Geosynthetic Material
The geosynthetic material is a permeable fabric that improves the strength and stability of soil. It is used for many civil engineering structures like separation, filtration, isolation, reinforcement and protection.
Woven, nonwoven and knitted geotextiles are mainly used for separation in paved road construction, encapsulation of swelling soils and waste containment. Some special geosynthetic materials and geocomposites are also used.
Filtration
A geotextile is a fabric that is placed between different layers of soil or rock. They are designed to prevent soil erosion, filter water, and separate various layers of ground. They can also enhance soil stability. They are often made from synthetic fibers, but they can be combined with natural fibres to form geocomposites. These geosynthetic materials can also have additional functions, including drainage and reinforcement.
Filtering geotextiles are usually made from synthetic materials such as polypropylene (fPP). They are generally woven or mat-like and have good permeability to liquids and gases. This makes them useful in a variety of applications, including landfill liners, asphalt pavement overlays, and encapsulation of swelling soils.
Soil erosion is a common problem that can cause tremendous damage to roads, railways, buildings, and other infrastructure. The erosion process can be sped up by many factors, including weather and human activity. In order to control erosion, geosynthetics can be used for slope protection, river bank stabilization, and land development.
Composite geosynthetics can be formed from different types of geotextiles, geomembranes, and geogrids. These materials can have a wide range of functions and are used in construction projects such as embankment support, dams, road construction, and railway construction. They are also used in waste containment, landfills, and environmental protection. Geosynthetics can be manufactured in a controlled factory environment, which allows for greater quality control than is possible with outdoor soil and rock construction. They are also subject to published standards and design methods from organizations such as ISO, ASTM, and GSI. Approximately twenty universities teach stand-alone courses on geosynthetics and almost all include the topic in geotechnical, geoenvironmental, and hydraulic engineering courses.
Isolation
The other major group of geosynthetic materials is the non-woven geotextiles. These are textiles that use synthetic fibers rather than natural ones and hence are less susceptible to bio-degradation. They are manufactured either by standard weaving machinery or matted together in a random non-woven fashion. These fabrics have excellent filtering, isolation, reinforcement and protection capabilities.
The third large group of geosynthetics is the geomembranes. These are relatively thin, impervious sheets of polymeric material that are primarily used as linings or covers for liquids or solids storage facilities such as landfills and surface impoundments. They also play a role in anti-seepage and drainage.
Lastly, there are the field-coated geotextiles, which are field applied to soil to impede flow of fluids or gases. These are commonly used for erosion control, asphalt pavement overlays, encapsulation of swelling soils and waste containment.
Another specialized category of geosynthetics is the active geosynthetics. These are products that initiate electrokinetic phenomena in the Geosynthetic material geotextile surrounding soil, such as electro-osmosis and electrophoresis (see below). The properties of these materials are based on a number of factors, including the time and temperature at which they are tested. Hence, they are not readily transferable from one lab to the other and they require a high level of technical expertise to design with them.
Reinforcement
Geosynthetic clay liners are rolls of factory-fabricated thin layers of bentonite clay sandwiched between geotextiles or bonded to a geomembrane. They are commonly used as composite components beneath a geomembrane in geoenvironmental, containment and transportation applications.
Clogging is an ongoing challenge for geotextiles, geonets, geogrids and geocomposites that are exposed in unfriendly environments. Loess soils, fine cohesionless silts and microorganism laden liquids can clog these polymeric materials, necessitating detailed design evaluations.
Geotextiles can be used to prevent soil particles from migrating into drainage aggregate or pipes and are often used underneath rip rap in coastal and river bank protection systems. They can also be incorporated into track transitions to provide a layer of separation and reinforcement between the granular ballast and the more compacted subgrade.
High-strength geotextile reinforcement can increase the strength and stability of soil by introducing shear resistance to the system. Geo Bag Sand Bag To be effective, the reinforcement must intersect the potential failure surface of the soil mass to generate strains that develop tensile strengths in the soil-reinforcement interface.
New multifunctional geosynthetic materials are emerging that can provide two or more conventional functions in one unit. Examples include geocomposite geotextiles, smart geosynthetics that can transmit critical management information and active geosynthetics that change their surroundings rather than simply reacting to it. These are enabling a broader range of applications for these versatile materials and creating significant changes in the construction industry.
Protection
As geosynthetics are polymeric, they don’t degrade under most conditions and can withstand a significant amount of stress. This means they can be used under a wide range of soil conditions and still perform at their best. This is a key feature, especially for projects with difficult to work with soils or unusual environmental conditions.
The polymeric nature of the material also helps with resistance to bioclogging, which can be a serious problem for some soils and situations. This is particularly important when working with loess soils, fine cohesionless silts or highly turbid liquids like farm runoff. Special attention is needed to design geotextiles, geonets, and geopipe for these types of challenging environments.
Another common use of geosynthetics is for erosion control. Erosion is a natural process that can cause significant damage to existing structures, landforms and buildings. Using a geotextile or geomat to slow the progress of erosion can be a cost-effective way to protect the environment and improve the stability of a site.
In addition to the conventional functions of a geotextile, new applications are being developed with multifunctional geosynthetic materials. These include composite geotextiles that combine two or more of the conventional functions, smart geosynthetics that provide critical management information and active geosynthetics that change their environment rather than simply acting in a passive role.
