Functions

Geotextiles are specially fabricated to be used in geotechnical, geoenvironmental, hydraulic and transportation engineering applications. It is convenient to identify the primary function of a geosynthetic as being one of: separation, filtration, drainage, reinforcement, erosion control and asphalt absorption. In many cases the geosynthetic may serve dual functions.

Separation

Separation

Geotextiles maintain the integrity of civil engineering structures by keeping critical construction materials separated.

Placing a geotextile between two different materials indefinitely maintains the separation between those materials. The polypropylene composition of the geotextiles resists chemical and biological degradation lasting indefinitely in buried applications. Materials adjacent to the geotextile form a frictional bond and these materials are stabilized and maintain their designed position and layer thicknesses in roads.

Filtration

Filtration

As a filter, geotextiles allow water through systems wilthout damaging erosion.

Geotextiles may provide a filter, retaining larger particles while letting very small particles pass through. In the necessarily static application, this filtration allows the media adjacent to the geotextile to form a filter within its own particle structure, to keep finer particles from reaching the geotextile. Nonwovens are typically more efficient filters with finer pore openings. Openings in wovens can vary from random openings between yarns to calculated, very regular opening specifically designed for targeted filtration applications.

Drainage

Drainage

Fluids may drain in the plane of a geotextile.

Geotextiles most often facilitate drainage by performing as a filter while allowing fluids to pass through. Most often, a free-draining media is placed adjacent to the geotextile and the geotextile performs the functions of separation, filtration and drainage. Nonwoven geotextiles can also allow drainage of fluids within the plane of the geotextile—lateral drainage.

Reinforcement

Reinforcement

The strength of geotextiles can reinforce structures.

Geotextiles provide varying degrees of reinforcement in civil engineering applications. Local reinforcement helps maintain the separation of particles trying to push through the fabric. Areal reinforcement can add membrane-like support to a layered system to resist deformation due to loading. Planar reinforcement is employed to strengthen structures through direct support. Strong geotextiles may also be effectively sewn to fabricate reinforced structures.

Protection

Protection

The bulk and strength of nonwoven geotextiles can protect systems.

Nonwoven geotextile can be manufactured at significant thickness to be used as a protective cushion to prevent damage to adjacent layers such as membrane systems in landfills, ponds, etc.. The strong fibrous structure will resist puncture from sharp objects.

Asphalt Absorption/Barrier

Asphalt Absorption/Barrier

Asphalt saturated nonwoven geotextile layers enhance pavement performance.

Nonwoven geotextiles can absorb hot, liquefied asphalt cement or asphalt emulsions to become a uniformly saturated moisture barrier. The fibrous structure holds the saturant in place while maintaining sufficient strength to resist construction damage.