Stabilization of soil

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CHEMICAL STABILIZATION

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TYPES OF STABILIZATIONS
 Mechanical Stabilization
 Geosynthetic Stabilization
 Electrical & Heat Stabilization
 Chemical Stabilization
i) Lime Stabilization
ii) Cement Stabilization
iii) Bitumen Stabilization
iv) Fly ash Stabilization
v) Other chemicals

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Chemical Stabilization
 Transformation of the soil index properties by
adding chemicals thereby improving
a) volume stability
b) strength & stress-strain properties
c) permeability and durability
 Mechanisms of alteration

4. 4
Selection of method of stabilization

5. Lime Stabilization
 Involves the use of burned lime products,
quicklime, hydrated lime (oxides & hydroxides)
or lime by-products to the soil for stabilizing it.
 It has been applied to all types of roads,
temporary construction roads, parking lots,
railroad beds, irrigation canals, earth dams etc.
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6. Mechanism
• Lime is a strong alkaline base.
• Reacts chemically with clays causing a base exchange.
• Calcium ions displace sodium and hydrogen cations and
combine with available silica & alumina in the soil to form
complex silicates & aluminates which are cementing
materials.
• Rapid change in plasticity due to a strong reaction between
OH- from the lime & H+ from within the clay mineral
structure to form water.
• Results in an immediate reduction in the plastic limit of soil.
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7. • Other changes include reduction in volume change
characteristics of the soil, flocculation of clay
particles, increase in OMC, thereby permitting
compaction under wetted conditions.
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8. Determination of amount of lime to be used must be
based on laboratory testing such as paticle size
gradation, plasticity index, strength tests etc.
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9. Objectives
 Improve wokability
 Increase strength
 Increase the strength of subgrade soils over
long term
 Increase durability
 To increase the bearing capacity & to reduce
the settlements
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10. 10
Construction Procedure
Standard stabilization includes:
 Scarifying
 Lime spreading
 Mixing and pulverizing
 Compaction
 Shaping of stabilized base
 Curing
 Testing

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Monitoring
Field Tests are conducted
 Penetration resistance
 Unit weight
 Permeability
 Subgrade Reaction

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 Laboratory Tests
Shear strength
Permeability
Unit weight
Compressive strength

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Applications:
 Plastic clayey soils
 Clay-gravels
 Gravels with high fine content
 Fine grained soils ranging from clays to silty
clays.

14. Environmental concerns
 Lime dust, easily blown by wind, when highly
inhaled by people is hazardous and can pollute
streams nearby.
 Prolonged contact of lime may cause bad burns.
 Quicklime can produce severe burns when in
contact with moist skin.
 Lime burns in eyes may result in loss of sight.
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15. Safety Precautions
 Clothing
 Protective cream
 Eye protection
 Mouth/Nose protection
 After work
 First aid
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16. Lime Columns
 A mixing tool is penetrated to the desired depth
after which during retreival a lime mixture is
injected into the soft soilusing compressed air,
then mixed with soil.
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18. Uses
 As foundation for light buildings
 Alternative to piles & floating foundation
 Function as drains in the soils
 Stabilize trenches and deep excavations
 Improve stability of slopes
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