Viscosity Test: - Viscosity is defined
as inverse of fluidity. Viscosity thus defines the fluid property of bituminous
material. Viscosity is the general term for consistency and it is measure of
resistance to flow.
Apparatus: - Tar viscometer with
4mm and 10mm orifices – The apparatus consist of main parts like cup, valve,
water bath, stirrer, receiver and thermometers etc.
Procedure: - The tar cup is
properly leveled and water in the bath is heated to the temperature specified
for the test and is maintained throughout the test. Stirring is also continued.
The sample material is heated at the temperature 200 C above the
specified test temperature, and the material is allowed to cool. During this
the material is continuously, stirred. When material reaches slightly above
test temperature, the same is poured in the tar cup, until the leveling peg on
the valve rod is just immersed. In the graduated receiver (cylinder), 25ml of
mineral oil or one percent by weight solution of soft soap is poured. The
receiver is placed under the orifice. When the sample material reaches the
specified testing temperature within ±0.10C and is maintained for 5
minutes, the valve is opened. The stopwatch is started, when cylinder records
25ml. the time is recorded for flow up to a mark of 75ml. (i.e, 50ml of test
sample to flow through the orifice).
.jpg)
.jpg&description=Viscosity Test: - ){kind=link}