EP3987116B1 - Road surfacing reinforcement of the cold surface dressing type and method for producing road surfacing using such a reinforcement - Google Patents

Description

Technical area

The invention relates to the field of fibrous reinforcements used in the construction and maintenance of roads.

The invention relates in particular to a road surface reinforcement of the cold surface coating type.

The invention finds a particularly advantageous application for the reinforcement of road pavements, in particular for improving their resistance to the propagation of cracks.

Technology background

• un sol support ;
• un terrassement constitué d'une ou plusieurs couches de matériaux non traités dites couches de fondation ; et
• une couche de revêtement constituée d'une succession de couches de matériaux traités.

Conventionally, a road structure consists of a succession of layers comprising in particular:

• a support floor;
• earthwork consisting of one or more layers of untreated materials called foundation layers; And
• a coating layer consisting of a succession of layers of treated materials.

There are mainly three types of bitumen surfacing layers, namely asphalt and cold or hot plaster.

Asphalt is a mixture of aggregates and binder, manufactured in the factory, applied in a single layer on the site. They are generally applied hot, that is to say at temperatures between 120 and 170°C.

Hot surface dressings are formed directly on site by at least two superimposed layers: a layer of fluxed bitumen and a layer of aggregates. It is also possible to repeat the operation so as to obtain a two-layer coating or three-layer... Hot surface coatings are applied at temperatures of the order of 160°C.

Cold surface coatings are also formed directly on site by at least two superposed layers: a layer of bonding binder, typically a bitumen emulsion or a bitumen thinned with solvent or other, and a layer of aggregates. It is also possible to repeat the operation so as to obtain a two-layer or three-layer coating. Cold surface dressings are generally applied at temperatures between 50 and 60°C.

The invention relates specifically to this last type of coating layer.

It is common to observe cracks on the roads or departures of pothole-type materials. These degradations appear in particular with wear related to traffic, temperature variations or oxidation by UV rays. However, these damages can lead to traffic disruption or even accidents for motorists. To fight against these phenomena of pavement cracking and departure of materials, it is necessary to resort to repair techniques. The same is true for certain pavements in order to improve their impermeability.

Among these techniques, one solution consists of pouring a new layer of cold surface dressing. However, the layers of cold surface dressing are often thin and subject to rapid wear, which leads to the rapid reappearance of surface cracks and the decohesion of the aggregates.

Solutions based on textile technologies are thus widely used with the aim of reinforcing the cold surface coating layer and making it more resistant to the propagation of cracks.

By way of example, mention may be made of synthetic geotextiles based on polypropylene, synthetic or mineral geogrids of the fiberglass or polyester fiber type, of carbon fibers or of polyvinyl acetate (PVA) fibers.

The document US 6,315,499 describes a geotextile consisting of a grid made from rovings of glass with a high modulus of elasticity, from 6 to 28 GPa, impregnated with a resin of the PVC type. However, the implementation of this type of geotextile is difficult, in particular on irregular supports, because of its stiffness. In addition, these geotextiles are inextensible, which complicates their installation and their unrolling on the ground, in particular in bends.

The glass mats of the TruPave ^® brand, marketed by the company Owens Corning, are also known. These mats are nonwovens made of high tenacity glass and polyester fibers bonded together. Although having the capacity to slow down the propagation of cracks thanks to the bitumen which impregnates them, the fibers constituting these mats are bonded together and do not allow the fibers which constitute them to mix with the bituminous materials applied over them. In addition, these mats, due to the bonding of the fibers between them, are difficult to implement in bends because they have low elongation and do not withstand deformations well.

The document EP 1 693 517 describes a reinforcement intended for asphalt. The reinforcement consists of an impermeable support covered with a mat of high tenacity fibers. The support is made of a material that is fusible at temperatures of the order of 100°C. Thus, when laying an asphalt mix, the temperatures involved (from 120 to 170°C) are sufficient to allow the support to melt so that the fibers can soak up the mixture of aggregates and binder. constituting the coating.

However, such a reinforcement is not suitable for the technique of cold surface coatings, which involves low temperatures, insufficient to melt the impermeable support. Thus, the support does not allow the fibers of the mat to become impregnated with the bonding layer of a cold surface coating. This has the effect of making impossible to bond the different layers of the cold surface coating. The coating is thus weakened and does not effectively reduce the propagation of cracks and the decohesion of the aggregates.

