Evaluation of Nitrogen Oxide Reduction Performance in Permeable Concrete Surfaces Treated with a TiO₂ Photocatalyst

Fine dust, recently classified as a carcinogen, has raised concerns about the health effects of air pollution. Vehicle emissions, particularly nitrogen oxide (NO_x), contribute to ultrafine dust formation as a fine dust precursor. A photocatalyst, such as titanium dioxide (TiO₂), is a material that causes a catalytic reaction when exposed to light, has exceptional characteristics such as decomposition of pollutants, and can be used permanently. This study aimed to investigate NO_x reduction performance by developing ecofriendly permeable concrete with photocatalytic treatment to reduce fine dust generated from road mobile pollution sources. Permeable concrete specimens containing an activated loess and zeolite admixture were prepared and subjected to mechanical and durability tests. All specimens, including the control (CTRL) and admixture, met quality standard SPS-F-KSPIC-001-2006 for road pavement. Slip resistance and permeability coefficient also satisfied the standards, while freeze-thaw evaluation criteria were met only by CTRL and A1Z1 specimens. NO_x reduction performance of the permeable concrete treated with TiO₂ photocatalyst was assessed using ISO standard and tank chambers. NO_x reduction efficiency of up to 77.5% was confirmed in the permeable concrete specimen with TiO₂ content of 7.5%. Nitrate concentration measurements indirectly confirmed photolysis of nitrogen oxide. Incorporating TiO₂ in construction materials such as roads and sidewalks can improve the atmospheric environment for pedestrians near roads by reducing NO_x levels through photocatalysis.