Dnyan Deshmukh

Staff member
Ref : IS : 2386 (Part IV)

Purpose : To determine the aggregate impact value.

Preparation of test sample:

a) Take a sample of aggregate passing through 12.5mm sieve and retained on 10mm sieve.

b) Dry the aggregate sample in an oven for a period of four hours at a temperature of 1000C to 1100C and then cool it.

c) Fill the measure in three layers and tamp each layer by 25 strokes of tamping rod.

d) Determine the net weight of aggregate (A) in the measure.

Test procedure:

a) Place the test sample in the cup.

b) Compact the sample by subjecting it to 25 strokes with a tamping rod.

c) Compact the sample by subjecting it to 15 blows of hammer at an interval of not less than one second, raise the hammer 380mm above the upper surface of the aggregate and allow it to fall freely on to the aggregate.

d) Remove the crushed aggregate from the cup.

e) Sieve the aggregate on the 2.36mm sieve.

f) Sieve the aggregate passing through sieve (B).

g) Weigh the aggregate retained on the sieve (C).

h) Discard the result, if the total weight (B+C) is less than the initial weight (A) and make a fresh test sample. Repeat the test twice.


Aggregate Impact value (%) = B/A * 100


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