We are building a BBQ grill in church (Argentine style, sort of) We wonder if we can use the formula you have for high temp mortar and just put a layer of it on top of a cement slab. (Fire Bricks are way too expensive to cover the slab).
If the above is not a good idea, would regular red bricks work?
If none of the above, what would be an inexpensive way to do it? Basically, we are using cement block that will support a concrete slab array (Each slab 33 x 32 or so) and need to put something on those slabs as we will build the fire on the surface, and distribute embers under the grills.
Thanks for your help!
JC
Hello and welcome to the BrickWood forum!
I applaud the initiative (I’m a certified church guy myself), and…I’m skeptical about whether that would work as you describe it.
I get it about funds, and if what you’re looking for is the glowing embers and flames, you won’t need firebrick for that.
You mention a slab array, which sounds very much like the 3-slab assembly that BWO uses in its hearth designs. I’d suggest this:
- Look at our instructions for casting the concrete slabs, especially the part about using a polystyrene block to create a void in the assembled slabs. That void needs to be the size of your intended cooking surface.
- You will need to put some funds into this. In addition to concrete and the materials for the high temp, you need the polystyrene (foam) insulating sheet, a bag of Portland cement, and a 2 cu yard (not FEET) bag of Perlite. None of those are expensive items.
- Cast your slab array in such a way that you will have an enclosed void when you put them together. Again, see the instructions for the general idea, and adapt it to your dimensions. (For this use, I’m not sure you need the rebar, though rebar also is not terribly expensive. If you can swing it, make a grid whose ends extend just beyond the edges of the void. That will help relieve thermal stress and reduce the chance of cracking.)
- Make the insulating mix of Portland cement and Perlite as described, and pour it into the void leaving about 2 inches from the top surface. Level it and allow it to cure for two days.
- Make the high-temp mortar mix, pour it into the 2-inch void, level with a screed board, and allow to cure for 2 days.
Your first fires will fully cure the high-temp mix rock hard.
This is all based on the idea that you’re not planning to build an oven or any other heavy structure on top of this slab. I’d suggest a clay brick border around the slab to help control air flow and keep burning embers from rolling off the slab.
This definitely feels like MacGyver territory to me, and I’m open to suggestions from the experienced hands on this bulletin board. That being said, I think you’re talking a couple hundred dollars here, and I’m kinda keeping in mind a hope that building this kind of grill might be a gateway to a full-on brick oven in the future. Small starts inspire great ventures!
Please come back if you have questions during your build, and for sure when you’re done to share photos with us.