Geosynthetics - Geotechnical Investigation and Design Tables - page 203

Geosynthetics

16.1 Type of geosynthetics
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The type of geosynthetics to be used depends on the application.

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The terms geosynthetics and geotextiles are sometimes used interchangeably
although geosynthetics is the generic term and geotextile is a type of product.

Table 16.1 Geosynthetic application.

Application Typical types Examples

Reinforcement Geogrids, Geotextiles Stabilization of steep slopes and walls •

Foundation of low bearing capacity •

Filter Non woven geotextiles,

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Filters beneath revetments and drainage blankets

Geocomposites Separation layer beneath embankment •

Drainage Geonets, Geocomposites

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Erosion control on slope faces

Drainage layer behind retaining walls

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Screen Geomembranes, Geosynthetic Reservoir containment

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clay liner (GCL) Landfills •

- Geogrids are usually biaxial and uniaxial types. The latter usually has a higher
strength, but in one direction only.
- Geonets differ from geogrids in terms of its function, and are generally
diamond shaped as compared to geogrids, which are planar.
- Geocomposites combine one or more geosynthetic product to produce a
laminated or composite product. GCL is a type of geocomposite.
- Geomembrane is a continuous membrane of low permeability, and used as a
fluid/barrier liner. It has a typical permeability of 10 − 13 to 10 − 15 m/s.

16.2 Geosynthetic properties
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The main Polymers used in the manufacture of geosynthetics shown below.

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The basic elements are carbon, hydrogen and sometimes nitrogen and chlorine
(PVC). They are produced from coal and oil.

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PP is the main material used in geotextile manufacture due to its low cost.

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PP is therefore cost effective for non critical structures and has good chemical and
pH resistance.