Technical Shiksa

GEOTEXTILES AND ITS APPLICATION

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 GEOTEXTILES AND ITS APPLICATION

As we know, the prefix of geotextile, geo, means that earth and therefore the ‘textile’ means that material. Therefore, consistent with the definition of the geotextile is outline as:-

“A porous geosynthetic comprised exclusively of textiles. Geotextiles square measure used with foundation, soil, rock, earth, or the other geotechnical engineering-related material as AN integral a part of human-made project, structure, or system.”

The ASAE (Society for Engineering in Agricultural, Food, and Biological Systems) defines a geotextile as a “fabric or artificial material placed between the soil and a pipe, gabion, or holding wall: to reinforce water movement and retard soil movement, and as a blanket to feature reinforcement and separation.” A geotextile ought to carries with it a stable network that retains its relative structure throughout handling, placement, and long service.

There square measure some attention-grabbing business aspects associated with geotextiles that square measure specific to the trade. for instance, convenience should be thought-about within the light-weight of the acute size vary of operations into that geotextiles square measure incorporated. regarding common fraction of all geotextiles square measure utilized in little batches of 3 rolls or less, however a considerably giant proportion square measure utilized in terribly giant comes incorporating many thousands of sq. metres. offer should so be on the market on involve one or 2 rolls from native stock and, at the same time, should be on the market through agents or directly from the manufacturer in giant quantities over a brief area.

Typical geosynthetic material

TYPES OF GEOTEXTILES

Geo textiles essentially represent four classes –

Non-woven

RAW MATERIALS

The four main chemical compound families most generally used because the staple for geotextiles are:

1.Polyester
2.Polyamide
3.Polypropylene
4.Polyethylene

The two most common fiber polymers use in geotextile manufacturing are polypropylene and polyethylene, while polyester is almost always chosen when high strength is require. Although some other polymers offer higher strength, manufacturers typically avoid them due to limited availability in large volumes and high cost. Polypropylene and polyethylene offer the best balance between cost and performance, but polyester remains the optimal choice due to its superior strength and chemical resistance.

When evaluating geotextile polymers, engineers must consider the polymers as they are actually manufactur and use, not in their chemically pure forms. For example, raw polyethylene appears as a colorless, clear material that degrades quickly under light. However, geotextile applications typically use a black, carbon-filled version of polyethylene that includes UV stabilizers, making it one of the most UV-resistant polymers available.

Although nylon (polyamide) is a common fiber-forming polymer in textiles, it sees limited use in geotextiles due to its relatively high cost and poorer performance compared to polyester. Some woven materials incorporate nylon only in the weft direction (fill yarn), where its properties are less critical. Nylon offers good abrasion resistance but tends to soften when exposed to water, limiting its usefulness in geosynthetics. Manufacturers in Japan and the U.S. have used polyvinylidene chloride fibers in select products, but this fiber remains uncommon in Europe.

PROPERTIES OF GEOTEXTILES

Geotextiles must meet three critical performance requirements:

  1. Mechanical Response

  2. Filtration Ability

  3. Chemical Resistance

These functional properties depend on a combination of the polymer type, fiber structure, and textile construction method.

1. Mechanical Response

A geotextile must perform under stress and withstand harsh conditions. Engineers select the textile based on anticipated stress conditions and numerical design criteria. The textile must absorb expected loads over the structure’s service life without exceeding predetermined strain limits.

Engineers use stress–strain curves to classify geotextiles:

2. Filtration Ability

Unlike typical filters that remove suspended solids, geotextile filters aim to retain soil structure while allowing water to pass. A successful geotextile prevents soil surface erosion, not just particle migration.

If water flows along the interface between the geotextile and the soil and carries particles in suspension, it may clog the geotextile and cause failure. In practice, the soil often forms its own filter layer when paired with a properly selected geotextile—as long as the external soil surface remains intact. This process enables water to pass through without transporting solids.

3. Chemical Resistance

Geotextiles rarely encounter highly aggressive chemical environments, but exceptions include:

While UV radiation can degrade most polymers, manufacturers reduce this risk by incorporating UV stabilizers and carbon black. These additives significantly enhance the long-term durability of geotextiles exposed to sunlight.

