In this study, a new empirical approach was developed to evaluate changes in asphalt concrete microstructure under full-scale accelerated pavement test loading with a Heavy Vehicle Simulator (HVS) of composite pavement. The approach compared X-ray computed tomography (CT) images taken before and after HVS rut testing. Results were used to identify the differences in the movement of aggregate and changes in air-void content and distribution occurring during rutting accumulation of rubberized gap graded and polymer modified dense graded mixes for two overlay thicknesses (64 and 114 mm).

 
Particle movement (displacement vectors) under full-scale trafficking. Digital Image Correlation (DIC) method is used for particle tracking. 
Left half of the block was loaded. Material is sheared to the sides of the load.
 
  

 
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