If the geotextiles for any reason be damaged or torn , the tear should not increase in size under normal loads.
When the base course is loaded the aggregate is pressed against the geotextiles . The geotextiles , therefore , must be strong enough to resist puncturing . It is worth to mension that the heavier geotextiles are more resistant to puncturing and bursting.(22)
A geotextile is ,by definition, permeable , and it therefore exhibits the ability to transmit water in a direction normal to its plane. (18)
Permittivity or cross- plane water flow is an important index test for filtration. The mechanism by which water moves through the geotextile is characterized by the permittivity of geotextiles. (4)
Two vital factors in the performance of geotextiles as filters are the size and distribution of the holes or pores in the geotextile. All geotextiles have pores which allow the transmission of water.
Any water in the base course must be able to drain out through the geotextiles, otherwise, the base may become unstable. That means , the water permeability of the geotextiles should be equal to or more than of the subgrade. (22)