ES2372152T3 - FABRIC AND REINFORCEMENT MESH WITH MINERAL FIBERS INSERTED 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

Reinforcement fabric and mesh with mineral fibers inserted for civil engineering works

5 Technical scope

The present invention relates to a reinforcing fabric of the geosynthetic type or a mesh for civil engineering applications. This fabric or mesh contains at least one series of parallel reinforcing filaments, in which filaments based on mineral fibers or derived products are introduced. This fabric or mesh also contains, as com

10 complement, mineral fibers and / or fibers of plant origin in the ecological initiative.

Among the civil engineering applications capable of carrying out the object of the present invention, it is worth mentioning the reinforcement frames of the floor, slopes and embankments and reinforcing meshes of structural elements, for example tarred meshes, coated meshes, resins meshes and matrices, made mostly

15 in the context of public road works, railway constructions, retaining walls, bridge supports and roads, etc.

Prior art

20 In the field of civil engineering, reinforcement fabrics are commonly used to perform reinforcement functions

or assurance of a work, of its structural elements subjected to effort.

They can be associated with other materials (nonwovens, fabrics, spacer, resins, matrices) or they can be coated (with PVC, with impregnation of bitumen (tar) or other types) to ensure various functions, such as separates

25 tion between layers of soil, drainage, filtration, waterproofing or protection of all or part of the work. They can also be supportive fabrics, which emerge in the whole or in a part of their surface and that are dedicated to the function of vegetation and / or antierosion.

These fabrics are subject to the rules of the technique and the codes of the construction and must allow to ensure a long service life and the safety of the works, in which they intervene.

In particular, the quality of the framework fabrics must allow maximum mechanical properties to be preserved during the aggressive episodes suffered by the work, either during the course of its construction (fresh concrete, mechanical aggression ...), or during the subsequent course of the life of the work (infiltration, surrounding chemical environment,

35 geological sinking, exceptional overload ...). The cases of excessive temperatures, the specific chemical products, even the fire, of the emerging fabrics are emphasized above all. Polymer-based fabrics sometimes have insufficient properties for different cases.

The expected properties of these reinforcements are best explained by dividing them into two phases: 40

• in current use, under a load adapted to the behavior of the work in service, it is often essential to limit the deformations of the work to ensure its proper use. A material that has a good strength and a low level of deformation can ensure this function with advantage. Reinforcement fabrics based on ordinary polymers (polyester, polypropylene or polyethylene) do not ideally meet the necessary conditions

45 rias in terms of deformation, because they suffer an initial deformation that is too important when subjected to relatively low stresses.

• The mechanical capacities of the fabric used must also be sufficient to absorb more important loads on the scale of the work in cases of use to the limit (exceptional overload, geological deformation ...) and, thus, avoid breakage.

50 Although the dimensioning has been adjusted to these extreme situations, products made with classic polymers in fact have to be often oversized in the amount of material to achieve an acceptable deformation, sufficiently low during normal use. Low cost, common polymers exhibit excessive elongation when subjected to low stress.

55 At the level of breakage reinforcement, there is also a geosynthetic technique, described for example in document FR 2 767 344, which includes various materials with separate parallel fibers, for the same product, with advantage the PVA, which has an elongation at the breakage of 5% and at least one other material that has an elongation at breakage of at least equal to 12%. This technique ensures the reinforcement of the soil that runs the risk of sinking

60 (Fontis) thanks to a “parachute” effect, which results from this “multimodule”.

With a low rate of deformation, all subjects actively participate in the recovery of the work. When an overload or a disorder arises, the PVA material absorbs them to a deformation of 5%, after this value it will be the second material that will withstand the breakage and will indicate it with a significant deformation, but without breakage, for example, with the rolled (sunken area of the road through the passage of the wheels of the vehicles) of the road, which materializes the local subsidence, which requires repair.