MECHANICAL PROPERTIES

The weight or space density of the material is Associate in Nursing indicator of mechanical performance solely inside specific teams of textiles, however not between one kind of construction and another. as an example, inside the general vary of needle punched continuous filament polyester materials, weight can correlate with tensile stiffness. However, a woven material with a given space density can virtually definitely be a lot of stiffer than a similar weight needle punched structure. Clearly the development controls
the performance. Therefore, it’s not possible to use weight alone as a criterion in specifying textiles for engineering science use. However, together with alternative 364 enchiridion of technical textile.

Different stress–strain curve shapes exhibited by the 3 main varieties of geosynthetic construction.

(a) Geogrids absorb the obligatory stresses instantly, giving a high initial modulus. Later, the curve flattens.

(b) woven materials exhibit initial straightening of warp fibres that produces a coffee initial modulus. Later the modulus will increase because the straightened chemical compound fibres take the strain directly.

(c) Nonwovens provides a curvili close to curve, as a result of extension is primarily resist by straightening and realignment of the random fibre directions.

The breaking strength of a customary breadth of cloth or ‘ultimate strip tensile failure strength’ is universally quote within the manufacturers’ literature to explain the ‘strength’ of their textiles. Again, this can be of terribly restrict use in terms of style.
No styleer really uses the failure strength to develop a design. Rather, a strength at a given tiny strain level are the planning demand. Therefore, the tensile resistance or modulus of the textile at say, 2%, 4%, and 6 June 1944 strain is far a lot of valuable. Ideally, continuous stress–strain curves ought to be provided for engineers, to alter them to style stress resisting structures properly.

Stress–strain curves, as shown on top of, could comprise a high strain sector, contributed by the textile structure straightening out, and a coffee strain sector, contributed by the straightened chemical compound taking the strain. Of course, the mechanical performance of the common geotextiles are less because the close temperature rises. as a result of engineering sites area unit exposed to temperatures
varying from -20 °C to 50°C, this could have necessary consequences throughout installation and use.

Creep will cause the physical failure of a geotextile if it’s command below too high a mechanical stress. it’s been found that in sensible terms, each polyester and polythene can stabilize against creep if stress levels are often maintained at a sufficiently
low level.

Although polypropene doesn’t appear to stabilize at any stress level, its creep rate is thus low at tiny stresses that a ‘no creep’ condition is also thought-about to exist in apply.

Approximate Limits of Creep Resistance in Geosynthetic Polymeric Structures

Engineers define the “no-creep” condition for any geosynthetic polymer as a specific elongation percentage relative to the material’s ultimate load-bearing capacity. This value indicates the safe long-term stress level beyond which creep failure begins to accelerate.

For example, if a polyester geotextile has a final strength of 100 kN/m, it should not experience long-term loading above 60 kN/m. Applying stress beyond this threshold significantly increases the risk of early creep failure. The higher the applied stress exceeds this limit, the faster the material will deteriorate.

. Figure 14.3 shows the safe loading limits for many usually used geotextiles.

Wing tear, grab tear and puncture resistance tests is also valuable as a result of they simulate on-the-spot harm situations like boulder dropping and direct over-running by machines. These tests area unit developed in customary type in a very range of nations,
with the quality geosynthetic take a look at specification within the GB being SB 6906 that contains tests for

1 tensile take a look a ting by suggests that of a large strip test
2 pore size testing by dry sieving
3 water flow testing traditional to the plane of the textile
4 puncture resistance testing
5 creep testing
6 perforation susceptibleness (cone) testing
7 water flow testing within the plane of the textile
8 testing of sand/geotextile resistance behaviour.

While not commonly a part of the mechanical necessities of a textile, the strength of joints between sheet edges is a very important side of geotextile performance.

When birthing textiles on soft ground for supporting embankments, parallel sheets of textile ought to be seamed along in order that they are doing not separate underneath load. The strength of such seamed joints depends critically on the enduringness of the stitching thread. seldom can the seamed joint exceed half-hour of the yarn final enduringness.
Research and field apply have shown that the strength of a seamed joint depends additional upon the purpose and tension of the stitching thread, the sort of {stitching} stitch for various geosynthetic chemical compound constructions. and therefore the reasonably textile lap than the strength of the textile.

