Two-dimensional Morphology Characterization on Recycled Coarse Aggregate

Abstract

Recycled asphalt mixture is a complex multi-phase structure consisted of a variety of materials; and the aggregate came from the following two sources: recycled asphalt mixture and new aggregate. Upon the impact of traffic load and external environment, the particle size of the former is refined in different degrees, resulting in geometry changes and further effects on the skeleton structure of recycled asphalt mixture and the interaction in aggregate asphalt. Taking the aggregate asphalt recycled from Chongqing-Changshou Highway as sample, two-dimensional morphological structures of recycled and new aggregate were compared and analyzed through image forming technology in this paper. And parameters of ovality and shape factor were involved in analyzing the variation of two-dimensional morphological characteristics as well as the variation of two-dimensional morphological characteristics of recycled aggregate composed of old and new aggregate in different mixing ratios. The results showed that as particle size increased, ovality gradually decreased, ovality of recycled aggregate and new aggregate had little changes, shape factors of recycled granite, new limestone, and new granite decreased gradually; when particle size were the same, shape factor of recycled aggregate was the smallest. Through analyzing the morphological structure of aggregate, the mixing amount of recycled aggregate had little effect on the variation of shape factor and ovality difference of recycled aggregate, indicating that the mixing ratio of recycled aggregate was unrestricted.