Enhancement mechanism of induction heating on blending efficiency of RAP - virgin asphalt in steel slag recycled asphalt mixtures

Reusing reclaimed asphalt pavement (RAP) contributes to the sustainable development of road engineering, making a cleaner pavement construction. While limitation to the extension and application of recycled asphalt mixtures lies in lower and unclear blending efficiency for RAP asphalt and virgin asphalt. Previous studies have indicated that steel slag as aggregate for asphalt mixtures can improve the induced healing efficiencies. This study is designed to explore induction heating on blending efficiency and interaction mechanism of RAP asphalt and virgin asphalt in steel slag recycled asphalt mixtures. Induction heating technique and staged extraction method were combined to obtain different blending layers asphalt. Dynamic Shear Rheometer (DSR), infrared spectroscopy, TLC-FID and Gel Permeation Chromatography (GPC) were applied to investigate its rheological properties, molecular structures, four components contents and molecular weight distribution, respectively. The results indicate that asphalt layered system with non-homogenous blending efficiency occurs throughout all layers of the mixtures. Induction heating is conducive to the decrease of flow activation energy and improvement of blending degree of asphalt layer. It demonstrates a significant promotion effect on reduction of the carbonyl index and sulfoxide index of blend asphalt layer. Colloidal instability index, average molecular weight and polydispersity of asphalt layer all decrease after induction heating, indicating that induction heating can effectively enhance blending efficiency of RAP asphalt and virgin asphalt for recycled asphalt mixtures. (C) 2020 Elsevier Ltd. All rights reserved.