Relations between Linear ViscoElastic Behaviour of Bituminous Mixtures Containing Reclaimed Asphalt Pavement and Colloidal Structure of Corresponding Binder Blends

The paper presents an attempt to find a relation between Linear ViscoElastic (LVE) behaviour of bituminous mixtures containing Reclaimed Asphalt Pavement (RAP) and colloidal structure of corresponding binders. Three different base bitumens (15/25, 35/50 and 70/100 pen grade) were used to produce nine bituminous mixtures with varying RAP content (0%, 20%, 40% and 60%). Moreover, a 100% RAP mixture was produced (containing only RAP-extracted binder), for a total of ten mixtures. All mixtures have the same aggregates and grading curve. For each mixture, its corresponding binder blend was also produced, by perfectly mixing the base binder with RAP-extracted binder in the same proportions. Tension/Compression (T/C) complex modulus tests were performed on all mixtures, over a large range of frequencies (from 0.001Hz to 10Hz) and temperatures (from -25°C to 40°C). Experimental results were successfully fitted with the 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) analogical model, developed at ENTPE. Therefore, for each mixture, a set of 7 model parameters and 2 additional constants (to take into account Time-Temperature Superposition Principle) was obtained. All binders were subjected to penetration tests and SARA (Saturates, Aromatics, Resins and Asphaltenes) fractioning, in order to have an indication on their colloidal structure. Colloidal Index (CI) of each binder was also calculated. Correlations between each parameter and all SARA fraction proportions, corresponding colloidal index values and penetrations are presented and analyzed.