[go: up one dir, main page]

WO2025064783A1 - Ground cover membrane with a plurality of distributed adhered discrete asperity elements and method - Google Patents

Ground cover membrane with a plurality of distributed adhered discrete asperity elements and method Download PDF

Info

Publication number
WO2025064783A1
WO2025064783A1 PCT/US2024/047642 US2024047642W WO2025064783A1 WO 2025064783 A1 WO2025064783 A1 WO 2025064783A1 US 2024047642 W US2024047642 W US 2024047642W WO 2025064783 A1 WO2025064783 A1 WO 2025064783A1
Authority
WO
WIPO (PCT)
Prior art keywords
asperity
discrete
membrane
recited
structural elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2024/047642
Other languages
French (fr)
Inventor
William Delaney Lewis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Watershed Geosynthetics LLC
Original Assignee
Watershed Geosynthetics LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Watershed Geosynthetics LLC filed Critical Watershed Geosynthetics LLC
Publication of WO2025064783A1 publication Critical patent/WO2025064783A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
    • B09B1/00—Dumping solid waste
    • B09B1/004—Covering of dumping sites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/20—Securing of slopes or inclines
    • 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 elongated membranes for dust control surface ground covers. More particularly, the present invention relates to a ground cover having a thin membrane and attached distributed tall asperity elements extending therefrom and method of manufacture of thin membrane having a tall asperity element profile for ground covers.
  • Geomembranes provide impermeable elongated sheets for use in covering surfaces of landfills and other land sites to restrict ingress of water into the covered ground.
  • Geomembranes sheets have an elongated width and lengths with narrow thickness as a sheet member for overlying a surface such as ground.
  • geomembranes are provided as an elongated roll for unrolling at a site to be covered.
  • Geomembranes are manufactured with either a blown film process or a flat die cast extrusion process.
  • the blown film process extrudes melted plastic material through an air ring extrusion die to form a continuous tubular sheet.
  • Cooling air blows past an exterior wall of the tubular sheet.
  • Guide rollers in a tube collapsing frame narrow the tubular sheet and nip rollers flatten the tubular sheet to a flattened film sheet of a desired thickness.
  • a winder receives the continuous flattened film sheet to form a roll of the sheet or membrane.
  • the blown film process produces films in a thickness of less than 10 mils but can produce film with greater thicknesses for example 55 mils, typically in a range of about 20 mils to about 30 mils.
  • the blown film process is limited from adding projecting structure to the membrane, beyond much more than slight undulations or surface texture that may add some frictional resistance capacity for the membrane.
  • the flat die cast extrusion process extrudes melted plastic through a flat die. The extruded sheet passes between chill rollers for cooling and producing a membrane sheet of a desired thickness.
  • Extruded membranes typically have a thickness in a range up to about 120 mils, generally from about 20 mils to about 80 mils, with the thickness affecting the membrane’s overall permeability, strength, weight, roll length, flexibility and cost
  • Flat die extrusion is capable of forming structure, such as stubs or members that project from a surface of the membrane sheet to define an asperity height relative to the membrane.
  • structure height and shape are directly related to the membrane thickness.
  • Thin geomembranes are not sufficient to support tall projecting structures.
  • a thin membrane with a field of tall structures may not meet strength requirements for typical landfill closures and the stresses that are associated with them.
  • the structural feature creating active turbulence involves impingement structures projecting from the upper surface of the geomembrane.
  • the formation of projecting impingement structures requires a thick sheet (for example, generally, an extruded sheet or air-blown sheet having a thickness in excess of 55 mil).
  • Tall structures thus need thick membranes for formation of extending or projecting structures and for support of such structures.
  • Thin membranes that feature lower materials costs may necessarily lack both material quantity and material strength to form and support projecting tall structures having height sufficient to hold an air layer in place for use as a thin membrane ground cover.
  • the present invention comprises a ground cover of an elongated membrane from which a texturing tall profile of a plurality of attached discrete asperity elements extend in distributed spaced-apart relation from an upper surface.
  • ground cover discrete asperity elements attach adhesively adhered to the membrane.
  • the ground cover provides a membrane having a thickness in a range from 10 mil to 80 mil, optionally in a range from 20 mil to 60 mil.
  • the distal extent of the tall profile of the ground cover ranges from 20 mil to 6,000 mil.
  • the discrete asperity structural element attached to the ground cover comprises a geometric body having a shape selected from the group that is spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular.
  • the discrete asperity structural element attached to the ground cover comprises a mesh grid.
  • the present invention comprises a ground cover of an elongated membrane from which a texturing tall profile of a plurality of adhered discrete asperity elements extend in distributed spaced-apart relation from an upper surface and a non-woven batt layer overlying the membrane and grippingly engaged to the asperity elements.
  • the present invention provides a method comprising the steps of forming an elongated sheet of a membrane and of attaching a plurality of discrete asperity elements distributed in spaced- apart relation for extending to a tall profile from a surface of the membrane.
  • the method further comprises forming the membrane with a thickness in a range from 5 mil to 80 mil, optionally in a range from 30 mil to 50 mil.
  • the method further comprises providing the discrete asperity structural elements sized to define a vertically spaced distal extent of the tall profile from 10 mil to 6,000 mil.
  • the method further comprises providing the discrete asperity structural elements as a geometric body having a shape selected from the group that is spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular.
  • the method further comprises distributing the discrete asperity structural elements randomly across the membrane.
  • the method further particularly comprises the step of fusingly adhering each of the plurality of tall profile defining discrete asperity elements to the membrane during a membrane materials cooling phase of manufacture.
  • the method further particularly comprises the step of adhesively adhering the plurality of tall profile defining discrete asperity elements to the membrane during a membrane materials cooling phase of manufacture.
  • the method further comprises the step of overlying the membrane and attached discrete asperity structural elements with a fabric batt, optionally wherein the fabric batt comprises a nonwoven fabric.
  • Fig. 1 illustrates a thin membrane for a ground cover provided with a tall profile defined by a plurality of adhered discrete asperity elements extending from a surface distributed in spacedapart relation.
  • Fig. 2 illustrates a composite ground cover of the thin membrane shown in Fig. 1 further with an overlying non-woven fabric batt layer grippingly engaged to the plurality of discrete asperity elements extending from the thin membrane.
  • Fig. 3 illustrates the composite ground cover shown in Fig. 2 overlying an outdoor ground surface.
  • Fig. 4 illustrates in schematic view an extrusion apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
  • Fig. 5 illustrates in schematic view a blown film apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
  • FIG. 5 A illustrates in schematic view an alternate embodiment of a blown film apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
  • Fig. 6 illustrates in perspective view a first geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 7 illustrates in perspective view a second geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 8 illustrates in perspective view a third geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 9 illustrates in perspective view a fourth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 10 illustrates in perspective view a fifth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 11 illustrates in perspective view a sixth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
  • Fig. 12 illustrates in perspective view a plurality of materials shavings, each as a seventh geometric body, and a plurality of which form the discrete asperity elements extending from the thin membrane.
  • FIGs. 13 A and 13B illustrate in perspective view and cross-sectional elevational view an alternate embodiment of a ground cover in accordance with the present invention.
  • Fig. 14 illustrates an alternate embodiment of a ground cover having crimped netting pieces as the distributed asperity structural elements attached to the membrane.
  • Fig. 1 illustrates an elongated sheet 10 of a thin membrane 12 with a plurality of attached tall profile discrete asperity elements 28, for use singularly, or as a composite, as a ground cover 10 for overlying a surface of ground at a land site.
  • the thin membrane 12 has an elongated longitudinal length 14 for rolling the elongated sheet 10 into a roll for handling, storage and installation purposes and an elongated width 16.
  • the width 16 of the thin membrane 12 is selective based on width capacity of the manufacturing apparatus.
  • the thin membrane is manufactured with a flat die extrader from which the thin member extrudes, for example, up to about 28 feet.
  • the thin membrane 12 has a thickness 18 that is preferably thin, less than a significant minority of the width, for example, 12 mil to 4000 mil, more generally, up to about 500 mil, preferably 20 mil to 80 mil, more preferably 30 mil to 50 mil.
  • Fig. 2 illustrates a composite ground cover 39 comprising the elongated sheet 10 and an overlying non-woven fabric batt layer 40.
  • Portions 42 of foe batt layer 40 seat into foe gaps 38 of foe tall profile of the elongated sheet and portions grippingly engage 44 the edges of the adjacent discrete asperity elements 28 extending from the surface 24 of the thin membrane.
