EP2439342B1 - Reinforcement mesh - Google Patents

Description

The present invention relates to reinforcing mats comprising at least one carrier layer and at least one cover layer, wherein the carrier layer and / or the cover layer are hydrophobic equipped, processes for their preparation and the use of reinforcing mats according to the invention for reinforcing tasks in hydraulic engineering and coastal protection.

Geosynthetics, such as sealing mats and reinforcing mats are used for filter and reinforcement tasks in hydraulic engineering and coastal protection. In addition, buildings are increasingly being designed today, in which the geosynthetic takes over the function of packaging for locally occurring soil materials. For example, in order to stabilize natural dunes in sandy and erosion-prone coastal areas, invisible, flexible helicopters from geosynthetics are increasingly being used, which act as the second line of defense for the dune in the event of a storm surge.

Geosynthetics are also used in the filling and sealing of docks.

In general, geosynthetics, ie water-permeable nonwovens or fabric, placed on soft soil layers, for example, to prevent the partial sinking of the embankment in the soft ground or embankment fractures or very different subsidence.

Soft soils are, for example, organogenic soils, especially silt. In these organogenic soils, gas-forming processes that are caused by bacteria take place.

It has been observed that during the incorporation of conventional geosynthetics between localized silt and sand used for surface elevation, surface deformation occurred. It was found that the deformations were caused by the formation of gas bubbles under the geosynthetic. The deformations lead to an instability of a structure, such as a harbor basin, and thus do not ensure the adequate sole securing of docks.

A reinforcing mat according to the preamble of claim 1 is made EP 0 278 419 A2 known.

Against this background, the present invention seeks to provide a reinforcing mat, in which the aforementioned problems do not occur and the rest of the above requirements, in particular for installation under water, is sufficient. Furthermore, a method for cost-effective and practical manufacture of such an improved reinforcing mat is to be provided.

These objects are achieved according to the invention by the features of claim 1 and the features of claim 11. Advantageous embodiments of the invention will become apparent from the dependent claims and the description below.

The reinforcing mat according to the invention comprises at least one carrier layer and at least one cover layer. The cover layer consists of nonwoven fabric and the carrier layer of nonwoven fabric or a woven or knitted fabric. Carrier and cover layer are connected to each other, wherein according to the invention, at least the support layer or the cover layer are hydrophobic equipped.

The surface tension is used to characterize the hydrophobicity of the carrier layer or cover layer. This can be determined, for example, by measuring the static contact angle of water on a smooth surface of the carrier or cover layer. Hydrophobic carrier layers or cover layers are characterized by static contact angles for water of at least 90 °. The surface tension can also be determined by the "hanging drop" method (Pendent Drop: see S. Wu "Polymer Interface and Adhesion", Marcel Dekker Inc., New York 1982, pp. 266-268 ). The values given for the surface tension of the carrier or cover layer here and below refer to the values determined by the hanging drop method. Hydrophobic supports or cover layers in the sense of the invention have a surface tension in the range from 20 mN / m to 50 mN / m.

The reinforcing mat according to the invention is eminently suitable for passing gas under the mat, even when the reinforcing mat is installed under water or in damp or soaked ground, so that the gas bubble accumulation known from the prior art results in deformations and instability of the structure can be avoided.

Preferably, both the carrier layer and the cover layer are hydrophobic.

Expediently, an intermediate layer is arranged between the carrier layer and the cover layer, which, since the carrier layer and cover layer are connected to one another, is fixed by the adjacent layers or their connection components. Such an intermediate layer can advantageously consist of sand, typically quartz sand, but also of other suitable materials. A particularly durable and shear-transmitting composite between the carrier layer and the cover layer, in particular under inclusion of the Intermediate layer, is formed when the carrier layer and the cover layer are connected to each other by needling or sewing, as in the composite of such layers in principle belongs to the prior art.

