Establishing a relationship between particle size distribution & thaw weakening susceptibility in soils

Susceptibility to frost action in soils is an important consideration in cold and seasonably cold regions. Whilst the particle size distribution (PSD) is commonly used to measure susceptibility to frost action, this method is typically seen as unreliable. Moreover, susceptibility criteria are generally specific to frost heave despite heave and thaw weakening both being described by the term frost action. Therefore, the effect of PSD on thaw weakening has not been fully explored. This study sets out to establish a relationship between PSD and thaw weakening susceptibility considering a better set of PSD descriptors than those traditionally used (e.g. d₅₀, C_u and C_c) towards the entire PSD. By examining available experimental data in the literature, in particular studies used to establish existing thaw weakening susceptibility criteria and testing set out in ASTM D5918–13, it was found that PSD influences thaw weakening susceptibility. PSDs located to the right of the stability line in the normalised entropy diagram (used to characterise PSDs) were found to be largely non-susceptible, whereas finer PSDs to the left the stability line were found to be highly susceptible to thaw weakening. It was also found that PSD greatly affects changes in bearing capacity after thawing. The analyses presented here demonstrate that the grading entropy stability criteria has significant potential as a method of predicting thaw weakening susceptibility.