Md. Imran Hossain
Link to EcoGeoX
Geo textiles is a branch of technical textiles. As we know the prefix of geo-textile, &#;geo&#; means &#;earth&#; and the &#;textile&#; means &#;fabric&#;. So, geo textiles can be defined as the permeable textile materials used with foundation, soil, rock, earth or any other civil engineering materials as an integral part of man-made projects, structures or systems. Geo-textiles are mainly made of polypropylene, polyester, polyamide etc. These are primarily used in civil engineering or construction such as tunnel construction, drainage, filtration, reinforcement, erosion control, landfilling, groundwater protection etc. It changes the characteristics of the soil and makes it suitable for the construction of buildings in ineffective places.
Geotextiles were originally used as an alternative to the filters used for granular soil. The most commonly used term for geotextiles is filter cloth. Originally in the s R.J. Barrett first used geotextiles behind precast concrete sea-beds, precast concrete erosion control, and geotextiles are primarily used under large rock fragments and other erosion control situations. R.J. completed this work using various styles of woven monofilament fabrics. He discussed the need for both sufficient fabric strength and proper stretch, as well as adequate permeability and soil retention, and recommended the use of geotextiles in filtration situations. Since the early s, non-woven geotextiles have been used in various fields of civil engineering for separation, filtration, protection and drainage.
Classification of Geo textiles Based on Manufacture Geotextile is a distinguishable synthetic material made of textile materials. They are mostly made from synthetic fibers such as polyester or polypropylene also made from some natural fibers. There are many types of geotextile:
1. Woven Geo-textile:
A woven fabric consists of two sets of orthogonally interlaced filaments or staple-fiber yarns. Woven geotextiles perform separation and reinforcement functions and increase the strength of the soil. As the strength of their warp yarns is much higher, so they have more tensile strength. As a result, it is able to take much more load than others. There are various types of woven geo-textiles like woven monofilament, woven multifilament, woven slit-film monofilament, slit-film multifilament and so on.
2. Non-woven Geo-textile:
Nonwoven fabrics are defined as a web or sheet of randomly or/and directionally oriented fibers/filaments, bonded either mechanically, chemically or by other using other methods like friction, and/or cohesion, and/or adhesion. Though the tensile strength of non-woven geo-textile materials is not very high, but their separation, drainage and filtration ability are better than other type of geo-textiles. Non-woven geo textiles are permeable geosynthetics, usually made by synthetic fibers such as polypropylene, polyethylene etc. Thermal and chemical bonding methods are also used to make non-woven geo-textiles. There are various types of non-woven geo textiles like continuous filament heat bonded, continuous filament needle punched, staple needle punched, resin bonded and so on. In the world of fabric production, the spun bonding method is very popular and is considered as the fastest production method for non-woven fabrics.
3. Knitted Geo-textile:
Knitted geo-textiles are produced by mostly using warp knitting technology, interlocking a series of loops of yarns or filaments to form a planar structure. The loops in the knitted structure are interlocked in many ways, similar to woven structure These type of textile materials have good flexibility property and are economically profitable. Although the use of knitted geotextiles is less, but the demand of knitted geotextiles for the function of &#;Drainage&#; and &#;Soil Erosion Control&#; is increasing day by day. Knitted geotextiles are made by using knitting technology, in few times weaving is also used to make these products.
4. Braided Geo-textiles:
Braiding is one kind of fabric production technology, generally used for producing narrow & rope-like materials by interlacing diagonally three or more strands of yarns or filaments. The braided structure geo-textiles can be categorized as biaxial and triaxial braids; both have two sets of braider strands, each strand aligned in the bias direction, but the latter also have an additional set of strands aligned parallel to the braid axis.
In addition to these type of geo-textiles, other geo-textiles products are- Geo-nets, Geo-grids, Geo-cells, Geo-membranes, Geo-composites etc. Each of these has its own characteristics and is used for special applications like civil & road or railway constructions.
Raw Materials for Geo-textiles
Different types of fibers from both natural as well as synthetic category can be used as geotextiles for various applications.
Natural Fibers: Natural fibers in the form of paper strips, wood pulps, jute nets or wool mulch are used to produce geotextiles. Usually, geotextiles have to serve for more than 100 years in certain soil reinforcement applications. Even so, bio-degradable natural geotextiles are intentionally manufactured to have kind of short period of life. They are generally used to prevent or control soil erosion until vegetation can become properly established on the ground surface.