The technical problem that the invention proposes to solve is to develop a textile reinforcement as well as an associated road reinforcement process, adapted to the technique of cold surface coatings and making it possible to facilitate the laying of the reinforcement on the ground, especially on bends.

Disclosure of Invention

In order to solve the problem set out above, the Applicant has developed a road surface reinforcement of the cold surface coating type comprising at least one layer of bonding binder and one layer of aggregates. Such a reinforcement is intended to be deposited on the layer of bonding binder.

• un support de type voile comportant des fibres synthétiques en polyoléfines non tissées, ce support de type voile étant également perméable au liant d'accrochage ; et
• un mat constitué de fibres à haute ténacité, ces fibres étant destinées à recevoir la couche de granulats ;

Un tel renfort est également caractérisé en ce qu'il est dépourvu de moyens d'accroche du mat sur le support.Such a reinforcement is characterized in that it comprises:

• a veil-type support comprising synthetic fibers made of non-woven polyolefins, this veil-type support also being permeable to the bonding binder; And
• a mat consisting of high tenacity fibers, these fibers being intended to receive the layer of aggregates;

Such a reinforcement is also characterized in that it has no means for attaching the mat to the support.

Within the meaning of the invention, a mat is defined as being a material consisting of randomly dispersed mineral fibers. The latter having no means of attachment between them.

The veil type support is defined as a synthetic fabric, consisting of fibers made of polyolefin, for example polypropylene, polyester or other synthetic material which can be light, that is to say, from 2 to 30 g / m ² , deformable and permeable.

The permeability criterion translates into imbibition in a few seconds, at worst a few tens of seconds, of the veil-type support when it is deposited on a layer of fluid, for example a layer of bituminous binder in the form of an emulsion.

The "high tenacity" criterion corresponds to a resistance greater than 70 GPa minimum.

In other words, the Applicant has developed a reinforcement composed of two layers which are not bonded together. The first layer forms a support for the mat which itself consists of fibers to improve the mechanical strength of roads.

Thus, the reinforcement obtained is more flexible than the reinforcements of the state of the art and allows easier unrolling on the road and in bends, without observing the formation of folds. In addition, the permeability of the support allows the bonding layer of the cold plaster to pass through the support to impregnate the fibers and the layer of aggregate deposited on the reinforcement. In particular, this permeability allows the different layers of the cold coating to be bonded to each other while having an elastic nature and resistant to mechanical stress and wear.

Finally, this reinforcement also constitutes a more economical and simpler solution in terms of implementation, compared to existing solutions.

According to one characteristic of the invention, the fibers constituting the mat are selected from the group comprising carbon fibers, basalt fibers, glass fibers.

Preferably, fiberglass is chosen because of its ease of cutting (during the manufacture of the mat) and because of its low cost price. Glass fibers are also renowned for having good adaptability to any climate with increased resistance to high temperatures and good stability with an elongation at break suitable for this use.

Preferably, the fibers are cut. In particular, the fibers constituting the mat have a length of between 10 mm and 300 mm.

According to a first embodiment of the invention, the mat is composed of a single type of fiber of a predetermined length comprised in the length interval stated above.

According to another embodiment of the invention, the mat comprises at least two types of fibers. The fibers of the first type have a length comprised between 7 mm and 50 mm and the fibers of the second type have a length comprised between 10 and 200 mm.

Advantageously, the length of the first type of fiber is between 7 mm and 50 mm, preferentially between 10 mm and 40 mm and the length of the second type of fiber is between 20 and 150 mm, preferentially close to 100 mm.

The shorter fibers deform more easily and penetrate better inside the layer of aggregate deposited on the mat, in particular during compaction. They provide support between the aggregates and thus reinforce the layer of aggregates.

The longer fibers remain at the interface between the bonding binder layer and the layer of aggregates and make it possible to reinforce the hold between the layers. Moreover, the long fibers also make it possible to avoid any discontinuity in the transmission of the stresses, which contributes to a better fatigue resistance of the road structures.

In order to facilitate the flow of the bonding agent through the reinforcement, the support is presented as an open fabric, having an openwork and light structure. In particular, the sail-type support has a surface weight of at most 20 g/m ² .

In the same way, the mat has a surface mass of between 40 and 300 g/m ² , advantageously between 50 and 200 g/m ² , preferentially between 50 and 120 g/m ² .

Indeed, like the veil-type support, the mast forms a very openwork structure, allowing the passage of aggregates in certain places.

