Micro-structural characteristics of asphalt mixture and its effect to mechanical performance based on two-stage mixing method

Abstract

Conventional asphalt mixtures are prone to material separation during mixing, causing rutting, loosening, and cracking of the pavement. This study proposes a two-stage mixing method to address these problems. The theoretical asphalt film thickness is calculated, and a physical index of the mixture for aggregates with different specific surface areas is used to determine the optimal asphalt mixing ratio. The microstructural characteristics and mechanical properties of the mixtures are evaluated using digital image processing, laboratory experiments, and correlation analyses. The results show that the two-stage mixing process mixes the aggregate more thoroughly, resulting in a uniform asphalt film with sufficient contact between the asphalt particles, improving the mixture’s mechanical performance. The results of this study can be used to improve the design of asphalt mixtures and reduce the use of petroleum asphalt.