Geomaterial web with biological degradation properties

Abstract

A geomaterial web includes a first organic structural material and a second structural material that is different from the first structural material, which is bonded together with the first structural material to form a sheet-like composite material web extending in two mutually perpendicular directions. The first structural material and the second structural material are organic materials, where the first structural material has a first biodegradability and the second structural material has a second biodegradability that is different from the first biodegradability. The second biodegradability may be less than the first biodegradability.

Claims

1. A geomaterial web, comprising: a first organic structural material and a second structural material that is different from the first structural material and that is bonded to the first structural material to form a sheet-like composite material web extending in two mutually perpendicular directions; wherein the first structural material and the second structural material are organic, fibrous non-woven materials; wherein the first structural material is a plastic material, and wherein: the first and the second structural material have a first and a second biodegradability, respectively, to the extent that: in a composting test with the following parameters: samples with a length of 10 cm, a width of 10 cm and an original material thickness, 50 C.+/5 C., thermophilic conditions according to ISO 16929:2018-04 (modified only according to the temperature range set forth above), sieving of solids after six months in a sieve with 2 mm mesh (mesh 8.75), and when sieving, less than 80 wt. % dry matter of the an initial dry matter of the starting material remains in the sieve; or in a marine incubation test with the following parameters: samples with a length of 2 cm, a width of 2 cm and an original material thickness, 30 C.+/2 C., aerobic conditions in seawater with a salinity of 3.5 wt. %+/1 wt. %, sieving of solids after twelve weeks in a sieve with 2 mm mesh (mesh 8.75), and when sieving after twelve weeks, less than 80 wt. % dry matter of a dry matter of the starting material remains in the sieve; and the second structural material has a second biodegradability which is different from the first biodegradability.

2. The geomaterial web according to claim 1, wherein the second biodegradability is lower than the first biodegradability.

3. The geomaterial web according to claim 1, wherein the first structural material is arranged in the geomaterial web in such a way that, after partial or complete biological degradation of the first structural material, openings are formed in the geomaterial web passing through the geomaterial web.

4. The geomaterial web according to claim 3, wherein the first structural material partially or completely penetrates the second structural material; or wherein the first structural material and the second structural material core bonded together as a layered composite, the second structural material has a plurality of second perforation openings, and the first structural material has no perforation openings, or has a plurality of first perforation openings that are smaller than the second perforation openings.

5. A method of using a geomaterial web according to claim 1, wherein the geomaterial web is incorporated into a soil layer for the purpose of soil stabilization.

6. The geomaterial web of claim 1, wherein; the geomaterial web has a polymer group comprising a molecule provided with an isotopic label comprising a .sup.13C or .sup.18O-isotopic label; or the geomaterial web comprises said first and second structural materials that are biodegradable.

7. The geomaterial web of claim 1, wherein the geomaterial web is formed by a single-layer or multilayer nonwoven filter fabric made of at least said first and second structural materials bonded together to form a nonwoven fabric, wherein: the first and second structural materials are fibrous non-woven materials and the first structural material is a plastic material, the first structural material exhibits biodegradability under a predetermined intensity of an influencing parameter at an installation site to the extent that a weight percentage of more than 50% of the structural material is converted to carbon dioxide within six months in an aqueous medium, wherein the predetermined intensity of the influencing parameter is selected from: an intensity of a radiation effect of an electromagnetic radiation; a height of a temperature; a concentration of a substance reacting chemically or biochemically with the geomaterial web; a concentration of bacteria; or a concentration of fungi; and the second structural material is bonded to the first structural material to form the nonwoven filter fabric, the second structural material having biodegradability under the same predetermined intensity of influencing parameter at the same installation site to the extent that: in a composting test with the following parameters: samples with a length of 10 cm, a width of 10 cm and an original material thickness, 50 C.+/5 C., thermophilic conditions according to ISO 16929:2018-04 (modified only according to the temperature range set forth above), sieving of solids after six months in a sieve with 2 mm ash width (mesh 8.75), and when sieving less than 50 dry wt. % of the starting material remains in the sieve; or in a marine incubation test, with the following parameters: samples with a length of 2 cm, a width of 2 cm and an original material thickness, 30 C.+/2 C., aerobic conditions in seawater with a salinity of 3.5 wt. %+/1 wt. %, sieving of solids after twelve weeks in a sieve with 2 mm mesh (mesh 8.75), and when sieving after twelve weeks, less than 20 dry wt. % of the starting material remains in the sieve.

8. The geomaterial web according to claim 7, wherein the second structural material is a wood-based material.

9. The geomaterial web according to claim 7, wherein the second structural material is a wood-based, viscose-based fibrous material.

10. The geomaterial web according to claim 9, wherein the second structural material is lyocell.

11. The geomaterial web according to claim 1, wherein the second structural material is a wood-based material.

12. The geomaterial web according to claim 1, wherein the second structural material is a wood-based, viscose-based fibrous material.