Advantageously, the glass fibers have a diameter of between 12 and 50 μm, preferably between 15 and 30 μm; and have a length of between 10 and 500mm, preferably between 20 and 200mm.

In practice, such a reinforcement is packaged in the form of rolls. These are then unrolled on a road structure to be repaired or built. When laying the reinforcement, the openings present in the mat and the fineness of the support, combined with its permeability, make it possible to ensure direct contact between the layer of bonding binder and the layer of aggregate. Thus, the reinforcement is positioned at the interface between the layers of the coating and makes it possible to transmit the forces to which the structure is subjected without causing cracks.

• application d'une couche liant d'accrochage au-dessus d'une chaussée préexistante ;
• déroulage d'au moins un rouleau de renfort selon l'invention, et dépôt du renfort sur la couche de liant d'accrochage de sorte à ce que le renfort s'imprègne de la couche de liant ;
• dépôt sur le renfort d'une couche de granulats;

application d'une pression sur la couche de granulats de sorte à déformer la surface du renfort.The invention thus relates to a process for the manufacture of a road surface of the cold coat type. The process comprises the following steps:

• application of a tack coat over a pre-existing pavement;
• unrolling at least one reinforcement roll according to the invention, and depositing the reinforcement on the bonding binder layer so that the reinforcement becomes impregnated with the binder layer;
• deposition on the reinforcement of a layer of aggregates;

application of pressure on the layer of aggregates so as to deform the surface of the reinforcement.

According to one embodiment of the method, at least two rolls of reinforcements are staggered to be unrolled, in order to preserve a minimum space, ideally zero, or even a slight overlap between two adjacent strips of reinforcement, in order to create continuity. reinforcement across the width of the roadway.

In practice, the reinforcement rolls have a width of 0.50 m to 4 m. The staggered unrolling thus makes it possible to lay the reinforcement in bends without creating folds.

In practice, an unwinder is fitted to a spreader. The rolls are fixed on unwinding bars. The spreader can thus simultaneously apply the bonding binder and the reinforcement, object of the invention.

• application d'une seconde couche de liant d'accrochage ; et
• application d'une seconde couche de granulats sur ladite seconde couche de liant d'accrochage.

According to another embodiment, the method further comprises the following steps:

• application of a second coat of bonding agent; And
• application of a second layer of aggregates on said second layer of tack binder.

Such an embodiment is called multilayer cold plaster and makes it possible to increase the thickness of the cold plaster and consequently its resistance to wear.

• application d'une couche supplémentaire de liant d'accrochage ; et
• par-dessus, application d'au moins une couche de matériaux liés à froid ou à chaud.

According to another embodiment, the method further comprises the following steps:

• application of an additional layer of tack coat; And
• above, application of at least one layer of cold or hot bonded materials.

In other words, the coating can consist of one or more layers integrating the fibrous reinforcement according to the invention, and include additional layers of various materials, either identical to that of the lower layers, or different, or a mixture of the two.

Brief description of the figures

• La figure 1 est une représentation schématique en vue du dessus d'un renfort selon un premier mode de réalisation de l'invention ;
• La figure 2a est une vue schématique en coupe d'un enduit superficiel à froid monocouche avant compactage comportant un renfort de la figure 1 ;
• La figure 2b est une vue schématique en coupe d'un enduit superficiel à froid comportant un renfort de la figure 1 et une couche supérieure, après compactage;
• La figure 3 est une représentation schématique du procédé de fabrication du renfort selon un mode de réalisation de l'invention ; et
• La figure 4 est une représentation schématique de la mise en oeuvre du procédé d'application de l'émulsion et du déroulage du produit de la figure 1 lors de la fabrication d'un revêtement routier de type enduit superficiel à froid, selon un mode de réalisation de l'invention.

The manner of carrying out the invention, as well as the advantages which result therefrom, will clearly emerge from the description of the embodiments which follow, with the support of the appended figures in which:

• There figure 1 is a schematic representation in top view of a reinforcement according to a first embodiment of the invention;
• There figure 2a is a schematic sectional view of a single-layer cold surface dressing before compaction comprising a reinforcement of the figure 1 ;
• There figure 2b is a schematic sectional view of a cold surface dressing comprising a reinforcement of the figure 1 and a top layer, after compaction;
• There picture 3 is a schematic representation of the process for manufacturing the reinforcement according to one embodiment of the invention; And
• There figure 4 is a schematic representation of the implementation of the process for applying the emulsion and unrolling the product of the figure 1 during the manufacture of a road surface of the cold surface coating type, according to one embodiment of the invention.

detailed description

With reference to the figure 1 , the reinforcement 10 is composed of a veil-type support 11, on which is deposited a mat 13.

