This EAGER research project will test the hypothesis that titanium dioxide (TiO2) can function as a photocatalytic compound when used as a modifier to asphalt binder in the preparation of warm-mix asphalt (WMA). This would result in new class of asphalt mixtures with superior environmental performance while providing comparable mechanical performance to conventional mixtures. The proposed asphalt mixture will 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.
The results of this proposal may result in a new class of WMA that may be used to reduce air pollution in urban and metropolitan areas while achieving energy savings by lowering the amount of fuel required to heat asphalt mix during production and placement, reduction of emissions, and possibility of increasing Reclaimed Asphalt Pavements (RAP) contents in the mix without the need to raise mixing temperature. The planned activities are expected to enhance the understanding of sustainable construction materials for undergraduate and graduate students especially among underrepresented groups.
This research project tested the hypothesis that titanium dioxide (TiO2) can function as a photocatalytic compound when used as a modifier to asphalt binder in the preparation of Warm-Mix Asphalt (WMA). As a result, a new class of asphalt mixture with superior environmental performance was developed. This asphalt mixture combined 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. This is the first time that such a novel approach was attempted in order to combine the benefits of WMA and TiO2 into a single superior product. Educational activities allowed recruiting and engaging three students from underrepresented groups into the proposed laboratory activities. Two graduate students that are pursuing their PhD at LSU and two undergraduate students participated in this project. In addition, findings of this research will be used in two undergraduate courses currently taught by the PI at LSU. Based on the results of this project, the following outcomes are reported: When used as a modifier to asphalt binder in the preparation of WMA, the photocatalytic compound was not effective in degrading NOx in the air stream. This could be attributed to the fact that only a small amount of TiO2 is present at the surface. When used as part of a surface spray coating, TiO2 was effective in removing NOx pollutants from the air stream with an efficiency ranging from 38 to 77%. Rheological test results indicated that the addition of TiO2 did not affect the physical properties of the conventional binder. In addition, exposing the binder to UV light did not appear to accelerate the aging mechanisms in the binder. The use of TiO2 as a binder modifier improved the mix fracture resistance at 3, and 5% while it did not have a noticeable effect when used at a content of 7.0%. The increase in flow rate and relative humidity negatively affected the effectiveness of the NOx reduction efficiency. However, the increase in UV light intensity improved the NOx removal efficiency of the surface coating. As a result of this study, the research team has started field testing of the technology. The research team published two journal papers and one conference paper as a result of this project. The undergraduate students that participated in the research were able to gain an understanding of the importance of air quality and sustainability in construction. They learned about nano materials and how they can be integrated to improve environmental performance. One of the undergraduate students started pursuing a Master degree at LSU.
