Ballast is a layer of broken stone, gravel, or any other suitable material placed under and around the sleepers for distributing the load from the sleepers to the formation.
Functions of Ballast
- It provides a suitable foundation for the sleepers.
- It transfer and distributes loads from the sleepers to a larger area of formation.
- it provides effective drainage to the track.
- It helps in protecting the top surface of the formation.
Physical Properties of Good Ballast
- It should be hard and tough.
- It should water resistant and durable.
- It should be non-porous and non-absorbent of water.
- It should be cheaper and easily available.
- It should not be brittle.
- It should not allow rain water to accumulate
Types of Ballast
It is the best material to be used as ballast.
Generally on all important tracks broken stone Ballast has been used.
Blast of Igneous rocks is the most suitable
It stands second in suitability as ballast.
Used in large quantities in many countries.
It is obtained from river beds
3. Cinders or Ashes
The residue obtained from the coal used in locomotives is known as Cinder or Ash.
It stands fourth in merits as Ballast material.
Coarse sand is better than fine sand.
5. Brick ballast
Where stone or other suitable ballast is not available, over burnt brick ballast can be used.
It is found in the form of particles of varying sizes.
Where stone is not easily and at reasonable price available, kankar can be used as road metal and ballast for railway tracks.