Methods for analyzing the chemical mechanisms of bitumen aging and rejuvenation with FTIR spectrometry

Abstract

The recycling of asphalt is a process where old pavement is broken up and used as reclaimed asphalt pavement (RAP) in new asphalt pavement, often with the aid of recycling agents. The goal of asphalt recycling agents is to reintroduce the properties lost in bitumen and asphalt during aging such as penetration, softening point, viscosity, ductility, cohesion and adhesion to aggregate, reducing the performance of asphalt and requiring its replacement. The purpose of this study is to observe the chemistry of bitumen aging and the effects of recycling agents may have in reversing it. Fourier transform infrared spectroscopy (FTIR)-attenuated total reflectance (ATR) was used to analyse the bitumen aging and regeneration in terms of the evolution of carbonyl, sulfoxide and other bands. FTIR-ATR microscopy was used to study the distribution of these bands between the aggregates in order to understand the remobilization of the old asphalt (RAP) by the recycling agents through observing their penetration into the RAP. A method for aging bitumen and mastic in a ventilated oven was developed. An increase in C=O and S=O indices was observed with aging, plateauing after 7d.