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RAILWAYS

The document provides an overview of railway ballast, detailing its background, types, design, and specifications. Ballast is essential for supporting sleepers, distributing loads, and ensuring track stability and drainage. Various materials are used for ballast, including broken stone, sand, and gravel, each with specific requirements and properties.

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2023ugce014
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10 views10 pages

RAILWAYS

The document provides an overview of railway ballast, detailing its background, types, design, and specifications. Ballast is essential for supporting sleepers, distributing loads, and ensuring track stability and drainage. Various materials are used for ballast, including broken stone, sand, and gravel, each with specific requirements and properties.

Uploaded by

2023ugce014
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 10

Railway

Ballast
Menu
1. Background

2. Types

3. Ballast Design
4.Ballast Specification

05 Self Stabilizing Tracks

9/15/2022 2
Background
Ballast is the granular material, usually
broken stone or brick, shingle or
kankar, gravel or sand, packed
below and around the sleepers to
transmit load, and at the same time
allowing the drainage of track.

It provides suitable foundation for the


sleepers, hold them in correct position
and prevent their displacement by
lateral and longitudinal thrust.

9/15/2022 3
Background
Functions: Requirements:
 Provide level and hard bed for sleepers  Tough

 Hold sleepers in position  Hard enough

Transfer and distribute load to wide  Cubical, with sharp edges (angular)
area
 Resist attrition
 Provide elasticity or resilience to track

 Provide longitudinal and lateral stability  Durable https://www.google.com/url?sa=i&url=ht


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 Provide effective drainage


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 Good drainage https://www.google.com/url?sa


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 Maintain level and alignment of track


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 Cheap and economical


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9/15/2022 4
Types of ballast  Blast Furnace Slag, Cinders
 Used in yards, sidings etc.

 Broken stone  Used as initial ballast in new construction

 Mostly used on Indian Railways  Cheap and easily available


 Procured from hard stones like granite,  Corrosive, harmful for steel sleepers and
quartzite, etc. fittings

 Economical in long run


 Moorum
 Sand  Used as initial ballast in new constructions or
as sub-ballast.
 Mostly used for CI Pot sleepers
 In low density areas with wooden and  Also used as blanketing material on black

ST sleepers cotton soil.

 Coarse sand is preferred  Others


 Causes excessive wear on rail top and  Gravel, River Pebbles, Kankar, Brick Ballast,
moving parts of the rolling stock etc.
Ballast Design
 Minimum Depth of Ballast section =1/2[Sleeper Spacing – Width
of Sleeper]

 A minimum cushion of 15-20 cm of ballast below the sleepers is


prescribed on IR.

 In LWR, it is 25 cm. For routes with speed more than 130 kmph, it
is 20-30 cm with 15 cm of sub-ballast.
Ballast Specification
 Quality  Size and Gradation
 Hard, durable and angular  50 mm is the designated size

 Free from weathered and organic materials  Retained on 65 mm: nil, 5%max

 Should be cubical in shape  Retained on 40 mm: 40-60%

 Should be machine crushed  Retained on 20 mm: not less than 98%for machine
crushed and not less than 95%for hand broken.
 Physical Properties
 Abrasion: 30%Max (BG), 35%Max (MG, NG)  Compaction
 Impact Value: 20%Max (BG), 30%Max (MG,  Packing: Compacted ballast cushion laid below

NG) sleepers as per the gradation

 Boxing: Relatively Loose ballast placed on the side of


 Water Absorption: 1%Max
the sleepers to provide them lateral stability
 Flakiness and Elongation Index: Max
50% each
9/15/2022 7
https://pavementinteractive.org/reference-
desk/testing/aggregate-tests/los-angeles-abrasion/

https://theconstructor.org/building/building- https://www.engineeringcivil.co
material/determination-of-aggregate-impact-value/1355/ m/flakiness-index-test-for-
aggregates.html

https://www.engineeringcivil.com/elongation-
index-test-for-
aggregates.html#:~:text=TEST%20DESCRIPTIO
N,size%20larger%20than%206.3%20mm.

9/15/2022 8
Ballast Specification

 Screening
 Procedure of renewing the ballast section
 Crushed material has clogged the voids causing
drainage problem

 Ballast has penetrated into formation

 Ballast has been blown away

9/15/2022 9
THANK
YOU

9/15/2022 11

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