Temperature Control Unit Shrp - Thermo Scientific HAAKE RotoVisco 1 Instruction Manual

Temperature Control Units

11.8 Temperature control unit SHRP

Rheometer like HAAKE RheoStress with parallel plate sensor
systems are suitable for the rheological testing of viscous and
elastic behavior of bitumen and asphalt blends which are used
as surfacing at road building. The rheological tests are usually
used for more or less solid bitumen samples in the tempera-
ture range from about 5C to 85C .The samples are most of
the time tested in the dynamic mode which subjects disk--like
17 specimens placed into the gap between parallel plates -- alter-
natively a gap between an upper cone and a lower plate is pos-
sible, but rarely used for bitumen -- to a sinusoidal stress. The
resulting response of the sample --a sinusoidal deformation--is
measured in the form of the complex modulus G* related to the
resistance of the mass against a sinusoidal deformation and
the phase shift angle "" which appears between the applied
stress and the resulting strain. Making use of the angle "" the
complex modulus G* can be broken up into the components
G' -- the storage modulus defining the elastic component -- and
G'' -- the loss modulus defining the viscous component in the
rheological behavior of a sample subjected to such a dynamic
test. The phase angle "" defines the ratio of the two moduli.
From the dynamic measurements with special sensor sys-
tem for SHRP tests which are described in detail below tests
of the viscosity of bitumen melts at temperatures of 120C to
180C have to be distinguished. For these measurements
sensor systems with a measuring gap between coaxial cylin-
ders for the HAAKE rheometers named above are used. At
these melt tests the shear stress in proportion to the viscosity
of the sample is measured at given shear rate.
Bitumen and asphalt compounds are very sensitive to tem-
perature variations in their rheological behavior., i.e. in their
viscoelastic response to applied loads and stresses. When
subjecting them in a DSR--rheometer to dynamic or to
creep and recovery tests this testing should be carried out
in a wide temperature range that relates to summer/winter
road pavement conditions. According to the American
SHRP specifications measurements at temperatures of
0C to 85C are desirable.
At low temperatures the materials are tested for the likeli-
hood of cracks as the result of a short and hard deformation
of the more or less hard and brittle material. Under these
conditions the road material may just split/crack unless it is
sufficiently elastic to absorb temporarily sudden loads.
At low temperatures the bitumen may also creep -- flow very
slowly -- even as the result of much lower but longer lasting
stresses such as caused by the pressure of car tires when
the automobiles have to stop e.g. in front of red traffic lights.
It is important to test such samples also at temperatures up
70