SPECIFICATIONS
FOR TRACK BALLAST
CONTENTS
SPECIFICATION FOR TRACK BALLAST
1
SCOPE: These specifications will be applicable for stone ballast
to be used for all types of sleepers on normal track, turnouts, tunnels and
deck slabs etc. on all routes.
2
DETAILED SPECIFICATIONS:
2.1 GENERAL.
2.1.1
Basic Quality: Ballast should be hard durable and as far as possible
angular along edges/comers, free from weathered portions of parent rock,
organic impurities and inorganic residues.
2.1.2
Particle Shape: Ballast should be cubical in shape as far as
possible. Individual pieces should not be flaky and should have generally flat
faces with not more than two rounded/sub rounded faces.
2.1.3 Mode
of Manufacture: To ensure
uniformity of supply machine crushed ballast should be preferred for broad
gauge and metre gauge routes, procurement of hand broken ballast shall be
resorted to only with the prior personal approval of CE/CTE in open line and
CAO/Con for construction projects who should record reasons while granting such
approval before calling of tender in each case for ballast supply on Broad
gauge and metre gauge routes. However, no such approval is needed for Narrow
Gauge routes and Metre Gauge sections (including yard lines), which have not
been planned/sanctioned for Broad Gauge conversion.
2.2
PHYSICAL PROPERTIES:
2.2.1 Ballast
sample should satisfy the following physical properties in accordance with IS:
2386 Pt IV - 1963 when tested as per the procedure given in Annexure 1 & 2.
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BG &
MG
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NG
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Aggregate Abrasion Value:
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30% Max.
*
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35% Max.
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-
Aggregate Impact Value:
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20% Max*
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30% Max.
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*Relaxable upto 35% & 25% respectively on techno economic grounds
by CTE/CE in open line and CAO/Con for construction projects. The relaxation
in Abrasion and Impact Value on Techno Economic grounds shall normally be given
prior to the issue of Tender notice/Tender document and not after the same. If
however due to some reasons these relaxations have to be given after the
opening offender but before acceptance, then the reasons/or same should he
recorded.
No approval for relaxation in the Abrasion and Impact Values by CTE/CE
if needed in case of supply of ballast for metre gauge sections (including yard
lines) which have not been planned sanctioned for broad gauge conversion.
2.2.2 The "Water
Absorption" tested as per IS:2386 Pt III - 1963 following the procedure
given in Annexure 3 should not be more than 1%. This test however, to be
prescribed at the discretion of CE/CTE in open line and CAO/Con for
construction projects.
2.3 SIZES
AND GRADATION:
2.3.1
Ballast should satisfy the following size and gradation:
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a)
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Retained on 65mm Sq. mesh
sieve
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5%Maximum.
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b)
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Retained on 40mm sq. mesh
sieve *
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40%-60%
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c)
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Retained on 20mm sq. mesh
sieve
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Not less than 98% for
machine crushed
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Not less than 95% for hand
broken.
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* For
machine crushed ballast only.
2.3.
Oversize Ballast:
i) Retention
on 65mm square mesh sieve.
A maximum of 5% ballast
retained on 65mm sieve shall be allowed and no deduction in payment shall be
made for this.
In case of hand broken
ballast all ballast shall be sieved through 65mm square mesh sieve before it is
allowed to be stacked and offered for measurement. In isolated stacks, upto 10%
ballast retained on 65mm sieve may be permitted but the average of various
samples taken at the time of any measurement shall be within 5% In case,
average exceeds 5% all the stacks shall be rejected and a lumpsum penalty
ofRs.5,000/- be levied on contractor and contractor shall be advised to restack
the ballast after screening.
ii) In case ballast retained on 40 mm square
mesh sieve exceeds 60% limit prescribed in 23.1 (b) above, payment at the
following reduced rates shall be made for the full stack.
-- 95 % of payable rates if
retention on 40 mm sq. mesh sieve is between 60% (excluding) and 65%
(including)
-- 90% of payable rates if
retention on 40mm sq. mesh sieve is between 65% (excluding) and 70%
(including).
iii) In case retention on 40mm square mesh sieve exceeds 70% the stack,
shall be rejected.
iv) In case of hand broken ballast supply, 40mm.sieve analysis may not be
carried out. The executive may however ensure that the ballast is well graded
between 65mm and 20mm size.
2.3.3.
Under size Ballast: The Ballast shall be treated as undersize and shall
be rejected if:-
i)
Retention on 40mm Sq Mesh sieve is less than 40%.
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Retention on 20mm square mesh sieve is less than 98% (for machine crushed) or
95% (for hand broken)
2.3.4 Method of Sieve
Analysis-
i) The Screen for sieving the ballast shall
be of square mesh and shall not be less than 100 cm in length, 70cm in breadth
and 10cm in height on sides. The following tolerances in the
size of holes for 65, 40 and 20mm sieve shall be permitted:
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65mm Square Mesh Sieve
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Plus Minus 1.5mm
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40mm Square Mesh Sieve
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Plus Minus 1.5mm
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20mm Square Mesh Sieve
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Plus Minus 1.0 mm
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The
Squareness of the individual hole in the sieves viz. 65. 40 and 20mm should he
ensured. Railways may issue necessary instructions in this regard. The sieves
to be used for the ballast measurement shall be obtained from approved
suppliers for which railway shall have a list and mention the same in the
tender documents.
ii) While carrying out sieve analysis, the
screen shall not be kept inclined, but held horizontally and shaken vigorously.
