I am having a go at making a pizza oven. I know very little about DIY and as such, this project is more about the experience (not the final result!).
I purchased some fire bricks but I did not expect each brick to weigh 9 kg!!
I've laid the bricks on the floor to get an idea of dimensions of the oven and to get the shape right! I've even created an wooden arch so I can 'mount' the bricks onto the arch, cement the bricks together, remove the wooden arch and hopefully will be left with a standing arch!
My concern is, will a heat resistant mortar like this be strong enough to keep this structure this way, or are 9kg bricks not meant to be built up this way? Each brick is 5cm high, 23cm wide and 19cm deep
Best Answer
Part of the reason that an arch of this sort works is the re-distribution of force (gravity) throughout the curve. As Solar Mike suggests, you just have to get it right. This would entail ensuring to have the inner contact points of the bricks carefully aligned to each other.
The result of such an alignment is a segmented circle transferring the load from the top of the arch to the sides. It's important to secure them well (your mortar helps). My malware program blocked the web link for the mortar, but be sure to follow any curing instructions to prevent the mortar from premature failure. Such process involves slow temperature increase with holds for specific time periods until ultimate cure is reached.
Having the temporary structure you describe also permits you to pre-load the build, reducing the chance of a shift during installation causing a mis-alignment. The mortar will also provide some distribution of force, but not the majority.
If you are comfortable that the compressive strength of the bricks at the circumference of the arch is sufficient to handle the weight, you should have no problems. My experience with firebrick is that they are insanely light and equally insanely fragile. I suspect the product you found is heavier because it's quite a bit stronger than the stuff I used.