hearth slab how long

[its all in the base]

Hi all just poured the slab that i will put my fire bricks on and i used vermiculite for the top part its been 4 hours and it has not set. how long does it take. i am feeling very sad at the moment started work early so i could get into it and well friday night is not going to well.

P.S am i going to have to dig it out any info would be great will i sleep well

[MK1]

Re: hearth slab how long

I've heard it can take a couple days to fully cure and even then the stuff is spongy like cork. What was your cement to vermiculite ratio?

Mark

[its all in the base]

Re: hearth slab how long

Thanks for that MK1 it seems to be getting better now 24 hrs later i am glad you said about the being like cork.

P.s wish i had have known that. i did not sleep last night stressing about what i did wrong. My mix was 5-1.

I wonder why the whole lot will not crack once i have finished it if its going to be like cork.

Thanks all

[MK1]

Re: hearth slab how long

Base,
Some people (experienced) use even less portland cement, so yours will bear the weight. Don't get on it too soon. I'm just now pouring the hearth slab today so I've never used it, but your question has come up many times and I've read about half of everything on this forum. Do a search.
I have investigated the design James and help has put forth. It is very well thought out, and better yet field tested. We owe them.

Mark

[Neil2]

Re: hearth slab how long

Keep it damp for at least 7 days.