Bitumen

The bitumen we use in our roads and buildings is refined from carefully selected crude oils. A variety of different refining methods produce different kinds of bitumen and allow the manufacturer to produce specific characteristics in the bitumen. Producers often blend multiple crude oils together to produce consistent, high-quality bitumen that meets precise engineering specifications. (Source: Eurobitume website)

• Hard bitumen for use in road construction
• Cutback bitumen – a blend of bitumens with solvents such as kerosene
• Emulsions – stable solutions of bitumen in water
• Polymer-modified bitumens – mixtures of special bitumens with polymers such as thermoplastics or elastomers

Rheology

Rheology is the study of flow and deformation of materials under applied forces. Many asphalt binder and bitumen exhibit complex rheological properties, whose viscosity and viscoelasticity can vary depending upon the external conditions applied, such as stress, strain, timescale and temperature.

Softening temperature

Softening point determination by the ring-and-ball method is intended to evaluate the behavior of bituminous binders at elevated temperatures of use. The essence of the ring-and-ball method is that a small metal ball is pressed against a bitumen sample, piercing it to 25 mm with the temperature increased.

Cone penetration

The penetration depth of a bitumen sample with a standardized cone and a defined gravity force determine the hardness and the average service temperature. The cone penetration value is also used for the designation of a bitumen sort.

Stretchability under force and elastic force work

The stretchability (ductility) of a bitumen sample describes the ability of the bitumen to stretch into a thin thread at a constant rate in a water bath at 25 °C. The recorded value of the force is used for the qualitative distinction between unmodified bitumen and polymer-modified bitumen.