The Ultimate Guide to Geotextiles
Geotextiles are used in a wide range of industries, including construction, mining, and agriculture.
The main purpose of the geotextile is to separate the soil from the other materials in order to prevent erosion, allow proper drainage, and keep the soil from mixing with other materials.
They are used both in above-ground and underground projects. For underground applications, they are used to keep the soil in place and prevent it from mixing with other materials while also allowing proper drainage.
For above-ground applications, geotextiles are often used in construction projects to separate different layers of materials.
In many landscaping applications, it is important to provide permeability while keeping soil in place. A geotextile is a perfect solution for this as it allows water to flow through while still preventing the soil from being displaced.
In this ultimate guide, we will go over everything you need to know about geotextiles. What are they, how do they work, why are they needed and how do you choose the right geotextile for your project.
Let’s get started!
What is a Geotextile?
A geotextile is a synthetic fabric that is used to filter or separate soils and aggregates. It supports the soil, prevents erosion, and allows proper drainage.
Geotextiles are members of the geosynthetics family and are made of synthetic materials such as polyester, nylon, or polypropylene.
They have been in use since the 1950s and are commonly used in earthworks, construction projects, landscaping, mining operations, erosion control works.
What are the types of Geotextiles?
Although geotextiles are primarily used to separate different layers of soils and aggregates, they are classified into two types based on the manufacturing process.
Woven geotextiles
Woven geotextiles are made by combining monofilament and multifilament in silk films or yarns.
These filaments can be combined through weaving a variety of types together to create the desired weave pattern, which allows them an almost endless number of possible applications for use as reinforcement against earth tremors or preventing soil erosion.
Woven geotextiles are made from a range of materials, depending on the purpose and pore size opening required. They are typically used to separate soils and to add reinforcement to improve soil textile strength.
Due to their tight and permeable weaving, woven geotextiles are typically not employed for drainage but have a great load-carrying capability. They are typically utilized in highways and parking lots.
Woven geotextiles are available in a variety of weaves, including plain, twill, satin, and leno. They offer a high degree of strength and durability, but also have relatively low permeability.
Therefore, woven geotextiles are preferred for applications where high strength and resistance to erosion are needed. They are typically more expensive than non-woven geotextiles because of their complex manufacturing process.
Non-woven geotextiles
Nonwoven geotextiles are commonly made of polypropylene or polyester fibers by molding small staple-like threads together or molding continuous filament into a thin sheet.
They are typically manufactured using a needle punch process. In this process, a needle interweaves the numerous threads together to form a single solid material layer.
Non-woven geotextiles can also be manufactured via chemical or thermal bonding. This manufacturing method joins perpendicular threads in a random orientation, resulting in high porosity and permeability.
They are typically thinner and flexible and lack durability and strength compared to woven fabrics. However, non-woven geotextiles are typically used for drainage applications where permeability is more important than strength.
Non-woven geotextiles are typically cheaper than woven geotextiles because they don’t require the weaving process which is costly. The main difference between the woven and non-woven geotextiles is the pore size and fiber type.
Woven geotextiles have a plastic-like feel and look, whereas non-woven geotextiles have a fuzzy feel and appearance. Typically, woven geotextiles are referred to by their tensile stress while non-woven geotextiles are referred to by their weight in grams per square meter.
The reason for the weight of woven geotextiles is hardly ever specified because they are typically used to provide reinforcement and separation which their weight is not a major concern.
Why are key applications geotextiles used for?
There are many good reasons why geotextiles are used and the key applications of geotextiles are as below.
Separation
Geotextiles are used to separate soil layers in order to maintain or improve the integrity of both materials. This is important for applications where different types of soils and aggregates are being used, as it prevents them from mixing together.
Because different layers of materials are placed to serve distinct goals. By keeping them separate, you can avoid potential problems and ensure that each installed layer is working to its full potential.
In many construction projects, a layer of geotextile is placed between the sub-grade and the base course to prevent the mixing of soils and keep them in place. This also allows water to flow freely while keeping soil in place.
