EP2304089B1 - Cloth and reinforcing mesh with the insertion of mineral fibers for civil engineering works - Google Patents

Abstract

The threads, strands, or cords of said lap or said mesh are parallel in at least one direction and are each simultaneously composed of mineral fibers having low elongation (high modulus of elongation under stress) and an elongation at break value of 2 to 5%, and polymer fibers and/or natural origin fibers having a modulus of elongation under stress lower than that of the mineral fibers and an elongation at break value significantly higher than that of said mineral fibers, of 10 to 20%.

Description

TECHNICAL AREA

The present invention relates to a reinforcement ply of geo-synthetic type or a grid for civil engineering applications. This sheet or grid comprises at least one series of parallel reinforcing strands in which strands based on mineral fibers or by-products are introduced. This tablecloth or grid also includes mineral fibers and / or fibers of plant origin in an eco-design approach.

Among the civil engineering applications likely to implement the object of the present invention, mention may be made of reinforcing reinforcement of floors, slopes and embankments as well as grids for reinforcing elements of bitumen grid type structures, grids coated , grids with resins and dies, made especially in the framework of motorway projects, railway constructions, retaining walls, supports and bridge decks, etc.

PRIOR STATE OF THE TECHNIQUE

In the field of civil engineering, reinforcement plies are commonly used to perform the functions of reinforcement or reinforcement of a structure in structural elements subject to stress.

They can be combined with other materials (non-woven, woven, spacer, resins, dies) or coated (PVC, bituminous impregnation or other) to perform several functions such as separation between layers of soil, drainage, filtration , waterproofing or protection of all or part of the work. It may also be retaining layers possibly flush on all or part of their surface and which has a function of vegetation and / or anti-erosion.

These sheets are subject to the rules of the art and construction codes and must ensure longevity and safety of the structures thus composed.

In particular, the quality of the reinforcing plies must allow a maximum of mechanical properties to be preserved during aggressive episodes on the structure either during construction (fresh concrete, mechanical aggression, etc.) or later during the construction phase. life of the structure (infiltration, surrounding chemical environment, geological collapse, abnormal overload ...). In particular, there are cases of excessive temperatures, particular chemical environments, sometimes fire for the flush plies. The polymer-based webs sometimes have insufficient properties for these different cases.

• en utilisation courante, sous un chargement adapté au comportement de l'ouvrage en service, il est souvent essentiel de limiter les déformations de l'ouvrage pour assurer son bon usage. Un matériau présentant une bonne résistance avec un faible niveau de déformation peut avantageusement assurer cette fonction. Les nappes de renfort à base de polymères courants (polyester, polypropylène ou polyéthylène) ne remplissent pas idéalement les conditions nécessaires en termes de déformation en raison d'une déformation initiale trop importante pour des efforts relativement faibles.
• les capacités mécaniques de la nappe utilisée doivent aussi être suffisantes pour reprendre des charges plus importantes à l'échelle de l'ouvrage dans des cas d'usage limite (surcharge exceptionnelle, déformation géologique...).et ainsi éviter la rupture.

The expected properties of these reinforcements are better explained by splitting them into two phases:

• in current use, under a load adapted to the behavior of the structure in use, it is often essential to limit the deformations of the structure to ensure its proper use. A material having a good resistance with a low level of deformation can advantageously provide this function. The reinforcing plies based on current polymers (polyester, polypropylene or polyethylene) do not ideally fulfill the necessary conditions in terms of deformation due to excessive initial deformation for relatively low forces.
• the mechanical capacities of the sheet used must also be sufficient to take on larger loads at the scale of the structure in cases of limited use (exceptional overload, geological deformation ...) and thus avoid breakage.

Despite a design that responds to these extreme situations, the products made of conventional polymers must in fact often be oversized in quantity of material to obtain acceptable deformation, sufficiently low in normal use. The current polymers with limited costs have too much elongation at low stress.

At the level of reinforcement at break, there is also a geosynthetic technique, described for example in the document FR 2,767,344 which includes several separate parallel fiber materials for the same product, advantageously PVA, which has an elongation at break of 5% and at least one other material having an elongation at break of at least 12%. This technique makes it possible to ensure the reinforcement of soils at risk of collapse (Fontis) by a "parachute" effect resulting from this "multi-module".

At a low rate of deformation, all materials actively participate in the recovery of the work. When an overload or a disorder appears, it is absorbed by the PVA material up to 5% of deformation, then beyond, it is the second material which supports the rupture and signals it by a significant deformation but without rupture, and for example, by a rut on a road, materializing the local collapse, leading to its repair.

