Zonolite

[JACK]

Has anyone used this for their hearth and dome insulating layer. It's my understanding that it is just vermiculite that is used in lite concrete. Zonolite is just a trade name used by W.R. Grace Co. Just making sure I don't use the wrong thing.
Thanks for any info

I live in North Carolina and this is what is readily available for me in my location.

Thanks

Jack

[UtahBeehiver]

Old version of Zonolite made by W.R. Grace contained trace amounts of asbestos, this issue applied to other manufactures of vermiculite as well (do a Google Search). That said, if the vermiculite that is available in your area is free of asbestos, then it is certainly a good option of both floor 5 to 1 ration (vermiculite to concrete) and dome insulation 8-10 to 1 for dome insulation. Attached are vcrete specs for various ratios.

[Gulf]

The mine that was the source for the asbestos in vermiculite was shut down in 1990. You should be ok with the Zonolite sold today. (I'm surprised that the brand has survived) However, Zonolite is not a trade name that W. R. Grace used for raw vermicultie. It is a trade name for vermiculte that has been treated with a water repellent. I remember a few discussions about the treated vermiculte. I think that I remember that the water repellent treated vermiculte was ok for refractory. I also think that I remember Tscarborough having a lot of input to those discussions.

[UtahBeehiver]

I could of been David S when he was talking about coated perlite, It seems there was an issue with the concrete being able to stick to the perlite balls.

[JACK]

Thanks for all the info. Sure wouldn't like to have loose asbestose around my grand children.
If I decide to use perlite instead, I can get horticultural perlite easily. I have one 4 cu ft bag and it look like it would work just fine. Anyone see a problem with that?

Thanks
Jack

[UtahBeehiver]

Perlite works to same ratios. I used on my build over CaSi blanket on dome.

[JACK]

Seems to me that the Horticultural perlite would work better than construction grade as it doesn't have the silicone for water repellent that might prevent the Portland from bonding to it.
Any way, I order several bags of the horticultural grade perlite this evening, so I guess I'll be going with that.
,

[david s]

I’’ve not used the silicon coated stuff because it’s not available to me, but would certainly try it if it were. The big advantage would be the reduction in water required in the mix as well as it inhibiting its propensity to absorb water, two big advantages. If it interferes with getting a decent bond around each grain I can’t really see that being too much of a problem as the stuff is so weak anyhow. You’re just trapping bubbles of air really. Has anyone had experience with this stuff and do the manufacturers have any data on resulting concrete strength? I have successfully used foamcrete which has plenty of advantages.
This thread is old and has been buried, so I’ve unearthed it here.
https://community.fornobravo.com/for...rete#post16031

[UtahBeehiver]

Gulf must be right about Tscar, I see David was not the one commenting on not using coated perlite. So any users out there of coated perlite, it would be good to see the pros and cons posted for future builders.

[Gulf]

Russell,

It may or may not have been TScar in the conversations. I'm not really sure. Actually, I'm not sure if I remember correctly what I had for supper last night . I'm pretty sure that I remember someone on the forum using it.. However, it may have been used for loose fill.