Lime Stabilization

 

LIME STABILIZATION

 

INTRODUCTION:  Lime has been used as a soil stabilizer for roads from olden days

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Lime is produced from natural limestone .

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The type of lime depends upon the parent rock and production process.

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TYPES OF LIME 

The types of lime formed is based upon the parent material and production process. There are

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5 basic types of lime :

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1. High calcium quicklime - CaO 2 Dolomite quicklime - CaO+MgO

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3. HYDRA HYDRATED TED HIGH CALCIUM LIME

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4. Normal Normal hydrated dolomite lime

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5.Pressure hydrated dolomite lime -Ca(OH)2+Mg(OH)2 -Ca(OH)2+Mg(OH)2

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-Ca(OH)2

-Ca(OH)2+MgO

 

HYDRATED LIME: Hydrated lime is the most commonly used one for soil stabilization. stabilization. •

Lime is also used in combination with other admixtures like fly ash,cement, bitumen etc. •

HYDRATED LIME

 

ENGG PROPERTIES 

Lime stabilization creates a number of important engineering properties in soils:

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Improved strength

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Improved resistance to fracture, fatigue, and permanent deformation

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Improved resilient properties;

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Reduced swelling

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Resistance to the damaging effects of moisture.

 

REACTIONS 

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Two types of chemical reaction take place when lime is added to wet soil The first one is a colloidal type involving any of the reactions: 1. of calcium for the ion naturally carried by Ion the exchange soil. 2.a depression of the double layer on the soil colloids because of the increase in cation concentration of the pore water 3..an expansion from the high ph of of the the double lime layer of the soil colloids The second one takes considerable time in a cementing action involves the reaction between the calcium from the lime with the available reactive alumina or silica from the soil.

 

BENEFITS 

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Soil plasticity , density and strength are changed by the addition of lime to soil. Plasticity reduction Reduction in moisture-holding capacity Lime generally increases the plasticity index of low plasticity soils and decreases the plasticity index of highly plastic soils. Because of the reduction in plasticity of the plastic soil, due to addition of lime ,the soil becomes more friable and easy for handling in the field. Addition of lime causes a reduction in the maximum compacted density and an increase in the optimum moulding water content. In general lime increases the strength of almost all types of soil.

 

CONSTRUCTION PROCEDURES 

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Construction procedure of lime-stabilized soil bases are similar to those employed for soil cement with the difference that more time is allotted for placement operation for lime. This takes place since the lime-soil cementation reaction is very slow . Adequate care should be taken to avoid carbonation of lime. lime. NORMAL CONSTRUCTION SEQUENCE IS GIVEN BELOW: 1. Scarify the cement 2.Pulverise the soil 3.Spread the soil 4.Mix the lime and soil

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5.Add waterthe if necessary op timum moisture content 6.Compact mixture to bring to optimum 7.Shape the stabilized base 8.Cure-keep moist and traffictraffic-free free for atleast 5 days. 9.Add wearing surface.

 

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