Flexible composite

Abstract

A flexible composite 200 comprising: a first layer; a second layer opposing the first layer and separated from the first layer by a space; a fill material 3 located in the space between the first and

Description

Technical Field

[001] This invention relates to new flexible composite material configured to join together. Technical Background

[002] Geosynthetic Cementitious Composite Mats (GCCMs) are a class of geosynthetic materials which are, in a most basic form, flexible concrete impregnated fabrics that can solidify upon hydration to create a thin, robust, and fire-resistant concrete layer, and an internal fibre matrix prevents crack propagation while offering reinforcement once set. They may be enhanced with a barrier layer such as a polymeric geomembrane backing on one surface to gain a fluid impervious barrier capability.

[003] The versatile nature of GCCMs means they can be used for many engineering applications such as for erosion control linings for water channels or for applications requiring formation of drainage or irrigation. Some other example uses for GCCMs includes being used to form: shelters as described in WO 2005 / 124063, track-ways (e.g. for vehicles), formworks for casting concrete, barriers (e.g. to line tunnels), repairs or reinforcement to structures, linings for ground works to prevent the leaching of chemical contaminants, or waterproof linings for the containment of water (e.g. ponds, canals, water storage, or settling or septic tanks).

[004] Some examples materials within the class of GCCMs are disclosed in WO 2007 / 144559 A2, WO 2010 / 086618 A2, and WO 2018 / 096333 Al.

[005] WO 2007 / 144559 A2 discloses a fabric comprising a pair of opposed faces and yarns (also called linking fibres) extending between the faces that maintain the faces in a spaced-apart arrangement and a solid powder material located in the space between the faces. The powder material is capable of setting to a rigid or semi-rigid solid mass on the addition of a liquid and may comprise cement that will set to solid cement or concrete on the addition of a water-based liquid.

[006] WO2010 / 086618 A2 discloses a cloth that has been impregnated with a material that, when mixed with a liquid, will set. The cloth of WO2010 / 086618 A2 prevents the fill material from spilling out of the edges of the cloth by providing an edge portion that extends laterally from one of the faces of the cloth and by elastic yarns which draw the extending portion towards the other face, thereby at least partly closing the space at the edge of the cloth and preventing fill material from spilling out of the cloth.

[007] The cloth of WO 2010 / 086618 A2 also provides an improvement over earlier impregnated cloths in that it provides a solution to the problem that it is difficult to control the amount of liquid that is added during the setting procedure. The cloth of WO2010 / 086618 A2 made it easier to control the amount of liquid that is added during the setting procedure by loading the cloth with a predetermined amount of fill, so as to only allow a predetermined amount of liquid into the cloth to set the reagent in the fill.

[008] WO 2018 / 096333 Al discloses a flexible composite that comprises a fill material between outer layers which is pressurised such that tension is applied to linking elements holding the first and second layers together and such that outwards bulges form between adjacent linking elements that are tensioned. The pressurised fill material in the flexible composite of WO 2018 / 096333 Al reduces movement of the fill material (and resulting loss of density) during transportation and installation of the flexible composite before being set and ensures the correct liquid to settable powder ratio during setting of the fill material.

[009] WO 2018 / 09633 Al discloses a fluid impervious element incorporated into one of the outer layers of the flexible composite. Preventing liquids such as water from passing through the flexible composite is advantageous for applications such as those mentioned above or where the surface the composite is laid on is very dry and wicks water out of the material during setting leading to a partial set finished product. A feature of the flexible composite disclosed in WO 2018 / 09633 Al is that the first and / or second layers may have textured keying surfaces abutting the fill material in the space and any other layers to improve the bonding strength between layers and to make the flexible composite more resistant to de-lamination when the set and exposed to external load.

[0010] GCCMs such as those described above are often manufactured at a width of approximately 1-5m and rolled up onto a roll which may then be stored until being transported to a customer. The width of produced GCCM is limited by the machinery being used. Often, the width of the produced GCCM is not large enough for the desired GCCM coverage and multiple rolled sections of GCCM must be joined together either end-to-end and / or side-by-side.

[0011] Known methods for joining GCCMs are limited and there is need for improved joining methods that provide more flexibility in how GCCMs can be laid.

[0012] Joining two GCCMs together may be done by overlapping a section of one GCCM onto another, and then using connecting means such as bolts, screws, clamps, and / or adhesive or melting of plastic elements to secure the two overlapping sections together before the GCCMs are set. This process can be repeated again and again to create large surface area coverage. This type of joining method can create a strong bond between two GCCMs especially once the GCCM has been set however depending on the intended application a different joining approach may be required. For example, if an application requires the creation of a fluid impervious barrier then the joining method discussed above is unlikely to provide the desired impermeability to fluid as the join formed is not adequately sealed and relies on the impermeability of the cementitious layer which may become cracked, furthermore it may be hard to test and certify joints in field use, particularly where there is a junction of two or more pieces.

[0013] To provide a continuous fluid impervious barrier between a pair of joined GCCMs (which are individually impermeable to fluids) a known approach is form an overlap of GCCMs along the desired joint where the underside of one GCCM piece is laid onto the top surface of the other GCCM along the length of the joint and the two layers are thermally bonded (which may also herein be referred to as 'welded') together using, for example, a hot-air welder such as a Leister Twinny S or T. One problem with this approach is that not all underside layers (e.g. a backing layer) are compatible or may be sub-optimally compatible with top surfaces for welding processes to enable the formation of a join by welding or if they are then the bonding formed may not achieve the desired impermeability to fluids.

[0014] An approach that could be used to avoid the above mentioned compatibility issue and achieve a high impermeability rating is to manufacture a GCCM with a layer bonded to the backside (a backing layer) that forms a fluid barrier layer such as a fluid impervious geomembrane (which may alternatively be referred to herein as 'membrane'), and configure the backing layer to have a section unbonded from the GCCM at one or both side edges meaning that at these points the GCCM can be peeled back, revealing a flap of only the barrier layer which may be overlapped with a flap of barrier layer from another similar GCCM and bonded together using a hot-air welder, thereby forming a continuous fluid impervious join between two GCCMs. Once the two flaps of barrier layer have been bonded then the other peeled back layers of the GCCM can be laid over the bonded joint before setting the GCCM. However, there are some problems with this approach.

