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This test is done to determine the softening point of asphaltic bitumen and fluxed native asphalt, road tar, coal tar pitch and blown type bitumen as per IS: 1205 – 1978. The principle behind this test is that softening point is the temperature at which the substance attains a particular degree of softening under specified condition of the test.
The apparatus required for this test :-
i) Ring and ball apparatus
ii) Thermometer – Low Range : -2 to 80oC, Graduation 0.2oC – High Range : 30 to 200oC, Graduation 0.5oC
PREPARATION OF SAMPLE
i) The sample should be just sufficient to fill the ring. The excess sample should be cut off by a knife.
ii) Heat the material between 75 and 100oC. Stir it to remove air bubbles and water, and filter it through IS Sieve 30, if necessary.
iii) Heat the rings and apply glycerine. Fill the material in it and cool it for 30 minutes.
iv) Remove excess material with the help of a warmed, sharp knife.
Procedure to determine Softening Point Of Bitumen
A) Materials of softening point below 80o C:
i) Assemble the apparatus with the rings, thermometer and ball guides in position.
ii) Fill the beaker with boiled distilled water at a temperature 5.0 ± 0.5oC per minute.
iii) With the help of a stirrer, stir the liquid and apply heat to the beaker at a temperature of 5.0 ± 0.5oC per minute.
iv) Apply heat until the material softens and allow the ball to pass through the ring.
v) Record the temperature at which the ball touches the bottom, which is nothing but the softening point of that material.
B) Materials of softening point above 80oC:
The procedure is the same as described above. The only difference is that instead of water, glycerine is used and the starting temperature of the test is 35oC.
REPORTING OF RESULTS
Record the temperature at which the ball touches the bottom.