Internal structure analysis of asphalt mixes to improve the simulation of superpave gyratory compaction to field conditions

The ability of the Superpave gyratory compactor (SGC) was evaluated to simulate the internal structure of asphalt pavements, and the effect of different field compaction patterns on the produced internal structure. The internal structure distribution was captured and quantified using computer automated image analysis techniques and X-ray computed tomography. The different field compaction patterns produced similar internal structure in asphalt pavements. However, changing the compaction variables in the SGC (angle, pressure, height, and temperature) affected the internal structure in laboratory specimens. The internal structure of asphalt pavements could be simulated by changing the angle of gyration and specimen height in the SGC. Increasing the temperature of base plates and mold of the gyratory compactor assisted in developing more random distribution of air voids within a specimen. Field cores had similar air void distribution patterns irrespective of the compaction procedure. The highest percent air voids was at the top and decreased with depth until about one third of a core thickness after which it attained a relatively uniform value. There was no difference in air void distribution in the horizontal direction. Different field compaction patterns did not induce differences in the aggregate structure distributions of asphalt pavements.