[0015] One problem with this existing approach to joining is that due to restrictions in manufacturing processes it has only been possible to incorporate flaps for bonding at the sides and not at the ends of a roll of GCCM. Therefore, it is currently difficult to make end-to-end joins between rolls of GCCMs using this joining method. Where a side joint meets an end joint it is therefore necessary access the membrane backing layer which is on the underside of the two GCCM's in order to form an end or junction joint between the membranes or test the joint using a vacuum box or other standard on site test methods. To access the underside of the joint the heavy GCCM must be rolled over or lifted and this is very difficult and time consuming, particularly with large panels or junctions between more than two panels. Another problem with the existing approach to joining GCCM materials arises when GCCMs are cut at angles to create a desired shape; cutting a GCCM at an angle can cause the flap for bonding to be cut off leaving no flap available for bonding. Again, the GCCM must be turned upside down and a new flap (provided separately) welded on at the installation site then the heavy GCCM panel must be turned over again so that the membrane is below the GCCM (which protects the membrane) before it can be joined.

[0016] Another problem with the aforementioned flap approach for joining is that welding equipment such as a Leister Twinny S or T used to bond layers together generally requires some slack in the overlapping flap sections in order to weld properly. That is, current welding equipment cannot weld two sections together whilst the sections are completely flat against a surface. Having slack in order to weld sections together means that once a weld has been formed there is often an excess of material and the welded sections do not lie completely flat against the surface, since the weight of the two sections of GCCM either side of the join prevent redistribution of the material so that the material can lie flat. This issue is shown in Figure la and can be referred to as 'tenting'. Tenting is a problem for the aesthetics and performance of joined GCCMs; when a tented bonded backing layer surface is pushed down against the ground (e.g., when someone walks on it and / or presses and sets the GCCM over the top of it) a crease often forms as shown in Figure lb. These creases in the geomembrane can be vulnerable to stress cracking which would compromise the GCCM's ability to act as a fluid barrier (as shown in Figure lc, where the crease has split).

[0017] A potential solution to the aforementioned problems is to lay a GCCM over an unattached fluid barrier, such as a geomembrane. However where the barrier layer is not bonded to the GCCM layers the barrier layer is free to expand and contract due to temperature fluctuations without the constraint of being attached to the GCCM layers, and expansion of the barrier layer can lead to rupturing of the join formed between GCCMs and / or cause the layers of GCCM above to raise up from the surface it has been laid against, sometimes creating wrinkles along the longitudinal or transverse direction of the GCCM.

[0018] The present disclosure aims to provide a flexible composite which solves or at least alleviates one or more of the problems discussed above.

[0019] The term "flexible composite" or "composite" will be used in the present specification to denote a composite material comprising a spacer material comprising an internal space containing a fill material. A "spacer material" is a material having a first layer and a second layer separated from each other by an inner space and also has linking elements extending between the first and second layers that maintain the first and second layers in a spaced-apart arrangement. The fill material will also be referred to as the "fill"; the fill may be a settable fill and if so may include both material that reacts with the liquid, gas, or radiation to cause the fill to set, which will be referred to as the "reagent", and materials that do not react with the liquid or radiation, e.g. auxiliaries and inert materials such as fillers. The term "first layer" will denote the portion of the composite between the topside outer face and internal space. This first layer may be liquid, gas, and / or radiation permeable and would normally be the uppermost part of the product in an installation. The term "element" will be used to denote a discrete material component, which may be combined with other elements to form the product layers. The first layer may consist of more than one individual elements bonded together (which could also be referred to as one or more additional functional layers to provide specific functionality such as a reinforcement element to provide reinforcement to the first layer). The term "second layer" will denote the portion of the composite between the internal space and the underside outer face. This second layer would normally be the side that would not be exposed to weathering once installed. The second layer may also consist of multiple individual elements bonded together (which could also be referred to as additional functional layers to provide specific functionality such as a reinforcement element to provide reinforcement to the first layer). That is, the first and second layer may individually comprise several layers (e.g. 2, 3, 4, 5, 6, 7, 8 etc layers) bonded together. The term "longitudinal" as used herein in relation to a direction along a flexible composite is used to denote the machine direction of the flexible composite (that is, the length of the flexible composite). The term "transverse" as used herein in relation to a direction along a flexible composite is used to denote the width direction (cross direction) of the flexible composite. SUMMARY OF INVENTION

[0020] In a first aspect there is provided a flexible composite comprising: a first layer; a second layer opposing the first layer and separated from the first layer by a space; a fill material located in the space between the first and second layers; a plurality of linking elements within the space which join the first and second layers together; and a third layer attached to the first layer or the second layer at two or more discrete spaced apart attachment points, thereby defining a flap in the third layer between one or more edges of the third layer and the attachment points, the flap for use in joining the flexible composite to another surface.

[0021] The 'another surface' referred to could be a surface which is not part of the flexible composite of the first aspect (but which is compatible to be joined with the flap) and also extends to the flap(s) of one or more other flexible composites in accordance with the first aspect. The 'another surface' referred to could also extend to the surface (flap) on an opposing edge of the same flexible composite (e.g. to produce a cylindrical / tubular shape or a cone shape with a single flexible composite).

[0022] Optionally, the third layer comprises a heat bondable material thereby making the flap a heat bondable flap for joining the flexible composite to another surface by heat bonding.

[0023] Optionally, when the flexible composite is laid on a flat surface the third layer is substantially contiguous with the first or second layer it is attached to.

[0024] Optionally, the first layer, the second layer, and the third layer are substantially the same dimensions in terms of length and width.

[0025] Optionally, the third layer extends beyond one or more edges of the first layer and second layer thereby enlarging the size of the flap at said edges of the flexible composite. Optionally the third layer extends beyond one or both sides of the first layer and second layer thereby enlarging the size of the flap at one or both sides of the flexible composite. Alternatively, the dimensions of the third layer may be smaller than those of the first layer and second layer in terms of length and width. The relative size of the third layer with respect to the size of the first and second layers can be controlled to provide a desired surface areas for bonding when joining the flexible composite to another.

[0026] Optionally, the attachment points are arranged along one or more longitudinal and / or transverse axes of the flexible composite.

[0027] Optionally, the discrete spaced apart attachment points are arranged in a line along a length of the layer to which the third layer is attached, preferably forming a straight line of spaced apart attachment points.

[0028] Optionally, the discrete spaced apart attachment points are arranged in two or more lines along a length of the layer to which the third layer is attached, preferably forming two or more straight lines of spaced apart attachment points.

[0029] Optionally, the discrete spaced apart attachment points of neighbouring lines are offset with respect to each other.

[0030] Optionally, the discrete spaced apart attachment points are substantially circular, square, rectangular, rhombic or triangular in shape, preferably the attachment points are substantially circular in shape.

