1. GEOTEXTILES IN TRANSPORTATION APPLICATIONS1
GEOTEXTILES IN
TRANSPORTATION
APPLICATIONS

2. INTRODUCTION
Defined as permeable textile materials used in contact with the soil, rock, earth etc as an integral part of civil engineering project, structure, or system

3. FUNCTIONS OF GEOTEXTILES
Filtration
Drainage
Separation
Reinforcement
Sealing

4. 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

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. REINFORCEMENT
Improvement in the total system strength created by the introduction of geotextile into soil
Three mechanisms involved:-

9. 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. Burst Strength
stimulates strength of geotextile to a continuous hydraulic load
force causing rupture recorded in units of pounds per square inch or Kilo Pascal

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 permittivitty (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
AASHTO structural number by 19%
For moderate strength (CBR= %)
Service life by a factor of
AASHTO structural number by 13-22%

22. AASHTO DESIGN METHOD SNeff Drainage factor - 1.20 poor drainage
excellent drainage
SNeff
Drainage factor
poor drainage
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

26. 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

27. 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

28. Installation Procedure
the surface is cleaned
cracks are filled or repaired
tack coat ranging from l/m² of residual asphalt is evenly applied
the paving fabric is laid with minimum wrinkles
finally hot mix overlay is placed

30. Drainage by providing relatively unimpeded flow of water
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

32. 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.

33. THANK YOU