Synthetic Fibers: There are four main synthetic polymers polypropylene, polyester, polyethene and polyamide; these are most widely used as the raw material for synthetic geotextiles also called geo-synthetics. The oldest synthetic fiber of these is polyethylene, which was discovered in by ICI. Another group of polymers with a long production history are polyamides, the first of which was discovered in . The next oldest of the four main synthetic polymers applicable to geotextiles is polyester fiber, widely used for manufacture geotextiles and it was announced in . The most recent polymer family applicable to geotextiles to be developed was polypropylene discovered in .
Characteristics of Geo-textiles
Mechanical Properties:
PropertyValue RangeCompressibilityNil to highTensile Strength (grab)0.45-4.5 kNTensile Strength (wide width)9-180 kN/mConfined Tensile Strength18-180 kN/mSeam Strength50-100% of tensileCycle Fatigue Strength50-100% of tensileBurst Strength350- k paTear Strength90- NImpact Strength14-200 JPuncture Strength45-450 NFriction Behavior60-100% of soil frictionPullout Behavior50-100% of geotextile strengthHydraulic Properties:
PropertyValue RangePorosity (nonwovens)50-95%Present Open Area (wovens)Nil to 36%Apparent Opening Size (sieve size)2.0 to 0.075 mm (# 10 to # 200)Permittivity0.02-2.2 s-1Permittivity Under Load0.01-3.0 s-1Transmissivity0.01 to 2.0 x 10-3m2/minSoil Retention: turbidity curtainsMust be evaluatedSoil Retention: silt fencesMust be evaluatedEndurance Properties:
PropertyValue RangeInstallation Damage0.70% of fabric strengthCrepe Responseg.n.p. if<40% strength is being usedConfined Creep Responseg.n.p. if<50% strength is being usedStress Relaxationg.n.p. if<40% strength is being usedAbrasion50-100% of geotextile strengthLong-term Cloggingm.b.e. for critical conditionsGradient Ratio Cloggingm.b.e. for critical conditionsHydraulic Conductivity Ratio0.4-0.8 appear to be acceptableDegradation Properties
PropertyValue RangeTemperature DegradationHigh temp. accelerates degradationOxidative Degradationm.b.e. for long service lifetimesHydrolysism.b.e. for long service lifetimesChemicalg.n.p. unless aggressive chemicalsRadioactiveg.n.p.Biologicalg.n.p.Sunlight (UV)Major problem unless protectedSynergistic Effectsm.b.e.General AgingThe actual record to date is excellent[g.n.p. = Generally Not Performed and m.b.e. = Must Be Evaluated]
Functions of Geotextiles
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Filtration: Filter layers of geotextiles generally trap solid material and allow liquid material to pass almost freely perpendicular to the plane of the filter. Geotextiles maintain soil balance that allows adequate fluid flow while reducing soil erosion. It differentiates between mechanical strength (soil holding capacity) and hydraulic filter performance with the aim of achieving water extraction at minimum pressure loss. Mechanically bonded nonwovens are particularly suitable for this function, provided the thickness of the nonwoven is at least 30 times larger than the selected opening size.
Drainage: Drainage is the removal process of precipitation, groundwater and other liquid or gaseous substances. Dense Non-Woven Geotextile provides an opportunity for water flow through the plane three-dimensionally. Drainage systems are provided as composites consisting of at least one filtering layer and one percolation layer. Filter geotextiles are placed to transmit shear stress to the percolation layer to allow long-term drainage performance.
Separation: Geotextiles separate adjacent soil types or prevent fill material from mixing. These geotextile products are used in the form of durable, strong nonwoven or woven fabrics and composites made of synthetic raw materials capable of withstanding high loads. Mechanically bonded nonwovens are particularly suitable for this task as they adapt very well to irregular subsoils and soft soils due to their high expansion capacity.
Protection: Geo-membranes, coated and non-coated structures need to be protected from mechanical damage. Corrosion due to sharp edges of subsurface or fill material will occur if there is no protective layer. Nonwovens and composites are used as protection against this mechanical erosion. Thick mechanically bonded nonwovens act as very good protective layers. Secutex® PP nonwovens are used as the sole protective layer for geomembranes.
