What Is Abrasion Test? | Purpose of Abrasion Test | Apparatus Used for Abrasion Test | Procedure For Abrasion Test

all about of Abrasion Test

What Is Abrasion Test?

The compressive strength of any concrete depends on the strength of the aggregates used in it. Therefore strong aggregate is required for the high strength of concrete.

Abrasion tests are performed for aggregates used in construction. Abrasion Test can determine the value of hardness and abrasion resistance for crushing, degradation, and disintegration of aggregates.

This test is prescribed by ASTTO T96 or ASTM C131 to determine the resistance of a small-size coarse aggregate to friction and impact in a Los Angeles machine.

Aggregates are used for various surface courses for road pavements. The movement of heavy traffic causes friction from wear and tear on the surface. (Los Angeles abrasion test ASTM c131).

Therefore, if the aggregate is to be used for the construction of heavy roads, the aggregate must be strong enough to withstand abrasion. The abrasion resistance value of aggregate can be obtained in a laboratory by a Los Angeles testing machine.

Friction action is generated in the drum using standard steel balls for Los Angeles abrasion testing. The balls blend into the drum with the aggregate. The drum is rotated according to a certain number of testing rules. Which has direct impacts on aggregates.

This test determines the percentage of friction in the coarse aggregate of the sample from the friction generated by the steel ball. The value obtained in this way is known as the Los Angeles Abrasion Value.

Purpose of Abrasion Test

  1. Friction can be a major cause of spoilage of any material. The abrasion test can obtain the data needed to compare coatings for friction. Which is useful for obtaining information on the lifespan of your construction product.
  2. The abrasion test can be used to test the abrasion resistance of solids. The use of materials like metals, composites, ceramics, coatings can be detected by this test.

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Determination of Los Angeles Abrasion Value

The Los Angeles abrasion test of a sample of aggregate is performed in a Los Angeles abrasion machine to obtain information for the following purposes.

  1. To find the value of aggregate abrasion by Los Angeles abrasion test.
  2. This is done to achieve the required proper selection of aggregate used in road construction projects.

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Apparatus is classified as follows on the basis of IS: 2386 (Part IV) – 1963

  • Los Angeles abrasion machine.

  • Abrasive ball: which is made from cast iron or steel ball. It has a diameter of about 48 mm and each ball weighs between 390 and 445 grams. At the time of the test, six to twelve balls are placed in the drum along with the material at the time of the test.

Abrasive ball

  • Sieve: This test uses a sieve for analysis up to 1.70mm, 2.36mm, 4.75mm, 6.3mm, 10mm, 20mm, 25mm, 40mm, 50mm, 63mm, 80mm.

Sieve

  • Weight counter.

Weight counter

  • Oven Drying.

Oven Drying

  • Miscellaneous like a tray.

tray

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Procedure For Abrasion Test

  1. Select the grading of the aggregate to be used in the test. The grading of the aggregate used in construction is selected as appropriately as possible.
  2. Take a 5 kg sample of aggregate for grading A, B, C, and D, and a 10 kg sample for E, F, and G grading.
  3. Abrasive charge balls are selected according to Table 1 according to the aggregate grading sample.
  4. The aggregate and standard ball are inserted into the cylinder drum. And its cover is fixed.
  5. The cylinder drum is then rotated by the machine at 30 to 33 rounds per minute. 500 for gradings like A, B, C, and D and 1000 round for E, F, and G grading.
  6. After a certain number of cylinder drums rotates, the automatic machine shuts down The aggregate sample is then discharged into a tray.
  7. The sample discharged from the machine is mounted on an IS sieve of 1.70 mm.
  8. The material discharged in this way weighs more than 1.7 mm and weighs one gram.

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Table 1: Selection of Abrasive Balls

Sr No Grading No of Steel Balls Weight in gm
1 A 12 5000 ± 25
2 B 11 4584 ±25
3 C 8 3330 ± 20
4 D 6 2500 ± 15
5 E 12 5000 ± 25
6 F 12 5000 ± 25
7 G 12 5000 ± 25

Table-2 Format of Abrasion Test Report

Source Tested as per
Weight of sample taken (gms) Confirmation as per
Sieve size  (mm) Weight of test sample in gm A B C D E F G
80.0 mm 63.0 mm
63.0 mm 50.0 mm
50.0 mm 40.0 mm
40.0 mm 25.0 mm
25.0 mm 20.0 mm
20.0 mm 12.5 mm
12.3 mm 10.0 mm
10.0 mm 6.3 mm
6.3 mm 4.75 mm
4.75 mm 2.36 mm
Pan
Remarks ( If Any) –
Contractor PMC Client

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Standard Test Methods of Abrasion Test

  • ASTM C535: This code describes the resistance of aggregates to a large aggregate coarse sample by a Los Angeles machine and its effect on it.
  • This test is prescribed by ASTTO T96 or ASTM C131 to determine the resistance of a small-size coarse aggregate to friction and impact in a Los Angeles machine.

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Uses Of The Abrasion Test

  1. The aggregates should be able to provide a layer for road pavement and resist the abrasive effect of traffic for a long time. For this, an abrasion test is done to select the right aggregate for road pavement.
  2. The use of soft aggregates causes rapid damage to the road pavement. While rigid aggregates are quite resistant to the road pavement. Therefore abrasion test is used to select a strong aggregate.
  3. The total quality of aggregates can also be determined by the abrasion test.
  4. L.A. Abrasion testing is widely used as a classification of the quality or relative suitability of mineral aggregate.

La-Abrasion Test

  • The test is prepared by separating the sample from the set of aggregates to the required size.
  • The prepared samples and the abrasive ball are placed on the machine. And rotates at 30-33rpm.
  • The sample is washed by discharging on a sieve number 12 (1.70 mm). And then put it in the oven to dry.
  • The value of the strength of aggregate can be obtained from the percentage difference between the original mass and the final mass.

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IS Recommended Los Angeles Abrasion Test Values for Pavements

The hardness of aggregate indicates the life of the road pavement. It is tested in Los Angeles to select the right aggregate. The IRC specifications for suitability for different road constructions based on the value of this test are as follows,

SI. No.  Type of Pavement  Max. Permissible Abrasion Value in % 
1 Water bound macadam sub base course 60
2 Bituminous bound macadam 50
3 WBM base course with bituminous surfacing 50
4 Bituminous penetration macadam 40
5 WBM surfacing course 40
6 Bituminous surface dressing, cement concrete surface course 35
7 Bituminous concrete surface course 30

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