AGGREGATE IMPACT VALUE TEST

GOAL;

Aggregates Impact Value test is conduct to determine the impact value of coarse aggregates, which pass through 12.5 mm. IS sieve and retained on 10 mm. IS sieve

REFERENCE STANDARDS;

IS: 2386 (Part IV) – 1963. Method of test for Aggregates

EQUIPMENT & APPARATUS;

1. Aggregate Impact Test Machine
2. Sieves (12.5mm to 10mm)
3. Balance (0-10kg)
4. Oven(3000c)
5. Cylindrical metal measure
6. Tamping Rod(230 mm length & 10 mm dia. )

PREPARATION OF SAMPLE;

1. The test sample consist of aggregate passing through 12.5mm IS sieve and retained on a 10mm IS sieve, and washed,
2. The aggregates sample should be oven-dried for 4 hours and cooled at a temperature of 100 to 110^oC.
3. Filled cylinder steel cup with One-3rd of equal layer of aggregates, compact each layer of aggregates by tamping rod 25 times and remove the surplus aggregates, using a straight edge of tamping rod horizontally.
4. The net weight of aggregate in the measure should be determined to the nearest gram (W1).

PROCEDURE TO DETERMINE AGGREGATES IMPACT VALUE;

1. Fix the cup firmly in the correct position on the base of the machine and the whole of the aggregates sample is place in it and compacted by a single tamping of 25 gentle stroke of tamping rod.
2. The hammer should be rise up to 380mm from the surface of the aggregates simple in the cup and allowed to fall freely onto the aggregates simple. The aggregates test simple should be subjected to total of 15 such blow, each blow delivered at an interval of not less than one second.
3. Removed the crushed aggregates simple from the cup and sieve on 2.36.IS sieve until no further significant amount passes in one minute. 
4. The fraction passing through sieve is weighed to an accuracy of 0.1 gm and also weighs the friction kept in the sieve.(W2)
5. The result should be discarded if the total weight is less than the initial weight. 

AGGREGATES IMPACT VALUE =W2 / W1 X 100

Total weight of dry sample ( W1 gm)

Weight of portion passing 2.36 mm sieve (W2 gm)