Contact: Matthias Staschkiewicz, M.Sc.
In den vergangenen Wintern konnten vermehrt frühzeitige Schäden an Asphaltdeckschichten in Form von Rissbildungen beobachtet werden. Auffällig hierbei ist allerdings, dass evtl. nicht die Strenge der Winter (absolute Tiefsttemperaturen) Problemursache ist, sondern die Häufigkeiten von Development of a test method for assessing the low-tempIn the past few winters, increased premature damage to asphalt surface courses in the form of cracking has been observed. What is striking here, however, is that it may not be the severity of the winters (absolute low temperatures) that is the cause of the problem, but rather the frequency of freeze/thaw cycles and possibly the number of spreading actions. These are known to lead to crack-inducing tensile stresses in the asphalt surface layer of a road.
As the performance-oriented test methods currently anchored in the various guidelines with regard to cold behaviour require large quantities of binder, they are not suitable for control tests in the event of damage. For this reason, a test method is to be developed in the course of this research project in which the cold behaviour of bituminous binders can be investigated with smaller sample quantities. The focus here is on methods using the dynamic shear rheometer (DSR), which is already used in the investigation of rheological properties in the medium and high temperature range.erature behaviour of bitumen Based on national and international research findings, the following four test methods were incorporated into the research project:
- Cold testing with the 8 mm plate-plate geometry under creep load: shear relaxation test (SRV)
- Cold test with the 4 mm plate-plate geometry (with and without trimming)
- Tensile relaxation test (ZRV)
- Cold test on slim, cylindrical samples: ‘TU Delft method’
Which of these four methods ultimately provides the best characterisation of the cold behaviour is to be determined by means of a staged work programme (initially ten binders for four methods, then a further 40 binders for two selected methods). Finally, a validation with other test methods (BBR, tensile retardation test according to Schellenberg) and through specific binder selection (from cracked asphalts) will take place.
Bundesanstalt für Straßenwesen
FE 07.0293/2017/EGB
Copyright © Lvw 2024
Last update: Nov 04, 2024