Soil Suction and Behavior of Chemically Treated Clays

Abstract

Expansive clay soils have caused significant damage throughout the world. Chemical stabilizing agents have been used to reduce the swell of expansive clay soils, but the effect of chemical treatment on the matric and osmotic suction of soils has not been investigated previously. Two subject soils were chosen to study soil suction and the behavior of chemically treated clay. One soil, with high swell potential, was from Irving, Texas. The other soil, with moderate swell potential, was from Slater, Missouri. Hydrated lime and KIS (a proprietary solution containing potash and ammonium lignosulfonate) were used as chemical stabilizers. Select physical and chemical properties of these soils before and after reacting with chemical stabilizers were determined. Total suction, matric suction, and osmotic suction were determined with the use of a dewpoint potentiometer (WP4) and an electrical conductivity probe. Matric suction arises from capillary forces, soil texture, and adsorption forces of clay. Osmotic suction results from the balance of salt concentrations in soil water. When the soils reacted with chemical stabilizers, the osmotic suction increased because of the ion concentrations in the soil. Practical methods were used to determine the osmotic and matric suction of natural soils and of chemically treated soils. Soil suction was correlated with other clay soil properties. Practical methods to separate soil suction parameters were used, and the validity of soil suction to predict chemically treated clay behavior was found to be problematic.