Geo-synthetics are synthetic polymer products used in construction to provide separation, drainage, filtration, reinforcement and containment functions. They include planar structures like geotextiles, geomembranes and geogrids as well as three-dimensional structures like geocells. Common geo-synthetic materials are polypropylene, HDPE, polyester and PVC. They are widely used in roads, drainage works, erosion control, retaining walls and reinforced soil structures to provide long-term, cost-effective solutions with environmental benefits like pollution control and resource efficiency.

1. GEO-SYNTHETICS IN THE
CONSTRUCTION WORKS
Prepared by,
S.INDHU

2. What are Geo-synthetics ?
 Geo-synthetics are synthetic products, where at least one of the
components is made from a synthetic or natural polymer, in the
form of a sheet, a strip or a three dimensional structure, non-
woven, knitted, or woven which is used in contact with soil/rock
and/or other materials in geotechnical and civil engineering
applications .
These include:
 Planar structures (Geomembranes, geotextiles, geosynthetic
barriers, Geonets, Geogrids, geostrips, geospacers and geomats,
etc.) and
 Three-dimensional structures (geocells, geofoams, gabions and
concrete filled mattresses).

3. Geo-synthetics composition:
 Polypropylene
 H D P E
 Polyester
 PVC
 Synthetic Rubber
 Natural fibers – Jute, coir

4. Geo-synthetics functions:
 Separation
 Drainage
 Filtration
 Moisture barrier
 Cushion

5. Separation function and Drainage
function:

6. Filtration function and Geo-membrane
Seepage Barrier:

7. Reinforcement function:

8. Geo-synthetics are classified as follows:
 Geotextiles
 Geogrids
 Geonets
 Geomembranes
 Geosynthetic clay liners
 Geocells/geo web members
 Geofoam
 Geocomposites
 Geopipe
 Turf Reinforcement mats

9. 1. Geotextiles:
 Any permeable textile used with foundation soil, rock, earth, or
any other geotechnical engineering-related material as an integral
part of a human-made project, structure, or system.
Characteristics:-
 Porous and allow flow of water through it. Most used
Geosynthetics.
 They may be either woven or non woven. Available in rolls of
5.6m wide and 50-150m long. It Composed of polymers like
polypropylene, high density polyethylene, polyester.
 Function: Separation, Reinforcement, Filtration, Drainage.

10. Woven geotextile:
 Uniform and regular interweaving of threads or yarns in two
directions.
 Regular Visible Construction Pattern.
 Function: Soil Separation, Reinforcement, Load distribution,
Filtration, Drainage. It have high tensile strength and relatively
low strain.

11. Non woven geotextile:
 Formed by heat bonding, resin bonding or needle punching.
 No visible thread pattern.
 Function: Soil separation, stabilization, load distribution, but not
used for reinforcement.
 They have high strain and stretch considerably under load.

12. 2.Geogrids
 They have open grid like configuration i.e. they have large
aperture between individual ribs. They have Low strain and stretch
about 2% under load. Strength is more that other common
geotextiles.
 Function: Used exclusively for reinforcement. It enhances the
interaction between soil and aggregate.

13. 3. Geonets (Geospacers):
 Formed by continuous extrusion of parallel sets of polymeric
ribs(LDPE & HDPE) at preset angles to one another.
 design function is completely within the in-plane drainage area where
they are used to convey all types of liquids.
 Though they are used for the drainage function but they have high
tensile strength.
 Generally used along with one or two geotextile matter one at the top
and other at the bottom to prevent soil intrusion .

14. 4. Geomembranes
 Materials are relatively thin impervious sheets .Generally made
from butyl rubber.
 The sale of Geomembrane are greater than geotextiles.
Impervious thin sheets of rubber or plastic materials primarily
used for the lining and covers of liquid and solid impoundments.

15. 5.Geosynthetic Clay Liners:
 Factory fabricated and bentonite clay is sand witched between 2
geotextile. Structural integrity is obtained by needle punching.
Function: Containment, As Hydraulic barrier. Include thin layers of
finely grounded bentonite clay.
 Clay swells and becomes a very effective hydraulic barrier when
wetted. Manufactured by sandwiching bentonite within/layering it on
geotextile and Geomembranes.

