Lime Stabilization of Soil: A Physico-Chemical and Micro-Mechanistic Perspective
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ORIGINAL PAPER
Lime Stabilization of Soil: A Physico-Chemical and MicroMechanistic Perspective Arvind Kumar Jha1,3 • P. V. Sivapullaiah2,3
Received: 20 September 2018 / Accepted: 17 May 2019 Ó Indian Geotechnical Society 2019
Abstract Lime stabilization is a well-established technique to improve the subgrade properties of different soil for pavement construction, despite construction difficulties and its ineffectiveness in certain conditions. However, a greater level of understanding is needed to know the mechanism of alteration in the properties of soils, particularly to longevity potential of ionic interaction. In the present study, mechanism of long-term strength behaviour of lime-treated soil has been brought clearly through alteration in ionic exchange (Ca2?, Mg2?, Na? and K?), mineralogy and microstructure by performing series of physico-chemical and micro-analyses (XRD, SEM and EDAX). The results revealed that addition of lime to soil influences greatly the concentration of sodium (Na?) and calcium (Ca2?) ions with marginal alteration in potassium (K?) and magnesium (Mg2?) with curing periods. The variation in concentration of Ca2? with curing periods has attributed to the strong cation exchange reactions at early stage and consumption of calcium in the formation of cementitious compounds with an increase in curing periods. However, concentration of Ca2? increases after curing for longer periods, indicating the increase in solubility of cementitious compounds. Alterations in mineralogy and microstructure with an increase in curing periods of limetreated soil substantiate the effect of changes in ionic
& Arvind Kumar Jha [email protected] P. V. Sivapullaiah [email protected] 1
Manipal University Jaipur, Jaipur, India
2
GITAM University Bangalore, Bangalore, India
3
Indian Institute of Science, Bangalore, India
concentration. Further, a significant increase in the strength up to 28 days and marginal up to 1 year substantiates that variation in Ca2? and thereby, formation of cementitious compounds control the strength behaviour of lime-treated soil. Keywords Ions exchange Lime pH Pozzolanic Strength
Introduction Behaviour of fine-grained soils is controlled by various factors such as changes in stress system, moisture variation and chemistry of pore fluid [1]. Lime treatment to improve the soil properties of fine-grained soil is practiced since the previous several decades. It is reported by Freeboroug [2] and Thompson [3] that the lime is, firstly, applied in the construction of highway and airfield pavements with compaction of the soil–lime mixtures. It is also mentioned in Silpa Sastra (1500 A. D.) that among several methods, an addition of hydraulic lime was one of the approved methods of the soil stabilization in ancient India [4]. However, various forms of lime either in quick lime (CaO) or in hydrated lime [Ca(OH)2] are used effectively to improve the physical and engineering properties of soils for different construction projects [5]. The whole improvement in the properties of
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