Geosynthetics are polymeric materials used with soil to modify its engineering properties. There are several types of geosynthetics including geotextiles, geogrids, geomembranes, and geocomposites. Geotextiles include non-woven, woven, and knitted fabrics which are made of polymers like polypropylene, polyethylene, and polyester. Geogrids are formed by joining intersecting polymer ribs to create a grid-like structure with large openings. Geomembranes are thin, impermeable polymer sheets used to control fluid movement. Geosynthetics function by providing separation, reinforcement, filtration, drainage, barriers, protection, and stiffening to soils

1. GEOSYSNTHETICS
Dr K M Soni, ADG(Retd.), CPWD,
New Delhi

2. Geosysnthetics
Geosynthetics are the polymeric materials
used with geological materials to modify civil
engineering properties.
Therefore, the definition includes the
following;
• Polymeric materials
• Used with geological materials
• Modification of properties

3. Polymeric Materials
Geosynthetics are made of polymeric
materials like polypropylene, polyester, and
polyethylene.
Now natural synthetic materials or natural
materials are also used to manufacture
geosynthetics like jute, coir and glass fibres.

4. Type of Polymeric Geosynthetics
• Geotextiles
• Geogrids
• Geomembranes
• Geocomposites

5. Geotextiles
• Non woven geotextiles
• Woven geotextiles
• Knitted geotextiles

6. Non Woven Textiles
• Non-woven geotextiles are manufactured
from either continuous filament yarn or short
staple fiber
• The bonding of fibers is done using thermal,
chemical or mechanical techniques or a
combination of these

7. Needle punched Chemically bonded Thermal bonded

8. Woven Geotextiles
• Woven geotextiles are woven type
manufactured using to weaving techniques
like usual clothing textiles.
• The yarn running along the length is called
warp and the perpendicular one is called
weft.

10. Knitted Geotextiles
• Knitted geotextiles are manufactured by the
process of interlocking a series of loops of
yarn together using the knitting technique in
conjunction with some other method.

11. Geogrids
• Geogrids are polymeric products formed by
joining intersecting ribs having large open
spaces i.e. apertures. The directions of the ribs
are referred to as machine direction orientated
in the direction of the manufacturing process or
cross machine direction perpendicular to the
machine direction ribs.
• Geogrids are extruded and then pulled either in
one direction called as mono-oriented geogrids,
or in the two main directions known as bi-
oriented geogrids.

12. Uniaxial geogrid Biaxial geogrid

13. Geomembranes
• Geomembranes are synthetic membranes
made from relatively thin continuous
polymeric sheets of very low permeability
used to control fluid (or gas) migration.

14. Geocomposites
• Geocomposites are combination of various
Geosynthetics materials like Geotextile,
Geogrids and Geo-membranes bounded for
specific applications.

15. Geosynthetics
• Other types of geosynthetics are known as:
• Geonets
• Geosynthetic clay liners
• Geofoams
• Geocells
Geonet Geosynthetic clayliner Geofoam blocks Geocells

16. Principle of working of Geosynthetics
• Friction for reinforcing action
• Hydraulic flow

17. Friction
• Friction between soil and geosynthetics
– Thus soil has to be frictional soil like sand
– Geosynthetics may be of geogrids, geotextiles,
Geofoams
Uses are for roads, retaining walls,
embankments, bearing capacity
improvement

18. Hydraulic flow
• Hydraulic flow required
– filtration across the plane
– drainage along the plane
– Uses of non woven geotextiles, Geodrains
• Hydraulic flow not required
– Geomembranes
– Geotextile clay line

19. Friction and hydraulic properties
• Geonets
• Geocells

20. Functions
• Separation
• Reinforcement
• Filtration
• Drainage
• Barrier
• Protection
• Stiffening

21. Separation
• Mixing of soft and hard materials

22. Reinforcement
• Retaining walls
• Bearing capacity improvement

23. Drainage/Filtration
• Drains
– Non woven geotextiles
• Gabions
– For reinforcing action, Geogrids, for filtration and
drainage: Non woven geotextiles
• Geopipes
– Non woven geotextiles

24. Barriers
• Geocomposites
• Geotextile clay liners

25. Thanks for attending
Dr K M Soni, ADG (Retd.), CPWD, New Delhi
Also available on Youtube: KRISHNA MURARI Soni at
https://www.youtube.com/channel/UC_pPYxk0jI1ayqA5rO6fBOw