Identification and analysis of mixing-induced homogeneity in reclaimed asphalt pavement materials

Abstract

Asphalt mixtures were prepared in the laboratory using reclaimed asphalt pavement(RAP)at a 40% mass concentration to investigate the homogeneity characteristics of RAP during the mixing process, taking into account the mixing duration and aging rate. Specifically, titanium dioxide powder was incorporated into RAP binders as an identification tracer. Homogeneity indices were subsequently established to evaluate the homogeneity characteristics of asphalt mixtures. Computed tomography(CT)was used to create digital images of asphalt mixtures, and Mimics software was used to identify the components. Finally, a homogeneity evaluation system was established to assess the uniformity of both the components and RAP agglomerates. The results indicate that homogeneity is mostly influenced by the distribution of coarse aggregates, followed by asphalt binders and air voids. Homogeneity improvement is hindered by the formation of new agglomerates during the mixing process, whereas it is increased by prolonging the mixing time. A homogeneity evaluation system based on components and agglomerates can effectively reveal the principles governing homogeneity characteristics and provide a reference for the construction of high-quality recycled asphalt pavement.

Keywords

reclaimed asphalt pavement(RAP) / mixing-induced homogeneity / image segmentation / homogeneity index