Geotextiles

Geotextiles are permeable engineered fabrics placed between soil layers to separate, filter, drain, reinforce and stabilize. Their most basic job is keeping dissimilar materials from mixing — stopping soft subgrade from pumping up into a stone base, or fines from clogging a drainage layer — while still allowing water to pass through freely. That combination of strength and permeability is what distinguishes them from a plain sheet material.

They come in two broad constructions. Woven fabrics are made from flat or round yarns interlaced for tensile strength, and are used where the fabric has to carry load and hold aggregate in place over weak ground. Nonwoven fabrics are made from fibers bonded mechanically or thermally into a felt-like sheet, and are used where water flow and filtration matter more than strength. Typical applications span roads and parking areas, drainage systems, riprap and shoreline protection, embankments, and any situation where a layer needs to stay separate from the one beneath it.