What geotextile to use for drainage

During the arrangement of drainage, a special filter material is used – geotextiles. Strong and environmentally friendly fabric belongs to the group of geosynthetics. The main purpose of the material is the separation of soil layers of different composition and purpose. The fabric prevents them from mixing, but at the same time passes water through itself. Several types of such material are produced. What geotextiles are needed for drainage, we will now figure it out.

Application of geotextile

Geotextile can be called a filter. Passing moisture through itself, but preventing the passage of solid particles, the fabric does not allow heterogeneous soil layers to mix. Due to these properties, the canvas is widely used in the arrangement of drainage systems. They help to divert rain, as well as melt water from buildings, sidewalks and other structures.

In addition to the filtration function, geotextiles prevent the germination of weeds. If the canvas is placed under the decorative layer of the bulk garden path, then water will never accumulate on it and weed grass will never grow. It should be taken into account that there are drainage systems of different types, therefore, the choice of the type of geotextile occurs on an individual basis.

Variety of canvas

The appearance of geotextiles resembles fabric. But her properties are completely different. The cloth differs in durability, high resistance to loadings and mechanical influences.

There are two main types of geotextiles:

• Woven fabric is called geotextile. The material is produced from natural or synthetic raw materials by interlacing fibers. The main purpose of the geotextile is soil reinforcement. The canvas is closed on large slopes to prevent landslides, and is used in the manufacture of geocontainers and other similar structures.
• Non-woven material is called geotextile. It is completely made of synthetic raw materials by combining polymer fibers. The geotextile is used in the construction of drainage systems.

Today we are considering what kind of geotextile is needed for drainage, so we will dwell on the geotextile in detail. There are three ways to produce filter material:

• during the thermal method of production, polypropylene threads are soldered.
• the chemical method is based on gluing synthetic fibers.
• the mechanical or needle-punched method is based on the interlacing of synthetic threads or fibers.

A geotextile made only by one of the considered methods rarely goes on sale. Typically, this type of geotextile is produced using several polymers. This uses a combination of, for example, chemical and mechanical methods.

Which geotextiles can and cannot be used for drainage

First, let’s figure out which material cannot be used for drainage:

• Drainage material such as thermally produced geotextile is not suitable. The soldering of the threads is so strong that the material practically does not let water through. The material is very dense, but it cannot be used instead of waterproofing.
• It is impossible to choose geotextiles for drainage, which contain natural fibers, for example, cotton or wool. Such a canvas will rot in dampness.
• The material made of polyester threads is highly durable and resistant to decay. However, such geotextile perfectly absorbs water, but does not give it away, but keeps it in itself. Such a canvas for drainage is not suitable.

Geotextile made of polypropylene threads is optimally suited for drainage. The fabric is characterized by increased strength, excellent ability to pass moisture, resistance to decay and chemicals.

What are the parameters for choosing a canvas for drainage

When considering how to choose a material for arranging drainage, you must first pay attention to how thick it is. A thin sheet will break through during the movement of the soil, and a thick fabric will quickly silt, which will stop the filtration process. It is optimal when the geotextile used for drainage is of medium thickness.

Now let’s look at the main parameters by which the selected material is suitable for drainage:

• To begin with, for drainage, the density of the geotextile must be selected, guided by the depth to which it will be buried. It is also important to consider the type of soil. For example, when arranging shallow drainage, it is enough to use a canvas with a density of 150 g / m³. On slow-moving soils, when laying drainage pipes, a material with a density of 200 g / mXNUMX is used.³. Where there is seasonal movement of the ground, a web with a minimum weight of 300 g/m is suitable.³.
• For drainage, only geotextiles with high moisture permeability should be laid. This type of material includes a geotextile made of polypropylene threads.
• There is such an indicator as the filtration coefficient. It indicates the amount of moisture that the geotextile can filter per day. For the drainage system, a minimum value of 300 m is allowed³/day.
• In order for the laid geotextile to serve for a long time, it is necessary to optimally select the material for mechanical strength. For drainage, a canvas with a transverse tensile load of 1,5–2,4 kN/m is used, and a longitudinal one is from 1,9 to 3 kN/m.

Often geotextiles for drainage systems are simply identified by their white color.

Rules for the use of geotextiles in the arrangement of drainage

Laying the geotextile is very simple, as the canvas is easily cut with a knife, rolled up, taking the desired shape. To get effective drainage, you need to follow simple rules:

• Being in the heat for a long time under the sun, the geotextile can degrade the filtering qualities. It is optimal to unpack the material immediately before its use and immediately cover it with earth.
• To prevent the canvas from tearing, it must be laid in the trench after leveling the bottom and side walls. The fabric should not be too tight and without folds. If a hole has formed on the geotextile, this piece must be cut off, and then replaced with a new one.
• The width of the canvas is selected so that it can overlap the pipe with drainage backfill. Here you need to make calculations before installing the drainage system. Take into account the cross section of the pipe, as well as the thickness of the backfill. Ideally, drainage is obtained if it is enough to roll out a single piece of geo-textile along the trench.
• To have a better idea of ​​laying the geotextile, let’s take a closer look at the drainage layout. So, a canvas is spread at the bottom of the trench. Its edges should go beyond the pit, where they are temporarily pressed by the load. Crushed stone with a thickness of about 300 mm is poured on top of the geotextile. Next, the pipe is laid and backfilled on top with a similar layer of rubble. After that, the free edges of the geotextile overlap the entire filter system. In the final, the trench is backfilled with soil.

If the laying of the crushed stone geotextile and pipes was done correctly, the drainage system will function properly for many years.

The video talks about geotextiles:

Choosing the right geotextile for drainage is easy. In extreme cases, you can use the recommendations of sellers. The main thing is to strictly observe the technology of laying the material.