[0031] Optionally, the discrete spaced apart attachment points are substantially circular with a diameter from 0.005 - 2m, preferably from 0.05 - 0.5m, and more preferably 0.2 - 0.4m.

[0032] Optionally, the spacing between the nearest point of a neighbouring attachment point is from 0.01 - 5m, preferably from 0.2 - lm, and more preferably from 0.2 - 0.5m.

[0033] Optionally, the discrete spaced apart attachment points are symmetrically centred along a longitudinal and / or transverse axis of the flexible composite with respect to sides of the flexible composite.

[0034] Optionally, the total surface area of the attachment points is 1 - 60% of the surface area of the layer the third layer is attached to, preferably 1.5 - 30%, more preferably 2 -10%.

[0035] Optionally, the peel strength between of the attachment points is configured to be lower than the shear strength of the attachment points. The peel strength is the extent to which the bond resists peeling. That is, the extent to which the bond between the third layer and the layer it is attached to resists peeling (at the attachment points). The peel strength between the attachment points may be configured to be lower than the shear strength of the attachment points by controlling the attachment conditions while the flexible composite is being manufactured. These attachment conditions may comprise the temperature at the moment of joining the third layer to the first or second layer, the pressure at which they are pushed together and the rate of cooling after they have been pushed together, and / or the type of adhesive used, in order to achieve a desired peel strength.

[0036] Optionally, the peel strength of the attachment points is between 1 - 25 times lower than the shear strength of the attachment points, and preferably 1 -10 times lower.

[0037] Optionally, the peel strength of the attachment points is from 0.5 - 20 kN / m, and preferably 0.5 - 10 kN / m. For example, the peel strength may be 0.5,1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 kN / m.

[0038] Optionally, the shear strength of the attachment points is less than or equal to the tensile strength of the layer (the first layer or the second layer) which the third layer is attached to. Optionally, the shear strength of the attachment points is from 5-40 kN / m, preferably 10 - 35 kN / m and more preferably 10 - 25 kN / m. For example, the shear strength may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 kN / m, or may be between 5 kN / m and the tensile strength of the layer which the third layer is attached to.

[0039] Optionally, the third layer comprises at least two sub-layers and wherein the sub-layers may be of the same material or different materials.

[0040] Optionally, the third layer and the first or second layer it is attached to have substantially the same melting points at least at the attachment points.

[0041] Optionally, the third layer has a lower melting point than the melting point of the first or second layer it is attached to has at least at the attachment points.

[0042] Optionally, the third layer forms a continuous membrane which is substantially impervious to liquids.

[0043] Optionally, the third layer comprises a thermoplastic.

[0044] Optionally, the third layer comprises a polymeric material. Optionally, the third layer comprises a low-melt polymer, polyvinyl chloride, polypropylene, a hot melt extrusion, polyethylene, flexible polypropylene, chlorosulphonated polyethylene, polyurethane, EPDM rubber, butyl rubber, neoprene®, polyuria coatings, silicone, latex, natural or synthetic rubbers, or mixtures thereof.

[0045] Optionally, the third layer comprises polyethylene and preferably high-density polyethylene, medium density polyethylene, and / or low-density polyethylene such as linear low-density polyethylene. Optionally the third layer is a geomembrane.

[0046] Optionally, the fill material is a powder, a paste or a foam, preferably the fill material is a powder.

[0047] Optionally, the fill material between the first and second layers is capable of setting to a rigid or semi-rigid solid on the addition of a liquid, gas or radiation.

[0048] Optionally, the fill material comprises cement. Optionally, the fill material comprises one or more of a settable fill material such as but not limited to: Portland cement, high alumina cement, cement-aggregate mix, lime-aggregate mix, calcium sulphates, calcium fluorites, calcium silicates, plaster, calcium aluminate, magnesium cements, or mixtures thereof. Preferably, the settable fill material comprises Portland cement or high alumina cement. The cement may be combined with additives customarily found in cement or concrete compositions such as fillers or reaction modifiers.

[0049] Optionally, the fill material comprises water swellable materials such as bentonite clay, super absorbent polymer(s), modified acrylic resin(s), oil swelling elastomer(s), or mixtures thereof.

[0050] Optionally, the fill material comprises a high-density porous fill material such as sand and / or aggregates.

[0051] Optionally, the fill material comprises a first fill material capable of setting to a rigid or semirigid solid on the addition of a liquid, gas or radiation; and a second fill material in the space comprising: a water swellable material such as bentonite clay, super absorbent polymer(s), modified acrylic resin(s), oil swelling elastomer(s), or mixtures thereof, and / or a high density porous material such as sand and / or aggregates; and wherein the flexible composite further comprises a separation layer configured to separate the first fill material from the second fill material in the space.

[0052] Optionally, the first and / or second layers comprise a non-woven fabric, woven fabric, knitted fabric, or extruded layer. Preferably the first and / or second layers comprise non-woven fabric.

[0053] Optionally, if the first and / or second layers comprise a non-woven fabric then the non-woven fabric of the first and / or second layers comprises one or more of polypropylene fibres (e.g. polyethylene terephthalate fibres), polyester fibres, polyvinyl alcohol fibres, nylon fibres, silnylon fibres, vinyl fibres, basalt fibres, carbon fibres, alkaline resistance fibreglass fibres, glass fibres, coated glass fibres, polyvinylchloride (PVC) fibres, aramid fibres, and natural fibres (e.g. jute, cotton, and viscose fibres). Preferably, the non-woven fabric of the first and / or second layers comprises one or more of polypropylene fibres, polyester fibres, nylon fibres, PVC fibres, glass fibres, natural fibres, soluble fibres and basalt fibres. Preferably, the non-woven fabric of the first and / or second layers comprises polypropylene and / or polyester fibres. The fibres may additionally comprise a thermally activated bonding agent or other forms of bonding agents that rely on chemical activation, radiation activation, or oxidisation activation.

[0054] Optionally, the first layer is permeable to gases and liquid, but substantially impermeable to the fill material.

[0055] Optionally, the second layer is substantially impermeable to the fill material.

[0056] The optional features described herein may be taken in any combination with the essential features of the invention. BRIEF DESCRIPTION OF DRAWINGS

[0057] The above and other aspects will now be described, by way of example only, with reference to the accompanying figures, in which: Figures la to lc show the principle of tenting and creases that have been found to form when joining GCCMs comprising a fluid barrier using known methods; Figure 2 shows a perspective view of an example flexible composite of the present invention; Figure 3 shows a cross-section view of a component of the flexible composite shown in Figure 2; and Figures 4 to 6 show some example arrangements of attachment points and cutting options for example flexible composites of the present invention. DETAILED DESCRIPTION

[0058] The following is a description of an example flexible composite in accordance with this disclosure.

