Floor buckled

[Les]

Re: Floor buckled

I disagree Les. Placing the dome on the floor has nothing to do with this, nor does mortaring it down.

Clearly, if the floor was "floating" It would be a hell of a lot easier to replace. Thats where I was going with that statement. I thought about the chamfer being the cause, but if the mortar failed at that point, where could it go? To lift the brick 3/4 of an inch, something else has to be coming into play.

Les...

[Tscarborough]

Re: Floor buckled

I got ya. Yes replacement would be easier if the floor was not under the bricks.

But the advantages of the walls on the floor still outweigh placing the floor inside, I think, although certainly not for this case.


Edit- It would appear that the mortar used experienced thermo-tumescence, which means it swelled when it was heated. Many things do this. What was your mortar, DublinTom, and do you have a spec sheet on the vermiculite used (raw vermiculite is extremely thermo-tumescent).

[dmun]

Re: Floor buckled

I'm pondering the concept of thermo-tumescence. Is this different than standard expansion of materials?

[Tscarborough]

Re: Floor buckled

Yes, because a material that experiences heat expansion will return to it's normal size when it cools down. It is also a matter of degree. Perlite, for example, when it is processed from the raw material can expand 10 to 20 times in volume.

[dublintom]

Re: Floor buckled

I took out the floor today. I think i was just unlucky with the batch of bricks that I used as they seem to have failed completely. Literally the bottom half of some of the bricks just crumbled away. Interestingly the homemade mortar skim that I used to square out the brick was perfect. I am going to buy some new bricks and lay a new floor. I was lucky with the the layout in that i did not have to remove much from under the walls.
I could probably lay down the new bricks exactly the same way if they are exactly the same size but should i leave expansion gap around the circumference, and if so how much.

[Tscarborough]

Re: Floor buckled

Jeez, they were chamfered that way? No fancy explanations needed, you shouldn't have used those bricks.

[dmun]

Re: Floor buckled

That's really weird. You would think the brick, if defective, would fail on the side exposed to the fire.

To address your question, I don't think you need to engineer in an expansion space, because the dome and the floor should expand at pretty much the same rate. Any space will just fill with wood ash anyway. I suspect it's a non-issue because you are going to have trouble packing in the bricks that tight in a confined, and non-uniform space.

Good luck.

[dublintom]

Re: Floor buckled

Jeez, they were chamfered that way? No fancy explanations needed, you shouldn't have used those bricks.

I'm not sure why the bricks being chamfered should make a difference. The chamfer was removed by means of applying the homebrew mortar which was perfectly in tact. They were laid perfectly level and tight together. The bricks had quite literally turned to dust underneath. Funny considering they were high grade bricks for building a furnace and a lot heavier than the standard firebrick. I'm just glad that the dome bricks were from a different batch.

[dublintom]

Re: Floor buckled

Ok I have replaced the floor with new bricks which are about 2mm shorter than the origional plus movement of the origional floor means that there are a few places where i have large gaps at the end of some bricks maybe 5 or 6mm. I am thinking of brushing in a dry homemade mortar mix and then spraying the joints with some water and let it dry before curing the oven again. I think this is better than letting them fill with ash.

[Lburou]

Re: Floor buckled

Ok I have replaced the floor with new bricks which are about 2mm shorter than the origional plus movement of the origional floor means that there are a few places where i have large gaps at the end of some bricks maybe 5 or 6mm. I am thinking of brushing in a dry homemade mortar mix and then spraying the joints with some water and let it dry before curing the oven again. I think this is better than letting them fill with ash.

What is the latest on your repairs?

[C5dad]

Re: Floor buckled

Wow,

Looking at the cracking on the bricks, I would think that they were not properly cured - the cracking looks as if it shrunk on the top and the bottom gave way. You see, the fires were not hot enough to properly cure the bricks so they were partially green. As the temperatures rose, the bricks dried out and shrank - which is to be somewhat expected- in the neighborhood of a few mm. As the fires progressed, the tops expanded with heat then contracted during cooling while the bottoms did not have the same luxury as they cured at a different rate.

So the question is, how are your bricks now?