Postcarbone road - The endless cycle of asphalt reuse

• Applicants: Professor Dr.-Ing. Martin Radenberg; Professor Dr. Dietmar Stephan; Dr.-Ing. Sandra Weigel
• Subject Area: Construction Material Sciences, Chemistry, Building Physics ; Architecture, Building and Construction History, Construction Research, Sustainable Building Technology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392670763

In all areas of our modern society, crucial ambitions are the efficient use of our resources and optimal sustainability. In road construction, the reuse of asphalt can significantly contribute to achieving these goals, as large quantities of reclaimed asphalt are obtained in Germany. These reclaimed asphalts have already been reused for decades and in increasingly large quantities so that some asphalts are already facing a higher reuse cycle today. Therefore, this project aims to investigate and evaluate the approach of a multiple or endless reuse cycle of asphalt. For this purpose, a collaboration between the specialised partners Ruhr-Universität Bochum, Technische Universität Berlin and Federal Institute for Materials Research and Testing is foreseen so that the consortium can demonstrate comprehensive experience in the characterisation of the chemical and physical properties as well as the ageing and rejuvenation behaviour of bituminous binders and asphalt. The proposed project is primarily based on the predecessor project Post carbon road – the endless cycle of bitumen reuse, which focused on the effects and mechanisms of different rejuvenators on the binder level. According to this previous project, multiple reuse of bitumen is generally possible using bio-based rejuvenators. But after the fourth cycle at the latest, a critical state is achieved making further reuse impossible. These identified limitations shall be eliminated or rather shifted in the proposed project. For this, a modified rejuvenator will be developed for a selected and known bitumen. The effect of this rejuvenator due to multiple ageing and rejuvenation will then be investigated at the binder level (unmodified and modified bitumen) as well as at the mastic and asphalt level. Furthermore, at the asphalt level, the influence of multiple ageing and rejuvenation on the adhesion behaviour as well as the diffusion of the rejuvenator in the aged binder will be investigated in more detail. For the evaluation of the diffusion, the development of two new method based on infrared spectroscopy is planned. For a simplified design of asphalt mixtures with multiple reused reclaimed asphalts, prediction models for different asphalt parameters based on binder or rather mastic parameters will be determined. In general, the results of this proposed project will show a principal approach whether and how a multiple or endless reuse of asphalt can be implemented being relevant for almost all players of the road construction sector.

• DFG Programme: Research Grants