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Questions and Answers
What must be tested on the supply of the first 100 cum of ballast?
What must be tested on the supply of the first 100 cum of ballast?
One test for Abrasion Value, Impact Value, and Water Absorption should be conducted for every _____ cum of ballast.
One test for Abrasion Value, Impact Value, and Water Absorption should be conducted for every _____ cum of ballast.
2000
What dimensions should the wooden box used for sample collection have?
What dimensions should the wooden box used for sample collection have?
0.3m x 0.3m x 0.3m
Subsequent tests for size gradation in ballast supply are only conducted if the supply is in stacks of more than 100 cum.
Subsequent tests for size gradation in ballast supply are only conducted if the supply is in stacks of more than 100 cum.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Retention on the 40mm square mesh sieve must be at least 40% for the ballast to be accepted.
Retention on the 40mm square mesh sieve must be at least 40% for the ballast to be accepted.
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What percentage reduction in contracted rates applies if retention on the 40mm square mesh sieve is between 60% and 65%?
What percentage reduction in contracted rates applies if retention on the 40mm square mesh sieve is between 60% and 65%?
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What is the maximum allowable retention on the 40mm square mesh sieve before the ballast is rejected?
What is the maximum allowable retention on the 40mm square mesh sieve before the ballast is rejected?
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The ballast is considered undersize if the retention on a 20mm square mesh sieve is less than _____ for machine crushed ballast.
The ballast is considered undersize if the retention on a 20mm square mesh sieve is less than _____ for machine crushed ballast.
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Match the retention limits with their corresponding actions:
Match the retention limits with their corresponding actions:
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Study Notes
Ballast Quality Control
- The Railway reserves the right to terminate the contract if the ballast supply fails to meet the specified quality standards.
- The Railway will conduct tests such as size gradation, abrasion value, impact value, and water absorption on the first 100 cubic meters of ballast supplied.
- Subsequent testing frequency for ballast supplied in stacks:
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Size and Gradation Tests:
- One test for each stack for a stack volume of less than 100 cubic meters
- One test for each stack for a stack volume of more than 100 cubic meters
- One test for each wagon regardless of the stack size
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Abrasion Value, Impact Value, and Water Absorption Tests:
- One test for every 2000 cubic meters
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Size and Gradation Tests:
- Samples for testing should be collected using a wooden box with internal dimensions of 0.3m x 0.3m x 0.3m.
- In case of any test results not meeting the specifications, further supplies will be suspended until corrective action is taken.
Ballast Size Specifications
- Ballast retained on a 40mm square mesh sieve (machine-crushed ballast only) exceeding 60% will result in reduced payment:
- 5% reduction for retention between 60% and 65%
- 10% reduction for retention between 65% and 70%
- Ballast with more than 70% retention on the 40mm square mesh sieve will be rejected.
- Hand-broken ballast is exempt from the 40mm sieve analysis, but it must be well-graded between 65mm and 20mm.
- Ballast is considered undersize and will be rejected if:
- Retention on the 40mm square mesh sieve is less than 40%.
- Retention on the 20mm square mesh sieve is less than 98% (for machine-crushed) or 95% (for hand-broken).
Sieve Analysis Procedures
- The sieve analysis procedures are outlined:
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Sieve Sizes:
- Nominal sizes are used, with acceptable tolerances for the holes:
- 65mm Square Mesh Sieve: Plus Minus 1.5mm
- 40mm Square Mesh Sieve: Plus Minus 1.5mm
- 20mm Square Mesh Sieve: Plus Minus 1.0mm
- Nominal sizes are used, with acceptable tolerances for the holes:
-
Sieve Screen:
- Square mesh screen is required with minimum dimensions of 100cm length, 70cm breadth, and 10cm height.
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Sieving Procedure:
- The screen should be held horizontally and shaken vigorously.
- Ballast pieces retained on the screen can be turned by hand to check if they pass through but should not be pushed.
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Percentage Determination:
- The percentage of ballast passing or retained on the sieve is determined by weight.
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Sieve Sizes:
Impact Test Procedure
- A test sample of ballast (approx. 5kg) of size 10 mm to 12.5 mm is required for the impact test.
- The ballast used for the impact test should be randomly selected to avoid bias.
- Alternatively, ballast in the required size range can be manufactured for the test.
Water Absorption Limits
- The Chief Track Engineer (CTE) or Construction Area Officer (CAO) can relax water absorption limits for specific areas.
- Regardless of relaxation, the maximum allowable water absorption is 2.5%.
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Description
This quiz covers the essential quality control measures for ballast supply in railway projects. It includes testing specifications, acceptable limits, and procedures for handling non-compliant material. Prepare to evaluate your understanding of the quality standards required in railway construction.