• ■ allongement insuffisant à la rupture pour assurer la fonction parachute, comme indiqué dans le document précité ;
• ■ complexité de la fabrication des grilles comportant à la fois des fibres minérales et des polymères avec des problèmes de cassure des brins minéraux par frottement et cisaillement dans un circuit prévu pour des polymères ;
• ■ fragilité dans la mise en oeuvre sur chantier où il faut employer un système assurant la protection des fibres de verre dans les sols agressifs sur le plan mécanique pour la fibre.

Mineral fibers (glass, basalt ...) are not used today in these applications for three reasons:

• ■ insufficient elongation at break for parachute function, as indicated in the aforementioned document;
• Complexity of the manufacture of grids comprising both mineral fibers and polymers with problems of breaking mineral strands by friction and shear in a circuit provided for polymers;
• ■ fragility in the implementation on site where it is necessary to use a system ensuring the protection of glass fibers in mechanically aggressive soils for fiber.

The manufacture of the sheet or the grid can only be achieved by a suitable technique, and specific solutions must be applied for the implementation.

SUMMARY OF THE INVENTION

The present invention relates to a reinforcing ply or grid, at least a part of which at least one of at least one parallel son, strand or cabled reinforcement is simultaneously composed of mineral fibers or derivatives thereof (glass, basalt, fiberglass + material complex thermoplastic impregnation (as marketed under the trademark Twintex®) ...), and polymer fibers and / or natural fibers.

In other words, the invention consists in associating, within wires or cords constituting a ply or a grid and extending in the same direction, mineral fibers with a low elongation (elongation module under high tension) and with a value of elongation of rupture of between 2 and 5%, and fibers of polymer type and / or fibers of natural origin having a modulus of elongation under tension lower than that of the mineral fibers and a value of elongation of rupture significantly greater than that of said mineral fibers, and between 10 and 20%.

The distribution of the strands is heterogeneous. In doing so, each wire or cable is composed of two associated materials according to one of the following processes: strands of mineral fibers and of polymer or natural fibers placed in parallel, or twisted or thermally associated while playing on the thermoplastic properties of the fibers used. implemented.

This composition makes it possible to ensure a high-performance mechanical reinforcement meeting the rules of the art, the safety and longevity required in the field of civil engineering.

Thus, thanks to the mineral fibers, a high initial modulus is obtained, that is to say a very small deformation, of the order of 2 to 3% for relatively high stresses, whereas, due to an equivalent rupture, an ordinary organic polymer achieved a deformation two or four times higher (5 to 7% deformation) under the same conditions. This result is combined with polymers conferring a very high resistance with a deformation level of at least 10% by the principle of the multi-module implemented by the invention. This realization is perfectly adapted to the behavior at limit states normalized by the profession,

According to the invention, the mineral fibers may be made of a material selected from the group comprising basalt, and different glass fibers with selected properties such as, for example, glass E, glass S (thermally more resistant), glass R (high module) and AR glass (alkali resistant)

According to the invention, the polymer type fibers may be made of a material selected from the group consisting of polyester, polypropylene and polyethylene.

Still according to the invention, the fibers of natural origin can be made of a material chosen from the group comprising hemp, flax and coconut.

To ensure longevity and optimum quality for a very small deformation in current use, the use of a mineral fiber, advantageously fiberglass, allows its strong resistance under low deformation to take some of the mechanical stresses on the structure or the structural element, to limit its deformations and ensure its stability. This fiber has a clear advantage over this point compared to conventional polymer fibers of the polyester group, polyethylene, polypropylene, especially with the ability to optimize cost and quantity of materials. It also eliminates aramid fibers, a much higher cost, making it incompatible for a large number of applications, because of the extra cost generated.

• résistance mécanique très élevée en traction avec une faible déformation. La résistance d'un verre standard présente une déformation à la rupture de l'ordre de 3% ;
• coût très inférieur aux fibres à faible allongement en traction de type aramide ;
• disponibilité de matière moins problématique ;
• conception respectueuse de l'environnement.

Mineral fibers (glass, basalt ...) have many advantages:

• very high tensile strength with low deformation. The resistance of a standard glass has a breaking strain of about 3%;
• cost much lower than aramid tensile stretch fibers;
• availability of less problematic material;
• eco-friendly design.

Compared to materials, grids and geosynthetics with equivalent mechanical properties, such as products based on aramid fibers, carbon fibers, etc. the reinforcing ply or grid made according to the invention comprising both mineral fibers and organic polymeric fibers and / or natural fibers (hemp, coconut, linen) has a very clear economic advantage because of the cost to purchase and the implementation of this type of materials.

In some cases mechanically aggressive soils, it may be necessary to use a variant arranged in such a way that it allows the protection of mineral fibers against external mechanical attacks that could break them.

