Microscopic investigation on blending of montmorillonite modified bitumen and reclaimed asphalt binder

Abstract

The performance of asphalt mixtures containing reclaimed asphalt pavement (RAP) are strongly influenced by the degree of blending between RAP and virgin bitumen. In the aim of revealing the blending interface, the present work reports an experimental investigation on the blending degree between modified bitumen and RAP (or aged bitumen). A montmorillonite-rhodamine composite modifier was prepared as a tracer, which has exclusive element and fluorescence. Using microscopic test technique, the blending process of and the crack process of RAP bitumen was observed, and the blending image of new reclaimed asphalt mixture was obtained. The interface was investigated through image processing and machine learning. Based on the results, the montmorillonite modifier slightly affected on the softening point and penetration of virgin bitumen after addition. The blending interface was engagement like gears. The optimal heating temperature range is 110 °C to 115 °C for forming a better adhesive interface between RAP and modified bitumen. Moreover, the interface transition zone thickness between RAP and modified bitumen was measured to be 4 to 8 μm.