13. The geomaterial web according to claim 12, wherein the second structural material is lyocell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments are explained with reference to the figures. They show:

(2) FIG. 1 is a schematic illustration of a use of the geomaterial web according to the invention in three different arrangements for coastal protection;

(3) FIGS. 2a and 2b are uses of the geomaterial web according to the invention for embankment stabilization at two different rooting times;

(4) FIG. 3 is a schematic representation of a first embodiment of the geomaterial web according to the invention;

(5) FIG. 4 is a schematic representation of a second embodiment of the geomaterial web according to the invention;

(6) FIG. 5 is a schematic representation of a third embodiment of the geomaterial web according to the invention; and

(7) FIG. 6 is a schematic representation of a fourth embodiment of the geomaterial web according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(8) The geomaterial web according to the invention can basically be installed in three different installation situations with respect to a water contact in the bank area. Starting from a natural shore area 2, which is bordered by the waterline or, in the case of tidal waters, by the average water level, and which may be protected against high water situations by an artificial dike 3, a geomaterial web can initially be used in an installation position A in order to stabilize the underwater terrain of the natural seabed course, in which stabilization of the soil with plants is only insufficiently possible. In this installation position A, the geomaterial web is usually submerged and can dry out in exceptional cases during low tide or strong waves.

(9) In a second installation position B, the geomaterial web is installed on the water side to stabilize the natural embankment and/or to stabilize the artificial embankment. In this installation position, the geomaterial web stabilizes the usually dry bank portion of the natural embankment and, where appropriate, the artificial embankment of the dike. It is, therefore, generally dry, but may also be immersed in flood situations or in the event of strong waves.

(10) In a third installation position C, the geomaterial web is used in an area, such as the back of the dike, in which it is not exposed to the water itself and can only be subjected to stress in special situations such as an overflow. In this installation position, the geomaterial web is therefore always dry and, as in any installation position, is only exposed to wetting by rainfall.

(11) Each of the three installation positions requires differently adjusted behavior of geomaterial webs in order to achieve ecologically favorable behavior. Thus, in installation position A, stability of the geomaterial web in the aqueous environment is required, but if, due to abrasive events, parts of this geomaterial web become detached and are, therefore, no longer in the place required to fulfill their function, degradation of these detached geomaterial web components is desired. According to the invention, this can be achieved, for example, by forming the geomaterial web from a material that is rapidly degraded under the influence of UV radiation. In this way, it is possible to ensure that torn parts of the geomaterial web that float up or are washed ashore are subjected to rapid degradation, whereas at the installation site, when the geomaterial web is not exposed to UV radiation, mechanical stability is maintained. Instead of specifying the geomaterial web to UV radiation, it is also possible, for example, to specify biodegradability as a function of the oxygen content of the water and/or the bacterial concentration and/or the fungal concentration in certain applications. This is particularly suitable when geomaterial webs are used at great ocean depths where, in particular, low concentrations of the aforementioned influencing parameters prevail. In this case, the material of the geomaterial web can be designed to be mechanically stable in the planned installation situation and in the surrounding water and to biodegrade as soon as the concentration of influencing parameters is increased in the surrounding water or at the shipment site.

(12) The installation situation according to C is relevant for the invention, for example, with regard to rooting and adaptation of the geomaterial web to rooting processes. FIGS. 2a and b show two successive rooting situations in which a geomaterial web 10 is installed to stabilize a soil layer 20 at a certain depth of the soil. As can be seen from FIG. 2a, the geomaterial web 10 has a high density with only small openings at an early stage, shortly after soil-stabilizing plants have been set, thereby providing a high degree of mechanical stabilization of the soil. The planted plants can penetrate the geomaterial web with small suckers and are not hindered in their growth. An effective mechanical bond between the geomaterial web and the plants is already achieved at this early stage.

(13) FIG. 2b shows the same installation situation after a few weeks of plant growth. The geomaterial web has partially decomposed mechanically due to biodegradation. It has larger openings and less mechanical stability. Due to the larger openings, the growing plants are not hindered in their rooting and the increase of the root diameters and can, therefore, take over the mechanical stabilization function. Therefore, with the geomaterial web according to the invention, a continuous shift of the mechanical stability of the soil layer from the geomaterial web to the plants is achieved, while maintaining a good mechanical connection between the plants and the geomaterial web, and the geomaterial web continues to have mechanical properties, possibly different in direction, and to assume functions for stabilizing the soil.

(14) FIGS. 3 to 6 show exemplary embodiments of a geomaterial web. In principle, the geomaterial webs according to the invention can be provided in different widths and lengths. Typical widths are greater than 1 m, 1.5 m, or 2 m and smaller than 4 m, 5 m, or 6 m and typical lengths are longer than 2 m, 5 m, 10 m, 50 m, whereby the geomaterial web is preferably transportable in rolled condition and is unrolled during installation. The thickness of the geomaterial web can be greater than 1 mm, thicknesses of more than 5 mm, 10 mm, or more than 20 mm are preferred. The geomaterial web may have a basis weight greater than 150, greater than 300, or greater than 500 g/m.sup.2. The basis weight may be less than 1500, less than 2000 g/m.sup.2, or less than 2500 g/m.sup.2.

