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Bentofix® X Geosynthetic clay liner

Naue Bentofix® X geosynthetic clay liner is a multicomponent PE-coated GCL for landfill, waterproofing and slope sealing.

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  • Close-up of a Bentofix® X bentonite mat (geosynthetic clay liner) showing the bentonite and PE coating layers.
  • Construction worker guiding a large Bentofix® roll being lifted on a construction site.
  • Aerial view of a large open-pit mining site where Bentofix® X was installed, with terraced earthworks, lined containment areas, and a water pond.
  • Bentofix® X is a multicomponent GCL/GBR-C with an extrusion-coated PE layer on the carrier side.
  • Dual barrier: the PE layer seals immediately on installation; the sodium bentonite core self-seals on hydration.
  • Three grades: X2 (smooth PE), X5F and X10F (structured PE) - full range in technical data.
  • CE (CPR), ISO 9001, DIN 18200, BBA-HAPAS (no. 05/4256), ÖNORM - full list in technical data.

Bentofix® X is a multicomponent geosynthetic clay liner for containment sealing, waterproofing and landfill engineering. You install it between the subgrade and the protective cover layer. The PE coating provides an immediate hydraulic barrier from day one. The sodium bentonite core self-seals on contact with water and re-heals after damage.

Standard geosynthetic clay liners function via bentonite hydration. Aggressive leachate, vapour and gas can penetrate the barrier, and ion exchange from calcium-rich leachate can degrade the bentonite over time. Bentofix® X solves this: The PE layer acts as an immediate barrier against gas, methane, radon and aggressive chemicals.

One geosynthetic replaces three site materials: clay liner, gas membrane and root barrier. Less cover soil is required than in standard GCL applications. This reduces excavation, transport and disposal costs.

The PE layer achieves k ≤ 10⁻¹⁴ m/s (EN 14150). The composite achieves internal shear strength ≥ 35 kPa (EN ISO 12957-1, 900 cm², 20 kPa). The X5F variant achieves interface friction ≥ 9 kPa against 300 g/m² Secutex® nonwoven at 20 kPa (ASTM D6243). X10F achieves interface friction ≥ 15 kPa against 300 g/m² Secutex® at 20 kPa (ASTM D6243). BBA-HAPAS certificate no. 05/4256 covers X2 BFG 5300 for concrete waterproofing applications. ÖNORM covers X6F and X10F NSP 5300 ÖN variants.

Bentofix® X geosynthetic clay liner functions:

  • Barrier

    Barrier

    Bentofix® X creates a hydraulic and gas barrier. The PE layer (k ≤ 10⁻¹⁴ m/s) acts immediately. The bentonite layer (k = approx. 1.0 x 10⁻¹¹ m/s) self-seals on hydration. Together they provide two independent barriers.

  • Separation

    Separation

    The geotextile layers keep the bentonite core in position and separate it from adjacent soil layers during installation and throughout service life.

  • Protection

    Protection

    The PE coating protects the bentonite against desiccation, ion exchange, root penetration, and piping over coarse aggregates. Also acts as chemical protection barrier in aggressive environments.

Bentofix® X geosynthetic clay liner advantages: dual barrier performance and chemical protection

Bentofix® X delivers advantages in a chemically exposed environment. The PE coating transforms a single-barrier system into a multicomponent barrier with immediate protection and extended service life in demanding environments.

  • Speed

    Immediate gas barrier

    The PE layer acts from day one, before bentonite hydration. No waiting period. Effective against methane, CO₂, radon and vapour. Equivalent performance to adding a separate geomembrane.

  • Chemical and ion exchange protection

    Ion exchange and chemical protection

    PE coating shields the bentonite from calcium, magnesium and potassium ions in aggressive leachate. Prevents bentonite degradation in landfill and mining applications.

  • Dessication resistance

    Desiccation resistance

    PE layer prevents moisture loss from the bentonite core. Critical in arid climates and landfill capping applications with seasonal drying.

  • Slope friction

    Superior slope friction

    X5F (≥ 9 kPa vs. 300 g/m² Secutex® at 20 kPa, ASTM D6243). X10F (≥ 15 kPa vs. 300 g/m² Secutex® at 20 kPa, ASTM D6243). Enables confident slope stability design at 1V:2.5H and steeper.

