General design aspects - Geosystems: Design Rules and Applications - page 15

Table 2.6 Resistance of geotextile raw materials to various environments. Since LDPE is not used
in geotextile-encapsulated sand elements the properties of HDPE are shown here
[22, paragraph 3.1.3].

Raw material Polyester Polypropylene Polyethylene

Exposure duration Short Long Short Long Short Long

Diluted acids

++ + ++ ++ ++ ++

Concentrated acids 0 -

++ + ++ ++

Diluted alkali 0

++ ++ ++ ++ ++

Concentrated alkali 0 -

++ ++ ++ ++

Salt ++ ++ ++ ++ ++ ++

Mineral oil 0 0

++ ++ + +

Glycol 0 ++ ++ ++ ++ ++

Micro-organisms ++ ++ ++ ++ ++ ++

UV-light 0 0 - 0 -

+

UV-light* ++ + ++ + ++ +

Dry heat up to 100 ° C 0

++ ++ ++ + +

Steam up to 110 ° C 0 - 0 - 0 +

Liquid absorption ++ ++ ++ ++ ++ ++

Detergents

++ ++ ++ ++ ++ ++

Short = from manufacture until installation.
Long = during actual lifetime of the works.
*

= resistance after addition of UV stabilisers.

++ = good resistance; + = reasonable resistance; 0 = poor resistance; - = no resistance.

Table 2.7 Allowable tensile strength as percentage of the original
tensile strength due to creep at 20 ° C.

Percentage of maximum tensile strength
due to creep

Material 2 years 10 years 50 years

Polyester 75% 70% 60%

Polypropylene 50% 40% 25%

Polyethylene 50% 40% 25%

placement. Once the element has been placed, the applied tensile loads tend to be
small and thus the effects of creep are negligible.
When using polyester geotextiles one should be aware that during the filling with
sand the filaments of the geotextile may become damaged due to abrasion by the
movement of sand. Other geotextile types are less susceptible to abrasion.
In summary, in selecting the geotextile the following aspects require attention:

￿ duration of the stress during the life of the structure;

￿ manner of construction;

￿ duration of the exposure to UV radiation;

￿ rate of leaching of anti-oxidants and UV stabilisers;