[0059] A first example of a flexible composite material in accordance with this disclosure is shown in Figure 2 generally at item 200. Flexible composite material 200 is made up of a mat component 202 which is flexible and in this example can be set to become rigid or semi-rigid upon addition of a liquid, gas or radiation. Flexible composite 200 also has a fluid barrier layer 204 attached to the mat component 202 at attachment points 206 which may alternatively be referred to as nodes 206.

[0060] The orientation of the flexible composite material 200 in Figure 2 is such that the fluid barrier layer 204 is facing upwards on top of the mat component 202. In practice however, typically the fluid barrier layer 204 would be a bottom layer abutting the surface over which the flexible composite material 200 is to be laid. Mat component (202)

[0061] Figure 3 shows the composition and make-up of the mat component 202, which has a first layer (a), a second layer (c), and a space (b) between the first and second layers. The space (b) comprises a fill material 3 and linking elements 2.

[0062] Whilst detail of the mat component 202 shown in Figures 2 and 3 will now be described in the following paragraphs in relation to example flexible composite 200 it should be understood that mat component 202 could be replaced with a different spacer material containing a fill material; that is, mat component 202 could be replaced with a spacer material having a first layer and a second layer opposing the first layer and separated from each other by an inner space comprising a fill material and also having linking elements extending between the first and second layers that maintain the first and second layers in a spaced-apart arrangement.

[0063] The structure of mat component 202 is achieved by impregnating the fill material 3 under positive differential pressure in-between the first layer (a) and second layer (c) whilst positioning the linking elements 2 in the space (b) to extend between said layers using the needle punching or stitching techniques disclosed below.

[0064] The first layer (a) is a fibre donating layer 1 made of a needle punched polypropylene nonwoven fabric which is firstly capable of containing the fill material 3 in the space (b) between the first and second layers, and secondly is selectively permeable to certain fluids e.g. permeable to liquids and gases but not substantially to the fill material 3. The second layer (c) is made from the same material as the first layer (a) although this is not essential.

[0065] The linking elements 2 of mat component 202 are polypropylene fibres that have been extended out from the non-woven fabric of first layer 1 and extend through the space (b) with a net angle of approximately 90 degrees to layers (a) and (c) so as to be substantially perpendicular to the longitudinal axis of said layers. The needling punching technique used to create the linking elements 2 uses barbed needles to pick up fibres from the non-woven polypropylene of layer (a) and carry / extend them through the space (b) and substantially over to the second layer (c).

[0066] The fill material 3, when unset, is provided in the space (b) at a pressure such that tension is applied to the linking elements 2. The pressure of the fill material 3, and a lack of longitudinal stretch of the fibres under tension, causes the first and second layers to bulge outwards relative to the longitudinal length of the fibres under tension. In other words, the first layer (a) and second layer (c) outwardly extend beyond the linking elements 2 in the direction of the net longitudinal axis of the linking elements 2.

[0067] The amount / extent of which the first layer (a) and / or the second layer (c) bulge out due to the pressurised fill material 3 depends on the material properties of the fibres and the first layer (a) and second layer (c). For example, the stiffness of the first and / or second layers may be increased to reduce the amount of bulging, or even increased on one or both of the layers so that the bulging is prevented altogether. The material properties of the first layer (a) and the second layer (c) may be varied so as to obtain bulges of different sizes when the fill material is present in the space under pressure.

[0068] Figure 3 shows a cross section through the three-dimensional microstructures of mat component 202 created by filling the fill material 3 under positive differential pressure, deforming the first layer (a) and second layer (c), with the linked elements 2 forming the minima of the shape thus formed.

[0069] Once the linking elements 2 have passed through and exited the second layer (c) due to the needle punching, their primary direction changes from being substantially perpendicular to the longitudinal axis of the first layer (a) and the second layer (c) to being substantially parallel to said longitudinal axis of layers (a) and (c). The parts of the linking elements that have changed direction are configured to substantially conform to the bulging surface of the second layer (c). After this change of direction, the linking elements protruding out of second layer (c) may be bonded to the second layer (c) using an adhesive layer (not shown in Figure 3), thereby providing a mechanical join between the first layer (a) and second layer (c). That is, the linking elements 2 join the first and second layers together.

[0070] The fill material 3 in mat component 202 may be any material that is capable of setting to a rigid or semi-rigid solid upon the addition of a liquid, when exposed to UV radiation or a gas such as air. For example, the fill material may comprise cement. Cement may be used together with fillers and other additives such as reaction modifiers.

[0071] The fill material 3 may be selected from one or more of a powder, a paste, or a foamable composition. Preferably, the fill material 3 is a cement mix. For example, the fill material may comprise one or more of a settable fill material such as but not limited to: Portland cement, high alumina cement, cement-aggregate mix, lime-aggregate mix, calcium sulphates, calcium fluorites, calcium silicates, plaster, calcium aluminate, magnesium cements, or mixtures thereof. Preferably, the settable fill material comprises Portland cement or high alumina cement. The cement may be combined with additives customarily found in cement or concrete compositions.

[0072] The fill material 3 may comprise a filler material as mentioned above. The filler material may comprise sand or fine aggregates, fly ash, glass beads, low density or recycled fillers, chopped natural or synthetic fibres, lime flour, limestone, mica insulators, surface modified silica, impact modifiers, expandable microspheres, thermally conductive particles, merakaolin, electrically conductive particles, silica, clay, talc, colorants, super absorbent polymers, antioxidants, antimicrobial agents, surfactants, fluropolymers, pigments, biocides such as anti-fungal or antimicrobial agents and antiradiation fillers, or any mixtures thereof.

[0073] One or more of the above-described filler materials may be used to reduce the weight and / or cost of the resulting mat component 202, modify the thermal properties, or confer a range of physical properties derived from the physical property activity of the filler material, including electrical, optical, liquid barrier etc.

[0074] The fill material 3 may comprise reaction modifiers. The reaction modifiers of the fill material 3 may comprise lithium compounds, sodium compounds, organic compounds (citric acid, tartaric acid), sulphate sources, plasticisers, accelerants, retarders, super plasticisers, shrinkage reducing agents waterproofing agents, pH modifiers, glass beads, pozzolanic materials, foaming agents, dispersible polymer powders, or mixtures thereof.

