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This test is done to determine the specific gravity of semi-solid bitumen road tars, creosote and anthracene oil as per IS: 1202 – 1978. The principle is that it is the ratio of mass of a given volume of bitumen to the mass of an equal volume of water, both taken at a recorded/specified temperature.
The apparatus needed to determine specific gravity of bitumen is
i) Specific gravity bottles of 50ml capacity
ii) Water bath
iii) Bath thermometer – Range 0 to 44oC, Graduation 0.2oC
Take the sample (half the volume of the specific gravity bottles).
Procedure to determine specific gravity of bitumen
i) Clean, dry and weigh the specific gravity bottle along with the stopper (Weight ‘A’).
ii) Fill the specific gravity bottle with freshly boiled distilled water and insert the stopper firmly. Keep it in the water bath having a temperature of 27.0 + 1oC for not less than half an hour and weigh it (Weight ‘B’).
iii) Weigh the specific gravity bottle about half-filled with the material (Weight ‘C’).
iv) Weigh the specific gravity bottle about half-filled with the material and the other half with distilled water (Weight ‘D’).
v) Weigh the specific gravity bottle completely filled with the material (Weight ‘E’).
REPORTING OF RESULTS
i) Specific gravity (Solids and semi-solids) = (C-A )/[ ( B-A) – (D-C)]
ii) Specific gravity (Liquids) = (E-A)/(B-A)
The average of the two results should be reported.