Los Angeles Machine

In the Los Angeles test used in the cross-testing experiments reported here, a 5000 +/- 5 g test portion of 10/14 mm aggregate is rolled in a steel drum together with 11 steel balls of total mass 4775 +/- 85 g . The drum has an internal diameter of 710 +/- 3 mm and rotates at 32 +/- 1 r/min . A projecting plate inside the drum lifts some of the steel balls and aggregate each time the drum rotates, so that the steel balls fall, causing the aggregate to be fragmented.

The rolling continues for 500 revolutions, after which the percentage of the test portion that passes a 1.60 mm sieve is determined by washing then sieving. This percentage is the Los Angeles coefficient, described in this Report as being measured in "LA units".