Assessment of the long-term photocatalytic performance of cementitious systems incorporating different mineral admixtures

ŞAHİN O.

Construction and Building Materials, cilt.354, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 354
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1016/j.conbuildmat.2022.129215
  • Dergi Adı: Construction and Building Materials
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, CAB Abstracts, Communication Abstracts, INSPEC, Metadex, Veterinary Science Database, Civil Engineering Abstracts
  • Anahtar Kelimeler: Titanium dioxide(TiO2), Photocatalytic efficiency, Cement-based systems, Nitrogen oxides(NOx) degradation, Carbonation Hydration, PORE-SIZE DISTRIBUTION, C-S-H, ACCELERATED CARBONATION, PORTLAND-CEMENT, FLY-ASH, NOX REMOVAL, MICROSTRUCTURE, MORTARS, CONCRETE, METAKAOLIN
  • Ankara Üniversitesi Adresli: Evet

Özet

© 2022 Elsevier LtdThis work aims to perform an experimental study to examine the long-term photocatalytic performance of TiO2-incorporated cementitious systems under carbonation exposure and the effect of the incorporation of different mineral admixtures (metakaolin or calcite) on the time-dependent photocatalytic performance stability of the cementitious systems. To do this, TiO2-containing mixtures were produced by replacing cement with different mineral admixtures (metakaolin or calcite) at a mass percentage of 15 and 30 % of total powder material. Produced specimens were kept under two different environmental conditions [95 ± 5 % relative humidity (RH) and 20 ± 2 °C (Curing Condition I), and 65 ± 5 % RH, 50 ± 5 °C and %4 CO2 (Curing Condition II)]. Photocatalytic activity of the specimens was assessed by determining NOx degradation rate (%), NO degradation rate (%), NO2 formation rate (%) and system selectivity (%) via photocatalytic degradation tests. To assess the microstructural, physical and chemical properties of the specimens, mercury intrusion porosimeter (MIP) and thermogravimetry (TG/DTG) analyses were used. The results indicated that metakaolin incorporation into the cement-based systems enhanced the long-term photocatalytic performance of the specimens. For Curing Condition II, a better time-dependent performance stability was achieved from the mixture with higher metakaolin incorporation rate. Calcite incorporation into the cement-based systems also improved the time-dependent photocatalytic performance of the mixtures, which was more pronounced for the high calcite incorporation rate. While the carbonation mechanism determined the time-dependent photocatalytic performance of the metakaolin-incorporated mixtures, the presence of defects in the matrix because of the calcite incorporation determined that of the calcite-incorporated mixtures.