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Wilma Caldwell
Architectural technologist
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What are the type of Soil Stabilization of Highway Embankment?

What are the type of Soil Stabilization of Highway Embankment?

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Soil stabilization is the process of improving the shear strength parameters of soil and thus increasing its bearing capacity in road construction. 

It is required when the soil available for construction is not suitable to carry structural load. Generally, soils exhibit undesirable engineering properties unless they are treated to enhance their physical properties. 

Stabilization can increase the shear strength of a soil and control its shrink-swell properties, thereby improving the load bearing capacity of a sub-grade to support pavement and its foundation19

Soil stabilization is used to reduce permeability and compressibility of the soil mass in earth structures and to increase its shear strength. 

There are four types of stabilization

  1. Mechanical
  2. Chemicals
  3. Biological
  4. Using polymers

Mechanical:

This includes compacting the soil to physically change the properties of the soil. The compaction can be either vibrating or dynamic.

Another way to mechanically stabilize the soil is to remove excess water from the soil.

Chemical:

The soil is stabilized by adding chemicals to the soil. The chemicals include cement, fly ash, lime, GGBS, bitumen, and pozzolana

Biological:

Planting trees will reduce erosion in highways close to rivers and canals. Trees will hold the soil particles together creating optimal soil porosity and retaining water.

Using Polymers:

These include using geopolymers, textiles, and other synthetically woven materials that have high strength.

Terry Collins
Sustainability consultant

There are two main type

Mechanical method Chemical method

Mechanical method

This includes compacting the soil, for physical change the properties of the soil.

Another way to mechanically stabilize the soil is to remove excess water from the soil; hence soil consolidation occurs.

Chemical method

The soil is stabilized by adding chemicals to the soil. The various chemicals is cement, fly ash, lime, GGBS, bitumen, and pozzolana

Dennis Holt
Entry level engineer

There are three broad types of soil stabilization, they are;

1. Biological soil stabilization :- This is achieved through afforestation or planting and its main purpose is erosion control. Root traits such as architectural, morphology, physiological and biotic play an important role in both the physical and chemical development of soils enabling structural stability of soil.

2. Physical stabilization :- It is the modification of soil particle size distribution and plasticity by the addition or subtraction of different soil fractions in order to modify its physical properties.

3. Chemical types of soil stabilization :- It can be achieved through use of traditional and non-traditional agents.

An embankment refers to a volume of earthen material that is placed and compacted for the purpose of raising the grade of a roadway (or railway) above the level of the existing surrounding ground surface. Highway embankments made of heavy materials are often built over soft ground and this can sometimes leads to settlement and instability of the embankment.

Soil stabilization of highway embankment

Soil Stabilization
• Mechanical stabilization: Improvement of soil properties can be achieved by changing particle gradation. The engineering performance depends
mainly on grain size distribution and plasticity.
Significant changes in the properties can be made by the addition or removal of suitable soil fractions.
Granular fraction imparts strength and hardness. Fine fraction imparts cohesion, water, retention capacity and it acts as filler.
• Extreme caution is required for adding fine to roadbases and subgrades.
• The common technique of soil alteration is the addition of sodium montmorillonite (bentonite) to reduce the permeability of the soil. Addition of 10% of 

What are the type of Soil Stabilization of Highway Embankment?

bentonite reduces permeability coefficient k. Asphalt
have been also tried.

Lime Stabilization :
Hydrated (or slacked) lime is very effective in
treating heavy plastic clayey soils. Lime may be used alone or in combination with cement, bitumen, or flash. Lime has been mainly used for stabilizing the
road bases and subgrades.
• On addition of lime to the soil, two main types of
chemical reactions occur i) alteration in the nature of the adsorbed layer through base exchange phenomenon and ii) cementing or pozzolanic action.
Lime reduces P.I. of highly plastic soils making them more friable and easy to be handled and pulverized.
The P.I. of low plasticity generally increases. There is generally an increase in the O.M.C. and decrease in the compacted density, by strength and durability
increases.
• Normally 2 10 8 % of lime may be required for coarse-grained soils and 5 to IO % for plastic soil.

What are the type of Soil Stabilization of Highway Embankment?

Cement Stabilization :
The soil stabilized with cement (Portland) is known as soil cement. The cementing action is believed to be the result of chemical reactions of cement with silicious soil during hydration. The binding action of individual
particles through cement may be possible only in coarse-grained soils. In cohesive soils, only some of the particles can be excepted to have cement bonds and the rest will be bonded through natural cohesion.

What are the type of Soil Stabilization of Highway Embankment?

Bitumen Stabilization :
• Earth roads can be improved by spraying the dry soil surface with a stabilizer such as aspheric and cut back bitumen oil, tars, or emulsions in small quantities. The bituminous materials when added to soil impact cohesion or binding action and reduce water absorption. About 4 to 7 % by weight of
bitumen is required. Any inorganic soil can be
stabilized well-graded soils give goods results from 10^3 mm/s to 10^8 mm/s in case of silty sands. Local clays may be used.

What are the type of Soil Stabilization of Highway Embankment?

These are the methods of stabilization