Used for testing of coarse aggregates, with a maximum size smaller than 37.5 mm (1-½”), for resistance to degradation. It is considered as an indicator of the relative quality or competence of various sources of aggregate having similar mineral compositions.

A combination of actions including abrasion or attrition, impact, and grinding in a rotating steel drum containing a specified number of steel spheres along with the test specimen. As the drum rotates, a shelf plate picks up the sample and the steel spheres, carrying them around until they are dropped to the opposite side of the drum, creating an impact crushing effect. The contents then roll within the drum with an abrading and grinding action until the shelf plate picks up the sample and the steel spheres, and the cycle is repeated. After the prescribed number of revolutions, the contents are removed from the drum and the aggregate portion is sieved to measure the degradation as percent loss.

Consists of a hollow steel cylinder, with a wall thickness of 12.00 mm (1/2”) closed at both ends having an inside diameter of 711.00 mm (28”), and an inside length of 508 mm (20”).

The drum rotates at 31 – 33 rpm.