Civil Engineering Reference
In-Depth Information
The most vital step to ensure exposure prevention is an accurate assess-
ment of potential chemical or physical reactions that may occur during the
lifecycle of the MNM. In other words, it is the responsibility of the manu-
facturing and construction industries to prevent any transformations of the
MNM so that the creation of hazardous byproducts can be avoided. In
addition, it is undesirable to incidentally modify the unique properties of
the MNMs being used since this will likely make them behave less effi -
ciently than design has intended, and perhaps cause more adverse structural
or health effects than if they were not incorporated at all.
Since there are many factors involved in determining the relationships
between the structure and the MNM, thorough physicochemical studies
should be made by the manufacturer during the development process to
identify any unfavorable conditions and reactions. Here, the fate, behavior,
and environmental reactions such as adsorption and desorption, particle
aggregation, reduction-oxidation reactions, deposition, or ion dissolution
should be investigated for each MNM. Similarly, the construction compa-
nies using these new materials should consider the fi ndings provided by the
manufacturer and determine the safest way to incorporate the MNMs into
the structure without taking away from their desired benefi ts. This may
include encapsulation or coatings to reduce dangerous interactions with
other structural components. Contractors should also consider minimizing
the amount of MNMs used in a project when one material may do the work
of many. It may be safer to use the same MNM for a variety of purposes
than to use a different MNM for each purpose so that potential damaging
reactions may be minimized and an increase in adverse health effects is
kept low.
7.3.2 Useful life of the structure
Throughout the use of the structure, MNMs may still be released even when
proper construction practices have been used. Unanticipated environmen-
tal conditions, weather phenomena, vandalizing, and wear and tear can
cause cracks to form, paint to peel, and internal structural components to
be exposed. When such damage occurs, MNMs may be released into the
environment to be taken up by users via inhalation or ingestion, or they
may be chemically/physically transformed by new unfavorable conditions.
In addition to allowing MNMs to release from the construction, structural
fl aws also permit water and other reactants to enter through openings to
transform the MNMs. Depending on the material used, hazardous byprod-
ucts may be created or unveiled, reducing the usefulness of the
nanomaterial.
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