Volume 40, Issue 6 (November 2012)
Mechanical Characteristics of Asphaltic Mixtures Containing Titanium-Dioxide Photocatalyst
Photocatalysis pavements containing nano and ultrafine titanium dioxide (TiO2) can trap and degrade organic and inorganic particles in the air, removing harmful air pollutants, such as nitrogen oxides (NOx) and volatile organic compounds in the presence of UV light (sunlight). To accommodate the rapid development and adoption of this technology, performance characterization of photocatalytic mixture is needed. The objective of this study is to conduct a comprehensive laboratory evaluation of conventional HMA and WMA mixtures containing the nano TiO2 photocatalyst. To achieve this objective, two asphalt cement binder blends, consisting of an unmodified PG 64–22 and SBS polymer-modified PG 70–22, and a commercial crystallized anatase-based titanium-dioxide ultra-fine powder with an active surface area of 90 m2/g were prepared at a modification rate of 7 % by weight of the binder. The blends were used in 19-mm Superpave asphalt mixtures. The content of Evotherm J1 WMA additive was 1.0 % by weight of the binder. The mixture performance tests included modified Lottman test, SCB, LWT, and TSRST. Based on the results of the experimental program, the use of TiO2 as a modifier to HMA and WMA mixtures did not significantly alter the performance as compared to conventional mixes; therefore, TiO2 may be used to modify both HMA and WMA mixtures without damaging effects on performance.