Freeze–thaw cycles affecting rheological properties of Antarctic soils

Abstract

Antarctic soils are heavily affected by climate change in terms of properties and ecosystem functions. With increasing global temperatures, the frequency of freeze and thaw cycles of Antarctic soils will increase, thus affecting their mechanical behavior, with varying responses in erosion. This study quantitatively evaluated the effect of increasing frequency of freezing-thawing (F-T) cycles on rheological properties of four soils from the maritime Antarctica. Using an amplitude sweep test, the effects of 1, 5 and 9F-T cycles on soil micromechanics were evaluated and compared to a reference soil without F-T. These rheological parameters were determined: (i) the linear viscoelastic strain interval (LVR) (γLVR), (ii) the shear stress at the end of the LVR (τLVR), (iii) the maximum shear stress (τmax), (iv) the strain at the yield point (γYP), and (v) the storage and loss modulus at the yield point (G'YP). F-T cycles influenced soil rheological properties. Higher F-T frequency either increased or decreased γLVR and γYP, depending on the soil material. A 35% increase in τLVE occurred after one F-T cycle; however, at the fifth cycle a decrease of approximately 27% occurred, when compared to one cycle treatment, reaching similar values of no F-T. But after nine cycles, τLVE increased again by approximately 29% compared to previous treatment. The resistance and elasticity of the Antarctic soil microstructure showed great variation among the different soils, while soils with different textures behaved similarly for some rheological properties. Rheometry was confirmed as a method with little soil material consumption, however, soil rheology of Antarctic soils requires further studies to disentangle its interactions with soil chemical properties.