Is Concrete a Green Building Material

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					Is Concrete a Green Building Material?



  The Emergy and Environmental Impact…
 What is Emergy?
•Phrase originally coined by Professor
Howard T. Odom in 1986
•“Emergy can be defined as the total solar
equivalent available energy of one form
that was used up and directly and
indirectly in the work of making a product
or service.” (Odom, 1996)
•Measured by scientific unit “Emjoule”
•“Embodied Energy,” established as a
means to understand and evaluate the
energy involved in the production and
destruction of a particular material…
Concrete Production
•   Patented in England by Joseph
    Aspdin in 1824, resembled Isle of
    Portland quarried Stone
•   75- 90 million tons of Concrete
    production per year in the last
    decade… (Portland Cement Ass.)
•   Cement production involves the
    mixture of Limestone, clay/sand,
    bauxite, iron ore in a rotary cement
    kiln:
    –    Kiln rotates slowly mixing contents
         progressively getting hotter to reach
         temperatures up to 2700°
    –    Largest piece of moving industrial
         equipment in the world

•   Concrete is made up of:
    1.   Portland Cement 12%
    2.   Sand 34%
    3.   Crushed Stone 48%
    4.   Water 6%
          Emergy Efficiency
• It takes 2,300 to 3,500 pounds of raw materials to produce
one ton (2,000#) of cement.
• Cement is the most energy intensive component of concrete
and all industrial manufacturing processes, 92% of emergy in
concrete
•Cement production takes about six million BTus for every ton
of cement; includes direct fuel for mining and transporting raw
materials…
             Pro’s of Concrete
• Creates sustainable Sites
• Enhances energy performance
• Contains recycled material (fly-ash, slag
cement, etc.)
• Cement kiln burn hazardous waste
materials as fuel; high temp = complete
combustion and decrease pollution…
• Manufactured Locally
• Builds durable structures
• LEED Certified as Green building
material
• Utilizing concrete in commercial
buildings offers up to 25 certification
points.
          Con’s of Concrete
• Concrete accounts for up to 67% by weight, 53% by volume of
C&D Solid Waste…and only 5% avg. is recycled!
•¾ Tons of C02 per ton of cement in the combustion of fossil fuel
•Additional CO2 released in calcining; turning limestone into lime
•Dust & Air pollution via Kiln; manufacturing, transportation, etc
•H2O pollution as high PH or Alkaline water toxic to marine
wildlife…
•New add-mixtures increase chemicals within concrete to
control; setting time, plasticity, pump-ability, water content,
strength, and color.
•Despite the Alkalinity when wet, traditionally concrete is very
safe and chem free…
Solutions and Recommendations
    •Fly-Ash; reduce solid waste and reduce
    overall energy use as cement substitute
       –Increase concrete strength
       –Improve sulfate resistance
       –Decrease permeability
       –Increase overall workability of concrete
    •Increase waste fuel used by Kiln; 50%
    •Switch to lower CO2 fuels; Natural gas
    and Ag. Waste
    •Utilize Pre-cast concrete structures to
    reduce dust and H20 pollution…
    •Minimize the amount of concrete use by
    buildings and focus on the strategic use
    of the material to provide maximum
    structural support and minimal
    environmental degradation…
                    Sources
•http://www.buildinggreen.com
•“eMergy Evaluation” Howard T. Odom,
Environmental Engineering Sciences,
University of Florida, Gainsville. May 27,
1998.
•http://en.wikipedia.org/wiki/Emergy
•http://www.cement.org/buildings/gree
n_leed.asp
•http://www.usgbc.org/
•“Emergy indices and ratios for
sustainable material cycles and recycle
options” M.T. Brown, Vorasun
Buranakarn, July 2002.

				
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