Geosynthetics are widely used in many geotechnical, environmental, and hydraulic applications related to groundwater quality and control.

1. MODULE 4.
Earth Reinforcement-Reinforcement materials-reinforced earth wall-design
considerations construction procedure
Soil nailing & Micro pile-basic concept-construction sequence-areas of
application-design considerations-merit and demerit
Geosynthetics - use, type-function- filtration, drainage, separation-Application of
geotextile in different works

2. GEOSYNTHETICS

3. the term used to describe a range of generally polymeric products
used to solve civil engineering problems
available in a wide range of forms and materials, each to suit a
slightly different use
generally regarded to encompass eight main product categories:
geotextiles, geogrids, geonets, geomembranes, geosynthetic clay
liners, geofoam, geocells, geopipes and geocomposites

4. • Geosynthetics can be defined as planar products manufactured from polymeric
material, which are used with soil, rock, or other geotechnical engineering related
material as an integral part of a manmade project, structure, or system.
• Geosynthetics are widely used in many geotechnical, environmental, and hydraulic
applications related to groundwater quality and control.
• One of the most common examples is the use of geotextile filters in trench (i.e.,
French) drains.
• Base and cover liner systems for modern landfills also make extensive use of
geosynthetics with the main purpose of minimizing the potential for groundwater
contamination.

5. Advantages
• Space Savings
• Material Quality Control
• Construction Quality Control
• Cost Savings
• Technical Superiority
• Construction Timing
• Material Deployment
• Material Availability
• Environmental Sensitivity

6. Disdvantages
• Clogging of geotextiles, geonets, geopipe and/or geocomposites
is a challenging design for certain soil types or unusual situations
• Handling, storage, and installation must be assured by careful quality
control and quality assurance
• Long-term performance of the particular formulated resin being used
to make the geosynthetic must be assured by using proper additives

7. Materials used for Geosynthetics:
• Polyamide
• Polyester
• Polyethylene-LDPE,LLDPE,HDPE
• Polypropylene • Poly vinyl chloride
• Ethylene copolymer bitumen
• Chlorinated polyethylene

8. Properties of Geosynthetics
• Material & fibre properties - temperature & water content
• Geometrical aspects - field boundary conditions, method of
execution, width & length, thickness, mass per unit area.
• Mechanical properties - interface friction, fatigue resistance, creep
resistance, tear strength, abrasion resistance, seam strength and
other.
• Hydraulic properties - filtration & drainage requirements.
• Durability or chemical properties - abrasion resistance & UV
resistance.

9. Geotextiles
Permeable fabrics made from polypropylene or polyester
Consists of synthetic fibres made into a flexible, porous fabric by
standard weaving machinery or are matted together in a random, or
nonwoven, manner.
Polypropylene – lighter then water, strong & durable
Polyester – heavier than water, excellent strength & creep properties
Geotextiles – woven and nonwoven

10. Woven Geotextiles
By weaving together narrow strips of film
In the form of extruded tape, slit fi
• Weaving – process of interlacing yarns to make a fabric
• Two steps
• Manufacture of the filaments or slitting the film to create yarns
Weaving the yarns to form the geotextile
Sediment control and road stabilization applications

11. Non-woven Geotextiles
• By entangling plastic fibres or bonding them chemically or
with heat
• Either from short stable fibres or continuous filament yarns
• Continuous filaments randomly distributed in layers onto a
moving belt to form a web and then passes through a bonding
machine interlocking the filaments.
• Subsurface drainage, erosion control applications, road
stabilization

14. Geogrids
• Single or multilayer materials usually made from extruding or
stretching high-density polyethylene or polypropylene or by weaving
or knitting and coating high tenacity polyster yarns.
• Resulting grid structure possess large openings which enhance soil
aggregate interaction.
• Effective in soil & aggregate reinforcement

16. Geonets
• Made of stacked or criss-crossing polymer strands thet provide in-
plane drainage
• Generally of Polythene
• Molten polymer is extruded through slits in counter rotating dies
forming a net of closely spaced strands

18. Geocomposites
• Combination of different geosynthetics
Drainage geocomposites
Composed of a geotextile filter surrounding either a geonet or any
drain
Applications are blanket drain, panel drains, edge drains and wick
drains

20. Geomembranes
• Relatively impermeable sheets of plastic
• Two types – calendered and extruded
• Calendered – by flattening a molten formulation between counter
rotating rollers. PVC, Chlorosulphonated polythene(CSPE),
polypropylene(PP)
• Extruded – by melting polymer resin and forcing it using a die through
a screw extruder to form a flat wide sheet advanced on a conveyor belt
or cylindrical tube

22. Geosynthetic Clay Liners (GCL’s)
• Include a thin layer of finely-ground bentonite clay
• When wetted, the clay swells and becomes a very
effective hydraulic barrier
• Manufactured by sandwiching the bentonite within or
layering it on geotextiles or geomembranes, bonding the
layers.

24. Geopipe
• A geosynthetic plastic pipe using specific polymer
resins
• HDPE,PVC, PP (polypropylene), PB (polybutylene),
ABS (acrylonitrile butadiene styrene), and CAB
(cellulose acetate butyrate)
• Highway and railway edge drains, interceptor drains,
leachate removal systems

26. Geofoam
• Large blocks which are stacked to form a light-weight, thermally
insulating mass buried within soil or pavement.
• Most commonly used from polystyrene
• Within soil embankments built over soft soils, under roads, airfield
pavements, railway track systems and beneath on-grade storage tanks
containing cold liquids.

28. Applications
• Separation
• Reinforcement
• Filtration
• Drainage
• Containment
• Protection

30. Functions of Geosynthetics
1. Separation
• The geosynthetic, placed between two dissimilar materials, maintains
the integrity and functionality of the two materials.
• It may also involve providing long term stress relief.
• Key design properties to perform this function include those used to
characterize the survivability of the geosynthetic during installation

32. 2. Filtration:
• The geosynthetic allows liquid flow across its plane, while
retaining fine particles on its upstream side.
• Key design properties to fulfil this function include the
geosynthetic permittivity (cross-plane hydraulic conductivity per
unit thickness) and measures of the geosynthetic pore-size
distribution (e.g. apparent opening size)

34. 3. Reinforcement:
• The geosynthetic develops tensile forces intended to maintain or
improve the stability of the soil geosynthetic composite.
• A key design property to carry out this function is the geosynthetic
tensile strength and those used to quantify the stiffness of the soil-
geosynthetic composite.

36. 5. Drainage:
• The geosynthetic allows liquid (or gas) flow within the plane of its structure.
• A key design property to quantify this function is the geosynthetic transmissivity
(in-plane hydraulic conductivity integrated over thickness).
6. Hydraulic/Gas Barrier:
• The geosynthetic minimizes the cross-plane flow, providing containment of liquids
or gases.
• Key design properties to fulfil this function include those used to characterize the
long-term durability of the geosynthetic material.

38. 7. Protection:
• The geosynthetic provides a cushion above or below other material (e.g. a
geomembrane) in order to minimize damage during placement of overlying
materials.
• Key design properties to quantify this function include those used to characterize
the puncture resistance of the geosynthetic material.