  • the seating and contacting engagements cooperatively hold foe overlying fabric batt layer 40 to foe elongated sheet 10.
  • foe discrete asperity elements 28 adhere 46, or connect, to foe upper surface 24, as discussed below.
  • FIG. 3 illustrates foe ground cover 39 shown in Fig. 2 overlying a surface 50 of ground 52.
  • the lower surface 26 of the thin membrane seats in engaging contact with the ground surface of a large area land site.
  • the ground cover 39 experiences wind flow generally 60 during ground cover use.
  • the wind 60 flowing over the ground cover 39 develops in situ an interior turbulent air flow layer 62 proximate the ground cover 39 and a transition turbulent air flow layer 64 from proximate an upper surface of foe batt layer 40 to a laminar flow layer 66 vertically spaced therefrom.
  • the fibers of the non-woven batt layer 40 and the discrete asperity elements 28 impinge the flow of wind therethrough.
  • the wind becomes turbulent with tumbling, turning, and twisting eddies 70 within the interior of the non-woven batt layer 40 and in the recesses 38 between the discrete asperity elements 28.
  • the turbulence lessens and transitions in the transition layer 64 to the smooth air flow of the laminar flow 66 of the wind spaced vertically from the ground cover 39.
  • Fig. 4 illustrates in schematic view an extrusion apparatus 70 for manufacture of the thin membrane 12 and attachment of the discrete asperity elements 28 for the elongated sheet 10 illustrated in Fig. 1.
  • the extrusion apparatus 70 includes a tubular chamber 74 containing an elongated auger screw 72 for rotation by a motor 76.
  • a supply hopper 78 holds a supply a meltable polymer pellets such as polyethylene.
  • the hopper 78 communicates the pellets to the tubular chamber 74, and rotation of the auger 72 moves the pellets past a plurality of convection heaters 80 to an extrusion die 82. He pellets are melted to a fluidal mass that moves under pressure through the die 82 to extrude the thin membrane 12.
  • the thin membrane 12 optionally passes between conveying upper and lower rollers 84, which lower roller may be scored to define a texture in the lower surface 26 of the thin membrane 12.
  • a guide roller 86 guides the elongated sheet 10 to a roller 88 for rolling.
  • a supply 90 holds a plurality of the discrete asperity elements 28, for example polymer pellets such as polyethylene.
  • the supply 90 is proximate the outlet of the extrusion die 82.
  • the supply 90 communicates 92 the discrete asperity elements onto the moving thin membrane 12.
  • the exiting thin membrane 12 is cooling from the molten extrusion temperature in the die 12 yet proximate the die 82, surprisingly remains fluidly tacky and particularly the upper surface 24.
  • Hie asperity elements 28 falling from the supply 90 fiisingly stick and adhere with respective adhering connections 46 to the cooling but semi-fluidal upper surface 24 of the thin membrane to form the membrane 12 with attached asperity defining elements 28.
  • a heater 94 pre-heats the asperity elements 28 communicated from the supply onto the upper surface 24 of the thin membrane 12.
  • the heater 94 operates to warm, soften, or partially melt the discrete asperity elements 28 sufficiently for fiisingly adhering to the sheet, so that the temperature of the cooling thin membrane 12 and the asperity elements are consistently the same within an appropriate range.
  • the asperity elements 28 and the thin membrane 12 fiisingly adhere together to form the elongated sheet 10, with the asperity elements being dropped into contact with the moving thin membrane.
  • Some asperity elements 28 however may not fusingly adhere to the upper surface 24 and drop or fall away to an underlying collection tray (not illustrated) for collection and re-loading to the supply 90.
  • the vertical spacing of the discharge from the supply 90 relative to the membrane 12 may be adjusted to accommodate the cooling temperature of the membrane and/or the force at which the asperity elements 28 impact the membrane for attaching the asperity elements fusingly or adhesively to the membrane.
  • FIG. 5 illustrates in schematic view a blown film apparatus 100 as an alternate embodiment for manufacture of a thin membrane 102, such as for use as a ground cover.
  • a supply 104 of plastic pellets communicate into an extruder 106 and are heated to a molten fluid.
  • An auger carries the molten plastic to a ring extrusion die 108 that also communicates with a supply of blown air 110.
  • the plastic material exits the extrusion die 108 forming a tubular sheet 116. Air blown into the moving tubular sheet 116 moves the sheet outwardly to a predetermined radius.
  • a cooling tower generally 118 receives the blown tubular thin sheet membrane from the blown-air tube formation die 108.
  • the tube collapsing fame 120 includes a plurality of spaced rollers 122 to draw the tubular sheet together.
  • Nip rollers 124 flatten the tube to a flat sheet.
  • a supply hopper 130 mounts proximate an exit portion of the nip rollers 124.
  • the supply hopper 130 contains a flowable plurality of the discrete asperity elements 28. (In the illustrated embodiment, the discrete asperity elements 28 are spherical bodies).
  • the discrete asperity elements 28 drop 136 onto the cooling flattened sheet 102.
  • the discrete asperity elements 28 adheringly affix to the surface of the flattened sheet 102.
  • a heater 94 warms, softens, or partially melts the asperity elements 28 for fusingly attaching to the sheet.
  • the continuous moving sheet 102 passes edge trim cutters 138 and a winder 140 winds the sheet membrane 102 with the affixed asperity elements 28 into a roll 144.
  • Asperity elements 28 that do not adhere fall to a collection tray (not illustrated) for re-inserting into the supply hopper 130.
  • a jetting air duct 150 communicates air jets towards the flattened sheet.
  • the air entrains some of the discrete asperity elements 28 flowing from the supply hopper 130.
  • the discrete asperity elements 28 carried by the air jets impinge the cooling but still fluidal surface of the blow-formed thin membrane.
  • the impinging elements fusingly adhere to the cooling but adherable thin membrane 102.
  • Asperity elements 28 that do not adhere fall to a collection tray (not illustrated) for re-inserting into the supply hopper 130.
  • an adhesive may be applied 93 to the surface of the membrane, or to the asperity elements, for adheringly attaching elements formed of a non-fusible material.
  • Fig. 5A illustrates in schematic view an alternate embodiment of a blown film apparatus 100a for manufacture of a thin membrane 102, such as for use as a ground cover.
  • a supply hopper 130a mounts in spaced relation around the forming column from the extrusion die 108.
  • the supply hopper 130a may be a torus, with a discharge 131 in a bottom side.
  • a ring 132 spaced below the discharge 131 includes an angled pitch plate 133.
  • the discrete asperity elements 28 fall from the discharge 131 of the supply hopper 130a and bounce off of the angled pitch plate 133 against the surface of the blown tubular thin sheet membrane flowing from the blown-air tube formation die 108.
  • a collection tray not illustrated
  • An alternate embodiment may use an adhesive supply and nozzle for spraying an adhesive onto the formed cooling membrane for attaching the asperity elements.
  • the membrane and the asperity elements form from the same materials, such as LLPE or HDPE, or of materials that readily fuse or attach adhesively together.
  • the asperity elements 28 are discrete articles supplied from the supply hopper for engaging the thin membrane during a materials cooling phase of manufacture.
  • the asperity elements 28 are of regular or irregular shapes, for example, spherical, ovoid, cube, multi- polygonal, material shavings, or irregular shapes such as jagged or multiple facets.
  • the rollability of the sheet may be a limiting factor based on the size and the distribution of the asperity elements 28 on the membrane. For example, a sheet with attached larger asperity element (providing a six inch height) may be more difficult to roll during manufacture and unroll during site installation while a membrane with attached shorter asperity elements may roll and unroll more easily.
  • Fig. 6 illustrates in perspective view a first geometric body 160 having a spherical shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet
  • a lower portion of the spherical shape asperity elements 28 may catch and hold an overlying fiber sheet, for example, strands of a netting or mesh grid that overlies the membrane on a land site surface.
  • Fig. 7 illustrates in perspective view a second geometric body 162 having an oblong regular shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
  • Fig. 8 illustrates in perspective view a third geometric body 164 having a pyramidal shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
  • Fig. 9 illustrates in perspective view a fourth geometric body 166 having a diamond shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
  • Fig. 10 illustrates in perspective view a fifth geometric body 168 having a jacks shape defined by a plurality of arms 170 extending from a central core 172, a plurality of which form the discrete asperity elements 28 for adhering to extending from the thin membrane sheet.
  • Fig. 11 illustrates in perspective view a sixth geometric body 176 having an irregular geometric shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
  • Fig. 12 illustrates in perspective view a plurality of material shavings 178, each as a seventh geometric body and a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
  • the material shavings may be planar or curled.
  • Figs. 13 A and 13B illustrate in perspective view and cross-sectional elevational view an alternate embodiment of a ground cover 200 in accordance with the present invention.
  • the ground cover 200 comprises a thin membrane 202 as a carrying substrate with an attached three- dimensional reinforcement mat 204 (or alternative, a plurality of spaced-apart pieces of such).
  • the mat 204 (or mat pieces) distributed onto the membrane 202 as asperity structural elements 28 are made of continuous monofilaments 206 fused at intersections 207, whereby a majority (for example, up to about 95%) of the structure is open for defining air flow pathways therethrough.
  • the mat 204 defines a flexible vertically extended asperity-defining matrix generally 210 providing open air flow pathways illustrated by arrow 212 through the filaments 206 that interconnect by the fused interconnections of the filaments for a defined mat thickness 214.
