Transcript Soil Stabilization

Soil Stabilization
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The soil stabilization means the improvement of
stability
or bearing power of the soil by the use of controlled
compaction, proportioning and/or the addition of suitable
admixture or stabilizers.
Basic Principles of Soil Stabilization….
• Evaluating the properties of given soil
• Deciding the lacking property of soil and choose
effective and economical method of soil stabilization
• Designing the Stabilized soil mix for intended stability
durability values
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and
Need for Soil Stabilization
 Limited Financial Resources to Provide a
complete network Road System to build in
conventional method
 Effective utilization of locally available soils
and other suitable stabilizing agents.
 Encouraging the use of Industrial Wastages
in building low cost construction of roads.
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Methods of Soil Stabilization
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Mechanical Stabilization
Soil Cement Stabilization
Soil Lime Stabilization
Soil Bitumen Stabilization
Lime Fly ash Stabilization
Lime Fly ash Bound Macadam.
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Mechanical Stabilization
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This method is suitable for low volume roads i.e.
Village roads in low rainfall areas.
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This method involves the correctly proportioning of
aggregates and soil, adequately compacted to get
mechanically stable layer
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The Basic Principles of Mechanical Stabilization are
Correct Proportioning and Effective Compaction
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Factors Affecting Mechanical
Stabilization
• Mechanical Strength of aggregates
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Gradation
Properties of the Soil
Presence of Salts
Compaction
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Mechanical Strength
• When the soil is used in small proportion to fill up
the voids the crushing strength of aggregates is
important
Gradation
• A well graded aggregate soil mix results in a mix with
high dry density and stability values
Properties of soil
• A mix with Plasticity Index, results poor stability
under soaking conditions. Hence it is desirable to limit
the plasticity index of the soil
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Presence of Chemicals
• Presence of Salts like Sulphates and mica
are undesirable
• Presence of Calcium Chloride is Beneficial
Compaction
• Effective Compaction is desirable to
produce high density and stability mix
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Soil Cement Stabilization
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Soil Cement is an intimate mix of soil, cement
and water, compacted to form a strong base
course
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Cement treated or cement modified soil refers
to the compacted mix when cement is used in
small proportions to impart some strength
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Soil Cement can be used as a sub-base or base
course for all types of Pavements
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Factors affecting soil cement stabilization
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Soil
Cement
Pulverisation and Mixing
Compaction
Curing
Additives
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Soil
THE PHYSICAL PROPERTIES
• Particle Size Distribution
• Clay content
• Specific Surface
• Liquid limit and Plasticity Index
Cement
A increase in cement content generally causes
increase in strength and durability
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Pulverisation and Mixing
• Better the Pulverisation and degree of mixing, higher
is the strength
• Presence of un pulverised dry lumps reduces the
strength
Compaction
• By increasing the amount of compaction dry density
of the mix, strength and durability also increases
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Curing
Adequate Moisture content is to be retained in
order to accelerate the strength
Additives
There are some additives to improve properties
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Lime
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Sodium hydroxide
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Sodium Carbonate
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Calcium Chloride
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Soil Lime Stabilization
• Soil- Lime has been widely used as a
modifier or a binder
• Soil-Lime is used as modifier in high plasticity
soils
• Soil Lime also imparts some binding action
even in granular soils
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Soil-Lime is effectively used in Expansive
soils with high plasticity index.
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Factors affecting Properties of Soil-Lime
Lime Content
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Generally increase in lime content causes slight
change in liquid limit and considerable increase in
Plasticity index
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The rate of increase is first rapid and then
decreases beyond a certain limit
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The point is often termed as lime fixation point
This is considered as design lime content
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Type of Lime
 After long curing periods all types of limes produce
same effects. However quick lime has been found
more effective than hydrated lime
 Calcium Carbonate must be heated at higher
temperature to form Quick lime calcium oxide(
CaO)
 Calcium oxide must be slaked ( by the addition of
water) to form Hydrated lime
Compaction
 Compaction is done at OMC and maximum dry
density.
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Curing
• The strength of soil-lime increases with curing
period upto several years. The rate of increase is
rapid during initial period
• The humidity of the surroundings also affects the
strength
Additives
• Sodium metasilicate, Sodium hydroxide and
Sodium Sulphate are also found useful additives
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Soil- Bituminous Stabilization
• The Basic Principles of this stabilization are Water
Proofing and Binding
• By Water Proofing inherent strength and other
properties could be retained
• Most Commonly used materials are Cutback and
Emulsion
• Bitumen Stabilized layer may be used as
Sub-base or base course for all the roads
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Factors affecting properties of soil-bitumen
Soil
• The particle size, shape and gradation of the soil
influence the properties of the soil-bitumen mix.
Types of Bitumen
• Cutbacks of higher grade should be preferred
• Emulsions generally gives slightly inferior results
than Cutback.
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Amount of Mixing
• Increasing proportion of bitumen causes a decrease
in dry density but increases the stability after a
certain bitumen content
• The optimum bitumen content for maximum
stability generally ranges from 4 to 6%
Mixing
• Improved type of mixing with low mixing period
may be preferred
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Compaction
• Effective Compaction results higher
stability and resistance to absorb water
Additives
• Anti stripping and reactive chemical
additives have been tried to improve the
properties of the mixes
• Portland cement can also be used along with
the soil bitumen
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The End
…..Thank you…….
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