Geotextiles are permeable textiles used in civil engineering applications to improve the performance of soils. They are made from natural fibers like jute or synthetic polymers like polypropylene and polyester. Geotextiles serve functions like separation, reinforcement, drainage, and filtration. They are used in applications such as roads, erosion control, retaining walls, and drainage systems. The properties and performance of geotextiles depend on factors like material composition, mechanical strength, permeability, and resistance to degradation. Polypropylene is commonly used due to its chemical resistance while polyester has better strength and creep resistance for demanding applications. The suitable fiber depends on the specific geotextile application and requirements.

1. Textiles in Civil
Engineering (Geotextile)
Granch Berhe
2015 1

2. Definition
The word ‘Geotextiles’ is a combination of two words. The word
‘Geo’ comes from the Greek word, meaning ‘Earth’, and textiles
“permeable textiles used in
conjunction with soil,
foundation, rock, earth or any
geotechnical engineering-
related material”
“Any permeable textile material used for filtration, drainage, separation,
reinforcement and stabilisation purposes as an integral part of civil
engineering structures of earth, rock or other constructional materials” 2

3. History
Geotextiles can be made from either natural or synthetic fibres
The exploitation of the use of natural fibres in construction can be traced back to the
fifth and fourth millennia BC as described in the Bible (Exodus chapter 5, verse 6–9)
Babylonians 3000 years ago constructed this
Ziggurat using reeds in the form of woven mats
and plaited ropes as reinforcements
The Great Wall of China, completed circa
200 BC, utilised tamarisk branches to
reinforce mixtures of clay and gravel 3

4. Any permeable textile natural or synthetic, used with foundation
soil, rock, earth, or any other geotechnical engineering related
material.
What is a Geotextile?
Geosynthetics are manufactured (not naturally occurring) materials
that are used to withstand and/or enhance the forces of the in-place
earth.
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5. Method of production Process Form of fibre Polymer
PP/PE bi-component
Continuous filament PP
Heat-bonded
Staple fibre
PP
PP/PE mix
Nonwovens
PP
PET
Staple fibre HDPE
Needle-punched
Continuous filament PP
PET
Nonwoven Geotextiles
Needle Punched nonwoven Thermally bonded nonwoven
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6. Non woven
• More than 75% of the market utilises
geotextiles made from various nonwoven
fabrics, chiefly staple-fibre needlepunched
and continuous-filament spunbonded
nonwovens.
• Nonwoven materials are normally 25–30%
cheaper than woven materials
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7. Method of production Process Form of fibre Polymer
Slit-flat tape PP (HDPE)
Wide loom (beam) Fibrillated yarn PP
Wide loom (creel) Multi-filament yarn PET (PA)
Woven
<3.8m loom (beam)
Medium mono filament
with yarn
PP
HDPE
PA
Woven Geotextiles
film tape extruded tape PET multifilamentMonofil
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8. Woven
• They have a surprisingly wide range of applications and
they are used in lighter weight form as soil separators,
filters and erosion control textiles.
• In heavy weights, they are used for soil reinforcement
in steep embankments and vertical soil walls; the
heavier weight products also tend to be used for the
support of embankments built over soft soils
• Advantage - stress can be absorbed by the warp and
weft yarns and hence by fibres, without much
mechanical elongation
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9. Method of production Process Form of fibre Polymer
Stitched-bonded
Nonwoven base with multi-
filament stitch yarn
PP or PET nonwoven
PET stitching
Knitted Weft insertion filament yarn PET
Warp knitted Multi-filament yarn PET
Knitted Geotextiles
Knitted base Upper surface 9

10. The mode of operation of a geotextile in any application can
be defined by the following functions:
Functions of Geotextile :Functions of Geotextile :
Separator Reinforcement Drainage
Filter Energy absorberContainer

