Concrete roads could eat traffic pollutants

Highways England is reviewing measures to reduce elevated levels of traffic exhaust emissions. The answer could be at their feet believe Britpave, the infrastructure organisation.

The review follows increased concerns about the elevated levels of nitrogen dioxide (NO2) from increased traffic levels which on motorways have increased by almost a quarter over the last 20 years. Possible solutions include a network of 9m high pollution barriers installed at key locations across the strategic road network or the use of temporary 60 mph speed limits at peak times. However, there may be less visually intrusive answer than 9m high barriers.

“Highways England may well want to look at new concrete technology developments that offer the exciting possibility of concrete roads that absorb NO2 pollutants,” said Joe Quirke, Britpave chairman. “The addition of titanium dioxide to concrete means the concrete actually eats pollutants.”

Titanium dioxide (TiO2) is a photocatalytic material that reacts in sunlight to absorb nitrate oxides and convert them into harmless nitrates. It is increasingly available as a pavement spray or as an additive to concrete and adds 5 – 10% to the cost of a concrete road.

Quirke points to research carried out by the Eindhoven University of Technology in the Netherlands that found NO2 reduction of 35-40% in areas paved in concrete featuring TiO2. Researchers at the Public University of Navarre, Spain, are developing a nanoparticle coating for concrete uses photocatalytic reaction to reduce up to 90% of nitrogen oxides, 80% of hydrocarbons and 75% of carbon monoxides. In Segrete, Italy, a road treated by Essroc Italcementi with a TiO2 pavement spray resulted in a NO2 reduction of 60%.

“Pollutant eating concrete roads may sound like science fiction but they are a very real solution that should be considered”, said Quirke. “Plus they are the not the only environmental benefit of concrete roads. In addition, concrete roads can also be self-heating to reduce ice and snow-build-up, self-healing to reduce the need for repair and maintenance and energy conductive for easy wireless charging of electric vehicles as they travel over them. Plus, their thinner pavements, longer performance life and reduced maintenance means a reduced life cycle carbon footprint.”

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