A new water-repellant concrete impregnated with tiny superstrong fibers promises to leave roads and bridges free of major cracks for up to 120 years.

University of Wisconsin-Milwaukee civil engineers have developed a concrete mix that is durable and superhydrophobic. They call it Superhydrophobic Engineered Cementitious Composite (SECC). Preventing normally porous concrete from absorbing water means that liquid can't get inside, freeze, and cause it to crack. The concrete's unusual characteristics, including being significantly more ductile than traditional concrete, means that cracks that do form do not propagate and cause failure.

"Our architecture allows the material to withstand four times the compression with 200 times the ductility of traditional concrete," said associate professor Konstantin sobolv, whose lab created SECC.

A report available on the Government Finance Officers Association lists the useful life of typical concrete roadways as 30 years and concrete bridges and culverts as 40-45 years. The UWM team says their improved material will hold up with little or no maintenance for well over a century.

To impart the characteristics in the material they wanted to see, they doped their mix with superhydrophobic additives based on siloxane, a compound that forms the backbone of silicones, mixed with superfine powders. Together, these form a microscopic spiky surface nearly impermeable to water. They also added unwoven polyvinyl alcohol fibers, each the width of a human hair, which are strong enough to let the concrete bend without breaking.

Last August, the team laid a 4-by-15-foot slab of their improved material as a patch to a university parking structure. They embedded sensors in their concrete to monitor moisture, stress and load. They are still analyzing whether the SECC they installed in the structure shows the performance improvement they saw in the lab.

They say the material, which would cost more than typical concrete, would pay for itself with diminished maintenance costs if it performs as they expect. It would also help with the sorry state of civil infrastructure across the country.