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lwood 08-18-2009 05:36 AM

High Temp mortar formulation
Hi Everyone,
I am building an oven and have enjoyed reading this forum. Am stealing every idea I can. Ha ha. I can't seem to find the formulation of the high temperature mortar that was posted on this site. Can someone point me to that or just the formulation would be great.

I am in the Philippines and very few things are available, not like HD. So what I need is the sand/cement/H20 mixture for the fire brick mortar.

I don't have my pics on this station so will post later, if you promise not to laugh at the construction methods here in RP..

I have built the base, poured the slab & poured the perlite insulator. Am ready to start laying fire brick and need the the formulation. Appreciate all your help in advance and promise to post pics next time. John

Roadkyng 08-18-2009 09:41 AM

Re: High Temp mortar formulation
I am using a mix of 2 : 3 : 1 : .5
Fireclay, sand, Portland cement, Lime.

As far was water, I mix it fairly wet. It get's real 'fluffy' or 'creamy'. It's different than mixing concrete too wet as concrete will get real 'soupy'. I am in a hot, humid climate and soak my bricks prior to mortaring

dmun 08-18-2009 09:44 AM

Re: High Temp mortar formulation
from the mortar primer:

Here is the recipe for fire clay mortar, where you measure by volume (use a bucket or shovel to measure):

1 part portland
3 parts sand
1 part lime
1 part fire clay

In between Refrax and fire clay/Portland cement mortar, you can make your own aluminate mortar. It is hard to work with, as calcium aluminate can be challenging. If you get the mix, or water wrong, it won't set correctly. It partially sets very quickly, and you cannot re-hydrate it, so you have to mix it and use it in small batches. Still, if you are trying to save money and want/need the heat resilience, heat conductivity and longevity of a true aluminate mortar, it works.

1 part calcium aluminate
3 parts sand
1 part lime
1 part fire clay
The fireclay/portland homebrew is widely used, easy to apply, and is pretty successful.

The proper calcium aluminate refractory mortar has the reputation of being hard to use, sets instantly, and has to be mixed in tiny batches. It should last longer than anything with portland in it. Not many builders have gone this route, please report back if you do.

lwood 08-18-2009 08:22 PM

Re: High Temp mortar formulation
Thanks everyone!!!

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