Master of Science in Engineering Science (MSES)
Engineering Science (Interdepartmental Program)
Field trials of photocatalytic pavements were recently initiated and are presently being considered by many states (e.g., Virginia, Texas, New York, and Missouri). Results from this study originate from the country’s first air-purifying asphalt and concrete photocatalytic pavements, constructed on Dec. 20, 2010. The test area is a pavement site located on the LSU campus. The objective of the study is to validate field photocatalytic degradation of NOx in a field environment by measuring the day to day accumulation of the oxidized byproduct; nitrate salts. The mass of nitrates, produced by the real life photocatalytic pavement, were measured. The measurement was then correlated to the same mass of nitrates as recovered from laboratory samples with recorded NOx reductions in accordance to the Japanese Industrial Standards. This paper presents a nitrate sampling procedure, to be administered in the field, without the need for core sampling. Based on the results of the experimental program, the proposed method, quantify photocatalytic efficiency through nitrate measurements, was successful. There is evidence that photocatalytic degradation of nitrogen oxide was occurring in the treated section when compared to the control. The photocatalytic process was highly active during the first four days, followed by a decrease in the degradation rate of NOx. The decreased degradation activity might be caused by a continuous decrease in ambient NOx levels that occurred during the collection. Full regeneration of photocatalytic activity occurs in the field through a self-cleaning process during a rain event. Six months of traffic and in-service operating conditions proved to have negligible effects on the durability of the photocatalytic coating, when comparing the mass of nitrates recovered to just after installation. In addition, there was a good agreement between NO removal efficiency measured in the field after one day of nitrate accumulation with the laboratory experiment at the same level of relative humidity.
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Osborn, David James, "Quantification of NOx reduction via nitrate accumulation on a TiO2 photocatalytic concrete pavement" (2012). LSU Master's Theses. 4264.