Concrete, mortar and plaster using titanium dioxide nanoparticles: applications in pollution control, self-cleaning and photo sterilization - Nanotechnology in Eco-efficient Construction - page 314

and Economic Sustainability (BEES) impact assessment model (Lippiat,
2007) was applied to analyse the inventory.
The reduction of the environmental impact of the material was found to
act on four main categories: acidifi cation, eutrophication, air pollutants and
smog formation. Parallel increases in global warming, fossil fuel depletion,
water intake, ozone depletion and impacts on human health were also
assessed, caused mainly by the production phase and fossil energy con-
sumption. Yet, the total environmental performance of the product led to
the conclusion that the titanium dioxide coatings tested have an overall
benefi cial effect on the environment.

13.6 Pilot projects and fi eld tests

The confused mass of information described in the previous sections surely
shows the usefulness of TiO 2 in decreasing environmental pollution, and
more broadly in improving the quality of materials where it is contained.
Nonetheless, it implies at the same time great diffi culties in understanding
the actual behaviour of photocatalytic materials and in classifying them on
the basis of their effi ciencies.
These aspects are probably better investigated through large-scale exper-
imental setups, which are fundamental to defi ne the actual behaviour of
materials modifi ed with titanium dioxide in real practice. In this frame,
Dylla et al. (2010) proposed a new laboratory setup to evaluate the infl u-
ence of various parameters (humidity, pollutant fl ow rate, mix design) on
the effi ciency of photocatalytic coatings for concrete pavements, as well as
on their resistance to abrasion and wear, given the critic application. A
photoreactor with fl uorescent lamps was built with a surrounding circuit
providing the contaminant source (NO) and desired humidity. Particularly
interesting are the dimensions of the photoreactor, 25 cm

2.5 cm,
which allows the evaluation of large samples, up to real-size paving slabs.
Besides large-scale tests, which still belong to the class of laboratory
experiments, higher relevance must be given to pilot projects, as the most
realistic way to measure the working effi ciency directly on site. This is the
scenario from which the project PICADA (Photocatalytic Innovative Cov-
erings Applications for Depollution Assessment) took its fi rst steps. In this
project, a consortium of eight industries and research laboratories was
created, aimed at developing and optimizing industrial formulations of
innovative façade coatings with de-soiling and de-polluting properties
including titanium dioxide, and at establishment of a local behaviour model
under different exposure conditions and in a realistic urban environment.
The biggest pilot test in Europe is probably the 'street canyon' site that
was built in France, near Guerville, in the frame work of the PICADA
project (Guerrini et al. , 2007). The methodology consisted in testing the

× 30 cm ×

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