DETERMINATION OF BITUMEN CONTENT IN THE BITUMINOUS MIX

Bitumen Content Test of a Bituminous Mix

Purpose

The test determines the bitumen content in the bituminous mix by cold solvent extraction.

Apparatus & Solvent

  • Centrifuge apparatus
  • Trichloroethylene
Centrifuge apparatus used for binder content test of bituminous mix
Centrifuge apparatus used for binder content test of bituminous mix

Procedure

  1. Take a representative sample of about 500 g, weigh it exactly and place it in the bowl of the extraction apparatus (W1).
  2. Cover the sample with commercial grade trichloroethylene.
  3. Let the mixture stand for about one hour before starting the centrifugal machine.
  4. Weigh the dried filter ring and then fit it around the edge of the bowl. Clamp the cover of the bowl tightly.
  5. Place a beaker under the drain to collect the extract.
  6. The machine is revolved slowly and then gradually the speed is increased to a maximum of 3600 rpm. The speed is maintained till the solvent ceases to flow from the drain.
  7. The machine is allowed to stop, 200 ml of solvent is added and the above procedure is repeated. A number of 200 ml solvent additions (not less than three) are used till the extract is clear and not darker than a light straw colour.
  8. Remove the fitter ring from the bowl, dry it first in the air and then in the oven at 1150C to a constant weight, and weigh it.
  9. Collect back the fine material that might have passed through the filter, by centrifuging. Wash and dry the material to a constant weight, as before.

Calculation

Calculate the percentage of binder in the bituminous mix sample as follows:

Percentage of Binder = [W1 – (W2 + W3 + W4) /W1] x 100

Where

W1 = Weight of the sample, g

W2 = Weight of the sample after extraction, g

W3 = Weight of the fine material recovered from the extract, g

W4 = Increase in weight of filter ring, g

Record all the test data in a form as shown below.

Sample form used to record data of bitumen content test of a bituminous mix
Sample form used to record data of bitumen content test of a bituminous mix
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