Building in Sudan with Limited materials

[maxsbarandgrill]

This thread was in Newbie side but someone suggested I move it here. I have pretty much completed my oven by following some of the directions of members. I made a steel barrel type oven. I then put mesh, a layer of concrete with stones. The ratio was about 1:1:1/2:6 , Portland, river sand, lime, stones. I read that somewhere in the forum but can't find it now. It was REALLY heavy duty, hope it is okay. I then put a layer of red brick, then thermal blanket, then 2 layers of 1:5 Portland and sand. I would love opinions of how this will hold up and how best to cure. Should I let all this sit for a few days? I have read a week is best but being steel lined barrel type, is it different curing process? I am trying to get my restaurant open and am in a rush but don't want to destroy the work of course! Advice welcome.

[LittleBritaly]

Re: Building in Sudan with Limited materials

You'll*probably find that the cement will crack, you should have mixed fireclay in with the portland/lime/sand.

Watch out for it actually exploding, this happens when you fire the oven with the cement not totally dried out, the trapped water turns to steam, has nowhere to go, something has to give. Guess how I know.

I now put some gently heat into all my oven straight from the start, I just light a couple of candles and keep them burning all day.

I would give your oven a little mass, cover the inside with refractory mix (email/pm me if you want the ratios for the mix).

Your oven will work, to a greater or lesser degree, if it doesn't work as you hoped just post back you'll find plenty of experienced folks who will be able to give you a solution.

[david s]

Re: Building in Sudan with Limited materials

You should drive out the water before doing the outer shell. That way it has a chance to escape. If the water is trapped inside it is more difficult to remove.As you've already done it, you should leave it for a week before drying it out.It won't really matter if the heavy concrete and bricks crack a bit because they are held captive between the steel barrel and the outer shell. Sounds like you have a lot of added thermal mass. It may take a long time to heat up properly. Did you insulate under the floor?
Fire slowly and try throwing some plastic over the top of the oven. Condensation on its under side will tell you if there is moisture still present.

[maxsbarandgrill]

Re: Building in Sudan with Limited materials

Thank you. I did notice sort of a hollow sound on the sides where hot gases or steam might cause a problem. I built a few small fires and saw wet spots form, moisture obviously escaping and drying out. I think it dried almost completely and have now started layering mud and manure as the locals do here. I hope it works. When I tried to get the oven temp up previously there was cracking and too much heat escaping, the highest temp I achieved was about 300F. Do you think it will be safe with the outer mud/manure layers now? My ceiling height is about 27 inches...maybe too high for good heat? Any advice appreciated.

[david s]

Re: Building in Sudan with Limited materials

Like I said before you should drive out the water before adding anything over the top, otherwise you are just making it more difficult to remove.How thick are your walls between the blanket and the steel barrel? With all that wet concrete and mud it must be say 100 litres at a guess. Half of that may be taken up in the hydration process as the concrete cures so you are still left with a large volume of water to eliminate. The water will hold the temperatur of the oven down and extra fuel is required to convert it to water vapour. A couple of candles burning in that oven won't evaporate much water. You will need lots of long slow fires.
Is there any insulation under the floor?