BENTOMAT Geosynthetic Clay Liners

Geosynthetic clay liners, also known as bentonite mats, are geosynthetic materials that have been in use for many years as a successful natural method for sealing against liquids and gases in a wide variety of applications. The spectrum ranges from landfill sites and road construction through to water engineering structures and the construction of storage and rainwater retention basins. In contrast to the construction method that uses mineral sealing materials such as clay, bentonite mats provide consistently high product quality and clear economic benefits.

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Your advantages

Excellent sealing

Full-coverage needle-punching

Self-repairing effect

Cost-effective sealing system

General

BENTOMAT Geosynthetic Clay Liners normally consist of three components: The geotextile top layer, the bentonite granules and the geotextile base layer.

As a rule, the geotextiles consist of a mechanically-bonded, non-woven fabric on one side and a woven geotextile on the other side. All the components of the layers are mechanically bonded by needle-punching over their entire area and are filled uniformly with bentonite granules.

This ensures that the bentonite is optimally embedded and prevents material loss and rearrangement during transport and installation. The use of bentonite granules instead of the conventional bentonite powder avoids the problem of dust production.

The main component of BENTOMAT is the mineral sodium bentonite, which is 90 % montmorillonite. Bentonite is a volcanic clay mineral that formed naturally during the course of 200 million years under the influence of water and pressure.

Only high quality bentonite in granular form is used for the manufacture of BENTOMAT Geosynthetic Clay Liners. The excellent swelling capacity of bentonite when it comes into contact with moisture is responsible for the quick and reliable sealing effect of the BENTOMAT.

This special property of bentonite allows the sealing layer to repair itself securely if it becomes mechanically damaged during installation or later use.

When dimensioned correctly, BENTOMAT Geosynthetic Clay Liners can also be laid on slopes. The mechanical needle-punching of the components across the entire area of the liner creates a firm bond and a high internal shear angle.

Bentomat GDA CL

BENTOMAT GDA CL is the perfect solution when it comes to greater depths of standing water, because the flow through geosynthetic clay liners increases at higher hydraulic gradients. By adding an PE membrane, this effect is significantly impeded without having to forgo the benefits of a bentonite mat.

BENTOMAT GDA CL is the ideal solution for applications where the hydraulic performance of traditional geosynthetic clay liners is inadequate and a conventional combination sealing system would be uneconomical. The PE membrane used as standard is 1.50 mm thick and has a textured surface. Membranes with a thickness from 0.20 mm up to 1.50 mm are also available.

For thicknesses greater than 1.50 mm, the membranes can also be welded together by a professional installer in order to achieve the best possible seal.

As a composite made of mineral sealing material with a sealing geomembrane bonded to it, BENTOMAT GDA CL is a multi-layer product that offers the highest level of reliability.

BENTOMAT cross-section

PP fibres (needle punched from the non-woven fabric side)
PP woven geotextile
Bentonite granules
PP non-woven fabric

BENTOMAT Geosynthetic Clay Liners normally consist of three components: The geotextile top layer, the bentonite granules and the geotextile base layer.

BENTOMAT GDA CL cross-section

PE-Membran
PP woven geotextile
Bentonite granules
PP non-woven fabric

BENTOMAT GDA CL has been specially developed for applications with particularly stringent requirements in terms of sealing performance. This innovative product incorporates an HDPE membrane that is bonded across the whole area of the bentonite mat to create a multi-layer product. The bonded membrane provides additional protection against unwanted drying out and against root penetration.

Functions

Sealing

As a sealing element, BENTOMAT Geosynthetic Clay Liners protect the environment, structures and people from the harmful effects of liquids and gases. This is particularly true in the case of landfill sites and road, tunnel and water engineering construction.

Die Dichtungseigenschaft von BENTOMAT Tondichtungsbahnen wird wesentlich vom verwendeten Bentonit bestimmt. Die hohe Dichtwirkung von BENTOMAT ergibt sich durch die Begrenzung des natürlichen Quellverhaltens des Bentonits unter Wasseraufnahme.

Die Filamente des Trägervliesstoffes verfestigen BENTOMAT bei der vollflächigen Vernadelung gleichmäßig und setzen in Kombination mit der dauerhaften Auflast aus geeignetem Deckmaterial der natürlichen Quellneigung enge Grenzen.

