#1  
Old 05-15-2006, 06:10 PM
Serf
 
Join Date: Oct 2005
Location: Ontario Canada
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Default Vermicilite /Cement ratio

I am mixing my cement with 3 to 1 cement gravel mix to Portland cement. How much Vermiculite should I add to this mix to optimize the insulating value of the Hearth?
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  #2  
Old 05-15-2006, 06:40 PM
james's Avatar
Brick Oven Merchant
 
Join Date: Mar 2005
Location: Pebble Beach, CA
Posts: 4,648
Default Insulating concrete

Ciao Fudugazi,

The insulating concrete is 5-6 parts of vermiculite to 1 part portland cement. The vermiculite is the only aggregate, so in that sense, you are not adding vermiculite to redi-mix concrete (where sand and gravel are the aggregate).

Any easy way of doing this is to mix the vermiculite and portland together (where the portland coats the vermiculite) when they are dry, then you add water until you get an oatmeal texture. I have heard that mechanical mixers can beat up the vermiculite and ruin the hole structure.

The mixture is light, and easy to work with. It's also cheap and efficient.
James
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  #3  
Old 05-16-2006, 03:48 AM
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Il Pizzaiolo
 
Join Date: Jan 2006
Location: Prince Albert, Ontario, Canada
Posts: 1,480
Default Mix

James,

Just a back up here. Six to one is the ratio I'd use, and no ready mix. A mechanical mixer will beat up the vermic way too much. Mix it dry, then add water. The resulting wet mix is light and easy to work with, the lightest in the entire project.

Jim
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Old 05-16-2006, 06:33 PM
Serf
 
Join Date: Oct 2005
Location: Ontario Canada
Posts: 20
Default vermic/cement

Thanks guys Got it The mixture gets poured this weekend on Lake of The Woods!!!! Ciao Fudugazi
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Old 06-03-2011, 11:53 AM
Serf
 
Join Date: May 2011
Location: england
Posts: 1
Default Re: Vermicilite /Cement ratio

hi guys , i'm mixing my vermiculite base this weekend, do i use "ordinary" cement for the mix or do i need to use heat proof cement ??? cheers for any feedback ...Dave..
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Old 06-04-2011, 06:26 AM
Apprentice
 
Join Date: Jan 2011
Location: Perth, Wesern Australia
Posts: 178
Default Re: Vermicilite /Cement ratio

Ordinary cement..

Big tip, soak the vermiculite first.. worked a treat when i did mine..

And i just added cement till it felt right, think it ended up around 4-1 or 5-1
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  #7  
Old 06-05-2011, 08:56 PM
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Location: Vancouver Island
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Default Re: Vermicilite /Cement ratio

As Canuck Jim says, mix it gently by hand. You don't want to break up the vermiculite particles thus increasing the density and reducing the insulating value.

I suggest a 6:1 mix under the hearth and a 12:1 mix for over the dome.

Last edited by Neil2; 06-07-2011 at 07:03 PM.
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Old 06-05-2011, 11:48 PM
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Location: Townsville, Nth Queensland,Australia
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Default Re: Vermicilite /Cement ratio

Careful you don't add too much water or it will wash the cement off the vermiculite and sit in the bottom of your barrow/container. I've found 10:3.5 by volume of vermiculite, water works well and for the really fine stuff go to 10:4
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