01-09-2016, 09:24 AM
Aggregate crushing test:
The aggregate crushing value provides a relative measure of resistance to crushing under
gradually applied crushing load. The test consists of subjecting the specimen of aggregate in
standard mould to a compression test under standard load conditions (Figure 1). Dry aggregates
passing through 12.5 mm sieves and retained 10 mm sieves are filled in a cylindrical measure of
11.5 mm diameter and 18 cm height in three layers. Each layer is tampered 25 times with at
standard tamping rod. The test sample is weighed and placed in the test cylinder in three layers
each layer being tampered again. The specimen is subjected to a compressive load of 40 tonnes
gradually applied at the rate of 4 tonnes per minute. Then crushed aggregates are then sieved
through 2.36 mm sieve and weight of passing material (W2) is expressed as percentage of the
weight of the total sample (W1) which is the aggregate crushing value.
A value less than 10 signifies an exceptionally strong aggregate while above 35 would normally
be regarded as weak aggregates.