#arvinvawhale #concretetechnology #determinationofabrasionvalue #Losangelesmachine
The abrasion value of the aggregates is determined in order to determine their Resistance against wearing. The test involves taking specified quantity of standard size material along with specified number of abrasive charge in a standard cylinder and revolving if for certain specified revolutions. The particles smaller than 1.7 mm size is separated out. The loss in weight expressed as percentage of the original weight taken gives the abrasion value of the aggregate. The abrasion value should not be more than 30 per cent for wearing surfaces and not more than 50 per cent for concrete other than wearing surface.
However, the use of Los Angeles abrasion testing machine gives a better realistic picture of the abrasion resistance of the aggregate. Lower the aggregate abrasion value stronger the aggregate against wear .
Test sample and abrasive charge are placed in the Los Angeles Abrasion testing machine and the machine is rotated at a speed of 20 to 33 rev/min. For grading A, B, C and D, the machine is rotated for 500 revolutions.
For grading E, F and G, it is rotated 1000 revolutions.
PROCEDURE:
1. The test sample shall consist of clean aggregate which has been dried in an oven at 105 to 110°C to substantially constant weight and shall conform to one of the grading shown in Table. The grading or grading used shall be those most nearly representing the aggregate furnished for the work.
2. The test sample and the abrasive charge shall be placed in the Los Angeles abrasion testing machine and the machine rotated at a speed of 20 to 33 rev/min. For grading A, B, C and D, the machine shall be rotated for 500 revolutions; for grading E, F and G, it shall be rotated for 1000 revolutions.
3. At the completion of the test, the material shall be discharged from the machine and a preliminary separation of the sample made on a sieve coarser than the l.70 mm IS
Sieve.
4. The material coarser than the 1.70 mm IS Sieve shall be washed dried in an oven at 105 to 110°C to a substantially constant weight, and accurately weighed to the nearest gram

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