Development of an FEM-DEM Model to Investigate Preliminary Compaction of Asphalt Pavements

Variations in pavement density have been widely monitored and investigated, both in laboratory and in field experiments, since the compaction of pavement is so critical to its long-term performance quality. In contrast to field testing, laboratory tests are simpler to produce but less accurate. Destructive drilled samples are used to conduct field testing; however, they are limited in their ability to assess density information at specific areas. The use of computationally aided approaches, such as the Finite Element Method (FEM) and the Discrete Element Method (DEM), in research involving asphalt mixtures is increasing, since these methods simulate and evaluate the characteristics of asphalt mixtures at macroscopic and microscopic scales. Individual particle behavior at the microscopic level cannot be fully represented using the FEM alone, and the computing cost of utilizing the DEM approach alone is prohibitively high. The objective of this work is to simulate the pre-compaction process by using the coupled FEM-DEM approach. In order to investigate the impact of the asphalt mixtures’ gradation, a dense-graded asphalt mixture (AC 11) and a gap graded asphalt mixture (PA 11) were simulated. Different paving speeds (4, 5, and 6 m/min) were applied on the preliminary compaction model of AC 11 to study the effect of the paving speeds on the compaction process. By comparing the angular velocity, which worked as a reference of compaction quality, it was demonstrated that the grade AC 11 asphalt mixtures performed better in the preliminary compaction process compared to the grade PA 11 asphalt mixtures. Moreover, since it has an effect on compaction, paving speed was carefully monitored and kept within a reasonable range in order to maximize both pavement quality and project efficiency.