Using discrete element models to track movement of coarse aggregates during compaction of asphalt mixture

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Department of Civil, Environmental, and Geospatial Engineering


The objective of this study is to analyze the movement characteristic of differently-shaped compositions in the Superpave Gyratory Compactor (SGC) test through tracking coarse aggregates and the numerical simulation of Discrete Element Method (DEM). First, the coarse aggregates were classified into five shape types (rounded, fractured, angular, elongated and flat) and scanned by a 3D scanner. Second, seven groups of asphalt mixtures with different combination types of hybrid, 100%fractured, 100%angular, 80%fractured + 20%rounded, 60%fractured + 40%rounded, 80%fractured + 20%elongated, and 80%fractured + 20%flat groups were simulated by Particle Flow Code (PFC) Version 5. Third, numerical simulations were conducted to analyze the SGC test process and the movement paths of differently-shaped coarse aggregates were obtained. Finally, statistical analysis on the results from the modeling test were used to study the movement characteristics of asphalt mixtures with differently-shaped aggregate compositions. Through this study, it was found that: (1) there were three main stages of particle movement in the SGC test; (2) the ratio of vertical displacement was obviously larger than that of horizontal displacement, while the variation of vertical rotation was obviously smaller than that of horizontal rotation in asphalt mixtures with differently-shaped compositions; (3) the rounded, elongated and flat coarse aggregates have greater influence on horizontal displacement compared with vertical displacement, but have adverse effects on particle rotations during the compaction process; (4) the effects of elongated coarse aggregates on particle movement were larger than those of flat coarse aggregates, but the flat coarse aggregates have more influence on particle rotation for the variations of horizontal and vertical rotational angles.

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Construction and Building Materials