Binder composition and intermediate temperature cracking performance of asphalt mixtures containing RAS

Abstract

The use of recycled asphalt shingles (RAS) as a partial replacement for petroleum-based virgin asphalt binder has received considerable attention in recent years. The objective of this study is to correlate the molecular structure of asphalt binders of conventional asphalt mixtures as well as of mixtures containing RAS with their cracking potential at intermediate temperature. Laboratory testing evaluated the molecular composition of asphalt binders obtained from asphalt mixtures evaluated in this study using gel permeation chromatography (GPC), extent of ageing using Fourier Transform Infrared spectroscopy, and fracture resistance of laboratory produced mixtures using the Semi-Circular Bending test at intermediate temperature. Molecular fractionation through GPC of RAS samples confirmed the presence of associated asphaltenes in greater concentrations than recycled asphalt pavement samples. High concentrations of high-molecular-weight asphaltenes decrease the fracture resistance of the asphalt mixtures. The use of rejuvenating agents, Cyclogen-L and Hydrogreen, did not reduce the concentration of the highly associated asphaltenes, and thus they failed to improve the cracking resistance of the asphalt mixtures evaluated in this study.

Keywords:

• Hot-mix asphalt
• stone-mastic asphalt
• recycled asphalt shingle
• gel permeation chromatography
• FTIR spectroscopy
• semi circular bend test

Acknowledgements

The research work reported in this paper was sponsored by LADOTD through the Louisiana Transportation Research Center under contract number 12-3B. The authors would like to express their appreciation to all those who provided valuable help in the conduct of this project, in particular to William “Bill” King, Jr, and Gaylon Baumgardner.

Disclosure statement

No potential conflict of interest was reported by the authors.