Bitumen Extraction Test is used to determine the percentage of bitumen content present in the asphaltic pavement by cold solvent extraction.

The properties of flexible pavement such as durability, compatibility, and resistance from defects bleeding, raveling, and aging of flexible pavement are majorly dependent on the percentage of bitumen used with the aggregate to lay the pavement.

Aim of the Test

To determine the binder content (bitumen) in the asphalt mix by cold solvent extraction method.

Code References

  1. IRC: SP 11 –1988 (Appendix – 5)
  2. ASTM D 2172

Apparatus Required

  1. Centrifuge
  2. Balance of capacity 500 grams and sensitivity 0.01grams.
  3. Thermostatically controlled oven with capacity up to 2500 C.
  4. Beaker for collecting extracted material.
Centrifuge for Bitumen extraction test
Fig 1: Centrifuge for Bitumen Extraction Test

Procedure of Test

  1. Take exactly 500 grams of the representative sample and place it in the bowl of the extraction apparatus (W1).
  2. Add benzene to the sample until it is completely submerged.
  3. Dry and weigh the filter paper and place it over the bowl of the extraction apparatus containing the sample (B).
  4. Clamp the cover of the bowl tightly.
  5. Place a beaker under the drainpipe to collect the extract.
  6. Sufficient time (not more than an hour) is allowed for the solvent to disintegrate the sample before running the centrifuge.
  7. Run the centrifuge slowly and then gradually increase the speed to a maximum of 3600 rpm.
  8. Maintain the same speed till the solvent ceases to flow from the drainpipe.
  9. Run the centrifuge until the bitumen and benzene are drained out completely.
  10. Stop the machine, remove the cover and add 200ml of benzene to the material in the extraction bowl and the extraction is done in the same process as described above.
  11. Repeat the same process not less than three times till the extraction is clear and not darker than a light straw color.
  12. Collect the material from the bowl of the extraction machine along with the filter paper and dry it to constant weight in the oven at a temperature of 1050 C to 1100 C and cool to room temperature.
  13. Weigh the material (W2) and the filter paper (D) separately to an accuracy of 0.01grams.

Calculation and Observation

Sl NoObservationSample 1Sample 2Sample 3
1Weight of mix taken before extraction (W1)
2Weight of filter paper before extraction (B)
3Weight of mix after extraction (W2)
4Weight of filter paper after extraction (D)
5Weight of filler collected in filter paper (B-D) =W3

The formula to calculate the percentage of binder content is given by-

Formula for percentage of Binder content

Report

The average percentage of Binder content in the given Bitumen Mix = _______%

The result obtained shall be reported as the percentage of binder content in the mix to the nearest second decimal.

Read More:
Different Types of Bitumen, their Properties and Uses
Asphalt, Bitumen, and Tar – Types, Difference, and Comparison
Types of Bitumen Mixes for Pavement Construction and their Applications