Advantageously, not only one of the two layers (carrier or cover layer) but both the carrier layer and the cover layer are hydrophobic equipped. It is particularly advantageous if all layers are hydrophobic. The hydrophobic finish of at least one preferred all layers of the reinforcement mat ensures a certain gas permeability of the mat, even when installed under water or in moist soils. The hydrophobic finish is accomplished by means of a hydrophobing agent, typically by applying a finish.

Preferably, both the carrier layer and the cover layer of nonwoven fabric.

In principle, all nonwovens known from the prior art are suitable for producing the reinforcing mat according to the invention. Preferably, the nonwoven fabric used is a mechanically consolidated staple fiber nonwoven. It is designed so that the crimped fibers form a fabric with countless labyrinthine passages. Here, the soil structure is ideally replicated. The structure of the nonwovens can be adjusted coarser or finer, depending on the nature of the soil, so that optimal adaptation to the pending soil type is ensured. The mechanical consolidation guarantees a high coefficient of friction between the pending floor and the nonwoven fabric as well as the cover. The staple fiber webs used can be mechanically consolidated by needlepunching, by means of sewing technique or by swirling.

The nonwovens used in the invention are rot-proof, d. H. Resistant to all substances occurring in the body of water and in the soil and thus demonstrably guarantee an extremely long service life. Their extremely high tear strength causes a substantial insensitivity to mechanical stresses. They are highly UV-stable and have a high specific gravity. Preferably, the nonwovens consist of a plastic selected from the group consisting of polyamide, polyolefin, polyacrylic and polyester. Nonwoven fabrics of polyolefin, such as, for example, nonwovens of polyethylene and / or polypropylene, are particularly preferred.

In principle, the solidification of the nonwoven fabrics can be carried out in any known manner. Thus, it is possible, for example, to solidify the nonwoven by a binder with which the nonwoven fabric is impregnated, and then cured. Also, the binder may be a melt binder, which is incorporated, for example, in powder form or in the form of binder threads in the nonwoven and solidifies the nonwoven under heat to the nonwoven fabric. Likewise, the solidification of the nonwoven fabric to the nonwoven fabric can also be done by calendering, wherein partly occurs a mechanical entanglement of the filaments, partly an autogenous weld at the intersection points.

The basis weight of the textile reinforcing mat according to the invention of course depends on the intended use. In this case, a high basis weight or a high specific gravity of > 1.2 g / cm ^{3 is} advantageous in the underwater installation of the reinforcing mat. Preferably, the basis weight of the reinforcing mat is in the range between 2.300 g / m ² and 12,200 g / m ² , more preferably in the range between 4,500 g / m ² and 7,200 g / m ² . The nonwoven fabric is permeable to water. The nonwoven fabric preferably has a water permeability in the range between 20 l / s × m ² and 120 l / s × m ² , more preferably in the range between 40 l / s × m ² and 100 l / s × m ² (according to DIN EN ISO 11058).

If the carrier layer consists of a woven or knitted fabric, this is a synthetic fiber fabric. The fabric or knitted fabric is also permeable to water. Suitable woven or knitted fabrics consist for example of multifilament yarns and of high-density polyethylene (PEHD), polypropylene (PP) or polyester (PES). The carrier layer and the cover layer are connected to one another. Preferably, the carrier layer and the cover layer can be joined together by needling. In a further embodiment, it is possible to sew cover layer and carrier layer together.

Preferably, both the carrier layer and the cover layer are formed antistatic. The antistatic formation of the nonwoven fabrics can be carried out, for example, with metallic fibers or by needling with antistatic textile fibers, for example carbon fibers or materials which are comparable in effect.

Preferably, the basis weight of the carrier layer is in the range of 100 g / m ² to 1,000 g / m ² mm, particularly preferably in the range of 200 g / m ² to 600 g / m ² mm. Depending on the reinforcement requirement from the project, the grammage may vary. The basis weight of the intermediate layer is preferably in the range from 2,000 g / m ² to 10,000 g / m ² , more preferably in the range from 4,000 g / m ² to 6,000 g / m ² . The surface weight of the cover layer is preferably in the range from 200 g / m ² to 1,200 g / m ² , particularly preferably in the range from 300 g / m ² to 600 g / m ² .

