Investigation on the microstructure of recycled asphalt shingle binder and its blending with virgin bitumen

Abstract

Recycling waste roofing shingles into pavement construction has attracted more attention due to their high content of usable bitumen. Waste roofing shingles have gone through an airblowing process during production and are exposed to severe weather for many years during service life, which yields extremely aged asphalt binder. The difference in nature between virgin binder and binder from recycled asphalt shingle (RAS) has led to concerns over binder blending and compatibility of asphalt paving mixtures containing RAS. Therefore, usage of RAS has been commonly limited to a maximum of 3-5% incorporation. Currently, there is very little information in the literature that has addressed the RAS-virgin binder blending issues. This paper used atomic force microscopy (AFM) to characterise microstructural properties of the selected virgin, post-manufactured RAS and post-consumer RAS (tear-off) binders, as well as the temperature dependence of microstructure in one type of tear-off RAS binder. Meanwhile, the mode of interaction while bringing together virgin and RAS binders, that is, the extent of mixing or blending, was first observed in this study. According to the observations, AFM proved to be capable of differentiating virgin binder from RAS binder in terms of microstructure. The microstructure of tear-off RAS binder was found to be temperature dependent at moderate temperatures, but changed very little between 60°C and 180°C. Virgin binders selected in this study could not blend through an RAS-binder layer of 300 μm within 30 min at 180°C. Based on the observations, RAS binder was found to interact with virgin binder through "mixing" rather than "blending", in a mixing zone of 25-30 μm.

A Synthesis of Computational and Experimental Approaches of Evaluating Chemical, Physical, and Mechanistic Properties of Asphalt Binders

“…Allen et al reported that the dispersed phase (i.e., bee) increased as saturate fractionate in the asphalt increased [28]. e dispersed phase can completely change when a virgin asphalt is mixed with aged asphalt binder from either recycled asphalt pavement or roof shingles; microparticles found in the interfacial zone ranged from 160 nm to 2.07 µm by recent multiple studies [29,30], as presented in Figure 8 [31].…”

Investigating the interaction between asphalt binder and fresh and simulated RAP aggregate

“…Considering the large specific surface area of mineral aggregates in an asphalt mixture, these effects cannot be undermined. Furthermore, with an increasing emphasis on the use of reclaimed asphalt pavement (RAP), there is a renewed interest in better understanding the influence of binder interactions with fresh aggregates and black rock on the properties of the binder and the mixture [10][11][12].…”

Homogeneity and Viscoelastic Behaviour of Bitumen Film in Asphalt Mixtures Containing RAP

“…They consist of the assessment of the chemical properties of mixtures or the analysis of the microstructure of the bitumen film. Direct methods include, among others, FTIR spectrographic, GPC gel chromatography, X-ray spectroscopy or microscopy analysis [ 11 , 12 , 13 , 14 , 15 ]. The second group consists of indirect methods.…”