Geotextiles and geogrids find applications in a variety of civil construction activities. In a variety of cases, these materials eliminate the need for the traditional aggregate construction materials and provide various economic and environmental benefits.
Geotextiles and geogrids are especially important for difficult regions (construction-wise) that are characterized by lands mostly covered by soil, lands that have soft subgrades or the ones that have sloping grounds. Such regions pose difficulties for various activities such as stabilization, reinforcement, draining, and isolation of grounds during construction. Geotextiles and geogrids provide stability and the desired aesthetics to such lands and make them fit for any construction activity and also help in extending their performance life.
Geotextiles and Geogrids help in saving millions of dollars every year by reducing the cost of repairing and reconstruction activities and enhancing the performance and tensile strength of many important civil engineering projects such as roadways, railways, etc.
These substances are easy for installation as well as very easy to work with. So, there are many application areas where the demand of these substances is huge and also essential in many ways.
Geotextiles are basically of three types – Woven, non woven and high strength woven. Geotextiles are indeed textiles in the generic sense, but are made from synthetic fibers such as polypropylene, polyethylene, polyester and polyamide rather than from natural fibers such as cotton, wool or silk. Thus, geotextiles do not degrade biologically, as other textiles made from natural fibers do.
These synthetic fibers are transformed into a permeable, flexible fabric by weaving them using standard weaving machinery or are matted together in a nonwoven, random manner. Some of these fabrics are also knit.
Geotextiles have at least 80 definite application areas; however, these fabrics almost always perform at least one of the following five discrete functions:
- Drainage: Geotextiles provide ways to gather the surplus water or rainwater in the soil, which is not functionally required by the structure, and discharge it.
- Filtration: Once drainage water is collected from a region, a proper interface between the drain and the surrounding soils is essential. A proper filtration is provided by geotextiles.
- Separation: geotextiles prevent the mixing between different layers of soils that may have different particle sizes or properties.
- Reinforcement: the high tensile strengths and high soil-fabric friction factor of geotextiles allow their use in reinforcing earth structures.
- Protection: erosion of lands due to many reasons such as water currents, wave actions, and repeated drawdown make lands weaker. So, the use of mattress structures or rock beaching is very essential in erodible lands. Beneath the mattress structures and rock beaching, a layer of geotextiles is generally provided to add extra strength.
Geogrids are a distinct category of geosynthetics that are especially designed for the reinforcement of a land. These products feature arrays of large apertures that are uniformly distributed throughout the structure. The apertures refer to the openings between the transverse and longitudinal elements of the structure and are functionally very essential to geogrids’ design. These apertures allow soil particles on either sides of the structure to come in direct contact with each other, thus improving the interaction between the geogrid and the surrounding soils.
Geogrids are broadly divided into two types:
- Multifilament, high tenacity polyester yarns, woven in a stable network and coated with PVC material.
- Grids of extruded polypropylene, made by combining two and three biaxially oriented layers of highly tensile polypropylene material.
Geogrids perform functions such as:
- Stabilization: when the base material of a land is compressed over geogrids, the base material is sealed, locking the aggregate structure together in a rigid way, thus allowing stabilization of soils.
- Confinement and base reinforcement: geogrids keep the fill material undisturbed at its original position and allows for interlocking of the base.
- Stress transfer: geogrids distribute the loads applied upon them over a larger area and tghus reduce the vertical pressure on the underlying structures.
Use of Geotextiles and Geogrids in civil construction projects provides numerous benefits by improving sub grade performance of the land. These substances are found to improve subsurface filtration and drainage, maintain structural base, reinforce the soils, aid in controlling soil erosion and sedimentation, stabilize railways and roadways and enhance various containment projects.