Determination of Binder Content of Asphalt Mix Experiment

Objective

To determine the binder content in a given bitumen mix by cold solvent extraction method

IS Standards used:IS 13826-7(1993)

Apparatus Required:

1. Centrifuge
2. Balance of capacity 500 gram and sensitivity 0.01grams.
3. Thermostatically controlled oven with capacity up to 2500C.
4. Beaker for collecting extracted material

Experimental procedure:

1. Take exactly 500 grams of representative sample and place in the bowl of 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 (F₁).
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. Run the centrifuge until the bitumen and benzene are drained out completely.
9. Stop the machine, remove the cover and add 200 ml of benzene to the material in the extraction bowl and the extraction is done in the same process as described above.
10. Repeat the same process not less than three times till the extraction is clear and not darker than a light straw colour.
11. 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 105°C to 110°C and cool to room temperature.
12. Weigh the material (W₂) and the filter paper (F₂) separately to an accuracy of 0.01grams.

Calculations

Weight of sample taken (W ₁) =

Weight of sample after extration taken (W ₂) =

Increased weight of filter paper (W₃) = F₂- F₁ =

Percentage of binder in the total mix = W₁-(W₂ + W₃)/W₁ x 100

General remarks:

Viva Questions:

1. What is the criteria for specifying benzene as solvents to be used in the test?
2. How would the road surface be effected in case the test reveals use of
• Lesser quantity of bitumen?
• More quantity of bitumen than the optimum quantity?