What is soil compaction? , What is compaction? , Factor affecting compaction

 What is compaction ?

Compaction means pressing the soil particles close to each other by mechanical method. During the compaction air is expelled from the void space in the soil mass. Compaction is the process of increasing the bulk density of soil for aggregate by driving out air.

Soil compaction

1. Increasin density
2. Increases strength characteristics
3. Increase load bearing capacity
4. Increase effective stress
5. Increase negative pore pressure
6. Decrease undesirable settlement
7. Decrease permeability 
8. Decrease water seepage
9. Decrease frost damage
10. Decrease swelling and shrinkage
11. Decrease erosion damage

Factor affecting compaction:-

1. Water content:-

With increase in water content compacted density increase up to a stage beyond which compacted density decrease.

The maximum density achieved is called MDD and the corresponding water content is called OMC.

At lower water contents then OMC soil particles are held by the force that prevents the development of diffused double layer leading to low inter particles repulsion.

2. Effect of amount of compaction:-

Effect of increasing compactive effort is to increase MDD and reduced OMC.

There is no linear relationship between compactive effort and MDD.

3. Effect of method of compaction:- 

The density obtain during compaction for a given soil greatly depends upon the type of compaction or the manner in which the compactive effort is applied.

4. Types of soil:-

The maximum dry density achieved corresponding to a given compactive energy largely depends upon the type of soil.

5. Admixture:-

The compaction characteristics of the soil are improved by adding other materials known as admixture.

The most commonly used admixture or lime cement and bitumen.

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