Research On Photocatalytic Activity Of Titanium Dioxide Modified Recycled Fine Aggregate Mortar

China’s construction industry has been under the rough development mode for a long time.In the past 50 years,about 30 billion cubic meters of clay bricks have been produced.Most of these clay bricks will be converted into construction waste in the next 50 years.China’s recycling rate of glass is far lower than the world average,at 11.8%.At the same time,the environmental problems brought by the acceleration of industrialization,such as air quality,are increasingly serious,especially the haze weather caused by nitrogen oxides and sulfur dioxide,photochemical smog,greenhouse effect,acid rain and other pollution seriously affect human production and lifestyle.The combination of photo-catalysts and building materials is an important development in the photocatalytic degradation of air pollutants and the alleviation of air pollution.In this paper,the composite photo-catalyst of recycled clay brick sands and recycled glass cullets were prepared by using reclaimed recycled clay brick sands and recycled glass cullets as the support of supporting nano-TiO₂,and the basic properties of composite photo-catalytic mortar with nano-TiO₂ as the catalyst and the degradation effect of pollutants were systematically studied.At the same time considering the process of sands in the preparation of recycled clay brick sands will produce large amounts of r recycled clay brick powder,powder with strong pozzolanic activities and regeneration of recycled clay brick sands,studied the regeneration of recycled clay brick powder as auxiliary cementitious materials to replace cement inhibition caused by glass and the best dosage of the possibility of alkali aggregate reaction,the experimental results showed that the optimum content of recycled clay brick powder is 25%.The supporting capacity of three kinds of aggregate（recycled clay brick sands,recycled glass cullets and standard sand）to nano-TiO₂ was studied,and it was found that the supporting capacity of regenerated recycled clay brick sands was the strongest,followed by recycled glass cullets,and the standard sand was the weakest.Moreover,the photo-catalytic degradation effect of composite photocatalytic mortar panel on NO_x was used to determine the optimal doping amount and method of nano-TiO₂,and the optimal replacement amount of glass cullets composite photocatalyst was also determined.Experimental results show that with ultrasonic crusher to the concentration of 1%for ultrasonic dispersion of nano-TiO₂solution and the carrier are soaking adhesion preparation of composite photocatalyst,clay brick sands composite photocatalyst and glass cullets composite photo-catalyst mix of 60%and 40%respectively,the composite photo-catalytic mortar best photocatalytic degradation effect of NO_x.In addition,the effects of the velocity and concentration of NO_x/SO₂ and curing time on the photocatalytic effect of composite photocatalytic mortar were also studied.The results showed that,with the increase of the velocity or concentration of nitrogen oxides or sulfur dioxide,the photocatalytic degradation rate of photo-catalytic mortar to both gases showed a downward trend,and the photocatalytic degradation rate of photocatalytic mortar to NO_x also showed a downward trend with the prolapse of curing time.After curing for 90 days,the photocatalytic degradation rate decreased by 22%Using recycled clay brick sands and recycled glass cullets as supporting nano-TiO₂ to prepare composite photo-catalytic mortar not only has great application potential in photo-catalytic building materials,but also is a feasible method of recycling solid waste,which greatly improves the high value-added utilization of clay brick and glass.