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Bentofix®INNOVATION & QUALITY IQ

The Inventor of Needle-punched Geosynthetic

Clay Liners. Outstanding Quality and Longest Experience.

Bentofix® - The Original!

Bentofix® IQ addresses four subjects key to understanding geosynthetic clay liners (GCLs): Technics,

Quality, Application and Ecology. It describes the intelligence and importance of this product type,

which was invented by NAUE in 1987, and highlights the intelligent use of needle-punched GCLs in

sealing applications. Today, the Bentofix® IQ approach is guided by the classical elements of water,

fire, earth and air as critical issues such as proper GCL production, design, application and installa-

tion. Bentofix® IQ encourages GCL users to utilize these classical elements to understand those four

key GCL subjects: Technics (water), Application (earth), Quality (fire) and Ecology (air).

High-Swelling BentoniteAll geosynthetics have their indi-vidual advantages. For geosyn-thetic clay liners, the swelling ca-pacity and “self-sealing” charac-teristic of the sodium bentonitecore truly separate them fromother barrier materials. Swellingoccurs during contact with mois-ture and fresh water. However, ifthe GCL is punctured during con-struction, this swelling reaction is known as self-sealing and is a characteristic not found in anyother single or composite geo-synthetic material and unlikely

to be found in traditional claybarriers. The key rests in how GCLsencapsulate sodium bentonite, aunique, natural material that is the result of volcanic ash set-tlements from more than 50 million years ago.

Bentonite qualities:The exceptional qualities of sodiumbentonite have only been fully realized in the past centuries.Sodium bentonite is characterizedby the lowest known permeabilityof naturally occurring geologicalmaterials and a high absorptioncapacity. Its swelling ability is so

significantly greater than conven-tional clay that a relatively thinlayer of it, properly secured be-

tween geosynthetics, can be usedin place of thick layers of compactedclay. This extraordinary swell cha-racteristic stems from its montmo-rillonite content. Montmorilloniteswells approximately 900 percentwhen in contact with fresh water.

Importance of powder:Bentofix® uses high-swelling, so-dium bentonite clay, which has alower permeability than calciumbentonite. Bentofix® also uses thepowdered form of this bentonite,which is unique in GCL manufac-turing today and allows a very constant distribution within the

GCL. Products with more granularbentonite begin their service life in the field with voids. While

bentonite’s swel-ling capacity ise x c e p t i o n a l ,granular voids do not close asquickly as pow-dered bentonite.Powdered ben-tonite swells im-mediately in con-tact with freshwater and acts asa barrier.

Testing:NAUE utilisesstringent test-ing regimes and frequencies for both raw materi-als and finishedproducts. The

bentonite suppliers conduct rigorous testing, such as sieveanalysis to assure the powder qual-ity, which is essential to ensuringimmediate swell performance orthe montmorillonite content.NAUE’s quality control bentonite

testing includes ASTM Interna-tional’s swell index (D5890) andfluid loss test method (D5891).Also, NAUE conducts water ab-sorption testing (in accordancewith DIN 18132) and methyleneblue (MB) absorption testing. MBtesting is not common among GCLmanufacturers, but it is standard

for NAUE. These single tests arenot fully indicative of permeabil-ity, but together with NAUE´sknowledge and database of per-meability results over the decadesallow an important understandingof the overall bentonite perform-ance combined with the NAUEneedle-punching technology.

Bringing it together:Once the sodium bentonite’s highquality is verified and approved, it can be used in the Bentofix®GCL manufacturing process. A uni-form core layer of it is sandwichedbetween two outer geotextile components, such as through needle-punching, which ensuresthe bentonite erosion stability and gives the GCL the necessarystrength properties as well as du-rability. Consistency of the ben-tonite quality, uniformity in its thickness in the GCL, and the geotextile protection enable a single Bentofix® layer to outper-form thick compacted clay land-fill liners, under roads for environ-mental protection, in dams anddykes, as secondary containmentand in other applications.

Bentofix® IQBentonite

»When powder turns to power«

Fig. 1Swell volume of bento-nite measured with

various liquids andconcentrations.

The IQ of Technics: Excellent hydraulic barrier, high shear performance, robust components, durable geosynthetics

High-Quality ComponentsBentofix® is a needle-punched,self-sealing barrier compositematerial. In addition to a coresodium-bentonite layer, Bento-fix® GCLs excel in versatile barrierapplications due to the out-standing strength and quality of their components. The bal-anced combination of polymericfibres and naturally occurringclay creates a long-term sealingsystem which relies on each single component.

