Coastal & Waterways
Filtration & Separation
Frequently Asked Questions
What is a Geotextile?
A permeable highly durable synthetic fabric general used in Civil Engineering and Building projects such as road and car park construction to stabilise loose soil and prevent erosion. TERRAM geotextiles are highly permeable nonwoven needle punched and thermally treated synthetic fabrics made from polypropylene used to separate, filter, reinforce, protect, or drain engineering soils. Typical uses include preventing intermixing of granular sub-base and subgrade layers, drainage and bedding materials. TERRAM geotextiles help reduce wastage/loss of expensive imported granular materials, improve structural performance and extend the life of the pavement/road/rail track.
What is a TERRAM Geotextile used for?
TERRAM geotextiles are predominantly used for separation and filtration of fill materials preventing intermixing and extending the service life of unbound materials. TERRAM geotextiles can also be used to provide puncture resistance and reinforcement in certain applications.
What is the difference between a woven and nonwoven (TERRAM) geotextile?
A woven geotextile is manufactured from continuous filaments or strips of synthetic material which are woven together to form a uniform sheet. A woven geotextile has a very uniform pore size which varies under load making them less suitable for filtering anything other than clean single sized soils/fills. Nonwoven geotextiles are a tangled web of fibres mechanically and/or thermally bonded together to form a non-uniform random web. Nonwoven TERRAM geotextiles have a wide range of pore sizes which make them ideally suited for filtering many different types of fill materials including well graded materials even under varying load conditions.
How important is the GSM (grams per SQM) weight of a TERRAM Geotextile?
The most important properties which affect performance of a geotextile are permeability, pore size, puncture resistance and tensile strength. GSM weight of a geotextile is a useful parameter for the purposes of internal quality control. TERRAM geotextiles often achieve the required functional performance at much lower weights compared to other geotextiles due to the exceptional quality control and state of the art manufacturing process.
What grade of TERRAM Geotextile do I need?
TERRAM T1000GT standard geotextile is the most commonly specified separation & filtration geotextile in the UK and is fit for most but not all conditions. Ground conditions (type of soil, strength and permeability), type & size of aggregate fill, size of compaction equipment, traffic loadings (weight & frequency) will all affect the grade of TERRAM geotextile required. Please refer to TERRAM specification, design and installation guidance for more details.
What is the design life of a TERRAM Geotextile?
When designed, installed and maintained in accordance with the published literature most TERRAM geotextiles are sufficiently durable to achieve a design life of at least 100 years in most typical soil conditions. Please refer to DoP (Declaration of Performance) certificates for specific product grades which state the anticipated design life based on independent durability testing.