16. General Configuration of Geosynthetic Clay
Liners:

17. 6.Geo Cells/Geo Web Members:
 Similar to geotextiles or Geogrids but have depth. Formed by High
Density Polyethylene sheets.
 When opened form honey comb like structure and that contain soil,
gravel and it allow water through it. Most preferably used in slopes
with soft sub-grade erosion control in channel.

18. 7. Geo Foam:
 Large but extremely light materials with gas filled cells. Made from
expanded poly styrene and extruded poly styrene by polymeric
expansion process.
 Function: separation, lightweight fill, compressible inclusions, thermal
insulation.
 Applications: Used within Soil embankments built over soft weak
soils, used under roads, airfields, railway track systems, which are
subjected to excessive freeze and thaw conditions and used beneath on
grade storage tanks containing cold liquids.

19. 8.Geocomposites:
 This is a factory fabricated unit with two or more geosynthetic
components. This is prepared to extract all the major properties of the
Geosynthetics into a single unit with minimum cost. Along with
geosynthetic materials sometimes some non geosynthetic materials are
also used.
The various types of Geocomposites are :-
 Geotextile-Geonet Composites
 Geotextile –Geomembrane Composites
 Geotextile –Geogrid Composites
 Geomembrane –Geogrid Composite
 Geotextile-Polymer Core Composite

20. 9.Geo pipe:
 It is a plastic pipe prepared by using the resins are High density
polyethylene, Polyvinyl chloride, polypropylene, polybutylene etc., It
include leachate removal systems, interceptor drains, highway and
railway edge drains.

21. 10. Turf Reinforcement Mats:
 Three dimensional structures composed of fused
polymer nettings randomly laid monofilaments or
yarns woven into open and dimensionally stable
mats.it is used to control the erosion.

22. FUNCTION OF GEOSYNTHETIC MATERIALS:
A Comparative Review.
Types Of
Geosynthetics
Separation Reinforcement Filteration Drainage Containment
Geotextile YES YES YES YES
Geogrid YES
Geonet YES
Geomembrane YES
GCL YES
Geofoam YES
Geocomposites YES YES YES YES YES

23. Geo-synthetics areas of Application
 In Roads and Pavements: Subgrade separation and Stabilization, Base
Reinforcement, Overlay Stress Absorption and Reinforcement.
 In Subsurface Drainage: Subgrade dewatering, Road base drainage,
Structure drainage. Hydraulic Works: For the construction of basins,
dams and canals.
 Tunnels: For the tunnels and the underground works.
 In Erosion and Sediment Control: Hard Armor Systems, Silt Fence.
Protect the shorelines, slopes, channels, canals ,landslides, steepened
slopes, surface erosion.
 In Reinforced Soil Systems: Embankments over soft foundations,
Reinforced Steepened slopes, Reinforced soil walls. For Foundations,
supporting works, soft soils works.
 In Seepage control system: structure water proofing, Environmental
Protection.
 In Support Systems: Prefabricated Systems and On-site Fabrication

24. Retaining, RC Walls And Bridge Abutments:

25. Erosion Control:

26. Erosion of unprotected section Failure of geotextile layer
Protection of embankment by geotextile Geotextile for erosion control

27. Economic Importance of Geosynthetics
Commonly accepted as durable, long lasting and
environmentally safe solutions to geotechnical
engineering projects.
The cost of geo-synthetics applied usually between 3
to 5 per cent of the total cost of projects.
For a number of projects, savings of 30 per cent in
total project costs have been reported.
Minimizes the regular repair and maintenance costs
directly.
Prevent accidents, increase efficiency of structures,
minimize pollution and leads to efficient use of natural
resources.

28. Environmental Importance of Geosynthetics:
 The civil engineering structures need to have long term
durability to prevent potential ecological disasters
(floods, draughts, earthquakes, global warming) .
Geosynthetics provide such long lasting solutions with
minimum cost.
 Geo-techs are difficult or impossible to degrade. However,
in view of their inert nature they can be disposed off
without the danger of contamination.
 Geosynthetics assist the environment by acting as a
containing barrier for toxic materials.
 The envisaged functional lifetime of Geosynthetics is
extremely long, in many cases over 100 years.
 Geosynthetics provide sealing and capping of pollution
due to chemicals released after road and rail accidents into
groundwater areas.

29. Conclusion
 The future appears to be more promising with stronger & more
durable Geosynthetics emerging into the market along with
fibrous system to be mixed with soil for giving more hope as well
as challenge to the Geotechnical engineer in the years to come.

30. Thank you