Long?term performance of hot mix asphalt (HMA) pavements is significantly influenced by the internal structure characteristics related to the aggregate skeleton. The type and degree of compaction is very important for internal packing and generation of the aggregate skeleton in HMA pavements. However, direct quantification of aggregate packing in HMA in 3D has not been successfully accomplished. One method to quantify 3D microstructures is through experimental and imaging techniques (e.g. X?ray Computed Tomography), which is usually very costly and time consuming. On the other hand, generating digital specimens through 3D numerical packing/compaction simulations using the real aggregate shapes may be an efficient and economical alternative. This paper presents a realistic 3D packing/compaction model that utilizes real 3D shapes of aggregates. The model is based on one of the most efficient particle?based simulation techniques called "Dissipative Particle Dynamics (DPD)". The primary advantage of DPD is that the movement of arbitrarily shaped aggregates (during compaction) can be simulated realistically. In this paper, a modified version of DPD model (called MDPD) was developed to better represent the micromechanical behavior of HMA. The model was compared against laboratory tests, and a very good agreement was observed.