The intermediate layer varies in its basis weight due to the requirements of the construction project, with regard to the laying and possibly occurring flow velocities during underwater installation and with respect to their mass and drainage capacity with regard to the grain size and type of interlayer material.

The reinforcement mat is permeable to gas. In particular, the reinforcing mat is permeable to gases such as nitrogen and methane. The hydrophobic finish of the carrier layer or cover layer is achieved by using a hydrophobing agent. The hydrophobizing agent used for the hydrophobizing coating covers the nonwoven fabric or woven and knitted fabric with a very thin layer of hydrophobic groups, such as, for example, long-chain alkyl radicals or siloxane groups. Suitable hydrophobizing agents are selected from the group consisting of paraffins, waxes, metal soaps with additions of aluminum or zirconium salts, quaternary ammonium compounds with long-chain alkyl radicals, urea derivatives, fatty acid-modified melamine resins, chromium complex salts, silicones, organotin compounds, glutaric dialdehyde and perfluorinated compounds. The hydrophobized carrier or cover layer is characterized by the fact that drops of water roll off on it without moistening.

The hydrophobization is preferably carried out by the use of silicones, such as, for example, polysiloxanes. Preferred polysiloxanes are, for example, polydialkyl or alkylaryl siloxanes in which the alkyl groups have 1-5 carbon atoms and are fully or partially fluorinated. Polysiloxanes which are likewise preferred are polydimethylsiloxanes which may optionally be derivatized and are then amino-functional or quaternized or have Si-OH, Si-H and / or Si-Cl bonds. Likewise preferred polysiloxanes are the polyalkylene oxide-modified polysiloxanes, ie polysiloxanes which comprise, for example, polyethylene glycols, and the polyalkylene oxide-modified dimethylpolysiloxanes.

The polysiloxanes are in the form of an aqueous emulsion which, in addition to water, may contain emulsifiers and surface-active agents, and are also referred to as hydrophobic softening agents. Appropriate Products can be obtained under the trade names Evo Soft® SME and Synthesin® SE 128 FILL from DyStar, Leverkusen.

The hydrophobic softening agent preferably has a content of hydrophobizing agents in the range from 10 to 40% by weight, particularly preferably in the range from 10 to 30% by weight. The hydrophobic coating preferably has a content of polysiloxanes in the range from 10 to 40% by weight, particularly preferably in the range from 10 to 30% by weight.

Another object of the present invention is a process for producing a reinforcing mat, comprising at least one carrier layer and at least one cover layer, wherein the cover layer of nonwoven fabric and the carrier layer of nonwoven fabric or a woven or knitted fabric and the layers are interconnected, wherein at least the Carrier or the top layer are hydrophobic equipped.

For hydrophobization of a nonwoven fabric, which may form the carrier or cover layer of the reinforcing mat, it is necessary that this nonwoven fabric itself is hydrophilic. In principle, various processes can be used for the hydrophilic finishing of nonwovens. On the one hand, it is possible that the fibers of the nonwoven fabric are hydrophilized in fiber production by adding at least one hydrophilizing additive. For example, in the production of the nonwoven fabric, an additive may be added to the melt, which migrates to the surface of the nonwoven fiber at a later time and then, when wetted with water, reduces its surface tension. Under the trade name "ARGUTEC HYL 09 PP" from Argus, a masterbatch with a mixed silicate and erucic acid amide based on polyethylene is available, which can be used as a hydrophilicizing agent. It is also possible that the fibers of the nonwoven fabric itself during or after production by external application with at least hydrophilizing a hydrophilicizing agent. For example, an external application of a hydrophilic finish or soap solution is possible. The hydrophilic finishing agent is a liquid that contains substances that remain on the fiber surface after wetting and subsequent drying. These substances reduce the surface tension when re-wetted with water in the case of using a hydrophilic lubricant. For example, surfactants can be used in this sense. The liquid hydrophilizing agent may be applied by soaking, spraying, nebulizing or the like. Ultimately, the hydrophilization of the fibers of the nonwoven layer or else the nonwoven layer as a whole is possible by any suitable chemical and / or physical treatment. Also, pretreatments of the nonwoven fabric or the fibers are possible, for example, by a corona or plasma pretreatment.

