Civil Engineering Reference
In-Depth Information
that increasing its durability from 50 to 500 years would mean a reduction
of its environmental impact by a factor of 10. The importance of concrete
durability for their eco-efficiency has also recently been recognized by
other authors (Flatt et al., 2012). concrete structures with low durability
require frequent maintenance and conservation operations or even integral
replacement, being associated with the consumption of raw materials and
energy. concrete durability means, above all, minimizing the possibility
of aggressive elements entering the concrete, under certain environmental
conditions, for any of the following transport mechanisms: permeability,
diffusion or capillarity.
The use of concrete surface treatments with waterproofing materials
(also known as sealers) to prevent the access of aggressive substances is
a common way of contributing to concrete durability. however, the most
common surface treatments use organic polymers (epoxy, siloxane, acrylics
and polyurethanes) all of which have some degree of toxicity. Polyurethane is
obtained from the isocyanates, known worldwide for their tragic association
with the bhopal disaster. The production of polyurethane also involves the
production of toxic substances such as phenol and chlorofluorocarbons.
besides, chlorine is associated with the production of dioxins and furans
that are extremely toxic and also bio-cumulative. Several scientist groups
already suggest that chlorine industrial-based products should be prohibited
(Pacheco-Torgal and Jalali, 2011a).
recently, the european Union approved the regulation (eU) 305/2011
related to the construction Products regulation (cPr) that will replace the
current Directive 89/106/cee, already amended by Directive 1993/68/eec,
known as the construction Products Directive (cPD). a crucial aspect of
the new regulation relates to the information regarding hazardous substances
(Pacheco-Torgal et al., 2012). new low-toxicity materials and techniques
that increase concrete durability are therefore needed. an innovative
approach to solve this and other current technological problems faced by
human society which can encompass a new way of perceiving the potential
of natural systems (Martin et al., 2010). The continuous improvement
of these systems carried out over millions of years has been leading to
materials and 'technologies' with exceptional performance and that are fully
biodegradable.
recent nanotechnology achievements regarding the replication of natural
systems may provide a solution to solve the aforementioned problem (Wegner
et al., 2005; Pacheco-Torgal and Jalali, 2011b). analysis of bioinspired
materials requires knowledge of both biological and engineering principles,
thus constituting a new research area that can be termed biotechnology.
although this area has rapidly emerged at the forefront of materials research,
the fact is that the study of biological systems as structures dates back to the
early part of the twentieth century with the work of D'arcy W. Thompson,
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