  • Mats useful with foe present embodiment include ENKAMAT three-dimensional reinforcement mats available from Freudenberg Performance Materials (www.enkasoutions.com).
  • the netting pieces attach adhesively.
  • Fig. 14 illustrates an alternate embodiment of a ground cover 220 having crimped netting pieces 222 as the distributed asperity structural elements 28 attached to the thin membrane 224.
  • Crimped netting comprises interwoven and crimped elongated members 226, 228 to form a mesh grid or netting 229.
  • Crimped netting is available with porosity from about 50% to 95% based on aperture opening 230, wire or elongated member center-to-center spacing of the weave, and wire or fiber diameters.
  • Contacting portions 232 of the crimped netting seat into the membrane 224, or if a meltable plastic material, fiisingly connect, to form the ground cover 220.
  • the netting pieces attach adhesively.
  • the distributed asperity structural elements accordingly may alternatively comprise pieces of the three-dimensional reinforcement mats, crimped netting, or geocomposite pieces having three dimensional shapes featuring both porosity and asperity characteristics by which is defined foe air flow pathways in combination with vertically spaced asperity height relative to the membrane to which foe elements attach.
  • the pieces may be discrete or mechanically interconnected by engaged ends of adjacent pieces. The pieces attach in any orientation, for example, randomly oriented or regular spaced.
  • the pieces may be wholly or partially connected to foe membrane.
  • a partially connected piece may have an extending free portion that flaps in foe wind flow over and through foe asperity elements, which creates or adds additional disturbance to the wind flow.
  • Embodiments include small pieces (2 inch by 2 inch, with a thickness for defining a vertical asperity height) or elongated pieces (for example, 2 inch wide by 12 inch long and a selected asperity height).
  • the asperity elements 28 preferably are flowable.
  • the asperity elements are flowable from the supply hopper for application to the thin membrane sheet during manufacture.
  • the asperity elements 28 range in size from 10 mil to 6 inches, with the larger asperity elements generally having a lower distribution over the sheet.
  • the asperity elements extend outwardly from the surface of the ground cover to a distal extent, for example, 10 mil to 6 inches (such as subject to rollability and distribution factors), more preferably 10 mil to 500 mil, or 20 mil to 80 mil.
  • the asperity elements are distributed across the surface of the membrane for use as ground cover sheet, for example, in fixed spaced-relation as rows and columns, offset rows and columns (that is, an adjacent row positions the asperity element in alignment with a gap between adjacent asperity elements in the adjacent row), or randomly. Smaller asperity elements may have a higher distribution density while larger asperity elements would have a smaller distribution density.
  • the distribution density of the asperity elements ranges from about 5 asperity elements per square foot to about 10,000 asperity elements per square foot, more preferably from 10 asperity elements per square foot to 8000 asperity elements per square foot, and more particularly, from 15 asperity elements per square foot to 3000 asperity elements per square foot.
  • a geometric body providing a 10 mil distal height may have a density of 9200 per square foot while a geometric body providing a 50 mil distal height may have density that is significantly less.
  • a ground cover of a thin membrane with increased wind resistance is provided.
  • a plurality of asperity elements of like material and even temperature (or range) are directed onto a thin membrane, during cooling and prior to final cooling, for readily adheringly to an upper surface of the thin membrane to provide an elongated sheet featuring a tall structure for ground cover usage.
  • the supply hopper for the discrete asperity elements may optionally include the heater elements (heat source and temperature sensor), for providing a temperature control for example proximate the roller in a flat die cast extrusion process.
  • the hopper holds small, shaped PE particles that disperse onto the thin membrane prior to final cooling.
  • the hopper disperses the PE shapes (particles) at a predetermined rate and heat across and onto the thin membrane before the thin membrane cools.
  • the particles adhere in a random distribution of fused, tall structures for use of the thin membrane as a wind-protected ground cover.
  • the asperity elements adhesively attach to the membrane.
  • the formed thin geomembrane with attached asperity elements 28 readily installs over large area ground surfaces aS a ground cover, as shown in Fig. 3.
  • the lower surface 26 of the thin membrane seats in engaging contact with the ground surface of a large area land site.
  • the tall structure asperity elements 28 and the fibers of the non-woven batt layer 40 form impingements to the wind 60 flowing over the ground cover 39. This develops in situ the interior turbulent air flow layer 62 proximate the ground cover 39.
  • the wind becomes turbulent with tumbling, turning, and twisting eddies 70 within the interior of the non-woven batt layer 40 and in the recesses 38 between the discrete asperity elements 28.
  • the turbulent air flow layer resists wind uplift forces of the laminar flow on the geomembrane, separated by the transition turbulent air flow layer 64 from proximate an upper surface of the batt layer 40 to the vertically spaced laminar flow layer 66. Upwardly from the air flow boundary 44 the turbulence lessens and transitions in the transition layer 64 to the smooth air flow of the laminar flow 66 of the wind spaced vertically from the ground cover 39.
  • the mat 204 operates to overlie a surface such as a land site ground surface.
  • the flexible vertically extended asperity-defining matrix generally 210 provides open air flow pathways illustrated by arrow 212 through the filaments 206 that interconnect by the fused interconnections of the filaments for a defined mat thickness 214.
  • the tall structure asperity matrix form impingements to the wind flowing over the ground cover. This develops in situ the interior turbulent air flow layer proximate the ground cover. As a result, the wind becomes turbulent with tumbling, turning, and twisting eddies within the interior of the matrix.
  • the turbulent air flow layer resists wind uplift forces of the laminar flow on the ground cover, separated by the transition turbulent air flow layer from proximate an upper surface of the membrane to the vertically spaced laminar flow layer. Upwardly from the air flow boundary the turbulence lessens and transitions in the transition layer to the smooth air flow of the laminar flow of the wind spaced vertically from the ground cover.
  • the mesh 229 of the ground cover 220 overlying a surface provides a tall structure asperity extent with the openings in the mesh allowing turbulent air flow over the ground cover.
  • the turbulent air flow layer resists wind uplift forces of the laminar flow on the ground cover, separated by the transition turbulent air flow layer from proximate an upper surface of the of the membrane to the vertically spaced laminar flow layer. Upwardly from the air flow boundary the turbulence lessens and transitions in the transition layer to the smooth air flow of the laminar flow of the wind spaced vertically from the ground cover.
  • Embodiments of the present invention preferably have a thin membrane with a thickness of up to about 80 mil, more preferably in a range of 30 mil to 50 mil and a plurality of distributed asperity structural elements defining a vertical distal asperity height relative to the membrane up to about 1,500 mil, more preferably of 10 mil to 1,000 mil, more preferably 20 mil to 400 mil. These relative dimensional features are heretofore unavailable in membrane structures but provided by the present invention.
  • the membrane thereby is a carrier for attached positioning of the asperity structural elements in lateral spaced distributed relation extending vertically from the membrane to define a distal extent within a wind flow stream over a surface covered by the ground cover membrane but the membrane surprisingly does not need the increased foundational structure necessary for the prior art formation of the vertical asperity structural elements and thereby the present invention materially and surprisingly reduces material costs significantly.
  • the foregoing discloses a method of making a ground cover, comprising the steps of: (a) forming an elongated thermoplastic membrane; and (b) attaching a plurality of discrete asperity structural elements to define a tall vertical profile.
  • the asperity elements fusingly attach or adhesively attach.
  • the membrane forms with a thickness in a range up to about 65 mil.
  • the membrane forms with a thickness a thickness in a range of between about 20 mil and about 80 mil.
  • the attached discrete asperity structural elements define a vertically spaced distal extent of the tall profile up to about 6,000 mil, alternatively, up to 1,500 mil, and alternatively the tall profile ranges between 50 mil and 1,500 mil.
  • the vertically spaced distal extent of the tall profile has a height that exceeds the thickness of the membrane.
  • the discrete asperity structural elements distribute randomly.
  • the discrete asperity structural elements distribute in ordered rows.
  • the discrete asperity structural elements distribute with a density in a range of 5 discrete asperity structural elements to 10,000 discrete asperity structural elements per square foot depending on asperity element size.
  • the method further comprises the step of adding a fabric batt overlying the discrete asperity structural elements.
  • a ground cover comprising an elongated thermoplastic membrane having a thickness and a plurality of discrete asperity structural elements attached in spaced-apart relation to an upper surface of the membrane to define a tall profile, said asperity structural elements defining a distal extent vertically spaced from the upper surface.
  • the thickness of the membrane is in a range up to about 80 mil and the distal extent of the tall profile in a range of between 10 mil to 6,000 mil.
  • the height of the distal extent in some embodiments exceeds the thickness of the membrane.
  • the ground cover further comprises a fabric batt overlying the discrete asperity structural elements.
  • the asperity elements comprise a crimped mesh for attaching to the membrane.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Hydrology & Water Resources (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

