Aggregate Crushing Test

• Aggregate crushing value is the measure of resistance of aggregate to crushing against gradually applied compressive load.
• This test is conducted to determine the crushing strength of aggregate.
• This test helps to assess the suitability of aggregates for use in road construction and other applications where they are subjected to high compressive stresses.
• The specifications for this test are given in IS : 2386 Part IV 1963 mechanical properties.

Procedure

• The material for this test should consist of aggregate passing through 12.5 mm sieve and to be retained on 10 mm sieve.
• About 6.5 kg of sample is placed in the cylinder of the test apparatus and the weight of the material consisting of the test sample is measured as (A).
• The whole setup is placed on a compressive testing machine and these aggregates are subjected to a load of 40 tons. 
• The crushed aggregates are removed from the cylinder and are passed through 2.36 mm sieve. The fraction passing through the sieve is measured as (B)

Aggregate crushing value (ACV) =  B/A x 100

Where B =  weight of aggregate passing through 2.36 mm sieve

A = weight of the surface dry sample taken in mould

Note

ACV 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 airfield pavements.Fig