Nonwovens: NAUE’s extensive history of suc-cess in nonwovens manufactu-ring is key to the manufactureand performance of Bentofix®.The uniform layer of sodiumbentonite is secured by millionsof needle-punched, nonwovenstaple fibres, a process that elim-inates the concerns of the lowfriction coefficient of bentoniteby transferring the strength to the nonwoven geotextile. Also, NAUE does not rely upon another company’s nonwoven product. Instead, NAUE selects and purchases its own fibres for reinforcing the surface ofBentofix® GCLs. It is the same expertise utilised in the manu-facture of the internationally successful Secutex® line of non-woven geotextiles. Manufactu-red from 100 % synthetic fibres, the nonwoven geotextile outerlayer of Bentofix® ensures long-term stability.Scrim reinforcement:The carrier layer of every Bento-fix® GCL has a slit film scrim re-

inforcement geotextile as a car-rier layer. This component ismainly needed for on-site hand-ling and allows the pulling anddragging on the GCL for properplacement without too muchelongation of the GCL. Com-bined with the proprietary heat-treating process (Thermal Lock),it is used to anchor and morepermanently lock the needle-punched fibres for superior long-term internal shear performance.

Additional bentonite:For projects that may require additional bentonite to ensurea proper seal, NAUE offersBentofix® BFG. This series isjust as robust, but in addi-tion to the normal layer ofhigh-swelling bentonite it fea-tures a covern o n w o v e n geotextile that has been uni-formly impreg-nated with asecond layer ofsodium ben-tonite powder.This is impor-tant for instal-lation security.Some applica-tions requireadditional ben-tonite at thepanel overlaps.Bentofix® BFG

provides the solution. All otherBentofix® types have this sametechnology in a 500 mm widestrip on both longitudinal edgesto ensure sealed overlaps in this area.

The “X” Factor:While the strongly bonded geo-textiles hold a GCL’s bentonitelayer in place and improve thecomposite material’s durabilityand performance, gas can flow

through in the first phase of anapplication if the bentonite is not yet hydrated; or desicca-tion can influence the perform-ance of the GCL’s bentonitelayer. This can be issue for somespecific situations, such as wa-terproofing in areas where radon

gas occurs or applications withlow confining stresses. NAUE’smost recent GCL advance,Bentofix® X, exemplifies howmodifications to GCL product de-sign can be made to anticipatethe special challenges of partic-ular sites. The uniform layer ofpowder sodium bentonite inBentofix® X is encapsulated be-tween a slit-film woven and astaple-fibre nonwoven geotex-tile. The woven fabric is coatedwith a low-permeability polymerpolyolefin coating to achieve an immediate barrier prior to hydration.

Quality Control:Regardless which of these com-ponents needs to be tested, it is all done in-house under na-tional or international regimesin an ISO 9001-certified facility.Where applicable, CE marking is available.

Bentofix® IQComponents

»Only the best ingredients make it a success«

Fig. 2Range of Bento-fix® permeation in correlation to bentonite mass per unit area

The IQ of Quality: High-swelling bentonite, quality-controlled components, superior manufacturing method, years of research experience

Superior ManufacturingIndependent construction qualityassurance (CQA) monitoring onconstruction sites is increasinglyrequired, but the roll of CQA andsecondary manufacturing qualityassurance (MQA) tests are ren-dered largely moot if the mate-rials are manufactured and testedproperly before site delivery.NAUE ensures a high level of man-ufacturing quality control (MQC).

Mechanical strength:To ensure superior durability and long-term performance ofBentofix® GCLs, rigorous stan-dards are adhered to in the manu-facturing process. Among themare numerous mechanical checksand tests. The needle-punchmethod of manufacturing bondsthe central, uniform layer of ben-tonite and the outer geotextilelayer with the strength of morethan two million needle-punchednonwoven fibres per square metre.

This balanced combination cre-ates a long-term sealing systemwith high shear strength. TheThermal Lock Process is a pro-prietary heat-treating processused to modify and more per-manently lock into place theneedle-punched fibres. Tensileand peel testing confirms thestrength and security of thebond. NAUE’s technical expertseven developed a correlation

between the peel test and the internal shear strength ofBentofix®.

