Major Cracks and salting?

[digitalrules]

Major cracks in refractory, some pieces falling off. Not sure if mixture was too thin or did not use correct colorant. Any suggestions for fixing? This is my first try at this. Any help would be appreciated, thanks, Mike

[lwood]

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[Grimaldi]

Did you use refractory as stucco? If it is refractory...insulate it, use wire mesh, and put a couple of coats of actual stucco on it and call it done.

[digitalrules]

Yes I did; and thank you very much...Mike

[brickie in oz]

It looks to me like the salt has made the render spall off due to the salt crystals growing.

The salt must of come from the water you used in the construction.

[digitalrules]

Thanks for the information, its our southern Ca tap water? The fire brick seem to salt up more than the mortar, they were not cheap bricks. Oven is about a year old, I did several successful pizzas, then the wife decided to diet so it has been sitting and I am just now getting back to correct it and make it look a little nicer. Thanks, Mike

[Wiley]

It looks like efflorescence or perhaps that is what some here are calling salting. Here's a link to a good site explaining it:
What Causes Efflorescence and How do You Remove it? - Concrete, Slab, Efflorescence, Cracking And Crazing, Fly Ash Concrete, Concrete Subgrade, Bleeding, Cementitious Materials And Pozzolans - Concrete Construction

You state that the bricks are worse than the mortar. Am I understanding that a brick surface by itself has this coating and if so are they spalling like this outer surface?

You also say that the WFO has not been used in a while (weeks? months?). Did you install a vapor barrier under the support slab? I have seen in Egypt where ancient monuments (which survived for millenia without damage) are spalling and being destroyed by effloresence from water and water vapor from a raised water table. The water transports minerals which are deposited on and just below the surface as the water evaporates. This has been an unintended consequence of damming the Nile River. The surface of the damaged monuments looks like your ovens surface. Most locations have some water vapor transport thru the ground. That is why one places a water vapor proof layer (sheet of plastic) under a slab or on the ground beneath a home. If you didn't use a vapor barrier this problem could (most likely will) recur if you don't use your WFO on a fairly regular basis to keep it dried out.

Sorry for your problem,
Wiley

[DimTex]

I have a friend who is a mason and he told me if the sand is not properly washed of salts it can create the issue efflorescence you describe

[brickie in oz]

Any good builders supply yard shouldnt sell sand with salt in it.

Id put money on it that the salt is from the water.
It seems way to high for the salts to have traveled up from the ground.

Although, I have been wrong in the past.

[Neil2]

I expect the efflorescence is just a relic of the construction and won't be an ongoing problem. Cover it up and carry on.