Quantitative evaluation of asphalt blending characteristics in epoxy‐modified hot recycled asphalt mixtures based on 3D confocal fluorescence technology

Abstract

AbstractThis study proposes a novel method to quantitatively evaluate the blending effect between aged asphalt and epoxy asphalt in epoxy asphalt‐modified hot recycled asphalt mixture, based on three‐dimensional confocal fluorescence microscopy technology. Samples of epoxy asphalt‐modified hot recycled asphalt mixtures were prepared in a laboratory using new aggregates, epoxy asphalt, and reclaimed asphalt pavement materials that were simulated in the laboratory by subjecting new asphalt mixtures to a short‐term and long‐term aging process. Cube‐shaped stone aggregates were designed to distinguish between new aggregates and reclaimed aggregates. The distribution of epoxy resin in the epoxy asphalt‐modified hot recycled mixtures was tracked using a laser scanning confocal microscope. To address the depth attenuation issue caused by light absorption and scattering, as well as the overall intensity differences resulting from field depth differences and attenuation morphology, a depth compensation function and a feature weight allocation method were proposed. Results from the above method indicated that the degree of blending (DoB) ranged from 65% to 75% on the surface of new aggregates but from 45% to 70% on the surface of reclaimed aggregates. Most of the old asphalt still adhered to the surface of reclaimed aggregates after migration. The proportion of epoxy asphalt in the outer layer of asphalt film on new aggregates is higher than that on reclaimed aggregates. The DoB between the asphalt binders significantly decreased as the aging degree increased. Increasing the epoxy content reduced the viscosity of the epoxy asphalt and effectively improved the DoB between the new and old asphalt binders.