parko
New Member
Posts: 2
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Post by parko on Aug 20, 2014 21:06:05 GMT -8
For the past couple weeks I'e been making a mold for a rocket stove (here). My problem now is finding a concrete that will be really strong, so I can move the stove around occasionally and not have it break, but also be heat resistant. It's a bit of an experiment and I haven't found a great resource talking about practical instructions for ideal high temp concrete. At the moment I'm using Istra 40 cement, which I think I added too much water in my first attempt. It's kinda difficult to find good info here, as usually people use fire bricks, but I just was wanting to cast the whole thing in a single pour. This may prove too difficult, but I haven't given up yet...
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Post by Dan (Upstate NY, USA) on Aug 22, 2014 0:55:34 GMT -8
Concrete that is strong enough to move in non-refractory situations is held together with rebar (steel reinforced bars).
If you use rebar in a stove it will expand quicker than the concrete and it will all fall apart under high temperatures.
You would have to do at least a two part mold, one for the heat riser and one for the lower box.
You also need a some kind of vibrator to get all the air out of your mold.
You are trying to run before you learn how to walk. Have you built a rocket stove out of bricks and had that run properly yet?
-Good luck and keep learning...
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parko
New Member
Posts: 2
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Post by parko on Aug 24, 2014 5:47:38 GMT -8
Thanks, appreciate the advice. I'll take that into account, might modify it to be two parts, which would be better for insulation and repairability. Yep I actually tried a lawnmower as a vibrator, but as in the photos that was a complete fail. I'm thinking now that I'll build the mould as I pour it, which hopefully will solve any problems with filling any gaps.. cheers for that
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