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r <br />'f <br />Goodbye, Polyethylene. . . <br />(Cent, from page 7} <br />chemicals. Poly is veo’tsusceptible to <br />puncture from aggregates, dried weed <br />stubs, and even mild foot traffic, and <br />once holes are made in the film it <br />becomes an Instant candidate for weed <br />infiltration. Even if the plastic sheets <br />survive a rigorous installation process, <br />there is virtually no aggregate to fabric <br />friction, which causes lighter organic <br />mulches to be “gone with the wind." <br />Worse still it is literally impossible to <br />Inqi any aggregate in place when using <br />poly film on slopes. The mgiority of the <br />aggregate uiually ends up sliding down <br />.. the visqueen to the bottom of the hill. <br />V| tateH>f-the>art technology now pro- <br />vMes lu with geotextiles, a series of <br />products that help to solve a multitude <br />of engineering and landscape problems <br />■Tlwy hswe finally di^laced polyeth>'lene <br />'from landscape use and put It back do­ <br />ing Jote for which is better suited. <br />Oeotextiles are synthetic fabrics <br />manufaaured from the polymers of <br />petroleum by*products and used in ex­ <br />posed contact with the earth. Tb be ef­ <br />fective, they must be strong and long <br />lived and unlike polyethylene, they <br />must be pervious to water and air while <br />filtering soil and inhibiting vegetat)ve <br />growth. <br />When used as a v eed control barrier, <br />these fabrics can reduce plant stress <br />whUe providing superior weed control <br />over long periods of time. No geoiextilc. <br />however, is totally effective as a weed <br />barrier. QuackgniK yellow nut sage and <br />planta such as bindweed with a <br />rhizominous growth habit have been <br />able to penetrate most fabrics, it is <br />therefore advized to pay proper atten­ <br />tion to creating a weed-free environ­ <br />ment before fabric installation. <br />'niere are many different types of geo- <br />taxtiles with variations in material com- <br />poalUon, manufacturing processes, <br />strength, stsblUty, and functionality. It <br />la Imponant that users realize that these <br />differmcas exist and that no product is <br />intended for all applications. Some of <br />thase fabrics have very specific capu- <br />biUtiea They should be reviewed care­ <br />fully and chosen wisely. <br />The woven products seem to have <br />more restrictions and in general are ap­ <br />parently best suited for use as silt fences <br />and in other exposed, above-ground ap­ <br />plications. They would be especially <br />ustfu! in nursery or greenhouse settings <br />as a base under container or B&B hold­ <br />ing stock. AnoUter effective use would <br />be in the area of ground stabilization, <br />especially where permeability is no.' s <br />critical factor <br />The non-wovens are clearly better <br />choices in situations w*ith high airwate.' <br />permeability needs. The> work equally <br />well as above-ground weed barriers <br />• A • V*«!t 10Ri'i • G*‘****f* <br />•^m <br />Definitions for Landsca <br />4 . , • . • - . * . <br />Air Flow: The ability of a fabric to permit the pas^e of air through Ac, <br />plane of the fabric ' ./ ' .4. ' <br />Bonding: Tlie process of attaching the randomly pbced fQ>eis ofn no&wovu f ^ <br />fabric into webs or sheets b>’ means of.heai, (m^cai/rea0on'.‘TOtar^^ <br />ment or adhesives. V*-V.‘' <br />Bonding: A method of attaching the flbeis iiua mn-waven <br />by applying a chemical to soften the fibers and, then .paaaihglhe-fabric4)e^<t ' <br />ween two pressure roUeri As the fibers haiden„a bondls^PRhed at4he'*aEpa4^', <br />Coefnclont of Friction: The resistance to sUppagd betW^ ih^miii^^ “ <br />the substrate or the fabric and the aggregate<U^*V/** <br />Flltrationi The ability of a fabric to prevent Uiq piso^ of fUw^gtalncd pi^ <br />ticies through its plane and still not inhibit the n^ai^piMaiij|^i^ <br />GeotextUee: Porous woven and non-woven synthetic ^rics-whi^aue us--- ? <br />ed in expoeed contact with the soil. They protide..ndbiUty,.^hS]^ <br />change, weed control, filtration and drainage in a variety of iaiidaeape; , <br />licultural, erosion control and ettgti»e«n»8 <br />Heat Bonding! a method of attaching the fibera in 4^npn*iivdt^ fU>ifc'by^‘ <br />passing the fabric between two heated loUen, wldch al^^«np|^ prani^tQ <br />the web. Where any two flben inteisect, .a bond'b (9med aa..^4{oftened <br />flbeiB cool and harden. - ...^ • <br />Mullen Bunt: The ability of a fabric to teaist.riipture.by pc^n^appUed...^ <br />at right angles to the plane of the f»Pnc <br />Needlepunchlngi A metltod of bonding non-wovm fa^.wheie by msehes'' <br />of multi-barbed needles are passed in and;out,offabric'w^ an^ <br />mechanically interlock the fibers amongst th.ems^lvei,'^ . • Vi- ' '=•' * <br />Non-woven fabrics: Those fabrics ha\ing a random orientation ol^jQbaia that^- ^ <br />run in any and all direaions within the fabilc.’Xhib*'M.iisua^jnanuto <br />tured by the dry laid method or the more commoidy uiredapunboi^ iiroceiu; ^ <br />and their strength is relatively equal in aU direetionis-. <br />Planar flow: Tl.e fabric property w'hlch peimltl waterto'be tiinsinitted'’' <br />laterally within the plane of the fabric ' >•, ^ J <br />Polyester: A type of synthetic material used in the manufacQueipf many <br />types of fabric and having veiy durable andstable.iduuacter|sticsr.ItJg a!.* <br />term describing a specific polymer type deyiriop;^ from<a.ptTOleum • <br />derivative. • • <br />I\)lyethylene: A polymer of ethylene, a petroleum derivWve thid|MBes tha* • <br />• - "• ^ V•• <br />when* Aggregate is used or in below­ <br />ground drainage situations. Like the <br />woven fabrics, they are quite functional <br />in ground stabilization uses, especially <br />where permeability is a factor <br />For our purposes m this review, let us <br />analyze the fabric characteristics that <br />are most desireable for a wec'J barrier <br />application. <br />A fabnes first requirement is to be <br />higlily air and water permeable and yet <br />be an effective weed barrier. The non- <br />wovens seem to be the most qualified <br />here — with the needle-punched lead­ <br />ing the way only because of their slight­ <br />ly better permeability. <br />The fabric should come in rol! weights <br />lengths and widths ic fit jou needo anu <br />provide an ease cf iiandiing ami mstalla- <br />tion Some manufacturers provide only <br />a iimiiet! selectlo.*^ ui roil sizes Overall <br />strength is another key factor and <br />several categories provide us with in­ <br />sights in this area. Ideallv*; UV resistance <br />should be high, but if the fabric is w'ell <br />covered with mulch or buried, this <br />becomes less of a consideration. <br />If the geotextile Is installed over very <br />rough, ungraded ground, an ability to <br />conform to the substrate is desireable, <br />especially when rip rap or other heavy <br />aggregate is placed on the fabric or if <br />heavy traffic is anticipated. The most <br />flexible fabrics seem to do the best job <br />here <br />Ease of cutting for close placement <br />around plants, vacuum breakers, valve <br />boxes and other obstacles should not be <br />overlooked. Much time and frustration <br />can be expended on fabrics which can­ <br />not be cut straight or easily or which <br />unravel o.- continue to le^r when used.