Evaluation of Environmental Effectiveness of Titanium Dioxide Photocatalyst Coating for Concrete Pavement

Abstract

Self-cleaning, air-purifying concrete pavement is a rapidly emerging technology that can be constructed with air-cleaning agents with a super-hydrophilic photocatalyst such as titanium dioxide (TiO 2 ). Although this technology has the potential to support an environmentally friendly road infrastructure, several design and operational parameters may affect its effectiveness and need to be evaluated. The objective of this study was to evaluate the environmental and mix design parameters that may affect the effectiveness of the environmental performance of TiO 2 coating. An experimental program was conducted: the effects of relative humidity level, flow rate of pollutants, and mix design parameters, including contents of TiO 2 and aggregate sizes, were investigated. The environmental efficiency of the samples to remove nitrogen oxides from the atmosphere was measured by using a newly developed laboratory setup. Results of the experimental program showed that the mix designs without fines achieved the highest photodegradation rates. In addition, the increase from 3% to 5% TiO 2 resulted in little improvement in the nitrogen oxide removal efficiency, which decreased with the increase in the humidity level and the pollutant flow rate.