9400637 Dash Technical abstract: The research studies the fundamental basis of premelting of ice and thermomolecular pressure, which cause frost heave in frozen ground. The dynamics of the efect are studied, by polarimetry and interference microscopy, on single crystal facets of ice, where interfacial melting causes a thin liquid film wetting the interface. The results are compared with theory, to investigate the orientation dependence and the proximity effect. A second part of the program studies transport of unfrozen liquid in monosized powders, as simple examples of porous media. Non-technical abstract: This program studies fundamental mechanisms of frost heave. Typically, in frozen ground, frost heave occurs as moisture is drawn toward lower temperatures. This project investigates the basic driving pressure and the flow of moisture, by measurements of the effect on a single crystal of ice. The experimental results are compared with prediction based on a new, detailed theory of frost heave. The program also includes a study of frost heave in porous media, using specially prepared artificial powders. These powders are more uniform than typical soils, thereby permitting a more detailed comparison with the theory. ***
