Self-cleansing of rigid pavements by using flyash and titanium dioxide.

Abstract This study innovatively investigates the use of TiO₂ particles and flyash with cement to reduce pollution. The study was conducted by replacing OPC with photocatalytic concrete, prepared by partial replacement of cement with TiO₂ and flyash. As it is a chemically stable and versatile semiconductor, TiO₂, when incorporated into concrete mixes as a photocatalyst, degrades organic pollutants like NOx, SOx etc. in the presence of UV light radiation. For the best efficiency of TiO₂, flyash was added, which not only adds to the durability of concrete but also increases the porosity of concrete, and thus increases the number of active sites for the photocatalytic reactions to take place. The M30 concrete mix ratio was used for the casting of nominal and photocatalytic concrete. Cement was partially replaced by 10%, 15% and 20% flyash. TiO₂ was used as 1.6%, 2.2%, and 2.6% by the weight of M30-grade concrete. Concrete cubes were made based on combinations of varying percentages of flyash and TiO₂ for the slump cone test and compressive strength test. The early compressive strength, though decreased due to addition of flyash but attained the peak value of 42.65 N/mm² at 15% flyash which further increased to 52.60 N/mm² for the combination of 15% flyash and 2.6% TiO₂. The photocatalytic activity of TiO₂ and degradation of pollutants was investigated by exposing the cubes sprayed with methylene blue dye as a model pollutant and structurally by the Fourier transform infrared spectroscopy test, where the graphs obtained were compared with the reference graphs.