Thermo Scientific HAAKE RotoVisco 1 Instruction Manual page 76

Temperature Control Units
The temperature of the liquid surrounding the parallel plates
and equally the sample being tested is measured by means
of a temperature sensor placed into the lower measuring
plate from underneath -- not shown in Fig. 1 --. The measured
temperature is displayed on the computer screen during the
measurement and has an accuracy of  0.1C. According to
this actual temperature value of the sensor system the set
value must be corrected at the bath and circulator until the
actual value of the temperature sensor is conform to the re-
quired measuring temperature.
The accuracy of the rheological test data depends heavily on
the temperature accuracy of the thermal liquid provided by
the bath and circulator. In order to maintain a preset temper-
ature level in the tested bitumen specimen of  0.1C as re-
quired by the SHRP standard, the bath and circulator must
guarantee a temperature tolerance of better than or equal to
 0.05 C. The actual temperature of the thermal liquid sur-
rounding the parallel plates and thus the specimen should be
counter checked by means of a calibrated external ther-
mometer graded with a  0.05 C scaling.
Bitumen being characterized by its low thermal conductivity
normally requires some 5 min. to reach any test tempera-
ture. Operators may check the actual time requirement for
reaching a temperature equilibrium by running dynamic
tests in the "time mode", i.e. check how long it takes after
having raised the liquid level above the parallel plates to
reach a time-constant value of i.e. G*.
The specimens placed into the gap between the parallel
plates must be preshaped in a separate work step into suit-
able disks of the right diameter and height prior to their instal-
lation in the gap:
a) diameter of 25 mm and 1 mm thick test disks for tests at
higher test temperatures and for the measuring plate with a
diameter of 25 mm
b) diameter of 8 mm and 2 mm thick disks for tests at lower test
temperatures -- 5C --used in combination with the 8 mm plate.
The tests can be run at different constant test temperatures.
a.) with programmed variable shear stresses in "Controlled
Stress (CS)" mode of the rheometer
b.) alternatively with programmed variable frequency in
"Controlled Strain (CR)" mode of the rheometer.
If tests are to be run according to the SHRP standard the re
quired standards have to be kept. Please see the added
copy of these standards.
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