Research on evolution of structural characteristics of force chain network during asphalt mixture compaction process

The force chain network is the main carrier for asphalt mixture to bear load and transfer load. Compaction is the key phase when the force chain network is developed. The purpose of this research is to investigate the evolution of the force chain network structure of asphalt mixtures during compaction. Firstly, a virtual aggregate library of real morphology was established based on a 3D blue light scanner. Secondly, the simulation model of gyratory compaction of SMA-13 and OGFC-13 asphalt mixtures was established by the Discrete Element Method (DEM). Thirdly, the force chain network during compaction was analyzed by aggregate contact information and complex network theory. The results showed that the distribution of different types of contact pairs in SMA-13 was relatively uniform, and a large number of coarse contact pairs (13.2–9.5, 13.2–4.75 and 13.2–2.36) in OGFC-13 were the important reason for the formation of large void structure. As compaction degree increased, the degree and strength of aggregate increased, the proportion of aggregate with degree of zero decreased obviously, and the clustering degree of aggregate increased. The larger the particle size of the aggregate, the greater the strength. The contact force distribution of the small aggregate was more uniform than that of the large aggregate. Compaction can make the contact force distribution between aggregates more uniform, shorten the distance between aggregates in asphalt mixture, and improve load transfer efficiency. Compared to the OGFC-13 mixture, the SMA-13 mixture had a more uniform distribution of contact forces between aggregates and a greater ability to transfer loads.