Mini Portable Beginnings

[asudavew]

Re: Mini Portable Beginnings

I've thought about building one of these.

A good idea might be to wrap the dome with chicken wire after completion and cover the chicken wire with high heat mortar.

Kind of like rebar in concrete.
Get half the mortar under the chicken wire and half over the top.

[sbinder]

Re: Mini Portable Beginnings

I like the way you think. I had also thought about the chicken wire in the mortar but was worried about the different expansion coefficients. I was wondering if it would be better to embed the chicken wire in the first 1/2 inch of vermiculite that covers the dome. It could still provide stability but be less affected by the heat.

[rroughtrade]

Re: Mini Portable Beginnings

For the relative thickness of the chicken wire, I wouldn't think that you would have to worry so much about expansion co-efficients. The chicken wire would act like rebar and provide much needed support to the mortar. My main concern with a portable unit would be keeping everything from falling apart when I was moving it.

[asudavew]

Re: Mini Portable Beginnings

I think it would be much stronger in mortar.
Vermiculite cement isn't very tough

[david s]

Re: Mini Portable Beginnings

I covered my portable oven with one inch (trying to keep the weight down) of refractory concrete. My brew was 4:3:1:1:1 1/4"aggregate,sand,lime,portland cement, fire clay. I also reinforced with the small sized chicken wire, lots of short overlapping pieces.The oven is holding together well, but I hate unsealed roads.

[david s]

Re: Mini Portable Beginnings

The reason steel and concrete work well together is because they expand at the same rate. The high temp may cause problems with the zinc coating on galv. Try using stainless steel reinforcing needles as an alternative.

[thecac]

Re: Mini Portable Beginnings

Hey sbinder. do you have an estimate of the weight of the finished unit?

[sbinder]

Re: Mini Portable Beginnings

I don't have an estimate. I'm guessing somewhere around 3,000 lb but that is just a wild guess. My base is 800 lb already and then with another 1500 lbs of brick...

[sbinder]

Re: Mini Portable Beginnings

David,

Thanks for the feedback on the reinforcement ideas. I had talked to a guy that sells the SS pins and he didn't feel that it would help very much. I do like the idea of the chicken wire and plan to go with that approach, especially since you have already proven that it will work.

[david s]

Re: Mini Portable Beginnings

Binder,
The brew I refered to was over the inner dome. On the outer shell I used a 4:1:1 sand/ lime Portland cement render and again used fine chicken wire of overlapping pieces. This shell is only 10mm thick. Again I was concerned to keep the weight down. This outer shell is like a ferrocement boat. I read somewhere that if you want it stronger you use more mesh rather than more cement. The shell is finished with about 2mm of acrylic render, but this should only be applied after ALL moisture has been eliminated.Hope this helps.

[sbinder]

Re: Mini Portable Beginnings

Well I have the first two rows done and started on the third. Slow but sure.

[sbinder]

Re: Mini Portable Beginnings

A little more progress to report. Soon I will be ready to go over the doorway. I'm also making plans for the 6" SuperVent Chimney.

[sbinder]

Re: Mini Portable Beginnings

I thought it was time to add a couple more pictures. This is going slow but sure. I'm happy because the next row will go all the way around instead of having to stop for the door.

[sbinder]

Re: Mini Portable Beginnings

I've got a few more rows added. I think I will wait to add the rest of the fill in morter until I can add chicken wire in for reinforcement as has been suggested by various members of this forum.

[PeterW]

Re: Mini Portable Beginnings

The reason steel and concrete work well together is because they expand at the same rate. The high temp may cause problems with the zinc coating on galv. Try using stainless steel reinforcing needles as an alternative.

Another alternative is to use glass fibre reinforcing - its a bit like chopped strand mat without the binder, and is just blended through the mortar mix.

Cheers

Pete