This document discusses different types of geo-synthetics, which are man-made materials used in geotechnical engineering and construction. It describes eight main categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geocells, geofoam, and geocomposites. Geotextiles are the most commonly used and can be woven or non-woven. Each geo-synthetic has different characteristics and functions, such as separation, reinforcement, filtration, drainage, or containment. Tests are conducted to evaluate geo-synthetics' properties. The conclusion discusses the growth of these materials and their promising future applications.
2. What is geo-synthetic?
A geo-synthetic has been defined by the “American Society for Testing and
Materials (ASTM) Committee D35 on Geo-synthetics” as “A planar product
manufactured from polymeric material used with soil, rock,
earth, or other geotechnical engineering related material as an
integral part of a man-made project, structure, or system.”
3. Geo synthetics are classified as follows:
1. Geotextiles
2. Geogrids
3. Geonets
4. Geomembranes
5. Geosynthetic clay liners
6. Geocells/geo web members
7. Geofoam
8. Geocomposites
4. Geotextiles
Geotextiles are defined as “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.
Composed of polymers like polypropylene, high density polyethylene, polyster.
Function: Separation, Reinforcement, Filtration, Drainage.
5.
6. 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
•Have high tensile strength and relatively low strain.
7. 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.
8. 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
9. GEONETS
(Geospacers)
•Formed by continuous extrusion of
parallel sets of polymeric ribs(LDPE &
HDPE) at preset angles to one another.
•Their 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 .
10. GEOMEMBRANES
•Materials are relatively thin impervious
sheets .
•Generally made from butyl rubber.
•The sell of geomembrane are greater than
geotextiles.
11. GEOSYNTHETIC CLAY LINERS
•This is the juxta position of polymeric
materials and natural soil.
•Factroy fabricated and betonite clay is
sandwitched between 2 geotextile.
•Structural integrety is obtained by needle
punching.
•Function: Containment,As Hydraulic
barrier.
12. 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.
•Allow water through it.
•USE: In slopes with soft sub-grade
erosion control in channels
13. GEO FOAM:
•Large but but extreamly 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,
14. 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 Composiets
Geotextile –Geogrid Composiets
Geomembrane –Geogrid Composite
Geotextile-Polymer Core Composite
15. 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
FUNCTION OF GEOSYNTHETIC MATERIALS:
A Comparative Review.
16. TESTS ON GEOSYNTHETICS:
1. Grab test
2. Seam testing
3. Puncture test
4. CBR push through test
5. Tear test
6. Diaphragm bursting strength test
7. Cone drop test
8. Dry sieve test
9. Gradient test
17. CONCLUSION
The rapid growth in the geosynthetic market the world
over has lent confidence to the civil engineer in their use.
One should not be tempted to imagine geosynthetics are
magical materials to yield excellent results, without due
consideration of the problem or soil geosynthetic
interaction. Such a blind approach could lead to disaster.
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.