Tests on Aggregate
Impact Value Test
Code: This test is done as per IS: 2386 (Part IV) – 1963.
PREPARATION OF SAMPLE:
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i)
The test sample should conform to the following grading:
– Passing through 12.5mm IS Sieve – 100%
– Retention on 10mm IS Sieve – 100% - ii) The sample should be oven-dried for 4hrs. at a temperature of 100 to 110oC and cooled.
- iii) The measure should be about one-third full with the prepared aggregates and tamped with 25 strokes of the tamping rod.
- iv) A further similar quantity of aggregates should be added and a further tamping of 25 strokes given. The measure should finally be filled to overflow, tamped 25 times and the surplus aggregates struck off, using a tamping rod as a straight edge. The net weight of the aggregates in the measure should be determined to the nearest gram (Weight ‘A’).
Procedure:
- i) The cup of the impact testing machine should be fixed firmly in 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.
- ii) The hammer should be raised to 380mm above the upper surface of the aggregates in the cup and allowed to fall freely onto the aggregates. The test sample should be subjected to a total of 15 such blows, each being delivered at an interval of not less than one second.
Uses:
Used to determine the Impact Value of aggregate.