Binder Composition and Intermediate Temperature Cracking Performance of Asphalt Mixtures Containing Recycled Asphalt Shingles

摘要

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 recycled asphalt shingles (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 aging using Fourier Transform Infrared (FTIR) spectroscopy, and fracture resistance of laboratory produced mixtures using the Semi-Circular Bending (SCB) test at intermediate temperature. Molecular fractionation through GPC of RAS samples confirmed the presence of associated asphaltenes in greater concentrations than recycled asphalt pavement (RAP) 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.