Correlative ageing analysis of thermally treated and rejuvenated bitumen and asphalt

While a high content of reclaimed asphalt in road construction is targeted, recycled bitumen has often undergone chemical and physical damages characterized as ageing. This can be counteracted with additives denoted as rejuvenators and by controlling the heating process during mix production. This study investigated the surface and base layers of three asphalt variants with different levels of reclaimed asphalt and rejuvenator. Asphalt samples were heated either through conventional heat conduction or through dielectrical heating using radio waves. Bitumen analyses included Ring-and-Ball, Needle Penetration, Dynamic Shear Rheometry and Fourier-Transform Infrared Spectroscopy while asphalt performance was assessed by Cyclic Indirect Tensile Test. Ageing indicators were derived and correlated quantitatively, revealing high correlation among bitumen analysis results and lower correlation of asphalt analysis results. Some of the test methods explicitly supported the hypothesis that radio wave heating may induce a lower ageing than conventional heating combined with rejuvenation.