In these groups of strands, it is possible to use a fiber of simple mineral material, coated, treated or protected, in particular by a thermoplastic polymer, in the form of a sheath or resulting from an impregnation. Mineral fibers, glass, basalt and derived products have advantageous behaviors, especially in terms of thermal resistance and inertia with respect to chemical reactions. The treated, coated or protected fibers may be used to further improve performance, for example high temperature resistant glass, alkali resistant glass, basalt fibers, and especially the technique of multifilaments mixing glass and a thermoplastic, and such marketed under the trademark Twintex®. The latter technology ensures glass protection and durability. A radiant furnace or other heating system is then integrated at the output or at the heart of the loom on the warp and / or weft feed of the Rachel loom or loom to impregnate the reinforcing mineral fibers with the thermoplastic product.

All these materials with a specific adaptation may be suitable for civil engineering applications requiring long service lives and special situations such as stability during a fire, treated floors, potentially cutting aggregates for mineral materials, the presence of concrete fresh with high pH, etc.

According to a variant of the invention, cellulosic fibers and / or connected fibers or loops are inserted into the sheet or the grid, in order to confer a revegetation and / or anti-erosion function.

BRIEF DESCRIPTION OF THE FIGURES

• La figure 1 est une courbe représentative de la déformation d'une nappe, respectivement réalisée en verre (courbe de gauche) et en polyester (courbe de droite en fonction de la charge appliquée.
• La figure 2 est une courbe représentative de la déformation d'une nappe réalisée conformément à l'invention en fonction de la charge appliquée.
• La figure 3 est une courbe représentative de la déformation d'une nappe réalisée en polyester seul en fonction de la charge appliquée.
• La figure 4 illustre schématiquement une grille vue du dessus conformément à l'invention, dont la figure 5 est une vue en section.

The manner in which the invention can be realized and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, given as an indication and without being limiting, in support of the appended figures.

• The figure 1 is a curve representative of the deformation of a sheet, respectively made of glass (left curve) and polyester (right curve depending on the applied load.
• The figure 2 is a curve representative of the deformation of a web made according to the invention as a function of the applied load.
• The figure 3 is a curve representative of the deformation of a sheet made of polyester alone as a function of the applied load.
• The figure 4 schematically illustrates a grid viewed from above according to the invention, the figure 5 is a sectional view.

EMBODIMENT OF THE INVENTION

The figure 1 illustrates the tensile curve of two plies, two separate materials (glass and PET) which thus selected may allow the embodiment of the invention with a economically advantageous behavior in terms of the amount of glass relative to the amount of polyester. We see on this figure 1 that for an equivalent effort, the deformation of the sheet made of glass is significantly lower than that of the sheet made of polyester. Thus, for a load or effort of 80 KN, the deformation of the glass is of the order of 2% whereas that of the polyester is already 6%.

The figure 2 illustrates the behavior of a web made according to the invention with simultaneous use of the two types of fibers, respectively polyester and glass. At the beginning of the submission to the efforts, that is to say in normal use, it is mainly the glass which ensures the resistance with a very small deformation. If these efforts become higher, the rupture of the glass occurs precisely because of its small deformation, said rupture being materialized on the curve by the first point of inflection, but the polyester then takes over, materialized on the curve by the second point of inflection.

The curve represented on the figure 3 shows that it would be possible to obtain the initial stiffness with polyester alone, but with a much greater weight of polyester, whose breaking strength would be much higher than 450 KN (top curve) while a total resistance 145 KN was needed in this example. (bottom curve).

• La figure 4 illustre la réalisation et la disposition de câblés conformes à l'invention. En l'espèce, chacun des câblés (40), selon au moins l'une des directions, associe les deux matières (41) (fibres de verre ou de basalte) et (42) (fibres de polyester haute ténacité ou fibres naturelles). Ces câblés sont, dans l'exemple décrit, juxtaposés sur une nappe (43) en non tissé ou tissé ou composée de plusieurs couches, et/ou sur des fils de trames (45), par exemple réalisée en polyester (sur la figure 4) ou également en câblés de même structure (figure 5). Les techniques d'association des câblés ou fibres sur une nappe ou/et sur des fils de trames par machine de tissage ou métier Rachel trameur sont largement connues, de sorte qu'il n'y a pas lieu de les décrire ici plus en détail. On a simplement matérialisé par la référence (44), les fils de liage des câblés (40) sur la nappe (43) et les fils de trame (45).
• La figure 5 est une représentation schématique en section de la figure 4, et qui permet de mieux distinguer cette structure.

