Geomembranes and the Control of Expansive Soils

The geomembrane is a member of the family of geosynthetics. It is a manmade fabric, a hydrocarbon compound treated to generally provide a substantially waterproof material. Geomembranes have been used to create a barrier to minimize moisture changes in expansive soils. These moisture changes cause volumetric changes in the swelling and shrinking clays and shales. Expansive soils are found on all the earth's continents with the exception of the polar ones. These soils have been identified in forty of the fifty United States. Damage estimates to transportation facilities, homes, and businesses exceed $10 billion annually in the United States. Case studies using geomembranes examine primarily Texas highways. The work of Wyoming Department of Transportation on more than fifty highway projects is reported. In these and other states the geomembrane barriers have been used horizontally and vertically, often both ways. Mention is made of highway treatment in Israel and railroad lines in China. The past and current impact of the expansive soils on buildings are considered in Australia and the United States. Durability results indicate the geomembrane will last decades. Geomembrane costs have decreased and placement rates have increased. The geomembrane moisture barrier generally can decrease damages caused by expansive soils.