Abrasion test by Los Angeles machine हिन्दी मे

Los Angeles Abrasion Test हिन्दी मे
Abrasion test ! Abrasion test by Los Angeles machine ! Los Angeles machine !
LOS ANGELES ABRASION VALUE TEST AS PER IS 2386 PART 4
Los Angeles Abrasion test in hindi
Los Angeles Abrasion Value Test
Abrasion Value Test/ Los Angeles Test (Aggregate)
Determination of Los Angeles Abrasion Value---
The Los Angeles abrasion test on aggregates are done for following purposes:
1. To determine the Los Angeles abrasion value.
2. To find the suitability of aggregates for use in road construction.
Apparatus for Los Angeles Test
The apparatus as per IS: 2386 (Part IV) - 1963 consists of:
1. Los Angeles Machine
2. Abrasive charge: Cast iron or steel balls, approximately 48mm in diameter and each weighing 3. between 390 to 445 g; six to twelve balls are required.
4. Sieve: 1.70, 2.36, 4.75, 6.3, 10, 12.5, 20, 25, 40, 50, 63, 80 mm IS Sieves.
Balance of capacity 5 kg or 10 kg
5. Drying oven
6. Miscellaneous like tray
Procedure for Los Angeles Test
1. The test sample consists of clean aggregates dried in oven at 105° - 110°C. The sample should conform to any of the gradings shown in table 1.
2. Select the grading to be used in the test such that it conforms to the grading to be used in construction, to the maximum extent possible.
3.Take 5 kg of sample for gradings A, B, C & D and 10 kg for gradings E, F & G.
4. Choose the abrasive charge as per Table 2 depending on grading of aggregates.
5. Place the aggregates and abrasive charge on the cylinder and fix the cover.
6. Rotate the machine at a speed of 30 to 33 revolutions per minute.
7. The number of revolutions is 500 for gradings A, B, C & D and 1000 for gradings E, F & G.
8. The machine should be balanced and driven such that there is uniform peripheral speed.
9. The machine is stopped after the desired number of revolutions and material is discharged to a tray.
The entire stone dust is sieved on 1.70 mm IS sieve.
The material coarser than 1.7mm size is weighed correct to one gram.
Table 1: Grading of Test Samples - *Tolerance of ± 12 percent permitted.
Sieve size (square hole) Weight of test sample in gm
Passing (mm) Retained on (mm) A B C D E F G
80 63 2500*
63 50 2500*
50 40 5000* 5000*
40 25 1250 5000* 5000*
25 20 1250 5000*
20 12.5 1250 2500
12.5 10 1250 2500
10 6.3 2500
6.3 4.75 2500
4.75 2.36 5000
Table 2: Selection of Abrasive Charge
Grading No of Steel balls Weight of charge in gm.
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
Observations of Los Angeles Test
Original weight of aggregate sample = W1 g Weight of aggregate sample retained = W2 g Weight passing 1.7mm IS sieve = W1 - W2 g Abrasion Value = (W1 - W2 ) / W1 X 100 Results Los Angeles Abrasion Value =
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:
Sl. No. Type of Pavement Max. permissible abrasion value in %
1 Water bound macadam sub base course 60
2 WBM base course with bituminous surfacing 50
3 Bituminous bound macadam 50
4 WBM surfacing course 40
5 Bituminous penetration macadam 40
6 Bituminous surface dressing, cement concrete surface course 35
7 Bituminous concrete surface course 30
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