Microstructure of freezing front in freezing soils

A series of freezing tests on Kanto loam were conducted under various test conditions of a temperature and an applied load to find the microstructure of the freezing front in a freezing soil by the use of CCD camera with the resolving power of a few microns. Analyzing the microscopic pictures taken in the part between the growing surface and the frost front (0°C), so-called the frozen fringe, we found no significant change of microstructure. On the other hand, in the thin frozen part close to the growing surface of ice layer, we found that significant changes of microstructure occur. This thin frozen part may be regarded as the part of transitional zone in the freezing soil.