Secrets to cementing the sustainability of our future infrastructure may come from nature, such as proteins that keep plants and animals from freezing in extremely cold conditions.
CU Boulder researchers have discovered that a synthetic molecule based on natural antifreeze proteins minimizes freeze-thaw damage and increases the strength and durability of concrete, improving the longevity of new infrastructure and decreasing carbon emissions over its lifetime.They found that adding a biomimetic molecule—one that mimics antifreeze compounds found in Arctic and Antarctic organisms—to concrete effectively prevents ice crystal growth and subsequent damage.
This new method, published today in Cell Reports Physical Science, challenges more than 70 years of conventional approaches in mitigating frost damage in concrete infrastructure.“No one thinks about concrete as a high-tech material,” said Wil Srubar III, author of the new study and assistant professor of civil, environmental and architectural engineering.
“But it’s a lot more high-tech than one might think. In the face of climate change, it is critical to pay attention to not only how we manufacture concrete and other construction materials that emit a lot of carbon dioxide in their production, but also how we ensure the long-term resilience of those materials.”Concrete is formed by mixing water, cement powder and various aggregates, like sand or gravel.
Since the 1930s, small air bubbles have been put into concrete to protect it from water and ice crystal damage. This allows any water that seeps into the concrete to have room to expand when it freezes. Without it, the surface of damaged concrete will flake off.But this finicky process can come at a cost, decreasing strength and increasing permeability. This allows road salts and other chemicals to leach into the concrete, which can then degrade steel embedded within.
“While you’re solving one problem, you’re actually exacerbating another problem,” said Srubar.As the U.S. faces a significant amount of aging infrastructure across the country, billions of dollars are spent each year to mitigate and prevent damage. This new biomimetic molecule, however, could dramatically reduce costs.In tests, concrete made with this molecule—instead of air bubbles—was shown to have equivalent performance, higher strength, lower permeability and a longer lifespan.