Functionalized building materials: Photocatalytic abatement of NOx by cement pastes blended with TiO2 nanoparticles

De-pollution activity of cement paste samples, added with 0.0%, 0.5%, 1.0%, 3.0% and 5.0% (based on the dry weight of the cement used) of titanium dioxide nanoparticles, TiO2, was evaluated through the degradation of nitrogen oxides, NOx, pollutants. Different blend of titania phases were considered as well, for each addition 100:0, 85:15 and 50:50 anatasa:rutile ratios were used. Measurements were carried out at two aging times, 65 h and 28 days, finding that at early ages the samples with the best photocatalytic activity, in terms of moles per square meter eliminated and percentage of conversion of NO and NOx, were the ones with a ratio of 85:15 and 5.0% of TiO2, while at late ages the samples with a ratio of 100:0 and 5.0% of TiO2.