Acta Scientiarum Polonorum

Abstract: The frost action in soils, in cold regions practically impossible to eliminate, and the complex structure of the soil medium determine a complicated nature of the problem. This problem still remains unclear for many reasons. First of all, the results presented in literature are partially incomparable. Such parameters of the experiments as the number of freeze-thaw cycles, the value of negative temperatures, the duration of freezing and thawing in each cycle and, of course, properties of soils used as the material, were different in all cases. Besides, the very important thing is to distinguish between the experiments carried in close and open systems. The latter, allowing the free water to be drawn upward from the water table to the freezing zone, better imitates the natural conditions. There are no evidences to what extent the cyclic freezing and thawing modify the microstructure and the pore-size distribution. This article presents the results of the significance of the impact of cyclic freezing-thawing and freezing the type of system to changes in the distribution of pores for the selected soils using multivariate analysis of variance. On the basis of quantitative analysis of SEM photographs, the analysis of pore-size distribution in selected representative samples of fives unfrozen cohesive soils subjected to one cycle of freezing in the open and closed systems. For comparative purposes, defined by two parameters characterizing the pore distribution curves obtained KDP: inequality of distribution index (β) and similarity index of pore-size distribution curves (ε).