The quality and strength of bitumen have been determined by the penetration test, flash and fire point test, and softening point test. Now the bitumen extraction test is conducted to find the quantity of bitumen used in bituminous concrete in percentage.

What is a Bitumen Extraction Test?

The test used to determine the bitumen binder usage in the asphaltic pavement by cold dissolver method as per ASTM D 2172 is known as a bitumen extraction test.

A particular piece of bitumen sample shall be collected after completion of pavement work and tested to find out the quality of the bitumen binder.

Why is it required?

The quality, durability, and strength of the asphaltic pavement depend upon the percentage of bitumen used. So it is necessary to determine the value to check the quality of the pavement.

Apparatus 

bitumen extraction test apparatus

  • Centrifuge Extractor
  • Beaker
  • Weighing Machine
  • Oven
  • 500 g bitumen sample
  • Filter paper

Test Procedure

  • Weigh 500g bitumen sample (W1) and place the sample in the cup of the centrifuge.
  • Weigh the filter paper and note it as (F1)
  •  Fill the benzene (dissolver) into the cup up to the sample top (as thoroughly soaked).
  • The benzene will separate the aggregates and bitumen.
  • Now place the filter paper and cover the sample in the centrifuge apparatus.
  • Now place the beaker at the outlet of the centrifuge to collect the extracted sample. 
  • Leave up to 1 hour for the solvent to dissolve the bitumen and other ingredients of asphaltic pavement.
  • Now start the centrifuge machine and increase the speed gradually to 3600 revolutions per minute. 
  • The bitumen and benzene will completely drain out in the beaker. Now again, add more benzene into the cup and again start the same process.
  • Run the centrifuge again and again until the bitumen extraction is completed. The extracted material seems to light straw colour.
  • Weigh the extracted material as W2.
  • Now remove the filter paper and dry it through the oven at the temperature range of 1050°C to 1100°C and allow it to cool to room temperature.
  • Finally, weigh the dried filter paper as F2.

The test should be conducted at least three samples, and the average value is the percentage of bitumen used in the pavement. 

Lab Report

SI Description Sample 1 Sample 2 Sample 3
1 Weight of mixture sample (W1)
2 Weight of filter paper before extraction (F1)
3 Weight of mixture after extraction (W2)
4 Weight of filter paper after extraction (F2)
5 Weight of filler collected in filter paper (F1-F2) =W3

Calculation

The percentage of bitumen = (W1-(W2+W3)/W1) x 100

Video Illustration

Video Courtesy – HIGHWAY GUIDE

Happy Learning 🙂

Author

Satheesh is a Civil Engineer who has more than 9+ Years of experience in residential construction. He is the author, editor of Civil Planets

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