GCL
Geosynthetic clay liner. Sodium bentonite needle-punched between two geotextiles, sealing on contact with water and closing small punctures by itself.
A barrier that repairs its own small damage
A GCL is a compacted clay liner delivered as a roll. The bentonite core swells on contact with water to many times its dry volume, and in doing so it seals the fabric into a barrier with permeability comparable to a metre of compacted clay, in about ten millimetres.
The swelling also means minor punctures close themselves, which no geomembrane does. That self-healing behaviour is the whole reason a GCL is specified under or alongside a membrane in critical containment rather than instead of one.
- High-swelling powder sodium bentonite core, not granular fill.
- Needle-punched reinforcement for internal shear strength.
- Overlap seams only, with bentonite paste at the joints.
GCL configurations we supply
The fabric faces are chosen by what the liner sits between and how steep the slope is.
Standard needle-punched GCL
Bentonite core between a woven and a nonwoven geotextile, needle-punched through. The general-purpose build for base lining and containment on shallow gradients.
- Woven and nonwoven faces
- Base lining and containment
- 4000 to 6500 GSM
Reinforced GCL for slopes
Heavier needle-punching and a nonwoven face on both sides, raising internal shear strength and interface friction for steeper gradients and cap systems.
- Higher internal shear strength
- Steep slopes and capping
- Improved interface friction
What the bentonite core does
Features
- Uniformly distributed high-swelling powder sodium bentonite.
- Two durable geotextile layers encapsulating the core.
- Uniform needle-punching across the full panel.
- Mass per unit area from 4000 GSM to 6500 GSM.
- Standard width 5 m, lengths 15 m to 50 m, both customisable.
- Overlap jointing, no welding equipment required.
Advantages
- Seals immediately on hydration and keeps sealing long term.
- Self-heals minor punctures, which a geomembrane cannot do.
- Replaces roughly a metre of compacted clay in about ten millimetres.
- Quick, simple and low-cost to install with no specialist plant.
- Needle-punching gives multi-directional internal shear strength.
- Tolerates freeze-thaw and wet-dry cycling without losing performance.
GCL ordering information
Standard production. Slope angle drives the reinforcement level, so send us the gradients with the enquiry.
Product
Needle-punched geosynthetic clay liner
Core
High-swelling powder sodium bentonite
Facings
Woven and nonwoven geotextile
Mass per unit area
4000 GSM to 6500 GSM
Width
5 m standard, customisable
Roll length
15 m to 50 m, customisable
Jointing
Overlap with bentonite paste at seams
Minimum order
By project, quoted on drawings
Packing
Wrapped rolls on pallets
Delivery terms
EXW, FOB, CFR, CPT
Where GCL is installed
Critical containment where a single barrier is not enough, and waterproofing where a welded membrane would be impractical.
- Landfill caps and base lining systems
- Environmental protection under infrastructure
- Dams, canals and water containment
- Secondary containment bunds
- Basement and foundation waterproofing
- Mining containment and process ponds
- Tunnel sealing systems
- Groundwater protection barriers
Specifying a composite barrier?
Send us the slope angles, the head of liquid and whether the GCL sits under a geomembrane. We will confirm the mass per unit area and the reinforcement.