Civil and Environmental Applications of Geosynthetics - Reinforced Soil Engineering: Advances in Research and Practice - page 2

the standards relevant to their applications. The American Society for Testing and
Materials (ASTM) is one developer of standardized testing procedures for
different geosynthetics. Most testing standards adopted or developed in other
countries are outgrowths of ASTM standards. The Geosynthetic Research
Institute (GRI) also provides testing standards to serve industrial needs,
especially when related ASTM standards have not been developed. GRI
standards are usually removed as related ASTM standards become available.
ASTM standards, developed under Committee D35 for Geosynthetics, are
listed in the Appendix. These standards were developed under several
subcommittees: terminology, mechanical properties, endurance properties,
permeability and filtration, geosynthetic clay liners, geosynthetic erosion
control, and geomembranes. New standards are constantly being developed.
Details of test standards are published in ASTM (2000).
While ASTM standards are index tests, many civil engineering designs and
applications require the geosynthetic materials to be tested with site-specific
soils, with the testing conditions representing those in the field. These kinds of
tests are known as performance tests.

2.2 Design by Function

Different organizations, agencies, and manufacturers provide design guidelines
for geosynthetic applications. These design methods are determined by cost,
specification (design by specification), or function (design by function). Public
agencies have widely adopted the design-by-specification method. The minimum
required value of the geosynthetic properties used in a particular application is
specified.
In the design-by-function method, the primary function of the geosynthetic
material is identified. The available and required value of the particular property
for that function is assessed to give a factor of safety (FS):

allowable property from testing
required property for design

¼

FS

Designs require a factor of safety greater than unity to account for various
uncertainties.

3 GEOTEXTILES, GEOGRIDS, AND
GEONETS/GEOCOMPOSITES

Geotextiles are the earliest type of multifunctional geosynthetic material. Their
functions include reinforcement, separation, filtration, and drainage. When