More specifically, the support 11 of the synthetic nonwoven web type is made of polyolefin fibers, for example polypropylene. By way of example, the web can have a surface weight of 12 g/m ² .

On this veil 11, a mat 13 is formed by a stack of glass threads 12 with a title of 2400 tex cut out and randomly distributed over a thickness of between 0.2 and 5 mm. Each mat fiber is approximately 17µm in diameter. For example, the length of the cut fibers 12 can be 50 or 100 mm for a surface weight of 90 g/m ² .

With reference to the figure 2a , a layer of bonding agent 4 is deposited on a floor to be repaired or more generally where it is necessary to improve the surface layer 2. The floor 2 generally consists of granular materials glued with bitumen or cement or else granular materials linked together. The floor 2 also has an irregular appearance with cracks or potholes on the surface. Alternatively, the bonding layer 4 is deposited on an earthwork or a track to form a new roadway. In this case, the ground 2 to be covered may also have the normal irregularities of unbound earthwork materials.

The reinforcement 10 is deposited on the bonding binder layer 4. The reinforcement 10 is thus pressed against the ground 2 and does not fly away. A layer of aggregates 3 is then applied to the reinforcement 10.

With reference to the figure 2b , the permeability of the veil-type support allows the reinforcement 10 to adopt a three-dimensional configuration and to become impregnated in a few seconds to a few tens of seconds with the layer of bonding binder 4. The reinforcement 10 then becomes transparent and the layer of adhesion binder 4 rises by capillarity at the level of the upper face of the reinforcement 10, in particular during compaction. The reinforcement 10 and the layer of aggregates 3 are partly embedded in the layer of bonding binder 4.

A top layer 5 is then applied to the aggregates 3. This top layer 5 may correspond to a second layer of tack binder and aggregates or to a layer of asphalt or any other top layer of road surfacing.

With reference to the picture 3 , a process for producing the reinforcement can be implemented in the factory or directly in situ, during the repair of the road.

In the first case, the reinforcement 10 is produced by causing the web 11 to scroll on a conveyor 16, directly below which there is a cutting unit 17, formed for example facing cylinders, at least one of which is equipped with cutting elements. This cutting unit is fed by one or more glass thread(s) and generates thread segments 12, which fall randomly on the veil 11. These segments 12 have a length determined by the configuration of said cylinders, the speed of which makes it possible to adjust the quantity and thickness of threads 12 composing the mat 13.

Alternatively and not shown on the picture 3 , several cutting units 17 configured to each produce wires 12 of a predetermined length can be juxtaposed to produce a mat 13 composed of wires 12 of different lengths.

The cutting methods are known to those skilled in the art. The web 11 on which the mat 13 rests has no means of attachment with the mat 13. The web 11 is then rolled up to form rolls 18. In this way, the mat 13 is clamped between two portions of the web 11 and the wires 12 are not at risk of flying or falling during storage or transport.

The rolls thus formed have a length of between 10 and 500 m and a width which can vary between 30 cm and 4 m depending on the application for which they are intended. For example, in the case of a straight road without turns, a single roller of the width of the road can be used. On the contrary, if the road has many bends, the juxtaposition of several rolls of smaller width makes it possible to better understand the homogeneous distribution of the fibers in the layer of cold coating.

Once produced, the rolls are then transported and then unrolled on the pavement site to be repaired or covered.

With reference to the figure 4 , a method of manufacturing a road surface can be implemented on a new pavement or a pre-existing pavement.

A first layer of bonding binder is deposited by means of an emulsion spreader 40 projecting the binder via a ramp of spray nozzles 41.

A tack coat is typically a bitumen emulsion composed of 65% to 69% bitumen to 31 to 35% water and also contains adjuvants. The binder layer is deposited so as to obtain a surface mass of approximately 1100 g/m ² .

The rear of the spreader 40 is equipped with a frame comprising reels on which are installed rollers 18 of reinforcement. The number and position of the reels is determined to allow the removal of several reinforcements, over the total width of the road, in parallel side-by-side or with an overlap between the rollers 18. The frame can adopt two positions: a position bottom allowing the reinforcement to be unrolled and an upper part allowing other tasks to be carried out such as moving the spreader 40 from its storage location to the site.

