Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
  • E02D31/002—Ground foundation measures for protecting the soil or subsoil water, e.g. preventing or counteracting oil pollution
  • E02D31/004—Sealing liners

Definitions

• the present invention relates to a water and / or oil impermeable sealing mat which essentially consists of a layer of swellable clay provided with cover layers.
• Such a sealing mat is known from European patent 0 059 625, in which a flexible carrier layer carries a bentonite layer, on which in turn a cover layer can be located. All three layers, i.e. the backing layer, which can be a nonwoven fabric, the bentonite layer and the cover layer, which can be an unspecified mat, are connected to one another by means of an adhesive.
• the backing layer and the top layer are only connected to one another via the bentonite layer, so that when used, due to the adhesive bond which is released when the bentonite layer becomes moist, there is no firm connection between the backing layer and the top layer.
• This sealing mat essentially consists of a backing layer, a layer of swellable clay and a top layer, the backing and / or top layer consisting of a nonwoven fabric and the layer which may not consist of a nonwoven fabric consisting of a woven fabric, knitted fabric or a plastic film, whereby all three layers are needled together.
• the carrier layer and the top layer remain by the needling also during and after the swelling of the swellable clay firmly connected, the bentonite particles being enclosed by the fibers which extend from the cover layer through the bentonite layer to the carrier layer and vice versa, as in a cage.
• this own German patent specification 37 04 503 already states that a reduction in the water permeability of these sealing mats can be achieved by first applying a floury bentonite to the support layer and, if necessary, shaking it and only then applying the granular bentonite granules. Instead of shaking the floury bentonite into the carrier layer, one can also proceed by first impregnating the carrier layer with an aqueous bentonite suspension or rolling on an aqueous bentonite paste and only then, if necessary after prior drying, applying the granular bentonite granules. If desired, the top layer can also be treated in the same way as the carrier layer before it is applied.
• the object of the present invention is therefore to provide a sealing mat which not only reduces the work in connection with the very complex and very carefully carried out joining technology, but also simplifies it in principle, while still meeting the requirements with regard to the water permeability coefficients in the overlap area, which should be of the same order as the water permeability coefficients of the sealing mat itself, and the requirements regarding the transmission of shear force are met.
• porous carrier material with the swellable clay embedded therein is provided on both sides with cover layers, at least one of which consists of a water-soluble film.
• the backing material used according to the invention acts like a scaffold in the sealing mats according to the invention, which gives the moist bentonite layer which is formed in use excellent stability and, on the one hand, ensures that the moist bentonite layer does not become a sliding plane and, on the other hand, the desired transmission of thrust is ensured. Since, when laying the sealing mats according to the invention, care must also be taken that the overlapping sealing mats always have to be laid such that two water-soluble cover layers always lie one on top of the other, this further ensures that the bentonite layers of the overlapping sealing mats in the moist state so get intimate contact that the water permeability coefficients in the overlap area are in the same order of magnitude as the water permeability coefficients of the sealing mat itself.
• the fact that the bentonite layers come to lie practically directly on top of one another means that none of the complex and carefully carried out joining techniques need be used, which means an enormous simplification of the laying work with regard to the sealing mats on the construction site.
• the sealing mats according to the invention can be needled in situ in the overlap area, so that a non-positive connection is obtained in the overlap area, which ensures that there is no displacement of the nonwoven layers in the overlap area is possible.
• the "in situ needling" is described in the own older patent application P 41 22 991.6-26.
• the present invention thus relates to a water and / or oil impermeable sealing mat, which essentially consists of a porous carrier material, in the pores of which swellable clay is embedded and which is characterized in that the porous carrier material with the swellable clay incorporated therein is provided on both sides with cover layers, at least one of which consists of a water-soluble film.