It is understood that the cost of the solution according to the invention is very interesting since it avoids using about three times more material. This surplus is replaced by a mineral fiber at very low cost

• The figure 4 illustrates the construction and layout of cords according to the invention. In the present case, each of the cords (40), in at least one of the directions, combines the two materials (41) (glass or basalt fibers) and (42) (high tenacity polyester fibers or natural fibers) . These cords are, in the example described, juxtaposed on a web (43) non-woven or woven or composed of several layers, and / or on son of frames (45), for example made of polyester (on the figure 4 ) or also in cords of the same structure ( figure 5 ). The techniques for associating cords or fibers on a web or / and on weaving machine son or Rachel loom thread are widely known, so that there is no need to describe them here in more detail . It was simply materialized by the reference (44), the wiring son of the cords (40) on the web (43) and the weft son (45).
• The figure 5 is a schematic representation in section of the figure 4 , and which allows to better distinguish this structure.

The fibers, respectively mineral (41) and polymeric or natural (42) are associated within the aforementioned cords (40), for example by twisting or twisting or parallel insertion. In addition, these cords are optionally coated with a thermoplastic protection for example, after passage to heat, and this before assembly (Mineral fibers sheathed thermoplastic material, and for example polyester), or after assembly (OWENS CORNING technology for the realization of Twintex® type cords).

According to the invention, the multi-component web or grid can be made on the looms usually used for the production of webs (such as the DORMIER or SULZER looms), or by the chain and Rachel technology (type loom). Karl Mayer or Liba for example) with or without insertion of frames. These technologies make it possible to work with mineral fibers, such as glass or basalt, without altering the fiber, in particular mechanically, and while producing complex structures and meshes including many other materials.

The looms can work according to conventional weave armor or in a type of gauze armor allowing a lower embossing reinforcing fibers by using fine binding son.

The Rachel technology also allows the realization of multifunction products with insertion of separation sheets, (non-woven or woven or composed of several layers). The introduction of such a separation sheet also ensures protection of the mineral fiber (glass or basalt for example) in its implementation and in the possibly aggressive episodes of its use (for example with embankments comprising aggregates with protruding edges).

By implementing these technologies, the mineral fibers can be inserted into the machine while they have already been previously associated (association by twisting or by thermal process for example on the cord which has a thermoplastic portion ensuring welding and protection) . This assembly is optionally performed in line upstream with the job of producing the grid.

The fibers can also be directly associated on the machine in parallel introduction in the same comb, the same tube or the same passette of the machine.

Claims (10)

1. Geotextile woven lap or mesh, of which at least some of the threads, strands or cords (40, 45) parallel in at least one direction are composed on the one hand of mineral fibres having low elongation and an elongation at break value of 2 to 5%, and on the other hand of polymer fibres and/or natural origin fibres having a modulus of elongation under stress lower than that of the mineral fibres and an elongation at break value significantly higher than that of said mineral fibres, of 10 to 20%, characterized in that each simultaneously of said threads, strands or cords are composed on the one hand of said mineral fibres and on the other hand of said polymer fibres and/or natural origin fibres.
2. Geotextile woven lap or mesh according to claim 1, characterised in that the mineral fibres are made of a material chosen from the group comprising basalt, and various glass types with chosen properties such as, E-glass, S-glass, R-glass and AR-glass.
3. Geotextile woven lap or mesh according to one of claims 1 and 2, characterised in that the polymer fibres are made of a material chosen from the group comprising polyester, polypropylene and polyethylene.
4. Geotextile woven lap or mesh according to one of claims 1 to 3, characterised in that the natural origin fibres are made of a material chosen from the group comprising hemp, flax and coconut.
5. Geotextile woven lap or mesh according to one of claims 1 to 4, characterised in that it is made on a loom or Rachel type machine with or without inserting nonwoven (43, 63) or woven or even multi-layer lap.
6. Geotextile woven lap or mesh according to one of the preceding claims, characterised in that the mineral fibres are protected by a sheath or thermoplastic impregnation.
7. Geotextile woven lap or mesh according to one of claims 1 to 6, characterised in that the fibres, strands or cords are of a composite nature, notably by associating mineral fibres (41) and polymers (42), assembled beforehand by mechanical, thermal or chemical methods, keeping parallel strands or twisting them.
8. Geotextile woven lap or mesh according to one of claims 6 and 7, characterised in that before being made, the cords undergo a thermal treatment, on or off line, in order to protect the mineral fibres by impregnation of a thermoplastic material previously associated to the said cords.
9. Geotextile woven lap or mesh according to one of claims 6 and 7, characterised in that after being made, said lap or mesh undergoes a thermal treatment, on or off line, in order to protect the mineral fibres by impregnation of a thermoplastic material previously associated to the said lap or mesh.
10. Geotextile woven lap or mesh according to one of the preceding claims, characterised in that cellulose fibres and/or textured fibres or loops are inserted into its structure, in order to confer upon it a revegetation and/or anti-erosion function.

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