1. PHYSICALLY: particles of ground adhere to wire or are imprisoned by them;
2. CHEMICALLY Existence of precipitates
3. BIOLOGICALLY
development of algae

1) Basic mineral filling
This type of filling is presented in the form of an accumulation, most frequently argilo-muddy, in which the fibres appear crimped. It is in continuity with the ground in place and of very local origin.
Basic filling occurs with the installation of geotextile or, a little later against a ground with water content superior with the liquid limit.
It is primarily due to the nature of the ground support, in its hydrous state, its facility of dispersion and the conditions of setting in place.
The coarse materials do not appear to give of basic filling, contrary, in fact muddy clays enter most easily in semi-suspension in the geotextile ones.

2°)internal mineral filling
It can be either argillaceous, or coarse

a) Argillaceous
I.e. made up of clay and very fine silt. According to the throughput speed of the fluid through the geotextile one, this one can collect particles of size lower than those of the pores of surface. During their progression, the nets of fluid undergo many changes of management in the channels of variable section, which can cause the stop by deposit of the solid particles conveyed with the fluid.
It is initially formed a deposit around fibres in the form of a film, thick with more few tens of microns (sleeving).
In the second time, argillaceous bridges appear between fibres. At the places where the fibres are very brought closer, the bridges multiply and clays invade all space interfibres gradually from where formation of argillaceous cluster in which the fibres are crimped.
The presence of layers of very fine fibres and also very brought closer can support this process.
At the more advanced stage of internal filling, the preceding clusters are connected by argillaceous bridges. The morphology of filling takes the spongy or alveolar form then.
In the case of woven with strips or fibrillated, because of the proximity of fibres inside wire and wire between them, the stage of a total filling is quickly reached.
Let us note that the typical structure of internal sponge filling translates a state of balance between the alluvial deposits (cluster of ground brought by water) and the circulation of water inside the geotextile one.
This makes it possible to account for the strong residual permeability the geotextile ones judged clogged on the morphological level.
b)Coarse
This one is made up of grains of average sand silts, more rarely, wedged between fibres. Often, this filling comes from material of covering.

3)Higher mineral filling In this filling, the materials come from the argilo-muddy matrix of the ground of covering. One can consider this type of filling as the result of the fall of dust or particles not stabilized present in material of covering at the moment of his spreading or during the first scrubbings of the adjacent layer at the geotextile one. This closing partial of the pores by the sand grains on the higher limit of the textile is also called Oestruction.

4) Space layout
Three fibre layouts can retain the particles is

1. At the surface of fibres
2. In a rather broad space (cave)
3. In a bottleneck (restriction)

These sites of deductions of the particles are present in the majority of the membranes non-woven materials available for the drainage and earthworks. The nature and the dimension of fibres, the number of fibres per unit of volume, the percentage of void and the thickness of the membrane, the average diameter of the channels offered to the flow of the fluid are some of the parameters which differentiate the membranes.
In the case of geotextile having a very low thickness (woven), it is possible to idealize the various modes of retention and filling. In consequence of their low thickness, one will be able to compare them to sieves.
In this case, the pores of geotextile are comparable to throttlings. The passage of this obstacle is enough to make cross the geotextile one, while in the case of thick membrane, the particles must walk on through irregular channels of the geotextile one.