The freezing of water is a notorious source of mechanical damage to materials, particularly noted during the cold winter months. A new study highlights how this damage can happen even when materials are only partially saturated with water, which is often surprising to many. Conducted by researchers Demmenie, Kolpakov, van Casteren, and their colleagues, the research reveals how the presence of liquid inclusions during the ice crystallization process is pivotal to causing damage to surrounding structures.
When temperatures plummet, many people have experienced the aftermath of freezing water – the catastrophic breakage of containers as ice expands. But what feeds this seemingly normal occurrence? Previous studies have primarily focused on frost damage, which typically occurs when water completely saturates its confines. This current work, published with the DOI: https://doi.org/10.1038/s41598-025-86117-5, unveils how higher pressures develop and fractures arise even under partially saturated conditions.
The research uses freezing experiments conducted at -30°C, employing cylindrical glass vials of different wettability properties to observe how ice interacts with water at various saturation levels. One of the main findings shows ice nucleation typically starts at the interface of the liquid meniscus when glass containers are used. This means as ice grows, the meniscus can freeze before the rest of the water, causing pressure to build up if any remaining liquid water becomes trapped.
This trapped liquid, when subjected to freezing, expands dramatically—up to nine percent—resulting in pressures powerful enough to fracture both the surrounding ice and the glass container itself. New calculations indicate these pressures can reach as high as 260 MPa, sufficient to cause breakage.
It appears the method of treating glass surfaces also plays a significant role. Hydrophobic treatments lessen the chances of creating these troublesome liquid pockets, shifting ice nucleation to the bottom of the glass, which allows more liquid to escape unconfined. "A hydrophobic treatment of the glass containers suppresses the curved shape of the meniscus to a flat one, shifting the ice nucleation point to the bottom of the glass," the authors note. This finding opens the door to new strategies for mitigating damage arising from ice growth.
The study goes even farther by showing the two-step process of ice crystallization, where fast-growing dendritic ice is followed by bulk ice crystal formation. This is integral to reducing fracture likelihood. Surprisingly, samples exhibiting dendritic crystallization before bulk formation experienced fewer fractures, likely due to air bubbles acting as compressibility reservoirs within the ice.
Earlier assumptions focused solely on volumetric expansion as the primary damage mechanism, yet these new insights broaden the perspective. The complex interactions involving wettability and nucleation points contribute to greater concrete understandings of how ice behaves during crystallization and its effects on surrounding materials.
The importance of these findings stretches beyond the laboratory and taps directly onto sectors reliant on maintaining structural integrity during freezing events. It's relevant for agricultural practices susceptible to frost damage, infrastructure management, and even art conservation where cold storage is often needed.
Overall, this study not only illuminates the underlying mechanisms of ice crystallization but also proposes practical solutions to prevent the costly damage associated with it. The researchers conclude, "Our findings support the idea: the water/air meniscus, with its contact angle against the glass wall, acts as geometric constraint similar to wedges, which promotes ice nucleation." Well-designed interventions, such as the use of hydrophobic containers, could provide much-needed relief from the harsh realities of frozen water damage.
Staying proactive about the design of materials across numerous disciplines may very well lessen potential injury caused by ice. With ice being such a commonplace and seemingly innocuous element, the depth of its influence requires careful consideration. Future work should seek to explore more geometric and material properties to deepen the analysis of ice's impact and contribute to more innovative solutions.