What is nonwoven geotextiles?
Nonwoven geotextiles are permeable geosynthetics made of nonwoven materials used along with geotechnical material (soil, rock, etc.) on the integral part of a civil engineering projects. It’s produced mechanically or chemically or by heat-bonding fibres together to form stable fibre network. Nonwoven geotextiles are frequently made polymers from synthetic material like polypropylene, polyethylene, polyamide, polyester, etc. The polypropylene fibre dominates in the geotextile application, cause of its low cost, low specific gravity and strength. But nonwoven geotextiles also made from natural fibres (jute, sisal, coir, etc).
Why use nonwovens in geosynthetics?
In geotextiles, geosynthetics material specially nonwovens are used in the civil engineering field. Nonwovens materials are used to separation, reinforcement and as filters in the construction.
Nonwovens in geotextiles laid to form a roll and are light, easy to handle, despite its strength and toughness.
It has higher flexibility and movement than woven geotextiles. As a result, it is ideal for use in separation. The thickness and puncture resistance of nonwoven geotextile provides cushioning and protection to geomembranes in the areas of landfill, pond, drainage, dams, river canals and costal work, embankments, and mining design.
Nonwoven geotextiles are also used in applications where filtration and drainage are required because of its smaller opening sizes and ability to filter smaller particle sizes which allowing water to pass. It is ideal for separation in paving applications in both asphalt and concrete roadways. In concept of barrier application, the nonwoven material can act as a barrier to water infiltration.
Non-woven geotextiles satisfy the qualities needed for demanding environments. Cause, it is strong, tear and puncture resistance, lightweight and tolerant to fluctuations in the temperature fluctuation.
Quick developments in infrastructure is led to huge demand for nonwovens geotextiles in water conservancy, drainage, dams, river canals and costal work, embankments, road, highway, motorways, railway track, airfields, sports fields, and many sustainable other projects. The unique flexibility of nonwovens used in geotextile to makes suitable for use in securing landfill infrastructure and in drainage, in filtration applications.
Application of nonwoven geotextiles:
Nonwoven geotextiles manufactured from either continuous filaments or staple fibres. Continuous filaments and staple fibres are used to separation, reinforcements, filtration, drainage, moisture barrier, etc for roads and railways off shore land reclamation, road side, rail side, river and canal banks and embarkments. Non-woven have some unique functions in geotextiles include filtration, drainage, separation, reinforcement, and erosion control, etc.
These key functions may be defined as follows:
- Filtration: Nonwovens materials are used to retain fine soil particles. This technique prevents fine particles from being leached and draining elements. It is probably the most common technique in geotextiles which invented in the mid-1960s.
- Separation: Nonwovens are used to separate two layers of soil, which have different particle size distributions. It helps to prevent fine-grained subgrade soils from pumping up into permeable granular road bases. It prevents the two adjacent layers from mixing of a structure. Nonwoven separator is necessary to ensure the long-term performance of the structure. The applications in roads, railroads, walls, dams, embarkments, barriers, etc; in all of these, nonwovens are used in geotextile with separation as its primary function.
- Drainage: Geotextiles are used as a passive element to transport liquids elements or gas elements. The drainage functions are done by the geotextile alone.But often it’s combined with other elements like: drainage core, perforated pipes, etc. Needle-punched geotextiles are used combined with other materials to increase drainage capacity. This combination is referred to as drainage geo-composites.
- Reinforcement: Geotextile is used in reinforcement to increase the load-bearing capacity of soft soils. Reinforcement is a common application used in the field of road engineering.Nonwovens can reduce the level of stress in the foundation soil. Because, horizontal shear stresses are mobilized by vertical loads. This function of nonwoven spreads the load over a large area and decreases its intensity. The ultimate purpose is to be reduced the vertical stress and provide less possibilities from failure.
