Lime pile techniques for the improvement of clay soils

Abstract

Soil improvement is one of the basic requirements for preparing in situ soils for appropriate strengthening, stiffness, and stability in civil engineering designs and applications. The modification technique, which involves mechanical, thermal, and chemical components, requires monitoring techniques to determine its efficiency and suitability. This study examines the geotechnical improvement of clay soils using the lime pile technique on a laboratory-scale model. The clay–lime physicochemical reactions resulting from cation exchange were examined through basic experimental analyses. In addition, electrical conductivity measurements were performed on the selected treated soils to examine variations in their electrical properties. Remolded compacted clay soil blocks were carefully prepared in circular steel test tanks with lime piles installed in them. The treated soil block properties were then investigated as a function of radial lime pile distances and curing periods. It was observed that there are significant changes in the Atterberg limit, linear shrinkage, compaction characteristics, and strength of the treated soils due to the clay–lime reactions. The results indicate that these reactions have remarkable effects on the electrical properties of the lime pile–treated soil and produced strong interparticle bonds and unconfined compressive strength of the soil. This is attributed to the migration of Ca2+ and Mg2+ ions from the lime piles into the soil, flocculation of particles, and pozzolanic reactions. The significant changes in the electrical properties and shear strength values suggest that their correlative changes can be used as a monitoring technique to determine the improvement in geotechnical properties of chemically treated soils.