Reinforcement
Geotextile membranes are extensively employed as reinforcing materials in construction and engineering applications. Because of their high tensile strength, geotextiles can be used to increase ground stabilization and ground reinforcement.
They are often placed over weak or unstable soils to prevent them from eroding, which can cause serious damage downstream. Geotextile reinforcement is also used in earth-retaining structures and bank protection systems for the same reason.
Geotextiles are also often used to strengthen embankments and roadways built on unstable soils, as they allow for steeper embankments to be erected without fear of collapse.
Filtration
Geotextiles are often used as filters for in-situ soil treatment. This is done by placing geotextile in between the contaminated material and the leaching system, which will filter out any pollutants before they can harm surrounding areas.
This method of filtration is useful to treat groundwater that contains high concentrations of heavy metals or other pollutants. By using geotextiles as filters, the leaching system is able to clean groundwater more efficiently and reduce environmental impact.
Drainage
Geotextiles are often used to manage groundwater seepage and surface runoff. They do this by acting as a drainage layer, which allows water to pass through the fabric but prevents soil from passing through it.
This is important since too much moisture can damage structures or create an environment for mold growth.
Cushion
Geotextiles can also serve as a cushion above or below the soil to prevent infrastructure from being damaged by soil settlement.
This is especially important for construction projects where the ground below must be excavated and replaced with new material, as it allows time to replace worn-out infrastructure without causing additional damage.
Geotextiles can be used as a stabilizing membrane to keep soil from shifting and prevent it from moving vertically after construction is done. By doing so, it can protect structures from collapse and erosion.
What are the example uses of geotextiles?
Geotextiles are used in a wide variety of projects and can be used in various settings.
They are most commonly found in the construction and civil engineering sectors, but also appear in other applications such as mining and agriculture.
Here are some specific examples of where geotextiles are used:
Earth retention and bank protection
In these applications, geotextiles are used to prevent soil from being eroded away by water or wind.
This is done by reinforcing the soil with a geotextile membrane, which will increase its stability and prevent it from collapsing.
Earth-retaining structures and bank protection systems are commonly used in areas with high levels of rainfall or wind, where the soil is prone to be blown away.
Green roof applications
Green roofs are vegetated roofs that are installed to reduce carbon emissions and manage stormwater runoff.
A geotextile membrane is typically used below the soil of these roofs, where it allows water to drain through but keeps soil in place. By doing so, geotextile membranes are able to prevent erosion and protect structures from being damaged.
Flood protection
In areas that are prone to flooding, a layer of geotextile can be placed on the surface of the soil. This will help to keep the soil in place and prevent it from being washed away by floodwaters.
Environmental engineering applications
Geotextiles are also used to filter groundwater in soil remediation efforts that focus on cleaning up contaminated soils.
This allows for more efficient treatment of the site while reducing environmental impact and preventing damage to surrounding areas, which is an increasing concern due to growing pollution levels worldwide.
Earth dikes
Geotextiles are used to build earth dikes. They provide an excellent layer of protection against erosion, which is especially important if the soil along riverbanks or coastlines has been weakened by extended exposure to water currents and waves.
Railway embankments
A geotextile can also be used to build railway embankments. The material provides a strong, durable structure that is resistant to water and helps prevent landslides from occurring on steep slopes along the tracks.
Coastal applications
In coastal engineering, a geotextile can be used to protect beaches and marshes from being eroded by waves and tides.
This is done by placing a geotextile membrane between the soil and the beach, which prevents waves from washing away loose material.
How to choose a geotextile for any project?
When choosing a geotextile, it is important to consider the specific application that you have in mind. The three most important factors to consider are:
Intended application
Not all geotextiles are created equal. Some are designed for specific applications, such as stabilizing slopes, filtering water, or preventing soil erosion, while others are used for general applications.
Knowing what you need the geotextile for will help ensure that you choose a material with the right properties.
Therefore, carefully read the product description to understand your selected product’s capabilities in relation to your intended application.
Performance requirements
Even if you are using the right type of geotextile for a specific application, there are different grades available with varying degrees of performance.
Geotextiles have different performance requirements based on the material they are made of, their permeability levels, and the amount of stress they will be subjected to.