Mineral fibers (glass, basalt ...) have not been used so far for these purposes for three reasons: 5

•

insufficient elongation at break to ensure the parachute function, which is described in the previously cited document;

•

complexity of the manufacture of meshes, which simultaneously include mineral fibers and polymers with problems of rupture of the mineral filaments by rubbing and shearing in the circuit provided for the polymers;

10 • fragility in the implementation in the work, in which it is necessary to apply a system that ensures the protection of glass fibers in soils that are mechanically aggressive for the fibers.

The manufacture of the fabric or the mesh can only be carried out, then, by means of an adapted technique and specific solutions for the implementation will have to be applied.

Description of the invention

The present invention relates to a reinforcing fabric or mesh, in which at least a part of the parallel reinforcing threads, filaments or twists in one direction are at least simultaneously composed of

20 mineral fibers or derived products (glass, basalt, fiberglass complex + thermoplastic impregnation material (supplied with the trademark Twintex®) ...) and polymer fibers and / or natural fibers.

In other words, the invention consists in associating inside the threads or twists, which form the fabric or the mesh and run in the same direction, mineral fibers of little elongation (high modulus of elasticity in tension) and

25 with a breaking elongation value between 2 and 5%, and polymer fibers and / or fibers of natural origin that have a modulus of elasticity in tension lower than that of mineral fibers and an elongation value of breakage significantly higher than said mineral fibers, which is between 10 and 20%.

The distribution of the filaments is thus heterogeneous. Thus, each thread or twist is composed of two associated materials according to one of the following procedures: filaments of mineral fibers and polymer fibers

or natural fibers, arranged in parallel, or twisted or even thermally associated, taking advantage of the thermoplastic properties of the fibers used.

This composition ensures an effective mechanical reinforcement, which complies with the rules of the technique, which provides the safety and long life required in the field of civil engineering.

Thanks to the mineral fibers, a high initial modulus is thus obtained, that is, a very low deformation, of the order of 2 to 3%, when relatively high stresses are absorbed, while with an equivalent breaking force, an organic polymer ordinary is capable of a deformation two to four times higher

40 (deformation of 5 to 7%) under the same conditions. This result is due to polymers that confer high strength together with a deformation level of at least 10% due to the principle of the multimodule that is practiced in this invention. This embodiment adapts perfectly to the behavior in the limit states normalized by the experts.

According to the invention, mineral fibers can be made of a material chosen from the group formed by basalt and different glass fibers of selected properties, such as glass E, glass S (thermally more resistant), glass R (high modulus) and AR glass (alkali resistant).

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

Also according to the invention, naturally occurring fibers can be made of a material chosen from the group consisting of hemp, flax and coconut.

55 To ensure a long service life and optimum quality together with a very low deformation in current use, the use of a mineral fiber, with the advantage of glass fiber, thanks to its high strength and low deformation allows recovering a part of the mechanical stresses that affect the work or the structural element, in order to limit its deformations and ensure its stability. This fiber has clear advantages in this aspect over the classic polymer fibers of the group of polyesters, polyethylene, polypropylene, especially with the possibility of

60 optimize the cost and quantity of materials.

It also allows dispensing with aramid fibers, which have a much higher cost, which makes them incompatible with many applications, due to the additional cost generated.

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

• Very high tensile strength with little deformation. The resistance of a standard pre glass

it shows a deformation at break of the order of 3%; 5 • much lower cost than low-stretch aramid fibers;

•

availability of less problematic matter;

•

Environmentally friendly design and manufacturing.

By comparison with materials, meshes and geosynthetic products that have mechanical properties equal

10 tes, such as products based on aramid fibers, carbon fibers, etc., the reinforcing fabric or mesh made according to the invention, which contains not only mineral fibers but also fibers of organic polymers and / or natural fibers (hemp , coconut, linen), provide a clear economic advantage derived from the cost of purchase and processing of this type of materials.

15 In certain cases of mechanically aggressive soils, it may be necessary to use a variant arranged in such a way as to protect the mineral fibers from external mechanical attacks, which could break them.

In these groups of filaments, there is the possibility of using a fiber of simple mineral matter, coated

20 ta, treated or protected, especially by a thermoplastic polymer, in the form of a lining or in the form of impregnation. Mineral fibers, glass, basalt and derived products, have advantageous behaviors, especially in terms of thermal resistance and chemical resistance. Treated, coated or protected fibers can be used to further improve the performance, for example of high temperature resistance glass, alkali resistant glass, basalt fibers, and especially the multifilament technique, in the one that

25 mix the glass and a thermoplastic, for example those sold under the trademark Twintex®. This latest technology ensures glass protection and durability. A heating system in radiant or other furnaces is integrated in the exit or in the center of the loom by feeding the warp and / or weft threads to the Raschel loom or loom, to perform the impregnation of the mineral reinforcing fibers With the thermoplastic product.

30 All these materials with a specific adaptation may be suitable for civil engineering applications, which claim a long service life, and for special situations, for example fire stability, treated soils, potentially shear granules mineral materials, the presence of high pH fresh concrete, etc.

According to a variant of the invention, cellulosic fibers and / or protruding fibers or loops are inserted into the fabric or mesh, in order to confer a vegetative and / or anti-erosion function.

Brief description of the figures

The manner of carrying out the invention and the advantages that it entails will be better highlighted in the following examples of embodiment, which are presented by way of illustration and not limitation, with the support of the attached figures.

Figure 1 is a representative curve of the deformation of a fabric, made of glass (left curve) and polyester (right curve), respectively, as a function of the applied load.

Figure 2 is a representative curve of the deformation of a fabric made according to the invention as a function of the applied load.

Figure 3 is a representative curve of the deformation of a fabric made of polyester alone, as a function of the applied load.

Figure 4 schematically illustrates a mesh of the invention, seen from above, with Figure 5 being a sectional view.

55 Embodiment of the invention

Figure 1 illustrates the tensile curve of two fabrics of two different materials (glass and PET), which selected in this way, may allow the invention to be carried out with an economically advantageous behavior in

60 terms of amount of glass with respect to the amount of polyester. It is shown in this figure 1 that for an equivalent effort, the deformation of the fabric made of glass is significantly lower than that of the fabric made of polyester. For example, for a load or an effort of 80 KN, the deformation of the glass is of the order of 2%, while that of the polyester is already 6%.

Figure 2 illustrates the behavior of a fabric manufactured according to the invention using simultaneously two types of fibers, namely polyester and glass. In the initial phase of undergoing an effort, that is, in normal use, glass will be primarily the material that will ensure resistance with a very low deformation. If the efforts increase, the glass breakage will occur due precisely to its low deformation, said breakage will occur.

5 will materialize at the first point of inflection of the curve, but then it goes into action in polyester, materialized at the second point of inflection of the curve.

The curve represented in Figure 3 indicates that it would be possible to obtain an initial stiffness with polyester alone, but with a more important polyester weight, whose resistance to breakage would be much higher than 450 KN (upper curve),

10 when a total resistance of 145 KN (curve below) was necessary in this example.

It is understood that the cost of the solution according to the invention is very interesting because it avoids the use of a quantity of material approx. three times higher. This excess is replaced by a very low cost mineral fiber.

Figure 4 illustrates the embodiment and arrangement of twists according to the invention. In this case, each twist (40), according to at least one of the directions, results from associating two materials (41) (glass or basalt fibers) and (42) (high tenacity polyester fibers or natural fibers) . In the example described, these twists are juxtaposed on a nonwoven or woven fabric (43) or composed of several layers and / or on weft threads (45), made for example with polyester (in Figure 4) or also with twists of the same structure (figure 5). They already know each other

20 either the techniques of association of twists or fibers in a fabric and / or on the weft threads with a knitting machine or with a Raschel weft loom, so it is not necessary to describe them here in more detail. The twist ligature threads (40) with the fabric (43) and the weft threads (45) have been simply realized with reference (44).

Figure 5 is a schematic representation of the section of Figure 4, which makes it possible to better distinguish this structure.

The mineral (41) and polymer or natural fibers (42), respectively, are associated within the aforementioned twists (40), for example by twisting or twisting or parallel insertion. Also, these crooked ones are

30 optionally lined with a protective thermoplastic, for example with heat input, either before assembly (mineral fibers lined with thermoplastic material, for example with polyester), or after assembly (OWENS CORNING technology for twisting type Twintex®).

