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GSBN: Digest for 6/24/02

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-> More from Kelly about China
     by Paul Lacinski paul@...


Date: 24 Jun 2002 20:27:00 -0500
From: Paul Lacinski paul@...
Subject: More from Kelly about China

Following is the full text of Kelly's message, which includes the 
piece about flyash:

>Hi all,
>Here I am running around northeastern China. 340 houses in 4 
>provinces this year and all is going well. There are couple of 
>technical issues here that I'd like to bring to the community 
>The first issue is relatively benign, just interesting. We finally 
>have some excellent monitoring data from last winter comparing 
>straw-bale houses and brick houses. The data was collected by the 
>Chinese Centre for Environmentally Sound Technology Transfer 
>(CESTT). They monitored 25 houses (half brick, half SB) using HOBO 
>data loggers for temperature and relative humidity as well as 
>measuring fuel use (both coal and crop residue). The data clearly 
>shows that straw-bale houses are 64 -68% more fuel efficient 
>(MJ/day) than their brick neighbors (not surprising, but still very 
>gratifying). They also observed that the relative humidity (RH) in 
>the straw-bale houses (SBH) is about 10% higher than in the brick 
>houses (RH in SB 61%, RH in BH 51%). The RH of the SHB is much 
>closer to the outdoor RH of 66.5%.
>I'm postulating that the straw bale walls are more vapor permeable 
>than the brick walls and thus the interior RH follow the exterior RH 
>humidity more closely. It may also be that thicker plaster on the 
>straw bale walls (compared to brick walls) is acting as a moisture 
>sink and working to balance the RH between times of high RH and low 
>RH. Any other thoughts??
>FYI, the whole report will be available in early July and CESTT 
>would like to present it at some technical, architectural and/or 
>sustainable development conferences. Any suggestions?
>The second issue has to do with plaster. Paul Lacinski and I have 
>been experimenting with plaster mixes here in China using locally 
>available materials. Last year we used flyash in several mixes (both 
>with lime and with cement). I won't go into the detailed mixes, but 
>do any of you have a feeling for the effects of flyash in plaster? 
>Clearly flyash is a pozzolanic material, and in concrete it adds 
>compressive strength and decreases workability. I'm wondering if it 
>also (like cement) makes the plaster less vapor permeable. Does 
>anyone have experience using flyash in lime plasters? There are 
>actually two types of flyash here - one is fine and powdery (very 
>similar to cement) and the other is rough and irregular, up to 3mm 
>diameter. We've used both types. The rough type is actually more 
>like an aggregate though it does seem to have a very weak pozzolanic 
>reaction. Any thoughts on flyash and permeability or suitability for 
>Kelly Lerner
>One World Design
>Kelly Lerner
>One World Design

- -- 
Paul Lacinski
Amy Klippenstein
GreenSpace Collaborative
Sidehill Farm
PO Box 107
463 Main St.
Ashfield, MA 01330 USA


End of Digest

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