Engineering Term of the Month – “ Geosynthetics ”
Geosynthetics , in its simplest definition , are man-made materials that are used to improve soil conditions and are most commonly comprised of biologically inert petrochemical-based polymers ( plastics ) that will not decompose from bacteria or fungi . That said , some geosynthetics may be damaged by petrochemicals and many have some degree of susceptibility to ultraviolet light .
The four primary functions of geosynthetic materials are as follows :
- Separate / confine / distribute loads - Reinforce the soil - Prevent movement of soil - Control water pressure 1
Examples of some commonly-accepted types of geosynthetics :
- Geotextiles o Permeable fabrics that are able to separate , filter , protect , reinforce , or drain when used in conjunction with soils . - Geogrids o Support retaining walls , subbases , or subsoils below roads / structures , or to reinforce soil and other similar materials . Greater strength than more common geosynthetics .
- Geonets o Similar to geogrids , these consist of connected sets of “ ribs ” overlying similar sets at various different angles to provide in-plane drainage of liquids or gasses . - Geomembranes o Low-permeability synthetic membrane liner used to control fluid or gas migration in a project , structure , or system , unlike other geosynthetic options that are porous .
- Geosynthetic clay liners o A composite of geotextiles and bentonite , these offer long-lasting resistance to physical / chemical breakdown and are great for containment . - Geocells o Also known as “ cellular confinement systems ”, these cavity-like materials are designed to contain soil and other fill material within their “ pockets ” and are widely used for erosion control , soil stabilization , and structural reinforcement .
- Geofoam o Primary function is to provide a lightweight void fill below highways , bridge approaches , and embankments . Broader applications include thermal insulation , drainage improvement , utility protection , etc .
- Geocomposites o Used to accelerate drainage behind retaining walls , reinforced earth slopes , and other water-bearing structures . 2
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