New Concrete Can Clean the Air
posted by Paul Fiddian | 07.07.2010
A new type of concrete offers a new approach to reducing the impact of road vehicles on the environment in terms of emissions.
Aside from CO2, traditional (non-hybrid/electric) vehicles produce a variety of other gases, such as nitrogen oxides (NOX). Nitrogen dioxide (NO2) is an airborne pollutant which, when exposed to sunlight, is responsible for the creation of smog.
Persistent exposure to NO2 can cause health problems such as respiratory damage but recent trials of a concrete that strips the air of NO2 have indicated that the material could remove up to 45 per cent of the gas from the air.
These trials have been taking place in Holland for some months, after one road that received especially high volumes of traffic was recovered with the NO2-absorbing concrete in late 2009.
Researchers representing the Eindhoven-based University of Technology assessed the results produced by a 1,000 square metre patch of the material, compared to the same-sized area of standard concrete. In so doing, they established that the air immediately above this so-called air-purifying concrete had somewhere between 25 and 45 per cent less nitrogen oxide present.
According to a representative for the project, these physical trials followed earlier, lab-based analyses. “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”, Professor Jos Brouwers commented.
The air-cleaning concrete is manufactured by Dutch group Struyk Verwo Infra and can already be purchased for use on road surfaces and on walls, too.
While, in terms of cost, they are approximately twice as much as regular concrete stones, overall associated installation costs only come in at 10 per cent more than standard, according to Professor Brouwers.
The key to this concrete’s performance is the titanium dioxide it is filled with. Titanium dioxide has multiple applications – its ability to absorb ultraviolet light means that it forms a part of commercial sun creams, for example. Here, it scrubs the air of nitrogen oxide and nitrogen dioxide and, drawing on sunlight as a catalyst, transforms them into nitrate. This nitrate can then be washed away when rain hits the concrete.