[0075] Mat component 202 may be made using the following example techniques:

[0076] Firstly, the first layer (consisting of a needle punched polypropylene non-woven fabric) and the second layer (consisting of a woven polypropylene tape, coated with low melt on its outer face and with a needle punched polypropylene nonwoven bonded to its inner face) are drawn into a needle loom. For example, a loom which can produce material up to 10 m in width. The loom has a series of long tubes running in the machine direction (MD) (i.e. in the production direction of the mat component 202) fixed between a loom bed and stripper plates. The tubes are positioned between the stripper plates and the loom bed so as to leave a gap either side of the tubes. The bed and stripper plates are separated by a gap of between 3 and 100mm. The first layer is drawn through the loom between the tubes and the stripper plate. The second layer is drawn through the loom between the tubes and the bed plate, with the tubes forming a sandwich between the two layers. The tubes have an outer diameter between 3 and 25 mm and are aligned at a spacing in the cross direction (the transverse direction which is 90 degrees from the MD) of between 4 and 50 mm, the tubes may be of a non-circular cross section and / or may be stacked. The thickness of the final mat component 202 is dependent on both the size of the gap between the bed and stripper plates, and on the diameter of the tubes. The thickness of the mat component 202 (once filled) may be between 3 and 50 mm.

[0077] Secondly, the needles of the needle loom are aligned such as to strike between the tubes. The stripper plate and loom bed comprise holes or slits, which are aligned so as to receive the needles and allow them to pass through during the strike action. Needles striking repeatedly in this manner push fibres from the first layer, across the gap between the tubes and through the second layer, with the ends of the fibres projecting from the outer face of the second layer between 0.1 and 30 mm. The spacing in the machine direction of the linking elements thus formed is between 0.5 and 20 mm. The spacing in the transverse direction is fixed as a multiple of the spacing of the tubes, which may be evenly or irregularity spaced, with even or irregular gaps between them. As the material is drawn through the needle loom, at a line speed of between 0.1 and 50 m / min it slides over the fixed tubes. The needles can be set to strike at any angle so long as the needles do not strike the tubes.

[0078] Thirdly, at a location between the needle loom and the downstream end of the tubes, a heater (hotair, conductive, radiative, high frequency etc.) and a pressure roller act upon the outer face of the second layer to activate the low melt layer and glue down the ends of the linking fibres protruding from the outer face of the second layer. Alternatively, or additionally, the above heating method may be used to shrivel or bond the protruding fibre ends to prevent pull-out.

[0079] Fourthly, a protective element (consisting of a needle punched polypropylene nonwoven) may be added to the outer face of the second layer. It is preferable to introduce this at the same position in the line as the heater so that the same low melt adhesive which glues down the linking fibre tufts also adheres to the protective layer.

[0080] Fifthly, the tubes extend from the needle loom a distance in the machine direction from between 0.1 m and 20 m. These tubes are connected at the upstream end to a pressure vessel containing pressurised settable powder fluidized with compressed air, with a particle size small enough to pass through the tubes. This settable powder is blown down the tubes and exits into the gap between the first and second layers. The settable powder is under a positive differential pressure when it exits the pressure vessel of between 0.1 and 50 bar, and is compacted as it enters the gap between the first and second layers. One of these layers acts as a filter to allow the air to leave the material. Stacked tubes (with a separation element introduced between them) may be used to introduce a second layer of a non-settable powder.

[0081] Optionally, the edges of the mat component 202 are sealed to prevent the fill material from escaping. The edges of the mat component 202 may be sealed before introduction or after introduction of the fill material, but preferably before introduction of the fill material. The edges of the mat component 202 may be sealed by way of elastic yarn, stitching, ultrasonic bonding, thermal bonding, needle punching, or adhesive.

[0082] The two primary layers (the first layer (a) and the second layer (c)) of the mat component 202 produced by the manufacturing method set out above are linked by fibres originating from one of the primary layers using a needle punching machine (a needle loom). However, these linking fibres could originate from elsewhere, such as a yarn introduced into a stitch bonding machine. The manufacturing sequence above would be identical in the latter scenario, with the exception that the first and second layers would be drawn into a stitch bonding machine rather than a needling machine. The width of the mat component cloth, thickness, line speed, linking fibre spacing, etc. would remain unchanged. The key difference is that the reciprocating needles would be carrying yarn from an external reel between the two layers thereby joining them, rather than barbed needles picking up fibres from one of the layers to create the linking fibres. Alternatively, the material may be loaded by needling through the bulk powder under hydrostatic pressure. Alternatives to mat component 202

[0083] As mentioned above, the mat component 202 is not limited to the mat described above or limited to mats made by the approach described above in relation to mat component 202 and may include mats made by other methods of making GCCM's and other geosynthetic ballasting, sealing or protection mats. For example, mat component 202 could be filled spacer fabrics or geosynthetic mats made using a process used to form geosynthetic clay liner materials (such as a bentonite geosynthetic clay liner comprising two geotextile layers that are needle punched together, encapsulating a layer of bentonite clay granules between them), but adapted so that needling is carried out between one or multiple actively needleable non-woven(s) and a non-woven or woven fabric where the layer of bentonite clay granules between the two layers has been replaced by a layer of granular or power fill material (which may be an unset cementitious material) and which is trapped by the fibres that are dragging through the granular or powder fill material from a donor layer and through the second layer or vice versa to form linking elements by the needling process.

[0084] The mat component 202 is not limited to a mat which can set to become rigid or semi-rigid as described above and as shown in Figures 2 and 3. The mat component 202 may alternatively be any other material with the same or similar structure (i.e. a spacer material, or geosynthetic clay liner type material) but with a fill material 3 which does not set to become rigid or semi-rigid. For example, the fill material 3 of mat component 202 may be a fill material which provides high levels of fluid impermeability, for example by employing swellable materials. Water or oil swellable fill materials may be used to selectively prevent passage of certain liquids or contaminates through a surface. The fill material 3 may comprise water swellable materials such as bentonite clay, super absorbent polymers, modified acrylic resins, oil swelling elastomers, or mixtures thereof. The mat component 202 may be any geosynthetic material.

[0085] The mat component 202 may also be composed of multiple functional layers for example an upper cementitious protection layer and a lower bentonite sealing layer. For example, the mat component 202 may be provided with an additional second fill material (not shown in the figures) which is located in the space (b) and separated from the fill material 3 by way of a separation layer, thereby defining a first fill material layer (of the fill material 3) and a second fill material layer. The first fill material layer can be a settable fill, as described previously. The second fill material may be a settable fill material that is similar to the first fill material, but this is not essential and the second fill material may also be non-settable material, for example a fluid swellable substance, such as bentonite clay, super absorbent polymer(s), modified acrylic resin(s), oil swelling elastomer(s), or mixtures thereof, or may comprise (in addition or instead) a high density porous fill material such as sand and / or aggregates.

