Abrasion test is carried out on the stone to check its suitability for road construction. The test results indicate the suitability of the stone against grinding action under traffic.
There are three types of abrasion test are performed to check the suitability of stone aggregates.
Here is the list of these 3 abrasion tests:
- Los Angels Abrasion Test
- Deval Abrasion Test
- Dorsey’s Abrasion Test
Los Angels abrasion test is normally performed because it gave good correlation with the performance of road pavements.
The Los Angeles apparatus consists of a hollow cylinder. The inner diameter of the hollow cylinder is 0.7 m and the length is 0.5 m. The apparatus is hung on a frame so that it can rotate freely about a horizontal axis. A cast iron ball of 48 mm diameter is placed in the cylinder.
The cylinder is rotated at a speed of 30 to 33 RPM for specified numbers of times which is 500 to 1000. Afterthat, stone aggregates is removed and sieved on 1.7 mm Sieve.
In this way weight of passing stone aggregates is found.
Los Angels Value = (Weight of aggregate passing through sieve/Original weight) × 100
The recommended value for road works are as follows:
For Base Course: 50%
For Bituminous Mixes: 30%