How To Carry Out Abrasion Test
Abrasion test is a type of state carried out on stone aggregates used for road construction. Abrasion is a medical term which means a type of wound incurred by the skin rubbing against a hard surface. Similarly abrasion test is a type of test carried out by rubbing a material or materials (in this case, stone aggregates) at a specific weight and speed to determine at what point the material (s) begin(s) to wear.
The test result indicate the suitability of stones against the grinding action of traffic. Tests used to determine the abrasion resistance of aggregates include;
Los Angeles Abrasion Test.
Deval Abrasion Test.
Dorry’s Abrasion Test.
Los Angeles Abrasion Test is the most widely used and the most preferred of these as it gives test results that are consistent with the performance of pavements.
How To Carry Out The Los Angeles Abrasion Test [Procedure]
The Los Angeles Abrasion Test Apparatus is made up of a hollow cylinder, 700mm inside diameter, and 500mm long. It is closed at both ends of its length. The apparatus is mounted on a frame so that it can be rotated about the horizontal axis. Together with the specified weight [390-445g] of specimen, a specified number of cast iron balls [usually between 6-12], 48mm in diameter are placed in the cylinder.
The cylinder is rotated at a speed of 30 to 33rpm for a specified number of times [500 – 1000].
The aggregates are removed and sieved through sieve 1.7mm. The weight of aggregate passing is determined.
Hence, Los Angeles Value = [weight of aggregate passing through sieve/original weight]/100.
For road works, the following values are recommended:
Base course -50%
Bituminous mixes -30%