A comprehensive method of determining the soil unfrozen water curves: 1. Application of the term of convolution

Because none of the existing methods of measurements of the unfrozen water content are able to indicate the real phase changes in individual soil sample in detail, a method based on the differential scanning calorimetry (DSC) is presented. The method consists in determining the real heat flux function q(T) absorbed by the frozen soil sample during the warming DSC run. It is based on searching for a distribution of “heat impulses” in relation to temperature, which convoluted with the apparatus function a(T) that gives a minimal deviation from the observed heat flux function h(T). The function q(T) can be easily related to the function of unfrozen water content u(T). The latter determines such important parameters of the soil freezing process as the melting point T0 and the content of “nonfreezable” water un.