<正>TiO_2 can be integrated in the cement manufacturing process to produce photocatalytic cement.Normal daylight can be used for the photocatalytic reaction(Beeldens,2006). When this type of cement is used in concrete structures,a charge is created on the surface that reacts with external substances to decompose air pollutants such as NOx (Chusid,2006).Ti02 can be integrated into a concrete surface to act as an accelerator for the natural oxidation process.It promotes faster decomposition of NOx and SOx from the air.(Essroc Italcementi Group,2008).Based on a review of the literature,a wide range(20-80%reductions) of pollution abatement efficiencies for NOx were observed when photocatalytic concrete or coatings were applied to infrastructure in the field.An explanation for the large range of measured NOx reductions relates to pollution monitoring techniques us well as the high variations in environmental conditions such as light intensity,relative humidity,temperature,wind speed and direction.This study entails an experimental study that compares the concrete properties of GU cement with concrete made w ith photocatalytic(PCAT) cement.The results reveal that PCAT cement concrete is more difficult to entrain air voids in and that it can achieve comparable mechanical properties to GU concrete.Further research is required to examine the transport and durability properties. Originality A significant amount of research has been conducted on evaluating the pollution-abating effectiveness of photocatalytic concrete.Most of the research has focused on NOx abatement.This study reviews laboratory and field studies that evaluate photocatalytic concrete as a building material.Although it is recognized that that there is a great deal of variability in field trials,this study identifies the daily and monthly variations in pollution concentrations as a critical variable.Furthermore,this study reveals that PCAT concrete can achieve similar mechanical properties in comparison to GU concrete,though more research is required to examine its transport and durability properties.
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