RAPID CITY, SD — Water expands when it freezes. This simple yet fundamental fact of nature can lead to cracks in building foundations, crumbling roads and huge rocks that fall onto canyon roadways from the cliffs above.
Past research into this problem has shown that when the ground freezes tiny pockets of ice trapped in the soil expands. This can create what is known as frost-heave in the winter and in the spring, when ground thaws it creates thaw-weakening settlement. Over time this freeze-thaw cycle causes damage to the ground and poses major challenges for human made structures, like bridges, dams, pipelines, buildings, roads and homes. Each year, the freeze-thaw cycle leads to billions of dollars in mitigation and repair costs around the world.
“We are trying to understand more about the fundamentals of ice formation underground and if there are natural methods that we can use to stop or control the ground from freezing,” says Tejo V. Bheemasetti, Ph.D., assistant professor in the civil and environmental engineering department at South Dakota Mines.
Bheemasetti is working alongside Bret Lingwall, Ph.D., associate professor in the civil and environmental engineering department at South Dakota Mines. The multidisciplinary project also includes a group of biologists at Mines, led by Rajesh Sani, Ph.D., a professor of chemical and biological engineering. The team is studying antifreeze proteins released from microorganisms that live in cold environments. These microorganisms naturally produce antifreeze proteins which keeps them alive in frigid conditions. Scientists want to know if this same kind of naturally occurring antifreeze could be used as an environmentally safe treatment in areas where the freeze-thaw cycle poses a threat to infrastructure.
“We are trying to develop a solution that is compatible with mother nature, so this requires both civil and biological engineers working together. It’s a wonderful interdisciplinary project,” says Bheemasetti.
Currently, engineers sometimes remove soils around structures that are susceptible to damage from the freeze thaw cycle. For example, they will pack gravel under the pavement that will behave better in freezing conditions. “If we could stabilize the soil with bacteria that contain natural antifreeze, we may be able to save money and time in construction,” says Bheemasetti.
Bheemasetti adds that a lot of research is needed before any of these ideas would be used commercially. “Before we ever test this in the field, we are testing it in the lab,” he says. “We will study how these natural antifreezes might work with various types of soils and how it might inhibit ice formation. This might have more applications than just protecting infrastructure.”
Bheemasetti uses environmentally controlled reaction chambers that mimic frigid outdoor conditions to test various forms of naturally occurring antifreeze in various soil types in various mixes and amounts. “We are trying to narrow many variables including optical mixing rates,” he says. “We are expecting the freezing point of treated soil will be much lower than normal.”
Sani and his team have spent years working on extremophilic bacteria, or microbes that thrive in hot water. Over the last year researchers expanded their work to include psychrophilic bacteria, or microbes that thrive in cold conditions. “Dr. Sani has provided the naturally occurring antifreeze and the psychrophilic bacteria he has grown in his lab. We will use his bacteria in our study of various soil types,” says Bheemasetti.
Developing a naturally occurring and environmentally safe antifreeze could have much wider applications than just soils. “Once we find one that works we can use the bacteria itself or come up with a bio-mimicking synthetic version that is much better for the environment,” says Bheemasetti.
The team has already begun its work on the three-year project. If successful, the next phase of the project could include longer-term field tests on a more real-world environment. “The solutions are there, the exact path uncertain, but it’s exciting to be taking these first steps,” says Bheemasetti.