MoDOT to Test Smog-eating Concrete

ST. LOUIS, MO (October 6, 2011) – The Missouri Department of Transportation and its contractor, Fred Weber Inc., will test a new type of concrete on a section of Route 141 in St. Louis in October.

Crews will place concrete with a photo-catalytic additive of titanium dioxide (TIO2) on a stretch of new concrete for the project on October 19, weather permitting. This additive absorbs smog, uses sunlight to break it down, and releases it as nitrogen and carbon dioxide. MoDOT believes this additive, which has been used in Europe, is being tested for the first time in the United States.

Workers will use a process called two-lift paving to place this section of concrete. In this process, crews will lay down a thick layer of concrete and then immediately place a second, thinner "lift," or layer of concrete on top of that thick layer. Concrete placed using this method is as strong as that used on standard concrete pours.

This process lets the department place two different concrete mixtures. Since the titanium dioxide additive is expensive, this paving technique lets the department use the additive in the thinner top lift while still getting the benefit of a thick slab of concrete.

MoDOT will test a 1,500 foot section of the new Route 141 with this smog-eating concrete.