Matric Suction, Volume Change, and Microstructural Characteristics of a Highly Expansive Soil Treated with Lime

This study examines the impact of lime treatment on matric suction, swelling, and shrinkage response of a highly expansive soil, both at the macro- and micro-scales. The macro-scale investigations include the determination of compaction, compressibility, swelling pressure, DFSI, volumetric shrinkage, and matric suction response of lime-treated expansive soil (0–6% of lime content). The alterations in the pore size and fabric of the soil at micro-scale were assessed using scanning electron microscopy and Brunauer–Emmett–Teller gas adsorption technique. An increase in intra-aggregate pores followed by the reduction in inter-aggregate pores was evident from the microscopic observations. These micro-fabric changes led to an increase in matric suction within the compacted lime-treated specimens. In macro-level investigations, an amount of lime higher than the lime fixation point was found to be efficient to control the volumetric changes in the expansive soil. Addition of 6% lime reduced the compressibility and volumetric shrinkage of expansive soil by 86% and 84%, respectively. The rate of primary shrinkage of expansive soil was also observed to be reduced with lime addition owing to an increase in the water retention capacity. The swelling response of this highly expansive soil was completely nullified with only 4% lime, whereas shrinkage could not be fully controlled even for higher lime content of 6%.