2014-05-05

Co.Exist

Water-Repellent Concrete Could End The Scourge Of Potholes

A new kind of super road surface promises to keep bridges safe during the springtime thaw.

Water: the foundation of all life—and all potholes.

That's why researchers from the University of Wisconsin-Milwaukee have invented a kind of pothole-proof super concrete. According to them, the new pothole-solving concrete is extremely water-resistant and can last up to 120 years.

Potholes happen when water seeps into concrete’s air pockets, freezes, and expands. Breaks in the road can also occur when the ice melts and pushes water up to the surface. However, Superhydrophobic Engineered Cementitious Composite (blargh), or SECC, is crazy water-proof, as you can see from the video above. Fibers coated with a hydrophobic, water-based emulsion stick up out of the surface (like bristles on a brush) to repel water molecules.

The secret of SECC lies in those fibers. UWM professor Konstantin Sobolev has been working on water-repellent concrete for nearly two decades, but recently discovered that microscopic polyvinyl alcohol fibers allowed the material to flex, where conventional concrete would simply split and break. His lab was also able to control the composition and size of the material’s airways, which, in normal concrete, arrive large and irregular. By making the airways smaller but more evenly spaced and traversing them with fibers, Sobolev was able to create a material that would bend rather than crack while under stress.

The SECC being tested for flexibility.

“Most accidents happen in fall or end of spring, when there’s freezing in the roads,” Sobolev explains. “Here in Wisconsin, just a few days ago it was a rainy day and suddenly it was cold and we had ice on the roads. Many accidents happened that way. [SECC] could save lives.”

So far, Sobolev’s lab has tested the material on the university’s own parking ramp. They’ve also inserted carbon nanotubes and 100 electrodes into the material to communicate to scientists how much moisture the ramp will be able to absorb, and how much stress it will be able to take. The researchers’ ultimate goal is that SECC is used commercially to prop up (and communicate with) bridges.

But while SECC holds a lot of promise for pothole applications, too much of it could be dangerous. Impervious, concrete surfaces are contributing to a crisis of stormwater runoff from cities, the kind that can flood sewage systems in a bad rain and push all kinds of pollution out to waterways. Sobolev acknowledges this, but notes that on some surfaces, like bridges, runoff will happen no matter what. Plus, not all applications of the stuff have to be “superhydrophobic.” If you leave off the water-repellent coating, this type of concrete remains remarkably durable, he says.

[Image: Potholes via Shutterstock]

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