AGGREGATE ABRASION VALUE TEST or LOS ANGELES ABRASION VALUE TEST OF AGGREGATE 



        Hi friends, you are welcomed in the world of Civil Allied Gyan. In this article I have explained about abrasion value test of coarse aggregates.

By the help of this blog you can easily find the abrasion value of given aggregates. So please continue to the end & keep your love and support on me.


The abrasion value of the aggregates is determined in order to determine their Resistance against wearing. In this the aggregate sample is mixed with abrasive charge consisting standard balls & rotated in closed inclined cylinders for specific number of revolutions.

APPARATUS REQUIRED FOR THE TEST:-
  • Los Angeles Machine:- It consists of a hollow steel cylinder, closed at both the ends with an internal diameter of 700 mm and length 500 mm and capable of rotating about its horizontal axis.
  • Cast iron or steel balls, approximately 48 mm in diameter and each weighing between 390g to 445 g; 6 to 12 balls are required.
  • IS sieve
  • Balance 

  • IS: 2386 (Part IV) – 1963
  • IS: 383-1970


PROCEDURE OF THE TEST:-
  1. The test sample shall consist of clean aggregate which has been dried in an oven at 105 °C to 110 °C to substantially constant weight and shall conform to one of the grading shown in Table.
  2. The grading or grading used shall be those most nearly representing the aggregate furnished for the work.
  3. 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.
  4. 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.
  5. The machine shall be so driven and so counter-balanced as to maintain a substantially uniform peripheral speed.
  6. If an angle is used as the shelf, the machine shall be rotated in such a direction that the charge is caught on the outside surface of the angle.
  7. 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 1.70 mm IS sieve.
  8. The material coarser than the 1.70 mm IS Sieve shall be washed dried in an oven at 105 °C to 110°C to a substantially constant weight, and accurately weighed to the nearest gram.


TABULAR COLUMN :-

Grading
Number of Spheres
Weight of Charge (g)
A
12
5000  25
B
11
4584  25
C
8
3330  20
D
6
2500  15
E
12
5000  25
F
12
5000  25
G
12
5000  25



Table:- Gradings of Test Samples


https://civilalliedgyan.blogspot.com/2020/03/abrasion-value-test-of-coarse-aggregates.html



OBSERVATIONS :-

Table:- 


Trail 1
Trail 2

Total weight of dry sample taken= W1 g




Weight of portion passing 1.7 mm sieve= W2 g




Aggregate abrasion value = (W2/W1) x 100(%)