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bluespider55 03-21-2009 06:29 PM

Hair line crack
2 Attachment(s)
Hi all,

Have been following this forum for a long time, sorry i'm not much of a talker.
I think this is only my second post.
I am currently building a pompeii closley following the plans genourously supplied by Forno Bravo.

I elected to go with the third of a brick method to cut down the thermal mass. I now have the issue of minor cracking of the dome and conserned about the integrity of the structure.

My question to the wise is should i now add a half to 1 inch layer to the outside of the dome to improve the strenghth of it.

If so could i just use a 3 to 1 sand cement mix or would it be better to bite the bullet a pay a hundred dollars for 2 25kg bags of refractory cement.

any advise will be appreciated.



Les 03-21-2009 06:41 PM

Re: Hair line crack

The crack you have is no worse than any of ours (a lot better then some). If you cover it with a blanket, you are good.


BTW - you are up to 5 posts ;)

bluespider55 03-21-2009 06:46 PM

Re: Hair line crack
Wow quick reply.
Thanks Les,

I probably should have said that this has had no firing yet.
I suppose i could do the curing fires before the insulation and see how it stands up.

Rastys 03-22-2009 03:43 AM

Re: Hair line crack
Hi bluespider55,
what was your mortar mix that you used? How wet were your bricks when you built the lower chain beneath the crack?
I would wrap the whole dome in a thick thermal blanket, put at least 3 x 1" thick vermiculite insulating layers over a chicken wire cover with a final render coat and then dry the lot as a whole.
That crack looks to me like a join where you had a break from construction, the bricks on the bottom were dry and your mortar didn't bond as well (or at all) as it should have.



Dutchoven 03-22-2009 07:40 AM

Re: Hair line crack
I would say fire it upi and see what it does...mark it with a pencil or marker so you can see if there is any shifting...just looking at the shape of your dome structurally it looks fine...I have seen many worse conditions in brick work than that...and I agree with rastys that it is probably where you stopped work one day and started the next...I have someone wanting my nephew and I to repoint about 1/3 of his house because it appears that the days bricklaying work when it was being built had the mortar freeze before it fully is just crumbling out of the joints...about 6 feet in height wrapping nearly all the way around the perimeter of the house.

berryst 03-22-2009 08:44 AM

Re: Hair line crack
Not to worry. The dome is one of the strongest architectural designs in history. I could stand on a igloo built only of snow. Very very strong shape. There isn't even evidence of spalling. This thing will out last you. Pizza time

bluespider55 03-23-2009 03:30 AM

Re: Hair line crack
Rastys you a probably right it each chain was done on a different day.
I was supprised that it cracked like this as i always wet the previous chain down before starting again and all work was always covered with hesian and kept damp.
Also it was about three weeks after completing the main dome that this crack appeared.

Dutch i think i will do as you suggest and fire it up and see what happens, i will have to wait a few days first as i have only just completed the transition to the chimney.
I casted this in situ.

berryst Pizza time, yea i can't wait.

Have been busy reading through the posts can't wait to get cooking some of the food on here looks awsum.


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