An incorrect however common idea of joint ‘efficiency’ has developed that expresses the strength of a seamed seam as a share of the textile strength. In fact, comparatively weak textiles are often seame specified the joint is as sturdy because the textile, therefore giving a 100 percent potency.The stronger the textile, the less is that the relative strength of the seamed joint, resulting in falling efficiencies with stronger materials.Thus it’s affordable to request a seventy fifth economical seamed joint if the textiles being joined square measure comparatively weak, say twenty kN final strength, however it’d be not possible to attain with a textile of say 600 kN final strength.

unfortunately, stronger geotextiles often require joining to provide adequate support for embankments and similar structures. Engineers can use single-component adhesives, which set upon exposure to atmospheric moisture, to form these joints. These adhesives can create bonds as strong as the textile itself, even for high-strength materials.

Although adhesive bonding methods show great promise, ongoing research is still necessary to refine their application techniques. In the future, these methods will likely see wider adoption. Beyond tensile testing, the field urgently needs new testing methods that accurately describe how geotextiles behave under confinement—both within and due to surrounding soil masses. Existing textile test standards fail to capture this behavior accurately. Researchers have begun to investigate these issues, but current findings are still too limited to support detailed theoretical analysis.

Filtration Properties

Filtration remains one of the most critical functions of geotextiles in geotechnical engineering. It accounts for the largest application area, with uses ranging from ditch linings and road bases to waste containment systems, basement drainage, hill stabilization, and marine defenses. Among all geotextile applications, reinforced soil masses are the only exception where filtration may not offer a direct benefit.

In almost all other scenarios—such as drains, access roads, riverbanks, and infrastructure runoffs—geotextiles serve a primary or secondary filtration role.

The porosity of a geotextile can vary widely, depending on its textile construction. National and international standards now define how to measure porosity, usually in the cross-plane direction (perpendicular to the surface), but also in the in-plane direction, where it is referred to as transmissivity.

In geotechnical works, it is essential to allow free water flow through the geotextile, preventing excess water pressure from building up within the soil structure. This ensures long-term stability and effective drainage in engineering applications

The porosity constant may be a variety whose worth describes the porosity of the fabric involved, taking under consideration its dimension within the direction of flow; the units square measure rationalised in metres per second. Effectively the constant may be a speed, indicating the flow speed of the water through the textile. Usually, this can be of the order of zero.001ms-1.A normally such as take a look at measures a directly determined throughflow rate, that several feel is additional sensible than the porosity coefficient; this can be the degree throughflow in litres per centare per second at one hundred millimetre head of pressure.

Engineers additionally use a constant known as the permittivity, that defines the theoretical porosity regardless of the thickness of the material

Filtration Mechanism 

Filtration occurs when the geotextile remains in close contact with the soil, preserving the structural integrity of the exposed soil surface through which water flows. Within the first few millimeters of soil, an internal soil filter zone forms. After a brief phase of piping, the system stabilizes and effective filtration takes place.

As mentioned earlier, geotextiles often achieve filtration by promoting the formation of the soil filter itself. This process creates a solid-soil medium, allowing fluid to pass through while maintaining the soil matrix.

However, some specialized cases demand filtration under suspension conditions—for instance, in tailings lagoons from mining operations or industrial slurries, where water must be extracted from suspended solids.

In such environments, standard geotextiles perform poorly. Experimental studies suggest that using a composite system of two different textiles significantly improves filtration. The most effective configuration combines a smooth woven geotextile layered over a thick needle-punched nonwoven fabric. Placing the woven fabric between the nonwoven layer and the suspension optimizes the filtration effect without blocking the flow.

It seems that the woven material acts as a ‘shield’, protective the nonwoven from the liquid and emulating a soil surface, thus
permitting the nonwoven to operate additional effectively as a filter.The emptying result of the underlying nonwoven additionally presumably acts to induce high hydraulic gradients that, reciprocally, assist the woven to operate.

It appears that the plain-woven cloth acts as a ‘shield’, protective the nonwoven from the liquid and emulating a soil surface, thus
permitting the nonwoven to operate additional effectively as a filter.The evacuation result of the underlying nonwoven conjointly probably acts to induce high hydraulic gradients that, reciprocally, assist the plain-woven to operate.

The procedure for matching a textile to the soil, so as to attain stability underneath tough hydraulic conditions, is to use a textile whose largest holes square measure equal in diameter to the biggest particles of the soil

Filtration Pore Size and Its Impact

The D90 represents the particle diameter at which 90% of the soil particles are smaller. By convention, this serves as a reference for filtration design. Similarly, the O90 refers to the pore size of a geotextile such that 90% of the pores are smaller than this dimension.

Even under optimal conditions, if the O90 pore size exceeds five times the D90, piping is likely to occur. To prevent this, engineers reduce the O90 value closer to D90 as the ground conditions worsen and hydraulic stress increases.

