Geotextile fabrics are typically constructed using polypropylene, polyester, or nylon and are available in either woven or non-woven designs. This separation of differing soil types maintains flow rates of soils used as drainage layers and minimizes settlement from finer materials filling in more coarse materials. Geotextile filter fabrics are also used for separating differing soil types in below grade enclosure applications. Although marketed to be used with excavated soils during backfill in lieu of a granular drainage layer, it is recommended that a full system approach be used in applications where water leakage is not tolerable a full system approach should include both a synthetic drainage layer and granular drainage layer. These systems are advantageous in their lightweight design and cost effectiveness. In general, drainage core widths of 1/4 to 1/2 inch provide drainage flow rates 3 to 5 times the rate of commonly used natural backfill materials. Many drainage mats also include a polyethylene sheet backer to uniformly disperse the loads imposed on the membrane and reduce the potential for damage caused by non-uniform profiles (dimples) in the composite core.ĭesign considerations include selecting an appropriate design to achieve the required flow rate. The fabrics are available in various forms including non-woven for clay type soils and woven or small opening geotextiles for sandy or high-silt type soils. The geotextile fabrics retain sand, soil, concrete, or grout allowing water to migrate into the free draining core. The plastic composite "dimpled" drainage cores are available in various configurations and are typically constructed using polypropylene, polystyrene and polyethylene. Prefabricated Synthetic Drainage Layers-These products consist of a combination of plastic composite drainage cores with adhered geotextile fabrics. Gap-grading the sand provides uniform grain size, which accelerates drainage flow rates. Graded pea gravel refers to naturally rounded stone between 3/16 inch and 3/8 inch in diameter.
0 Comments
Leave a Reply. |