Geosynthetic Material Geotextile – Types and Functions
Geosynthetic material geotextile perform a variety of functions that allow civil engineering projects to be constructed economically, environmentally and with greater resilience than is possible using conventional materials. This Tensar guide introduces you to the different types and functions of these revolutionary products.
Woven and nonwoven fabrics, geonets, geogrids, geosynthetic clay liners, geomembranes and geocomposites all belong to the broad category of geosynthetics. These products serve eight main functions:
Durability
While most geosynthetics play a passive role, the newer multifunctional geosynthetics are active materials that change their environment. These include composites that provide two or more conventional functions in one material, smart geosynthetics that can communicate critical management information and active geosynthetics which initiate electrokinetic processes.
Reinforcing geogrids and high strength geotextiles can provide an early increase in tensile resistance that helps prevent the over-stressing of foundation soils as construction progresses. They can also construct earth slopes with steeper angles than would be possible using natural or reinforced soil walls. A good example is the Tensar TriAx geogrids used to construct a railway embankment over soft foundations for the Gemas Mentakab project in Malaysia.
Drainage geosynthetics, usually a drainage geocomposite, pass water (and other fluids) through their structure to an open space or collector. They can dissipate pore water pressure beneath roadways, intercept groundwater in slopes and behind retaining walls, or provide edge drainage to road pavements.
Protection geotextiles, which are primarily nonwoven NW-NP materials (based on fiber length), act as a barrier to separate dissimilar materials such as between in situ soil and aggregate. They can be used in construction of roads and railways, in slope stabilization, mud control, and landfills. Protection geotextiles are less common than drainage or reinforcement geosynthetics. This is because most protection geotextiles are not needed for their conventional functions, such as filtration or drainage.
Drainage
While geotextiles can be designed to be barriers, many are also designed with drainage functions. Drainage geosynthetics, which are often called geotextile clogging inhibitors or preventers, allow water and other liquids (and gases) to pass through the fabric and into a collection system. Geosynthetic material geotextile This is an important function for roads, railways and other infrastructure where pore water pressure can lead to the softening of road base soils and the loss of structural strength of the road.
Another common function of geosynthetic materials is separation. This is achieved by placing a flexible geotextile between dissimilar materials to create a separating layer, allowing the integrity and functioning of both materials to remain intact or even improve. Examples include paving roads, railroad bases and the use of thick nonwoven geotextiles as cushioning under geomembranes.
In addition to drainage, some geosynthetics are designed with filtration and ponding control functions. These are most commonly in the form of geocomposites, which combine a drainage core with one or more layers of geotextile. The drainage core may consist of nubbed, dimpled or cuspated polymer sheets, biplanar or triplanar networks of stiff polymer fibers in various configurations, or perforated micropipes. In filtration applications, adequate fabric open area, high permeability and the ability to retain soil are important design criteria.
Stabilization
Increasing the bearing capacity and stiffness of soil by mechanical stabilisation is one of the most common applications for geosynthetic materials. Tensar’s range of products includes a wide variety of geotextile stabilisers, from filter to high-strength reinforcement. For example, geogrids can be placed below ballast layer to control lateral migration of aggregate and deterioration of the trackbed material, while geocomposites can replace sand filters in rail embankment construction. Visit this page to learn more about how Tensar products improve rail trackbeds.
Separation is the placement of a flexible geosynthetic material like a geotextile between dissimilar materials to ensure that their integrity and function remain intact or improved. Examples of this are the optimization of paved roads, unpaved roads and railroad bases. This also includes thick nonwoven geotextiles used for cushioning and protection of geomembranes.
Filtration is the equilibrium soil-to-geotextile interaction that allows for adequate liquid flow without excessive soil loss. This is a primary function of many geotextiles, particularly when combined with a drainage core in the form of a geocomposite. Some applications include highway underdrain systems, retaining wall drainage and landfill leachate collection systems. In addition, geosynthetic clay liners and some geocomposites function as liquid or gas barriers in tunnels, dams, canals, surface impoundments and floating covers.
Flexibility
The use of Geosynthetic materials for the construction of civil and transportation infrastructure projects provides a number of advantages. These include the ability to reduce maintenance costs, prevent structural damage, and provide a more sustainable solution. The material’s durability and flexibility are also a plus. These factors have contributed to their widespread acceptance by civil engineers and the construction industry worldwide. Geosynthetic materials primarily made from various polymers are used for the construction of roadways, embankments, and bridge approach slabs. In addition, they are often used in retaining walls and dams. This is because they are more durable than concrete or piled retaining walls and require less maintenance.
Geosynthetics are manmade products that can be planar or strips and come in a variety of shapes. Different types are designed to deliver varying functions, such as stabilisation, reinforcement, Geosynthetic clay liner separation, filtration, drainage and erosion control. Some are even able to perform a combination of these functions.
In some cases, Geosynthetics can be combined to create a single product that delivers multiple benefits, known as a geocomposite. Examples of this are a stabilisation and drainage geogrid or a separation and filtration geotextile. These are particularly useful in drainage and containment applications as well as road foundation situations where the migration of fine soil can be an issue. For an example of a successful application, see the Green Lane Rail case study on Tensar’s high-strength Basetex geotextile.
