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This test is done to determine the bitumen content as per ASTM 2172. The apparatus needed to determine bitumen content are –
i) Centrifuge extractor
ii) Miscellaneous – bowl, filter paper, balance and commercial benzene.
A sample of 500g is taken.
Procedure to determine bitumen content
i) If the mixture is not soft enough to separate with a trowel,place 1000g of it in a large pan and warm upto 100oC to separate the particles of the mixture uniformly.
ii) Place the sample (Weight ‘A’) in the centrifuge extractor. Cover the sample with benzene, put the filter paper on it with the cover plate tightly fitted on the bowl.
iii) Start the centrifuge extractor, revolving slowly and gradually increase the speed until the solvent ceases to flow from the outlet.
iv) Allow the centrifuge extractor to stop. Add 200ml benzene and repeat the procedure.
v) Repeat the procedure at least thrice, so that the extract is clear and not darker than the light straw colour and record the volume of total extract in the graduated vessel.
vi) Remove the filter paper from the bowl and dry in the oven at 110 + 5oC. After 24hours, take the weight of the extracted sample (Weight ‘B’).
REPORTING OF RESULTS
Bitumen content = [(A-B)/B]×100 %
Repeat the test thrice and average the results.
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