AIR-PURIFYING STONES ON TRIAL
The Dutch University of Twente (UT) are paving a test road section in the Dutch city of Hengelo with air-purifying stones. These concrete stones contain titanium dioxide, a photocatalytic material, which uses sunlight to convert the nitrogen oxides in the air into harmless nitrates. The rain then washes the streets clean.
Based on a Japanese invention, the stones were further developed and their effectiveness demonstrated by the UT in its concrete research laboratory. The next step is to test the stones in practice. The test street will be divided into two sections: one half will be paved with conventional stones and the other half with air-purifying ones. The air quality will then be measured in each section to test the effectiveness of the stones. As an added bonus, the stones repel dirt and therefore always stay clean.
The location in Hengelo was chosen because of the volume of traffic and the fact that the road is being reconstructed. The local air quality is currently well within the norm.
This trial is being carried out with stone producer Struyk Verwo Infra. The road reconstruction is expected to be completed by the end of the year. Measurements will then start early next year, with the first test results expected around the middle of 2009.