Geosynthetics
This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites.
These products have a wide range of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture.
These synthetic fibers are made into flexible, porous fabrics by standard weaving machinery or are matted together in a random non woven manner.
There are at least 100 specific application areas for geotextiles that have been developed; however, the fabric always performs at least one of four discrete functions: separation, reinforcement, filtration, and/or drainage.
Rather than being a woven, nonwoven or knitted textile fabric, geogrids are polymers formed into a very open, gridlike configuration, i.e., they have large apertures between individual ribs in the transverse and longitudinal directions.
Geogrids are (a) either stretched in one, two or three directions for improved physical properties, (b) made on weaving or knitting machinery by standard textile manufacturing methods, or (c) by laser or ultrasonically bonding rods or straps together.
Their growth in the United States and Germany was stimulated by governmental regulations originally enacted in the early 1980s for the lining of solid-waste landfills.
Geofoam is a polymeric product created by processing polystyrene into a foam consisting of many closed cells filled with air and/or gases.
The resulting product is generally in the form of large, but extremely light, blocks which are stacked side-by-side and in layers providing lightweight fill in numerous applications.
The cellular confinement reduces the lateral movement of soil particles, thereby maintaining compaction and forms a stiffened mattress that distributes loads over a wider area.
Traditionally used in slope protection and earth retention applications, geocells made from advanced polymers are being increasingly adopted for long-term road and rail load support.
Geodrains are prefabricated product consisting of one or more polymeric core elements transporting fluid (perforated mini-pipes, geonets, cuspated sheets) and one or more geosynthetics separating the flow region from the surrounding environment.
For example, a geotextile placed on soft soil will usually be designed on the basis of its reinforcement capability, but separation and filtration might certainly be secondary and tertiary considerations.
Also involved is the application of basal reinforcement over soft soils and over deep foundations for embankments and heavy surface loadings.
Stiff polymer geogrids, with very open apertures, in addition to three-dimensional geocells made from various polymers are also increasingly specified in unpaved and paved roadways, load platforms and railway ballast, where the improved loadbearing characteristics significantly reduce the requirements for high quality, imported aggregate fills, thus reducing the carbon footprint of the construction.
Filtration is the equilibrium soil-to-geotextile interaction that allows for adequate liquid flow without soil loss, across the plane of the geotextile over a service lifetime compatible with the application under consideration.
Drainage is the equilibrium soil-to-geosynthetic system that allows for adequate liquid flow without soil loss, within the plane of the geosynthetic over a service lifetime compatible with the application under consideration.
Drainage applications for these different geosynthetics are retaining walls, sport fields, dams, canals, reservoirs, and capillary breaks.
Containment involves geomembranes, geosynthetic clay liners, or some geocomposites which function as liquid or gas barriers.
