Film-coated Sodium Bentonite Waterproof Blanket (GCL)

What Is a Film-Coated Sodium Bentonite Waterproof Blanket (GCL)？

A film-coated sodium bentonite waterproof blanket, also known as a GCL (Geosynthetic Clay Liner), is a composite waterproofing material made by placing natural sodium bentonite between two geotextiles, then adding a polyethylene (PE) film layer on the surface. The film enhances impermeability and provides extra protection against puncture, moisture loss, and chemical attack.

When hydrated, the bentonite swells and forms a low-permeability gel layer, while the film barrier adds an additional waterproofing layer. This product is widely used in tunnels, basements, landfills, artificial lakes, and underground structures where high waterproofing performance is critical.

Key Technical Specifications:

• Bentonite Content: ≥ 5.0 kg/m²

• Swelling Index: ≥ 24 mL/2g

• Permeability: ≤ 5.0 × 10⁻¹¹ m/s

• Film Type: PE (Polyethylene), single or double-sided

• Thickness: Typically 6–10 mm

Applications of Film-coated Bentonite Waterproof Blankets

The film-coated sodium bentonite GCL is a reliable solution for a wide range of waterproofing and containment projects, including:

Municipal Landfills & Solid Waste Disposal Sites
Prevents leachate and hazardous waste from contaminating surrounding soil and groundwater.

Underground Tunnels, Subways & Basements
Provides long-term waterproof protection for below-grade concrete structures.

Artificial Lakes, Ponds & Aquaculture Pits
Maintains water retention with excellent anti-seepage performance.

Oil & Chemical Storage Facilities
Acts as a secondary containment layer, preventing penetration of hydrocarbons and corrosive liquids.

Mining Tailings & Industrial Waste Pools
Ensures environmental safety by creating a durable, chemical-resistant sealing layer.

The film-coated sodium bentonite waterproof blanket combines the natural sealing ability of bentonite with the mechanical strength of geotextiles and the impermeability of PE film, making it an ideal geosynthetic solution for demanding waterproofing environments.

 

The sodium-based bentonite core layer and the coating work together to form a dense gel-like barrier layer when exposed to water, achieving seamless sealing protection between the soil and the structure. The core layer expands when exposed to water and automatically fills the cracks, continuously repairing the leakage path caused by construction damage or foundation deformation, and ensuring long-term anti-seepage reliability.

 

The coating layer enhances tear resistance, effectively resists damage such as backfill gravel and root puncture, and maintains the structural integrity of the waterproof system. The roll material is flexible and easy to lay, and can adapt to special-shaped base surfaces; natural bentonite materials are non-toxic and harmless, which meets the environmental protection needs of green engineering.