Interface Transformation Behavior of Bonding/Lubrication of Aggregate-Asphalt System

Abstract

Asphalt binder is very sensitive to temperature and exhibits bonding or lubrication effects at different temperatures. The bonding/lubrication properties of asphalt affect the mixing, compaction, and service performance of asphalt mixture. To analyze the interface bonding/lubrication transformation behavior of aggregate-asphalt systems, the contact-slip test was conducted at different temperatures using a self-developed tester. The maximum slip force was used to evaluate the contact properties of aggregate-asphalt systems. A relational model between the maximum slip force and the temperature was established, and the asphalt content for maximum bonding was proposed. The temperature transition behavior from bonding to lubrication of asphalt was analyzed and delimited, and the critical transition temperature was determined. Test results show that the temperature intervals of lower than 90°C, from 90°C to 150°C, and above 150°C represent the bonding zone, bonding–lubrication zone and lubrication zone, respectively, for the AC-13 aggregate-asphalt system. The critical transition temperature of bonding–lubrication is 120°C. Coarse aggregates are more sensitive to the lubrication effect of asphalt; however, the bonding effect affects the particle system more significantly with an increased content of fine aggregates. The structural stability of an aggregate-asphalt system is more sensitive to the bonding part, so the interface strength formed by the coupling of the contact friction effect of the particle system and the bonding and lubrication effect of asphalt increases first and then decreases with increased asphalt content.