Grain Size and the Compressive Strength of Ice

This work presents the results of uniaxial compression tests on freshwater polycrystalline ice. Grain size of the test material ranged from 1.5 to 5 mm, strain rate ranged from 10⁻⁶ to 10⁻² s⁻¹ and the temperature was −5°C. The grain size effect emerged clearly as the strain rate increased to 10⁻⁵ s⁻¹ and persisted to the highest applied strain rates. On average, the stated increase in grain size brought about a decrease in peak stress of approximately 31 percent. The occurrence of the grain size effect coincided with the onset of visible cracking. The strength of the material increased to a maximum at a strain rate of 10⁻³ s⁻¹, and then dropped somewhat as the strain rate increased further to 10⁻² s⁻¹. Strain at peak stress generally tended to decrease with both increasing grain size and increasing strain rate. The results are discussed in terms of the deformational mechanisms which lead to the observed behavior.