Original data

The FP of clay and the gravelly soil was investigated under varying moisture contents and dry densities. Experimental results reveal distinct freezing curves for the two soil types. Clay exhibits supercooling at all moisture contents except 14%, with the longest stable freezing stage occurring at 20% moisture content. The gravelly soil typically exhibits supercooling, but no stable freezing stage is observed at 10% moisture content or dry density exceeds 1.6 g/cm3. Overall, the gravelly soil shows longer stable freezing durations than clay. Clay exhibits four distinct freezing curves, while the gravelly soil shows two. Each curve is characterized by the presence or absence of supercooling, stable freezing stages, and phase transition plateaus. The FP and supercooling temperature of both soil types decrease with increasing dry density and decreasing moisture content. The influence of dry density on these temperatures becomes more pronounced at lower moisture contents, whereas the effect of moisture content increases with increasing dry density. Meanwhile, the FP difference between dry densities decreases and becomes negligible as moisture content increases. Furthermore, moisture content has the greatest effect on the FP, followed by dry density, while soil type exerts the least influence. Clay exhibits a lower FP than the gravelly soil due to its higher fine particle content.