Los Angeles Abrasion test on Aggregates

AIM:
To determine the abrasion value of coarse aggregates as per IS: 2386 (Part IV) – 1963.

APPARATUS: 

i) Los Angles abrasion testing machine
ii) IS Sieve of size – 1.7mm
iii) 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
iv) Oven 

PREPARATION OF SAMPLE:
The test sample should consist of clean aggregates which has 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:
i) 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’).
ii) 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:

i) Hardness is an important property of aggregates used in construction of highways and railroads.

ii) Los Angeles combines the process of abrasion and attrition.

Whole Los Angeles test in one  picture

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