Physique du séchage des sols et des matériaux de construction

Abstract : Drying of building materials and soils plays a major role in their final properties and is a main economics and environmental issue. In this thesis, we study the drying of complex porous media to better understand the impact of particles in the interstitial fluid. With a clear scale separation between the sample, pores and particles sizes, we observe water and particles distributions by camera, MRI, X-ray tomography and confocal microscope. We show that the fluid evolution and the drying kinetics are coupled. We study three kinds of fluids: pure liquid, hard and soft particles suspensions. The drying rate of pure water remains constant and generally persists until the majority of water is evaporated. The fluid flows through the porous network, due to capillary depression, to provide water to the free surface where evaporation occurs. We show, by Finite Elements Method, that the drying rate is very sensitive to the shape of the air/water interface. Particles suspensions always slow down the drying kinetics compare to pure water. At low volume fraction, particles migrate towards the surface and drying rate is linked to the increases of the compacted area. Soft particles can compress, thus the compacted area may shrink and influences drying rate. At high volume fraction, viscous dissipation is high and limit the fluid flow therefore particles do not migrate and the drying kinetics is slow
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Emmanuel Keita. Physique du séchage des sols et des matériaux de construction. Autre [cond-mat.other]. Université Paris-Est, 2014. Français. ⟨NNT : 2014PEST1172⟩. ⟨tel-01163712⟩

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