Crushing Firebrick

[adampottebaum]

I'm planning a 30" (2-3 inch walls) homebrew oven with a firebrick hearth.

Quick questions on crushing the leftover cuts from rounding off the oven floor:
1. Can I just crush up the extra firebrick bits and put in my homebrew mix?
2. What's the best way to go about crushing them up? There won't be many, probably 2 or 3 bricks worth, 8 lbs. each (not insulating bricks).
3. Do I leave everything else in the same ratios?
-I'm planning the standard 3:1:1:1 mix, I saw one of David S's posts recommending removing as much sand as crushed firebrick used.
-Also, in that same post by David S, I saw he recommended not using the dust from crushing, is there a reason why?

I've calculated out about 12-18 gallons of homebrew for 2-3 inch walls, 2-3 gallons per "part" of the mix, so 2 or 3 firebricks worth isn't a large amount to add, I just hate throwing away perfectly good cuttings.

Thanks for any help.

Adam

[Toomulla]

using dust will make the brew very sticky and hard to work I personally don't see any value in the idea.

[deejayoh]

Actually - you can use the dust in place of fireclay in your home brew. It is basically the same thing. If you are cutting your bricks using a brick saw, you will have so much of the stuff that you really don't need to buy any fire clay.

[UtahBeehiver]

I suggest you PM or reach out to David S directly regarding using firebrick dust/slurry/aggregate in "casting" with home brew. He is our casting guru.

[david s]

I'm planning a 30" (2-3 inch walls) homebrew oven with a firebrick hearth.

Quick questions on crushing the leftover cuts from rounding off the oven floor:
1. Can I just crush up the extra firebrick bits and put in my homebrew mix?
2. What's the best way to go about crushing them up? There won't be many, probably 2 or 3 bricks worth, 8 lbs. each (not insulating bricks).
3. Do I leave everything else in the same ratios?
-I'm planning the standard 3:1:1:1 mix, I saw one of David S's posts recommending removing as much sand as crushed firebrick used.
-Also, in that same post by David S, I saw he recommended not using the dust from crushing, is there a reason why?

I've calculated out about 12-18 gallons of homebrew for 2-3 inch walls, 2-3 gallons per "part" of the mix, so 2 or 3 firebricks worth isn't a large amount to add, I just hate throwing away perfectly good cuttings.

Thanks for any help.

Adam

Crushed firebrick makes an excellent aggregate for a castable refractory. I've done a fair bit of it and it's hard work. Insulating firebricks are much easier, dense firebrick much more effort, but for an oven you want a dense, strong inner dome so use dense firebricks not insulating ones. The reason the fine dust is discarded is because it interferes with the cement proportion ie too much really fine material will require extra cement to bind it up and it increases shrinkage, particularly if you're already using clay in the recipe. For a castable crush up the brick to nothing greater than 1/4". The fine material does make the mix sticky and this is a quality you want in your mix so it will hold together nicely, you just don't want too much of it though .I make a fence from bricks on edge to prevent the material spreading too far, then place the firebrick inside it and start breaking it up with a hammer. Wear a mask, breathing in brick dust is quite dangerous. A respirator mask is much better than a next to useless paper dust mask.

"The aggregate should be made up of particles of various sizes, from about 1/4" in diameter to grains as small as sand or smaller. The proportion of very fine particles should not be too great, however." Daniel Rhodes, Kilns.

[adampottebaum]

Thanks for the response everyone. I ended up with about 3/4 of a 5 gallon bucket worth of bricks. I bought 40 bricks, I think I have 2 or 3 complete bricks left and a bunch of 1/2 or smaller cuts.

I do have a respirator, so I'll be sure to use that.

These are dense firebricks, they weigh about 8 lbs. each. I will sift out the small pieces from the dust and use small pieces only.

Deejayoh, I wish I would have asked this before buying everything, I could have saved $60 on ordering fireclay... If I use too much of the fireclay on my sand/fireclay bed to level out the floor I will save some of the dust to use.

I ended up picking up a 12" diamond coated saw blade for my miter saw. I soaked the bricks in a bucket of water for 5-10 minutes each and they cut very easily. I picked up the saw for $60 at Menards, I'm sure I will use it again on another project. The bricks are still dirty from cutting and from being stacked up out of the way while I sanded/smoothed my counter off. They will get cleaned when I move them to put down the sand/fireclay leveling bed.

But just to confirm, I don't need to adjust my recipe adding small pieces/aggregate of firebricks, correct?