Budget Build 36"

[Laspaz]

Re: Budget Build 36"

Thanks for the replies.

I ended up going 7/8:1 ratio. This should be ok (in my mind) as the pumice is a solid animal with no squish or cork type compression that the vermiculite/perlite has.

Also, much less water was required as the pumice is a damp product. Depending on the (varied) moistness of the bag of pumice, I added just enough water to make a light concrete consistency with do slurry left in the bottom of the wheelbarrow. Some batches needed about 200ml, others needed about 1000ml. It will be interesting to see how the product dries now.

I ended up using 6x 20kg bags.

On a side note, I am sure mixing the concrete and insulation material would have been a more pleasant experience if my wheelbarrow tyre wasn't flat...

Questions:

I have left a 20cm (6") area at the front of the landing with no insulation as I would like to use concrete here. Is the heat low enough on the outer landing to use concrete? (I will have 4" of brick on top of the concrete also)

How much fire clay did you guys use for your build? I will be using the homebrew mix and my bricks will be cut with a bolster so my joints will be larger than most. The problem for me is 20lb of fire clay here in NZ is $55 + freight. Also, I need the powder form, not the wet form right?

Thanks,

Bevan

[david s]

Re: Budget Build 36"

If you cover your supporting slab with vermicrete then it will act to keep the supporting slab damp and cure it well for you. The bigger problem is the elimination of water from the vermicrete. As it takes about double the amount of water that standard concrete takes, it will take much longer to dry. I like to leave the vermicrete slab as long as possible to dry (weather permitting) because it is way more difficult to remove the water once you've built over it. My test explains my reasoning.

[brickie in oz]

Re: Budget Build 36"

I wouldnt worry about the 1 week of curing for an oven slab, thats just for high end high tensile work which an oven isnt......

[cobblerdave]

Re: Budget Build 36"

Thanks team, I will up the recipe to 5:1.

Dave, are you saying to hold off on the insulating layer for a week?

I have the form done this afternoon and was going to do the insulation layer tomorrow and let it cure for a week with the concrete. Is that a good plan or do I need to leave the slab alone for a week before insulating?

[ATTACH]38921[/ATTACH]

Thanks,

Bevan

Sorry Bevan went to default settings there, I would always leave concrete a week to cure before doing anything..,but. Thinking about it you got the form in place and its not a heavy layer, why not!!!
Regards dave

[Laspaz]

Re: Budget Build 36"

Thanks team, I will up the recipe to 5:1.

Dave, are you saying to hold off on the insulating layer for a week?

I have the form done this afternoon and was going to do the insulation layer tomorrow and let it cure for a week with the concrete. Is that a good plan or do I need to leave the slab alone for a week before insulating?



Thanks,

Bevan

[cobblerdave]

Re: Budget Build 36"

Thanks Al, I guess I will go for the big reveal then

I mixed up a 10 to 1 pumice/cement mix this morning to see if that will be enough to hold together for the floor insulation. I was able to pop it out of the cup I used for a mold after about 20mins.

It is not baking in the sun and after a day or so I will put a brick on top and see if it holds.

Photos for those interested:

Gudday
Looks for all the world like a chocolate crackle only grey
I would also up the chocalate to rice bubble ratio to 1:5 and be patient and let it set. A row of bricks on the slab will give you a containment edge but again let the concrete slab time to cure give it a week.
Regards dave

[david s]

Re: Budget Build 36"

With vermicrete the usual mix is 5:1 to make it strong enough. I would assume that you would need the same ratio with pumice. 10:1 vermicrete is fine for insulation over the dome but not enough strength for under the supporting slab IMO, unless you have structural concrete containing the sides.

[Laspaz]

Re: Budget Build 36"

Ha! I guess that would work... everyone says the air is doing the insulation. I wonder what sort of strength would remain after the peanuts melt.

I though the pumice was a lot like a rice crispy treat (rice bubble bar)...

Bevan

[brickie in oz]

Re: Budget Build 36"

Cool, I will get on to the insulation form work. Hopefully that ratio should be good enough.

Thanks

Bevan

Your thread got me thinking, have a read.
http://www.fornobravo.com/forum/f44/...tml#post161847

[Laspaz]

Re: Budget Build 36"

Cool, I will get on to the insulation form work. Hopefully that ratio should be good enough.

Thanks

Bevan

[brickie in oz]

Re: Budget Build 36"

It only failed because it wasnt contained, if it is contained in a structure then it wont fail.

[Laspaz]

Re: Budget Build 36"

Ok, results are in. I tested the insulation compression with bricks.

This test was done 90 minutes after mixing.

The puck of insulation was about 3" wide by 2" high.

The puck held 3 full bricks for about 2 minutes before it collapsed. the last brick was too much I guess.




SO based of the very short time period I allowed, do you think the 10/1 ratio is sufficient?

Thanks,

Bevan

[Laspaz]

Re: Budget Build 36"

Thanks Al, I guess I will go for the big reveal then

I mixed up a 10 to 1 pumice/cement mix this morning to see if that will be enough to hold together for the floor insulation. I was able to pop it out of the cup I used for a mold after about 20mins.

It is not baking in the sun and after a day or so I will put a brick on top and see if it holds.

Photos for those interested:

[brickie in oz]

Re: Budget Build 36"

The revel is nothing more than a stop for the door to sit against, you can make it as big or small as you like, or leave it off.

[Laspaz]

Re: Budget Build 36"

Sorry shortnstout, I don't know anything about refractory cements. Sounds like it should work fine though? Good luck!

Can anyone educate me about inner to outer arch reveals? I would like to make it large (like 4" perhaps) Is there any issue with doing this? I assume it may make the chimney a little more complicated but are there any other reasons to keep it only at 1-2"?

Here is the look I am digging:


Cheers,

Bevan