Geocomposites combine two or more geosynthetics in a single piece to solve problems that a single material could not: draining and filtering simultaneously, or waterproofing with self-sealing capacity. The choice between a drainage geocomposite and a geosynthetic clay liner (GCL) is not a matter of nuance: one lets water through in a controlled way, the other blocks it. This comparison of the two MOLTEXO geocomposites helps you decide which one fits your project.
🎯 Choose in 10 seconds
- If you need to drain water from the subsoil or the back of a wall without clogging, in walls, basements, green roofs or foundations: go to Drainage geocomposite
- If you need to waterproof landfill bottoms, ponds or reservoirs with auditable environmental criteria: go to Geosynthetic clay liner (GCL)
What to consider before choosing
Before buying, assess these four criteria. They determine whether the geocomposite fulfills its function or fails at the project's first watertightness or drainage test.
- Hydraulic function of the project: drainage (evacuating water toward an outlet point) and waterproofing (preventing the passage of water) are opposite functions. Applying a drainage product where watertightness is needed produces leakage; applying GCL where drainage is needed produces accumulated hydrostatic pressure and structural damage.
- Type of project and overhead load: retaining walls and green roofs call for a drainage product with mechanical strength calibrated to support the backfill. Landfills, ponds and reservoirs call for GCL with sodium bentonite that hydrates and self-seals. Each material is sized for its scenario.
- Self-sealing capacity and damage tolerance: the GCL self-seals if it suffers a small puncture, thanks to the expansion of the bentonite; the drainage geocomposite does not self-seal, but as a drainage product it does not need watertightness. The filtration of the drainage product is maintained for years thanks to the quality of the lateral geotextiles against clogging.
- Environmental criteria and contractual audit: projects with the ISO 14001 environmental standard or a contractual audit require GCL with sodium bentonite of controlled origin and calibrated geotextiles. For drainage in a residential wall, a drainage geocomposite with a geonet core between two geotextiles is sufficient.
Drainage geocomposite: high-flow planar drainage
- 3D geonet core between two filtering geotextiles
- Replaces drainage gravel: saves excavation, weight and logistics
- Integrated filtration against clogging for decades
- Double-sided with geotextile: installation without specific orientation
- 5.8 m × 100 m roll, manageable with basic equipment
- Does not waterproof (drainage function, not watertight)
- Requires a well-designed water outlet in the system
Drainage geocomposite roll (geodrain) in non-woven geotextile + geonet + non-woven geotextile format, width 5.8 m (19 ft) and length 100 m (328 ft). Three-dimensional geonet core with high planar flow capacity and filtering lateral geotextiles against clogging. Designed for vertical drainage behind retaining walls and basement walls to relieve hydrostatic pressure; horizontal drainage under foundation slabs; green roofs to evacuate excess irrigation and rainwater; sanitary landfills, tunnels and underground works with professional perimeter drainage.
Geosynthetic clay liner (GCL): auditable waterproofing
- Sodium bentonite between two needle-punched geotextiles
- Ultra-low permeability when hydrated (10-15× expansion)
- Self-sealing against small punctures through expansion
- Adapts to terrain irregularities without welding
- Natural bentonite with no synthetic chemicals (environmental criteria)
- Does not drain (watertight function, does not allow water passage)
- Requires protection until hydrated and sealed
Geosynthetic clay liner roll (GCL) with a sodium bentonite core between two layers of needle-punched geotextile, width 5.8 m (19 ft) and length 40 m (131 ft). Designed for waterproofing of bottoms in sanitary landfills and landfill cells with the ISO 14001 standard or equivalent; oxidation ponds, water treatment plants and industrial reservoirs with watertightness criteria; leaching cells in mining and containment of chemical solutions; artificial lakes, agricultural reservoirs and landscaping works with bodies of water that require waterproofing.
Comparison table
| Feature | Drainage geocomposite | GCL (clay liner) |
|---|---|---|
| Hydraulic function | Planar drainage | Waterproofing |
| Composition | Geotextile + 3D geonet + geotextile | Geotextile + sodium bentonite + geotextile |
| Permeability | High (drains water) | Ultra-low (watertight) |
| Self-sealing against punctures | — | Yes (bentonite expansion) |
| Typical application | Walls, basements, green roofs, foundations | Landfills, ponds, reservoirs |
| Roll width | 5.8 m (19 ft) | 5.8 m (19 ft) |
| Roll length | 100 m (328 ft) | 40 m (131 ft) |
| Brand | MOLTEXO | MOLTEXO |
Use case → recommended product matrix
| If your case is… | Recommended product |
|---|---|
| Drainage behind a retaining wall or basement wall | → Drainage geocomposite |
| Horizontal drainage under a foundation slab with subsoil moisture | → Drainage geocomposite |
| Residential green roof with irrigation and rain requiring drainage | → Drainage geocomposite |
| Sanitary landfill with perimeter drainage in the system | → Drainage geocomposite |
| Foundation on soil with high subsoil moisture | → Drainage geocomposite |
| Sanitary landfill bottom with ISO 14001 environmental audit | → GCL |
| Oxidation pond or water treatment plant | → GCL |
| Leaching cell in mining or chemical containment | → GCL |
| Agricultural reservoir or artificial lake with watertightness criteria | → GCL |
| Industrial reservoir on irregular terrain with curves and slopes | → GCL |
Before buying, define two facts: whether the water must pass through (drain) or stop (be retained), and whether the project has an environmental audit. The practical rule: drainage behind a wall or under a slab → drainage geocomposite; waterproofing of a landfill bottom, pond or reservoir → GCL. Combining functions is possible: in some landfills GCL is used as the primary barrier with a drainage geocomposite on top to evacuate leachate. Consult the project's engineering design before deciding.
Do not use a drainage geocomposite where watertightness is needed. The drainage function implies high permeability — water passes through the material by design. For landfills, ponds, reservoirs and hydraulic works with environmental criteria, the only correct option is GCL or HDPE geomembrane. Conversely: applying GCL where drainage is needed produces accumulated hydrostatic pressure that damages structures and saturates the soil.
All compared products
Frequently asked questions
Can I combine a drainage geocomposite and GCL in the same project?
Yes. In sanitary landfills and ponds, GCL is used as the primary waterproofing barrier with a drainage geocomposite on top to evacuate leachate or percolated water in a controlled way. Each material fulfills its function: GCL seals, the drainage product evacuates. The project's engineering design defines the exact combination.
Does the bentonite in the GCL remain active over time?
Yes. Once hydrated, sodium bentonite remains stable for decades under standard operating conditions. The self-sealing capacity is maintained as long as water is available to keep it hydrated, and the confining geotextiles prevent granule migration.
Does the drainage geocomposite completely replace drainage gravel?
In most applications yes, with significant savings in excavation volume, weight on structures and transport costs. For massive drainage works (large landfills with extreme loads), it is still combined with gravel or perforated pipe in the complete system, according to the engineering design.
