Concrete is hardly what you would think of as an environmentally friendly material, but it could be one way of combatting global warming – assuming you use the right type.
Researchers at Eindhoven University of Technology, in the Netherlands, have developed a special concrete that can reduce the amount of nitrogen oxide air pollution by as much as 45 per cent, according to a study published last month in the Journal of Hazardous Materials. The "photocatalytic" concrete is sprayed with titanium dioxide, a substance used in sunscreen because it blocks ultraviolet light. When mixed with concrete, it is able to break down nitrogen oxide, a pollutant emitted by cars and trucks.
In the study, researchers covered a stretch of road measuring 150 metres with the special concrete. Another part of the street, about 100 metres long, was paved with normal paving blocks. Over the course of a year, researchers tracked a range of factors, including traffic intensity, temperature, nitrogen dioxide and nitrogen oxide levels as well as wind speed and UV light irradiance.
The results were striking. The concentration of nitrogen oxide was on average 19-per-cent lower each day in the area with titanium dioxide concrete. The concentration was 45-per-cent lower under ideal weather conditions.
Does this mean that we can expect cities to be covered in this new concrete in the fight against pollution and global warming? Probably not. As Anna Hess writes on Takepart.com, "Titanium dioxide pavement is simply more expensive than your grandfather's cement."