Magnetic Resonance Imaging of drying bitumen emulsions

Abstract From Magnetic Resonance Imaging (MRI) measurements allowing to distinguish separately the density distribution of the two phases of the system, we show that bitumen emulsions essentially dry homogeneously, with nevertheless a slight concentration gradient increasing towards the sample free surface exposed to air. Remarkably, despite the resulting large concentration of bitumen droplets formed around the free surface of the sample, the bitumen droplets do not coalesce before the very last stages of drying. In parallel the drying rate strongly and continuously decreases, which is attributed to the reduction of the hydraulic network connected to the sample free surface.