Cob Mortar Recipe

Can anybody please tell me if I can use a simple cob recipe as mortar? Sand+Clay+Water?

It needs to withstand heat and im not sure if I can get lime where I live and i dont want to use Portland cement.

Best Regards,
Karl

Hi Karl,

There really isn't a simple answer for this without knowing all of variables. Yes, in general, but for thermal applications, durability and function may all be transient.

A-ha..

Well, I plan to use it for my rocket mass heater. I want it for binding the bricks that are to support the sides of the barrel that goes over the heat riser. Mind you, it will not be in direct contact with the burn tunnel nor the heat riser itself, and there will be a degree of perlite insulation between it and the bottom of the barrel i mentioned, so it doesnt have to withstand anything over 200-300F. I hope that helps to clarify the issue and I thnak you for taking the time with this..

Karl

I believe you should ask this question at:

https://permies.com/forums/f-125/rocket-stoves

or try to ask Eric Wisner:

https://permies.com/t/25950/rocket-stoves/Erica-Wisner-author-Art-Fire

Hope that helps...

it does..thank you!

sand and clay mortar will work fine. You should be able to use clay slip to paint the bricks as you are stacking your heat riser (sifted through a very fine screen such as a window screen) and mortar the outside corners with a high sand to clay ratio mortar.