A ground cover (10) comprising an elongated thermoplastic membrane (12) having a thickness (18) and a plurality of discrete asperity structural elements (28) attached (fuisingly or adhesively) in spaced-apart relation to an upper surface of the membrane to define a tall profile with a distal extent of the tall profile vertically spaced from the upper surface for improved resistance to wind shear forces. The ground cover made by a method comprising the steps of (a) forming an elongated thermoplastic membrane; and (b) attaching (fusingly of adhesively) a plurality of discrete asperity structural elements to define a tall vertical profile for improved resistance to wind shear forces.

Description

GROUND COVER MEMBRANE WITH A PLURALITY OF DISTRIBUTED
ADHERED DISCRETE ASPERITY ELEMENTS AND METHOD
Technical Field
[0001] The present invention relates to elongated membranes for dust control surface ground covers. More particularly, the present invention relates to a ground cover having a thin membrane and attached distributed tall asperity elements extending therefrom and method of manufacture of thin membrane having a tall asperity element profile for ground covers.
Background Of The Invention
[0002] Geomembranes provide impermeable elongated sheets for use in covering surfaces of landfills and other land sites to restrict ingress of water into the covered ground. Geomembranes sheets have an elongated width and lengths with narrow thickness as a sheet member for overlying a surface such as ground. Typically, geomembranes are provided as an elongated roll for unrolling at a site to be covered.
[0003] Geomembranes are manufactured with either a blown film process or a flat die cast extrusion process. The blown film process extrudes melted plastic material through an air ring extrusion die to form a continuous tubular sheet. Air flows through the ring and expands the film to a tubular sheet with a desired radius dimension. Cooling air blows past an exterior wall of the tubular sheet. Guide rollers in a tube collapsing frame narrow the tubular sheet and nip rollers flatten the tubular sheet to a flattened film sheet of a desired thickness. A winder receives the continuous flattened film sheet to form a roll of the sheet or membrane. Generally, the blown film process produces films in a thickness of less than 10 mils but can produce film with greater thicknesses for example 55 mils, typically in a range of about 20 mils to about 30 mils. The blown film process is limited from adding projecting structure to the membrane, beyond much more than slight undulations or surface texture that may add some frictional resistance capacity for the membrane. [0004] The flat die cast extrusion process extrudes melted plastic through a flat die. The extruded sheet passes between chill rollers for cooling and producing a membrane sheet of a desired thickness. Extruded membranes typically have a thickness in a range up to about 120 mils, generally from about 20 mils to about 80 mils, with the thickness affecting the membrane’s overall permeability, strength, weight, roll length, flexibility and cost Flat die extrusion is capable of forming structure, such as stubs or members that project from a surface of the membrane sheet to define an asperity height relative to the membrane. However, the structure height and shape are directly related to the membrane thickness. Thin geomembranes are not sufficient to support tall projecting structures. Also, a thin membrane with a field of tall structures may not meet strength requirements for typical landfill closures and the stresses that are associated with them.
[0005] Nevertheless, the landfill industry is beginning to utilize exposed membranes for long term interim cover. Wind forces can have an adverse impact on exposed geomembranes such as wind uplift and displacement. Displacement creates wrinkles in the ground cover that increases wear and degradation of the ground cover. Wrinkles may lead to voids being formed in the underlying ground surface. However, a structural feature of a geomembrane that creates active turbulence in wind flow proximate the geomembrane and separating laminar flow may protect the underlying geomembrane from the wind loading forces that create uplift and displacement. Such ground cover thus does not require a high shear strength for the geomembrane and its structure as with typical structured membrane applications. The structural feature creating active turbulence involves impingement structures projecting from the upper surface of the geomembrane. The formation of projecting impingement structures however requires a thick sheet (for example, generally, an extruded sheet or air-blown sheet having a thickness in excess of 55 mil). Tall structures thus need thick membranes for formation of extending or projecting structures and for support of such structures. Thin membranes that feature lower materials costs may necessarily lack both material quantity and material strength to form and support projecting tall structures having height sufficient to hold an air layer in place for use as a thin membrane ground cover.
[0006] Accordingly, there is a need in the art for an improved ground cover having a thin membrane but providing a tall profile of distributed asperity structural elements and a method of manufacture. It is to such that the present invention is directed. Brief Summary Of The Invention
[0007] The present invention meets a need in the art by providing both a method for manufacture of an improved membrane for a ground cover and an improved membrane ground cover for overlying a ground surface. The improved membrane features a plurality of projecting distributed tall structure asperity elements attached thereto during manufacture of the membrane. The improved ground cover comprises an elongated thermoplastic membrane having a thickness and a plurality of discrete asperity elements attached in spaced-apart relation extending from a surface of the membrane defining a distal extent of a tall profile spaced from the upper surface of the membrane.
[0008] In another aspect, the present invention comprises a ground cover of an elongated membrane from which a texturing tall profile of a plurality of attached discrete asperity elements extend in distributed spaced-apart relation from an upper surface.
[0009] More particularly, the ground cover discrete asperity elements attach fusingly adhered to the membrane.
[00101 More particularly, the ground cover discrete asperity elements attach adhesively adhered to the membrane.
[0011] More particularly, the ground cover provides a membrane having a thickness in a range from 10 mil to 80 mil, optionally in a range from 20 mil to 60 mil.
[0012] More particularly, the distal extent of the tall profile of the ground cover ranges from 20 mil to 6,000 mil.
[0013] More particularly, the discrete asperity structural elements are distributed randomly across the membrane.
[0014] More particularly, the discrete asperity structural element attached to the ground cover comprises a geometric body having a shape selected from the group that is spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular. [0015] More particularly, the discrete asperity structural element attached to the ground cover comprises a mesh grid.
[0016] In another aspect, the present invention comprises a ground cover of an elongated membrane from which a texturing tall profile of a plurality of adhered discrete asperity elements extend in distributed spaced-apart relation from an upper surface and a non-woven batt layer overlying the membrane and grippingly engaged to the asperity elements.
[0017] The present invention provides a method comprising the steps of forming an elongated sheet of a membrane and of attaching a plurality of discrete asperity elements distributed in spaced- apart relation for extending to a tall profile from a surface of the membrane.
[0018] More particularly, the method further comprises forming the membrane with a thickness in a range from 5 mil to 80 mil, optionally in a range from 30 mil to 50 mil.
[0019] More particularly, the method further comprises providing the discrete asperity structural elements sized to define a vertically spaced distal extent of the tall profile from 10 mil to 6,000 mil.
[0020] More particularly, the method further comprises providing the discrete asperity structural elements as a geometric body having a shape selected from the group that is spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular.
[0021] More particularly, the method further comprises distributing the discrete asperity structural elements randomly across the membrane.
[0022] In another aspect, the method further particularly comprises the step of fusingly adhering each of the plurality of tall profile defining discrete asperity elements to the membrane during a membrane materials cooling phase of manufacture.
[0023] In another aspect, the method further particularly comprises the step of adhesively adhering the plurality of tall profile defining discrete asperity elements to the membrane during a membrane materials cooling phase of manufacture. [0024] In another aspect, the method further comprises the step of overlying the membrane and attached discrete asperity structural elements with a fabric batt, optionally wherein the fabric batt comprises a nonwoven fabric.
