Evaluation of the effect of aging on mechanical and fatigue properties of sand asphalt mixtures

This paper investigates the effect of oxidative aging of asphalt binders on their material characteristics and fatigue fracture properties during controlled-strain, dynamic mechanical testing. Cylindrical sand asphalt samples were fabricated with an unaged and two aged binders at different levels of aging. Various dynamic mechanical tests (strain sweep, frequency sweep, and time sweep) were performed to estimate viscoelastic characteristics and fatigue behavior. Test results and mechanical analyses conclude that the oxidative aging clearly increased elastic characteristics and reduced stress relaxation capability of asphalt binders. Furthermore, the aging has impact on the changes of thermo-viscoelastic properties. Due to the increasing brittleness and less viscous damping ability, the aged mixtures approached fatigue failure faster than the unaged mixtures and did not show any significant microdamage healing effects. Dynamic mechanical testing results showed good agreements with surface energy measurements that are well-known indicators representing fracture and healing potential of asphalt binders.