Bricks for 42" Oven - Question about Refractory Bricks

[wthwaites]

Based on my research, Magnesium Chrome bricks have a density figure that doubles the bricks I have...

[wthwaites]

No, I highly doubt that I can.
Like I said in my first post, I got them from a cement manufacturing plant as they were being disposed of.
I have no idea what hexavalent chromium is...Should I be concerned???

[Petter]

I think he refers to the risk of forming hexavalent Chromium during heating if so.

Do you have a way of getting your bricks analyzed?

[wthwaites]

Have you used any of those black bricks? They look like mag chrome bricks to me.

https://www.youtube.com/watch?v=fu4lAGp2PHc

Yes, I used them for the cooking floor.
Not sure what mag chrome bricks are...is that a good thing if they are?

[wotavidone]

Have you used any of those black bricks? They look like mag chrome bricks to me.

https://www.youtube.com/watch?v=fu4lAGp2PHc

[Petter]

I think you are fine. The difference you observe may come from the production method (aggregate size, additives, sintring temperature) rather than from the actual material since the densities were similar.

Any pictures?

[wthwaites]

Petter
Alright, so I am halfway into the dome construction (basically right above my arch door height - course 5) and actually ran out of the bricks I decided on using (the orange "L" looking on in the picture in post #11. These bricks were very hard to cut with a diamond blade on my miter saw.
I then decided to use the use the other orange brick (square in post #11) and cut to the dimensions I needed for my remaining courses. I was surprised to find that these bricks were WAY easier to cut in comparison to the initial bricks despite being the densest brick out of the bunch. Is this something I should be concerned/worried about, or am I overanalyzing things?

[wthwaites]

No, I'm using the other orange bricks in my pictures for the dome. Those are 9" x 4" x 3" so similar to you, not as much thermal mass as others, but I may cast an additional layer of thermal mass; I haven't decided. Its heavy duty bricks so I may not need to since I've already doubled up my insulation as it will be 4" thick.

[Neil.B]

You would of used more blades and time and anxiety cutting off the taper then cutting to size

I'm in the UK and use kiln dried sand for slurry and laying. It's usually used for filling the gaps in block paving.
Someone else with experience will be able to confirm the use of silica.

Are you using the same bricks for the dome? My bricks are 12"*6"*3" and cost about £1.70 each, so I cut them in to 6 to give me bricks of 4"*3"*3". My dome is 4" thick, so not quite as much thermal mass as others who have cut bricks in half(4.5") ...but much cheaper to build.
I bought the last pallet of 177 bricks and only used half, about 10 of the ones used were wasted from experimenting.

You could cut yours simular, maybe in to 4 to give you bricks @ 100mm*100mm. 2 will be 80mm-90mm and 2 will be 90mm-100mm. To keep each course level keep all the same size tapers on the same course and all the 90mm inside. You may need to alternate the courses to keep the dome shape...Worth experimenting.

[wthwaites]

My bricks are tapered to about a 4mm difference. I made a slurry mix to level them.

For your slurry, you used a mixture of sand and fireclay? Can Silica Sand be used?

[wthwaites]

My maths is no good so feel free to correct me. If you cut them in to 3 length ways, so each brick will be 200mm x 65mm, you can then either put them through the saw to be 80mm or lay them on there sides the opposite way round, so 80mm and 100mm touch. This would give you a rectangle 180mm x 200mm x 65mm for only using 2/3 of a whole brick without any wastage.

You will get more cm2 by doing the above, two full bricks side by side would be 400mm x 200mm, the above would give you 540mm x 200mm.

Hope that makes sense

Wow! Thanks so much for that advice Neil.B. That idea makes a lot of sense.
The only cost would be time and diamond blades. I believe that this is definitely worth trying out...

[Neil.B]

My maths is no good so feel free to correct me. If you cut them in to 3 length ways, so each brick will be 200mm x 65mm, you can then either put them through the saw to be 80mm or lay them on there sides the opposite way round, so 80mm and 100mm touch. This would give you a rectangle 180mm x 200mm x 65mm for only using 2/3 of a whole brick without any wastage.

You will get more cm2 by doing the above, two full bricks side by side would be 400mm x 200mm, the above would give you 540mm x 200mm.

Hope that makes sense

[wthwaites]

To eliminate the taper? I have a miter saw with a 9 inch diamond blade. I know that setup can cut the bricks for the dome, but I'm not sure if that can cut the floor bricks and eliminate the taper?
Won't know until I try but I'm doubtful...

[Petter]

Aha, okej. Can you cut the bricks?

[wthwaites]

Are they tapered on every side?

Overall its a square brick - 200mm x 200mm dimensions. They are tapered on two out of the four sides - 100mm on one side and 80mm on the opposite side for thickness.