[0025] Objects, advantages, and features of the present invention will be readily apparat to one of ordinary skill in the art upon a reading of the following detailed description in reference to the drawings.
Brief Description Of The Drawings
[0026] Fig. 1 illustrates a thin membrane for a ground cover provided with a tall profile defined by a plurality of adhered discrete asperity elements extending from a surface distributed in spacedapart relation.
[0027] Fig. 2 illustrates a composite ground cover of the thin membrane shown in Fig. 1 further with an overlying non-woven fabric batt layer grippingly engaged to the plurality of discrete asperity elements extending from the thin membrane.
[0028] Fig. 3 illustrates the composite ground cover shown in Fig. 2 overlying an outdoor ground surface.
[0029] Fig. 4 illustrates in schematic view an extrusion apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
[0030] Fig. 5 illustrates in schematic view a blown film apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
[0031] Fig. 5 A illustrates in schematic view an alternate embodiment of a blown film apparatus for manufacture of the thin membrane illustrated in Fig. 1 for the ground cover.
[0032] Fig. 6 illustrates in perspective view a first geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
[0033] Fig. 7 illustrates in perspective view a second geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane. [0034] Fig. 8 illustrates in perspective view a third geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
[0035] Fig. 9 illustrates in perspective view a fourth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
[0036] Fig. 10 illustrates in perspective view a fifth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
[0037] Fig. 11 illustrates in perspective view a sixth geometric body, a plurality of which form the discrete asperity elements extending from the thin membrane.
[0038] Fig. 12 illustrates in perspective view a plurality of materials shavings, each as a seventh geometric body, and a plurality of which form the discrete asperity elements extending from the thin membrane.
[0039] Figs. 13 A and 13B illustrate in perspective view and cross-sectional elevational view an alternate embodiment of a ground cover in accordance with the present invention.
[0040] Fig. 14 illustrates an alternate embodiment of a ground cover having crimped netting pieces as the distributed asperity structural elements attached to the membrane.
Detailed Description of Illustrative Embodiments
[0041] With reference to the drawings in which like parts have like identifiers, Fig. 1 illustrates an elongated sheet 10 of a thin membrane 12 with a plurality of attached tall profile discrete asperity elements 28, for use singularly, or as a composite, as a ground cover 10 for overlying a surface of ground at a land site. The thin membrane 12 has an elongated longitudinal length 14 for rolling the elongated sheet 10 into a roll for handling, storage and installation purposes and an elongated width 16. The width 16 of the thin membrane 12 is selective based on width capacity of the manufacturing apparatus. In the illustrative embodiment, the thin membrane is manufactured with a flat die extrader from which the thin member extrudes, for example, up to about 28 feet. The thin membrane 12 has a thickness 18 that is preferably thin, less than a significant minority of the width, for example, 12 mil to 4000 mil, more generally, up to about 500 mil, preferably 20 mil to 80 mil, more preferably 30 mil to 50 mil.
[0042] The membrane 12 includes opposing upper and lower surfaces 24, 26. In the illustrated embodiment, a plurality of adhered discrete asperity elements 28 extend from the upper surface 24 as a tall profile to a respective distal asperity extent 29 in spaced-apart distributed relation, to form the elongated sheet. The asperity elements 28 may be disposed in uniformly spaced or ordered rows and columns, or may be distributed randomly. The asperity elements 29 fusingly adhere, or in an alternate embodiment, adhesively adhere to the membrane.
[0043] The distal extents 29 of the discrete asperity elements 28 may be unequal in respective extended height 30 relative to foe surface of foe membrane to define an undulating outer boundary 34 spaced from foe surface 24. Alternatively, foe discrete asperity elements 28 may have a regular shape and be placed particularly for defining a uniform outer boundary. The spaced discrete asperity elements 28 define intermediate gaps or open recesses 38 between adjacent ones of foe discrete asperity elements 28 and foe upper surface 24.
[0044] The lower surface 26 may be textured, such as a pressing roller having a scored pattern that embosses foe pattern as a texturization.
[0045] Fig. 2 illustrates a composite ground cover 39 comprising the elongated sheet 10 and an overlying non-woven fabric batt layer 40. Portions 42 of foe batt layer 40 seat into foe gaps 38 of foe tall profile of the elongated sheet and portions grippingly engage 44 the edges of the adjacent discrete asperity elements 28 extending from the surface 24 of the thin membrane. The seating and contacting engagements cooperatively hold foe overlying fabric batt layer 40 to foe elongated sheet 10. As shown in Fig. 2, foe discrete asperity elements 28 adhere 46, or connect, to foe upper surface 24, as discussed below.
[0046] Fig. 3 illustrates foe ground cover 39 shown in Fig. 2 overlying a surface 50 of ground 52. The lower surface 26 of the thin membrane seats in engaging contact with the ground surface of a large area land site. The ground cover 39 experiences wind flow generally 60 during ground cover use. The wind 60 flowing over the ground cover 39 develops in situ an interior turbulent air flow layer 62 proximate the ground cover 39 and a transition turbulent air flow layer 64 from proximate an upper surface of foe batt layer 40 to a laminar flow layer 66 vertically spaced therefrom. The fibers of the non-woven batt layer 40 and the discrete asperity elements 28 impinge the flow of wind therethrough. As a result, the wind becomes turbulent with tumbling, turning, and twisting eddies 70 within the interior of the non-woven batt layer 40 and in the recesses 38 between the discrete asperity elements 28. Upwardly from the air flow boundary 44 the turbulence lessens and transitions in the transition layer 64 to the smooth air flow of the laminar flow 66 of the wind spaced vertically from the ground cover 39.
[0047] Fig. 4 illustrates in schematic view an extrusion apparatus 70 for manufacture of the thin membrane 12 and attachment of the discrete asperity elements 28 for the elongated sheet 10 illustrated in Fig. 1. The extrusion apparatus 70 includes a tubular chamber 74 containing an elongated auger screw 72 for rotation by a motor 76. A supply hopper 78 holds a supply a meltable polymer pellets such as polyethylene. The hopper 78 communicates the pellets to the tubular chamber 74, and rotation of the auger 72 moves the pellets past a plurality of convection heaters 80 to an extrusion die 82. He pellets are melted to a fluidal mass that moves under pressure through the die 82 to extrude the thin membrane 12. The thin membrane 12 optionally passes between conveying upper and lower rollers 84, which lower roller may be scored to define a texture in the lower surface 26 of the thin membrane 12. A guide roller 86 guides the elongated sheet 10 to a roller 88 for rolling.
[0048] A supply 90 holds a plurality of the discrete asperity elements 28, for example polymer pellets such as polyethylene. The supply 90 is proximate the outlet of the extrusion die 82. The supply 90 communicates 92 the discrete asperity elements onto the moving thin membrane 12. The exiting thin membrane 12 is cooling from the molten extrusion temperature in the die 12 yet proximate the die 82, surprisingly remains fluidly tacky and particularly the upper surface 24. Hie asperity elements 28 falling from the supply 90 fiisingly stick and adhere with respective adhering connections 46 to the cooling but semi-fluidal upper surface 24 of the thin membrane to form the membrane 12 with attached asperity defining elements 28. In an alternate embodiment, a heater 94 pre-heats the asperity elements 28 communicated from the supply onto the upper surface 24 of the thin membrane 12. The heater 94 operates to warm, soften, or partially melt the discrete asperity elements 28 sufficiently for fiisingly adhering to the sheet, so that the temperature of the cooling thin membrane 12 and the asperity elements are consistently the same within an appropriate range. The asperity elements 28 and the thin membrane 12 fiisingly adhere together to form the elongated sheet 10, with the asperity elements being dropped into contact with the moving thin membrane. Some asperity elements 28 however may not fusingly adhere to the upper surface 24 and drop or fall away to an underlying collection tray (not illustrated) for collection and re-loading to the supply 90.
[0049] The vertical spacing of the discharge from the supply 90 relative to the membrane 12 may be adjusted to accommodate the cooling temperature of the membrane and/or the force at which the asperity elements 28 impact the membrane for attaching the asperity elements fusingly or adhesively to the membrane.
