Wednesday, August 26, 2020

Los Angeles Abrasion Test

os Angeles abrasion test is the very important test on aggregates which measures the toughness and abrasion resistance Of aggregate such as crushing,

Los Angeles Abrasion Test

Los Angeles abrasion test is the very important test on aggregates which measures the
toughness and abrasion resistance Of aggregate such as crushing, degradation and
disintegration.The Los Angeles abrasion test is carried out by Using the guidelines
of AASHTO T 96 or ASTM C 131: Resistance to Degradation of Small-Size Coarse
Aggregate by Abrasion.
The aggregate used in Base course, Sub base course & surface course of the highway

pavements are subjected to wearing due to movement of traffic.When vehicles move on the road,  abrasion of road aggregates are caused by the wearing action between the wheel of vehicle and the road surface.The steel rimmed wheels of animal driven vehicles also considerable cause for abrasion of the road surface.
Los angles image

Therefore, the road aggregates should be hard enough to withstand the abrasion. Resistance due to abrasion of aggregate can be determined in laboratory by Los Angeles test machine.The principle of Los Angeles abrasion test is to produce abrasive action or wearing action by use of standard steel balls which when mixed with aggregates and rotated in a drum for specific number of revolutions also causes impact on aggregates as maintain in Standards Code.

The percentage of wear of the aggregates due to abrasion with steel balls is determined as Los Angeles Abrasion Value.

APPARATUS :-

  • Los Angles apparatus, 
  • IS Sieve, 
  • Weighting Balance

PROCEDURE :-

  1. Clean and dry the aggregate sample of the grading A to G is used for the test.
  2. Aggregate weighing 5kg for grading A, B, C or D and 10Kg for grading E, F or G may be taken as test specimen and placed in the cylinder.
  3. The wearing or abrasion of the test sample is also chosen accordingly and placed in the cylindrical bracket of the machine, and cover is fixed to make dust tight.
  4. The machine is rotated at a speed of 30 to 33 revolutions per minute.
  5. The machine is rotated for 500 revolutions for gradings A, B, C and D, for gradings E, F and G, it shall be rotated for 1000 revolutions.
  6. After the desired number of revolutions the machine is stopped and entire test sample & stone dust are extracted carefully from the cylindrical bracket of the machine.
  7. Using a sieve of size larger than 1.70mm IS sieve, the material is first separated into two parts and the finer position is taken out and sieved further on a 1.7mm IS sieve.
  8. Let the original weight of aggregate be W1gm, weight of aggregate retained on 1.70mm IS sieve after the test be W2gm.

OBSERVATION & CALCULATION :-

Los angles table image

RESULT :-

The average value of Los Angles Abrasion Test is ________________%.


PRECAUTIONS :-

  1. Use a coarser sieve first in order to minimize wear of 1.7 mm I.S. sieve.
  2. The sieving operation should be conducted by means of a lateral and vertical motion of the sieve, accompanied by the jarring action so as to keep the sample moving continuously over the surface of the sieve. In no case shall the fragments of the sample be turned or manipulated though the sieve by hand. 




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