Aim
To determine the abrasion value of coarse aggregates as per IS 2386 (Part IV) – 1963.
Apparatus
1- Los Angles abrasion testing machine
2- IS Sieve of size – 1.7mm
3- Abrasive charge – 12 nos. cast iron or steel spheres approximately 48mm dia. and each weighing between 390 and 445g ensuring that the total weight of charge is 5000 + or – 25g
4- Oven
Preparation of sample
The test sample should consist of clean aggregates which have been dried in an oven at 105 to 110ºC to a substantially constant weight and should conform to one of the gradings shown in the table below:
Procedure
The test sample and the abrasive charge should be placed in the Los Angles abrasion testing machine and the machine rotated at a speed of 20 to 33 revolutions/minute for 1000 revolutions. At the completion of the test, the material should be discharged and
sieved through 1.70 mm IS Sieve.
Results
1-The material coarser than 1.70 mm IS Sieve should be washed, dried in an oven at a temperature of 100 to 110ºC to a constant weight and weighed (Weight ‘B’).
2-The proportion of loss between weight ‘A’ and weight ‘B’ of the test sample should be expressed as a percentage of the original weight of the test sample. This value should be
reported as
Aggregate abrasion value = {(A-B)/A} x 100%
A sample proforma for the record of the test results is given in the below table
Discussion
1-Hardness is an important property of aggregates used in the construction of highways and railroads.
2- Los Angeles combines the process of abrasion and attrition.
