Pervious concrete with titanium dioxide as a photocatalyst compound for a greener urban road environment

The United States is facing the problem of controlling air pollution from vehicle emissions, especially in growing urban areas. This study investigates the photocatalytic effect of titanium dioxide (TiO ₂) applied onto pervious concrete pavement to remove some of these pollutants from the air, so that pervious concrete pavement can be installed for two sustainable applications: storm water management and air pollutant removal. The photocatalyst, TiO ₂, activates with UV radiation to oxidize air pollutants, such as nitrogen oxides (NO _x) and volatile organic compounds (VOCs). This study compared different methods to apply TiO ₂ onto the surface of pervious concrete and measured the photocatalytic activity of the concrete, the infiltrating characteristics of the pervious concrete, and its ability to withstand environmental impact. High pollutant reductions were seen with a driveway protector mix, a commercial water-based TiO ₂ preparation, TiO ₂ in water, a cement-water slurry with low cement concentration, and the commercial PURETI coating. It was found that nitrogen oxide (NO) was efficiently removed with each of these treatments, while VOCs displayed more variability in removal efficiency. Different coating methods can cause different degree of infiltration rate reduction depending on the specific design of coating materials while none of the application methods decreased the infiltration rates below levels applicable for standard hydrological design. When pervious concrete was compared to traditional concrete, pervious concrete showed higher NO reductions.