Stiffness Response Of Chemically Stabilized Sulfate Rich Soil Via Resonant Column Test

Abstract

Stabilization of expansive soils using lime and cement additives have been used by practitioners over the last few years. However, recent heaving and premature pavement failures in lime and cement-treated subgrades containing sulfates led to questioning the validity of calcium based stabilization. When expansive soils containing sulfates are treated with calcium-based stabilizers, the calcium from the stabilizer reacts with soil sulfates and alumina to form the expansive mineral Ettringite.A series of resonant column (RC) tests (ASTM D 4015-92) was conducted on several chemically stabilized specimens of high-plasticity, sulfate-rich expansive clay from Sherman, Texas. Test results were used to assess the influence of mellowing period on the stiffness properties of stabilized soil. Specimens were tested for different stabilizer, mellowing periods, curing times, and confining pressures, and elapsed times under constant confinement. Two stabilizers, 6% lime and 4% lime + 8% fly ash were used. Soil stiffness parameters investigated include low-strain shear modulus (G), low-strain material damping ratio (D). Tests were also conducted at mid-to high-strain levels to study degradation effects of torsional shearing. 4% lime + 8% fly ash treatment method shows the best results.