Chemical Resistance of Geotextiles

Despite the complex chemistry involved in fiber degradation, four main agents drive deterioration in geotextiles:

  1. Organic Agents:
    Microorganisms and soil fauna can indirectly damage geotextiles. Although animals do not typically feed on geotextile material, they may damage it by burrowing. Microorganisms can colonize the fibers and produce harmful byproducts that gradually degrade the material. The most challenging environment for geotextiles is the surf zone, where aerated and moving seawater creates both biological and mechanical stress.

  2. Inorganic Agents:
    In most cases, geotextile polymers remain chemically inert. However, extreme pH environments may cause degradation. For instance, polyester becomes vulnerable at pH levels above 11, such as in the presence of cement-setting byproducts. Although such conditions are rare, they are easily identified.

  3. Light Exposure:
    UV light can degrade geotextile materials over time. Manufacturers address this by incorporating UV stabilizers or carbon black to improve resistance to sunlight.

  4. Aging (Time-Related Degradation):
    Prolonged exposure to environmental conditions can alter the polymer structure, affecting performance over time.

Filtration Failures 

Geotextiles can fail to perform filtration if biological growth clogs the pores or if mineral-rich water causes chemical precipitation. In particular, drainage systems installed near old mine workings often encounter water saturated with iron compounds. These compounds precipitate rapidly and block geotextile or granular filters, reducing their effectiveness.

Ultraviolet light can deteriorate geotextile fibres if exposed for important periods of your time, however laboratory testing has shown that fibres can deteriorate on their own with time, notwithstanding keep underneath dry dark cool conditions in a very laboratory.Therefore, time itself could be a damaging agent as a consequence of close temperature and thermal degradation, which can deteriorate a geotextile by associate unknown quantity

APPLICATIONS

1.Drainage (fluid transmission)

Normally the strength of soil is decided by its water content; because the water content decreases its strength will increase and the other way around. A geotextile will convey fluids or gases among the plane of the geotextile to associate egress purpose. The system permits dissipation of excess pore water pressure, so consolidation will happen and therefore the soil strength is hyperbolic. the speed of dissipation of excess pore water pressure will be increased by victimisation temporary drains within the soil in order that the evacuation path is reduced .This type of drain is merely needed to perform for a restricted fundamental measure, till consolidation has taken place

2.Filtration

A geotextile acts as a filter by allowing the flow of liquid and gases, however preventing the passage of soil particles which may cause settlement because of loss of ground. The pore size among the geotextile is chosen to avoid interference, blazing and preventative.

Ground drains square measure wont to prevent/intercept water flow, ordinarily to cut back the chance of an increase in pore water pressure. usually these drains square measure vertically sided trenches, lined with a geotextile so crammed with coarse gravel. Initial loss of soil particles are going to be high adjacent to the geotextile.

This causes a zone (in the remaining soil particles) to bridge over the pores within the geotextile and retain smaller particles, that successively retain even smaller particles. so a natural hierarchal filter is created which can forestall extra washout of fine particles, when that the geotextile becomes more-or-less redundant. If the geotextile wasn’t wont to encapsulate the coarse granular evacuation material, an excessive amount of wash-through of particles.

3.Separation:-


A geotextile acts as a extractor by preventing the intermixing of coarse and fine soil materials while permitting the free flow of water across the geotextile. for example, once a geotextile is placed between the under soil and therefore the granular sub-base of associate caliche-topped road, it prevents the combination from being punched down into the soil throughout initial compaction and after from the dynamic loading of car axles.

4.Erosion control/absorption

A speedily developing space for geotextiles is within the erosion management business wherever they’re utilized for short effects.This usage differs from the opposite applications of geotextiles therein they’re set on the surface and not buried within the soil. the most aim is {to management|to regulate|to manage} erosion while serving to to determine vegetation which can control erosion naturally.

The geotextile is then surplus to necessities and might degrade, enriching the soil. Geotextiles will scale back runoff, retain soil particles and defend soil that has not been vegetated, from the sun, rain and wind. they’ll even be wont to suppress weeds around new planted trees.Erosion management will be applied to riverbanks and coastlines to stop undermining by the ebb and flow of the tide or simply by wave motion.

