GEOTEXTILES

Prepared By : 091012 D – J. A. L. Jayasinghe

What is Geotextile?• Geotextile is one of the members of the

Geosynthetic family.• Geosynthetics are the generally polymeric

products used to solve civil engineering problems.

Geo

synt

hetic

s

Geotextiles

Geogrids

Geonets

Geomembranes

Geosynthetic Clay Liners

Geofoam

Geocells

Geocomposites

What is Geotextile?

• Geotextiles (often called “filter fabrics”) are any permeable, textile material used with foundation, soil, rock, earth, or any other geotechnical engineering-related material as an integral part of a man-made project, structure or system.

• Definition of ASTM 4439"A permeable geo-synthetic comprised solely of textiles. Geotextiles are used with

foundation, soil, rock, earth, or any other geotechnical engineering-related material as an integral part of human-made project, structure, or system."

• Definition of ASAE (Society for Engineering in Agricultural, Food, and Biological Systems) “Fabric or synthetic material placed between the soil and a pipe, gabion, or

retaining wall: to enhance water movement and retard soil movement, and as a blanket to add reinforcement and separation."

GeotextilesGeo - Earth

Textile - Fabric

Brief History of Geotextiles

• First applications of geotextiles were woven industrial fabrics used in 1950’s.

• One of the earliest documented cases was a waterfront structure built in Florida in 1958.

• Then, the first nonwoven geotextile was developed in 1968 by the Rhone Poulence company in France. It was a comparatively thick needle-punched polyester, which was used in dam construction in France during 1970.

• The term geotextile was first proposed by Giroud and Perfetti in 1977

Market Trend of Geotextiles

Why?? → large scale infrastructural development going on at a global level.

50% of the market demand ↓

Road industry applications

Growth in world use of geotextilesGlobal market Demand

↓ US $ 6.3 billion by 2017

(Growth expected to come from emerging economies in Asia)

USChina

India

UK Germany

Denmark

Netherland

Market Trend of GeotextilesMajor hubs for geotextile

Netherlands

40%

27%

33%

GeoTextiles Demand by 2017

Asia $2.50USA $1.70Other $2.10

Demand in US $ Billions

Market Trend of Geotextiles

IMPORTANT CHARACTERISTICS OF GEOTEXTILES

Physical Properties:– Weight– Thickness– Stiffness– Density– Specific Gravity

Mechanical Properties:– Tenacity– Tensile Strength– Bursting Strength– Drapability– Compatibility– Flexibility– Tearing Strength– Frictional Resistance

The characteristics of geotextiles are broadly classified as:

IMPORTANT CHARACTERISTICS OF GEOTEXTILES

Hydraulic Properties:– Porosity - ratio of the volume of all the pores in a material to the total volume– Permeability – ability to be penetrated by liquids or gases– Permittivity - ease with which a fluid can move through pore spaces or fractures– Transitivity - ability to hold or contain (as in soil retaining water)– Turbidity/Soil Retention– Apparent opening size ( A.O.S.)

Endurance properties:– Elongation– Abrasion Resistance– Clogging Length & Flow

Degradation Properties:– Biodegradation– Hydrolytic Degradation - degradation

due to constant exposure to water– Photo Degradation– Chemical Degradation– Mechanical Degradation– other degradation occurring due to

attack of rodent, termite etc.

SELECTION OF MATERIAL FOR GEOTEXTILES

Types of Material

Natural

Ramie

Jute

Coir

Synthetic

Polyamide (PA)

Polyester (PET)

Polyethylene (PE)

Polypropylene (PP)

Polyvinyl Chloride (PVC)

Ethylene Copolymer Bitumen (ECB)

Chlorinated Polyethylene (CPE)

Most Commonly

Used

SELECTION OF MATERIAL FOR GEOTEXTILES

• synthetic fibre Usage in Geotextiles• Polypropylene (90%)• Polyester (6%)• Polyethylene (2%)• Nylon (1%)• Other (1%)

THE TYPES OF GEOTEXTILE

In general, the vast majority of geotextiles are made from polypropylene or polyester formed into fabrics as follows:

Geotextiles

Woven

Woven Mono/Multifilament

Woven Slit-filmMono/Microfilament

Woven Fibrillated

Non-woven

Continuous Filament Heat Bonded

Continuous Filament Needle Punched

Staple Needle Punched

Resin Bonded

Knitted

Warp Knitted

Spacer Fabric

Warp Knitted

Weft Knitted

Weft KnittedOther Woven and Non-woven

Combinations

THE TYPES OF GEOTEXTILE• Woven geotextiles:

This geotextile fabric is best used for road construction, with rip rap (loose

stone used to form a foundation for a breakwater or other structure), heavy erosion, embankments, and steep slopes.

