Effect of vehicle classification and activity on field evaluation of photocatalytic concrete pavements’ ability to remove nitrogen oxides-a case study

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There has been an increasing interest in photocatalytic pavements, which can decompose pollutants to nonhazardous waste products with little energyrequirements and selectivity.The objective of this study is to evaluate the effects of vehicle activity and classification on nitrogen oxide (NOx) pollution emitted and correlating these factors to the NOx reduction from photocatalytic pavements. To achieve this objective, a field study was conducted with 22.3 m2of photocatalytic spray coated area and 22.3 m2 of uncoated control area. Evidence of photocatalytic reduction of NOx was evaluated by directly measuring NOx reductions from the ambient air.A traffic study was conducted for the photocatalytic control areas to characterize the variability in traffic classification and activity between the two areas and its effects on interpreting NOx reduction.Results showed that the amount of NOx emitted in the area predicted to be from traffic sources is no more than 5 grams per hour.Due to the low values of pollution emitted in the both the photocatalytic area and the control area, minor differences in traffic activity between these two areas resulted in significant differences in the amount of pollution emitted between the photocatalytic and the control areas.This may complicate the interpretation of the NOx reduction results. Furthermore,there was no significant linear correlation of vehicle class and speed and NOx reduction.

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International Journal of Pavement Research and Technology

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