Geonet is a polymeric geosynthetic consisting of integrally extruded, intersecting ribs that form an open net structure with high in-plane flow capacity. Unlike geogrids, which reinforce, a geonet’s function is drainage: conveying liquids or gases within its own plane while transferring load between the layers above and below.
Structure and materials
Geonets are almost always extruded from high-density polyethylene (HDPE) for chemical resistance and creep performance. Two forms dominate: biplanar geonets with two sets of overlapping ribs, and triplanar geonets with a central rib layer that maintains flow capacity under high compressive stress. Transmissivity — the in-plane flow rate — is the governing design property, tested under the anticipated normal load and gradient.
Functions and applications
Typical applications include leachate collection and leak detection layers in landfill base linings, gas venting beneath capping systems, drainage behind retaining walls and bridge abutments, sub-surface drainage beneath podium decks and green roofs, and groundwater pressure relief behind basement walls and tunnel linings. In each case the geonet replaces a much thicker granular drainage layer, saving excavation, aggregate and carbon.
Geonet vs geogrid vs geocomposite
The three are often confused. A geogrid has large apertures and high tensile stiffness and is used to reinforce soil. A geonet has small, dense apertures and is used to drain. A drainage geocomposite is a geonet (or cuspated core) factory-bonded to geotextile filter layers on one or both faces, preventing soil particles clogging the drainage core — the form in which geonets are most commonly installed.
Related ViaCon solutions
ViaCon supplies drainage geocomposites, geotextiles and the wider geosynthetics family for infrastructure projects. See our GeoTechnical Solutions. Related glossary entries: geocomposite, geomembrane and geotextile.
Frequently asked questions about geonet
What is a geonet?
A geonet is a polymeric geosynthetic made of integrally extruded intersecting ribs forming an open net. Its function is in-plane drainage — conveying liquids or gases within its own thickness — in applications such as landfill linings, retaining wall drainage and podium decks.
What is the difference between a geonet and a geogrid?
They look similar but perform opposite roles. A geogrid has large apertures and high tensile strength and reinforces soil or aggregate. A geonet has a dense rib structure with high in-plane flow capacity and drains liquids or gases; it contributes no significant reinforcement.
What is a drainage geocomposite?
A drainage geocomposite is a geonet or cuspated drainage core factory-bonded to geotextile filters on one or both faces. The geotextile keeps soil out of the core so the drainage path stays open for the design life. It is the most common way geonets are supplied and installed.
Where are geonets used?
Main uses are leachate collection and leak detection in landfills, gas venting under caps, drainage behind retaining walls, abutments and basements, and drainage layers beneath podium decks and green roofs — anywhere a thin geosynthetic can replace a thick granular drainage layer.