Laboratory Investigations of In Situ Stabilization of an Expansive Soil by Lime Precipitation Technique

The present investigation examines the efficiency of an in situ lime precipitation technique in stabilizing expansive soil through laboratory-scale model tests. Expansive soil was compacted in a cylindrical mold and sequentially permeated with CaCl2 and NaOH solutions into the expansive soil through a central hole filled with coarse sand. Successive permeation of CaCl2 and NaOH solutions into the compacted expansive soil resulted in precipitation of lime in the expansive soil mass. The precipitated lime reduced the plasticity index, controlled the swell-shrink potentials, and increased the unconfined compressive strength of the expansive soil by both strong lime modification reactions and soil-lime pozzolanic reactions. The results are corroborated with microfabric studies on lime precipitation treated specimens, which showed the formation of cementation bonds.