GBlist: Hempcrete

["Bion D. Howard" <bdhoward@ix.netcom.com>]

Mr. Tom Cook, Project Director
Slim Butte Land-Use Association

I was glad to receive your press release via an E-mail list. 

One of the historical problems with concrete block has been high conductive
heat flow, resulting in lower R-factors than other building materials.  In
northern climates this is an important energy problem as you know.  Aside
from helping create a more sustainable form of concrete block by including
Hemp fiber in the mix, I believe the resulting block might also have better
resistance to heat flow. 

The hemp fibers can be pretty long which when blended into concrete could
result in better compressive and shear strength in block, and possibly
permitting less quantities of Portland cement to be used to achieve
sufficiently strong masonry units.  This "replacement" or trade off could
apply not only for block but also for paving, curbs, and other pre-cast items.

Hemp compiled into batting material should be a pretty good bulk insulating
material.  Sufficient quantities of the fibers would form insulation
blankets for walls and ceilings that could compete with fiberglass and
cellulose "conventional" insulating systems that can be pretty costly.
Certainly locally produced quantities of "hemp-sulation" (quick, trademark
this name...) might be just an important house building product as your block.

Also, I used to work at the National Concrete Masonry Association (NCMA) in
Virginia.  If your Nation decides to build plants to produce masonry block
for homes and basements, then joining that group might make sense. They can
do various testing that might be needed on the block -- such as to
determine how much added hemp fiber could reduce the amount of cement
(hence cost) in the block, that still meets reasonable strength tests.  I
believe members get access to lots of tech support, and NCMA has engineers
that have studied the "green"-ness of building materials like concrete
versus others.

I would also encourage moisture tests on hempcrete block to see if any
unexpected problems occur before starting to build homes with them.  In
particular does the block crack or swell under cold temperatures in winter
as a result of the Hemp fibers harboring moisture (I don't know?).  This
might happen -- or result in serious cracking and expansion -- only if
larger proportions of fibers are added to the concrete mix.  Some
experiments could be useful.

The NCMA web site might be of interest <http://www.ncma.org>.

Please let me know if we can be of any help looking at the energy
efficiency implications of your plans.  I have studied lots of block
designs to analyze their energy efficiency, including ones with built in
insulation layers of various materials (see: <http://www.cbisinc.com> ).
How about a stable hempcrete block designed to receive a hemp-sulation
insert inside...?  

   Anyway, I appreciate your time reading this note and good luck on your
excellent venture!
  
      <<<  Bion D. Howard

cc:  National Green Building List

======
  -- via --

From: "Maine, Bruce" <bmaine@hdrinc.com>
Subject: GBlist: FW: Hempcrete blocks

> Tom Cook, Project Director
> Slim Butte Land-Use Association
> E-mail: slmbttsag@bbc.net
> 
> On Friday, April 14, Joe American Horse announced on KILI Radio that
> to be sovereign the tribe must act sovereign, so accordingly, he will
> plant industrial hemp seeds on April 29, 2000 to advance the authority
> of the Oglala Sioux Tribe in the matter of jurisdiction over tribal
> lands.
> 
> Stating the USA does not make treaties with ethnic minorities but only
> with other sovereigns, American Horse said he is prepared to exercise
> the self-determination inherent in the Oglala Sioux Tribe as a
> successor government under the Treaty of 1868.

=======


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