What kind of material is “geotextile“, what are its performance indicators, and what is its function? Let’s find out together!
Let’s dive right in now, and you can click on the question that interest you,
1 What is geotextile fabric?
Geotextile is permeable material geotextile made of polymer fibers through hot pressing and needling, gluing, and weaving, also known as geotextiles, including several types such as woven geotextile and non-woven geotextile.
2 Type of geotextile fabric
Geotextiles are mainly divided into two types: woven and non-woven.
Woven geotextiles include weaving method: plain weave method, circular weave method
Weaving method: plain weave method, twill weave method
Knitting method: warp knitting method, sewing knitting method.
Non-woven geotextiles include mechanical reinforcement method: needle punching method, hydroentanglement method
Chemical adhesion method: spray glue method, impregnation method
Hot bonding method: hot rolling method, hot air method.
Geotextiles can be used alone in engineering applications, and can also be used in combination with other geosynthetic materials such as geogrids, geomembranes and geonets.
3 The performance characteristics of geotextile
Woven geotextiles appeared in the 1960s and are characterized by high strength, high cost, poor back filtration and drainage functions, and limitations in engineering applications.
Non-woven geotextiles started in the late 1960s. Although China’s nonwoven fabric industry started late, it is developing rapidly. High-performance raw materials give the product high strength and durability, and advanced production technology gives the product good functions, which makes its application scope expand continuously.
With the promotion of needle punching nonwoven and spun bond nonwoven technology, the application area of nonwoven geotextiles is more extensive than that of woven geotextiles and has been developed rapidly.
4 The main material geotextile
At present, the raw materials of geotextiles are mainly synthetic fibres. The choice of various synthetic fibers needs to be combined with the actual engineering situation, taking into account both the requirements of the field used for its physical and chemical properties and the cost of the product, of which the most common applications are polyester and polypropylene fibers, followed by polyamide fibers and polyvinyl acetyl fibres. Polyester fibres have good physical and mechanical properties, excellent toughness and creep characteristics, high melting point, high-temperature resistance, aging resistance, mature production processes and a high market share. The disadvantages are poor hydrophobicity, easy to accumulate condensation when used for insulation materials, poor performance at low temperatures, ease to glass, reduced strength, poor resistance to acids and alkalis. Polypropylene fiber is good elasticity, instant elastic recovery than polyester fiber; acid and alkali resistance, abrasion resistance, mold resistance, excellent low-temperature resistance; has good hydrophobicity and core absorption performance, can make the moisture along with the fiber axial transfer to the outer surface; small density, only 66% of the polyester fiber, by repeated drafting can get a tight structure, superior performance of fine denier fibers, and then with the reinforcement process can make its strength more superior. The disadvantage is that it is not resistant to high temperatures, with a softening point of 130 to 160 °C. It has poor light resistance and is easy to age and decompose in sunlight, but it can be made UV resistant by adding UV absorbers and other additives.
In addition to the above-mentioned fibres, the raw materials of non-woven geotextiles can also be made from jute fibres, polyethylene fibres, polylactic acid (PLA) fibres and so on. Natural fibres and special fibres have gradually entered the various applications of geotextiles, such as natural fibres (jute, coconut shell fibres, bamboo pulp fibres, etc.) are used in road foundations, drainage, shore protection, soil erosion control and other fields.
5 The main functions of geotextiles
Geotextiles have a variety of uses, their main functions include filtration, drainage, isolation, reinforcement, protection and impermeability.
As geotextiles have good water permeability and air permeability, placing them in the soil structure allows the liquid inside the soil to pass through and be discharged, and at the same time plays the role of soil retention, effectively preventing the loss of upstream soil particles, fine sand and small stones, preventing the destruction of the soil and keeping the safety and stability of the project.
2) Drainage role
Geotextile is good water-conducting material, the material itself as a drainage channel can bring together the water inside the soil structure in the geotextile, along with the material slowly discharging the soil.
The isolation role refers to the geotextile can isolate two materials with different properties, to avoid mixing with each other and losing the integrity of various materials and structural integrity. Such as laying in ordinary railway ballast and roadbed between the geotextile can effectively isolate the gravel ballast and soil roadbed.
4) Reinforcing effect
Geotextile is placed inside the soil as reinforcing material, or geotextile is combined with soil to form a composite body. Compared with unreinforced soil, the strength and deformation properties of reinforced composite soil are significantly improved.
5) Anti-seepage effect
The composite of geotextile and geomembrane etc. has a low water (gas) permeability, which can stop the flow and diffusion of liquid or gas and play the role of impermeability or inclusion.
6) Protective effect
Soil loss caused by rainfall impact and surface water runoff can be reduced by setting geotextile protection measures.
If geotextiles are laminated with geonets and laid on the surface of exposed soil on slopes, erosion by precipitation and surface runoff can be effectively avoided or mitigated.
Sediment fences made of geotextiles can filter out suspended soil particles in turbid runoff, etc.
6 Main applications of geotextiles
1) Impermeable Engineering
In the fields of landfills, pollutant storage ponds, sewage treatment plants, environmental protection and water structure impermeability, geotextiles and geomembranes can achieve their impermeability function after compounding.
2) Sliding layer for high-speed rail ballastless track
In order to block the influence of the expansion and contraction deformation of the bridge due to temperature changes on the longitudinal track structure, to reduce the interaction between the track system and the bridge and to ensure the stability and smoothness of the track structure, China’s passenger rail lines have made a special arrangement for the “two cloths and one membrane” sliding layer, which is an important part of the CRTS II ballastless track system on the bridge. Two cloths and a membrane” sliding layer, i.e. 2 layers of geotextile with 1 layer of geomembrane (400 g cloth + 1.0 HDPE membrane + 200 g cloth) in between, and the geotextile of the isolation layer of the CRTS III ballastless track have strict requirements.
3) Fly ash, tailings ponds, mines, and other dumps
In order to reduce the stability of fly ash, tailing storage, mines, and other dumps and reduce the impact on the surrounding environment, geotextiles are used for reinforcement, isolation, and impermeability.
4) Ecological bag slope protection project
The ecological bag is made of polypropylene as the raw material of high strength, plane stable needle punching non-woven geotextile fabric processed into a bag. Ecological bags have strong corrosion resistance, UV resistance, non-degradation, can resist the erosion of insect pests, and anti-aging, acid and alkali salt erosion and microbial decomposition. Its water permeable and impermeable function can prevent the loss of filler (soil and nutrient material mixture) inside the bag, but also to achieve the normal exchange of water in the soil, the water required for plant growth can be effectively maintained and timely replenishment, plants can grow freely through the bag, the root system into the engineering foundation soil, the formation of the bag and the soil slope again between the solid role, is the highway and railway slope greening protection, barren mountain It is one of the important construction methods in the road and railway slope protection, barren mountain, mine restoration, riverbank slope protection, and inland river regulation.
Leave A Comment