Silty soils characteristics

The physical properties of soils important in corrosion are mainly those that determine the permeability of the soil to oxygen or air and to water. The particle size distribution of the soil is an important factor with respect to aeration and moisture content. In coarse texture soils such as sands and gravel, where there is free circulation of air, corrosion approaches the atmospheric type. Clay and silty soils are characterized in general by fine texture, high water-holding capacity, and by poor aeration and poor drainage. Variations in these characteristics within the same soil environment lead to higher corrosion rates comptired to that experienced by atmospherically exposed materials. 

The characteristics of a soil determines the cost-effectiveness of the recycled product. Sandy, silty, and cobble soils are more suitable for recycling into asphalt concrete. 

These soils have a high proportion of clay and silty material - ustrally over 60%, at least half of which is pttre clay. These so-called heavy soils include the clay, silty clay and sandy clay textirres. It is the clay content which is mainly responsible for their specific characteristics. Particles of clay have very important properties ... 

The permeability of frozen ground barriers was directly measured in a recent laboratory project for the US Department of Energy. The soils were uncontaminated samples from DoE nuclear reservations a coarse silty sand from Hanford, Washington, and a clay soil from Oak Ridge, Tennessee. The test fluids were dilute aqueous solutions of potassium chromate K2CrO ) trichloroethylene (TCE) and radioactive cesium ( CsC/2), concentrated CaC/2 brine, and pure decane. The choice of soils and chemicals provided a sampling of the characteristics of liquid contaminants at many of the DoE s leaking nuclear waste sites. 

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