Geocomposites combine two or more geosynthetics into a single piece to solve problems that a single material could not: simultaneously drain and filter, or waterproof with self-sealing capability. The choice between a drainage geocomposite and a geosynthetic clay liner (GCL) is not subtle: one allows water to pass in a controlled manner, the other blocks it. This comparison of two MOLTEXO geocomposites will help you decide which one fits your project.
🎯 Choose in 10 seconds
- If you need to drain water from subsoil or wall backfill without clogging, in walls, basements, green roofs, or foundations: go to Drainage geocomposite
- If you need to waterproof landfill bases, ponds, or reservoirs with auditable environmental criteria: go to Geosynthetic clay liner (GCL)
What to consider before choosing
Before purchasing, evaluate these four criteria. They define whether the geocomposite fulfills its function or fails at the first leak test or project drainage test.
- Project hydraulic function: drainage (evacuating water to an outlet point) or waterproofing (preventing water passage) are opposite functions. Applying a drainage composite where watertightness is needed leads to leakage; applying a GCL where drainage is needed leads to accumulated hydrostatic pressure and structural damage.
- Type of work and overhead load: retaining walls and green roofs require a drainage composite with calibrated mechanical resistance to support the backfill. Landfills, lagoons, and reservoirs require GCL with sodium bentonite that hydrates and self-seals. Each material is dimensioned for its specific scenario.
- Self-sealing capacity and damage tolerance: GCL self-seals if it suffers a small perforation due to bentonite expansion; the drainage geocomposite does not self-seal, but as it is for drainage, it does not require watertightness. The drainage composite's filtration is maintained for years due to the quality of the side geotextiles against clogging.
- Environmental criteria and contractual audit: projects with ISO 14001 environmental standards or contractual audits require GCL with controlled-origin sodium bentonite and calibrated geotextiles. For drainage in residential walls, 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 anti-clogging filtration for decades
- Double-sided with geotextile: installation without specific orientation
- 5.8 m × 100 m roll manageable with basic equipment
- Does not waterproof (draining 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, 5.8 m (19 ft) wide and 100 m (328 ft) long. Three-dimensional geonet core with high planar flow capacity and side filtering geotextiles against clogging. Designed for vertical drainage behind retaining walls and basement walls for hydrostatic pressure relief; 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 perforations due to expansion
- Adaptation to ground irregularities without welding
- Natural bentonite without synthetic chemicals (environmental criteria)
- Does not drain (watertight function, does not allow water passage)
- Requires protection until hydrated and sealed
Geosynthetic clay liner (GCL) roll with a sodium bentonite core between two layers of needle-punched geotextile, 5.8 m (19 ft) wide and 40 m (131 ft) long. Designed for waterproofing bases in sanitary landfills and fill cells with ISO 14001 standards or equivalent; oxidation ponds, wastewater treatment plants, and industrial reservoirs requiring watertightness; leachate cells in mining and chemical containment; artificial lakes, agricultural reservoirs, and landscaping projects with water bodies requiring waterproofing.
Comparative table
| Characteristic | Drainage Geocomposite | GCL (Clay Barrier) |
|---|---|---|
| Hydraulic function | Planar drainage | Waterproofing |
| Composition | Geotextile + 3D geonet + geotextile | Geotextile + sodium bentonite + geotextile |
| Permeability | High (drains water) | Ultra-low (watertight) |
| Self-sealing against perforations | — | Yes (bentonite expansion) |
| Typical application | Walls, basements, green roofs, foundations | Landfills, lagoons, 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 matrix → recommended product
| If your case is… | Recommended product |
|---|---|
| Drainage behind a retaining wall or basement wall | → Drainage geocomposite |
| Horizontal drainage under foundation slab with high subsoil moisture | → Drainage geocomposite |
| Residential green roof with irrigation and rain requiring drainage | → Drainage geocomposite |
| Sanitary landfill with perimeter system drainage | → Drainage geocomposite |
| Foundation on soil with high subsoil moisture | → Drainage geocomposite |
| Sanitary landfill base with ISO 14001 environmental audit | → GCL |
| Oxidation pond or water treatment plant | → GCL |
| Leachate cell in mining or chemical containment | → GCL |
| Agricultural reservoir or artificial lake with watertightness criteria | → GCL |
| Industrial reservoir on uneven terrain with curves and slopes | → GCL |
Before purchasing, define two pieces of information: whether water needs to pass (drain) or stop (be watertight), and whether the project has an environmental audit. The rule of thumb: drainage behind a wall or under a slab → drainage geocomposite; waterproofing of landfill bases, lagoons, or reservoirs → GCL. Combining functions is possible: in some landfills, GCL is used as a primary barrier with a drainage geocomposite on top to evacuate leachates. 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, lagoons, reservoirs, and hydraulic works with environmental criteria, the only correct option is GCL or HDPE geomembrane. Conversely: applying GCL where drainage is needed leads to accumulated hydrostatic pressure that damages structures and saturates the soil.
Not sure which geocomposite you need?
If you are combining drainage works with auditable hydraulic works, or have a project that requires both functions in different areas, ask the virtual assistant with the details of the work, applicable environmental criteria, and terrain characteristics. You will receive an instant technical recommendation.
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Frequently asked questions
Can I combine drainage geocomposite and GCL in the same project?
Yes. In sanitary landfills and lagoons, GCL is used as a primary waterproofing barrier with drainage geocomposite on top to control the evacuation of leachate or percolated water. Each material fulfills its function: GCL seals, drainage evacuates. The engineering design of the project 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. Its self-sealing capacity is maintained as long as water is available for hydration, and the confinement geotextiles prevent granule migration.
Does drainage geocomposite completely replace drainage gravel?
In most applications, yes, with significant savings in excavation volume, weight on structures, and transportation costs. For massive drainage works (large landfills with extreme loads), it is still combined with gravel or perforated pipe in the complete system, depending on the engineering design.