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12. Functions of geotextiles
Filtration – liching of water Drainage - collects and
redirects liquid or gas
Separation – layer between fine
soil and coarse material
Reinforcement - when the stability
of the weak subgrade or soil is
complemented by higher tensile
strength of fabric.
Container - when it holds or protects the
materials such as sand, rocks, fresh concrete12

13. Applications
1. River bank protection.
2. Seabed protection.
3. Sea coastal protection.
4. Coastal protection/sea defences.
5. Drainage.
6. Perpendicular versus in-plane water
flow applications.
7. Reservoirs and lakes.
8. Concrete mattresses.
9. Vertical screens.
10. Geobags.
11. Reclaimed land.
12. Anchoring.
13. Paved and unpaved road subgrade
separation.
14. Embankments.
15. Reinforced earth.
16. Reflective cracking.
17. Railways.
18. Landfills.
19. Slit fences.
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Applications of Geotextile :Applications of Geotextile :
Reservoirs, damsReservoirs, dams
Liquid wasteLiquid waste Solid wasteSolid waste
RoadsRoads RailroadsRailroads
Erosion protectionErosion protection
Retaining wallsRetaining walls
Drainage systemsDrainage systems

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16. 1. Physical properties:
a) specific gravity
b) weight
c) thickness
d) stiffness
e) density .
2. Mechanical properties:
a) tenacity
b) tensile strength
c) bursting strength
d) drapability
e) compatibility
f) flexibility
g) tearing strength
h) frictional resistance
3. Hydraulic properties:
a) porosity
b) permeability
c) permittivity
d) transitivity
e) turbidity /soil retention
f) filtration length etc.
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4. Degradation properties:
a) biodegradation
b) hydrolytic degradation
c) photo degradation
d) chemical degradation
e) mechanical degradation
f) other degradation occurring due to
attack of
rodent, termite etc.
5. Endurance properties:
a) elongation
b) abrasion resistance
c) clogging length and flow etc.
Performance Requirements of Geotextile

17. Properties
• mechanical responses,
– ability of a textile to perform work in a stressed environment and its ability to
resist damage in an arduous environment
– The ability to perform work is fundamentally governed by the stiffness of the
textile in tension and its ability to resist creep failure under any given load
condition
• filtration ability
– function is to hold intact a freshly prepared soil surface, so that water may
exude from the soil surface and through the textile without breaking down that
surface
• chemical resistance
– use of textiles in contact with highly acidic peat soils, where in tropical
countries, pH values down to 2 have been encountered
– Industrialised countries
– Ultraviolet light
They are all developed from the combination of the physical form of the
polymer fibres, their textile construction and the polymer chemical
characteristics
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18. Fibers used
Natural fibres offer high strength, high modulus, low breaking extension and low elasticity.
Some of the plant fibres that
can be used in geotextile
manufacture are jute, sisal,
flax, hemp, abaca, ramie and
coir
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19. Advantages of natural fibers
• low cost,
• robustness,
• strength/durability,
• availability,
• good drapeability
• biodegradability/
environment friendly
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21. Synthetic
• Synthetic fibres are the main raw materials for
the manufacture of all types of geotextiles
– polypropylene, polyester, polyamide and
polyethylene
• polyester widely used
– exhibits superior creep resistance and tenacity values
– is almost inevitably used when high strengths are
required
– applications where the geotextile is subjected to high
stresses and elevated temperatures
– susceptibility to hydrolytic degradation in soils
exceeding pH 10.
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22. • PP
– low cost, acceptable tensile properties and
chemical inertness
– disadvantages of polypropylene are its sensitivity
to ultraviolet (UV) radiation and high temperature
and poor creep and mineral oil resistance
• PA
– cost and overall performance render it inferior to
polyester.
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23. Limitations of synthetic
• Synthetic geotextiles can cost over 10 times as
much per unit area as natural ones
• non-biodegradable and may cause soil
pollution
• The material composition of geotextiles
determines their longevity in the field: natural
products last about two to five years, whereas
synthetic products last >25 years
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24. • Erosion control geotextiles are made from
natural (jute, coir, sisal, cereal straw and palm
leaves) or synthetic (nylon, polypropylene,
polyester and polyethylene) materials
• Geotextiles are used for separation of two
distinct ground layers, slope stabilization,
vegetation management and soil erosion control.
• Geotextiles are widely used to control on-site and
off-site soil erosion of human-disturbed lands
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25. PET Vs PP in Geotextile Applications
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Property PET PP
g/cm3 1.38 0.91- 0.93
Melting Point 265 165
Strain 10 -15 > 100 %
Creep < 2% 5%
Modulus (Gpa) 10 2.8
Breaking Elongation 20-50 % 40 -70 %
Breaking Tenacity
(gm/d)
9 6
UV Resistant High Susceptible
Polar solvents Degrade Resistant
pH > 9.5
Hydrolysis
3 -13
Moisture Regain 0.4 0

