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Forgeblast 06-29-2011 10:01 AM

Insulating slab premix?
Hi all, I have some premix left over (4-5 bags) from my reinforced slab pour, before I begin on my insulating slab, I was wondering if I could use the premix and perlite/vermiculite to create the slab, or will the sand and stone take away from the insulation properties.

chidding 06-29-2011 06:40 PM

Re: Insulating slab premix?

You are correct in your assumption that is will reduce the efficiency of the insulation.

All you want in the vermiculite (5 parts) and pure cement/concrete (never knew the right term).. in 1 part.

one little tip if i may,

presoak the vermiculite in water.. this will make your life a whole lot easier.

mrchipster 06-29-2011 06:44 PM

Re: Insulating slab premix?
Pure Portland Cement is the correct term,

Concrete is the mixture of Portland Cement/sand/and rock - sometimes a little lime is added.

chidding 06-29-2011 06:53 PM

Re: Insulating slab premix?
Thanks Mrchipster for clarifying.. I always get them the wrong way around.

Forgeblast 06-29-2011 08:29 PM

Re: Insulating slab premix?
Appreciate the fast replys, Ill pick up a bag of portland.

Forgeblast 06-30-2011 01:21 PM

Re: Insulating slab premix?
I was able to mix and pour it today. I wet the perlite first, and then dumped it into my mortar tub, added the portland and mixed well, then added some more water and mixed again. I then put it into the form and check for level. It was actually real easy to do, no stress and adding the water to the perlite first helped the portland coat it better.
Thanks all for the help.

chidding 06-30-2011 06:32 PM

Re: Insulating slab premix?
Glad to hear it all worked out ok.. wetting defintately makes a world of difference.

I dry mixed it on a cement mixer.. man was that a bad idea.. All that happens is the vermiclite/perlite sucks the water from the cement and turns it rock hard..


Forgeblast 06-30-2011 07:05 PM

Re: Insulating slab premix?
Ill post some as soon as I pull the forms. I got a mouth full of dust when I was pouring out a bag, the water seemed to keep the dust down nicely.

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