w
2w
SHUare also characterised by high dimensional stability and tensile modulus at very low elongation.
Because of the large openings, they cannot be used in filtration and as moisture barriers but are
quite useful for the purpose of separation and reinforcement. They can be used in road
pavements, or in improvement of bearing capacity.
q
## are a continuous membrane type linen and barrier composed of asphaltic,
polymeric or a combination There of materials with sufficiently low permeability so as to
control fluid migration in a geotechnical engineering-related man made project, structure or
system.
q
#
consist of combinations of geotexites, geogrids, geomembranes and/or other
materials. In geocomposites best features of different types of geosynthetics are incorporated
in such a way that the joint action of the materials provide optimal performance in a particular
situation.
e
2 $
A geosynthetic can improve the load carrying capability and reduce
rutting when constructing roads over weak soils. The geosynthetic provides a separation
barrier to prevent fill from punching into the subgrade under construction traffic, as shown in
Fig. 21.1. The subgrade can develop its full bearing capacity and the fill can better distribute the
loads from traffic. The geosynthetic may also provide filtration and drainage functions if
required.
p 2PII q "# 22 % Geosynthetic used under railway track, as shown in Fig. 21.2 may provide for additional
roadbed filtration, lateral permeability strength and modulus improvement, and separation of
subgrade and ballast.
e 2y When installed between the old and new asphalt layers, a geotextile helps
retard reflective cracking and improve the overlay service life. The geotextile absorbs the tack
coat sprayed on the surface of the old pavement, formulating a permanent moisture barrier.
This barrier created by the geosynthetic protects the subgrade from water intrusion and subgrade
strength loss. Pavment service life is extended, maintenance costs are reduced, and costly
resurfacing is postponed considerably, when compared to conventional repaving techniques.