Contribution of the Creep-Recovery Test to the Evaluation of Bituminous Mixes Aging

Once in service, pavements are exposed to a variety of mechanical and climatic stresses, leading to changes in their mechanical properties and increasing deterioration. Aging is among the most common causes of hardening of bituminous pavements, causing premature deterioration. The aim of this study is to assess the effect of laboratory aging on the linear viscoelastic properties of asphalt mixtures. Therefore, three thermo-oxidative aging durations (0, 4, and 9 days) were considered. To simulate the long-term thermo-oxidative aging of binders, RTFOT and PAV tests were conducted on fresh bitumen, followed by physicochemical characterizations (FTIR and asphaltene content) at different aging periods. Complex modulus and creep-recovery tests were also performed on aged and unaged bituminous mixtures. The findings show that the stiffness moduli of mixes increase with the duration of long-term thermo-oxidative aging. The evolution of axial strain under creep-recovery conditions provides an interesting relationship between steady-state creep viscosity η0 and physicochemical parameters, reflected by a decrease in creep compliance with aging duration and a good correlation between η0 and carbonyl IC=O and sulfoxide IS=O indices.