Application areas

Typical applications:

  • Landfill base liner systems under high leachate head
  • Landfill capping and closure systems with desiccation risk in arid climates
  • Gas containment liners for landfill gas management and methane capture
  • Reactive waste containment and leachate management with aggressive chemistry

Bentofix® X is a multicomponent geosynthetic clay liner for landfill base liner and cap systems. The PE coating provides an immediate gas barrier from day one, critical in landfill capping where methane must be controlled before bentonite hydration. In base liner applications, the PE layer protects the bentonite from cation exchange by aggressive leachate. The bentonite layer provides self-sealing and re-healing.

Advantages:

  • Immediate gas barrier from day one: no methane migration during the hydration window
  • Ion exchange protection: PE coating shields bentonite from aggressive leachate chemistry
  • Reduces excavation and clay material requirements vs. compacted clay liner alternatives
Construction worker guiding a large Bentofix® roll being lifted on a construction site.

To the application:

Landfill engineering

Typical applications:

  • Tailings storage facility (TSF) base liner and side slope sealing with acidic process water
  • Heap leach pad liners for gold, copper and silver operations with aggressive chemical solutions
  • Mine water evaporation ponds and process water retention basins
  • Contaminated site encapsulation and brownfield development with chemical challenge

Bentofix® X is a coated GCL for mining and chemical containment environments. The PE coating is the first line of defence against acid rock drainage and saline brine, preventing cation exchange degradation of the bentonite. X5F achieves ≥ 9 kPa interface friction at 20 kPa (ASTM D6243); X10F achieves ≥ 15 kPa. This enables steeper slope designs and reduces facility footprint. Secugrid® geogrids can be combined with Bentofix® X for additional slope reinforcement.

Advantages:

  • Chemical resistance: PE layer is the primary barrier against acid rock drainage and brine solutions
  • Slope stability: X5F ≥ 9 kPa; X10F ≥ 15 kPa interface friction at 20 kPa (ASTM D6243)
  • Dual barrier system: PE + bentonite provides two independent containment layers per regulatory requirement
  • Self-sealing: if the PE layer is punctured, the bentonite layer re-seals on hydration
Aerial view of a large open-pit mining site where Bentofix® X was installed with terraced earthworks, lined containment areas, and a water pond.

To the application:

Mining

  • Hydraulic engineering and waterproofing

    • Pond, reservoir and canal liners requiring immediate barrier
    • Artificial lake sealing for high water quality requirements
    • Flood protection embankments with desiccation risk
    • Below-slab structural waterproofing

  • Radon and gas barriers

    • Building foundation sealing against radon ingress from soil
    • Passive radon protection for residential and public buildings below grade

  • Groundwater protection

    • Secondary containment for chemical and tank farm facilities
    • Retention basins for road runoff with de-icing salt exposure

  • Agriculture and biogas

    • Slurry lagoon and biogas plant base sealing (AwSV compliant)
    • JGS plant sealing where groundwater protection applies

