Geotextiles used in civil engineering applications are designed to provide service over the specified design period.
There are various factors that influence the design life of a geotextile. These include the physical environment, the chemical environment, the installation method and the storage conditions. It is imperative that the chosen geotextiles are able to provide service of the expected design period.
More detail on tests:
- Temperature Stability
- Exposure to light and heat
- Exposure to natural elements
- Chemical Resistance
- Abrasion Resistance
This test method provides a procedure for the determination of shrinkage of geotextile fabrics when exposed to elevated temperatures. The effect of the temperature is expressed as a percentage decrease in area of the geotextile.
A specimen of geotextile is subjected to heat exposure for a pre-determined time period. The factor of shrinkage is determined after exposure by physical measurement.
Exposure to Light and Heat
This standard sets out a method for determining the durability of geotextiles when subjected to degradation due to exposure to light and heat by artificial means.
A geotextile specimen is exposed to the heat and light generated by a high capacity incandescent light bulb. The tensile strength of the specimen after exposure is compared to the parent strength and the resultant loss in strength recorded.
Exposure to Natural Elements
This test method covers evaluating the deterioration in tensile strength and strain after outdoor exposure. The deterioration is assessed as a reduction in strength and strain at failure from the unexposed geotextile. The specific location of the light and weather exposure is made on the basis of a site specific decision between the parties involved.
Geotextile specimens are exposed to the natural elements for a predetermined period of time. After exposure, the tensile strength of the specimens are determined and compared to the parent strength.
This practice covers laboratory immersion procedures for the testing of geosynthetics for chemical resistance to liquid wastes, prepared chemical solutions, and leachates derived from solid wastes.
Geotextile specimens are saturated over a predetermined period of time in a liquid bath of varying PH levels. After exposure, the tensile strength is determined and compared to the original parent strength and the degree of degradation recorded against the different PH levels.
Abrasion resistance is possibly the most important characteristic that a Geosynthetic Sand Container must exhibit. Constant wave action combined with a rough beach sand and sea shell mixture is a highly abrasive force. Underestimating this effect or specifying a geotextile which does not have sufficient abrasion resistance can result in the failure of a GSC structure.
Rotating Drum Method (BAW)
This test is used to determine the abrasion resistance of geotextiles. The test best mimics the action of the sea on the geotextile. The test is performed by fixing specimens of various geotextiles onto the outside face of the rotating drum, filling the inside of the drum with 3 kg of 3 –5 mm stone and 5 kg of 8 – 12 mm stone , adding 15 ℓ of water and sealing of the system. The specimens are exposed to 80 000 revolutions in total alternating direction every 5 000 revolutions. Once complete, the exposed samples are removed, dried and tested for tensile strength and compared to samples of the parent material. The percentage loss of strength is reported. The entire test represents 222 days exposure to wave action at a 10 sec frequency or wave period.