[0086] The separation layer may be made from non-woven polypropylene, which is permeable to liquids such as water. As such, when a liquid (e.g. water) is applied to the flexible composite, the separation layer allows the water to seep through the first fill material layer to the second fill material layer, thereby allowing both fill materials to be hydrated but preventing substantial mixing of the two fill materials when dry or wet.

[0087] The separation layer is not limited to being made from non-woven polypropylene, and made alternatively be any other suitable material fabric which can separate the two fill materials and is permeable to liquids such as water.

[0088] Further separation layers may be incorporated into the flexible composite to add third, fourth, fifth etc. fill material layers if desired, and these can provide additional functionality such as electrically conductive sensing layers or reinforcement layers, including grids, to improve the stiffness or strength of the composite in a hardened (rigid or semi-rigid) or soft (flexible) state or include high temperature reinforcement elements such as fabrics or grids made from basalt fibres. The fluid barrier layer 204

[0089] The fluid barrier layer 204 is attached to the mat component 202 (as a third layer 204) at discrete attachment points 206. The purpose of the fluid barrier layer 204 of flexible composite material 200 is to provide a layer which is impervious to fluids. Another function of the fluid barrier layer 204 is to serve as a surface for joining one piece of flexible composite 200 to the fluid barrier layer of another piece, thereby forming a continuous fluid barrier layer across the join. The fluid barrier layer 204 may therefore be any suitable material which provides a surface that can be attached to the mat component 202 at the attachment points 206, provides the desired fluid barrier properties, and may be welded to the surface of another material through heat treatment whether that be of the same material composition or a different compatible material. A preferred material for fluid barrier layer 204 is a polyethylene sheet such as a polyethylene geomembrane (e.g. a LLDPE geomembrane) which acts as a fluid impervious layer, is suitable for welding to another polyethylene sheet, and may be bonded to mat component 202 using strategically deployed localised heat treatment during the manufacturing process which is covered in more detail below.

[0090] The fluid barrier layer 204 is added to the second layer (c) of mat component 202 after mat component 202 has been manufactured. Fluid barrier layer 204 is rolled on top of mat component 202 and attached at attachment points 206 by heat bonding treatment, using one or more localised heat treatment guns to heat the surface of the fluid barrier layer 204, followed by using one or more rollers to press the mat component 202 and fluid barrier layer 204 together at the area that was heated, thereby forming the attachment point 206 between the layers. The rollers may be positioned above the fluid barrier layer 204 to press layers 202 and 204 together (i.e. one sided rollers) or above the fluid barrier layer 204 and below the mat component 202 to press the layers together (i.e. two sided rolling).

[0091] A radial deployment of heat from a heat gun can be used to create substantially circular attachment points, however the heat deployment pattern can be adjusted to create attachment points 206 of different shapes, e.g. substantially square, rectangular, triangular, rhombic etc.. The invention is not limited to the type of shapes that may be used for the attachment points but circular is generally preferred. Preferably sharp edges / corners on the shape of the attachment points 206 are avoided as they can be areas susceptible to initiation of undesirable peeling and therefore, preferably, the corners on any shapes comprising edges e.g. squares, rectangles, triangles, rhomboids etc. comprise radiused corners. The heat gun may be located above layers 202 and 206. Providing a non-woven second layer (c) which has a rough fibrous surface helps to provide a good bond with the fluid barrier layer 204. The fluid barrier layer 204 may alternatively be attached at the attachment points 206 by use of an adhesive layer between fluid barrier layer 204 and mat component 202. The pressure applied by the roller(s) onto layers 202 and / or 204 should be suitable pressure to form the desired bond between the layers given the nature of the heat or adhesive applied. Typically, the operating conditions for applying heat using this method will vary, e.g. depending on the materials used, distance between the heat source (the heat gun), and desired bond strength between layers. When using a thermoplastic sheet as the barrier layer 204 it should preferably be heated so that the surface of fluid barrier layer 204 that is pressed into component 202 is between the melting point and glass transition temperature of the mat component 202. An increased rate of production may be obtained if the fluid barrier 204 is cooled by for example chilled rollers after the layers have been pressed together.

[0092] Other methods of forming nodes 206 may include but are not limited to lamination and direct extrusion.

[0093] It has been found that by controlling the fluid barrier layer 204 attachment conditions, primarily the temperature at the moment of joining, the pressure at which they are pushed together and the rate of cooling after they have been pushed together, or the type of adhesive used, it is possible to adjust the peel strength of the join at the attachment points 206 to achieve a desired peel strength. The peel strength is the extent to which the bond resists peeling. For example, ensuring that the temperature of the fluid barrier layer 204 at the moment of joining is above the melting point of the mat component 202 increases peel strength, reducing pressure at which the layers are pushed together reduces the peel strength (especially if adhesive is used), and matching the thermal shrinkage strain of the fluid barrier layer 204 at the moment of joining with the strain the mat component 202 is under at the point of joining results in high bond strength (and vice versa). Using the methods disclosed herein it is possible to produce nodes with a relatively weak attachment in peel but a stronger attachment when loaded in shear (that is, a lower peel strength relative to the shear strength). This can be advantageous as in some circumstances it may be useful to be able to peel layer 202 away from fluid barrier layer 204 onsite to increase the range of angles that may be cut while still having a sufficiently large flap available for welding.

[0094] Depending on the intended use of the flexible composite it can be advantageous if the surface of mat component 202 is formed from a plastic that is the same or has a similar (i.e. substantially the same) melting point to the fluid barrier layer 204 so that if and when the node is peeled apart a thermal weld formed in fluid barrier 204 across the peeled node will also fuse any inclusions of fibres from the mat component 202, preventing them from compromising weld strength. That is, good bonding can be achieved across the weld even if there are inclusions of fibres from mat component 202 present given any included / encapsulated fibres will participate in the welding action.

[0095] For some uses and depending on the materials used to form mat component 202 it may be advantageous to configure the surface of mat component 202 to have a different melting point to the fluid barrier layer 204, for example so that the surface of mat component 202, if formed from a plastic, has a higher melting point than the fluid barrier layer 204 - this means that the tensile strength of the mat component 202 is not altered or substantially altered through thermal treatment by melting parts of it during bonding of the fluid barrier layer 204 to it during production of the flexible composite, and accordingly that the surface of the mat component 202 at the attachment points is less likely to tear if and when an attachment point 206 is peeled apart. Formation of the attachment points 206 would still be possible as during the heat treatment to form them the fluid barrier layer 204 would melt and mechanically key into the surface of the mat component 202 even if the surface of mat component 202 has not melted.

