Aggregates undergo substantial wear and tear throughout their life. Generally, they should be hard and tough enough to resist crushing, degradation and disintegration from any activities.

This test is performed by AASHTO T96 or ASTM C131: for resistance to small size coarse aggregation by abrasion and impact in a Los Angeles machine.

Los Angeles's abrasion  test on aggregates is a measure of aggregate toughness and abrasion resistance such as crushing, corrosion and disintegration. Aggregate abrasion characteristics are important because the component aggregates in HMA (Hot Mix Asphalt) must resist crushing, degradation, and disintegration to produce high quality HMA.

Principle of the Test:

To produce the abrasive action by use of standard steel balls which when mixed with the aggregate and rotated in a drum for specific number of revolution cause impact on aggregate. The %age wear due to rubbing with steel balls is determined and is known as abrasion value.

Prepare the sample by the portion of an aggregate sample retained on the 1.70 mm sieve and place in a large rotating drum that contains a shelf plate attached to the outer wall.

Apparatus required:

1.Steel Spherical Balls- Cast iron or steel balls, approximately 48mm in diameter and each weighing between 390 to 445 g; six to twelve balls are required.

2.Los Angeles Machine (The machine is equipped with a counter. The machine shall consist of hollow steel cylinders closed at both ends. An opening shall be provided in the cylinder to present the specimen.

3.Sieves-1.70, 2.36, 4.75, 6.3, 10, 12.5, 20, 25, 40, 50, 63, 80 mm IS Sieves.

4.Balance of capacity 5 kg or 10 kg.

5.Drying oven and tray.

abrasion spherical balls

 Los Angeles Abrasion Test

Procedure for Los Angeles Test:

1.The test specimen consists of clean aggregates dried in an oven at 105 ° - 110 ° C. The sample must correspond to any of the grading shown in Table 1.

2.Select the grading used in the test in such a way that it conforms to the grading used in the construction, to the maximum extent possible.

3.Take a sample of 5 kg for grading A, B, C and D and 10 kg for grading E, F & G.

4.Depending on the grading of the aggregate, choose the abrasive charge according to Table 2.

5.Place aggregates and abrasive charges on the cylinder and fix the cover.

6.Rotate the machine at a speed of 30 to 33 revolutions per minute. The number of revolutions is 500 for A, B, C and D and 1000 for grading E, F & G. The machine must be balanced and operated so that there is equal peripheral speed.

7.The machine is stopped after the desired number of revolutions and  the material is discharged into a tray.

8.The entire stone dust is sieved on a 1.70 mm IS sieve.

9.A material thicker than 1.7 mm in size weighs up to one gram.

Table-1:Grading of test samples

Test Suitability:

The L.A. Abrasion test is an empirical test; it is not directly related to field performance of aggregates.

Field observations generally do not show a good relationship between L.A. abrasion values and field performance.

 L.A. abrasion loss is unable to predict field performance.

sieve sizes
Table 2- Abrasion charge

Uses & Significance 
of Los Angeles Abrasion Test :

For an aggregate to perform satisfactory in pavement, it must be sufficiently hard to resist the abrasive effect of traffic over long period of time. The soft aggregates will be quickly ground to dust, whilst the hard aggregates are quite resistant to crushing effect. 

The test also will determine the quality of the aggregate.

The L.A. Abrasion test is widely used as an indicator of the relative quality or competence of mineral aggregates.

Recommended Los Angeles Test Values for Pavements

Los Angeles test is commonly used to evaluate the hardness of aggregates. The test has more acceptability because the resistance to abrasion and impact is determined simultaneously.

Depending upon the value, the suitability of aggregates for different road constructions can be judged as per IRC specifications as given:


Type of Pavement

Max. permissible abrasion value in %


Water bound macadam sub base course



WBM base course with bituminous surfacing



Bituminous bound macadam



WBM surfacing course



Bituminous penetration macadam



Bituminous surface dressing, cement concrete surface course



Bituminous concrete surface course


Observations of Los Angeles Test: 

Original weight of aggregate sample = W1  gm

Weight of aggregate sample retained = W2 gm

Weight passing 1.7mm IS sieve = W– Wgm

Abrasion Value = (W– W) / WX 100


abrasion test values
Table-3: Abrasion test values


Average Los Angeles Abrasion Value (from table-3) = 14.94 

Note: The reading will be different whenever you will perform the los angeles test. In this article, i have given the readings and it calculations for computing average abrasion values so that it will be helpful for the students undergoing civil engineering degree.

Post a Comment

Previous Post Next Post