Ageing Effects on a Softened Bitumen by the Addition of DSA (Dodecenyl Succinic Anhydride)

The softening of aged bitumen is necessary for a successful asphalt rejuvenation in road recycling operations. Thus, this study proposes a novel and successful approach by using Dodecenyl Succinic Anhydride (DSA), a reactive surfactant with a polar head capable of reacting with some polar compounds of bitumen. On this basis, this paper analyses the softening potential and ageing inhibition capability of the addition of 3 wt.% DSA before and after the application of standard laboratory ageing methods (rolling thin film oven, RTFOT and pressure aging vessel (PAV) tests). To that end, different modified bitumens were evaluated by analysing the linear viscoelastic behaviour, viscous flow properties, thin layer chromatography, Fourier transform infrared spectroscopy (FTIR), contact angle measurements and compactibility tests. The results obtained for DSA show its greater potential to soften a model bitumen, when compared to a diluent oil, through physico-chemical processes that bring about a lowering in the polarity along with the alteration of its colloidal stability. Even though ageing processes in bitumen negatively affect its softening capacity, the developed structures still retain the ability to partially compensate for the adverse hardening effects. Furthermore, DSA addition greatly enhances the binder's wettability on a siliceous-type aggregate and favours asphalt compaction.