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The economics of earthbags vs. cinder blocks
(CMUs, or Concrete Masonry Units)


Summary
(see links at bottom of page for references)

Empty 14" x 26"
polypropylene  earthbags
Empty 14" x 26"
burlap earthbags
8" x 8" x 16" concrete blocks
Units per 100 lbs: over 1,000
(before filling)
approx. 1000
(before filling)
less than 4
Approximate coverage per 100 lbs: 2583 cubic feet 2583 cubic feet 3 cubic feet
Composition: petroleum-based plastic polymers natural jute or hemp Portland cement, aggregate
Common chemical byproducts in manufacturing: organic compounds
including aldehydes, ox0-alchohols, carboxylic acids
none Mercury, lead, arsenic, cadmium, chromium, molybdenum,  hydrochloric acid, sulfur dioxide, hydrocarbons, ash particulates - released into air, storm drains, and groundwater
Recyclable? yes yes no
Biodegradable? no yes no
Long term impact to environment: UV decomposition can lead to minute airborne distribution of tiny fibers
none Rubble is typically deposited in landfills, leaching chemicals (such as mercury) into soil, groundwater, aquifers & waterways


The cement industry, both nationally and internationally, is under fire & sweating bullets in ways it's never before imagined. 

Starting in 2007, revelations about the industry's "hidden costs" began to receive some wide mainstream reportage & investigation. 

Facts:

  • Portland cement manufacture is responsible for some 5% of CO2 emissions worldwide.

  • Portland cement manufacture is the 4th largest source of mercury contamination in the US.

  • Portland cement kilns are phenomenal energy consumers, needing to be heated to temperatures of 2,700-3,000 degrees Fahrenheit in order to convert raw materials into their end product.

  • Under the auspices of the EPA, many cement manufacturers have been using highly toxic waste to fuel their kilns - the belief being that the high heat destroys or breaks down the toxins & pathogens. Some "reasonable allowances" in excessive emissions have been permitted in a "greater good"rationale.

  • Air emissions from portland cement manufacture (specifically referred to as CKD, or cement kiln dust) contain - besides mercury - hydrocarbons, hydrochloric acid, sulfur dioxide, particulates, and  various heavy metals, including arsenic, lead, chromium, cadmium, and molybdenum.

Meanwhile, water used in the manufacture or portland cement has a pH value of 12 or above, making it phenomenally caustic.
Both unconstrained runoff & incidental seepage enters the soil and sewer lines, and ends up in groundwater, aquifers, and waterways.


In response, the concrete industry in this country has joined forces and formed the “Concrete Sustainability Initiative” – under the auspices of the WBCSD (World Business Council for Sustainable Development).  Comprised of some 200 multinational corporations, it enjoys privileged seats (and major influence) with the World Bank, the WTO (World Trade Organization), the IMF (International Monetary Fund), and the OECD (Organization for Economic Cooperation & Development). 

Members of the WBCSD includes corporations such as Alcoa, Chevron, General Motors, DuPont, 3M, Deutsche Bank, Coca-Cola, Unilever, Gazprom, BP, Wal-Mart and Royal Dutch Shell.

To give the concrete industry credit, they are (after having the writing on the wall read to them) actually making some progress in reducing emissions & releases, and even coming up with some alternative methods & materials (such as using rice hulls) to create “greener” concrete.

However - as is so often the case - real (not token) environmental reform tends to be measured in decades, with a great deal of foot-dragging, court appeals, dithering about the data produced by "our experts" vs. "their experts". In the meantime, the industry continues to  -grow, and their chief sense of responsibility remains to their stockholders - which translates into reducing costs by all feasible means in order to maximize profits.

Despite whatever present or future regulations that domestic concrete may find itself forced to comply with, countries like China & India are still thumbing their noses at the global call for reduction in emissions.  Worse, many Western concrete manufacturers, finding that they can’t keep up with ever-more-stringent regulations at home, are going to Eastern Europe and Russia and the Ukraine,  buying old cement plants for a song, and skirting said regulations.

Where do those $1.00 concrete blocks at Home Depot and Lowe’s come from?

If they’re made domestically, then the true cost must include the impact to our air, our water, our fish & wildlife, our health, and our out-of-control energy consumption (with the result of frantic calls by politicians for more coal-burning & nuclear power plants).

On the other hand, if these "big box" concrete blocks are made overseas, then their true cost is the impact to the environment and the  infrastructure that impacts the people of the countries in which they're made, plus immense transportation costs to ship them to American ports and then truck them over American highways (more pollution)... notwithstanding that they may contain materials not sanctioned for domestic manufacturers.

Where do cinder blocks go when they die? Broken into rubble, they're dumped in solid waste landfills all around America (landfills themselves facing a crisis), where mercury and other contaminants are leached into water tables (our drinking water) and streams. For a disturbing look at some of the causes behind the epidemic rise in breast cancer, click here.

We think earthbags make a lot more sense. While the polypropylene bags are admittedly made of petroleum-based plastic polymers, the amount used per bag is modest, and (if not plastered over) they are recylable (Resin Identification Code 5). Burlap bags are fully biodegradable.  In terms of mass, 1,000 empty polypropylene bags (at about 85 lbs, capable of building approx. 2,583 cubic feet) weigh less than three 8"x8"x16" cinder blocks (at about 90 lbs, capable of building approx. 1.8 cubic feet) . 

While both poly & burlap bags are sourced from Asia, and carry a carbon footprint based on manufacture and transportation to North America, this too is negligible by comparison. The only way to improve on polypropylene earthbags as a modular construction component is to hope for the development affordable vegetable-based polymers (pending), to use burlap or hemp bags, or to forego using bags altogether & use adobe bricks or rammed-earth construction.



Some links:

http://www.epa.gov/region8/superfund/ut/portlandcement/ 

http://www.epa.gov/osw/nonhaz/industrial/special/ckd/index.htm
http://www.greenbiz.com/news/2009/06/17/proposed-epa-cement-kiln-regs

http://www.nytimes.com/2007/10/26/business/worldbusiness/26cement.html
http://www.voanews.com/english/Science/2009-07-02-voa39.cfm
http://en.wikipedia.org/wiki/Portland_cement
http://en.wikipedia.org/wiki/Polypropylene
http://en.wikipedia.org/wiki/World_Business_Council_for_Sustainable_Development
http://archive.greenpeace.org/toxics/documents/altdetoxCement.pdf


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