ABSTRACT
To investigate the effect of aggregate contact condition on the deformation stability of asphalt mixture (DSAM), computed tomography system was used to acquire a contact parameter of aggregates – the aggregate contact index (ACI) characterising the contact characteristic for coarse aggregate. The aggregate slip tests were conducted under different test conditions . This paper investigates the relationship between ACI and slip energy index (SEI), and discusses the effects of aggregate-asphalt combined action and aggregate gradation on DSAM. The results indicate that SEI shows a good relationship with ACI. At 60 °C, SEI has the best linear correlation with the parameter ACI*VFA (Voids Filled with Asphalt), and the deformation stability has the biggest increase amplitude with the increase in ACI*VFA. In the high-temperature range (higher than 50 °C), there is a good linear relationship between SEI and ACI/VFA, and the contribution of aggregate contact to DSAM is bigger under a higher temperature. However, the action of asphalt changes to lubrication from cementation with the increase in temperature, so the growth of SEI with ACI/VFA becomes smaller. AC-13b mix has a better deformation stability than AC-13a and AC-13c mixes at 60 °C though they have the same nominal maximum aggregate size.