The Functions and Applications of Geotextile and Geomembrane

Geotextile and geomembrane are two essential geosynthetic materials widely used in hydraulic engineering, transportation infrastructure, environmental protection, mining, and municipal projects.

Although they are often mentioned together, their functions are different — and in many cases, they are used as a composite system to achieve optimal waterproofing and soil stabilization performance.

What Is Geotextile and What Is Its Function?

Definition

Geotextile is a permeable geosynthetic material made from synthetic fibers such as polyester (PET) or polypropylene (PP). It is manufactured by needle-punching or weaving processes.

Finished products are typically supplied in rolls:

• Width: 4–6 meters

• Length: 50–100 meters

Geotextiles are classified into:

• Woven geotextile

• Nonwoven geotextile (short fiber or filament)

Main Functions of Geotextile

Geotextiles provide:

✔ Filtration
✔ Drainage
✔ Separation
✔ Reinforcement
✔ Protection
✔ Soil stabilization

Because geotextiles are permeable, they allow water to pass while preventing soil particle migration.

Typical Applications of Geotextile

1. Hydraulic engineering

• Riverbank and slope protection

• Seawall reinforcement

• Canal lining support

• Dam filtration layers

2. Transportation infrastructure

• Road and railway subgrade separation

• Airport runway stabilization

• Retaining wall reinforcement

• Drainage layers

3. Environmental engineering

• Landfill separation layers

• Ash pond containment

• Tailings dam stabilization

What Is Geomembrane and What Is Its Function?

Definition

Geomembrane is an impermeable polymer liner used for containment and waterproofing. It is primarily made from:

• HDPE (High-Density Polyethylene)

• LDPE (Low-Density Polyethylene)

• EVA

HDPE geomembrane is the most widely used type.

It is manufactured using polyethylene resin blended with:

• Carbon black (UV protection)

• Antioxidants

• Anti-aging agents

• UV stabilizers

Core Function of Geomembrane

The primary mechanism of geomembrane is:

To block seepage channels using the impermeability of plastic film, while relying on high tensile strength and elongation to withstand hydraulic pressure and ground deformation.

In simple terms:

✔ Prevent water leakage
✔ Stop contaminant migration
✔ Provide waterproof and moisture barrier

Its impermeability performance depends mainly on the quality of the polymer film.

Key Performance Characteristics

1. High tensile strength

2. Excellent elongation capacity

3. Strong chemical resistance (acid, alkali, salt, oil)

4. Wide temperature resistance (approx. -70°C to 110°C)

5. Excellent UV and aging resistance

6. High flexibility and adaptability to uneven settlement

Main Applications of Geomembrane

Environmental Protection

• Landfills

• Wastewater treatment plants

• Solid waste containment

Water Conservancy

• Reservoirs

• Dams

• Canal lining

• Artificial lakes

• Water storage ponds

Mining

• Heap leach pads

• Tailings ponds

• Sedimentation ponds

Aquaculture

• Fish ponds

• Shrimp farms

• Aquaculture lining systems

Petrochemical Industry

• Oil tank secondary containment

• Chemical storage ponds

Municipal Engineering

• Subway waterproofing

• Underground structures

• Green roof systems

What Is Composite Geomembrane (Geotextile + Geomembrane)?

Composite geomembrane is formed by bonding geotextile to one or both sides of a geomembrane sheet.

Common types include:

• One geotextile + one membrane (1G1M)

• Two geotextiles + one membrane (2G1M)

• Multiple-layer composite systems

Why Combine Geotextile and Geomembrane?

The geotextile layer:

• Increases tensile strength

• Improves puncture resistance

• Enhances friction coefficient

• Protects the membrane from mechanical damage

The rough surface of geotextile increases interface friction, improving system stability.

This composite structure provides:

✔ Waterproofing
✔ Drainage
✔ Reinforcement
✔ Soil protection

Composite Geomembrane Installation Method

Proper installation is critical for long service life.

Step 1: Subgrade Preparation

• Level the base with fine sand or clay

• Remove sharp stones

Step 2: Liner Placement

• Do not overstretch the geomembrane

• Allow slight slack to accommodate settlement

• Anchor both ends into trench with wave-shaped allowance

Step 3: Protective Layer

• Cover with 10 cm fine sand or clay

• Add 20–30 cm stone or concrete blocks as protective layer

Avoid dropping stones directly onto the membrane.

Step 4: Edge Anchoring

• Use expansion bolts and steel strips

• Seal joints with asphalt coating to prevent leakage

Advantages Compared with Traditional Waterproofing

Compared with masonry or concrete lining systems, geotextile and geomembrane systems offer:

• Lower investment cost

• Faster installation

• Shorter construction period

• Better anti-seepage performance

• Higher channel efficiency

• Longer service life when protected from sunlight

Conclusion

Geotextile and geomembrane serve different but complementary functions:

• Geotextile → filtration, drainage, reinforcement

• Geomembrane → impermeable barrier

When combined as composite geomembrane, they provide a highly efficient and durable solution for hydraulic, environmental, mining, and infrastructure projects.

Modern geosynthetic systems have become an essential part of global infrastructure development due to their reliability, cost efficiency, and long-term engineering performance.