LIME STABILISATION - METHOD & BENEFITS

 Lime Stabilisation

Lime stabilisation is done by adding lime to the soil.It is very useful for stabilisation of clayey soils.When lime reacts with soil, there is exchange of cations in the adsorbed water layer and a decrease in plasticity of the soil occurs.The resulting material is more friable than the original clay and is therefore, more suitable as subgrade.Lime stabilisation improve the density and bearing capacity of the soil.Lime-soil stabilisation is useful to construct sub-base and base course for pavement.Lime treated soil is more suitable for warm regions where temperature is very high and for colder regions it is not suitable.

Quick lime is more effective as stabiliser than the hydrated lime, but the latter is more safe and convenient to handle.Generally the hydrated lime is used.It is known as slaked lime.Lime stabilisation is not effective for sandy soils because these soils can be stabilised in combination with clay, fly-ash or other pozzolanic materials.The ratio of fly ash to lime varies between 3 to 5.The fly ash is used about 10 - 20 % of the soil weight.

Method Of Mixing Lime Into Soil

The method of mixing lime into soils for stabilisation involves following steps:

• The soil which need stabilisation is scarified and pulverized by suitable equipment.

• Now add some amount of lime to the pulverized soil either the powder or slurry form and then mixed with suitable equipment.

• If lime powder is used then water is sprayed all over the soil.

• After spraying the water leave this mixture for 1 to 4 days. Lime-soil reaction is slow process and it required some time.

• Once the lime-soil reaction take place then spread the soil to required grade and compact it with rollers.

• When compaction is completed and the soil achieve the required dry density, the compacted lime-soil layer is allowed for curing for 1 week. 

• Finally after 1 week of curing the field tests are conducted to check water content and maximum dry density of compacted soil.

Factor Affecting Lime Soil Stabilisation

The following are the factors which affecting lime-soil stabilisation:

1. Soil Type
2. Lime Type
3. Lime Content
4. Compaction
5. Additives
6. Curing 

Benefits Of Lime Soil Stabilisation

• It is easy to mix with soil.
• It reduces the plastic properties of the soil when wetted.
• It sets slowly, the time interval between mixing and compacting is not critical.
• Cost of stabilisation is reasonably low.