Where can I buy refractory CONCRETE? Pompeii Oven Construction Discuss Where can I buy refractory CONCRETE? in the Pizza Oven Design and Installation forums; "River gravel or crushed fire bricks Sand Calcium Aluminate cement. (if available in different grades choose the better one) Lime ...

[dmun]

"River gravel or crushed fire bricks Sand
Calcium Aluminate cement. (if available in different grades choose the better one)
Lime (lime is usually cheaper, about 80% of the cement price)
Water
You can add into this mix a little standard Fireclay if you like.

Mixture: (parts ratio is 3 x 2 x 2 x 0.5, plus water)
3 shovels of the gravel or crushed firebricks
2 shovels of sand
2 shovels of the cement
half shovel of lime
This amount will require approximately 6-7 liters of water to mix the concrete"

What do you think? It seems to be the same as the Calcium Aluminate fireclay formula from FB.

There is very little depth of experience with refractory concrete on this board. In the US, firebrick is a much cheaper, and much better product. Most of the refractory concrete (castable) experience around here is Australian, as firebricks are ruinously expensive down under. Calcium aluminate products have the reputation of being difficult to work with, but again, I only know this second or third hand.

In any event, do a search for castable refractories, and remember that most of the products you read about are going to be different brand names, and have different properties, than the ones you can buy locally. And by all means keep us posted, so your experience will be available to other builders.

[jgestner]

Hi Gang
I am considering A WFO build this summer or next. I am interested in the idea of a self cast inside or outside of some readily available form or make my own form. The first resonably priced refractory cement I have seen is this "KS-4 PLUS
All prices based on 55 lb bags $38.55
A dense, strong general purpose castable refractory for use at temperatures up to 2550°F. It combines high strength with abrasion resistance. "
I saw it at Empire Refractory Specialists Shopping Cart

Would any of you have any thoughts about it or it's suitability for casting an oven?
I still plan to build the base with firebrick but if the dome works out well enough maybe the floor could be cast with this same material.

Thanks for any insights some of you might have.

John in Merrill, WI

[david s]

I would not use lime in a mix with calcium aluminate cement. Most manufacturers recommend that alkaline materials (lime) are incompatible with cal. alum. cement. It also has the characteristic of making the brew set VERY quickly, which is annoying if you"ve mixed up a fair quantity. Proprietry mixes are prbably better to use as they contain aggregates that are stable and won't give you too much problems with excessive expansion. They also contain fibres that burn out at low temps. creating mini tubes for moisture to escape from during curing fires, to prevent cracking.
Dense castable refractories are way stronger than insulating ones and should be used in areas wher you want thermal mass or strength. Stainless steel needles are the recommended reinforcing for castables.

[jgestner]

Hi David
Thanks for the quick response. I probably didn't look hard at the site I posted above, but in my quick look didn't see lime listed in this KS-4 Plus product.
Here though the same site shows a range of prices and products, some that do list 60% alumina. Empire Refractory Specialists Shopping Cart I know I read here that someone was using the MIZZOU product they list also.

John

[jbriggs]

Trust me......there ou are peo\\arfe lots of suppliers out there that your probably not aware of. It takes a lote of research and phone calls to accomplish this. Start with a web search for castable refractories with your city listed. It will likely yield suppliers within a few hundred miles, but a phone call and a few conversations and you might find that they have a small distribution warehouse in your area. Might not be the exact product that you wanted but likely a very suitable alternate ( and I DO NOT believe that one is better than the other similar to groceries....name brand v/s proprietary, smaller company).

I was able to find an ANH company
nearby that had a warehouse within 20 miles that had a castable for $25/55lb bag, meaning I can cast a 40 " dome 3" thick for about $400.

Use your resources!!

[jbriggs]

Oh damn is should proof read more often.....

[azpizzanut]

Hi All,

For those of you that want to cast oven parts of refractory concrete I suggest you do your very best to calculate how much you need before starting a project. I made a cast vent from some bags of castable refractory left over from a job. I was certain the three bags would fill the form........it didn't, not quite. Fortunately, I was able to accommodate the shortage because the chimney base still fit the top opening.

The castable refractory set-up fairly fast but stayed tacky for several hours. A hammer drill with a suitable bolt fitted to the chuck made a good vibratory tool when pressed hard on the outside of the wooden form. Don't forget to do this or you may get lots of air bubble casts.

I lined the form with 2" wide box sealing tape. The finished surface of the vent was smooth as glass. I got lucky with that. From my limited, prior, experience with castable refractory I learned that it sticks to raw wood and makes form removal difficult. It isn't like Portland concrete. Maybe you will find my experiences helpful.

Cheers,

[david s]

You must use a release agent. I use 50% motor oil and 50% kerosene. This seems to work well, you don't want too much oil residue left on the cast surface, that's why I dilute it.