Los Angeles Abrasion test on Aggregates

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

APPARATUS: 

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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: 

Screenshot (270)

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

Screenshot (271)

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.

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Whole Los Angeles test in one  picture

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ALSO READ:-

  1. Los Angeles Abrasion test on Aggregates
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  3. Bitumen content test

 

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