Experimental study on the rate dependent strength of ice-silica mixture with silica volume fractions up to 0.63

Abstract

We conducted deformation experiments of ice-1 μm silica beads mixture to clarify the effects of silica beads volume fraction and temperature o1i the strength. The silica beads volume fraction was changed from 0 to 0.63 to simulate the surfaces of icy bodies. Unconfined uniaxial compression tests were made in a cold room at the temperatures from -10°C to -25°C and the constant strain rates ranged from 2.9 × 10 -3 to 8.5 × 10 -7 s -1. We determined the rate dependent strength of the mixture written by ∈̇ = A · σ n max from the relationship between the maximum stress, σ max on the stress-strain curve and the applied strain rate, ∈̇. At -10°C, the mixtures with silica volume fractions of 0.004-0.04 had almost the same strength with pure ice and the stress exponent, n, is about 3. On the other hands, at the silica volume fractions more than 0.15, the mixture became harder as the beads were more included, and it had the same stress exponent, about 6. This high stress exponent might be caused by crack generation. Also, we found that the A for silica volume fractions more than 0.15 was written by an exponential equation related to the silica volume fraction, øo, A = 6.86 × 10 -8 exp(-6.35øo). Furthermore, we found that the n of øo = 0.15 was independent of the temperature, and the brittle-ductile boundary of øo = 0.29 and 0.63 was more than 30°C higher than that of pure ice. Copyright 2008 by the American Geophysical Union.