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 CaCl<inf>2</inf> and NaOH solutions into the expansive soil through a central hole filled with coarse sand. Successive permeation of CaCl<inf>2</inf> 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. © 2014 American Society of Civil Engineers.

T. Thyagaraj

Department Of Civil Engineering

Compressive strength

Lime

Shrinkage

Soil mechanics

Soils

stability

swelling

COMPACTED EXPANSIVE SOIL

Expansive soils

Geomaterials

Laboratory investigations

MODIFICATION REACTIONS

POZZOLANIC REACTION

Soil stabilization

Unconfined compressive strength

Stabilization

Expansive soil

Plasticity

PRECIPITATION (CHEMISTRY)

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

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

Journal of Materials in Civil Engineering

Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the independent contributions of either calcium chloride solution or sodium hydroxide solution in stabilizing the expansive soil are not known. Therefore, an attempt is made in the present investigation to examine the relative efficiencies of calcium chloride solution, sodium hydroxide solution and lime precipitation in stabilizing the expansive soil by comparing the physico-chemical and index properties, oedometer swell potentials and unconfined compressive strength of treated specimens. The present investigation also brings out the relative efficiencies of hydrated lime and precipitated lime in stabilizing the expansive soil. The experimental results showed that treating the expansive soils with calcium chloride and sodium hydroxide solutions independently promoted only the short-term reactions whereas the sequentially treating the expansive soil with calcium chloride and sodium hydroxide solutions resulted in the formation of lime precipitation, which could mobilize both short-term lime-modification reactions and long-term soil-lime pozzolanic reactions. © 2016 Taylor & Francis.

International Journal of Geotechnical Engineering

Relative efficiencies of electrolytes in stabilization of an expansive soil

Previous investigation showed that sequential mixing of calcium chloride and sodium hydroxide solutions with an expansive soil resulted in lime precipitation in the soil mass, which controlled the swelling potentials and increased the unconfined compressive strength of treated specimens through strong modification and pozzolanic reactions. However, expansive soils in the field are subjected to cyclic wetting and drying due to environmental conditions, which affects the swell-shrink behaviour. Therefore, the present investigation examines the efficacy of the lime precipitation technique in controlling the swell-shrink potentials and strength characteristics of expansive soils subjected to cyclic wetting and drying. Expansive soil is mixed sequentially with different concentrations of calcium chloride and sodium hydroxide solutions to yield a range of lime precipitation contents, and cured for different time periods. The cured specimens were subjected to cyclic wetting and drying in modified odeometer cells, and the swell-shrink potentials were monitored. The unconfined compressive strength of cured specimens was also determined after different cycles of wetting and drying in a sand bath. The laboratory results showed that the second swell potential was the maximum for untreated and lime precipitation treated specimens, in comparison with other wetting cycles. The equilibrium state was reached after about four to five cycles of wetting and drying. The equilibrium bandwidth reduced as the percentage lime precipitation and curing period increased. The unconfined compressive strength reduced with wetting and drying cycles, which indicated the loss of cementation after one wetting and drying cycle. © 2014, Thomas Telford Services Ltd. All rights reserved.

Proceedings of the Institution of Civil Engineers: Ground Improvement

Swell-shrink behaviour of lime precipitation treated soil

Lime stabilization prevails to be the most widely adopted in situ stabilization method for controlling the swell-shrink potentials of expansive soils despite construction difficulties and its ineffectiveness in certain conditions. In addition to the in situ stabilization methods presently practiced, it is theoretically possible to facilitate in situ precipitation of lime in soil by successive permeation of calcium chloride (CaCl2) and sodium hydroxide (NaOH) solutions into the expansive soil. In this laboratory investigation, an attempt is made to study the precipitation of lime in soil by successive mixing of CaCl2 and NaOH solutions with the expansive soil in two different sequences. Experimental results indicated that in situ precipitation of lime in soil by sequential mixing of CaCl2 and NaOH solutions with expansive soil developed strong lime-modification and soil-lime pozzolanic reactions. The lime-modification reactions together with the poorly developed cementation products controlled the swelling potential, reduced the plasticity index, and increased the unconfined compressive strength of the expansive clay cured for 24 h. Comparatively, both lime-modification reactions and well-developed crystalline cementation products (formed by lime-soil pozzolanic reactions) contributed to the marked increase in the unconfined compressive strength of the expansive soil that was cured for 7-21 days. Results also show that the sequential mixing of expansive soil with CaCl2 solution followed by NaOH solution is more effective than mixing expansive soil with NaOH solution followed by CaCl2 solution. © 2012 American Society of Civil Engineers.

Laboratory studies on stabilization of an expansive soil by lime precipitation technique

Reviewers

2012 International Joint Conference on Service Sciences

Amelioration of Expansive Clay Slopes Using Calcium Chloride

Laboratory investigations of in situ stabilization of an expansive soil by lime precipitation technique

Journal	Data powered by TypesetJournal of Materials in Civil Engineering
Publisher	Data powered by TypesetAmerican Society of Civil Engineers (ASCE)
ISSN	08991561
Open Access	No