According to the invention, the multicomponent fabric or mesh can be manufactured in looms commonly used for

35 the manufacture of fabrics (for example DORMIER or SULZER looms), or by warp and Raschel technology (loom of the Karl Mayer or Liba type, for example), with or without weft insertion. These technologies allow to work the mineral fibers, for example of glass or basalt, without altering the fiber, especially in the mechanical plane, manufacturing complex structures and meshes that include many more materials.

40 The looms can work according to the classic textile ligaments or according to the gauze step type ligaments, which allows a minor impregnation of the reinforcing fibers using fine ligature threads.

Raschel technology also allows the realization of multifunctional products by insertion of separating fabrics (non-woven or woven or composed of several layers). The introduction of a separation fabric of this type ase

45 also protects the protection of mineral fiber (glass or basalt, for example) during its implementation and during the eventual aggressive episodes of its use (for example, on embankments containing granules with protruding edges).

When these technologies are implemented, mineral fibers can be inserted into the machine after

50 having previously been associated (association by twisting or by a thermal procedure, for example, applied to the twisting, which already has a thermoplastic part that ensures welding and protection). This assembly is carried out in line beforehand, with the loom, in which the mesh is made.

The fibers can also be directly associated in the machine by parallel introduction in the same comb, the same tube or the same machine guide.

Claims (8)

1. Woven fabric or geotextile mesh, in which at least a part of the strands, filaments or twists (40, 45) parallel in at least one direction is formed on the one hand by mineral fibers of reduced elongation and having 5 an elongation value at break between 2 and 5% and on the other hand by polymer fibers and / or fibers of natural origin that have a modulus of elasticity in tension lower than that of mineral fibers and an elongation value at breakage significantly higher than said mineral fibers and between 10 and 20%, characterized in that each of said threads, filaments or twists is formed on one side of said mineral fibers and on the other hand by polymer fibers and / or of fibers of natural origin. 2. Woven fabric or geotextile mesh according to claim 1, characterized in that the mineral fibers are manufactured with a material chosen from the group formed by the basalt and different types of glass of selected properties, for example glass E, glass S, the R glass and AR glass. 3. Woven fabric or geotextile mesh according to one of claims 1 and 2, characterized in that the polymer fibers are made of a material chosen from the group consisting of polyester, polypropylene and polyethylene. 4. Woven fabric or geotextile mesh according to one of claims 1 to 3, characterized in that the source fibers Natural are made with a material chosen from the group formed by hemp, flax and coconut. twenty 5. Woven fabric or geotextile mesh according to one of claims 1 to 4, characterized in that it is manufactured in a textile machine or in a machine of the Raschel type, with or without insertion of non-woven fabric (43, 63) or woven or even multilayer

A woven fabric or geotextile mesh according to one of the preceding claims, characterized in that the mineral fibers have a protection formed by a lining or by a thermoplastic impregnation.

7. Woven fabric or geotextile mesh according to one of claims 1 to 6, characterized in that the fibers, filaments

or twisted are of a composite nature and, above all, they are associated with mineral fibers (41) and polymers (42), 30 previously assembled by a mechanical, thermal or chemical process, and keep the filaments parallel

or they apply a twist. 8. Woven fabric or geotextile mesh according to one of claims 6 and 7, characterized in that before manufacturing The twists are subjected to a heat treatment, in line or not, in order to ensure the protection of the mineral fibers by impregnation with a thermoplastic material previously associated with said twists. 9. Woven fabric or geotextile mesh according to one of claims 6 and 7, characterized in that after manufacturing it is subjected to a heat treatment, in line or not, in order to ensure the protection of mineral fibers by impregnation with a material thermoplastic previously associated with said fabric or mesh. 10. Woven fabric or geotextile mesh according to one of the preceding claims, characterized in that cellulosic fibers and / or embossed fibers or loops are inserted into its structure, in order to confer a vegetative and / or anti-erosion function on it.