Interfacial characterization of heavy naphthenic bitumen for paving

Abstract

In chapter 1 we describe the instruments and methods used in this thesis. The aim of chapter 2 is the evaluation of the interfacial energy of heavy naphthenic bitumen in water at different values of pH and at room temperature. We propose a new methodology based on the measurement of the bitumen surface tension at high temperature, the equilibrium contact angle of buffered water on heat-casted films of bitumen and the estimation of the bitumen-water interfacial energy at room temperature using the Young equation. Our strategy enables us to avoid the use of approaches for surface energy calculation, such as the polar-disperse components of surface tension and the equation of state. In chapter 3 we intend to understand the behavior of naphthenic bitumen in water due to the activation of endogenous surfactants. We measured the bitumen-water interfacial tension at high temperature for different pH values and the "underwater" wettability of bitumen films. We also examined the effect of calcium ions on the interfacial tension and electrical state of bitumen. Finally, in chapter 4, we examined the physicochemical interactions between bitumen and aggregate during bitumen spreading at high temperature. We monitored the spreading of sessile drops of liquid bitumen deposited on polished limestone aggregates. We selected limestone sheets due to their importance in road paving and because calcite is very chemically active. We studied two bitumens with different interfacial, rheological, and chemical properties: naphthenic bitumen and asphaltic bitumen.