Civil Engineering Reference
In-Depth Information
Besides self-cleaning cementitious materials, TiO
2
-based self-cleaning
exterior building products including tiles and glass have been widely com-
mercialized and applied. The self-cleaning and stain-free performance are
confi rmed by samples suspended outdoors for six months.
59
For interior tiles
used in washrooms or bathrooms, soilage and dirt are always a problem.
The fatty acids from soap can form chemical bonds with calcium and mag-
nesium in hard water and adhere to the tile surface, which are diffi cult to
clean after the accumulation of dirt. Tiles with a TiO
2
fi lm surface can break
the binding between the organic compounds and the ceramic tiles, which
make the washing process easier. Compared with the other two major
applications, less research work has been conducted in the area of antimi-
crobial building materials. So far, standardized protocols for evaluating the
light-induced anti-bacterial activity have not been established. The stated
effi ciency of different self-disinfecting products cannot be verifi ed and com-
pared. Moreover, effective and reliable coating techniques are needed to
anchor the nano-photocatalysts to interior building surfaces in the event
that the dispersion of fallen nanoparticles causes potential health threats.
14.4 Future trends
The sale of photocatalytic products in the world market began to gain
momentum since 2001 after the successful commercialization of Pilkington
glass. According to the technical market research report (2010), by BCC
Research (35 Walnut Street, Suite 100, Wellesley, MA 02481), the global
market value for photocatalysts is expected to increase to $1.7 billion in
2014, for a fi ve-year compound annual growth rate (CAGR) of 14.3%. BCC
also analysed that the photocatalytic products for the construction sector
currently accounts for the largest share of the market. A need to improve
the photocatalytic anti-bacterial effi ciency is required to implement these
materials in the commodity market. In addition, the potential deterioration
of photocatalytic effi ciency of TiO
2
photocatalysts over time has proven to
be an inherent obstacle for the commercialization of photocatalytic coat-
ings on glass and tiles. Research is currently underway in many universities
and large companies to tackle these problems. The development of highly
effi cient visible light activated photocatalysts has been found to be effective
compared to conventional TiO
2
. The current results on the visible light
induced photocatalysts are promising for further development for tiles and
glasses driven by solar light as a renewable source of energy.
14.5 Acknowledgement
The authors wish to thank Science Foundation Ireland (SFI grant number
10/US/I1822; US-Ireland R&D partnership) funding. The authors would
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