Earlier this month, Jos Brouwers, a professor of building materials at Eindhoven University of Technology (Netherlands), reported that tests on a new stretch of roadway in the municipality of Hengelo indicate that concrete coated with titanium dioxide can significantly cut residual NOx automobile emissions, a major source acid rain and smog.
In a lecture at the school, Brouwers said that as part of a road resurfacing project, around 1,000 square meters of the road’s surface were covered with special concrete paving stones containing the titania. For comparison purposes, another area of 1.000 square meters was surfaced with normal concrete pavers.
Researchers took measurements at heights of between a half and one-and-a-half meters. The results were significant:
“Over the area paved with air-purifying concrete the NOx content was found to 25 to 45 per cent lower than that over the area paved with normal concrete. ‘The air-purifying properties of the new paving stones had already been shown in the laboratory, but these results now show that they also work outdoors,’ said professor Brouwers. Further measurements are planned later this year.”
The titania in the pavers photocatalytically converts removes the nitrogen oxides from the air and converts it into nitrate. The idea of using titania technology on concrete for roads and construction aren’t particularly new, but this is the first time I have seen measurements taken from an actual roadway.
The concrete stones were made by paving stone manufacturer Struyk Verwo Infra. Although they are available for sale, they cost about 50% more than their non-treated counterparts. However, Brouwers argues that these materials are only a relatively small part of the cost of road construction and that the use of these pavers effectively adds only 10% to the cost of a project. Thus, they may be cost-effective response in regions where maximum NOx emissions are being exceeded.
Brouwers also says the concrete can be combined with asphalt when an asphalt surface is preferred.