5.Reinforcement:-

Due to their high soil cloth friction constant and high end duringness, significant grades of geotextiles square measure wont to reinforce earth structures permitting the employment of native fill material.This is the synergistic improvement within the total system strength created by the introduction of a geotextile into a soil and developed primarily through the subsequent 3 mechanisms:

One, lateral restraint through surface friction between geotextile and soil/aggregate. Two, forcing the potential bearing surface failure plane to develop at alternate higher shear strength surface. And three, membrane variety of support of the wheel masses

  Mechanical Hydraulic Long-term performance
Base failure Shear strength of bonding system Hydraulic boundary conditions Chemical and decay resistance
Top failure Tensile strength of geotextileGeotextile/ soil friction Hydraulic boundary conditions Chemical and decay resistance
Slope failure Tensile strength of geotextileGeotextile/ soil friction Hydraulic boundary conditions Creep of the geotextile/ soil systemChemical and decay resistance

This is the synergistic improvement within the total system strength created by the introduction of ageotextile into a soil and developed primarily through the subsequent 3 mechanisms: One,lateral restraint through surface friction between geotextile and soil/aggregate. Two, forcing the potential bearing surface failure plane to develop at alternate higher shear strength surface. And three, membrane variety of support of the wheel masses.

MARKET ACTIVITY

To say that the market activity of geo synthetics within the geotechnical, transportation, and environmental areas is robust is in spades an underestimation. to get AN insight into the vitality of geosynthetics

CONCLUSION

Geotextiles square measure a part of a wider cluster of applied science membranes referred to as geosynthetics.

They are extraordinarily various in their construction and look. However,they are usually made of a restricted variety of polymers (polypropylene,polyethylene and polyester), and square measure largely of 5 basic types: plain-woven, heatbonded, needlepunched, unwoven and direct soil mixed fibres.

The physical properties of this various cluster of product vary consequently, with final strengths reaching up to 2000 kNm 1, however normally between ten and two hundred kNm-1. final strains vary up to quite 100 percent, however the usable vary for engineers is mostly between three and 100 percent.

Similarly, the filtration potential and porousness of various geotextiles vary hugely. Geotextiles square measure employed in applied science earthworks to strengthen vertical and steep banks of soil, to construct firm bases for temporary and permanent roads and highways, to line ground drains, in order that the soil filters itself and prevents soil from filling up the drainpipes and to forestall erosion behind rock and facing on watercourse banks and therefore the coast.

They have been developed since the middle 1970 s, however the appearance of unwoven and composite materials has crystal rectifier to a revival in a veryttempts to boost textile construction in a designed fashion. higher physical properties will be achieved by exploitation quite one material and by utilizing the simplest options of every.

One, lateral restraint through interfacial friction between geotextile and soil/aggregate. Two, forcing the potential bearing surface failure plane to develop at alternate higher shear strength surface. And three, membrane type of support of the wheel loads

This is the synergistic improvement in the total system strength created by the introduction of ageotextile into a soil and developed primarily through the following three mechanisms: One,lateral restraint through interfacial friction between geotextile and soil/aggregate. Two, forcing the potential bearing surface failure plane to develop at alternate higher shear strength surface. And three, membrane type of support of the wheel loads.

 

  MARKET ACTIVITY

To say that the market activity of geo synthetics in the geotechnical, transportation, and environmental areas is strong is decidedly an understatement. To obtain an insight into the vitality of geosynthetics

CONCLUSION

Geotextiles are part of a wider group of civil engineering membranes called geosynthetics.

They are extremely diverse in their construction and appearance. However,they are generally made from a limited number of polymers (polypropylene,polyethylene and polyester), and are mostly of five basic types: woven, heatbonded,needlepunched, knitted and direct soil mixed fibres.

The physical properties of this diverse group of products vary accordingly, with ultimate strengths reaching up to 2000 kNm-1, but commonly between 10 and 200 kNm-1. Ultimate strains vary up to more than 100%, but the usable range for engineers is generally between 3 and 10%.

Similarly, the filtration potential and permeability of different geotextiles vary enormously. Geotextiles are used in civil engineering earthworks to reinforce vertical and steep banks of soil, to construct firm bases for temporary and permanent roads and highways, to line ground drains, so that the soil filters itself and prevents soil from filling up the drainpipes and to prevent erosion behind rock and stone facing on river banks and the coast.

They have been developed since the mid 1970 s, but the advent of knitted and composite fabrics has led to a revival in attempts to improve textile construction in a designed fashion. Better physical properties can be achieved by using more than one fabric and by utilizing the best features of each.

MCQ

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