(15) FIG. 3 shows a first embodiment with a top layer 110, a carrier layer 120, and a middle layer 130 arranged between the top layer 110 and the carrier layer 120. The top and carrier layers 110 and 120 may be made of different or the same materials and the middle layer 130 may be formed to the same way as the top layer and carrier layer or may be made of a material that is different therefrom.

(16) The top layer 110 and the carrier layer 120 are connected to each other by means of needling or sewing or knitting, for which purpose several needles 140a, 140b, 140c are 26 introduced into the geomaterial web, which connect the top layer 110 to the carrier layer 120 through the intermediate/middle layer 130. In this embodiment of a geomaterial web, the top layer 110 can, for example, be made of a material that biodegrades more quickly than the carrier layer 120. As a result, after partial or complete biodegradation of the needling or sewing or knitting portions of the geomaterial web, channels are formed that extend from the top to the bottom of the geomaterial web and, for example, provide space for root penetration or drainage effects. Thus, by said needling, the top layer material 110 and the carrier layer material 120 penetrate in said regions 140a,b,c through said intermediate/middle layer 130.

(17) FIG. 4 shows a second embodiment of a geomaterial web comprising an upper grid layer 210 and an underlying nonwoven layer 220. The grid layer 210 is formed by a crisscrossed grid of strong individual fibers or rods forming grid openings of a certain size, for example, 1010 mm to 4040 mm. The nonwoven layer is formed of dense, randomly oriented fibers of a different material to the layer 210. This nonwoven layer has the overall effect of closing the openings of the grid layer 210, resulting in an overall geomaterial web that is impermeable to coarser particles and has permeability to liquids and gases. The nonwoven layer 220 is made of a material such as lyocell and biodegrades faster than the grid layer 210. This reduces the mechanical strength of the geomaterial web within the short biodegradation time of the nonwoven layer 220 and, after degradation of the nonwoven layer 220, the geomaterial web is reduced to the remaining grid layer 210 with the openings formed therein, which, in turn, provide appropriate space for favorable root penetration. First perforation openings, namely the grid openings 210b in the grid layer 210 and a plurality of second perforation openings 220b in the second material, namely the nonwoven layer 220 are shown, with said first perforation openings being smaller than said second perforation openings.

(18) FIG. 5 shows a third embodiment, which is basically designed as a single-layer geomaterial web. In the geomaterial web, fibers 310 of a first material are arranged in a first direction and fibers 320 are arranged in a second direction transverse to the first direction, thereby forming respective fiber layers. The fibers 310 and 320 may be bonded together, for example, by welding, bonding, by looping, needling, weaving techniques, or knitting techniques, and/or by means of a cover and backing layer above and below the fibers 310 and 320. The fibers 310 are made of a different material than the fibers 320, and the material from which the fibers 320 are formed biodegrades more rapidly than the material from which the fibers 310 are formed. Due to this biodegradation behavior of the geomaterial web, the geomaterial web initially exhibits load capacity in the longitudinal and transverse directions corresponding to the course of the fibers 310, 320. As the biodegradation of the fibers 320 increases, the strength and load capacity in the longitudinal direction along the course of the fibers 320 decreases, resulting in an anisotropic mechanical load behavior of the geomaterial web.

(19) FIG. 6 shows a fourth embodiment in which two different materials are processed into a nonwoven layer that represents a geomaterial web or may represent a layer of a geomaterial web. The two different materials 410, 420 are processed unoriented as short or long fibers or continuous fibers to form a nonwoven web and are bonded together. The material 420 biodegrades faster than the material 410, causing the density of the geomaterial web to decrease as the biodegradation increases in the installation situation and causing the geomaterial web to become more permeable and/or change its mechanical properties.

(20) In principle, it is to be understood that the four embodiment examples may also be combined with each other by producing multi-layer geomaterial webs therefrom having combined properties of these embodiments. Furthermore, it is to be understood that the combination of the four embodiments can also be done in such a way that their properties are combined in a single layered geomaterial web, for example, by forming the lattice structure 210 of the second embodiment with the anisotropic biodegrading fibers 310, 320 of the third embodiment.

(21) The biodegradation behavior can basically be adjusted at the installation site and adapted to the conditions prevailing there. Thus, in all embodiments, the proportion of one material can be increased or decreased in relation to the proportion of the other material in order to obtain a desired biodegradation behavior in adaptation to the prevailing conditions. Furthermore, the biodegradation properties can be influenced or even first triggered by external influences, such as UV radiation and/or oxygen content and/or concentration of bacteria, fungi, or chemical influences of the environment, resulting in a specific behavior of the geomaterial webs with respect to biodegradation when they are moved from one location to another location where these specific environmental conditions change.