• Nonwoven geotextiles:Used for filtration, drainage, reinforcement between soil stone or aggregate and in roads, railways works, erosion prevention and separation.

• Knitted geotextiles: Knitted bags for protection of dam's riverbank etc. Warp knitted fabric of Kevlar yarns used in marine application.Spacer fabrics are mainly used for filtering and drainage applications

Note - Spacer fabrics consist of two covering textiles, which are connected with filaments. The distance between the two layers is exactly defined. Spacers are also called 3D textiles because of their special structure.

FUNCTIONS OF GEOTEXTILESThe Mode of Operation of a Geotextile in any application is defined by six discrete functions. Depending on the application the Geotextile performs one or more of these functions simultaneously.

Functions of Geotextiles

Separation Filtration Drainage Reinforcement Sealing Protection

Separation• Separation -

“The introduction of a flexible porous textile placed between dissimilar materials so that the integrity and the functioning of both the materials can remain intact or be improved”

• Ex:-In transportation applications separation refers to the geotextile’s role in preventing the intermixing of two adjacent soils. By separating fine subgrade soil from the aggregates of the base course, the geotextile preserves the drainage and the strength characteristics of the aggregate material. The effect of separation is illustrated in the figure.

Separation

Mechanical Hydraulic Long-term Performance

During installation Impact resistanceElongation at break

Apparent openingsize ( A.O.S.)Thickness

UV resistance

During construction Puncture resistanceElongation at break

Apparent openingsize ( A.O.S.)Thickness

Chemical stabilityUV resistance

After completion of construction

Puncture resistanceTear propagation resistanceElongation at break

Apparent openingsize ( A.O.S.)Thickness

Chemical stabilityResistance to decay

Required properties for a material to be used for separation:

Apparent opening size (AOS) - A geotextile property, which indicates the diameter of the approximate largest particle that would effectively pass through the geotextile.

Filtration• Filtration –

“The equilibrium geotextile-to-soil system that allows for adequate liquid flow with limited soil loss across the plane of the geotextile over a service lifetime compatible with the application under consideration”

• In filtration, fabrics can be either woven or non-woven, to permit the passage of water while retaining soil particles.

• These applications are also suitable for both horizontal and vertical drains. • A common application for the filtration function is the use of a geotextile

in a pavement edge drain.

Filtration

Mechanical Filter Stability

Hydraulic Filter Stability Long-term Performance

Permanent Filter Function

A.O.S.Thickness

Geotextile permeability Chemical properties of water and soil Chemical stability Decay resistance

Temporary Filter Function

A.O.S.Thickness

Geotextile permeability

Required properties for a material to be used for Filtration:

Drainage (Transmissivity)• The function of drainage is to

gather water, which is not required functionally by the structure, such as rainwater or surplus water in the soil, and discharge it.

• This is distinctly different from the filtration function which involves flow across the plane of the geotextile

• This refers to the ability of thick nonwoven geotextile whose three-dimensional structure provides an avenue for flow of water through the plane of the geotextile.

Drainage (Transmissivity)

Mechanical Hydraulic Long-term Performance

Permanent drainage function

Influence of normal overburden pressure

PermeabilityThicknessApparent opening size (A.O.S.)

Chemical stabilityDecay resistanceChemical properties of water and soil

Temporary drainage function

Influence of normal overburden pressure

Permeability ThicknessApparent opening size (A.O.S.)

Required properties for a material to be used for Drainage:

Reinforcement• This is the synergistic improvement in the total system strength created by the

introduction of a geotextile into a soil.• In the reinforcement function, the geotextile is subjected to a sustained tensile

force or load. Soil and rock materials are noted for their ability to withstand compressive forces and their relative low capacity for sustained tensile forces. In much the same way that tensile forces are taken up by steel in a reinforced concrete beam, the geotextile supports tensile forces that cannot be carried by the soil in a soil-geotextile system.

• Ex :- Reinforcement provided by geotextiles allow embankments and roads to be built over very weak soils and allows for steeper embankments (a wall or bank built to prevent flooding) to be built.

