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Flabuck 11-07-2009 01:20 PM

refractory concrete
Does anyone know of an alternative mix for refractory concrete not using calcium aluminate cement?

nissanneill 11-07-2009 02:06 PM

Re: refractory concrete
The so called 'poor man's mortar' is 1 part portland, 1 part hydrated lime, 1 part fireclay and 3 parts brickie sand.
This mix is quite 'stickie' and holds the cut half bricks beautifully in place to almost vertical position so is ideal for non-form work dome building. My dome is over 2 years old and has no cracks so I recommend this to all builders. I would not use anything else.
Check out my build, there are many pics, tips and tricks that I found during my rather quick build, ie. the dome and hearth built in 2 wet days. Then came the outdoor kitchen.



Flabuck 11-07-2009 02:27 PM

Re: refractory concrete
Thanks for the info on that mix Neill,I'll try it the rest of the way.Do you think I could use a similar mix and add either crushed fire brick or river rock to make concrete?I have a guy who wants me to build him an oven and I was thinking about forming the chamber walls and pouring them. Thanks!

RTflorida 11-07-2009 03:52 PM

Re: refractory concrete
You are going to need a castable refractory cement. I am not aware of anyone using a 'home brew' to cast an oven, whether done in sections or as an entire dome.
Do s forum search of castable ovens, there are several good threads here on the forum from folks who have either cast their ovens in sections or as a whole, but again, they used a premixed castable.


dmun 11-07-2009 05:45 PM

Re: refractory concrete
Any amount of portland based concrete, other than the home-brew mortar between bricks, is a recipe for disaster. A recent thread (of many) on the topic:

Firebricks are cheap in the US. There's no reason not to use them.

nissanneill 11-08-2009 04:16 AM

Re: refractory concrete
I wouldn't use the mortar mix for a concrete nor as a refractory castable material.
I used it very successfully for the mortar joints in my Pompeii but that is all I would use it for. No need to use different and expensive refractory adhesives for thinner than 3mm joints and a different one for thicker joints as many of mine went from 1mm to 12-15mm thickness with not one crack as yet on over 2 years. You will need to buy the expensive refractory material to cast an oven dome, or buy one of James's special budget models.


Flabuck 11-08-2009 07:05 AM

Re: refractory concrete
Thanks for all the info guys it's a big help.I just have one more question.I know how tall an ovens opening should be in relation to the chamber height but what about the width?I am building a 32 by 36 oven (16 inch chamber height) with a 10 inch opening height and would like to make it about 22 inches wide.Would this lose to much heat?Again,thanks for taking the time to respond to my questions.

ThisOldGarageNJ 11-08-2009 04:59 PM

Re: refractory concrete
Hi Flabuck,
My oven is a 42 inch pompei,, My door is 22 wide... I dont think the width is of too much importance as long as you have your dome height to door height ratio correct (.63) I just wanted to make sure I could slide a big a$$ pan thru the opening...


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