Deval Attrition Test on Aggregate

1. objective

Attrition test is carried out to test the hardness property of aggregates. The principle of Deval Attrition test is to find the percentage wear due to relative rubbing action between the aggregate and steel balls used as abrasive charge with or without the presence of surface water.

2. apparatus required

3. reference

IS 2386(Part 4):1963 Methods of Test for Aggregates for Concrete- Mechanical Properties. Reaffirmed- Dec 2016

4. procedure

  1. The test sample consists of dry coarse aggregates. The sample should conform to any of the gradings shown in Table 1.
    Grading Passing IS Sieve (mm) Retained on IS Sieve (mm) Percentage of Sample
    A 20 12.5 25
    25 20 25
    40 25 25
    50 40 25
    B 20 12.5 25
    25 20 25
    40 25 50
    C 20 12.5 50
    25 20 50
    D 12.5 4.75 50
    20 12.5 50
    E 10 4.75 50
    12.5 10 50

    Table 1: Gradation of Aggregate (A to E)

  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. The weight of the test sample shall depend upon its average specific gravity and shall be as follows:
    Range in Specific Gravity Weight of sample (g)
    Over 2.8 5500
    2.4 to 2.8 5000
    2.2 to 2.39 4500
    Lerss than 2.2 4000

    Table 2 : Weight of Sample to be taken based on Specific Gravity

  4. Rotate the machine at a speed of 30 – 33 revolutions per minute. The number of rotations is 10000. The machine should be balanced and driven such that there is uniform peripheral speed.
  5. The machine is stopped after the desired number of revolutions and material is discharged to a tray.
  6. The entire stone dust is sieved on 1.70 mm IS sieve.
  7. The material coarser than 1.7 mm size is washed, dried and weighed correct to one gram.

5. calculation

  1. Original weight of aggregate sample (W1) =
  2. Weight of aggregate sample retained (W2) =
  3. Weight passing 1.7mm IS sieve (W1 - W2) =
  4. Attrition value = (W1-W2)*100/W1 =

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