Reinforcement

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

Creep of the geotextile/ soil systemChemical and decay resistance

Required properties for a material to be used for Reinforcement:

Sealing Function• Acting as a barrier for liquid or vapour can be expressed as Sealing.• This function also can be used as buffers against pollutants.• A non-woven geotextile performs this function when impregnated with

asphalt or other polymeric mixes rendering it relatively impermeable to both cross-plane and in-plane flow.

• Ex:-The classic application of a geotextile as a liquid barrier is paved road rehabilitation. Here the non-woven geotextile is placed on the existing pavement surface following the application of an asphalt tack coat. The geotextile absorbs asphalt to become a waterproofing membrane minimizing vertical flow of water into the pavement structure

Protection• Soil protection from natural and seasonal degradation caused by rain,

water, monsoon, wind and cold weather can be considered as the protection function carried out by Geotextiles.

• Ex:-In coastal areas and river valleys erosion of earth embankments by wave action, currents and repeated drawdown is a constant problem requiring the use of non-erodable protection in the form of rock beaching or mattress structures. Beneath these is placed a layer of geotextile to prevent leaching of fine material. The geotextile can be easily placed, even under water.

Protection

Mechanical Long-term performance

Tunnel construction Burst pressure resistancePuncture resistanceAbrasion resistance

Chemically stable: pH=2-13Decay resistance

Landfill and reservoir geomembrane construction

Puncture resistanceBurst pressure resistanceFriction coefficient

Chemically stable: pH=2-13Decay resistance

Required properties for a material to be used for Protection:

Application areas of Geotextiles

Application areas of GeotextilesApplication Separation Filtration Reinforcement Drainage Protection

Temporary and permanent pavements

1 2 2

Asphalt overlays 1 2 2

Railways 1 3 3Embankment 3 3 1 3Retaining walls and slopes 3 3 1 3

Erosion control 3 2 3 3 2Subsurface drainage 3 1

Membrane protection 3 1

(1) Primary Function (2) Secondary Function (3) Tertiary Function

Application areas of Geotextiles

• Civil Engineering Applications– Road Works

• Roadway Separation: Woven or Non Woven• Roadway Stabilization: Woven or Non Woven

– Railway Works • woven or non-woven fabrics are used to separate the soil from the

sub-soil without impeding the ground water circulation where ground is unstable

– River Canals and Coastal Works• Temporary Erosion Control: Coir• Permanent Erosion Control: Woven or Non Woven• Embankments Over Soft Soil: Woven• Lagoon Closures: Woven

Application areas of Geotextiles

• Civil Engineering Applications cont.– Drainage:

• Landfill Drainage Systems: Non Woven

– Sports field construction:• Caselon playing fields - synthetic grass surfaces constructed of light

resistance polypropylene material with porous or nonporous carboxylate latex backing pile

• Astro Turf - a synthetic turf sport surface made of nylon 6,6 pile fiber knitted into a backing of polyester yarn which provides high strength and dimensional stability. Modern Astro Turf contains polypropylene as the base material.

– Agriculture• Mud Control: Non woven

Application areas of Geotextiles

• Some Other Applications of Geotextiles:– Gas Venting: Non Woven – Landfill Leachate(Drain away due water flow)

Collection: Woven or Non Woven– Waste Containment– Steepened Slopes: Woven– Retaining Walls: Woven– Building demolition: geotextile fabrics in combination

with steel wire fencing can contain explosive debris

References• http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.88.4

977&rep=rep1&type=pdf• http://www.bvmengineering.ac.in/docs/published%20papers/ci

vilstruct/struct/101052.pdf• http://www.na.fs.fed.us/spfo/pubs/stewardship/accessroads/ge

otextiles.htm• http://www.engr.utk.edu/mse/Textiles/Geotextiles.htm• http://www.slideshare.net/mukulchandel/mukul-chandel-geotex

tile-2-15702726?from_search=6• http://en.wikipedia.org/wiki/Geotextile• http://en.wikipedia.org/wiki/Geosynthetic• http://www.indiantextilejournal.com/articles/FAdetails.asp?id=4

192• http://www.maine.gov/dep/land/erosion/escbmps/escsectiond1

.pdf• http://www.erosionpollution.com/geotextile-fabric-application.h

tml• http://www.cscos.com/wp-content/uploads/Civil-4_Geotextile-E

ngineering_Bhatia.pdf• http://www.plastemart.com/Plastic-Technical-Article.asp?Literat

ureID=1931&Paper=geotextiles-market-us$6.3-billion-2017-demand-from-emerging-asian-economies

THANK YOU…