The pieces of ballast retained on the screen can he turned with hand to
see if they pass through but should not be pushed through the sieve.
Hi) The percentage passing through or retained
on the sieve shall be determined by volume by water displacement
method
3 CONDITIONS
FOR SUBMISSION OF TENDER:
3.1 Each tenderer at the time of tendering
shall submit the test report of Impact Value, Abrasion Value, Water Absorption
Value from approved laboratories and the list of these Laboratories shall be
mentioned in the tender documents.
3.2 The
tenderer shall also furnish an undertaking as incorporated in the tender
document that the ballast supply at all times will conform to Specifications
for Track Ballast as specified by Railway.
4. METHOD
OF MEASUREMENT:
4.1 STACK MEASUREMENT:
Stacking shall be done on a
neat, plain and firm ground with good drainage. The height of stack shall not
be less than 1m except in hilly areas where it may be 0.55m. Top width of stack
shall not be less than 1.0m. Top of stack shall be kept parallel to the ground
plane. The side slopes of stack should not be flatter than 1.5:1 (Horizontal :
Vertical) Cubical content of each stack shall normally be not less than 30 cum
in plain areas and 15 cum in hilly areas.
4.2 WAGON MEASUREMENT:
In case of ballast supply
taken by direct loading into wagons, a continuous white & line should be
painted inside the wagon to indicate the level to which ballast I should be loaded. .The cubical content in
cubic meter corresponding to white line I
should also be painted on both sides outside the wagon.
4.2.1 In addition to painted line, mentioned in para 4.2.1, short pieces
of flats (cut pieces of tie bars or other wise) shall be welded at the centre
of all the four sides as shown below as permanent reference.
4.3
SHRINKAGE ALLOWANCE:
Payment shall be made for
the gross measurement either in stacks or in wagons without any deduction for
shrinkage/voids. However, when ballast supply is made in wagons, shrinkage upto
8% shall be permitted while verifying the quantities at destination.
5. SAMPLING AND
TESTING:
A minimum of 3 samples of
ballast for sieve analysis shall be taken for measurement done o n any
particular date even if the numbers of stacks to be measured are less than
three.
5.2 The
test viz., determination of Abrasion Value, Impact Value and Water Absorption
should be got done through approved laboratories or Railway's own laboratories
(List of these laboratories shall be mentioned in the tender document.)
5.3 In order to ensure supply of uniform
quality of ballast, the following norms shall be followed in respect of
sampling, testing and acceptance.
5.3.1 On supply
of the first 100 cum, the tests for size gradation. Abrasion value, Impact
value an, water absorption (if prescribed) shall be carried out by Railway.
Further Supply shall be accepted only after this ballast satisfies the
specifications for these tests. Railway reserves the right to terminate the
contract as per GCC at this stage itself in case the ballast supply fails to
conform with any of these specifications.
5.3 2
Subsequent tests shall be carried out as follows:
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Supply
in stacks
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Supply
in wagons.
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For
stack of volume less than 100 cum
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For
stack of volume more than 100 cum
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a) Size
and Gradation Tests.
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- No of Tests
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One for
each stack
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One for
each stack
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One for
each stack
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- Size
of one sample
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**0.027
cum
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** 0.027
cum for every 100 cum or part thereof
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**0.027
cum
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b)
Abrasion Value
Impact
Value and Water Absorption test @ Testing Frequency
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One test
for every 2000 cum
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** This
sample should be collected using a wooden box of internal dimensions
0.3mx0.3mx0.3m from different parts of the stack/wagon.
@ These
tests shall be done for the purpose of monitoring quality during supply. In
case of the test results not being as per the prescribed specifications at any
stage, further supplies shall be suspended till suitable corrective action is
taken and supplies ensured as per specifications.
The above
tests may be carried out more frequently if warranted at the discretion of
Railway.
5.3.3 All tests
for Abrasion value Impact value and water absorption conducted subsequently to award of contract shall be
done at Railway's cost.
Annexure -1
Aggregate Abrasion Value
(Based on
IS.-2386 part IV-1963)
1 Apparatus
1.1 The abrasion test for track ballast shall
be carried out using Los-Angeles machine as per fig -1
1.2 The abrasive charge shall consist of 12
nos. cast iron or steel spheres approx. 48mm dia and each weighing between 390
and 445 gm ensuring total weight of charge as 5,000 ± 25 gm
1.3 IS sieves of sizes 50mm, 40mm, 25mm and
1.70mm.