[0050] Fig. 5 illustrates in schematic view a blown film apparatus 100 as an alternate embodiment for manufacture of a thin membrane 102, such as for use as a ground cover. A supply 104 of plastic pellets communicate into an extruder 106 and are heated to a molten fluid. An auger carries the molten plastic to a ring extrusion die 108 that also communicates with a supply of blown air 110. The plastic material exits the extrusion die 108 forming a tubular sheet 116. Air blown into the moving tubular sheet 116 moves the sheet outwardly to a predetermined radius. In this embodiment, a cooling tower generally 118 receives the blown tubular thin sheet membrane from the blown-air tube formation die 108. Cooling air flows past the outer surface of the tubular sheet as the tubular sheet moves vertically to a tube collapsing fame 120. The tube collapsing fame 120 includes a plurality of spaced rollers 122 to draw the tubular sheet together. Nip rollers 124 flatten the tube to a flat sheet. A supply hopper 130 mounts proximate an exit portion of the nip rollers 124. The supply hopper 130 contains a flowable plurality of the discrete asperity elements 28. (In the illustrated embodiment, the discrete asperity elements 28 are spherical bodies).
[0051] In a first embodiment, the discrete asperity elements 28 drop 136 onto the cooling flattened sheet 102. The discrete asperity elements 28 adheringly affix to the surface of the flattened sheet 102. (In an alternate embodiment, a heater 94 warms, softens, or partially melts the asperity elements 28 for fusingly attaching to the sheet.) The continuous moving sheet 102 passes edge trim cutters 138 and a winder 140 winds the sheet membrane 102 with the affixed asperity elements 28 into a roll 144. Asperity elements 28 that do not adhere fall to a collection tray (not illustrated) for re-inserting into the supply hopper 130. [0052] In a second embodiment, a jetting air duct 150 communicates air jets towards the flattened sheet. The air entrains some of the discrete asperity elements 28 flowing from the supply hopper 130. (An alternate embodiment may use the heater 94 to soften, warm, or partially melt the asperity elements.) The discrete asperity elements 28 carried by the air jets impinge the cooling but still fluidal surface of the blow-formed thin membrane. The impinging elements fusingly adhere to the cooling but adherable thin membrane 102. Asperity elements 28 that do not adhere fall to a collection tray (not illustrated) for re-inserting into the supply hopper 130.
[0053] In an alternate embodiment, an adhesive may be applied 93 to the surface of the membrane, or to the asperity elements, for adheringly attaching elements formed of a non-fusible material.
[0054] Fig. 5A illustrates in schematic view an alternate embodiment of a blown film apparatus 100a for manufacture of a thin membrane 102, such as for use as a ground cover. In this embodiment, a supply hopper 130a mounts in spaced relation around the forming column from the extrusion die 108. The supply hopper 130a may be a torus, with a discharge 131 in a bottom side. A ring 132 spaced below the discharge 131 includes an angled pitch plate 133. The discrete asperity elements 28 fall from the discharge 131 of the supply hopper 130a and bounce off of the angled pitch plate 133 against the surface of the blown tubular thin sheet membrane flowing from the blown-air tube formation die 108. Asperity elements 28 that do not attach fell to a collection tray (not illustrated) for re-inserting into the supply hopper 130a. (An alternate embodiment may use an adhesive supply and nozzle for spraying an adhesive onto the formed cooling membrane for attaching the asperity elements.)
[0055] Preferably the membrane and the asperity elements form from the same materials, such as LLPE or HDPE, or of materials that readily fuse or attach adhesively together.
[0056] The asperity elements 28 are discrete articles supplied from the supply hopper for engaging the thin membrane during a materials cooling phase of manufacture. The asperity elements 28 are of regular or irregular shapes, for example, spherical, ovoid, cube, multi- polygonal, material shavings, or irregular shapes such as jagged or multiple facets. The rollability of the sheet may be a limiting factor based on the size and the distribution of the asperity elements 28 on the membrane. For example, a sheet with attached larger asperity element (providing a six inch height) may be more difficult to roll during manufacture and unroll during site installation while a membrane with attached shorter asperity elements may roll and unroll more easily.
[0057] Fig. 6 illustrates in perspective view a first geometric body 160 having a spherical shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet A lower portion of the spherical shape asperity elements 28 may catch and hold an overlying fiber sheet, for example, strands of a netting or mesh grid that overlies the membrane on a land site surface.
[0058] Fig. 7 illustrates in perspective view a second geometric body 162 having an oblong regular shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
[0059] Fig. 8 illustrates in perspective view a third geometric body 164 having a pyramidal shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
[0060] Fig. 9 illustrates in perspective view a fourth geometric body 166 having a diamond shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
[0061] Fig. 10 illustrates in perspective view a fifth geometric body 168 having a jacks shape defined by a plurality of arms 170 extending from a central core 172, a plurality of which form the discrete asperity elements 28 for adhering to extending from the thin membrane sheet.
[0062] Fig. 11 illustrates in perspective view a sixth geometric body 176 having an irregular geometric shape, a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet.
[0063] Fig. 12 illustrates in perspective view a plurality of material shavings 178, each as a seventh geometric body and a plurality of which form the discrete asperity elements 28 for adhering to and extending from the thin membrane sheet. The material shavings may be planar or curled.
[0064] Figs. 13 A and 13B illustrate in perspective view and cross-sectional elevational view an alternate embodiment of a ground cover 200 in accordance with the present invention. The ground cover 200 comprises a thin membrane 202 as a carrying substrate with an attached three- dimensional reinforcement mat 204 (or alternative, a plurality of spaced-apart pieces of such). The mat 204 (or mat pieces) distributed onto the membrane 202 as asperity structural elements 28 are made of continuous monofilaments 206 fused at intersections 207, whereby a majority (for example, up to about 95%) of the structure is open for defining air flow pathways therethrough. During manufacturing placement of the mat 204 onto the thin membrane 202, a plurality of portions 208 of the mat contact and fiisingly connect to the upper surface of the membrane. The mat 204 defines a flexible vertically extended asperity-defining matrix generally 210 providing open air flow pathways illustrated by arrow 212 through the filaments 206 that interconnect by the fused interconnections of the filaments for a defined mat thickness 214. Mats useful with foe present embodiment include ENKAMAT three-dimensional reinforcement mats available from Freudenberg Performance Materials (www.enkasoutions.com). In an alternate embodiment, the netting pieces attach adhesively.
[0065] Fig. 14 illustrates an alternate embodiment of a ground cover 220 having crimped netting pieces 222 as the distributed asperity structural elements 28 attached to the thin membrane 224. Crimped netting comprises interwoven and crimped elongated members 226, 228 to form a mesh grid or netting 229. Crimped netting is available with porosity from about 50% to 95% based on aperture opening 230, wire or elongated member center-to-center spacing of the weave, and wire or fiber diameters. Contacting portions 232 of the crimped netting seat into the membrane 224, or if a meltable plastic material, fiisingly connect, to form the ground cover 220. In an alternate embodiment, the netting pieces attach adhesively.
[0066] The distributed asperity structural elements accordingly may alternatively comprise pieces of the three-dimensional reinforcement mats, crimped netting, or geocomposite pieces having three dimensional shapes featuring both porosity and asperity characteristics by which is defined foe air flow pathways in combination with vertically spaced asperity height relative to the membrane to which foe elements attach. The pieces may be discrete or mechanically interconnected by engaged ends of adjacent pieces. The pieces attach in any orientation, for example, randomly oriented or regular spaced. The pieces may be wholly or partially connected to foe membrane. For example, a partially connected piece may have an extending free portion that flaps in foe wind flow over and through foe asperity elements, which creates or adds additional disturbance to the wind flow. Embodiments include small pieces (2 inch by 2 inch, with a thickness for defining a vertical asperity height) or elongated pieces (for example, 2 inch wide by 12 inch long and a selected asperity height).