• the swellable clay embedded in the pores is preferably a bentonite.
• Bentonites are clays with a noticeable to high content of smectite (montmorillonite), which determines the properties (high swellability, good water binding capacity, high plasticity).
• the alkaline earth ions of the bentonites are replaced by alkali ions, preferably sodium ions.
• alkali ions preferably sodium ions.
• Sodium bentonite with its greatly increased plasticity, viscosity, thixotropy and water absorption is therefore preferred as the "highly swellable" active bentonite.
• the naturally occurring sodium bentonites are particularly preferred, in particular those that come from the mining area in Wyoming, USA.
• the porous carrier material preferably consists of a nonwoven fabric or an open-cell foam plastic.
• nonwovens and the foamed plastics which are at least so elastic that they can be wound on a roll, large-pored are preferred.
• the preferred foamed plastics include open-pored flexible polyurethane foams.
• the nonwovens used preferably consist of quality plastic fibers, in particular of polyethylene, polypropylene, polyester, polyacrylic and / or polyamide fibers.
• quality plastic fibers in particular of polyethylene, polypropylene, polyester, polyacrylic and / or polyamide fibers.
• Particularly preferred in the field of landfill technology are nonwovens made of high density polyethylene (HDPE) or polypropylene, which are rot-proof (resistant) to all substances found in water and in the ground and are therefore demonstrably extremely high Ensure durability.
• HDPE high density polyethylene
• polypropylene which are rot-proof (resistant) to all substances found in water and in the ground and are therefore demonstrably extremely high Ensure durability.
• Their extremely high tensile strength means that they are largely insensitive to mechanical stress.
• the nonwovens used are preferably spunbond nonwovens mechanically consolidated by needling. They are constructed in such a way that the crimped fibers form a flat structure with innumerable labyrinthine passages.
• the structure of the nonwovens can be adjusted coarser or finer depending on the area of application, so that an optimal adaptation to the requirements is guaranteed.
• the mechanical strengthening guarantees a framework structure that is essential for the purposes of the invention.
• the nonwovens mechanically consolidated by needling it is also possible to use those nonwovens which have been mechanically consolidated by means of sewing technology or by swirling, or those nonwovens which have been chemically consolidated.
• the porous carrier material is a two-layer composite nonwoven made of a coarse-pore nonwoven and a fine-pored nonwoven or a fine-mesh woven or knitted fabric or a finely perforated film, the fine-pored nonwoven or the woven or knitted fabric or the film forming the top layer .
• the two-layer composite nonwovens which can be used according to the invention include, for example, those which have been marketed by Naue-Fasertechnik for years under the trade name "TERRAFIX” as tried and tested hydraulic engineering mats.
• the production width is usually 4.80 m and the length 100 m.
• One nonwoven layer consists of a filter layer (fine-pore nonwoven) made of polyester and a drain layer (coarse-pore nonwoven) made of polypropylene fibers. The fibers are by needling solidified mechanically.
• This two-layer composite fleece, which serves as a carrier layer has a layer thickness of greater than 6.0 mm. The characteristic values of such a two-layer composite fleece are shown in Table 1 below.
• Another two-layer composite fleece suitable for the purposes of the present invention can be constructed such that a coarse-pored Nonwoven fabric is needled with a fabric, preferably a fine-mesh fabric, or a knitted fabric, preferably a fine knitted fabric, or a finely perforated film.
• a three-layer composite fleece can also be advantageous, which consists of two coarse-pore nonwovens needled together, with a fine-mesh fabric or knitted fabric or a finely perforated film between the two nonwoven layers, which is also needled.
• a fine-mesh fabric or knitted fabric or a finely perforated film between the two nonwoven layers, which is also needled.
• only the one large-pore nonwoven layer is filled with bentonite and then sealed with the water-soluble film.
• the other, non-filled, coarse-pored nonwoven layer serves to compensate for unevenness in the ground and to ensure that the installed sealing mat is non-slip.
