Using electromagnetic radiation for producing reclaimed asphalt pavement (RAP) Mixtures: Mechanical, induced heating, and sustainability assessments

Abstract

This research investigates feasibility of using electromagnetic-based method to produce reclaimed asphalt pavement (RAP) mixtures. The conventional heating process in dryers of asphalt plants considerably over ages and diminishes mechanical properties of high RAP asphalt mixtures. In addition, the RAP asphalt plants (i.e., parallel flow, counter flow, and double barrel) have critical drawbacks in producing high RAP asphalt mixtures, such as partial activation of asphalt binder in RAP, non-uniform diffusion between virgin binder-rejuvenator-RAP binder, over aging of RAP aggregates, and high fossil fuels consumption, leading to mechanical, environmental, and economic consequences. Recently, the electromagnetic-based approaches (e.g., microwave radiation) were utilized in pavement industry for the diverse applications, including micro-crack healing and de-icing purposes. In this study, the capability of microwave for heating and preparing RAP mixture, containing different WEO amounts as rejuvenator, was investigated. The fracture properties at intermediate and low temperatures and moisture susceptibility of asphalt mixtures comprised of 80 and 100% RAP prepared using electromagnetic radiation were determined and compared against the mixtures made of traditional draft oven. Besides, effect of different WEO contents, as rejuvenator, were investigated. According to the results, heating of RAP aggregates using electromagnetic radiation as well as addition of WEO can remarkably enhance cracking resistance of asphalt mixtures. Moreover, the sustainability aspects of the suggested approach to prepare the RAP mixtures were compared against the conventional method considering energy consumption, equivalent CO2 emission, and cost values. The gray rational analysis (GRA) was conducted to rank the mixtures according to mechanical and sustainability aspects. The results reveal that utilization of electromagnetic radiation in producing high RAP asphalt mixtures can substantially improve sustainability aspects of RAP asphalt mixture.