Transcript Lightweight Concrete – An International Perspective

Design of Appropriately
Constructed Facilities to
Cope With Global Warming
By
Ted Bremner
Professor Emeritus & Honorary Research Professor
University of New Brunswick, Fredericton, NB,
Canada
Prague October 2012
Current best estimates forecast
only minor warming in the
equatorial regions including India
while large temperature rises are
now occurring in the polar regions.
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NOTE: India has very low surface
temperature increase between 1976
and 2001.
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Warming World
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The cumulative effects of our past
and present action have set in play
dynamic forces that will destroy
the planet unless we act in a more
decisive way. Simply to stop
peddling on a bicycle going down
a progressively more steep hill will
not avert disaster.
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There are many examples of this with
perhaps the most serious in the Arctic
where the organic rich permafrost is
thawing, and their decay will cause
release of green house gases that in
turn cause global warming. If not now,
eventually the process becomes self
sustaining without input from us.
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To avert disaster, global warming caused mainly
by greenhouse gases must be reduced
everywhere in all possible ways. Excessive
behavior of humans is the main cause but
fortunately people can change their ways quickly,
as witness:
USSR morphing into separate countries.
Reduction of acid rain in eastern North
America.
Elimination of DDT in Canada in 1957.
Elimination of lead in gasoline in Canada
and the US.
Mandating sustainable forest usage in most
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of the world.
As producers of construction materials we have:
1. Reduced carbon dioxide emission from
cement manufacture by up to 50% by
replacing cement with fly ash, slag and silica
fume.
2. Recycled metals with 60% of steel being
made from scrap.
3. Perfected the art of recycled asphalt.
4. Through the use of insulation and green
roofs reduced the energy required for
heating and cooling buildings.
5. Developed an accounting procedure to
evaluate the carbon foot print of our
constructed facilities.
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Unfortunately, as designers of
constructed facilities, we have
not come up with new design
concepts that reflect the needs of
a world under stress. This
includes strategies to cope with
rising sea levels and to provide
affordable housing and effective
public transportation.
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A Canadian cement company had this slogan
bravely stated in bold red letters on the bottom
of its correspondence, “CONCRETE FOR
PERMANENCE”. In the 1960s the use of air
entrainment with a high enough cement
content and a low water content was intended
to assure customers that the concrete would
be durable for eternity. Unfortunately alkali
aggregate reaction, delayed ettringite formation
and corrosion of embedded reinforcement
shortly led to the removal of the slogan.
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Veigh, in his book “Conception of the
Theory of Environmentally Compatible
Structures and Structural Materials (ECS)”,
emphasizes the need to rethink how most
buildings are constructed, and stresses what
can be learned from nature. Surface
structures rather than post and beam
structures clearly make the most effective
use of our new materials. Also, if trends in
the cost of energy continue, then solutions
to global warming problems will need more
complex structures.
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The first step is to realize that
affordability is of prime concern to
avoid a U.S. housing crisis type
problem. Recent advances in the
use of foam and cellular concrete
indicate that this relatively mature
technology can be used for lowcost housing, although it is
considerably underutilized at the
present time.
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The term “Environmentally Compatible
Structures” encompasses both the risk from
the materials and the risk posed by the
structure itself. In the case of materials there
is a well-developed understanding of the
need to guard against the use of hazardous
materials such as asbestos, arsenic and
mercury from the combustion of coal. Less
well appreciated are the hazards associated
with the short and long term effects of
effluents created by the mining industry.
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In places where rising sea levels and storm
surges are likely to occur, retreating in an
orderly manner seems the only practical
approach. A report prepared for the
Canadian Department of the Environment by
the Round Table on Climate Change
(Report No, 4) indicates a strong preference
for this approach (6). This study found that
building dykes to hold back the sea was
highly uneconomical and totally impractical,
if not impossible, in many threatened sites.
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In the past two decades the type of
constructed facilities needed by the
military has changed somewhat as we
go from multi-national wars to national
wars. An example of recycling military
discards is in Moscow where an
abandoned inter-continental missile silo
became the foundation for a very large
vibrating table for research on
earthquake resistance of high-rise
buildings, but this is still an exception.
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In both developed and developing
countries there is a need to recognize the
fragility of the situation. In the developing
world, changes need to be made to
alleviate financial crises that inevitably
must result in more economical and more
appropriate housing and public facilities.
In North America and in most of the
developed world we have built
extravagantly, and now smaller and more
modest housing is necessary.
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The level of funding needed to solve
the problems associated with global
warming on a government, industrial
and individual basis is likely to be
unavailable. Those of us involved in
providing solutions must manage to do
business in a cost-conscious and more
stressed world, while at the same time
producing more appropriate
constructed facilities.
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Setting National Limits
Kyoto Protocol (2008) Most Nations commit to
limits on greenhouse gas emissions.
Durban Negotiations (2011) China and India can
avoid any legal limits on their fast-rising carbon
emissions. European Countries make progress but
USA and Canada renig.
??? Protocol (2015) Negotiation of rules for
greenhouse gas emissions.
??? (2020) Negotiated rules will come into effect.
Global Warming (2030) will have exceeded the
tipping point for maintaining a sustainable Planet.
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Country CO2 Emission
per person in
109 Tonnes
Quitar
USA
Canada
China
Ecuador
Brazil
India
1990
25.2
19.1
16.2
2.2
1.6
1.4
0.8
2008
53.5
19.5
16.4
6.8
2.2
1.9
1.4
% of
World
Share
Rank
per
Person
2008
0.2
18.1
1.8
23.3
0.1
1.3
5.8
1
12
15
78
120
124
145
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Solution
It is apparent from the previous table that there
is no solution to global warming unless the USA
and China recognize that they must take the
lead in reducing it. Global warming and
scarcity of water are interrelated and these two
countries apparently are not now sufficiently
concerned to commit to change.
For change to occur nations immediately must
come together to share water resources.
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Conclusion
Recent advances in construction
materials have been such that
greater usefulness can be expected,
and those who are designing facilities
need to make more effective use of
what is available.
[email protected]
http://www.unb.ca/fredericton/engineering/d
epts/civil/people/bremner.html
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