What's wrong with some floor insulation materials in this forum ?

[MakaDemian]

I'm gonna create a new thread with my oven construction very soon but first i wanna discuss here about some insulation materials which seems that these forum is not very "happy" with them, specially after reading this article: http://https://www.fornobravo.com/pompeii-oven/brick-primer/

First of all I would like you to know that I cannot get some materials in my country like calcium silicate boards, for instance (importers issues ), so i'm trying to find some replacements that give me the same results as this kind of materials.

I would like to discuss with you all people speacially about Insulation bricks and all their varieties. So the master question here would be what's wrong with them ?

"Bricks You Should Avoid"
"These light-weight refractory bricks are designed to stop heat, and as such have low conduction and low heating holding capacity. They are often used to insulate industrial equipment. A typical insulating firebrick weighs about 2 lbs, compared with an 8 lb standard duty firebrick."

I consider this afirmation doesn't justify their lack of functionality.


I wanna get clear that price is not a discussion for me here, that's a subjective issue so i wanna discuss instead their functionality and if it meets its objective.

I'm not an expert in this area but as you you know when we talk about insulation bricks/blocks/boards there are some kind of them that are not very popular in the pizza oven world.


- Lightweight Insulation Bricks (Mullite, Bauxite, Silica, Alumina, Soft Clay, etc)

Lightweight insulation brick is a kind of thermal insulation material, which refers to thermal insulation brick with high porosity, low bulk density and low thermal conductivity.

- CLC Blocks (Cellular Lightweight Concrete)

Cellular Light Weight Concrete (CLC) is a light weight concrete that is produced by mixing cement and flyash slurry with pre-formed foam. Thermal Insulation: CLC Blocks are excellent for both Sound insulation and Heat Insulation. Due to the presence of air pockets which are not interconnected, the water absorption of CLC blocks are relatively lower than any other materials.





I can get K26 Lightweight insulation fire bricks from ISOCEL (Brazilian company: http://www.isocel.com.br/) which support up to 1400°C / 2552°F.
I would like to know if i could replace the Perlcrete/Vermcrete or even FB boards with them. They told me that I can mortar them to the slab (hearth).


SPECS SHEET:



I have seen some people insulating the oven floor with these kind of materials, but i would like to know what you think about it or if you had some experience with them.

If you had to compare them with calcium silicate boards or Ceramic Fiber boards, are they better, the same, worst? what do you think ?

Thanx,
Demian

[david s]

The data sheets for any product should show the thermal conductivity of the material. The lower the thermal conductivity the higher the insulation value. Generally the denser (heavier) the material, the poorer the insulator. Some materials that can be used to insulate are:

Calcium Silicate board
vermiculite board
Foamglas
mill board
vermiculite( various grades)*
perlite (various grades)*
LECA (lightweight expanded clay aggregate)*
pumice (free on beaches)*
scoria*
CFB (ceramic fibre blanket)
fibreglass ceiling bats
hay or straw (close to free)*
foam*

I’m sure there would be other materials I’ve omitted

* Many insulating materials can be mixed with cement, water and/or clay to assist application, but this drastically alters conductivity and requires extended drying.

[MakaDemian]

I suppose K23 bricks are much better as thermal conductivity goes.

I'm very impressive how a perlite/concrete 4:1 mix responds to thermal conductivity, I dont know why 5:1 is the standard recomended mix, specially for flooring.

[david s]

A 5:1 is a better insulator than 4:1 and has adequate strength to support the floor and oven. Of course you can make it stronger, but the more cement you add the poorer the insulation.

These are the ones we usually refer to.

https://www.engineeringtoolbox.com/t...ity-d_429.html

and

[MakaDemian]

This guy is using insulating white bricks for floor insulation, right ?
https://community.fornobravo.com/forum/pizza-oven-design-and-installation/pompeii-oven-construction/439983-another-minneapolis-wfo/page3
So.... whats wrong with it and its thermal conductivity ?

[UtahBeehiver]

If these are true insulating bricks (the white ones), insulation bricks are decent insulation with a K value of around 0.15 vs Ca Si 0.05 but they are very soft and will not stand up to the abrasion the floor takes in day to day cooking and also do not store heat like a regular fire brick will.

[rsandler]

Nothing wrong with insulating firebricks as insulation--as Utah says, they have a K value that is decent, if not quite as good as Ca Si boards. As Utah says also you don't want to use them for the cooking floor because they will abrade, but I don't think you were suggesting using them as the cooking surface. I think the reason insulating firebricks aren't often used for pizza ovens is that they are typically even more expensive than Ca Si for lower quality insulation. Poking around online I see insulating firebricks for $5/brick, and you'd need about 10 of them to get the same area as one of the Ca Si boards I used in my ovens. Even with the ludicrous shipping I had to pay to get the Ca Si boards, I still paid a lot less than $50/board. But that's prices for me living in the U.S. If you have access to reasonably priced insulating firebricks in your location, and/or don't have access to reasonably priced Ca Si, ceramic fiber board or vermiculite/perlite, the insulating fire bricks seem like a reasonable substitute.

[MakaDemian]

If these are true insulating bricks (the white ones), insulation bricks are decent insulation with a K value of around 0.15 vs Ca Si 0.05 but they are very soft and will not stand up to the abrasion the floor takes in day to day cooking and also do not store heat like a regular fire brick will.

Utah, I never said that you can use them for oven floor. They are supposed to use them as insulation material not as firebricks for the oven floor, They are supposed to replace Ceramic Fiber boards or calsil boards, perlcrete or even foamglass, so you should put them under the firebricks/tiles floor. In other words, these insulation bricks should never been touched by pizzas .

[UtahBeehiver]

I thought you asked in your post "what's wrong with this"?? Just answered your question.

[MakaDemian]

Anyone can get this boards ?

https://www.linkedin.com/pulse/why-w...201000%C2%B0C.