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Los Angeles Abrasion Test
Abrasion test, also known as Los Angeles abrasion test, is widely used to check the relative quality of aggregates. It is used to measure the hardness and abrasion resistance of aggregates such as crushing, degradation and disintegration.Obective
Following are the objectives of the Los Angeles abrasion test:
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- To find the Los Angeles abrasion value of the aggregates.
- To check if the particular aggregate sample is suitable for use in road construction.
Apparatus
According to IS: 2386 (part 4) – 1963 the apparatus consists of: 1. Los Angeles abrasion machine.Los Angeles Abrasion Test Procedure
The procedure of the abrasion test is given below: 1. First, select the grading size of aggregates to be used in the test such that it conforms to the grading to be used in construction. 2. The sample of aggregates is separated according to individual size fractions of the required masses. 3. Place the aggregate sample in the Los Angeles abrasion machine and start rotating at a speed of 30 to 33 rotations per minute (rpm). 4. Now remove the aggregate sample from the Los Angeles machine and wash over a 1.70 mm (no. 12) sieve and place it in the oven to dry.Observations
Following are the observations acquired from the Los Angeles abrasion test: Original weight of aggregate sample = W1 grams Weight of aggregate sample retained on the sieve = W2 gramsIndian Standard Recommended Los Angeles Abrasion Value For Road Pavements
Indian standard codes have determined maximum permissible abrasion values for different types of road pavements. So, It should not exceed the maximum permissible abrasion value, given by IS codes. If the value exceeds the maximum permissible abrasion value, then that particular sample of aggregates is rejected and is considered unsuitable for using pavements. The maximum permissible abrasion values are expressed in percentage (%). Let us see the maximum permissible abrasion values for various types of pavements, specified by Indian standards. They are as given below:Sl. No. | Type Of Pavement | Maximum Los Angeles Abrasion Value (%) |
1. | Water bound macadam sub base course | 60 % |
2. | Water bound macadam base course with bituminous surfacing | 50 % |
3. | Bituminous bound macadam | 50 % |
4. | Water bound macadam surfacing course | 40 % |
5. | Bituminous penetration macadam | 40 % |
6. | Bituminous surface dressing, cement concrete surface course | 35 % |
7. | Bituminous concrete surface course | 30 % |