Geosynthetics are amazing materials. They drain, contain and filter. They separate as well as hold together. They work underground and underwater, on mountainsides and on rooftops. According to the International Geosynthetics Society, the words geotextiles and geomembraneswere coined only about 30 years ago, at the first International Conference on Geotextiles, in Paris. Since then, we have added geogrids, geonets, geosynthetic clay liners, geofoam, and geocomposites. These materials are made of polypropylene, polyester, high-density polyethylene (HDPE), linear low-density polyethylene (LLPDE), and polyvinyl chloride (PVC), to name a few. All are flexible and durable.
Geotextiles are one of the largest groups of geosynthetics. Their fibers are either woven, knitted, needle-punched, or matted together into fabrics. They’re porous to varying degrees and are used for separation, reinforcement, filtration, and drainage. Geomembranes are another large group of geosynthetics. These are relatively thin, impervious sheets of polymers. They’re often used for linings and covers to contain liquids or vapors in landfills, reservoirs, and canals.
Geogrids are stretched sheets of polymers that form open grids. Uniaxial geogrids stretch in one direction and have rectangular apertures. Biaxial geogrids stretch in both directions and have virtually square apertures. They can be filled with soil, aggregate, or concrete and almost always are used for reinforcement and to improve load-bearing capacity.
PHOTO: CAPITOL GREEN ROOFS
