during their projection, these yarns forming the reinforcement of the membrane and in that the application of the binder layer and the projection of fibres onto and/or into the latter are carried out simultaneously.
2. Process according to Claim 1, characterised in that the binder is applied at a rate of 0.2 to 4 kg/m².
3. Process according to Claim 2, characterised in that the binder is a binder modified by a polymer and it is applied at a rate of 0.6 to 1.2 kg/m² of residual binder.
4. Process according to any one of Claims 1 to 3, characterised in that 30 to 400 g/m² of fibres are used.
5. Process according to Claim 4, characterised in that 40 to 120 g/m² of fibres are used.
6. Process according to any one of Claims 1 to 5, characterised in that the fibres have a length of 0.5 to 8 cm.
7. Process according to Claim 6, characterised in that the fibres have a length of 1 to 4 cm.
8. Process according to any one of Claims 1 to 7, characterised in that the road membrane is covered with a layer of aggregate or with a mesh.
9. Process according to Claim 8, characterised in that the layer of aggregate is spread out at a rate of 2 to 10 l/m².