26. Polypropylene Polymer has distinct advantages
1. Resistant to chemical attack
2. Stable to pH between 3 and 13
3. Non-biodegradable
4. Resistant to soil-bound chemicals, landfill leaches, mildew and
insects.
5. Lightest fibre
Polyethylene Terephthalate (PET) Polymer has :
1. Superior Breaking Tenacity (Strength)
2. Superior creep characteristics required in some critical
reinforcement materials.
 PET must not be used in contact with soils with pH >9.5
 For PET made Geotextiles hydrolytic resistance is required to be
observed.
 For Geotextile application in case of PP Oxidative resistance is required
to be observed.

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Temperature resistance
PET is winning with a melting point of 265o
C versus the 165o
C of PP. This means that
for applications which need temperature resistance e.g. resistance to reflective
cracking in roads, PET is preferable.
Creep
PET by far the best choice.
Chemical resistance
Generally PP is better. PP is preferred for landfills.
Alkali resistance
Again PP is the better choice e.g. in touch with fresh concrete.
UV resistance
This is a PET domain. PP geotextiles should be improved with carbon black for a
better behavior to UV.

28. Technical Requirement for use in subsurface drains
• Breaking load not less than 10 kN/m
• Minimum Failure strain of 10%
• Apparent opening size 0.22mm – 0.43 as soil properties
• Allow water flow @ not less than 10lit/sqm/sec
• Minimum puncture resistance of 200 N
• Minimum tear resistance of 150N
PET is Preferable Than PP
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29. Technical Requirement for use in Highway Pavement
• Minimum Tensile strength 36.3 Kg
• Elongation 50%
• Asphalt Retention 10 kg/10sqm
• Melting Point 150C
• Surface Texture- heat Bonded on one side only
PP is Preferable Than PET
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30. Technical Requirement for use in Protection Works
• Aperture : Rectangular, square or oval
• Colour : Black
• Strength : Min 10kN/m
• Elongation: Max 15%
• Life : Min 8 years
PET is Preferable Than PP
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Silt Fence• Prevents storm water from
transporting sediment off-
site
• Alternate for hay bales
• Low elongation (stretch)
important for more support
• Filtration and tensile
strength properties most
important
• Commonly light weight
woven (higher strength)
geotextiles
PET is Preferable Than PP

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Roadway Separation / Stabilization
• Prevents subgrade from
intermixing with base
course
• Alternate to
undercutting
• Low elongation for
higher modulus
PET is Preferable Than PP

33. PP is Preferable Than PET if pH is >9.5 33

34. PET is Preferable Than PP
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35. 35
Geotextiles in Drainage
Geotextile
around pipe
Geotextile
around pipe
Geotextile
lining trench
Lining pipes not preferred method
PP is Preferable Than PET

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Filtration
w/ geotextile
w/o geotextile -
loss of fines
PP is Preferable Than PET

37. Avoid granular material penetration
Puncture resistance
PP is Preferable Than PET
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Thank You!

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