Research Project SRV

As part of this project, an interlaboratory study of two DSR test methods for characterising the low-temperature behaviour of bitumen was designed, coordinated, evaluated and published: the shear relaxation test (SRV) using an 8 mm parallel-plate test geometry at −10 °C, and the temperature-frequency sweep (T-f sweep) using a 4 mm parallel-plate test geometry in the temperature range from 0 to −30 °C. Seventeen laboratories, with a total of 20 testing instruments from two manufacturers, took part in the interlaboratory comparison carried out in 2023.

According to current findings, the comparability of the shear relaxation viscosity proved to be independent of the testing instrument used, whilst the relaxation behaviour, particularly in the case of hard binders, was influenced by instrument-specific control differences. In the temperature-frequency sweep, very low test frequencies (< 0.1 Hz) in particular showed high variability and are therefore not recommended for future investigations.

The results show that both methods are fundamentally reliable and exhibit good repeatability within a single laboratory. The comparability of results between different laboratories is currently still limited. The differences cannot be explicitly attributed to a particular equipment manufacturer, but rather to specific testing laboratories.

Overall, however, the results confirm the potential of both test methods for meaningful binder characterisation.

Funding: Forschungsgesellschaft für Straßen- und Verkehrswesen (FGSV)

Titel: Konzeption, Auswertung und Ergebnisverwertung einer Vergleichsuntersuchung zur rheologischen Prüfung von Bitumen bei niedrigen Temperaturen

Acronym: SRV (for Scherrelaxationsversuch, Shear Relaxation Test)

Projekt Duration: 16 month (01. February 2025 – 30. May 2026)

Project partner: Technische Universität Braunschweig, Institut für Straßenwesen (ISBS)  und Ruhr-Universität Bochum, Lehrstuhl für Verkehrswegebau (LVW)

Results:

Final Report

Appendix A – Quick Guide: 4 mm Temperature-Frequency Sweep

Appendix B – Quick Guide: Shear Relaxation Test (SRV)

Appendix C – Comprehensive Report on the Comparative Study

Appendix D – Research Summary: TRB Conference, January 2026, Washington

Appendix E – Scientific Poster: TRB Conference, January 2026, Washington

Appendix F – Research article in the International Journal of Road Materials and Pavement Design (RMPD) (Open Access)

Appendix G – Article for German journal Straße und Autobahn (to be published in September 2026)

Appendix H – Draft of TP Bitumen, Part 2 C (T-f-Sweep)

Appendix I – Draft of AL SRV (Shear Relaxation Test)