Influence of anti-ageing compounds on rheological properties of bitumen

Abstract

The aim of this study was to investigate the effects of different anti-ageing compounds (AACs) on the oxidative stability, rheological and mechanical properties of bitumen. Modified bitumen samples containing six different AAC combinations, with five samples containing Irganox acid (3,5-di-tert-butyl-4-hydoxyphenylpropionic acid), a hindered phenol polymer-based antioxidant, were fabricated and aged under different conditions using a Rolling Thin Film Oven (RTFO) as well as a Pressure Aging Vessel (PAV). The oxidative stabilising performance (anti-ageing) of the AACs was examined using Fourier Transform Infrared (FTIR) Spectroscopy. The effect of the AAC-modified bitumen on different rheological and mechanical properties was investigated - complex viscosity, linear viscoelastic (LVE) properties, fatigue and rutting - using a Dynamic Shear Rheometer (DSR). The results illustrated that all the AAC-combinations examined afforded good oxidative stability to the base bitumen, with outstanding anti-ageing performance achieved by formulations C, D, E and F (Irganox acid:NaMMT, Irganox acid:furfural without or with DLTDP or NaMMT). The rheological results showed that the AAC-modified bitumen samples displayed non-Newtonian characteristics associated with simple thermo-rheological materials. The AAC formulations A (DLTDP:furfural), D (Irganox acid:furfural) and F (DLTDP:Irganox acid:furfural) were shown to significantly strengthen the resistance of the bitumen samples to fatigue cracking. In contrast to Irganox acid:furfural combination, the addition of the NaMMT nanofiller to this mixture was found to enhance the rutting resistance of the aged bitumen samples.