Self-repairing effect

A side effect of the swelling capacity of bentonite is that if minor mechanical damage is caused to the liner, a so-called “self-repairing effect” comes into play, whereby the leaking area seals itself automatically. The swelling pressure “repairs” damaged areas up to 6 mm in diameter.

As is also the case with purely mineral liners, geosynthetic clay liners are not completely watertight and gas-tight. However, they can achieve the same sealing effect with a significantly thinner liner.

Applications

Infrastructure projects

The types of application for geosynthetic clay liners in road and traffic route construction are far ranging. They are used for the protection of groundwater in and around traffic areas to prevent the harmful effects caused by the ingress of substances that are hazardous to water.

Retention basins are constructed for the purpose of delaying the discharge of surface water and protecting the groundwater. Here, BENTOMAT Geosynthetic Clay Liners can replace mineral sealing materials.

Bei Maßnahmen für den Grundwasserschutz sind für Bentonitmatten die Nachweise entsprechend den Richtlinien für bautechnische Maßnahmen an Straßen in Wassergewinnungsgebieten (RiStWag) zu erbringen.

Groundwater protection in traffic areas

BEMAT Erosion Control Mat, if required
BEGRID Flex Geogrid for slopes > 25°, if required
BENTOMAT Geosynthetic Clay Liner

Multi-storey and underground car parks

Concrete block paving
40 – 60 mm gravel
At least 300 mm combined frost protection and sub-base layer 0/45
BETEX TP Non-woven Protection Fabric
BENTOMAT Geosynthetic Clay Liner
Base layer

Dykes and water engineering structures

One of the classical fields of application for geosynthetic clay liners is in dykes and water engineering structures. Here, bentonite mats are used to prevent water losses, to separate ground water from surface water and to ensure durability and erosion stability and thus the static stability of structures. Water engineering structures that require sealing include for example storage basins, ponds, dams, dykes and canals. The selection of a geosynthetic clay liner for use as a sealing element in water engineering structures is made in accordance with the project-specific requirements.

Dyke sealing

Dyke path
BETEX TP Non-woven Protection Fabric
Crown
Assumed flood level
BEGRID Flex Geogrid
BENTOMAT Geosynthetic Clay Liner

Rainwater retention basin

Embedding trench
Fill material
BEMAT Erosion Control Mat, if required
BEGRID Flex Geogrid, if required
BENTOMAT Geosynthetic Clay Liner

Fire water pond or reservoir

BENTOMAT GDA CL Geosynthetic Clay Liner
BETEX TP Non-woven Protection Fabric
Mortar
Concrete
Block paving

Landfill sites

In order to avoid the risk of environmental hazards, waste material in landfill sites and waste disposal facilities must be stored permanently and safely. The relevant technical regulations specify suitable systems for sealing the base and upper surface of landfill sites. Geosynthetic clay liners are used in surface sealing systems, in the technical barrier, and in intermediate and temporary sealing layers.

The selection of a geosynthetic clay liner for use as a sealing element in a landfill site is made in accordance with the project-specific suitability assessment made by the relevant waste management authority. This certification of suitability is important because the clay liner forms an essential component in a coordinated sealing system. The certification of suitability is deemed to have been successfully completed if a nationally recognised suitability approval has been issued by the German states (LAGA Ad-hoc-AG “Deponietechnik”) for a sealing component or a sealing system.

The BENTOMAT LAGA Geosynthetic Clay Liner has been issued with a LAGA suitability approval for the construction of mineral sealing layers in surface sealing systems for landfill classes 1 and 2.

Landfill class 1

Recultivation layer
Drainage membrane with BAM (German Materials Research and Testing Institute) approval
BENTOMAT Geosynthetic Clay Liner
Regulating course
Geotextile as a separating layer
Waste

Landfill class 2

Recultivation layer
Drainage membrane with BAM (German Materials Research and Testing Institute) approval
PE synthetic geomembrane with BAM (German Materials Research and Testing Institute) approval
BENTOMAT Geosynthetic Clay Liner
Regulating course
Geotextile as a separating layer
Waste

Contaminated sites

The remediation of contaminated sites involves the construction of technical systems that are suitable for protecting the soil, groundwater and bodies of water in the long term.

Contaminated areas are permanently and safely encapsulated with sealing systems comprising various coordinated components. This dispenses with the need for costly treatment or decontamination measures.

