Bentofix® geosynthetic clay liners (GCL) are a shining example of how geosynthetics perform best: by interacting with natural elements to create something stronger.

Bentofix® is renowned for its high performance in challenging environments, and with the addition of Bentofix® X Coating, you can access a range of enhanced benefits including better desiccation protection, enhanced shear strength and increased chemical resistance.

What is Bentofix®?

Bentofix® is a geosynthetic clay liner or GCL. Also known as a geosynthetic clay barrier, this versatile geotextile is made from needle-punched, reinforced composites that combine two durable geotextile outer layers and a uniform core of high-swelling powdered bentonite clay.

Needle punched geotextile technology

The needle-punched manufacturing technology of this GCL increases its internal and external shear strength, which in turn creates an expanded range of applications in which it can be used. The needle-punching process firmly bonds the three layers of Bentofix® by sandwiching a core of sodium bentonite between two outer encapsulating geotextiles. This bond creates a single, engineered barrier that utilises the best of both synthetic and natural materials.

The Power of Powdered Bentonite Clay

Bentofix® GCLs consistently outperform traditional barrier methods that use thick layers of compacted clay. The immediate swelling characteristic of powdered bentonite provides a long-term barrier that can self-heal and reseal itself, filling punctured or damaged areas. This feature means the geotextile can be rehydrated and renewed, even if it has been exposed to desiccation.

Long term protection against piping

The formation of channels in clay-based material is often referred to as piping. This settling and movement of the material can lead to erosion and redistribution of material, creating a less effective barrier. This is why Bentofix® GCL has been specifically engineered to protect piping, as well as durability to resist damage and strength to manage the challenges inherent in barrier designs.

Bentofix® X Coating: the add-on value

Bentofix® geosynthetic clay liner is available with a unique polyethylene coating component known as Bentofix® X.

The Bentofix® X polyethylene extrusion coating ensures an immediate and enhanced barrier to gas and radon while protecting against desiccation and critical substances. In applications with high hydraulic gradients over coarse soils, the additional Bentofix® X coating prevents bentonite piping. In other applications, it acts as a possible root barrier. The polyethylene coating is uniformly applied to the woven component, creating a durable bond with the needle-punched fibres. This ensures a very high fibre pull-out resistance and increases the long-term internal shear strength.

3. Advantages of choosing Bentofix® X

a. Better desiccation protection

Bentofix® X GCLs are coated with a polyethylene layer on the slit-film woven side. Installed with this coating facing up, the GCL’s performance against desiccation improves.

In a field test, Bentofix® X was placed over a sand layer with the PE coating facing up. Bentofix® X was saturated for 3 weeks with water through the sand layer under a confining stress of 18kN/m² prior to the desiccation period at a temperature of 40°C and air humidity of 40%.

During a period of 250 days, the moisture content of the bentonite layer was monitored. The results show that a relative water loss of less than 10% occurred, providing strong evidence that Bentofix® X will not desiccate under these conditions.

b. Enhanced shear strength

The interface friction angle also plays a major role in slope applications. The mechanically bonded nonwoven material of Bentofix® provides high interface friction angles. However, the polyethylene coating of Bentofix® X can vary according to the thickness of the coating, therefore, project-specific friction angles should be specified.

For slope inclinations up to 2.5:1 (h:v), the extruded friction structure of Bentofix® X is typically suitable.

c. Better chemical resistance

The polyethylene coating of Bentofix® X is manufactured from high-quality resins, which are comparable to those used in certified geomembranes. This gives the coating the necessary chemical resistance for long-term bentonite protection against critical substances.

Features and benefits of Bentofix® X

• A versatile solution for a range of sealing applications

• Immediate sealing and long-term performance with high-swelling sodium bentonite powder and durable PE coating

• Desiccation barrier

• Protection against ion exchange

• Barrier against roots

• Gas and radon barrier

• Improves the protection against bentonite erosion from high water pressures and gravelly subsoils

• Direct coverage with concrete and lime is possible

• Shear resistant overlapping is possible with special adhesive tapes

• Cost-saving alternative to compacted clay

• Robust and durable geosynthetics encapsulate the bentonite sealing core

• The uniform needle-punching improves multi-directional shear strength and internal friction angle

• Self-sealing length overlaps; with BFG types all overlaps self-seal

• Quick, easy and cost-efficient installation

Contact Global Synthetics for technical data on Bentofix® X

The Global Synthetics engineering team can provide spec sheets on both regular Bentofix® and Bentofix® X coatings, as well as providing advice for your specific application.