[0096] Preferably, the peel strength of the bonds formed at the attachment points 206 between the mat component 202 and fluid barrier layer 204 (i.e. the peel strength between the mat component 202 and the fluid barrier layer 204 at the attachment points 206) is from 0.5 - 20 kN / m, preferably 0.5 -10 kN / m, and more preferably 3-6 kN / m, when tested using BS EN ISO 13426-2:2005.

[0097] Preferably, the shear strength of the bonds formed at the attachment points 206 between the mat component 202 and fluid barrier layer 204 (i.e. the shear strength between the mat component 202 and the fluid barrier layer 204 at the attachment points 206) is less than or equal to the tensile strength of the outer layer of the mat component 202 in contact with the fluid barrier layer 204 (the second layer (c)). The shear strength of the bonds formed at the attachment points 206 between the mat component 202 and fluid barrier layer 204 may be from 5 - 40 kN / m, preferably 10 - 30 kN / m, and more preferably 10-20 kN / m, when tested using BS EN ISO 13426-2:2005.

[0098] As mentioned in the preceding paragraphs, the required functionality of the fluid barrier layer 204 is to (1) act as a fluid barrier, (2) attach to mat component 202, and (3) to provide a suitable bonding surface for bonding to another piece of flexible composite. As mentioned above, the flexible composite 200 is one example of the present invention and if providing fluid barrier properties is not necessary then the material chosen to be attached to the mat component 202 may not have to have fluid barrier properties so long as it can (1) be attached to mat component 202 (e.g. using the techniques disclosed herein or other known techniques) and (2) provide a suitable bonding surface for bonding to another piece of flexible composite. The attachment points 206

[0099] The fluid barrier layer 204 is attached to mat component 202 only at discrete attachment points 206 which are generally circular in shape. The dashed sections in Figures 2, 4, 5 and 6 at attachment points 206 show the areas of adhesion. There is no adhesion between the mat component 202 and the fluid barrier layer 204 apart from at the attachment points 206, which means that as the flexible composite material 200 is laid on a flat surface (in the orientation depicted in Figure 2, or in an opposite orientation where the mat component 202 is on top of the fluid barrier layer 204) the two layers (202 and 204) are substantially contiguous with each other, but may be peeled apart around the attachment points 206. Peeling mat component 202 away from fluid barrier layer 204 creates a flap section of the fluid barrier layer 204 suitable for bonding to a similar bonding flap of another piece of flexible composite material 200.

[00100] It has been found that arranging the attachment points 206 as discrete spaced apart nodes enables the fluid barrier layer 204 to be carried and rolled up together with the mat component 202 after manufacture and be transported to a customer where it may be unrolled for deployment whilst holding layer 204 and mat 202 in their correct positioning with respect to each other, whilst also enabling the provision of welding flaps at the ends of the flexible composite even if cut to size along the flexible composite's width (i.e. along the cross-direction) so long as the cut is made between nodes. The arrangements of attachment points 206 disclosed herein also enables a user to make angled cuts to the flexible composite 200 whilst still having flap sections available for bonding to form a join with another flexible composite 200.

[00101] It has been found that the arrangement of attachment points 206 disclosed herein also advantageously and surprisingly reduces the problems of tenting at join locations and wrinkling resulting from expansion of the fluid barrier layer 204 after the join has been formed and the flexible composite set. One reason is that the limited and controlled spacing between the nodes limits the length of any expansion of the fluid barrier 202 and hence the maximum size of wrinkles that can form.

[00102] The attachment points 206 are not limited to the arrangement shown for flexible composite 200 in Figure 2 where there is one symmetrically centralised line of spaced apart attachment points along the longitudinal length of the flexible composite 200. There may for example be two or three or four rows of attachment points depending on the width of the flexible composite. The size and pattern of the nodes used will determine the angles that can be cut while maintaining an offset distance from the nodes to enable suitable flats (preferably greater than 100mm long) to be formed.

[00103] Figures 4 to 6 show various arrangements of attachment points 206 with some examples of possible cutting lines denoted with letters (e.g. Figure 4 shows an angled cutting line from A to B, and Figure 5 shows several cutting lines from A to B, C to D, and E to F).

[00104] Figure 5 shows a flexible composite 500 which is the same as flexible composite 200 apart from the location of the attachment points 206 which are set out in two symmetrically centralised lines of spaced apart attachment points along the longitudinal length of the flexible composite 500.

[00105] Figure 6 shows flexible composite 600 which is the same as flexible composite 200 apart from the location of the attachment points 206 which are set out in three symmetrically centralised lines (Ai, A2, and A3) of spaced apart attachment points along the longitudinal length of the flexible composite 600 but where the attachment points 206 of neighbouring lines are offset with respect to each other.

[00106] In another example embodiment of the invention (not shown in the figures) a high-density network of small attachment points 206 could be provided. That is, a grid of closely spaced attachment points 206 (e.g. circular attachment points 0.01m or 0.005m in diameter and spaced apart from neighbouring attachment points 206 by 0.1m or 0.01m) where the attachment points are configured with a relatively weak attachment in peel strength but a stronger attachment when loaded in shear, advantageously allowing users to cut the flexible composite to any desired shape / angle whilst still being able to peel away layer 202 from the fluid barrier layer to form a flap sufficiently large and shaped for welding.

[00107] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other components.

[00108] It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each features disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[00109] All of the features disclosed in this specification may be combined in any combination, expect combinations where at least some of such features are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

[00110] Many of the features described above, particularly of the preferred embodiments, are inventive in their own right and not just as part of an embodiment of the present invention. Independent protection may be sought for these features in addition to or alternative to any invention presently claimed.

Claims

1. A flexible composite comprising:a first layer;a second layer opposing the first layer and separated from the first layer by a space;a fill material located in the space between the first and second layers;a plurality of linking elements within the space which join the first and second layers together; anda third layer attached to the first layer or the second layer at two or more discrete spaced apart attachment points, thereby defining a flap in the third layer between one or more edges of the third layer and the attachment points, the flap for use in joining the flexible composite to another surface.

2. The flexible composite of claim 1, wherein the third layer comprises a heat bondable material thereby making the flap a heat bondable flap for joining the flexible composite to another surface by heat bonding.

3. The flexible composite according to any preceding claim, wherein when the flexible composite is laid on a flat surface the third layer is substantially contiguous with the first or second layer it is attached to.

4. The flexible composite according to any preceding claim, wherein the first layer, the second layer, and the third layer are substantially the same dimensions in terms of length and width.

