Durability of NO Oxidation Effectiveness of Pavement Surfaces Treated with Photocatalytic Titanium Dioxide

Nowadays, photocatalysis has demonstrated to be a reliable solution in order to purify the atmosphere from the pollutants originated by vehicular traffic. Owing to the primary importance of this problem, the potential of innovative photocatalytic techniques, dealing with the immobilization of titanium dioxide TiO2 on the surface of the asphalt pavement, has been investigated. In particular, three different products, two bituminous emulsions and a cement mortar, were applied on the right lane and on the emergency lane of a highway section in Italy. The effectiveness of the photocatalytic treatments and its evolution with time were evaluated on cores taken after 1, 17, 46, 88, 218, and 527 days from the application of the products. Two tests were carried out on the cores: The NO degradation was evaluated through continuous flow tests, and the size of the treated areas was quantified by means of digital image analysis methods. The research showed interesting results, as all the techniques, in particular the bituminous emulsion-based products, proved to have a good effectiveness in air de-polluting, even if a decay of performance was noted, depending of traffic and weather conditions.