In this usage geotextile applies in one or more main roles according to the condition of the place, in the sub grade separating and stone materials and granules, in the filtration, water geotexti le, whether pass the under pressure flow causes by dynamic power or the instant flow of itself with filter and prevent the entrance of smooth soil into the foundation stone layer (Aggregate) and drain layer; in the role of making firm, it causes the finning of the sub grade smooth materials (especially CBR>3) and increases the CBR rate very well and will prevent of sinking the foundation stone materials and granule materials into the smooth and humid sub grade with distributing the area and local pressure.and improves the draining role in the road .
The main spoiling source in the road carpeting is injecting the unwanted water into the structure by the extant split on the carpeting. During making or refreshing the highway carpeting .road.airport band.parking places, cloth annexing between tack coat and new asphalt layer, make the effective humid dam and protect the under foundation in front of penetrating the surface water. [ n this usage, geotextile has two mechanisms for act improving of the coat . First, as the middle layer with pressure absorbing will prevent the diffusion of the reflective cracked of the old coat to the new coat and or will delay it , and second, as the anti humid layer will prevent the entrance of the surface 1 iquids and heaven descending through aphalt split into the under layer and making humid the sub grade and follow that prevent the sub grade weakness and interruption.
The usual way which is used for the cracked road restoration is AC coat, this act will cover the splits and after replacing the coat, any lateral or liner road movement causes the spread of last coat splits to the new coat and events the reflective splits.This movements causes laminating and lacerating and cutting across the reflective sp I its and makes a way for penetrating the surface waters to the foundation layer and sub grade. Under the new AC coat , geotextile can make traction solidity for repelling the received pressures of the last coat. move. Geotextile as the middle layer works in repelling the pressure which caused by the horizontal and vertical splits dipping geotcxtilc with asphalt and bitumen creates the impermeable layer than surface waters, because of affinity and relation the polymer fibers with oil materials, bitumen absorption and tack coat connection to the geotextile layer done very well .