This test is carried out on stones used as aggregates for road construction. The test result shows the suitability of stones against the grinding action under traffic. Any 1 of the following test can be conducted to find out the suitability of aggregates:
A. Los Angeles abrasion test
B. Deval abrasion test
C. Dorry's abrasion test.
Los Angeles abrasion test is preferred as these test results are with good correlation with the performance of the pavements.
The Los Angeles apparatus consists of a hollow cylinder 0.7 m inside diameter and 0.5 m long having both ends closed. It is mounted on a frame so that it may be rotated about horizontal axis. IS code has standardized the test process for different gradation of specimen. With specified weight of specimen a specified number of cast iron balls of 48 mm diameter are placed in the cylinder.
Los Angeles testing machine
Then the cylinder is rotated at a speed of 30 to 33 rpm for particular number of times (500 to 1000). Then the aggregate is removed & sieved on 1.7 mm. IS sieve. The weight of aggregate passing is found. Then Los Angeles value is calculated as
The following values are recommended for road works:
For bituminous mixes = 30%
For base course = 50%