Civil Engineering Reference
In-Depth Information
13
Concrete, mortar and plaster using titanium
dioxide nanoparticles: applications in pollution
control, self-cleaning and photo sterilization
M. VITTORIA DIAMANTI and M. P. PEDEFERRI,
Politecnico di Milano, Italy
DOI
: 10.1533/9780857098832.3.299
Abstract
: Many advances have been made in understanding the
mechanisms of TiO
2
photoactivity and in developing its potential in
addressing environmental issues. This chapter provides a short overview
of these mechanisms, focusing on construction materials (mortar,
plaster, concrete) modifi ed through the addition of titanium dioxide
nanoparticles. Examples will be given of laboratory experiments carried
out in recent years, and of current applications in the built environment;
attention will also be paid to the international standards that have been,
and are still being, developed for this technology.
Key words
: titanium dioxide, photocatalytic cement, self-cleaning,
material ageing.
13.1 Introduction
TiO
2
has been used for centuries as white pigment in textiles and paints,
well before the discovery of its photocatalytic properties. Curiously, altera-
tions induced by TiO
2
pigments in supporting materials (degradation of
paints and fabrics, or bleaching of dyes) had already been observed, but not
understood. It was only in twentieth century that these alterations could be
related to its photoactivation. The following list summarizes advances in
research in the last 100 years in understanding mechanisms of TiO
2
photo-
activation, and in developing and optimizing its properties:
• The fi rst trace of scientifi c works on this subject is a paper published by
Keidel in 1929, suggesting an active role of TiO
2
in the fading of paints.
•
In 1938 the photobleaching of dyes caused by UV-irradiated TiO
2
was
investigated by Goodeve and Kitchener, and ascribed to the presence
of active oxygen species detected on TiO
2
surfaces.
•
In 1964 Doerffl er and Hauffe fi rst proposed a research paper whose title
contained the term 'heterogeneous photocatalysis': zinc oxide was used
as photocatalyst.
299
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