A Breakthrough Concept in the Preparation of Highly-Sustainable Photocatalytic Warm Asphalt Mixtures

The objective of this study is to test the hypothesis that titanium dioxide (TiO2) can function as a photocatalytic compound when used in the preparation of warm-mix asphalt (WMA). The proposed asphalt mixture would combine the benefits of WMA such as reduced energy consumption and emission during production with the photocatalytic properties of TiO2 to trap and degrade organic and inorganic particles in the air. Two application methods were evaluated, using TiO2 as a modifier to asphalt binder in the preparation of WMA and applying TiO2 to the pavement surface as a water-based solution. Results of the experimental program indicated that the use of TiO2 as a modifier to asphalt binder was not effective in removing NOx pollutants from the air stream; however, the application of TiO2 as part of a water-based spray coating achieved a NOx reduction efficiency ranging from 39 to 52%.