What are geotextiles?
Geotextiles are woven, nonwoven or knitted permeable textiles made from synthetic polymers and sometimes natural fibres like jute or coir. They are commonly used for ground engineering – for infrastructure including roads and railways or for erosion control, drainage and soil stabilisation.
Specifically, the textile Institute defines them as a “permeable textile material used for filtration, drainage, separation, reinforcement and stabilisation as part of civil engineering“.
The history of geotextiles
Materials that function as geotextiles go back as far as humans have been building structures. Mud, clay and brick homes were reinforced with matted reeds or straw for stabilisation. For example, these techniques can be seen on ancient constructions like the great wall of China or the remains of Dur – Kurigalzu in modern day Iraq.
Woven geotextiles have been used in the UK since the 1930s, where woven jute fibres were used in highway construction. Later, this was expanded upon in the 1950s where permeable fabrics started being used underneath concrete block revetments. These became nylon in 1956 where they were used by engineers in the Netherlands as part of the Deltawerken – the construction of dams, dykes and flood defences that protect the Netherlands to this day.
Most modern geotextiles are polypropylene or polyethylene, and come with improved structural properties. As a result, their use has spread throughout the construction sector and in the 1990s geotextiles were the fastest growing market in the industrial fabrics industry.
Different types of geotextiles
Knitted, woven or non woven?
Non woven geotextiles have fibres that are randomly arranged forming a felt-like mat. This tight knit fabric provides excellent puncture resistance with high permeability for filtration and drainage. They have a lower tensile strength than woven products.
Woven geotextiles are made with linear and horizontal threads, interwoven to form a fabric. Woven geotextiles are used for high strength applications like structural reinforcement or separation, where filtration or water flow is less important. They are stronger but less elastic than other geotextiles and can break if they are elongated during use.
Knitted geotextiles are less common than the other types and are made with interlaced loops. These can open and deform depending on the direction they’re pulled, making them capable of elongation without compromising strength.
What are they made from
Polypropylene (PP) is the most common geotextile material. It provides good chemical and UV resistance and is durable at light weights. Polypropylene is also hydrophobic and comes at a low cost.
Polyethylene (PE) is usually used in the form of HDPE. It has higher chemical resistance than Polypropylene and is durable for aggressive environments like landfills.
Polyester (PET) used in high strength woven geotextiles due to its long term creep resistance and stability at high temperatures. Often found in soil walls, steep slopes and high load applications.
Natural fibres like Jute or Coir are mainly used for temporary installations or biodegradable solutions. Environmentally friendly, they can promote vegetation growth and contribute to low carbon footprints.
Geotextile Applications
Geotextiles are used for separation, filtration, drainage, reinforcement and protection. They help maintain stable foundations, improve soil performance and manage water. Uses include separating subgrade and stone bases in roads, foundations, embankments and reinforced soil structures while promoting drainage to prevent waterlogging and damage.
- Separation – preventing soil layers from mixing, like gravel and soft subgrade helps maintain structural stability for foundations.
- Filtration – geotextiles act as permeable barriers, allowing water to flow through while trapping soil in place. This prevents clogging drains, soil loss and erosion.
- Drainage – moving water along the plane of the geotextile, directing it into perforated pipes or away from sensitive structures.
- Reinforcement – providing stability and increased load bearing by distributing loads across their surface while preventing lateral spreading of soil.
- Protection – geotextiles can shield underlying structures from puncture, abrasion and erosion – especially in coastal works or landfills.
Emerging trends and where the market is leading
Sustainability
There’s been a push towards circular economies – using recycled polymers, as well as post consumer plastics that are designed for recyclability at the end of their life cycle.
Bio degradable and non plastic synthetic geotextiles have also become popular, reducing the amount of pollution released into ecosystems.
Smart Geotextiles
Smart geotextiles can integrate sensors and conductive fibres to detect moisture and damage in real time for critical infrastructure.
Green Infrastructure
Hybrid systems can combine geotextiles with natural systems to create greener, performance engineered drainage systems like rain gardens and swales.
Read more about best practice construction and design on the Foundations blog: