Microstructure Index of Hot Mix Asphalt

Digital image processing technique is used to quantify the impact of aggregate gradation and compaction method on air voids distribution and aggregate orientation and distribution. The air voids distribution was found to be sensitive to water permeability than traditional volume indexes. A more orizontal orientation was found for the aggregate particles compacted in the Superpave gyratory compactor. On the other hand, aggregate particles appear to have more of a random distribution in vibratory compactor samples. Aggregate distribution was found to be sensitive to the aggregate gradation and type of compaction. Base on digital image process technique, analyze the microstructure of hot mix asphalt, and present a series of microstructure parameters including the air voids distribution, aggregate distribution and major axis angle distribution. The result illustrate that the microstructure indexes can evaluate the internal structure difference of hot mix asphalt.