Concrete pavements containing TiO 2 can be used for air pollution control by oxidizing NO X under UVbearing sunlight. This study employed a bench-scale photoreactor to estimate NO oxidation rates for varied environmental conditions. Rates correlated positively with NO inlet concentration and irradiance and negatively with relative humidity. No correlation occurred with flow rate. A decrease in slab moisture (previously unstudied) positively correlated with NO oxidation rate at 0-2% loss of saturated mass, but negatively correlated at losses greater that 2%. Although prior researchers deemed temperature insignificant, data indicated a positive correlation. Overall, rates ranged from 9.8-64 nmol•m-2 •s-1 .

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Pavements which have been blended, coated, sprayed, etc., with photocatalytic TiO 2 additives have attracted world-wide interest during the past decade-plus period based on their environmentally beneficial abilities to provide reactive (i.e., 'smog-eating pavement' plus 'self-cleaning') and reflective (i.e., 'cool pavement') impacts. The former 'reactive' capabilities notably involve a de-polluting property where TiO 2 irradiation with UV-A spectrum light is able to oxidatively convert a variety of problematic organic and inorganic pollutants within both atmospheric and aqueous runoff zones. This suite of transportation-generated amenable contaminants notably includes NO X residuals which otherwise represent a serious environmental and human-health challenge within high traffic density, inner-urban highway locations with high-density adjacent resident populations. Multiple laboratory-level photo-reactor studies published over the past several decades have demonstrated this photocatalytic NO X -removal capability, while at the same time scientifically exploring and elucidating key relationships between NO X abatement and various environmental factors (e.g., light wavelength and intensity, ambient relative humidity and surface moisture, pavement temperature, surface soiling impacts, etc.). Field monitoring, albeit in more limited fashion, has provided similarly supportive findings at a number of locations involving not only TiO 2 -bearing pavements but also locations paved with blocks, pavers, bricks, etc. which have been sprayed or coated with TiO 2 -enriched admixtures. This chapter, therefore, provides an overview of the related literature covering academic, industrial, patent, and related perspectives and both experimental and full-scale findings. While this existing body of knowledge is substantial, complementary

His dissertation research is focused on photocatalytic degradation of nitrogen oxides by concrete pavement containing titanium dioxide. In Jan. 2013, he will assume a faculty position in the Engineering Department at