Soil Stabilization White Paper

Here is a summary of a white paper by S.M. Rao and T. Thyagarj on Lime Slurry Stabilization of an Expansive Soil.

This paper investigates the effectiveness of lime slurry permeation for in-situ chemical stabilization of expansive soils. The study specifically focuses on the impact of lime slurry migration through artificially desiccated expansive soil specimens for use in soil engineering. Here are the key points and implications of the paper regarding mud jacking with a limestone slurry:

1. Objective and Background:
   • The study aims to evaluate lime slurry as a viable option for stabilizing expansive soils.
   • Expansive soils experience significant volume changes during wet and dry seasons, making them unsuitable for construction.
   • Lime stabilization involves both rapid physico-chemical reactions and long-term soil-lime pozzolanic reactions.
2. Laboratory Experiment:
   • Artificial desiccation of the expansive soil was done to induce shrinkage cracks, facilitating the migration of lime slurry.
   • Lime slurry was introduced through a central hole in the compacted soil, taking advantage of the shrinkage cracks for efficient permeation.
3. Results and Findings:
   • Lime slurry migration through desiccated soil promoted strong lime modification and pozzolanic reactions.
   • The treated soil exhibited reduced plasticity, decreased swell magnitude, and increased unconfined compressive strength.
   • Physico-chemical properties, such as pH, pore water salinity, and exchangeable calcium ion concentration, were significantly altered, indicating the effectiveness of lime slurry treatment.
4. Implications for Mud Jacking:
   • The paper suggests that slurry application to soil deposits with shrinkage cracks is effective for chemical stabilization.
   • Lime slurry can be preferable during the dry season, as the occurrence of shrinkage cracks facilitates lime migration.
   • Lime slurry injection is considered a viable choice for in-situ stabilization of expansive soil deposits, especially when soft soil deposits are unsaturated due to arid climatic conditions.
5. Practical Considerations:
   • The study recommends adopting the spacing recommended for lime piles for lime slurry applications, spreading them at 1–2 m centers.
   • Borehole depths for lime slurry application should extend below the depth of seasonal moisture content fluctuations or to depths where the load applied by the structure becomes insignificant.
6. Cost Implications:
   • The paper provides a brief illustration of costs for lime slurry application, suggesting that the method can be cost-effective.
7. Conclusion:
   • The experimental results indicate that lime slurry application is effective in chemically stabilizing expansive soils, rendering them less plastic and increasing their strength.
   • The paper emphasizes the importance of lime slurry application during the dry season and provides practical considerations for its implementation.

In summary, this study supports the use of lime slurry for mud jacking in expansive soils, especially during dry seasons when soil desiccation enhances the efficiency of lime migration and chemical reactions. The findings provide valuable insights for geotechnical engineers and practitioners involved in soil stabilization projects.