Lining sanitary landfill bases according to environmental standard ISO 14001, oxidation ponds and reservoirs with contractual auditing, where conventional HDPE geomembranes require neat welding and meter-by-meter pressure testing, demands a self-sealing sodium bentonite clay barrier geocomposite with self-protection capability. This clay barrier geocomposite (GCL) —also called geosynthetic clay liner, bentonite geomattress or bentonite GCL— is manufactured by MOLTEXO with a sodium bentonite core between two layers of needle-punched geotextile, in rolls 5.8 m wide and 40 m long, designed for landfills, mining, chemical containment, and hydraulic works with environmental criteria.
Key benefits
- Ultra-low permeability due to bentonite hydration: when moistened, sodium bentonite expands 10-15 times its dry volume, creating a monolithic layer with permeability lower than compacted site clay, a critical condition for landfills and leach pads with environmental auditing.
- Self-sealing capacity against perforations: if the barrier suffers a small perforation, the adjacent bentonite expands with the incoming water and automatically seals the breach, a differential advantage over HDPE geomembranes that require manual repair of each damage.
- Adaptation to ground irregularities: the flexible material adapts to curves, slopes, and irregular shapes without the need for cutting and welding, a differential condition compared to rigid geomembranes that require a flat prepared ground and complex welding for every change in geometry.
- Mechanical reinforcement with double geotextile: the upper and lower layers of needle-punched geotextile provide tensile and shear strength, protect the bentonite against perforation by stones, and ensure that the material withstands the thrust of the upper backfill for decades.
- Compatible with environmental criteria: sodium bentonite is a natural mineral without synthetic chemical compounds, an appropriate condition for projects with environmental auditing that require materials with low impact.
Typical applications and uses
- Lining of bases in sanitary landfills and backfill cells compliant with ISO 14001 or equivalent.
- Oxidation ponds, wastewater treatment plants, and industrial reservoirs requiring watertightness.
- Leach pads in mining and containment of chemical solutions in industrial projects.
- Artificial lakes, agricultural reservoirs, and landscaping works with water bodies requiring waterproofing.
Quality and durability
An economical GCL fails in two areas: the bentonite is calcium-based or of low mineral quality (resulting in significantly less expansion than quality sodium bentonite and much higher permeability than declared), and the confining geotextiles are sparse (leading to granule migration and areas lacking bentonite). MOLTEXO works with controlled-origin sodium bentonite and calibrated-weight geotextiles, which distinguishes an auditable environmental GCL from a generic geomattress that does not meet declared permeability.
How does the GCL clay barrier waterproofing actually work?
By expansion of sodium bentonite when hydrated. The core of bentonite granules is encapsulated between two geotextile layers. When water contacts the material, the bentonite absorbs water and swells 10 to 15 times its dry volume, becoming a cohesive layer with extraordinarily low permeability (10⁻¹¹ m/s, more impermeable than compacted clay on site). This monolithic layer blocks water passage very efficiently, with no need for welding or joints like those required by conventional HDPE geomembranes.
What's the function of the outer geotextile layers?
Three indispensable complementary functions. Bentonite confinement: the upper and lower layers keep the granules in place before and after hydration, preventing water from washing the expanded clay away. Mechanical reinforcement: they add tensile and shear strength that pure bentonite does not have, a condition for resisting fill thrust on site. Puncture protection: they act as a buffer layer against fill stones and impacts during installation. The bond between the two geotextile layers via needle-punching ensures structural cohesion of the composite for decades.
What does the GCL's self-sealing or 'self-healing' capacity mean?
If the barrier suffers a small puncture (accidental impact during installation, plant root, fill perforation), the sodium bentonite next to the damage hydrates with the incoming water, expands up to 10-15 times its dry volume and fills the gap automatically. This condition differentiates GCL from HDPE geomembrane: a puncture in HDPE produces a continuous leak until manual repair; a small puncture in GCL self-seals within minutes once moistened. For larger punctures (tens of centimeters) self-sealing is not enough and patch repair is required; self-sealing works well on point punctures up to a few centimeters.
Can it be installed permanently exposed to Caribbean sun?
No. The GCL is designed to operate confined under a layer of fill (soil, sand, gravel) or protective cover. Cover after installation: typical operating rule is 14-30 days. Prolonged direct exposure produces two problems: UV degradation of the geotextiles confining the bentonite, and cyclic hydration from rain and subsequent drying that gradually reduces the effective expansion capacity of the clay. Cover also provides the weight needed for the bentonite to expand against a restraint and form the monolithic impermeable layer that delivers functional sealing.
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| Material and construction | |
|---|---|
| Composition | Woven geotextile + bentonite + PE film |
| Mass per unit area | ≥4000 g/m² (0.82 lb/ft²) |
| Dimensions and format | |
| Roll width | 5.8 m (19 ft) |
| Roll length | 40 m (131 ft) |
| Coverage area per roll | 232 m² (2497 ft²) |
| Estimated minimum roll weight | 928 kg (2046 lb) |
| Length and width tolerance | -1% |
| Strength and performance | |
| Tensile strength | ≥700 N/100mm (40 lb/in) |
| Elongation under maximum load | ≥10% |
| Peel resistance (PE and nonwoven) | ≥30 N/100mm (1.71 lb/in) |
| Peel resistance (woven and nonwoven) | ≥40 N/100mm (2.28 lb/in) |
| Hydrostatic resistance | 0.6 MPa, 1h, no leakage (87 psi, 1h, no leakage) |
| Hydraulics and filtration | |
| Permeability coefficient | ≤5.0 × 10⁻¹² m/s (1.64 × 10⁻¹¹ ft/s) |
| Fluid loss by filtration | ≤18 mL (0.61 fl oz) |
| Durability and protection | |
| Durability | ≥20 mL/2g |
| Physicochemical properties | |
| Methylene blue absorption capacity | ≥30 g/100g |
| Swell index | ≥24 mL/2g |
| Presentation and packaging | |
| Presentation | Roll 5.8 m (19 ft) wide × 40 m (131 ft) long |
Normas ASTM| Roll: Width | 53.0 cm (20.87 in) |
|---|---|
| Roll: Height | 53.0 cm (20.87 in) |
| Roll: Depth | 580.0 cm (228.35 in) |
| Roll: Weight | 928.0 kg |
Official MOLTEXO warranty
What's covered
Confirmado el defecto: sustitución o devolución del valor pagado.
What's not covered
Payment & Security