1.4 Drying Oven
2. Test Sample
2.1 The test sample of 10,000gm shall consist
of clean ballast conforming to the following grading.
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Passing 50mm and retained on
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40 mm
square mesh sieve
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5,000 gm@
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Passing 40 mm and retained on
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25mm
square mesh sieve
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5,000 gm@
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tolerance of± 2% permitted.
2.2 The sample shall be dried in oven at 100 -
110 °C to a constant weight and weighed (Weight 'A')
3. Test Procedure
The test sample and the abrasive charge shall be placed in the
Los-Angeles abrasion testing machine and the machine rotated at a speed of 20 -
33 revolutions/minute for 1000 revolutions. At the completion of test, the
material shall be discharged and sieved through 1.70mm IS sieve.
4. Analysis
and reporting of the Result
4.1 The material coarser
than 1 70 mm IS sieve shall be washed, dried in oven at 100-110 °C to a
constant weight and weighed (weight B).
4.2 The proportion of loss between Weight
"A" and Weight "B" of the test sample shall be expressed as
a percentage of the original weight of the test sample. This value shall be
reported as:
Aggregate
Abrasion Value =
X 100
Annexure - 2
Aggregate Impact Value
(Based on
18:2386 part IV - 1963)
1. Apparatus
The
apparatus shall consist of the following:
a) Impact testing machine conforming to
IS.2386 part IV - 1963 as per fig. - 2.
b) IS Sieves of sizes 12.5mm,10mm and 2.36mm.
c) A cylindrical metal measure of 75mm dia.
& 50mm depth.
d) A tamping rod 10mm circular cross section
and 230mm k rounded at one end.
e) Drying oven
2. Test Sample
2.1 The test sample shall be prepared out of
track ballast so as to conform to following grading:
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- Passing 12.5mm IS sieve
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100%
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- Retention 10mm IS sieve
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100%
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2.2 The sample shall be oven dried for 4 Hours
at a temperature of 100 - 110°C and cooled.
2.3 The measure shall be filled about
one-third full with the prepared aggregate and tamped with 25 strokes of the
tamping rod. A further Familiar
quantity of aggregate shall be added and a further tamping of 25 strokes given.
The measure shall finally be filled to overflowing, tamped 25 times and the
surplus aggregate struck off, using and tamping rod as a straight edge. The net
weight of the aggregate in the measure shall be determined to the nearest gm.
(weight ‘A')
3. Test Procedure
3.1 The cup of impact testing machine shall be
fixed firmly in the position on the base of the machine and the whole of the
test sample placed in it and compacted by 25 strokes of the tamping rod.
3.2 The hammer shall be raised 380mm above the
upper surface of the aggregate in the cup and allowed to fall freely on to the
aggregate. The test sample shall be
subjected
to a total of 15 such blows, each being delivered at an interval of not less
than one second
4. Analysis and Reporting of the result
4 1 The sample shall be removed and sieved
through 2 36mm IS sieve The fraction passing through shall be weighed (Weight
"B") The fraction retained on the sieve shall also be weighed (Weight
C) and if the total weight (B+C) is less than the initial weight (Weight
"A") by more than one gm, the result shall be discarded and a fresh
test made
4 2 The ratio of the weight of the fines formed
to the total sample weight shall be expressed a s a percentage
Aggregate
Impact Value = B/A X 100
4 3 Two such tests shall be carried out and
the mean of the results shall be reported to the nearest whole number as the
Aggregate Impact Value of the tested material.
Annexure-3
Water Absorption
(Based on
IS:2386 part HI - 1963)
1. Apparatus
The
apparatus shall consist of the following:
a) Wire
Basket - Perforated, electroplated or plastic coated, with wire
bangers for suspending it from the balance.
b) Water
tight container for suspending the basket.
c) Dry
soft Absorbent cloth 75x45 cm size 2 Nos.
d) Shallow
Tray of minimum 650 square cm area.
e) Air tight container of
capacity similar to basket.
f) Drying Oven.
2. Test Sample
A sample
of not less than 2000gm shall be used.
3. Test procedure
3.1 The sample shall be thoroughly washed to
remove finer particle and dust, drained and then placed in the wire basket and
immersed in distilled water at a temperature between 22 -32 °C.
3.2 After immersion the entrapped air shall be
removed by lifting the basket and allowing it to drop 25 times in 25 seconds.
The basket and sample shall remain immersed for a period of 24 ± Vi hours
afterwards
3.3 The basket and aggregate shall then be
removed from the water, allowed to drain for few minutes, after which the
aggregate shall be gently emptied from the basket on to one of dry clothes and
gently surface dried with the cloth transferring it to second dry cloth when
the first will remove no further moisture. The stone aggregate shall be spread
on the second cloth and exposed to atmosphere (away from direct sunlight) until
it appears .,0 be completely surface dry. The aggregate then shall be weighed
(weight "A")
3.4 The aggregate shall then be placed in an
oven at a temperature of 100 - 110°C for 24 hours It shall then be removed from
oven, cooled and weighed (weight "B")