A comprehensive evaluation of the photo-catalytic performance of recycled glass aggregate incorporated permeable cement-based mortar with TiO2 as a photo-catalyst

Abstract

This study aims to investigate the effectiveness of incorporating recycled glass aggregate (RGA) in TiO2-containing cement-based permeable mortars in terms of their photo-catalytic performance. To do this, standard and permeable mortars were produced with the RGA utilization rates of 15% and 30% (by weight of total aggregate content). Photo-catalytic activity of the mortars was evaluated through the determination of NOx and NO degradation capacities, NO2 transformation ratio and the selectivity, and their photo-catalytic activity performances were compared with each other and with reference specimens without any RGA to assess the efficiency of RGA utilization in terms of photo-catalytic degradation. Microstructural and mechanical properties of the mortars were also evaluated by performing scanning electron microscope (SEM) analysis and compressive strength test, respectively. According to the experimental results, regardless of curing age, utilization of RGA as aggregate caused decrements in the strength results because of the lower adherence capability with matrix. NOx degradation results indicated that permeable structure of the photo-catalytic mortars allows NOx species to diffuse to the inner part of the hardened specimen in favor of stimulation of photo-catalytic degradation reactions in deep along with the surface. RGA utilization was also allowed to penetration of UV lights throughout the matrix providing improved the photo-catalytic activity for the TiO2-containing specimens. The correlation between the selectivity results and the degradation rates of NOx demonstrates the reliability of selectivity as a parameter for evaluating the photo-catalytic performance.