Hydraulic suitability:The extensive testing NAUE performs on their high-quality, powdered sodium bentonite andon finished material rolls verifiesthe suitability of Bentofix® asan exceptional barrier for a great range of contain-ment applications, alsodue to the superior, im-mediate swelling char-acteristics of powder-ed sodium bentonite.NAUE’s bentonite sup-pliers verify the ben-tonite powder qualitywith various tests whichare also confirmed uponarrival at the GCL plant.Furthering the verifica-tion process, NAUE’squality control testingincludes testing of the

index flux, permittivity and hy-draulic conductivity accordingto ASTM, DIN and CEN stan-dards. With over 35 flexible wallpermeameters NAUE is capableof maintaining a high testingfrequency over the entire year,which is not commonly utilisedby other manufacturers.

Testing frequencies and facilities:NAUE’s ISO 9001-certified lab-

oratory and manufacturing pro-cesses combine to provide theessential documentation andmanufacturing quality controlfor confidence in GCL design,specification, installation andperformance. While standardMQC regimes ask for a mini-mum test frequency, NAUEcommonly tests at higher fre-

quencies than requested ordone by other manufacturers.Furthermore, NAUE’s 24-hourfacility conducts MQC tests onfinished rolls to ensure thequality of both the compo-nents and the security of theirbond. Since NAUE produces itsown nonwoven geotextile lay-ers from specially selected sta-ple fibres, it can also providethe detailed certification ofthese components. CE Markingand other special specificationassisting labels are avai-lable.

The end result:The dedication to manufacturingquality and decades of researchand experience enable Bentofix®GCLs to significantly outperformconventional, expensive, thickclay layers on all measures: cost,safety, long-term durability, permeability, ecologically, etc.The uniform core of powdered

sodium bentonite is securedthrough the needle-punchingprocess and the bond is rein-forced by the Thermal LockProcess. Rigorous and frequenttesting confirm the quality ofthe individual components andthe composite Bentofix® rolls, as well as verify their qualifica-tion for numerous hydraulic de-signs and barrier system needs,such as for landfill capping, en-vironmental protection in trans-portation, dam linings, second-ary containment, levee con-struction and much more.

Bentofix® IQManufacturing

Fig. 3Maximum tested waterhead over aGCL overlayinga geonet, resp.gravel layer(grain size 6mm) as sub-base vs. carriergeotextile massper unit area

The IQ of Applications: Resists high water heads, ideal environmental protection, ideal barrier for landfills, versatile sealing applications

»Made right, made to last, made to seal«

Years of Field Experience, Research and DevelopmentNAUE’s long history of materialsdevelopment, testing and manu-facturing have made the varioustypes of Bentofix® geosyntheticclay liners robust, versatile pro-ducts that meet the highest safe-ty standards and provide excep-tional cost efficiencies. When inneed of an effective, long-termbarrier system, choosing Bento-fix® will ensure quality, preserveour natural environment, and re-duce construction costs and time.

Innovation: Since the 1960s, NAUE has usedneedle-punching as one methodof creating materials. The expert-ise gained during those early yearsled to the discovery of how to useneedle-punching in the manufac-ture of GCLs. This invention oc-curred in 1988, and the processrevolutionized the field. Ratherthan just bonding an independentgeotextile and a layer of clay, theneedle-punching method usedhere was developed to be specificto GCL manufacture and perform-

ance. NAUE even developed spe-cial needles to make this processpossible. The advance enablednot only the rapid, safe produc-tion of uniformly thick GCLs butefficient shipping of GCLs in rolls.

Also of note, the previously lowfriction coefficient of the ben-tonite clay used in GCLs ceased tobe of concern because of needle-punched geotextile encapsula-tion. This new method of manu-

facturing transferred the shearstress from the clay to the highlyengineered geotextile. Other in-novations from NAUE include be-ing the first to impregnate thetopside and the longitudinaloverlap areas of the GCL withpowdered bentonite, adding asand ballast layer on top of theGCL for underwater installation,thermally locking the needle-punched fibres for long-termshear strength and much more.Also, NAUE has, from the begin-ning, manufactured GCLs with

scrim-reinforcement for securehandling on site.Testing and Standards:NAUE’s experts have been and areactive in international committeesand societies, helping to write new