Reinforcement: Geotextiles, geogrids and composite materials are placed under or between soil layers for the purpose of soil reinforcement to increase tensile strength and simultaneously improve mechanical properties. These materials are used for soils with a poor load-bearing capacity based on the &#;reinforced soil&#; principle. Mostly geogrid and oven elements are used as reinforcement. Reinforcing elements, where the reinforcing elements are made of slit film yarns (e.g., woven) and polymer ribs with rigid crossing points.
Sealing: Sealing is essential for environmental and groundwater protection, the application of geotextile as a liquid barrier is used for road rehabilitation, it blocks the vertical flow of water within the pavement structure. Geomembranes of different thicknesses depending on different purposes, mainly used as liquid and gas barriers in landfills, tunnel construction and hydraulic engineering. And geomembranes made of different polyethene formulations (e.g., different densities) are used in these areas. Geomembranes are typically over 1.0 mm thick and are installed and welded together by authorized installers. 0.3 mm to 1.0 mm thick plastic sheet can be used in areas where stress is low.
Erosion Control: Three-dimensional geosynthetics and composite materials prevent erosion of soil particles by water and wind. In nature, it is the roots of plants that prevent soil erosion. The natural structure of plant root layers takes several years to develop, which is easily accomplished by using erosion-control matting or netting. Erosion of river or embankment slopes can be easily prevented with the help of various mesh structures.
Applications of Geo-textiles
Geotextile products are used in various constructional works, which increase the strength of weak & soft soils and prevent erosion, also enabling construction in the areas that were previously unsuitable. Geotextiles are ideal materials for many infrastructure works, such as:
Sustainable Geo-Synthetics:
Most geosynthetic products contribute to the long-term stability of the soil structure so that the products can be used for long-term performance with little modification, while the demand for biodegradable products with an emphasis on planting and environmental compatibility is also increasing. Therefore, sustainable geosynthetics are classified as &#;ordinary geosynthetics&#; and &#;green geosynthetics&#;.
First, environmental adaptive geosynthetics, which we previously mentioned as &#;general geosynthetics&#;, have not changed much in the last 20 years but have created a paradigm of composite products using high-performance fibers with the keyword of diversity. Environmentally adapted geosynthetics can be introduced as &#;ordinary geosynthetics&#;, which will be used to reinforce ground structures. In other words, general geosynthetics is a product that requires a high resistance to instantaneous loads from the outside and also needs a hybrid function that combines the reinforcement, protection and blocking functions that are the basic and major functions of geotextiles. Since natural fibers have the advantage of being eco-friendly materials, the utility of geotextiles as raw materials such as various types of cotton, jute, coir and straw has started to re-emerge in recent years. However, since it is not widely used and cannot be mass-produced compared to synthetic fibers, it has difficulty generating demand. Some of them use natural geotextiles as slope stabilization, erosion prevention and drainage, but there is no major change here.
On the other hand, polyolefins and polyesters are the most commonly used synthetic polymer materials and polyurethane, carbon & glass fiber polymers are very limited. Since these polymer materials used in the manufacture of geosynthetics are often used in large quantities at low cost. In general, manufacturing high-performance geosynthetics increases production costs, which are economically expensive. In other ways, if the performance is the same, a product with the lower cost of production is economically advantageous. Considering this, geosynthetics using recycled polymer materials can be considered, but the disadvantages of reduced performance compared to geosynthetics using virgin polymers without recycling become an issue.
Second, &#;green geosynthetics&#; refers to products that have sustainable degradable geosynthetic fibers and environmental pollution prevention and recovery functions that do not imply the long-term implementation of primary functionality in terms of environmental friendliness. For slope stabilization/protection fields requiring eco-environmental properties, mesh-type geocells using biodegradable resins are applied in slope vegetation, river maintenance, eco-slope composition, garden-based layers, landfill slopes and waterproofing protection. This reflects the demand for eco-environmental geosynthetics. In the case of fiber, &#;biodegradability&#; means decomposition by microorganisms or bacteria in the soil, which is a geotechnical structure, and the initial performance gradually decreases during the service period.
