The Effectiveness of Liquid PUD-TiO Photocatalyst on Asphalt Pavement.

Harmful nitrogen oxides (NO) are produced by vehicles, factories, mines, and power plants. In fact, over one million tons of NO are emitted into the atmosphere every year, making it the most prevalent air pollutant. Approximately 45% of the emitted NO in Korea is associated with the transportation sector. In this paper, the application of a new TiO photocatalyst on the asphalt roads to remove combustion-produced NO was studied. In an effort to overcome the known constructability, adhesion, cost, and dispersion problems associated with TiO photocatalysts, the liquid polyurethane (PUD) was added with TiO to form a mixture later known as liquid PUD-TiO. Laboratory and field tests were conducted to determine the optimum amount of photocatalyst to be used and the performance of asphalt pavement coated with PUD-TiO in terms of indirect tensile strength, water susceptibility, and rutting resistance. Additionally, the performance of PUD-TiO under different humidity, wind speed, and temperature conditions was also evaluated. The results showed that the application of PUD-TiO photocatalyst on the asphalt pavements road reduces the NO available on the surface of the road. The PUD-TiO also was found to have no effects on the performance of asphalt pavement. Meanwhile, under different weather conditions, the reaction between the photocatalyst and NO is mainly affected by the humidity.