standards to improve the geosyn-thetics field and publishing tech-nical articles to transfer knowledgeof geosynthetics manufacture, in-stallation and performance. NAUE’sISO-accredited laboratory performs

rigorous tests on all the compo-nents used in Bentofix® and haseven helped to develop tests forstandardization, such as the peeltest. NAUE has also helped to establish a minimum thickness forthe textile component to ensureproper bentonite encapsulation.Research and development: From the beginning of NAUE´sGCL involvement, one main taskhas been to remain continuouslyinvolved in research. This questhas included the excavation ofmultiple sites to investigate GCL

properties, building lysimeters to collect permeation data andverify the sealing efficiency ofBentofix®, researching the dif-fusion rate and long-term shearresistance of GCLs, investigating

hydraulic conductivity under var-ious confining stresses, gradientsand against different liquids, correlating peel strength agai-nst internal shear strength, andmany other developments.

Awards: In 2008, the Inter-national Geosyn-thetics Society(IGS) honouredNAUE GmbH & Co.KG with the soci-ety’s highest award, the IGS Award, foroverall excellence.The award recog-nised NAUE’s nu-merous manufac-turing innovations

and contributions to the fieldof geosynthetic engineering, the most significant of whichhave involved geosynthetic clayliners. In addition to the manu-facturing advances, NAUE’s re-search and installations aroundthe world have also benefittedthe entire geosynthetic engi-neering community. Key devel-opments include self-sealingoverlaps in GCL panels, under-water installations with GCLsand sandmats, and landfill capping.

Bentofix® IQExperience

»The doors of wisdom are never shut«

Fig. 4Self sealing

performance of long-term

installed Bentofix®

GCLs

The IQ of Ecology: Reduced energy costs in production, long-lasting designs, low transportation costs; reducing carbon footprint

Bentofix® Thermal Lock geosynthetic clay liners (GCLs) are needle-punched, reinforced composites that combine two durable geo-textile outer layers and a uniform core of high-swelling powder sodium bentonite clay. This construction forms a shear-resistant hydraulic barrier with self-sealing characteristics. When hydrated with fresh water, the bentonite swells and forms a low per-meability gel layer, the hydraulic performance of which is equal to or better than traditional, thick compacted clay liners.

Additionally, the proprietary heat-treating process – Thermal Lock – permanently locks the needle-punched fibres, increases the pull-out resistance of the fibres and ensures long-term shear resistance. Bentofix® GCLs are impregnated with a 500 mm wide, uniform layerof bentonite in both longitudinal directions. This enables an immediately sealed overlap without the need for further bentonite ad-dition on site. Bentofix® BFG is also impregnated with an additional, uniform layer of sodium bentonite powder across its nonwovensurface. This advance is ideally suited for pond and waterproofing applications, since the outer layer of the nonwoven geotextile creates an intimate contact zone in overlap areas, such as with concrete surfaces.

Bentofix® GCLs are part of an important trend toward the combined use of geosynthetics and clay materials in barrier applications as a stand-alone liner system and in the synergistic use of GCLs and geomembranes to maximise liner system efficiency.Bentofix® Thermal Lock GCLs are utilized in but not limited to the following applications: landfill caps and lin-ers; environmental protection under roads, railways, and airports; dam and dyke sealing;vertical barriers; ponds; waterproofing; and secondary containment.

NAUE’s most recent GCL development, Bentofix® X, exemplifieshow modifications to GCL product design can be made to anticipatethe special challenges of a particular site. Bentofix® X is a polyolefinpolymer-coated GCL. The woven fabric is coated with a low-permeabilitypolymeric polyolefin coating to achieve an immediate barrier prior to hydra-tion. Bentofix® X is an advance for GCLs in some specific applications, such aswaterproofing, oil and gas tank farms, landfill capping and cover systems or wherehigh hydraulic gradients are present.

The information contained herein is the best to our knowledge, true and accurate. There is no implied or expressed warranty.© 2011 by NAUE GmbH & Co. KG, Espelkamp-Fiestel, Germany · All rights reserved. · Status 11.02.2011

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and Bentofix® are registered trademarks of NAUE GmbH & Co. KG.

NAUE GmbH & Co. KGGewerbestrasse 232339 Espelkamp-FiestelGermany

Phone +49 5743 41-0Fax +49 5743 41-240E-Mail info@naue.comInternet www.naue.com

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