Term	Description
Anchor Trench	An excavated ditch in which the edges of a geotextile or geomembrane materail are buried in order to hold it into place.
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Berm	A soil ridge often forming the outer edge of a lagoon,lake or pond.
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Breaking Strength	The ultimate tensile strength of a material per unit width. Usually given in k/N metre width
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Butyl Rubber	A synthetic rubber based on isobutylene and a minor amount of isoprene.It is vulcanisable and is highly impermeable to gases and water vapour,with good resistance to ageing,chemicals and weathering. (Two layer membrane)
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Clogging	The movement by a mechanical action or hydraulic flow of soil particles into the voids of a fabric and retention therein,thereby reducing its permeability.
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Creep	The slow change in length or thickness of a material under prolonged stress.
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Deformation	The change in size of a material under load from its original pre-loaded dimensions.
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Drainage Medium	The material used in a drain (usually crushed stone) through which water passes.
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Elasticity	The property of matter by virtue of which it tends to return to its original size and shape after removal of the stress which caused the deformation.
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Elongation at Break	The percentage of elongation corresponding to the maximum load.
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Fabric - Composite	A textile structure produced by combining different types of geotextiles into a single unit.
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Fabric - Knitted	A textile structure produced on knitting machines.
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Fabric - Nonwoven	Nonwoven geotextiles are usually either needlepunched or heat bonded fabrics.
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Fabric - Reinforcement	Usually an open-weaved textiled mesh,called scrim,which is used to add structual strength to another textile or geomembrane.In the case of nonwoven fabrics, the scrim is usually needled into the material at the time of manufacture.In the case of geomembranes the scrim is usually enclosed between two membrane sheets which are bonded together.
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Fabric - Woven	A planar textile structure produced by interlacing two or more sets of fibres on a loom,usually at right angles.
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Film	A very thin sheet of plastic
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Filter Cloth	A geotextile whose immediate engineering function is to act primarily as a soil filter.
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Filtration	The placing against a soil of a permeable material containing pores sufficently fine to allow water to pass out of the soil,but not to permit the passage of soil particles.The permeable material is called a "filter" or "filter fabric" in the case of a geotextile - if it is granular,then it is usually referred to as the "filter medium"
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Firestone Pond Liner	This is a cured single-ply synthetic rubber membrane made of ethylene,propylene, diene, terpolymer. (EPDM)
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Flow Regime	This term can either describe the steady groundwater conditions at any particular locality or it can describe the micro-flow conditions adjacent to a soil/filter interface i.e. laminar,turbulent,radial,planar.
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Geocell	A three-dimensional geosynthetic structure filled with granular material to form a contained mattress for increased bearing capacity over soft subsoils.
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Geocomposite	A manufactured material using geotextiles,geogrids and/or geomembranes in laminated or composite form.
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Geogrid	This terms usually refers to a rectangular grid made of polymer,which although it is rather rigid and unlike a textile in the conventional sense,still comes under the heading geotextile in many definitions - it is probably more suitably referred to as a "geosynthetic"
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Geomembrane	An impermeable membrane used primarily in the construction of ponds,lakes etc.
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Geosynthetics	The generic classification of all synthetic materials used in geotechnical engineering applications.
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Geotextile	Any permeable textile,mesh,net or even grid,used in contact with soil or rock.
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Greenseal	The polymer EPDM,ethylene-propylene rubber,is produced through co-polymerisation of ethylene,propylene and diene monomer,producing a ploymer made up of saturated linear macromolecules with a paraffinic structure. (2 layer membrane)
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Heat Bonded	This terms describes a textile that has been subject to heat and pressure,whereby individual fibres have partially melted and bonded at their intersection points.
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Heat Seaming	The process of joining two or more thermoplastic films of sheets by heating areas in contact with each other to the temperature at which fusion occurs.
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Hydrophillic	Will absorb water (attracts water)
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Hydrophobic	Will not absorb water (repels water)
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In-Plane	Refers to the plane of a geotextile.Usually associated with hydraulic conductivity in connection with how much water can be conducted along,within a geotextile,as opposed to the ease with which a geotextile can permit water to pass across is thin dimension.
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Isotropic	Equal strength in all directions
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Laminar Flow	Fluid follows specific flow paths,obeys Darcy's Law when seeping through porous media.
