Microscopic studies of binder blending on laboratory recycled asphalt mix

Abstract

ABSTRACT During blending between the binders in hot mix recycling, two physical processes occur, namely blending due to diffusion and blending due to mechanical agitation. In the present study, an experimental approach is developed to observe these processes directly on the laboratory recycled asphalt mix samples. Atomic Force Microscopy (AFM) and Confocal Laser Scanning Microscopy (CLSM) are used as the probing tools. The binder concentration profile is estimated at different locations around the reclaimed asphalt pavement material (RAPM) aggregate. Diffusion is observed to be predominant in some of these locations, while, in some other locations, mechanical mixing is observed to be predominant. Assuming that pure Fickian diffusion is happening at those diffusion-spots, the coefficient of diffusion is estimated from the concentration profile at those locations. It is envisaged that the proposed approach would provide a microscopic perspective of the extent of blending during the recycling process.