- Liquid barrier: The open structure of nonwoven geotextiles allows itself to be soaked with combined with clay particles that enter open spaces within the structure of the geotextile to prohibit the passage of liquids.
- Erosion control: Nonwoven fabrics acts both as a separator and as a drainage layer. But when its basic function is to aid in erosion control it is placed in special category. A much bigger possible market for nonwoven geotextiles exists in the soil erosion control.
According to the European standards, requirements of geotextiles in the application areas are defined by: roads, railways, earthworks, retaining walls, drainage systems, erosion control, dams, canals, underground structures, solid waste disposal, liquid waste containment, etc. The chart below can help you to find the various application area of nonwoven geotextiles:
- Roadway Separation
- Roadway Stabilization
- Temporary Erosion Control
- Permanent Erosion Control
- Geomembrane Liner Protection
- Landfill Leachate Collection
- Landfill Drainage Systems
- Gas Venting
- Cow Carpet
- French Drains
- Filter Fabric
- Geo-membrane Cushion.
- Landscape Fabric
- Pipe Wrap
- Railroad Ballast Separation
- Separation Under Pavers
- Subsurface Drainage
- Trench Drains
- Weed Barrier, etc
Opportunity of Nonwoven Geotextiles:
A special concept of nanotechnology has focused on formulations used to manufacture geotextiles. Separation and filtration are functions widely using geotextiles from nano-clay formulations. Nanofiber is one of the most advanced materials which is designed with geo materials. Advanced geotextile materials which have separation, filtration, and absorption functions which could be developed in the field of geo-environmental applications.
In May 2018, the European Commission released on comprehensive Plastics Strategy report: “The Single-Use Plastics: New Measures to Reduce Marine Litter”. The report proposed new rules to reduce the 10 most found plastic waste items:-
- Cotton buds.
- Cutlery, plates, straws and stirrers.
- Sticks for balloons and balloons.
- Food containers.
- Beverage cups.
- Beverage containers.
- Cigarette butts.
- Plastic carrier bags.
- Crisp packets and candy wrappers.
- Wet wipes and sanitary items.
This ban on the one-time uses of plastics has already impacted the nonwoven geotextile industry. This is EU policy gives opportunity to the textile industry improving on the Non-woven products.
Nonwovens geotextiles also have intensive comparable opportunity with automobiles, aircraft, fighter jet, computers, semiconductors, and heavy machinery industry.
Challenges of Non-Woven Geotextiles:
- Lack of Awareness: Benefits of geotextiles is still unknown to the world. Lacking of marketing and basic knowledge about nonwoven geotextile products is the main challenge to the textile industry.
- Lack of Skilled Workforce: Geotextiles is a highly diversified subject with multiple processes to manufacture various products. These processes require high level of skill sets from workers. But skilled manpower is currently absent in the geotextile field.
- Lack of Researchand Development: Geotextiles industry is facing is the lack of product diversification. It is an innovation intensive field and it focuses on product research anddevelopment. But textile industry has faced lack of research and development.
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Nonwoven geotextile industries sharedspecial heritage on environment. It has grown to present a broad array of engineered-fibre and polymer-based products that are powered by low production cost, innovative, value-added processes, etc. Geotextiles industry reducing the dependence on low cost labour with eco friendly geo materials. As a result, it also has intensive comparable technology with automobiles, aircraft, computers, semi-conductors, and heavy machinery industry. It can be observed that application of nonwovens in geotextiles will make a better world for the up-coming generation. So, textile industry should have to more research and invest on non-woven geotextiles.
- Geotextiles from Design to Applications Edited by R.M. Koerner
- Nonwovens: Process, Structure, Properties and Applications by T. Karthik, R. Rathinamoorthy and C. Praba Karan
- Geotextile: It’s Application to Civil Engineeering – Overview by Dr. Bipin J Agrawal
Author of this Article:
Md Mahedi Hasan
B.Sc. in Textile Engineering
Textile Engineering College, Noakhali.