Bangladesh is a densely populated, predominantly riverine lowland country in South Asia with 580 kilometers of coastline in the northern littoral region of the Bay of Bengal. Since our country has a lot of low land, geotextile can be the best solution in this case. It is a segment of technical textiles used for special purposes. Geotextiles are porous textile structures made of polymeric materials and are mainly used in the civil engineering and construction sector. According to the period of use, there are three types of geotextiles they are first generation, second generation and third-generation. Although the production of geotextile in Bangladesh started a long time ago, its use in various construction sectors has become quite popular in the last few years. During the construction of various Highways, Bridges and Dams such as Bangabandhu Bridge, Padma Multipurpose Bridge, Dhaka-Sylhet Highway, Dhaka-Aricha Highway, DND Dam, Gomti Dam, Tista Barrage, Teknaf Coastal Works, Airport etc., geo-textiles are used for slope stability, soil erosion control and land filling. DIRD Group started manufacturing geosynthetics in Bangladesh in , currently many textile industries in Bangladesh are producing geotextiles commercially for our domestic use and for export. Some of the major geotextile manufacturing companies in our country are-
The Geotextile manufacturing industry has huge scope in Bangladesh. Every year the Bangladesh government allocates a huge budget for the construction or renewal of roads, bridges and culverts in rural areas. If geotextiles are used in these projects, the life span of those roads/culverts will be many times longer than before. Also, there are many ETP plants installed in Bangladesh but none of them can handle their sludge effectively, the main problem is the separation of solids from liquid. The use of Geo bags can be an excellent, simple and environmentally friendly way to solve this problem. Also, City Corporation people can also use Geo bags while cleaning silted drains to separate solids from liquids. South of Noakhali and Lakshmipur there are many low-lying lands where the lands are not suitable for cultivation or are only suitable for one season and are underwater for the rest of the year. Geo-bag dams made from slurry can be used to make these lands suitable for year-round cultivation. Soil erosion control can be another very important application of geotextiles. Every year many riverside residents in Bangladesh suffer from erosion problems resulting in total loss of their land and property. Geotextiles can be the simplest and most cost-effective solution to this humanitarian problem of mass destruction.
In some applications, such as erosion control Jute Geo-textiles can be used effectively, we need geotextile for a limited period of time in terms of erosion control and after a certain period, it completely degrades which then acts as a fertilizer. Also, for the advancement of the geotextile sector, we need to master the skills of manufacturing fabrics of various specifications and properties of woven, and non-woven. The use of jute in the production of geotextiles is a recent and emerging technology in the field of geotechnical and bio-engineering. All kinds of jute products can be used as geo-textiles. But one of the disadvantages of jute products is fast biodegradability. But their lifespan can be extended up to 20 years by various chemical treatments. Thus, designed biodegradable jute geo-textiles with specific stiffness, porosity, permeability, transmissibility as per requirement and location specificity are possible. Some of the important advantages of Jute Geotextiles are-
Global Geotextile Market Size:
Geotextiles are widely used in construction due to their performance and cost-effectiveness. Innovations are constantly coming to enhance the performance of geotextiles. According to experts, geotextiles will account for 1% of the total global technical textile market, which will be around USD 1.27 billion. The global geotextile market size was USD 8.04 billion in . Fortune Business Insights forecasts that the market will grow from USD 8.47 billion in to USD 12.92 billion in and exhibits a CAGR of 6.2% during the forecast period. The world is experiencing lower-than-expected demand compared to the pre-Covid-pandemic period. Based on their analysis, the global geotextile market declined by 1.44% in compared to . However, increasing demand for high-performance and functional textiles along with increasing development in the construction industry in the post-pandemic period is a primary factor driving the market growth of geotextiles. They are widely used for soil improvement on which pipelines, roads, soil retention structures and dams are constructed. Some prominent players in the geo-textiles market include:
Conclusion:
Geotextiles, an important member of the geosynthetic family, are widely used for civil engineering and construction applications. The engineering design of these geotextiles depends on factors such as the appropriate selection of material fibers/filaments, manufacturing techniques and durability properties. The concept of &#;hybrid&#; geotextiles can meet some of these requirements by using both natural and synthetic fibers in optimal proportions. Similarly, the choice of manufacturing technique should be based on the properties of the geotextile that meet the requirements of the desired applications through its performance. Therefore, the most important step towards geotextile selection should be based on the &#;design by function route&#;. This step can be successfully achieved with a multidisciplinary approach based on the combined efforts of various disciplines including textile, civil, chemical and material sciences. Despite the huge demand for geotextiles in the world, due to some limitations, we are not able to exploit the opportunity to export them in large quantities. The main reasons for this are lack of product variety, lack of high-performance textile production and use of outdated machinery, low investment and lack of research, administrative inefficiency etc. To accelerate exports, the government should recognize geotextiles as a growth and economic sector and set up an office/department under the Ministry of Textiles headed by textile engineers.
Reference:
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