• Aggregate impact value is the measure of the resistance of an aggregate to sudden shock or impact.
  • This test is conducted to determine the toughness of aggregates.
  • This test helps to evaluate the quality of aggregates which can be used in road construction.
  • The specifications for this test are given in IS : 2386 Part IV 1963 mechanical properties.


  • The aggregates used for this test should pass through IS 12.5 mm sieve and should retain on IS 10 mm sieve.
  • The oven dried sample should be filled by one- third full and tamped with 25 strokes by a tamping rod.
  • The above procedure is repeated until the cup is finally filled to overflowing, tamped 25 times and the excess aggregate is struck off.
  • The net weight of the aggregate is determined as (A).
  • A total of 15 blows are delivered to the upper surface of the aggregate by the hammer which is raised and freely released on the aggregate sample.
  • The crushed aggregate is removed from the cup and the whole of it is sieved on  2.36 mm sieve.
  • The fraction passing through the sieve is weighed as (B) and the fraction retained on the sieve is weighed (C).
  • If the total weight (B+C) is less than the initial weight (A), the result shall be discarded and a fresh test made.
impact value test

Aggregate Impact Value (AIV) = B/A x 100

Where B =  weight of aggregate passing through 2.36 mm sieve

A = weight of the oven – dried sample


AIV should not be more than 45% for use in concrete other than wearing surfaces, and 30% for concrete used for wearing surfaces such as roads, runways and pavements.

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