13.03.2023 by Claire Strasser
No Cracks, No Ruts – How Asphalt Should Behave
Road pavements must withstand different types of StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress over a long period of time, such as temperature gradients that can exceed 50°C, dependent on the region of the world. They also must absorb high loads from cars and trucks.
Asphalt binder is one of the most important components of pavements. Its chemical composition and rheological properties are crucial for the performance of pavements, i.e., their ability to withstand the challenges they face without cracking or rutting.
The behavior of asphalt is closely related to its viscoelastic properties, which can be determined with rheological tests, among others by means of oscillation measurements.
Very Long Measurement Time? Create a Master Curve!
The wider the frequency range of an oscillation test, the more information the user gets about his product. In particular, very low frequencies are associated with very long time scales. These help predict the behavior of the asphalt for years to come. However, this very low frequency range cannot be measured directly, as this would require weeks of experiments.
This is where Time-Temperature Superposition comes into play: A shift in temperature has the same impact on the viscoelastic properties as a shift in frequency. In other words, you can expand the frequency range of a measurement by performing tests at different temperatures. The result is a master curve that describes the viscoelastic properties from very low to very high frequencies.
For more information on this topic, please see our latest application note:
By the way: How to create a master curve is also explained in this video: