Increase in the world population and increasing needs of the people, quality and fast life expectations and huge infrastructure investments in the fields of construction and transport increased the importance of geotextiles.
Geotextile, which is derived from the words of geo – which means earth or soil – and textile, is one of the oldest formats of the textile structures. In the Ancient Egypt, knitted surfaces, nonwovens such as geotextiles used in order to support the edges of buildings and rivers and warp knitting fabrics are used for similar purposes in today’s world.
In recent times, nonwovens and warp knitting structures are used for geotextile applications increasingly more commonly. Geotextiles have a constantly growing place in the field of civil engineering, in particular.
Geotextiles which are manufactured out of synthetic fibres instead of natural fibres such as cotton, wool etc. are used in civil engineering to support the vertical and upright edges of the soil, construct solid floors for temporary and permanent roads and highways and furnish ground waterways. In this way, the soil filters itself; the waterways are not filled up with soil; erosion behind the rocks and stones is prevented in the river side and coast.
Membranes used within the soil or in contact with the soil are named “geosynthetics” in civil engineering. This term covers geotextiles, plastic grills and impermeable membranes. It is accepted that the most important one is the geotextiles among geosynthetics. Geotextiles can be in the form of continuous or incontinuous fibres or in the form of knitted, woven and nonwoven fabrics. Geotextiles have an endless area of application ranging from division, filtration, drainage, reinforcement, erosion control and prevention. According to the purpose of use, the most important performance characteristics of geotextiles vary, which include pulling, tearing, perforation, air and water permeability, heat insulation, pore size, thickness and grammage.
Geotextiles Resistant to Mechanic Stress
The most important requirement of the geotextiles is to ensure continuous functionality and this feature can be ensured with different textile structures. Geotextiles need to meet numerous demands. Among these needs, resistance to mechanic stress and resistance at cross direction come to the fore.
In general, nonwoven, woven fabrics manufactured out of synthetic fibres and composites are used as separator layer. Selection of the correct textile product relies on the grain size of the main material and the expected load during construction.
Filtration is the most important application: the most important factor is the water pressure in the damaged walls, dams or artificial barriers. As a filter, geotextile keeps the soil components or other particles and allows the passage of others with the water. The aim of low pressure should be maintained in the water drainage while the mechanic stress between the soil retention and hydraulic filter efficiency should be distinguished. Thus, the thickness of the geotextile plays a key role and is effective in the mechanic and hydraulic performance of the filter in the long run.
Geotextile for a Strong Drainage
Expectations from geotextiles for drainage are almost the same as what is expected from filtration materials. Drainage systems can be individual components or elements constituting a system. In the drainage layer, no pressure decrease is tolerated and what is kept should be removed. Drainage systems manufactured out of geotextiles can replace classical concrete and plastic tube structures.
Protection and strengthening in order to avoid of mechanic damage to the materials such as sealing strips or coating materials that are mostly used in the interior parts are significant functions of geotextiles.
Nonwovens or composites can be used as protective layers. For the protection function, drift stroke and impact resistance are of paramount importance in addition to the thickness levels of the layer and geotextile surface. Protective geotextiles are used in the tunnel and land sealants with the aim of protecting the low-permeable materials. Reinforced geotextiles placed between or beneath the soil layers improve the mechanic properties of the soil layer. Nonwovens or geotextiles in the form of geo-grill can be used for supporting the dams established on the unstable lands. Reinforcement provides cost advantage as complex construction measures are avoided.
Anti-Erosion Geotextiles
Protective and reinforcement geotextiles can also be used for controlling erosion. Geotextiles which provide erosion control ensure that the nature has the necessary time for strengthening of the plant and tree roots by strengthening the soil structure.
Geo-grills are becoming more and more popular. They are used for reinforcement and the area of usage includes separation, filtration for removal of snow flakes, fluid absorption, erosion control, mechanic protection and ground stabilization in road-bridge construction. Depending on the last area of usage, geo-grills can be manufactured at varying openness sizes to distribute the static and dynamic loads in a balanced manner.
Although there are not official data concerning the production of geotextiles in Turkey, it is estimated that 4.5 million square meters of nonwoven geotextile and 600 thousand square meters of woven geotextiles have been manufactured. Our country imported geotextiles for the first time during the highway constructions of 1980s as well as the construction works of Atatürk Dam in 1983.
Increase in the world population and increasing needs of the people and quality and fast life expectations necessitate immense infrastructure investments in the fields of construction and transport. In the field of construction, huge dams are built while immense highways, railways and airports are constructed in the field of transport. These structures constitute a great potential for geotextiles.
