Indirect measurement of interfacial melting from macroscopic ice observations

Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.

Figure 1

Schematic diagram of our experimental equipment and definition of the ice-lens thickness $D$ and position $L$.

Figure 2

Photograph of a vertical cross section through a frozen sample with 0.6 $\mu$m particles. The horizontal dark zone is the ice lens and the white zones correspond to mixtures of glass beads, liquid water, and frozen pore ice.

Figure 3

Inferred film thickness as a function of the temperature depression below bulk melting (open circles) following a correction for the influence of particle curvature using $\lambda =d{(1+\alpha )}^{1/\nu }$, where $\nu =1.44$ corresponds with the best power-law fit. Open squares and triangles represent film thickness estimates against other substrates obtained by Sadtchenko and Ewing [5], and Gilpin [4]. The solid line shows the predicted film thickness against an ionized monovalent surface with a charge of $\sim$0.007 C m${}^{-2}$.

Figure 4

Comparison of ice-lens characteristics from numerical predictions (lines) and experimental observations (open circles), showing the position $\mathit{L}$ (a) and thickness $\mathit{D}$ (b) with different host particle sizes. Solid curves are for the best-fit power-law form with $\nu$ = 1.44; dashed curves for $\nu =3$ are also shown for comparison.