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.

Investigation of Aging Processes in Bitumen at the Molecular Level with High-Resolution Fourier-Transform Ion Cyclotron Mass Spectrometry and Two-Dimensional Gas Chromatography Mass Spectrometry

“…Because of the extreme complexity of bitumen, detailed chemical characterization of aging effects is still an analytical challenge, and therefore, chemical analyses are mostly limited to functional group analysis or fractionation in saturates, aromatics, resins, and asphaltenes (SARA fractionation) . With infrared spectroscopy, the formation of carbonyl as well as sulfoxide functions during oxidative aging has been frequently reported in the literature. ,− It was shown that sulfoxides are formed with higher reaction rates than carbonyls, and moreover, a temperature dependence of the oxidation reaction was revealed. ,− SARA fractionation has been used since the 1960s for the chemical description of bitumen . Saturates are considered as almost inert with respect to oxidation, , while resins and asphaltenes show stronger changes. , Petersen et al (2009) ranked the reactivity of the SARA fractions with oxygen in the following order: saturates < aromatics < resins < asphaltenes, while the asphaltene fraction is the most reactive one .…”

Observation of asphalt binder microstructure with ESEM

“…This understanding is especially important due to the changing nature of the way the bitumen is used in pavement (Planche, ). The introduction of Polymer Modified Asphalt (PMA) (Yu et al ., ), Reclaimed Asphalt Pavement (RAP) that incorporates aged binder (Baghaee Moghaddam & Baaj, ), and the development of biosourced agents as both additives (Mikhailenko et al ., ) and standalone binders (Fini et al ., ), means that empirical approaches to asphalt binder in pavement are no longer always viable. Other possibilities are the further understanding of the asphalt binder aging – both field and laboratory simulated – as well as the effects of cold temperature, and of various heating methods.…”

Comparison of Chemical and Microstructural Properties of Virgin and Reclaimed Asphalt Pavement Binders and Their Saturate, Aromatic, Resin, and Asphaltene Fractions

“…The peaks around 1460 and 1376 cm −1 are for aliphatic C−CH 3 groups, serving as baselines for the analysis, because they change relatively little during aging. 23 2.2.2. ESEM Analysis.…”