Does fire cement conduct or insulate?

[daverook]

Hi

First time poster!

I am trying to understand if fire cement conducts heat or insulates.

I am building an outdoor tandoor with 2 clay pots, and it will have a ring of fire cement to hold the 2 clay pots together. I am intending to cook naan bread and it's likely the naan bread, when stuck to the wall of the pot will go 'over' the cement.

If the cement insulates, then this means the bread won't be cooked at the point it is in contact with the cement.

Does any one have any experience with this?

 

[Beef]

I believe fire cement simply holds up to high heat, try not to overthink this

 

[mjpmap]

I believe fire cement simply holds up to high heat, try not to overthink this

Agree with this 100%. I’m saying this partially from experience as a fire cause & origin investigator. In a raging fire inside a brick or cinder block building its common that a wall will collapse. That’s not because of damage to the brick or block. The standard mortar used to hold them together breaks down quickly from high heat and simply won’t support the weight of the wall. High heat cement or mortar is meant to eliminate that problem. Any “R” factor in the cement is so negligible that its simply not an issue to be considered. That’s probably more than you wanted to know, but hope it helps.

 

[gtopp]

It's all about density, heavy firebricks and mortar/cement are very dense and therefore absorb and hold the heat well. Lightweight firebricks are very porous and filled with air, which acts as an insulator, not allowing the bricks to absorb the heat. I believe most commonly found mortar in the big box stores are dense and will meet your needs. lightweight mortar/cement would probably have to be special ordered from a kiln or furnace supplier.

 

[airedale]

Without getting into the details of specific heat (heat holding) and thermal conductivity (transferring heat between two objects of different temperatures) I would say that your idea will probably work but the only way to be sure is to build it and see. I would be more concerned about trying to get enough heat from the fire pot to bring the cooling pot to an acceptable temperature. You will need a lot of contact area between the two; large flat areas. A thin layer of cement (rather than air) to fill the gaps and irregularities in the contact area would be A Good Thing. As long as the cement layer is thin its thermal conductivity will probably not be a major factor. The conductivity of the two thick pot walls will dominate.

The difference between theory and practice is that in theory they are the same.

 

[IamMadMan]

I believe fire cement simply holds up to high heat, try not to overthink this

^ +1

The reason regular cement doesn't hold up to heat and fire is simply because it is porous; It holds moisture and when a fire is started the moisture quickly turns to steam, causing the cement to crack open and or explode.

 

[Happy Hapgood]

First of all, Welcome to your first post. As a temp control guy (retired) it works this way:


If it's actual cement or concrete for that matter either substrate will eventually assume the temp of the surrounding area. The thickness of the substrate and temp of the cooking area will influence this.