#11  
Old 08-30-2009, 10:54 PM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

Hi Jamie,

More good info. You do make me feel a little silly that I didn't think of filling in the circular base wall with rubble and pouring the support slab on that--I could have saved a lot of work! If I can't move the slab, I'll use your technique to pour another one. I can't imagine this one breaking though maybe if it got dropped.... I did build in a bunch of wire handles to help in moving the slab, but I don't think I appreciated how HEAVY it is--it takes 8 people to drag the slab. We'll see how today goes. I have a local friend who will be heading todays lifting effort--it is pretty amazing what people here can accomplish using low-tech methods, homemade pulleys, group efforts etc. He thinks they can do it.

In addition to the reeds, I have a bunch of drying grass which is similar to straw--I think that mixed with clay soil would be a good coat of insulation surrounding the local bricks to make the oven. I had thought the straw would burn up, but I guess in the mud clay despite the heat it wouldn't get enough oxygen to burn. Sounds workable.

I appreciate everyone's help--great ideas!

UPDATE: Got the support slab up on the brick circular wall. Ten strong guys, about 10 minutes work and done before 10 a.m. No problems, no injuries It is a good thing I built wire handles into the slab--that was a big help.
--Janine

Last edited by Janine M. LeGrand; 08-31-2009 at 01:31 AM. Reason: Update--more information
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  #12  
Old 08-31-2009, 04:12 AM
Il Pizzaiolo
 
Join Date: Mar 2009
Location: USA
Posts: 1,436
Default Re: Hello from Uganda

Hi Janine,
I admire your determination, You are certainly putting forth enough effort. You said you do have access to cement, Is it portland cement or is it a redi mix like quikcrete ? Are you so far out in the country you can not have things shipped to you ? Or is it just too expensive to have things shipped to you ? Keep Going Strong......
Mark
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  #13  
Old 08-31-2009, 06:37 AM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

Hi Mark,
I appreciate the encouragement. The cement here is not a ready-mix. The bag is labled "Multipurpose Cement for General Application" and " Pozzolanic Cement US EAS 18-1:2001 CEM IV/B(P) 32,5 N" which is pretty much greek to me but I assume it is Portland cement. You have to mix with sand and/or gravel. A 50 kg bag runs about $15 US here in this town. I also have seen lime available locally though I haven't bought any yet.

I am about 3-4 hours north of Kampala (the capital) where you can get many more things but transport is an issue. I get around locally here by a small motorcycle, but to go to Kampala I take a public bus or, if I can, I get a ride with a friend. It isn't exactly easy to bring back heavy items. It is possible to hire a large truck, but I haven't done it and it is complicated and expensive. Complications include things like no street addresses here. Having things sent from the US is of course expensive (say $50 for an average size box and it takes 1-2 months for Priority (despite what they say in the US post offices.) I don't have valuable things mailed as there is a chance they won't arrive.

Its a bit of a challenge living here, but very interesting.

--Janine
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  #14  
Old 08-31-2009, 09:25 AM
cynon767's Avatar
Apprentice
 
Join Date: Dec 2008
Location: Sacramento, California
Posts: 230
Default Re: Hello from Uganda

The straw, being a hollow linear fibrous tube, is mostly air. That's what makes it both a good insulator and a strong building material; it turns a dense sticky material like clay or mud into a porous matrix of tiny tubes and interwoven fibers. It's the original high-tech composite material!

The fact that the individual lengths of straw are isolated from the outside air supposedly keeps them from burning out. The ones that char still provide insulation; even if they burned out completely they would still leave behind the airspaces in the clay which do the job of insulating.

I have not used the material myself, but have read that short (2-3 inch) chopped lengths of straw work best, mixed into a slightly sandy mix of clay/mud.

I'm glad to hear the lifting operation was successful!
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  #15  
Old 08-31-2009, 04:50 PM
Il Pizzaiolo
 
Join Date: Mar 2009
Location: USA
Posts: 1,436
Default Re: Hello from Uganda

Hi Janine,
I looked up Pozzolanic cement and found this:

The Pozzolanic cements are comprised of fly ash or volcanic ash and a chemical binder. This combination produces a very dense matrix that has a slight porosity, thereby dramatically reducing the material’s susceptibility to gas and liquid intrusion thereby making it a more durable repair material.

If this stuff is made with volcanic ash it might have some kind of heat resistance ? I guess you might have to do some more research, Google It... It has a lot of good qualities it may be what you need..
Mark
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  #16  
Old 08-31-2009, 10:32 PM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

Hi Jamie,
Thanks for the explaination on why straw works as an insulator and the details on the desired mix. I think I will put down a layer of straw/clay under the oven. Also over the bricks of the dome of course. For under the oven, I could 1.) keep the straw/clay mix to the interior of the brick circle or I could 2.) extend the straw/clay under the wall bricks of the dome. Option 1 would not provide as much insulation as heat in the wall bricks would move down into the slab. However, option 2 might have a concern about settling. With option 2, the weight of the dome would be on the straw/clay and if the straw in the clay rots out or burns then I wonder about the structural strength of the clay with all the airspace. I wouldn't want to build the dome then have a section of it drop down one or two inches if the straw/clay collapsed. I am leaning towards option 1 keeping the straw/clay inside the oven circle for the floor build with the wall bricks resting directly on the concrete support slab. What do you think would be the better plan? Or, do you have a different suggestion?

--Janine
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  #17  
Old 08-31-2009, 11:51 PM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

I think I figured out how to show you pictures of the stand so far so you can see what I have done so far. The stand is a bit rough but should be functional. We ended up building putting up the circular brick wall at night by flashlight which probably wasn't the best idea but I think it will work. The concrete support slab was made first sitting on a bunch of grass on the foundation--the foundation was a good flat area so I used that. I built in wire handles in the support slab to help in moving it. After the slab was a bit cured it was dragged off the foundation so we could put up the wall around the firewood storage area. Then 10 strong guys lifted it onto the wall. The handles on the support slab will be covered in the oven build.
---Janine



Added comment: Oops, the photos aren't showing here on my computer. The next post has the photos--took me a little bit to figure out how to post them.

Last edited by Janine M. LeGrand; 09-01-2009 at 12:25 AM. Reason: Trying to get photos to show
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  #18  
Old 09-01-2009, 12:20 AM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

Hello from Uganda-oven-stand1smlfile.jpg
Hello from Uganda-oven-stand2smlfile.jpg

OK, second try at the pictures--think this should work.
--Janine
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  #19  
Old 09-01-2009, 05:33 AM
Rodneyf's Avatar
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Join Date: Mar 2009
Location: Sydney Australia
Posts: 148
Default Re: Hello from Uganda

This build is going to be one for the books so please keep the pics coming and there will be a lot of us keeping watch.
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  #20  
Old 09-01-2009, 06:21 AM
Peasant
 
Join Date: Jul 2009
Location: Masindi, Uganda
Posts: 48
Default Re: Hello from Uganda

Hi Rodneyf,
I tried to get pics of all the guys moving the slab, but unfortunately some of them didn't want me to take photos. Here people can be sensitive about having their photos taken so no photos of that. It was pretty amazing--that slab was HEAVY and they took care of the job in a few minutes. I'll plan to keep adding photos.

Thought you might like to see the kind of bricks I am working with. They vary a fair bit in size and break pretty easily but are the standard building material around here. The way to cut them is to use a machete.

--Janine
Hello from Uganda-ugandan-bricks-smlfile.jpg
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