Calculation Method to Highlight Molecular Deagglomeration by Recycling Additives

Recycling additives are used in asphalt mixtures to restore aged bitumen properties, enhancing its performance and extending its service life. The addition of recycling additives can reverse rheological properties but the mechanism of their action is not well understood. The phase angle has been widely used to detect evolution in the chemical composition and the microstructure of bitumen. It is particularly sensitive to aging. The δ-method allows to estimate the apparent molecular weight distribution (AMWD) from rheological measurement. This approach has been used to propose an indicator named Molecular Agglomeration Index linked to the binder cracking susceptibility. In the present chapter, it is proposed to use it to assess the bitumen rejuvenation effect. Four blends are characterized rheologically before and after aging to see the effect of additives on the agglomeration of molecules. The research concludes that certain recycling additives not only dilute the asphaltenes in aged bitumen but have a real de-agglomerating effect.