Curing and ageing of biofluxed bitumen: a physicochemical approach

Bitumen solutions, comprising of four bioflux-modified bitumens and one traditional slow-curing cut-back bitumen as a reference, were stabilised with two-phased process consisting of recovery and stabilisation parts. The oxidative long-term ageing (LTA) of the stabilised bitumen solutions was performed by a pressure ageing vessel (PAV). The generic fractions of the base bitumens were determined after LTA by thin-layer chromatographic method with flame-ionisation detector (IATROSCAN MK-6s). Complex shear moduli and phase angles of both base bitumens and bitumen solutions were examined with Physica 301 rheometer in oscillatory mode. The curing and ageing behaviour of the biofluxed bitumens differed notably from the traditional cut-back bitumen. Based on PAV and rheometer testing, the effects of ageing on the rheological properties of biofluxed binders may be solely bound to the evaporation of bioflux. Sigmoidal functions were introduced as an option for evaporation models with limited evaporation. However, interpretation of chemical composition of cut-back bitumens as analysed by thin layer chromatography-flame ionisation detector leaves a reasonable doubt for this method to give ultimate composition result.