A geotextile is defined as any permeable textile material that is used with foundation, soil, rock, earth, etc to increase stability and decrease wind and water erosion.

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2. INTRODUCTION
 Geotextiles are permeable fabrics which, when used in association
with soil, have the ability to separate, filter, reinforce, protect, or drain.
 Typically made from polypropylene or polyester, geotextile fabrics
come in three basic forms:
• woven (looks like mail bag sacking)
• needle punched (looks like felt)
• heat bonded (looks like ironed felt).

4. FUNCTIONS OF GEOTEXTILES
 Filtration
 Drainage
 Separation
 Reinforcement
 Sealing

6. FILTRATION
The equilibrium geotextile to soil
system that allows for adequate
liquid flow with limited soil loss
across the plane of geotextile over
a service lifetime.

7. DRAINAGE/TRANSMISSIVITY
Ability of thick nonwoven geotextile
whose 3-dimensional structure
provides an avenue for flow of water
through the plane of the geotextile.

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

9. REINFORCEMENT
Geotextile acts as a reinforcing element in
a soil mass or in combination with the soil
to produce a composite that has improved
strength and deformation properties.

10. SEALING
• The classic application of a geoxtile
as a liquid barrier is paved road
rehabilitation.
• It minimizes vertical flow of water
into the pavement structure.

11. TYPES OF GEOTEXTILES
Woven fabrics
Non-woven fabrics
Knitted fabrics

12. DESIGN PROPERTIES
 Puncture Strength
 Burst Strength
 Dynamic Puncture
 Permeability
 Apparent Opening Size (AOS)
 Grab Tensile Strength and Elongation

13. PUNCTURE STRENGTH
 To measure puncture resistance
 Stimulates puncture strength to static load of aggregates
 Resistance to puncture measured in Newton

14.  Stimulates strength of geotextile to a continuous hydraulic load
 Force causing rupture recorded in units of pounds per square inch or kilo
Pascal.
BURST STRENGTH

15. DYNAMIC PUNCTURE
 To measure the strength of geotextile to falling objects.
 Stimulates placement of aggregate over geotextile during installation
stage.
 Expressed in mm.

16. PERMEABILITY
 Measures the rate at which liquids can pass through the geotextile
 x=k/t
x- geotextile permittivity (sec-1)
k- geotextile permeability(cm/sec)
t- geotextile thickness (mm)
 Expressed in liters per square meters per second

17. APPARENT OPENING SIZE (AOS)
 Reflects approximate largest opening dimension available through which
the soil may pass.
 Expressed in mm.

18. GRAB TENSILE STRENGTH AND
ELONGATION
 Measures tensile strength and elongation along the plane of the
geotextile by loading it continually
 Value of breaking load expressed in Newton and elongation at break in
percent.

19. AREAS OF APPLICATION
• Flexible paved road construction
• Drainage applications
• Pavement overlays

20. FLEXIBLE PAVED ROAD CONSTRUCTION
Function of geotextiles:
• service life of roads
• load carrying capacity
• rutting

21. RESEARCHES ON GEOTEXTILE
For weak subgrades (CBR=2%)
 Service life by a factor of 2.5-3.0
 AASHTO structural number by 19%
For moderate strength (CBR=4.2-4.5%)
 Service life by a factor of 2.0-3.3
 AASHTO structural number by 13-22%

22. AASHTO DESIGN METHOD
Excellent drainage
 SNeff
 Drainage factor - 1.20
Poor drainage
 SNeff
 Drainage factor as 0.60

23. GEOTEXTILE REQUIREMENT
Selection of geotextile
 Depends on survivability
 Governed by anticipated construction stresses

25. PAVEMENT OVERLAYS
Benefits of using Fabric Interlayer
 Waterproofing of the lower layers
 Retarding reflection cracking in the overlay
 Increase in structural stability
 Absorption of stresses

27. CAPABILITIES OF PAVING FABRICS:-
 Reduces permeability of a pavement
 Reduces infiltration of moisture
 Maintains the strength of subgrade, sub base and base course
 Limiting damage due to saturated condition pore pressures

28. PROPERTIES OF PAVING FABRICS
 Nonwoven fabrics from grades ranging from 135gm/m² to
200gm/m²
 Lighter fabrics are moisture barriers
 Heavier fabrics provides cushioning or stress-relieving
membrane

29. INSTALLATION PROCEDURE
• The surface is cleaned
• Cracks are filled or repaired
• Tack coat ranging from 1-1.35 l/m² of residual asphalt is evenly
applied
• The paving fabric is laid with minimum wrinkles
• Finally hot mix overlay is placed

31. DRAINAGE
• Drainage system should fulfill 2 criteria:-
• Have maintained permeability
 by providing relatively unimpeded flow of water
• Filtration of base soil
 by preventing the migration of soil fines into the drain

33. CONCLUSION
 Geotextiles are an efficient effective and economic method of solving
most of the geotechnical problems in roads.
 The design engineer should be well aware of the possible problems
and should use this relatively new tool for solving them.
 For this he/she should understand properties and capabilities of the
geotextile material.

34. THANK YOU
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