Geogrids form a distinct category of geosynthetics designed for reinforcement. These products are characterized by a relatively high tensile strength and a uniformly distributed array of large apertures (openings between the longitudinal and transverse elements). The apertures allow soil particles on either side of the installed sheet to come into direct contact, thereby increasing the interaction between the geogrid, aggregate and some soils. Also, the apertures ensure vertical drainage of a reinforced free-draining aggregate/soil.
The geogrid elements vary in polymer type and cross-sectional dimensions. They can sometimes change shape and dimensions within their length. Geogrids are either integrally manufactured (punched and drawn sheets; or extruded), ultrasonically or adhesive bonded strips, or joined in a knitting or weaving process and then coated. Polymer types include polyethylene, polypropylene or high tenacity polyester that has been coated.