5. The flexible composite according to one of claims 1 to 3, wherein the third layer extends beyond one or more edges of the first layer and second layer thereby enlarging the size of the flap at said edges of the flexible composite.

6. The flexible composite according to one of claims 1 to 3, wherein the dimensions of the third layer are smaller than the dimensions of the first layer and second layer in terms of length and width and the first layer and second layer extend beyond one or more edges of the third layer.

7. The flexible composite of any preceding claim, wherein the attachment points are arranged along one or more longitudinal and / or transverse axes of the flexible composite.

8. The flexible composite according to any preceding claim, wherein the discrete spaced apart attachment points are arranged in a line along a length of the layer to which the third layer is attached, preferably forming a straight line of spaced apart attachment points.

9. The flexible composite according to one of claims 1 to 7, wherein the discrete spaced apart attachment points are arranged in two or more lines along a length of the layer to which the third layer is attached, preferably forming two or more straight lines of spaced apart attachment points.

10. The flexible composite according to claim 9, wherein the discrete spaced apart attachment points of neighbouring lines are offset with respect to each other.

11. The flexible composite of any preceding claim, wherein the discrete spaced apart attachment points are substantially circular, square, rectangular, rhombic or triangular in shape, preferably the attachment points are substantially circular in shape.

12. The flexible composite of claim 11, wherein if the discrete spaced apart attachment points are square, rectangular, rhombic or triangular in shape then the shapes have radiused corners.

13. The flexible composite according to any preceding claim, wherein the discrete spaced apart attachment points are substantially circular with a diameter from 0.005 - 2m, preferably from 0.05 - 0.5m, and more preferably 0.2 - 0.4m.

14. The flexible composite according to any preceding claim, wherein the spacing between the nearest point of a neighbouring attachment point is from 0.01 - 5m, preferably from 0.2 to Im, and more preferably from 0.2 to 0.5m.

15. The flexible composite according to any preceding claim, wherein the discrete spaced apart attachment points are symmetrically centred along a longitudinal and / or transverse axis of the flexible composite with respect to sides of the flexible composite.

16. The flexible composite according to any preceding claim, wherein the total surface area of the attachment points is 1 to 60% of the surface area of the layer the third layer is attached to, preferably 1.5 to 30%, more preferably 2 to 10%.XJ. The flexible composite according to any preceding claim, wherein the peel strength of the attachment points is configured to be lower than the shear strength of the attachment points.

18. The flexible composite according to claim 17, wherein the peel strength of the attachment points is lower than the shear strength of the attachment points, preferably between 1-25 times lower than the shear strength of the attachment points, and more preferably 1-10 times lower.

19. The flexible composite according to claim 18, wherein the peel strength of the attachment points is from 0.5-20 kN / m, and preferably 0.5-10 kN / m.

20. The flexible composite according to claim 18 or claim 19, wherein the shear strength of the attachment points is less than or equal to the tensile strength of the layer which the third layer is attached to, preferably the shear strength of the attachment points is from 5-40 kN / m.

21. The flexible composite according to any preceding claim, wherein the third layer comprises at least two sub-layers and wherein the sub-layers may be of the same material or different materials.

22. The flexible composite according to any preceding claim, wherein the third layer and the first or second layer it is attached to have substantially the same melting points at least at the attachment points.

23. The flexible composite according to any one of claims 1 to 21, wherein the third layer has a lower melting point than the melting point of the first or second layer it is attached to has at least at the attachment points.

24. The flexible composite of any preceding claim, wherein the third layer forms a continuous membrane which is substantially impervious to liquids.

25. The flexible composite of any preceding claim, wherein the third layer comprises a thermoplastic.

26. The flexible composite of any preceding claim, wherein the third layer comprises a polymeric material, preferably wherein the third layer comprises a low-melt polymer, polyvinyl chloride, polypropylene, a hot melt extrusion, polyethylene, flexible polypropylene, chlorosulphonatedpolyethylene, polyurethane, EPDM rubber, butyl rubber, neoprene®, polyuria coatings, silicone, latex, natural or synthetic rubbers, or mixtures thereof.

27. The flexible composite according to one of claims 1 to 25, wherein the third layer comprises polyethylene and preferably high-density polyethylene, medium density polyethylene, and / or low-density polyethylene such as linear low-density polyethylene.

28. The flexible composite of any preceding claim, wherein the fill material is a powder, a paste or a foam, preferably the fill material is a powder.

29. The flexible composite of any preceding claim, wherein the fill material between the first and second layers is capable of setting to a rigid or semi-rigid solid on the addition of a liquid, gas or radiation.

30. The flexible composite of any preceding claim, wherein fill material comprises cement.

31. The flexible composite according to one of claims 1 to 28, wherein the fill material comprises water swellable materials such as bentonite clay, super absorbent polymer(s), modified acrylic resin(s), oil swelling elastomer(s), or mixtures thereof.

32. The flexible composite of any preceding claim, wherein the fill material comprises a high-density porous fill material such as sand and / or aggregates.

33. The flexible composite according to one of claims 1 to 28, wherein the fill material comprises:a first fill material capable of setting to a rigid or semi-rigid solid on the addition of a liquid, gas or radiation; anda second fill material in the space, comprising: a water swellable material such as bentonite clay, super absorbent polymer(s), modified acrylic resin(s), oil swelling elastomer(s), or mixtures thereof, and / or a high-density porous fill material such as sand and / or aggregates; and whereinthe flexible composite further comprises a separation layer configured to separate the first fill material from the second fill material in the space.

34. The flexible composite of any preceding claim, wherein the first and / or second layers comprise a non-woven fabric, a woven fabric, a knitted fabric and / or an extruded layer, and preferably wherein the first and / or second layers comprises a non-woven fabric.

35. The flexible composite of claim 34, wherein the first and / or second layers comprise a nonwoven fabric, and said non-woven fabric comprises one or more of polypropylene fibres (such as polyethylene terephthalate fibres), polyester fibres, polyvinyl alcohol fibres, nylon fibres, silnylon fibres, vinyl fibres, basalt fibres, carbon fibres, alkaline resistance fibreglass fibres, glass fibres, coated glass fibres, polyvinylchloride (PVC) fibres, aramid fibres, and natural fibres (such as jute, cotton, and viscose fibres), and preferably the non-woven fabric comprises one or more of polypropylene and polyester fibres.

36. The flexible composite of any preceding claim, wherein the first layer is permeable to gases and liquid, but substantially impermeable to the fill material.

37. The flexible composite of any preceding claim, wherein the second layer is substantially impermeable to the fill material.

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