Technical properties

PropertyUnitBentofix® X2 BFG 5300Bentofix® X5F BFG 5300
Cover layer
Geotextile type—Needle-punched nonwoven PPNeedle-punched nonwoven PP
Mass per unit areag/m²220220
Bentonite filling of cover NW (entire surface)g/m²800800
Bentonite layer (total, including nonwoven filling)
Bentonite type—Sodium bentonite powderSodium bentonite powder
Bentonite grain sizemm≤ 0.2≤ 0.2
Mass per unit area (at ≤ 15 % moisture content)g/m²4,9704,970
Swell indexml/2 g≥ 24≥ 24
Fluid lossml/2 g≤ 18≤ 18
Moisture content%1010
Carrier layer
Geotextile type—Slit-film woven PPSlit-film woven PP
Mass per unit areag/m²110110
Polyethylene coating (on carrier layer)
Surface—SmoothEmbossed, structured
Mass per unit areag/m²≥ 200≥ 500
Nod height of embossed surfacemm—≥ 0.4 (80 % of nods)
Interface shear stress vs 300 g/m² nonwoven at 20 kPakPa—≥ 9
Geosynthetic clay liner (including PE coating)
Mass per unit area (at ≤ 15 % moisture content)g/m²5,5505,850
Thickness, drymm6.06.3
Tensile strength, max., MDkN/m1422
Tensile strength, max., CMDkN/m1422
Elongation at maximum tensile force, MD%1010
Elongation at maximum tensile force, CMD%66
Peel strength, maximum peak valueN/10 cm≥ 60≥ 60
Peel strength, average valueN/m≥ 360≥ 360
Internal shear strength (24 h hydration, 20 kPa)kPa≥ 35≥ 35
Static puncture test (CBR)N2,5003,300
Permeability k₁₀ – PE coating without GCL (calculated)m/s≤ 10⁻¹⁴≤ 10⁻¹⁴
Permeability k₁₀ – GCL without PE coatingm/s1.5 · 10⁻¹¹1.5 · 10⁻¹¹
Permittivity ψ₁₀1/s1.5 · 10⁻⁹1.5 · 10⁻⁹
Index flux q₁₀ – GCL without PE coating(m³/m²)/s2.8 · 10⁻⁹2.8 · 10⁻⁹
Overlaps, quality assurance and delivery form
Overlapping areas, longitudinal and transverse—Self-sealingSelf-sealing
Overlaps and connections—Bentofix® X Tape B, one-sided self-adhesiveBentofix® X Tape B, one-sided self-adhesive
Needle detector tested—YesYes
Needle-punched fibres fully integrated in PE coating—YesYes
Roll widthm4.854.85
Roll lengthm4040
Roll aream²194194
Aerial view of a stormwater retention basin during construction, lined with PE-coated Bentofix® geosynthetic clay liner. An excavator and construction workers are installing the GCL across the basin floor and slopes.
Aerial view of a stormwater retention basin during construction, lined with PE-coated Bentofix® geosynthetic clay liner. An excavator and construction workers are installing the GCL across the basin floor and slopes.
Stormwater retention basin sealed with PE-coated Bentofix® GCL. The geosynthetic clay liner provides a combined bentonite and polymer barrier for reliable containment across the basin floor and slopes.
Stormwater retention basin sealed with PE-coated Bentofix® GCL. The geosynthetic clay liner provides a combined bentonite and polymer barrier for reliable containment across the basin floor and slopes.

PE-coated GCLs: why two independent barriers beat one at high head and chemicals

Bentofix® X is a multicomponent geosynthetic clay liner with two physically independent sealing barriers - addressing the two conditions under which standard GCLs fail on demanding projects.

First, the hydration window: sodium bentonite reaches k ≈ 1.0 x 10⁻¹¹ m/s only after hydrating, which takes days to weeks - and gas, radon, methane and vapour pass unimpeded until then. Bentofix® X has no such window; its PE layer achieves k ≤ 10⁻¹⁴ m/s from installation (EN 14150).

Second, cation exchange: in calcium-rich environments - landfill leachate, saline groundwater, mine process water - Ca²⁺ and Mg²⁺ replace Na⁺ in the bentonite, raising hydraulic conductivity by one to two orders of magnitude. The PE layer physically separates the bentonite from the aggressive liquid, preventing contact and ion exchange.

Both barriers act in series: as the bentonite hydrates, it locks the PE layer in compression, increasing resistance to hydraulic gradients. For slopes, X5F structured PE (500 g/m², 0.4 mm nod height at 80 %) achieves ≥ 9 kPa shear stress against 300 g/m² Secutex® nonwoven at 20 kPa (ASTM D6243); X10F heavy structured PE (1,000 g/m², 0.9 mm) reaches ≥ 15 kPa for maximum friction on steep embankments.

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Bentofix® X geosynthetic clay liner projects: sealing case studies

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Frequently asked questions

Bentofix® X is a multicomponent geosynthetic clay liner (GCL) and geosynthetic clay barrier (GBR-C) from Naue. It combines a sodium bentonite core needle-punched between PP geotextile layers with an extrusion-coated PE layer permanently bonded to the woven carrier. The PE layer provides an immediate hydraulic and gas barrier (k ≤ 10⁻¹⁴ m/s, EN 14150) from installation. The bentonite core self-seals on hydration and provides the long-term sealing function. Together: two independent barriers in one product.

Naue does not publish standard list prices for Bentofix® X products. Pricing depends on project volume, variant (X2, X5F, X10F), type (BFG, NSP), and project location. Request a project-specific quote via the contact form below or contact info@naue.com. For large containment and landfill projects, Naue provides full project engineering support including quantity optimisation.

