Imaging of frost heave formations no longer frozen in time, thanks to 4D method

Freezing temperatures can raise the ground, potentially destroying roads and other infrastructure. The likely culprit? Frost heave, which happens when water in the soil freezes and elevates the ground through a complicated process that has, before now, not been visualized. Mirzaei et al. developed a method that allows scientists to study frost heave formation in situ in a first-of-its-kind study.

The team used combined X-ray and neutron computed tomography (CT) to visualize the evolution of ice lenses in a soil sample that froze over time while in contact with a liquid water reservoir. The scientists watched as the water infiltrated the soil, and a series of ice lenses formed and grew, thereby lifting the surface and the sample specimen — providing the first direct, time-resolved 3D visualization of this important freezing mechanism in porous media.

“Frost heave relies on the suction of liquid water from the underground, requiring both a downward temperature gradient and a fine-grained soil like clay or silt,” said author Fazel Mirzaei. “While the mechanisms underlying frost heave have been extensively studied, this study is the first to capture images of the individual ice lenses and their interaction with the porous medium and liquid flow in volumetric, time-resolved detail.”

The authors used X-ray CT to visualize the structural evolution of the soil itself, and neutron CT to distinguish between ordinary and heavy water to record the various ways water moved through and interacted with the soil as it froze.

The authors have identified several areas for further improvement, such as tracking faster phenomena and measuring internal stress and pore pressure.

Source: “4D imaging of frost heave and ice lens growth in silt using neutron and X-ray computed tomography,” by Fazel Mirzaei, Mukul Jaiswal, Daniyal Younas, Anders Kaestner, Katharina Scheidl, Basab Chattopadhyay, Ragnvald H. Mathiesen, and Dag W. Breiby, Applied Physics Letters (2025). The article can be accessed at https://doi.org/10.1063/5.0254006 .