Use of geotextiles and geotextile-related products

The use of geotextiles is recommended when the subgrade has a very low or low carrying capacity, CBR 2% or 2%-5%, respectively. 

The positive effect of the use of geotextile is documented by many field studies as well as comprehensive researches, namely. Potter and Currer (1981) and Robnett and Lai (1982). The measured surface deformation on the unbound layer laid over a subgrade with CBR 2% was much lower when a 450 g/m polypropylene geotextile with a tensile strength of 10.5 kN/m was used (Potter and Currer 1981). 

A more effective result of the increase in subgrade bearing capacity is achieved with the use of geogrids, since they act as a kind of reinforcement. A geogrid can be used either on its own or in combination with a geotextile. 

Geogrids usually consist of polyesters or woven fibres coated with PVC. The square mesh created has various dimensions that typically range from 10 mm x 10 mm to 50 mm x 50 mm. The mesh size to be used is determined by the size of aggregate particles of the over-lying layer or of the layer in which the geogrid is to be embedded. 

Geogrids have a much higher tensile strength than geotextiles values usually range from 35 to 100 kN/m. 

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