Preferably, the reels are staggered, so that the adjacent reinforcements overlap to ensure continuity of coverage. The reels are preferably independent, so as to allow a difference in length deposited in bends, between the inside and the outside of the curve.

Preferably, the reels are positioned and reeled as close as possible to the ground, typically against the ground, to allow the reinforcement not to be deformed under the effect of gravity and wind, and also to allow the reinforcement to soak up quickly from the tack coat before it fails or dries. Alternatively, the rolls can be unrolled by hand applying the same precautions as those mentioned above. In some cases, the reinforcement can be unrolled, with the fibers 12 below and the support 11 above. This creates a bitumen-rich interface reinforced by mat 13.

A layer of aggregates is then deposited on the reinforcement, generally by a grit spreader. The aggregates are generally made of stone and have a diameter between 2 and 15 mm. They are distributed so as to obtain a surface weight layer of approximately 2 kg/m ² to 15 kg/m ² .

The layers are then compacted by a compactor, to allow the tackifier to impregnate the upper layers and the reinforcement to deform to adopt the topology of the road. A second layer of emulsion is then deposited on the layer of aggregates.

The process can then be repeated so as to form two-layer or three-layer cold plasters therefore including several fibrous reinforcements. It is also possible to deposit other layers of materials (without fibrous reinforcement) on top of the layer or layers including the fibrous reinforcement or reinforcements.

In conclusion, this reinforcement makes it possible to transmit the forces to which the road structure is subjected and to obtain a better resistance to cracking and to the disintegration of the aggregates. Such a reinforcement also constitutes a durable, economical and simpler alternative to implement than the existing solutions for reinforcing the coating of road pavements.

Claims (10)

1. A road surfacing reinforcement (10) of the cold surface dressing type comprising at least one bonding binder layer (4) and an aggregate layer (3), said reinforcement being intended for being deposited on said bonding binder layer (4), said reinforcement (10) comprising

   - a web-like substrate (11) comprising non-woven polyolefin synthetic fibres; said web-like substrate being permeable to said bonding binder; and

   - a mat (13) consisting of high-tenacity fibres (12); the fibres (12) constituting the mat (13) being selected from the group consisting of carbon fibers, basalt fibers, glass fibers, said fibres (12) being intended for receiving the aggregate layer (3);

   said reinforcement (10) being not provided with means for attaching the mat (13) to the substrate (11).
2. The road surfacing reinforcement according to claim 1, characterised in that the fibres (12) consisting the mat (13) have a length of between 10 mm and 300 mm.
3. The road surfacing reinforcement according to any one of claims 1 or 2 characterised in that the mat (13) comprises at least two types of fibres (12); the fibres of the first type having a length of between 7 mm and 50 mm and in that the fibres of the second type have a length of between 10 and 200 mm.
4. The road surfacing reinforcement according to any one of claims 1 to 3, characterized in that the web-like substrate (11) has a qurface density of at most 20 g/m².
5. The road surfacing reinforcement according to any one of claims 1 to 4, characterized in that the surface density of the mat (13) is between 40 and 300 g/m².
6. The road surfacing reinforcement according to any one of claims 1 to 5, characterised in that the glass fibres (12) have a diameter of between 12 and 50 µm and an average length of between 10 and 500 mm.
7. The road surfacing reinforcement according to any one of claims 1 to 6, characterized in that said reinforcement (10) is packaged in the form of rollers (18).
8. A method for producing a road surfacing of the cold surface dressing type, characterized in that said method comprises the following steps:

   - applying a bonding binder layer (4) over a pre-existing roadway (2);

   - unwinding at least one roller (18) of reinforcement (10) according to claim 7, and

   - depositing said reinforcement (10) on said bonding binder layer (4) such that said reinforcement (10) is impregnated with said binder layer (4);

   - depositing an aggregate layer (3) on said reinforcement (10);

   - applying pressure to the aggregate layer (3) so as to deform the surface of said reinforcement (10).
9. The method for producing a road surfacing according to claim 8, characterised in that at least two rollers (18) of reinforcements (10) are unwound in a staggered manner.
10. The method for producing a road surfacing according to claim 8, characterised in that said method further comprises the following steps:

    - applying an additional bonding binder layer on said aggregate layer; and

    - applying an aggregate or bonded materials layer on said second bonding binder layer.

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