For the preparation of the reinforcing mat, the treatment of a hydrophilic carrier layer and / or a hydrophilic top layer with a hydrophobing agent should be carried out before joining these layers to a reinforcing mat.

To prepare a reinforcing mat, the usual methods described in the prior art can be used. By way of example, the methods are out EP 0 278 419 A2 , Pages 5 - 7, called. Prior to bonding the backing and topcoat, the hydrophobizing agent is applied in a bath through which the geosynthetic material passes. Alternatively, the application of the hydrophobing agent by spraying a hydrophobic coating on a composite of support layer and cover layer can take place.

It is likewise possible to apply the hydrophobizing agent to the geosynthetic material before it is bonded to one another as a carrier layer or cover layer. Here, in the spray flushing a aqueous dispersion or emulsion of the hydrophobic coating is sprayed onto a continuously running geosynthetics via suitable nozzle systems. It is likewise possible to guide the geosynthetic material through an appropriate aqueous emulsion or dispersion of the hydrophobic finish and then to squeeze, to spin off or strip off the entrained finish from the sewing thread.

The reinforcing mat according to the invention can be used as geosynthetics in a variety of applications, for example in dike construction as a flat sealing, filtering and drainage layer, for erosion protection or for reinforcement. Another object of the present invention is therefore the use of a reinforcing mat according to the invention for sole and slope protection, in particular for securing the bottom of docks, in coastal protection, in the revetment, in the flexible sole protection, the pillar protection and as a foot template to longitudinal and transverse works.

Claims (14)

1. A reinforcement mat, comprising at least one carrier layer and at least one cover layer, wherein the cover layer consists of a non-woven, and the carrier layer of a non-woven or woven fabric or knitted fabric, and the layers are connected to one another, characterised in that at least the carrier layer or the cover layer are designed in an hydrophobic manner.
2. A reinforcement mat according to claim 1, characterised in that the carrier layer and the cover layer consist of a non-woven.
3. A reinforcement mat according to one of the preceding claims, characterised in that an intermediate layer is arranged between the carrier layer and the cover layer.
4. A reinforcement mat according to one of the preceding claims, characterised in that the intermediate layer consists of sand.
5. A reinforcement mat according to one of the preceding claims, characterised in that the carrier layer and the cover layer are connected to one another by way of needling.
6. A reinforcement mat according to one of the preceding claims, characterised in that the carrier layer and the cover layer, preferably all layers are designed in a hydrophobic manner.
7. A reinforcement mat according to one of the preceding claims, characterised in that the carrier layer and/or cover layer are designed in a hydrophobic manner with a hydrophobing means.
8. A reinforcement mat according to one of the preceding claims, characterised in that the non-woven consists of mechanically strengthened staple fibre non-wovens.
9. A reinforcement mat according to one of the preceding claims, characterised in that the non-woven consist of non-rotting plastic fibres, preferably polyolefin fibres.
10. A reinforcement mat according to one of the preceding claims, characterised in that the carrier layer consists of a non-rotting plastic woven fabric, preferably a tape fabric.
11. A method for manufacturing a reinforcement mat according to one of the preceding claims, comprising at least one step, in which a mat comprising at least one hydrophilic carrier layer and a hydrophilic cover layer is treated with a hydrophobing agent.
12. A method according to claim 11, characterised in that the hydrophobing agent is deposited in a bath.
13. A method according to claim 11, characterised in that the hyrophobing agent is deposited by spraying on.
14. The use of a reinforcement mat according to one of the preceding claims for bed protection and slope protection, in particular for bed protection of harbour basins, coastal protection, embankment protection, in flexible bed protection, scour protection and as revetments for longitudinal and transverse hydraulic structures.