#1  
Old 12-08-2007, 04:22 PM
Serf
 
Join Date: Nov 2007
Location: Perth Western Australia
Posts: 6
Default Refractory Mix Cracking

Hi Can Anyone Tell Me Why ? The Refactory Sila Mix Im Using In Perth W.A
Is Cracking, Im Weting The Bricks And The Mix Im Making maybe A Little to moist

Cheers Pat
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  #2  
Old 12-09-2007, 11:51 AM
Serf
 
Join Date: May 2007
Location: Salt Lake City
Posts: 22
Default Re: Refractory Mix Cracking

Did you use the premixed refractory mortar? Im building a small scale prototype(cant afford the real one yet, but want to practice with the materials), and here in Salt Lake the premixed product is much easier to get ahold of. It comes mixed VERY wet, and from my experience, wet cements are more likely to crack. More water in the mix means more volume, and when the mix dries(even though it is a chemical reaction, not just drying), water is forced out of the cement, and this means a loss of volume. this causes shrinking.
I think. Anyone more experienced here wana back me up?
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  #3  
Old 12-09-2007, 03:04 PM
Serf
 
Join Date: Nov 2007
Location: Perth Western Australia
Posts: 6
Unhappy Re: Refractory Mix Cracking

Cheers for your input!
I,m not using a premix with water, rather a dry - premix. But what I've since learned in the forums , The're suggesting not to use an air-dry, mortar, for exactly the reasons I'm encountering !

Cheers
Pat
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  #4  
Old 01-01-2008, 03:38 PM
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Join Date: Oct 2006
Location: Vancouver Island
Posts: 1,374
Default Re: Refractory Mix Cracking

All refractory mortars I know of will shrink somewhat. If you are spanning a joint of more than 1/4 inch or so expect cracks. If you want to span a larger joint - extend the mortar with a sharp sand (mortar sand or silica sand). For 1/2 inch span, go with a 1 to 1 ratio, 1 inch span try a 3 sand to 1 mortar mix ratio. If you have tapered joints, try having two mortars - "neat" for the tight part and "extended" for the wider part.
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  #5  
Old 01-01-2008, 09:55 PM
Serf
 
Join Date: Nov 2007
Location: Perth Western Australia
Posts: 6
Default Re: Refractory Mix Cracking

Cheers for the info Neil, ended up going with the fireclay , lime,sand and cement mix recomended by Forno Bravo, and now have completed the oven. Now been sitting for two weeks and about to start firing. Will post photo's from start to finish in the next week.

Cheers
Pat
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  #6  
Old 01-04-2008, 09:16 PM
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Join Date: Dec 2007
Location: South East Australia
Posts: 7
Default Re: Refractory Mix Cracking

Hi Mark here from NSW Australia. I hope this is a suitable place to ask this question but...
I've gotten hold of some high temperature raku clay and intend to mix it with lime and sand for a dome mortar - what do you guys reckon??
ta
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  #7  
Old 01-11-2009, 07:46 PM
Serf
 
Join Date: Jan 2009
Location: Perth, Aust.
Posts: 5
Default Re: Refractory Mix Cracking

Quote:
Originally Posted by Westozchoppers View Post
Cheers for the info Neil, ended up going with the fireclay , lime,sand and cement mix recomended by Forno Bravo, and now have completed the oven. Now been sitting for two weeks and about to start firing. Will post photo's from start to finish in the next week.
Hi Pat;

Where did you find fire clay in Perth? And did it hold up OK once fired?
I'm in the process of finding materials at the moment, so an advice for stuff in Perth greatly appreciated.
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  #8  
Old 01-12-2009, 09:35 AM
Serf
 
Join Date: Nov 2007
Location: Perth Western Australia
Posts: 6
Default Re: Refractory Mix Cracking

Hi Adrian,
There's a pottery shop in Occonor. I cant remember the name right now, should be in the yellow pages under pottery supplies. There's also a perlite manufactorer in Jandacot. Fireclay has held up well well no problems as yet!If You need further help contact me at pattydazzler@hotmail.com

Goodluck
Pat
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  #9  
Old 01-12-2009, 12:01 PM
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Il Pizzaiolo
 
Join Date: Apr 2007
Location: Adelaide, South Australia
Posts: 1,870
Thumbs up Re: Refractory Mix Cracking

Hi all,
well here we have a thread with a few newbies from this wonderful land of ours. Great to see the Australian increasing the forum numbers.
Welcome to Westozchoppers (Pat), Nokka and Adrian.
The poor mans version for the mortar works fine and I haven't had any problems with mine over the 18 month build time.
Post some pics so we can all share your joys.

Cheers.

Neill
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Old 01-12-2009, 11:38 PM
Serf
 
Join Date: Jan 2009
Location: Perth, Aust.
Posts: 5
Default Re: Refractory Mix Cracking

Thanks Pat for the pottery shop suggestions. I live North of the river, and found that Stilletano's Home Hardware in Malaga stock Fondue cement. It's $47 for a 20kg bag, but it would probably cost me that much in fuel to drive to Oconner!

They can also get rockwool insulation for about $50 / m2.

I've found the perlite place in the yellow pages and will give them a call to get a price.

Last edited by Adrian; 01-13-2009 at 02:25 AM.
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