• the laying is carried out in such a way that the top layer consisting of water-soluble film comes to lie alternately upwards and downwards, so that the top layers of water-soluble film always lie directly in the overlap region Are in contact with each other.
• the water-soluble cover layer or the fine-pored nonwoven, the woven fabric, the knitted fabric or the film is colored.
• these "multi-layer composite nonwovens" sealing mats are laid in such a way that first two webs of the sealing mats are laid parallel to one another at a distance with the water-soluble top layer and then a third web of the sealing mat with the water-soluble top layer facing down on the free floor strip, the distance between the two sealing membranes laid first so that the desired overlap width is obtained on both sides.
• sealing mats according to the invention are used which carry the water-soluble film as a covering layer on both sides, the laying can be carried out in the usual way, since with these sealing mats two covering layers of water-soluble film inevitably come to lie on top of one another.
• Purely inorganic films include those based on water glass.
• Aqueous solutions of alkali silicate, preferably of sodium silicate are suitable as water glasses.
• Such water glass solutions are commercially available and form the desired film on drying, it having proven particularly advantageous if bentonite, preferably sodium bentonite, is introduced into such an aqueous water glass solution.
• bentonite preferably sodium bentonite
• the mixing of the water glass solution with the bentonite is most conveniently carried out in such a way that an aqueous bentonite dispersion is prepared beforehand, and this is then mixed with the aqueous water glass solution.
• the amount of bentonite to be introduced depends entirely on the viscosity with which you want to apply the silicate solution. In addition to low-viscosity mixtures, those which are pasty and which are knife-coated or rolled onto the surfaces to be sealed are also suitable.
• aqueous starch preferably a sodium bentonite
• bentonite preferably a sodium bentonite
• aqueous starch glues include in particular those based on potato and corn starches. If necessary, these starch glues are used in combination with casein solutions.
• the water-soluble dextrin glues are used.
• the dextrins are thermal breakdown products of the starches.
• Casein glues include those that were made in particular from milk protein.
• so-called collagens from animal hides and bones can be used for glue jellies and glutin glues instead of casein glues.
• methyl cellulose which is used in aqueous solutions e.g. B. is used as wallpaper paste.
• cellulose esters special mention should be made of cellulose acetate, which is soluble in water with a degree of esterification of 0.6 to 0.9 and a content of bound acetic acid of 18 to 26%.
• water-soluble film formers preferred according to the invention include those based on polyvinyl alcohol.
• polyvinyl alcohols of course only those are preferred which form aqueous solutions and which are used, for example, for simple paper gluing.
• aqueous polyvinyl alcohol solutions are also preferably used in a mixture with bentonite.
• the aqueous coating compositions forming the cover layers can be sprayed on, knife-coated, rolled on or applied by means of other known techniques. Since the cover layers should dry relatively quickly, it is advisable to blow them off with hot air or to move them past appropriate heating elements. B. radiant heaters allow a quick drying process.
• both sides of the sealing mat are sealed with the water-soluble films.
• the bentonite powder is sprinkled and shaken on a coarse-pored nonwoven fabric that is transported lying on a lower conveyor belt and covered with an upper conveyor belt. Both conveyor belts are then guided vertically upwards with the filled sealing membrane in between, both conveyor belts being deflected at the same height to the return.
• the water-soluble film is then applied from both sides at the same time and then dried.
• the resulting sealing sheet is then wound on a roll for use.

Applications Claiming Priority (2)

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Citations (4)

• 1992
  • 1992-02-11 DE DE4203861A patent/DE4203861A1/de not_active Withdrawn
  • 1992-12-23 SK SK3853-92A patent/SK385392A3/sk unknown
  • 1992-12-23 CZ CS923853A patent/CZ385392A3/cs unknown
• 1993
  • 1993-02-08 AT AT93101929T patent/ATE122120T1/de not_active IP Right Cessation
  • 1993-02-08 DE DE59300170T patent/DE59300170D1/de not_active Expired - Fee Related
  • 1993-02-08 EP EP93101929A patent/EP0555800B1/fr not_active Expired - Lifetime
  • 1993-02-10 MX MX9300720A patent/MX9300720A/es not_active Application Discontinuation
  • 1993-02-11 CA CA002089331A patent/CA2089331A1/fr not_active Abandoned

Patent Citations (4)

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