In forming railway ballast, there are numerous materials that are commonly used:
- Broken stone
- Cinders and/or ashes
- Selected Earth
Below are how each of these materials are used in railway ballast, as well as the benefits and disadvantages of using each one.
Broken stone is one of the most popular materials for railway ballast, as nearly all important railway tracks are provided with this material. The stone used should be hard, tough, nonporous and should not decompose when it is exposed to air and/or light. Of all the types of stone available, igneous rocks like quartzite and granite are considered among the very best when choosing ballast materials. In the event that these igneous rocks are not available, limestone and sandstone are common and effective alternatives.
- It holds the track in proper position.
- It is durable and can withstand heavy traffic.
- It also handles high speeds very well.
- The initial cost of broken stone railway ballast can be quite high.
Right beneath broken stone, gravel rates very highly as a material used in railway ballast. Many countries around the world use gravel for this purpose-and in very large quantities, as well. Worn fragments of rocks occurring in natural deposits are gathered to form gravel, and may be obtained from river beds.
- Because gravel does not have to be broken down, it is an inexpensive but effective alternative to broken stone ballast.
- As long as it remains properly cleaned, gravel railway ballast has outstanding drainage properties.
- Vibrations can cause gravel to roll down.
- Because pieces of gravel can vary so much in size, additional screening is usually required prior to its use.
- When obtained from gravel pits, gravel is full of earth and other organic matter, and requires proper cleaning if it is to be used as effective ballast.
Coarse sand is preferred over finer sand, and makes for excellent railway ballast. The best sand contains fine gravel carrying in size.
- If there is no earth or vegetation present in the sand, it forms a very efficient water drain-off.
- When sand is available locally, it is very inexpensive.
- Sand produces a very quiet track.
- When there are vibrations, sand can be easily disturbed. This makes maintenance fairly difficult.
- Sand can easily be washed off or blown away, meaning that it requires frequent renewal.
- If sand particles get into the moving parts of vehicles, it can produce friction-which leads to heavy wear of vehicles.
Cinders and/or Ashes
When locomotives and other furnaces use coal, this produces a residue called cinder (or ashes). This type of ballast material seems to only be a natural solution, as it is already produced as a byproduct of the railway.
- This material is very easily handled.
- It is very cost effective and can also be used for sidings.
- Especially for an inexpensive product, cinder/ashes is actually a very good drainage agent.
- It is easy to get hold of large quantities of cinder/ashes on short notice.
- In the event of an emergency such as the destruction of portions of railway tracks, this material is very useful and can be used in repairing and packing the track.
- Cinder/ashes is highly corrosive, and cannot been used with steel sleepers.
- This type of material effects the foot of the rails.
- It is very soft and can be shifted significantly under vibrations. This causes the track to become dusty, which is definitely not ideal in very dry weather.
This lime agglomerate is found very commonly, and is typically discovered in the form of nodules that exist in various sizes.
- Kankar makes for a good substitute when other materials for ballast are unavailable.
- This material functions ideally under light traffic.
- Because kankar is very soft, it can be reduced to powder form very easily. This makes the track very dusty, similarly to ashes/cinders.
- It can be very difficult to maintain kankar.
In newly-laid tracks and sidings, selected earth can be used as effective railway ballast.
The broken pieces of burnt bricks, called brickbats, are used as materials for ballast.
- Brick has excellent drainage properties.
- Brickbats may be used as ballast material where other suitable ballast materials are either unavailable or unaffordable.
- Brickbats turn into powder form easily, causing the track to become dusty.
- Maintenance of tracks laid with brick ballast is very difficult to accomplish.
When laterite decomposes, it forms moorum. This material is of red or yellow color, and the highest-quality moorum contains large amounts of small laterite stone.
- Moorum is a great alternative material used for ballast when other options are not available.
- It can be safely used on a newly laid track.
- Moorum possesses great drainage properties.
- Because moorum is very soft, it reduced to a powder and forms dust in a short period of time.
- Maintenance of tracks laid with moorum is very difficult.
If you need Railway Ballast for any construction work then consult with Aggregate Supplier, Lamarche McGuinty Inc.