For example, two different soil stabilization applications may require different performance levels.
Therefore, it is important to consider what characteristics you want the geotextile to have, and understand how different grades of a specific product can meet those requirements.
Chemical and environmental resistance
Geotextiles need to be resistant to both chemicals and the environment in which they will be used.
For example, a geotextile that will be used in an area with high occasional chemical spills should be resistant to certain chemicals, while a geotextile that will be used in an area with high levels of saltwater or other corrosive materials should be resistant to these too.
Environmental impact
Not all geotextiles are created equal in terms of their environmental impact, either. Some products are made using recycled materials, while others are made from polymers that deplete the earth’s virgin materials.
Choosing a geotextile that has recycled content, and low embodied energy can help reduce the environmental impact of your project.
Water permeability
Geotextiles can be made from materials that either allow water to pass through them or block water entirely.
Yes, there are permeable and almost impermeable geotextiles, and the type you select will depend on your intended application.
However, different permeable geotextiles have different permeability levels. For example, a geotextile with high permeability will allow water to pass through it faster than one that is made of a material with low permeability.
Therefore, carefully read the product description to understand your selected product’s water permeability levels and what they mean in terms of your intended application.
We have already mentioned geotextiles are available in both woven and non-woven fabrics.
Woven fabrics are stronger and more durable, but they also have a lower permeability rate. Non-woven fabrics are less durable but have a higher permeability rate.
Width and length of the roll
Geotextiles are typically available in widths of up to 12 meters (40 feet) and lengths of up to 100 meters (330 feet).
When considering all of these factors, it is important to work with a supplier that understands the size-specific needs of your project.
How to install a geotextile?
The installation of a geotextile is essential if you want to get the most out of the product. Different geotextiles have different installation methods, so it is important to read the product instructions carefully.
In general, a geotextile should be installed in such a way that:
Prepare the surface where the geotextile will be installed.
Geotextiles should be installed on a clean and level surface. This will help ensure that the product will perform as intended.
If the geotextile will be used in an area with slopes, it is important to ensure that the slope is gradual (less than a five percent grade), or else water could pond on the geotextile and damage it.
Install the geotextile correctly.
Once the surface is prepared, it is time to install the geotextile. This is typically done by unrolling the product and overlapping the edges. Be sure to follow the specific installation instructions for your chosen product.
Securely fasten the geotextile in place.
Some geotextiles come with fasteners to secure the edges of the geotextile, while others must be staked into place. The entire surface of the geotextile is in contact with the soil or material it is designed to protect.
Most geotextile is held in place by a layer of geogrids or another type of material that prevents them from moving about and bunching up.
Whatever method you choose should balance ease-of-installation with durability and long-term performance requirements.
Avoid damaging or puncturing the geotextile.
When geotextiles are installed, they are repeatedly subjected to dynamic bulk loading of armored units, which frequently exceeds the static design values by several orders of magnitude.
That means that if your geotextile is not installed properly, it will start to fail in ways that will negatively impact the project’s success.
The geotextile is rolled out on the top of the subgrade and must be initially secured along its lateral edges to ensure that it will not shift. Once this initial step is complete, the rest of the geotextile is ballasted with sand or other granular material.
To reduce the likelihood of the aggregate sliding over the geotextile and causing damage to the material, the aggregate should be back dumped from a lower height.
The installation crew should use a shovel or similar tool to work the aggregate into the geotextile and ensure good contact between the two.
Once the geotextile is in place, the ballast crew should backfill with aggregate to a depth of around 100mm (or whatever level it has been designed for).
The next step involves compaction. The installation crew uses a light-duty pneumatic roller or vibrating plate compactor to compress all layers within 50 mm of the geotextile.
The geotextile should never be used as the sole drainage layer; it must always be installed over a suitable drainage medium.
Conclusion
Geotextiles are an essential part of a versatile range of projects. They play an important role in soil stabilization, erosion control, drainage, and many more applications.
There are different types of geotextiles for different applications, so it is important to choose the right one for your project. Most importantly, geotextiles should be installed correctly ideally by a qualified contractor.