[0067] In one embodiment of the assembly of the discrete asperity element 28 with the membrane, the asperity elements 28 preferably are flowable. The asperity elements are flowable from the supply hopper for application to the thin membrane sheet during manufacture. The asperity elements 28 range in size from 10 mil to 6 inches, with the larger asperity elements generally having a lower distribution over the sheet. The asperity elements extend outwardly from the surface of the ground cover to a distal extent, for example, 10 mil to 6 inches (such as subject to rollability and distribution factors), more preferably 10 mil to 500 mil, or 20 mil to 80 mil.
[0068] The asperity elements are distributed across the surface of the membrane for use as ground cover sheet, for example, in fixed spaced-relation as rows and columns, offset rows and columns (that is, an adjacent row positions the asperity element in alignment with a gap between adjacent asperity elements in the adjacent row), or randomly. Smaller asperity elements may have a higher distribution density while larger asperity elements would have a smaller distribution density. The distribution density of the asperity elements ranges from about 5 asperity elements per square foot to about 10,000 asperity elements per square foot, more preferably from 10 asperity elements per square foot to 8000 asperity elements per square foot, and more particularly, from 15 asperity elements per square foot to 3000 asperity elements per square foot. For example, a geometric body providing a 10 mil distal height may have a density of 9200 per square foot while a geometric body providing a 50 mil distal height may have density that is significantly less.
[0069] Accordingly, a ground cover of a thin membrane with increased wind resistance is provided. A plurality of asperity elements of like material and even temperature (or range) are directed onto a thin membrane, during cooling and prior to final cooling, for readily adheringly to an upper surface of the thin membrane to provide an elongated sheet featuring a tall structure for ground cover usage. The supply hopper for the discrete asperity elements may optionally include the heater elements (heat source and temperature sensor), for providing a temperature control for example proximate the roller in a flat die cast extrusion process. The hopper holds small, shaped PE particles that disperse onto the thin membrane prior to final cooling. The hopper disperses the PE shapes (particles) at a predetermined rate and heat across and onto the thin membrane before the thin membrane cools. The particles adhere in a random distribution of fused, tall structures for use of the thin membrane as a wind-protected ground cover. In an alternate embodiment, the asperity elements adhesively attach to the membrane.
[0070) The formed thin geomembrane with attached asperity elements 28 readily installs over large area ground surfaces aS a ground cover, as shown in Fig. 3. The lower surface 26 of the thin membrane seats in engaging contact with the ground surface of a large area land site. The tall structure asperity elements 28 and the fibers of the non-woven batt layer 40 form impingements to the wind 60 flowing over the ground cover 39. This develops in situ the interior turbulent air flow layer 62 proximate the ground cover 39. As a result, the wind becomes turbulent with tumbling, turning, and twisting eddies 70 within the interior of the non-woven batt layer 40 and in the recesses 38 between the discrete asperity elements 28. The turbulent air flow layer resists wind uplift forces of the laminar flow on the geomembrane, separated by the transition turbulent air flow layer 64 from proximate an upper surface of the batt layer 40 to the vertically spaced laminar flow layer 66. Upwardly from the air flow boundary 44 the turbulence lessens and transitions in the transition layer 64 to the smooth air flow of the laminar flow 66 of the wind spaced vertically from the ground cover 39.
[0071] Similarly with reference to the embodiment illustrated in Figs. 13A and 13B, the mat 204 operates to overlie a surface such as a land site ground surface. The flexible vertically extended asperity-defining matrix generally 210 provides open air flow pathways illustrated by arrow 212 through the filaments 206 that interconnect by the fused interconnections of the filaments for a defined mat thickness 214. The tall structure asperity matrix form impingements to the wind flowing over the ground cover. This develops in situ the interior turbulent air flow layer proximate the ground cover. As a result, the wind becomes turbulent with tumbling, turning, and twisting eddies within the interior of the matrix. The turbulent air flow layer resists wind uplift forces of the laminar flow on the ground cover, separated by the transition turbulent air flow layer from proximate an upper surface of the membrane to the vertically spaced laminar flow layer. Upwardly from the air flow boundary the turbulence lessens and transitions in the transition layer to the smooth air flow of the laminar flow of the wind spaced vertically from the ground cover.
[0072] Similarly with respect to the embodiment illustrated in Fig. 14, the mesh 229 of the ground cover 220 overlying a surface provides a tall structure asperity extent with the openings in the mesh allowing turbulent air flow over the ground cover. The turbulent air flow layer resists wind uplift forces of the laminar flow on the ground cover, separated by the transition turbulent air flow layer from proximate an upper surface of the of the membrane to the vertically spaced laminar flow layer. Upwardly from the air flow boundary the turbulence lessens and transitions in the transition layer to the smooth air flow of the laminar flow of the wind spaced vertically from the ground cover.
[0073] Embodiments of the present invention preferably have a thin membrane with a thickness of up to about 80 mil, more preferably in a range of 30 mil to 50 mil and a plurality of distributed asperity structural elements defining a vertical distal asperity height relative to the membrane up to about 1,500 mil, more preferably of 10 mil to 1,000 mil, more preferably 20 mil to 400 mil. These relative dimensional features are heretofore unavailable in membrane structures but provided by the present invention. The membrane thereby is a carrier for attached positioning of the asperity structural elements in lateral spaced distributed relation extending vertically from the membrane to define a distal extent within a wind flow stream over a surface covered by the ground cover membrane but the membrane surprisingly does not need the increased foundational structure necessary for the prior art formation of the vertical asperity structural elements and thereby the present invention materially and surprisingly reduces material costs significantly.
[0074] With reference to the drawings, the foregoing discloses a method of making a ground cover, comprising the steps of: (a) forming an elongated thermoplastic membrane; and (b) attaching a plurality of discrete asperity structural elements to define a tall vertical profile. The asperity elements fusingly attach or adhesively attach. In the method, the membrane forms with a thickness in a range up to about 65 mil. Alternatively, the membrane forms with a thickness a thickness in a range of between about 20 mil and about 80 mil. The attached discrete asperity structural elements define a vertically spaced distal extent of the tall profile up to about 6,000 mil, alternatively, up to 1,500 mil, and alternatively the tall profile ranges between 50 mil and 1,500 mil. In some embodiments, the vertically spaced distal extent of the tall profile has a height that exceeds the thickness of the membrane.
[0075] In the method, the discrete asperity structural elements distribute randomly. Alternatively, the discrete asperity structural elements distribute in ordered rows. The discrete asperity structural elements distribute with a density in a range of 5 discrete asperity structural elements to 10,000 discrete asperity structural elements per square foot depending on asperity element size.
[0076] Alternatively, the method further comprises the step of adding a fabric batt overlying the discrete asperity structural elements.
[0077] The foregoing discloses a ground cover, comprising an elongated thermoplastic membrane having a thickness and a plurality of discrete asperity structural elements attached in spaced-apart relation to an upper surface of the membrane to define a tall profile, said asperity structural elements defining a distal extent vertically spaced from the upper surface. The thickness of the membrane is in a range up to about 80 mil and the distal extent of the tall profile in a range of between 10 mil to 6,000 mil. The height of the distal extent in some embodiments exceeds the thickness of the membrane. In an alternate embodiment, the ground cover further comprises a fabric batt overlying the discrete asperity structural elements. In an alternate embodiment, the asperity elements comprise a crimped mesh for attaching to the membrane.
[0078] The foregoing discloses a ground cover of a thin membrane with attached asperity elements that define a tall asperity profile for improved resistance to wind shear forces and a method of making the disclosed ground cover. Changes and modifications will be readily apparent to persons of ordinary skill in the art in view of the illustrative embodiments.

