Effect of Chemicals on Engineering Properties of Soil

Abstract

Geotechnical behaviour of fine grained soils is controlled by constituent of soil, type of pore fluid, presence of salts etc. The clay particles having effective size less than 0.002 mm havenegative charges at surface and positive charges at edges.The charged clay surface together with the counter-ions in the pore water form diffuse double layer.The entire system tries to attain equilibrium under weak Vander wall forces.Double layer is influenced by the valency of the counter-ions and the temperature. Use of salt solution as pore fluid generally causes decrease in liquid limits. Salt solutions generally increase the maximum dry density and decrease the optimum moisture content. Increase in unconfined compressive strength is observed with addition of salt in lower concentrations. Permeability generally increased with the addition of salt. When treated with salts in most cases it has been reported that Compression index Cc, Swelling index Cs, and coefficient of compressibility (a v) decreased, whereas coefficient of consolidation (C v) increased as the water salinity increased. In the present paper the effect of presence of salts as pore fluid on engineering properties of soil as reported in literature has been highlighted.