These are a flat geosynthetic made of polypropylene or polyester fibres bonded mechanically – by needling (or stitching) or thermally by welding. It is used as a separation of weak embankment subsoil to improve its stability and accelerate consolidation. It is used to create separating layers between the soil or aggregates of different grain sizes, as well as base layers to hold the soil under geomesh, geogrids, and gabions, in the construction of reinforced slopes and embankments. It is used for riverbank protection, coastal protection, land reclamation and in the construction of embankments and reservoirs. It is used to secure drainage systems in order to protect them from clogging with fine-grained soil. It provides long-term protection of geomembranes in the construction of landfills, tunnels and reservoirs. Due to the functions performed by geotextiles and the engineering areas in which they are used, several major groups of geotextiles can be distinguished.
Geotextiles, whose main function is filtration, such as retaining solid particles while allowing water to flow freely between two different soil layers. They are mainly used for the construction of French drains (stone drains), the wrapping of drainage pipes, as a filter layer to reduce internal erosion in hydraulic engineering and under gabions and geogrids. These functions are best fulfilled by thin geotextiles with optimum pore dimensions and high water permeability in the direction perpendicular to the plane. These parameters determine the incidence of colmatisation (clogging of soil pores). In many cases, it is also important that they have specific tensile strengths.
GEOTEXTILES FOR FILTRATION AND SEPARATION
The broadest group of geotextiles performing separation and filtration functions. They permanently prevent the mixing of the different substrate layers, making it possible to reduce the thickness of the base layers in substructure construction and extend their service life. The filtering properties of the geotextile allow for much faster soil consolidation by filtering out water. The selection of geotextiles depends on the existing conditions and the effects needed. The main areas of application are the separation of individual construction layers of temporary roads, access roads, forest roads, permanent roads, airports, motorways, parking lots, storage yards, playing fields, embankments, berms, breakwaters and other earth structures.
GEOTEXTILES FOR DIFFICULT CONDITIONS
These are special geotextiles that combine many features of different geotextiles. At the same time, they provide high mechanical and hydraulic performance. These are generally two-layered geotextiles, one of which provides high tear and puncture resistance, while the other is a filter that retains the fine solids while ensuring the free flow of water. Such properties allow geotextiles to be used in areas where they are vulnerable to damage during installation or operation. These may include the stone ripraps used in the protection of seashores or breakwaters.
PROTECTIVE AND DRAINAGE GEOTEXTILES
These are thick geotextiles with high puncture resistance and the ability to transmit water or gases in a plane. They are used as geomembrane protection and drainage in the construction of reservoirs, landfills, storage yards, and tunnels.