Claims

CLAIMS What is claimed is:
1. A method of making a ground cover, comprising the steps of:
(a) forming an elongated thermoplastic membrane; and
(b) attaching a plurality of discrete asperity structural elements in spaced-apart relation to define a tall vertical profile vertically spaced from the membrane.
2. The method as recited in claim 1, wherein the membrane is formed with a thickness in a range from 5 mil to 80 mil, optionally in a range from 30 mil to 50 mil.
3. The method as recited in claim 1 , wherein the discrete asperity structural elements define a vertically spaced distal extent of the tall profile from 10 mil to 6,000 mil.
4. The method as recited in claim 1 , wherein the vertically spaced distal extent of the tall profile has a height that exceeds a thickness of the membrane.
5. The method as recited in claim 1, wherein the discrete asperity structural elements are distributed randomly across the membrane.
6. The method as recited in claim 1, wherein the discrete asperity structural elements are distributed across the membrane with a density in a range of 5 discrete asperity structural elements to 10,000 discrete asperity structural elements per square foot.
7. The method as recited in claim 1, wherein the discrete asperity structural element comprises a geometric body having a shape selected from the group spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular.
8. The method as recited in claim 1, further comprising the step of overlying the membrane and attached discrete asperity structural elements with a fabric batt, optionally wherein the fabric batt comprises a nonwoven fabric.
9. The method as recited in claim 1, wherein the discrete asperity structural elements comprise a mesh grid.
10. The method as recited in claim 1, wherein the discrete asperity structural elements fittingly adhere to the membrane.
11. The method as recited in claim 1, wherein the discrete asperity structural elements adhesively adhere to the membrane.
12. A ground cover, comprising: an elongated thermoplastic membrane having a thickness; a plurality of discrete asperity structural elements attached in spaced-apart relation to an upper surface of the membrane to define a tall profile with a distal extent of the tall profile vertically spaced from the upper surface.
13. The ground cover as recited in claim 12, wherein the thickness of the membrane ranges from 10 mil to 80 mil, optionally in a range from 20 mil to 60 mil.
14. The ground cover as recited in claim 12, wherein the distal extent of the tall profile ranges from 20 mil to 6,000 mil.
15. The ground cover as recited in claim 12, wherein the distal extent of the tall profile exceeds a thickness of the membrane.
16. The ground cover as recited in claim 12, wherein the discrete asperity structural elements are distributed randomly across the membrane.
17. The ground cover as recited in claim 12, wherein the discrete asperity structural elements are distributed across the membrane with a density in a range of 5 discrete asperity structural elements to 10,000 discrete asperity structural elements per square foot.
18. The ground cover as recited in claim 12, wherein the discrete asperity structural element comprises a geometric body having a shape selected from the group spherical, oblong rectangular, square, pyramidal, diamond, jacks having a plurality of radial arms, shavings, and irregular.
19. The ground cover as recited in claim 12, further comprising a fabric batt overlying the membrane and attached discrete asperity structural elements, optionally wherein the fabric batt comprises a nonwoven fabric.
20. The ground cover as recited in claim 12, wherein the discrete asperity structural elements comprise a mesh grid.
21. The ground cover as recited in claim 12, wherein the discrete asperity structural elements fusingly adhere to the membrane.
22. The ground cover as recited in claim 12, wherein the discrete asperity structural elements adhesively adhere to the membrane.
PCT/US2024/047642 2023-09-20 2024-09-20 Ground cover membrane with a plurality of distributed adhered discrete asperity elements and method Pending WO2025064783A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US202363539490P 2023-09-20 2023-09-20
US63/539,490 2023-09-20

Publications (1)

Publication Number Publication Date
WO2025064783A1 true WO2025064783A1 (en) 2025-03-27

Family

ID=93013944

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2024/047642 Pending WO2025064783A1 (en) 2023-09-20 2024-09-20 Ground cover membrane with a plurality of distributed adhered discrete asperity elements and method

Country Status (1)

Country Link
WO (1) WO2025064783A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7131788B2 (en) * 2000-02-10 2006-11-07 Advanced Geotech Systems High-flow void-maintaining membrane laminates, grids and methods
KR100808733B1 (en) * 2000-08-11 2008-02-29 쓰리엠 이노베이티브 프로퍼티즈 캄파니 Friction Control Articles for Use Under Wet and Dry Conditions
US20100233427A1 (en) * 2007-11-02 2010-09-16 Tenax S.P.A. Composite for geotechnics, building and the like, with impermeable layer
IT201900021243A1 (en) * 2019-11-15 2021-05-15 Proge Plast Eng S R L Mat for synthetic grass playing fields.
US20220049450A1 (en) * 2020-08-14 2022-02-17 Watershed Holdings LLC Shear Resistant Geomembrane Using Mechanical Engagement

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7131788B2 (en) * 2000-02-10 2006-11-07 Advanced Geotech Systems High-flow void-maintaining membrane laminates, grids and methods
KR100808733B1 (en) * 2000-08-11 2008-02-29 쓰리엠 이노베이티브 프로퍼티즈 캄파니 Friction Control Articles for Use Under Wet and Dry Conditions
US20100233427A1 (en) * 2007-11-02 2010-09-16 Tenax S.P.A. Composite for geotechnics, building and the like, with impermeable layer
IT201900021243A1 (en) * 2019-11-15 2021-05-15 Proge Plast Eng S R L Mat for synthetic grass playing fields.
US20220049450A1 (en) * 2020-08-14 2022-02-17 Watershed Holdings LLC Shear Resistant Geomembrane Using Mechanical Engagement

Similar Documents

Publication Publication Date Title
EP2376693B1 (en) Patterned spunbond fibrous webs and methods of making and using the same
US5011642A (en) Method of making extruded article
US6605332B2 (en) Unitary polymer substrate having napped surface of frayed end microfibers
US9561612B2 (en) Method for manufacturing three-dimensional netted structure
US8757996B2 (en) Apparatus and method for manufacturing three-dimensional netted structure
US8568635B2 (en) Method for manufacturing three-dimensional netted structure having four molded surfaces
US9194066B2 (en) Three dimensional netted structure
US5904793A (en) Method and equipment for rapid manufacture of loop material
US4587148A (en) Flocked floor mat with foraminous layer
US6814912B2 (en) Heat treated high density structures
US20140037907A1 (en) Three dimensional netted structure
JP2008501475A (en) Reticulated web and method for producing the same
JP2004218116A (en) Reticulated structure loop forming apparatus, reticulated structure manufacturing apparatus, reticulated structure manufacturing method, and reticulated structure
US4333786A (en) Laminating
CA3047907A1 (en) Barriers and filters
JP2599760B2 (en) Extruded products and their manufacturing method
CN103261503A (en) Method for producing non-woven fabric, non-woven fabric, device for producing non-woven fabric, and support for producing non-woven fabric
JP2006520661A (en) Net structure and manufacturing method
WO2025064783A1 (en) Ground cover membrane with a plurality of distributed adhered discrete asperity elements and method
DE10326445B4 (en) Device for air conditioning a vehicle seat
WO2013087599A2 (en) Flow medium
WO2023044073A1 (en) Protective wrap for regulating fluid infiltration and methods of making, installing, and using the same
EP0140878A1 (en) Textile-like reticular product derived from film material
GB2096051A (en) Process for laminating
JPS6135310B2 (en)

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 24786638

Country of ref document: EP

Kind code of ref document: A1

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)