Daily temperature swings can make water freeze and expand, then thaw and contract. Because concrete is porous and absorbs liquid, these changes often make its surface flake and peel. But researchers say a new process can help prevent such deterioration.
“The primary way in which we have resisted this freeze-thaw damage in the past was by using a technology that was developed in the 1930s, which was to put in tiny little air bubbles all throughout the concrete,” says Wil Srubar, a materials scientist and architectural engineer at the University of Colorado Boulder.
These flexible bubbles absorb some pressure but also reduce concrete’s strength, make it soak up more water and require a finicky distribution process.Srubar’s laboratory looked to the natural world, specifically “antifreeze” proteins that let some fish and bacteria endure frigid temperatures.
In cells, these molecules cling to ice crystals’ surfaces and prevent them from growing too large—but they do not function in highly alkaline cement paste, a key concrete ingredient. So the researchers tried a tougher substance with similar properties: a polymer called PEG-PVA, which is currently used in time-released pharmaceutical pills.READ MORE