#1  
Old 07-02-2009, 12:49 PM
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Default vermiculite to portland cement

Is a 4 cubic foot bag of cement to one bag of 94lb portland cement too little?
Also because the insulating floor is not structural I assume no rebar is used.
G
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Old 07-02-2009, 01:01 PM
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Default Re: vermiculite to portland cement

G,

It all depends on the ratio of vermiculite to cement you use. I used about 7:1 for my insulating layer and I used about 6 cu. ft. of insulating material to a little less than one 94 lb. bag of cement. As far as rebar is concerned, you should have that in the concrete layer beneath your insulating layer, so you don't need to add it here.
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Old 07-02-2009, 01:11 PM
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Default Re: vermiculite to portland cement

Papavino,
Thank you for the info. How many cubic ft total did you get out of 1 bag of portland cement with the 6-7 parts vermiculite added. I know the answer should be 7 but don't know if the vermicullite expands.
G
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Old 07-02-2009, 02:14 PM
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Default Re: vermiculite to portland cement

I didn't really see any expansion of the vermiculite. It just soaks up the water.
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Old 07-03-2009, 08:53 AM
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Default Re: vermiculite to portland cement

G.
I used 4:1 portland with a little bit of lime. Essentially, this means four coffee cans of vermiculite, one coffee can of portland, and about a gallon of water... and about 1/4 can of lime. I mixed about 6 batches for my underfloor layer. Later on I got more liberal with the mix and made about 5:1 (vermiculite: portland) and sometimes lime, sometimes not.

For a full hod of stuff ( in my case 10 coffee cans of vermiculite, 2 coffee cans of portland, and maybe 1/3 coffee can of lime) it took about 2 1/2 gallons of water.

No steel in this layer. If you press a bit with a steel trowel, you can get a waxy sort of surface on there ( very smooth)

Just use it in a similar ratio to these and if you run out of Portland, buy another bag --if you run out of vermiculite, buy another bag of that. (menards has it in the loose insulation section for 9.95 for 3 cubic ft.)

good luck.

lars.
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Last edited by Lars; 07-03-2009 at 08:55 AM.
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Old 07-03-2009, 02:03 PM
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Default Re: vermiculite to portland cement

Good info. We just got through pouring our hearth today.
will let it cure till Sunday and then layout for the insulation area pour. I am going to boarder the vermiculite & portland mixture with brick to keep the mixture nice and compacted if it decides to crumble a little around the edges while we are working. So far so good. The hardes part of all this up to this point was to put the 80 lb bags into our trailor. Glad there is only going to be a couple of bags portland. I'll have my nephew carry those and I will take the vermiculite.
Thanks and have a great 4th
G
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Old 07-03-2009, 02:09 PM
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Default Re: vermiculite to portland cement

G.
I poured the corners in regular concrete too, then filled the middle with vermic./port. the next day. Lining with brick is a good idea.

Lemme' see if I can find a picture here...
Attached Thumbnails
vermiculite to portland cement-hearth2.jpg   vermiculite to portland cement-hearth_3.jpg  
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Old 07-05-2009, 03:55 AM
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Default Re: vermiculite to portland cement

Lars,
Thanks for the pictures.
good to know that my brother and I are on the right track. We are going to put up the brick perimeter today and then get the vermiculite and portland and do our pour this Tues (weather permitting....CT is the wet state so far) and then the fun begins this weekend with the dome. How long did it take for your insulation hearth to cure ?
Thank you for the info,
G
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Old 07-05-2009, 03:55 AM
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Default Re: vermiculite to portland cement

Thanks for the pictures.
good to know that my brother and I are on the right track. We are going to put up the brick perimeter today and then get the vermiculite and portland and do our pour this Tues (weather permitting....CT is the wet state so far) and then the fun begins this weekend with the dome. How long did it take for your insulation hearth to cure ?
Thank you for the info,
G
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  #10  
Old 07-05-2009, 10:35 AM
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Default Re: vermiculite to portland cement

G.
I poured the rounded corners one day, the vermiculite the next day, and pretty much laid the floor the next. The light weight of a layer of bricks would not interfere with the curing of the vermiculite layer. In fact, they help keep the moisture in ( ALWAYS COVER any POUR using PORTLAND with plastic or water repellent tarp for a few days and keep it hydrated).

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