Geotextile for Road Reinforcement and Separation

Road construction commonly suffers from settlement, subsidence, rutting and so on, which is why geotextile reinforcement and separation matters. This happens because the fill used in the road can mix with the subgrade. This mixing causes typical road damage because there is no separation layer. It gets worse when the subgrade cannot carry the load, the fill is poor, the fill height is insufficient, and so on. A separation layer stops the fill from sinking when loads are applied at the road surface. The most common geosynthetic product for this problem is geotextile, which comes in two types: woven geotextile and non-woven geotextile.

Below is an illustration of road construction without geosynthetics as a separation layer:

The illustration above (figure 1) shows the fill layer (base / sub-base) settling as the material sinks into the subgrade. In reality the settlement will not be as even as in the illustration, because soil is heterogeneous. With this settlement, the road surface needs patching, which is far from cost effective.

Below is an illustration of road construction using geosynthetics as a separation layer:

The illustration above (figure 2) shows geotextile used as a separation layer. With geotextile as a separator, settlement, road damage and patching can be reduced because the base/sub-base fill does not mix with the subgrade. Besides separation, geotextile also helps reinforce the road structure, because it has tensile strength, a membrane effect and adds friction to the road fill.

Friction effect: occurs with geotextile and geogrid, where friction between the geosynthetic and the soil prevents the soil from shifting.

Membrane effect: occurs when geotextile and geogrid deflect under load. This curvature generates a force that resists vertical loading.

The use of geotextile for reinforcement and separation in road construction has established CBR criteria (table 1) and GSM values: 250 GSM woven geotextile and 400 GSM non-woven geotextile. The GSM value can be adjusted to site conditions and the application. To make sure you get an ideal and cost effective result, consult with us.