The aim is to achieve emission-free storage of soils and building materials that contain environmentally harmful substances. The ingress of rainwater is reduced and leaching from these soils and building materials is prevented.

Construction method with weather-sensitive sealing element and no seepage layer

Fill material
BEDRAIN Drainage Mat
BENTOMAT Geosynthetic Clay Liner

Construction method with weather-sensitive sealing element and a drainage layer

Fill material
BEDRAIN Drainage Mat
BENTOMAT GDA CL Geosynthetic Clay Liner

Data

Properties	GDA	LAGA	300/200	GDA CL*
Product type	All-over needle-punched clay liner			All-over needle-punched clay liner with additional sealing membrane
Raw material	Non-woven: PP. Inlay: Bentonite. Woven: PP			Non-woven: PP. Inlay: Bentonite. Woven: PP. Membrane: PE
RiStWag Sealings	yes	yes	yes	yes
LAGA appraisal of aptitude		yes
Areas of application
Landfill sites		●
Contaminated sites	○	●	○	●
Dike and hydraulic structures	○	●	○	●
Retention basins	○	●	●	●
Reservoirs**	○	○	○	●
Road and traffic areas	●	●	●	○
Canal structures	●	●	●	○
Ponds**	○	○	○	●
Underground / multi-storey car parks	○	●	●	○

● suitable | ○ partly suitable (project-related assessment necessary)

Special types available on request. | *0,2 – 1,5 mm. Available with or without structure | ** Depending on the product-specific water permeability, overflow height, physical soil and climatic conditions, a controlled water supply may be necessary.

Request further product information

Savings

POTENTIAL SAVINGS thanks to BENTOMAT Geosynthetic Clay Liners

With mineral clay sealing layers, layer thicknesses of up to 100 cm are required. BENTOMAT achieves a comparable or superior sealing effect with a thickness of just 1 cm.

As well as conserving natural raw materials and reducing excavation, the thinner BENTOMAT Geosynthetic Clay Liners also allow comparatively larger volumes of waste to be deposited in landfill sites.

The use of bentonite mats is therefore more environmentally friendly and more cost-effective than the conventional method of construction.

Because BENTOMAT is industrially manufactured and is therefore subject to continuous quality monitoring, it guarantees a sealing layer that has constant and uniform properties.

Replaces mineral clay sealing liners that are up to 100 cm thick

Installation

BENTOMAT Geosynthetic Clay Liners are quick and easy to install. BENTOMAT is supplied in rolls and laid with an overlap, requiring no expensive welding work. The required overlap width of 30 cm is marked on the mat during manufacture. In order to achieve the same sealing effect in the overlap area as in the rest of the liner, a layer of loose bentonite granulate is strewn, on site, in the marked overlap area. In order to maximise the sealing performance, bentonite mats require permanent loading with a suitable fill material laid in a layer at least 30 cm thick.

Lifting equipment that has a cross beam and is suitable for lifting loads of at least 1300 kg is required for unloading and laying the liners. The rolls, even if still packaged, must be stored in dry and weatherproof conditions.
The material may be laid only by qualified personnel.
It must always be laid in dry weather.
The subgrade must be flat, even and free of foreign bodies, surface water, rubble, roots, and pointed or sharp edged stones.
The liners must always be laid without creasing and in the direction of incline.
The overlap areas must be installed neatly and with particular care.

The bentonite granules must be distributed evenly in the overlap areas.
For reasons of stability, it may be necessary to secure the bentonite mat at the top edge of the incline.
Extra care must be taken in the area of pipe penetrations and connections.
To prevent the material from swelling before the overburden is applied, it must be covered with suitable fill material immediately after laying.
The covering material must be “end tipped” onto the liner.
Vehicles must not drive directly on the liner.
In order to achieve the required overburden, the entire surface of the BENTOMAT liner must be covered with fill material.

Our detailed installation and laying instructions for BENTOMAT Geosynthetic Clay Liners must also be observed.

Advantages

Excellent sealing performance
Self-repairing effect
Full-coverage needle-punching
Consistent product characteristics
Many areas of application
Very little dust generation during installation
Conserves natural resources
Cost-effective sealing system
Cost-effective installation
Low transport costs

Additional advantages of the BENTOMAT GDA CL Geosynthetic Clay Liners

Redundant sealing system to meet the highest safety and reliability requirements
Superior sealing performance compared to conventional clay liners
Root-proof sealing
Drying out is effectively prevented