Performance bitumen testing

In the force ductility test according to DIN EN 13589, a bone-shaped specimen (initial cross-sectional area 100 mm²) is pulled apart at a speed of 50 mm/min. The evaluation is carried out according to DIN EN 13703. The force required during the pull-out process is recorded. From the course of the force during the extraction process, a qualitative distinction can be made between modified and unmodified bitumen. The maximum force occurring at the beginning of the test characterizes the viscosity of the bitumen and correlates well with the results of the penetration test. The further course of the force allows conclusions to be drawn about the type and activity of the polymers used for modification. The area-related deformation work between 200 and 400 mm extension length is used as the requirement value for PmB.

The viscoelastic properties of bituminous binders can be recorded with the DSR test over a wide frequency and temperature range. A 1 mm thick bitumen specimen is subjected to torsional stress between two circular plates (radius 25 mm). The upper plate is rotated sinusoidally back and forth at different frequencies to a specified angle. The required torque is measured. From the angle of rotation and torque, the magnitude of the complex shear modulus |G*| is calculated. The time difference between the time-shifted sinusoidal rotation angle and torque is determined as the phase shift angle δ.
The magnitude of the complex shear modulus describes the stiffness of the binder. The phase shift angle is a characteristic value of viscoelasticity and allows the deformation behavior of the binder to be estimated between purely elastic (δ = 0°) and purely viscous behavior (δ = 90°).
Within the bitumen specification, the complex shear modulus is given for a temperature of 60 °C and a frequency of 1.59 Hz.