Cast refractory vs firebrick construction

[Onojoe]

Hey all,

Doing research as the first step in building my pizza oven. I would love to hear any thoughts or opinions on cast refractory construction vs fire brick construction. Is one better performance wise? It seems to me that a cast oven would be an easier and quicker process. If one is better, how much better,

Thanks,
Joe

[david s]

Hi Joe,

The density and thermal conductivity of dense castable refractory is much the same as dense firebrick and the performance also much the same. Most cast refractory ovens have walls around 2””, thick while brick ovens are usually double that because there is insufficient strength in mortar joins only 2” thick. Any large pieces of cast refractory are subject to cracking due to the uneven heat applied and therefore uneven thermal expansion. Castable refractory relies on a chemical bond of the materials unless it is fired to around 1000 C at which stage the material is essentially the same as a fire brick, but which is neither possible or desirable in a WFO as the temperature rise must be slow and controlled. This is only possible if the castings are fired in a kiln, something no oven manufacturers do, to my knowledge. The chemical bond however is sufficient for the castable to be serviceable for many years (probably generations) in the temperature range in which we operate. The speed of construction is the casting methods big advantage. The build can be done in weeks rather than months compared to a brick oven. Here is a good and well documented build to start with.
Cheers,
Dave
https://community.fornobravo.com/for...and#post396954

[Onojoe]

Hi Joe,

The density and thermal conductivity of dense castable refractory is much the same as dense firebrick and the performance also much the same. Most cast refractory ovens have walls around 2””, thick while brick ovens are usually double that because there is insufficient strength in mortar joins only 2” thick. Any large pieces of cast refractory are subject to cracking due to the uneven heat applied and therefore uneven thermal expansion. Castable refractory relies on a chemical bond of the materials unless it is fired to around 1000 C at which stage the material is essentially the same as a fire brick, but which is neither possible or desirable in a WFO as the temperature rise must be slow and controlled. This is only possible if the castings are fired in a kiln, something no oven manufacturers do, to my knowledge. The chemical bond however is sufficient for the castable to be serviceable for many years (probably generations) in the temperature range in which we operate. The speed of construction is the casting methods big advantage. The build can be done in weeks rather than months compared to a brick oven. Here is a good and well documented build to start with.
Cheers,
Dave
https://community.fornobravo.com/for...and#post396954

Thanks David, very informative. The speed of the build is what appealed to me. I just wanted to make sure I was not sacrificing performance.