Last edited 27 Nov 2019

BALLAST

BALLAST & TYPES OF BALLAST

Ballast:

Ballast is material like broken stone, gravel or any other granular material spread and packed below and around sleeper.

It provides good drainage for the track structure, It provides weed of greed, It holds sleepers in correct position by preventing movements caused by lateral load therefore ballast is used in the railway track.

Types of ballast is as follows:-

i) Broken stone

ii) Kankar

iii) Gravel

iv) Moorum

v) Brick ballast

vi) Blast furnaces slag

vii) Sand

viii) Ashes/cinders

ix) Selected earth

Broken sand:-

These are obtained from hard stones and it should be strong, hard, tough, durable, angular and does not flake when broken and hence Indian Railway adopt it very frequently.

Advantages:-

  • They are strong, durable and provide maximum stability to track.
  • These are mostly used for high speed track in India.
  • These types of ballast are cheaper in long run.

Disadvantages:-

  • The main disadvantages of this type of ballast is that its initial cost is more.

Moorum:-

It is normally used as an initial ballast in new construction. It is of red or sometimes yellow in color. It is Suitable for station yards.

Advantages:-

Disadvantages:-

  • It may turns into powder under heavy loads.
  • It may produces dusty track.
  • Maintenance of track with this type of ballast laid is difficult.

Sand:-

Coarse sand is generally used as ballast and is a moderate material to use as ballast.

Advantages:-

  • It is cheap material
  • It is easily available
  • It has good drainage property
  • It produces less noisy track.
  • It will not allow vegetation to grow on track
  • It is used on temporary and unimportant track.

Disadvantages:-

Kankar:-

Kankar are also used as ballast where other chief material for ballast is not easily available.

Advantages:-

Disadvantages:-

  • It is soft and hence it may convert into powder under heavy load.
  • It may have corrosive action on rails
  • Maintenance of track is difficult

Brick ballast:

It is generally in form of broken over burnt brick

Advantages:-

Disadvantages:-

  • It may have adverse effects on rails and metal sleepers as it may corrugate them
  • Maintenance of track laid with this material as ballast is difficult
  • It may produce dusty track as it turns into powder under heavy load

Ashes:

These are residue obtained from coal. It is also used as ballast.

Advantages:-

Disadvantages:-

  • It has got corrosive property and hence affect the rails and metal sleepers
  • It may laid track dusty as it gets easily reduced to powder under heavy load

Gravel:-

It is one of the best material used as ballast next to broken stone consisting of smooth round shaped material obtained from riverbed.

Advantages:-

Disadvantages:-

  • Due to rounded shape, it can easily rolls down due to vibrations and results in loosening of sleepers
  • Washing is required if gravels are obtained from pits
  • Screening is required as there is variation in size and quality
  • In short, uniform grading of gravel is required

Blast furnaces slag:

A byproduct obtained from manufacture of iron can also be used as ballast.

Advantages:-

  • It is cheap
  • It has good drainage property
  • It is strong and holds track in correct gauge and alignment

Disadvantages:-

Selected earth:

These are indurate clay and decomposed rocks. These are used as ballast when tracks to be laid on new formation. After consolidation, the surface becomes hard then good type of ballast is laid.

Advantages:-

  • It prevents loss of good ballast on new formation
  • It may be used on sidings and tracks.

<Humayoon Sial>

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