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Lapped Joint	A joint made by placing one edge of a textile or a membrane partly over another surface and bonding or sowing the overlapping portions.The purpose of joining may be to waterproof a membrane lining of a lagoon,or to save money over a large textile area by saving lap fabric,or to provide continuous structual strength in the weft direction of a textile layer by sewing adjacent geotextile sheets together.
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Membrane	A continuous sheet of material.Usually,it carries the connotation of being impermeable,although this is not strictly true.
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Modulus	The stiffness of a material when subject to stress
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Monofilament	A synthetic fibre made from a single polymer
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Needle Punched	This refers to a textile that has been mechanically bonded.Fibres are laid on a moving belt and then punched through repeatedly with barbed needles.The needles entangle the fibres,causing them to form a continous textile having tensile strength.
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Neoprene	Also known as polychloroprene - a generic name for a synthetic rubber.Resistant to ozone,to aging and some oils.
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Nitrile Rubber	A family of copolymers of butadiene and acrylonitrile that can be valcanized into tough oil -resistant compounds.Blends with PVC are used where ozone and weathering are important requirements in addition to its inherent oil and fuel resistance.
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Nonwoven	Refers to needlepunched and heat bonded fabrics only.Knitted fabrics are technically not woven,but are usually covered by this word.
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O	Symbol representing hole diameter
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Particle Size Distribution	A term describing the range of particle sizes in a soil.A Particle Size Distribution Curve is a graph showing the percentage fractions by weight of different sizes of particles in a particular soil sample.It is undertaken by the laboratory sieving of a soil.
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Permeability	In the context of geotextiles,this usually means the ease or otherwise with which water can travel within or pass through a geotextile or granular medium.
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Plasticiser	A plasticiser is a material added to a plastic or rubber to increase its ease of working or flexibility.
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Polyester	A material in which the fibre-forming substance is any long-chain synthetic polymer composed of ester of a dihydric alcohol and terephthalic acid.
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Polymer	A material formed by the chemical combination of monomers with either the same or different chemical compositions.Plastics,rubbers,and textile fibres are all high-molecular-weight polymers.
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Polymeric Liner	Plastic or rubber sheeting used to line waste disposal sites,ponds,lagoons or canals.
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Polyvinyl Chloride (PVC)	A synthetic thermoplastic polymer prepared from vinyl chloride.PVC can be compounded into flexible and rigid forms through the use of plasticisers,stabilizers,fillers and other modifiers.
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Pore,Slot,Aperture	The holes through a pipe,a mesh or a geotextile
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Puncture Resistance	The extent to which a membrane or geotextile is able to withstand the penetration of an object without perforation.
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Rubber	A polymeric material which,at room temperature,is capable of recovering substantially in shape and size after removal of a deforming source.Refers to both synthetic and natural rubber.Also called elastomer.
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Scrim	A woven,open-mesh reinforcing fabric made from continuous-filament yarn,used to reinforce nonwoven geotextiles or geomembranes.
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Soil Migration	The transportation of soil particles within a soil,caused by the internal flow of water.
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Spun-Bonded	A fabric manufacturing process wherein continuous or staple monofilaments are spun,formed into a sheet and then subject to heated pressurised rollers which weld the filaments together at their contact points.
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Tear Strength	The force required to tear a specimen of geotextile or geomembrane.Test results are dependent on direction of tear,specimen geometry and rate of tear.
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Tenacity	A measurement of fibre strength
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Tensile Strength	This term means the maximum tensile stress per unit of original cross-sectional area applied during stretching of a specimen to break.It is described in units of force per unit area of specimen cross section.
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Termination Bar	Profile manufactured from a range of materials used for terminating a geomembrane sheet at the top against an upright wall.
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Thermoplastic	Capable of being repeatedly softened by increase of temperature and hardened by decrease in temperature.Most polymeric membranes are supplied in thermoplastic form because the thermoplastic form allows for easiler seaming.
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Ultimate Elongation	The elongation of a stretched specimen at the time of break.Usually reported as percent of the original length.Also called elongation at break.
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Ulta-Violet Degradation	The breakdown os a geotextile's fibre or a geomembranes polymer when exposed to light.
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Vulcanisation	A chemical process through which a rubber compound's physical and chemical properties are improved.
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Warp	Filaments running in the direction of a weaving loom i.e.the direction in which the fabric moves during manufacture.
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Weft	Filaments running usually at 90° to the warp direction of a weaving loom.The weft fibres are placed between the warp fibres by means of a shuttle.