Physicochemical characterisations of the bitumen–aggregate interface to get a better understanding of stripping phenomena

Our objective was to relate the fundamentals of bitumen–aggregate adhesion to practical engineering properties. The first step was dedicated to develop new physicochemical methods to characterise the bitumen–aggregate interface. Then, a relation was established between the physicochemical characterisations of the bitumen–aggregate interface and the water sensitivity of the asphalt. It was possible, by using the Drop Shape Analysis System, to apply the theory on the wetting of the textured surfaces distinguishing a one-scale roughness to a two-scale roughness on aggregate surfaces. Finally, a porosity effect corresponding to the smallest scale roughness leads to a better resistance to stripping phenomena. In addition, a chemical effect at the interface bitumen–aggregate, due to the addition of adhesion promoters in bitumen, improved the water sensitivity of the asphalt explained by an increase of the aromatics/resins ratio.