poured concrete evap

[RI syrup]

Hi all, I was thinking about pouring a concrete wall line it with fire brick, leave a shelf (lip ,ledge) for the pans. A ceramic thimble (hole for smoke stack) and a block out in the front for a door. I can see it I could just use a little advise on what dimensions the masonry guys use. HxWxL thanks in advance. rob

[Teuchtar]

I'd never heard of a poured concrete arch. But one of my early attempts at homemade arch used cast concrete pavers and steps. But after a few days use, those concrete parts had all cracked and were falling apart.
On Wikipedia, they talk about the properties of concrete. Above 300deg C (572 F) they say it will begin to crack. They give all sorts of reasons that only a civil engineer would love to read about.
http://en.wikipedia.org/wiki/Concrete
There's lots of posts here describing the stack temperatures. Firebox temperatures would be hotter still. I think you'd easily get temperatures well above 600 deg F on your arch. The firebrick would shield the concrete from the worst of it, but I believe that high temperature would still penetrate the concrete in a couple of hours of firing.
Maybe there's a high temperature concrete available ? Or skip the poured concrete and use double thickness of firebrick ?
Best of luck with it.

[Sugarmaker]

RI,
Yep poured concrete arch on route 7 south of Conneaut Ohio about 4 miles. Belongs to Dick and Martha Benson, second cousins, has been working well fired with natural gas for years! It will work!

Regards,
Chris

[3rdgen.maple]

We had one of those poured concrete arches on my grandfathers farm. Used it for alot of years with no problems. I think it was like a 3x8. Then he upgraded to a 4x10 with a steel arch. He always said that concrete arch boiled alot better. I would line it with arch board then firebrick, that will keep the heat levels down on that concrete. As far as dimension I would say we need more info. Do you have pans? If so what are the dimensions? One thing I remember on that concrete arch was gramps put angle iron on the edge the pans sit on. The edges were getting beat up. I probably would do that before the concrete dried.

[Haynes Forest Products]

You will need to ancore the angle iron with lags or welded rebar back into the cement. With the cement and steel heating and cooling at differant rates the angle will pop right off. It will curl up and be a nightmare. Rim the arch door with angle also so if it does crack it wont crumbel, I have seen alot of out side BBqs from the 50s that got alot of use that were made from house brick and morter that was lined with fire brick.

[WESTVIRGINIAMAPLER]

Why not just lay up and arch with firebrick laying flat and then if you are concerned about detoriation over time to them, line them on the inside with 1/2 size firebrick on their edge.

[peacemaker]

i always thought of making a stone arch ..

[glassman]

i have a field stone arch i built about four years ago. lined with fire brick it hasnt cracked a bit.

[JohnM]

My arch is concrete block lined with 1" ceramic blanket.

Going on 5 years burning pallet wood, no cracks yet.

[heus]

John M,
What do you have for a base under the mortared cinder blocks?

[JohnM]

I borrowed a mixer and poured about 5 inches of concrete footer before I laid the block.

[Roads End]

WHat about leavign an air gap between the firebrick/ archboard and the cement. Thats a great way of helping to insulate both the firebox and the cement as you no longer have direct conduction between the firebox and the cement shell