Gradation Design of the Aggregate Skeleton in Asphalt Mixture

Abstract

Rutting is one of primary distresses in asphalt pavements. The asphalt mixtures with strong aggregate skeleton have a good rutting resistance. The gradation design method of coarse aggregate skeleton and asphalt mixture was studied. A three-dimensional spheroid model was used to analyze the mechanical characteristics of the aggregate skeleton. The aggregate crushing test and the Marshall compact test were conducted to verify the theoretical analysis. The results show that the stability of aggregate skeleton was improved by increasing the number of contact points. And a gradation design model was developed for the coarse aggregate skeleton. 4.75 mm was defined as the dividing size between coarse and fine aggregates. The asphalt content and performance-related volume parameters were introduced into the design method. It ensures the aggregate skeleton formation and the desired performance of asphalt mixtures. The aggregate gradation is very similar to that of SMA, and that the designed asphalt mixture has good high-temperature performance. It is concluded that the proposed design method a have good practical applicability.