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dmorgs 11-10-2011 09:52 AM

Lightweight Concrete
 
I'm thinking of pouring an in place, lightweight concrete chimney (vermeculite). Also, I'm going to apply an insulating coat on my dome with lightweight. The dome is recently finished.
Any of you with experience care to illustrate the difference in the two mixes. I read the section about this on the website but I'm a little confused, hoping to get a more basic understanding.
Thanks, JJ

brickie in oz 11-10-2011 11:52 AM

Re: Lightweight Concrete
 
Quote:

Originally Posted by dmorgs (Post 123316)
I'm thinking of pouring an in place, lightweight concrete chimney (vermeculite).

I should imagine it would crumble and fall over.

david s 11-10-2011 01:07 PM

Re: Lightweight Concrete
 
Vermicrete is not particularly strong and the Portland cement breaks down at around 300C so you are most likely to have a failure.

Johnny the oven man 11-10-2011 02:21 PM

Re: Lightweight Concrete
 
Better of getting an insulating refractory castable, they do make a lightweight 1400c grade material. Not crumbly at all.

brickie in oz 11-10-2011 02:23 PM

Re: Lightweight Concrete
 
Quote:

Originally Posted by Johnny the oven man (Post 123327)
Better of getting an insulating refractory castable, they do make a lightweight 1400c grade material. Not crumbly at all.

Out of vermiculite? :confused:

david s 11-10-2011 02:30 PM

Re: Lightweight Concrete
 
Johnny,
I had difficulty finding one. What was offered to me as a lightweight castable was almost as dense as the dense castable I use. What is the density and the name of the product you're suggesting?
Al,
Vermiculite is only good for 1100 C so it must be different aggregates if it's good for 1400C

Johnny the oven man 11-10-2011 02:50 PM

Re: Lightweight Concrete
 
1400c LW is 1050kg/m3, 41% alumina,42% silica,15% cement. I will chase up the content info for you. Product is from Sila. They also make Silalite LW100, which is 1000c rated and is 800kg/m3, this would also do the trick.

dmorgs 11-10-2011 06:25 PM

Re: Lightweight Concrete
 
Okay then, clear enough I guess. What about the mix for the insulating layer?

david s 11-10-2011 09:19 PM

Re: Lightweight Concrete
 
Quote:

Originally Posted by dmorgs (Post 123335)
Okay then, clear enough I guess. What about the mix for the insulating layer?

Vermicrete would be good for the insulating layer it doesn't need to be strong and won't be subjected to high heat.


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