Both are geosynthetic clay liners with sodium bentonite core and PP geotextile layers. Bentofix® X adds an extrusion-coated PE layer to the woven carrier side. This PE layer provides three advantages:

  1. immediate gas and vapour barrier from installation,
  2. ion exchange protection for the bentonite in aggressive environments, and
  3. higher interface friction for slope applications (X5F/X10F). Where standard Bentofix® meets design requirements, it remains the cost-effective option.

X2 has a smooth PE coating (200 g/m²). Use for waterproofing, pond liners, below-slab applications and flat installations where slope friction is not critical. X5F has a structured PE coating (500 g/m², 0.4 mm nod height) providing ≥ 9 kPa interface friction at 20 kPa (ASTM D6243). Use for landfill side slopes and embankments requiring higher friction angles. X10F has a heavy structured PE (1,000 g/m², 0.9 mm nod height) providing ≥ 15 kPa interface friction: for the steepest slopes. All three variants are available in BFG 5300 and NSP 4000/4900 types.

A single low-permeability barrier can be compromised by ion exchange in aggressive leachate. In landfill and mining applications, calcium and magnesium ions replace sodium in the bentonite, increasing its hydraulic conductivity over time. The PE layer in Bentofix® X prevents contact between the aggressive liquid and the bentonite, maintaining barrier integrity throughout the design life. The bentonite layer provides self-sealing if the PE layer is damaged.

One square metre of Bentofix® X (~10 mm installed thickness) replaces up to 600 mm of compacted clay liner. This reduces excavation volumes, clay import tonnage, and transport movements significantly. The PE coating also reduces the cover soil depth required for desiccation protection compared to standard GCL.

Bentofix® X carries CE marking, is produced under ISO 9001 and DIN 18200 third-party monitoring. Bentofix® X2 BFG 5300 holds BBA-HAPAS certificate no. 05/4256 for waterproofing system use in the UK. ÖNORM covers X6F NSP 5300 ÖN and X10F NSP 5300 ÖN for Austrian applications. An EPD covers the Bentofix® product family.

The Thermal Lock process integrates fibres into the PE coating, preventing delamination during handling and soil placement. Every roll is needle-detector tested across its full width before dispatch. Tensile strength: 16/16 kN/m md/cmd (X2, EN ISO 10319) and 22/22 kN/m (X5F BFG 5300). X10F NSP 4900: 25/25 kN/m. Static puncture (CBR): 2,800 N (X2/X5F) and 4,000 N (X10F NSP 4900)

All Bentofix® X variants have a roll width of 4.85 m and a roll length of 40 m, giving 194 m² per roll. This applies to BFG 5300 and all NSP types (4000 and 4900). The 30 cm overlap zone is pre-marked on the PE surface of every roll.

CE marking, DIN 18200 third-party monitoring, ISO 9001. Testing per: EN ISO 10319 (tensile strength), EN ISO 12957-1 (internal shear strength), ASTM D6496 (peel strength), EN 16416 / ASTM D5887 (GCL hydraulic conductivity), EN 14150 (PE layer hydraulic conductivity). BBA-HAPAS certificate no. 05/4256 applies for UK use of X2 BFG 5300. ÖNORM for Austrian variants.

Yes. Naue provides engineering support including slope stability calculations, liner system design, specification preparation and installation supervision. The Naue Platform (PortalCalc) offers online tools for quantity take-off and system comparison. Contact info@naue.com or submit a project request via the contact form below.

Yes. The PE layer in Bentofix® X provides an immediate gas-tight barrier effective against radon (Rn-222) from soil. Unlike standard GCLs, Bentofix® X does not require bentonite hydration before achieving gas impermeability. Suitable for below-slab radon protection in residential and commercial buildings. Bentofix® X2 BFG 5300 holds BBA-HAPAS certificate no. 05/4256 for waterproofing applications in the UK.

The PE layer creates a continuous hydraulic and gas barrier across each GCL panel. At overlap zones, the PE surfaces of adjacent panels must be bonded to maintain this continuous barrier. Bentofix® X Tape B is a one-sided self-adhesive tape designed for PE-to-PE bonding. Without it, the PE barrier is interrupted at seams. On BFG types, bentonite impregnation provides additional overlap sealing. The overlap zone (30 cm) is pre-marked on the PE surface of every roll.

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