Crack Control and fiber addmixtures

[phipham]

Re: Crack Control and fiber addmixtures

Minimizing cracking is more important for me than thermal mass, so I am happy to add an extra layer of reinforced mortar if this leads to less cracking.

The reason why I put in chicken mesh is because this is available in the Netherlands (tiny spot on the worldmap). So I have to figure out where I can get stainless needles overhere ..

Phi

[dmun]

Re: Crack Control and fiber addmixtures

Stainless steel needles are reinforcement for castable refractory, I haven't heard of them being used in oven coating. I think they might be a little ungainly in a troweled layer.

You can get stainless steel mesh if you're concerned about corrosion, but i'm sure it's not cheap.

[wlively]

Re: Crack Control and fiber addmixtures

I don't know how effective the needles would be in cladding. I used them there because I had some left over and thought it wouldn't be a bad idea. There weren't too hard to work with or obvious in finish, but you do need to be careful as they are sharp. Can't say if it would be worth it if they were very expensive or allot of trouble to get. Casting is a different story.

I think it is best to resign yourself to having small cracks, and then plan to minimize their effect with barrier layers.

[david s]

Re: Crack Control and fiber addmixtures

Mixing some stainless needles in with your cladding mix is much faster than embedding bits of mesh in the cladding layer and has the added benefit of not having a corrosion problem.

[Fairview WFO]

Re: Crack Control and fiber addmixtures

I ended up using glass fiber reinforcing in this top coat. High melting point, Alkali resistant and easy workability in a thin coat. Glass fibers have been used for years in concrete applications. I got mine for about $5/pound at NYCON.com A pound is typically enough to reinforce a cubic yard of concrete. Not sure if that helps you overseas though.

[microbe]

This is an old thread but the info is still relevant.

I have just found this: which seems like it might be a new reinforcing additive. The good news is that is on the Gold Coast...where it is so hard to find WFO materials. But they only sell 5kg bags for $99.

This mob sells by the kg -from Tasmania

The other good news is that I am really happy with this...

First pizza, Christmas Day 2021

Thanks to all the people who have posted stuff in this forum (especially you, david s ), couldn't have done it without the info.

[david s]

Since the product has been removed I can’t tell what you’ve used. I’ve been using AR glass fibre reinforcing in the cladding layer on my ovens for years. Having deconstructed one and found that layer in very good condition I’m sticking with it.
I also now use carbon nano tube reinforcing (reinforcing on a nano scale) with both standard concretes, homebrew and castable refractory with good results.

[UtahBeehiver]

You can post info on basalt fibers such as a screen shot or txt file, we want to avoid direct commercial links due to spam, phishing or site promotion issues.

[TM66]

Hi all,

I'm about to start on a Perlcrete dome home project myself and was browsing the internet for options for dome reinforcing.
To be honest, I don't much like the look of positioning and setting the chicken wire method in a just laid dome, seems a bit haphazard.

Fibres added to the dome looks like agreat option, and when I saw the Tasmanian reference I was very interested.

Cheers.

[david s]

Do some more research. A perlcrete dome lacks the required strength, thermal mass and conductivity. However, it is a good insulator if used over brick or dense castable

[UtahBeehiver]

Plus one with David's response. There are a lot of YouTube vids out there touting perlcrete dome ovens. They are not in your best interest for a long lasting and effective oven.

[microbe]

So, during firing #2 a crack opened up in my 10:1 perlcrete insulating layer (75mm) over the house-brick dome, yet to be rendered. It closed up again when the oven cooled so I am not particularly worried about it,

I had an idea and would appreciate feedback.

I plan to fire 3 more times before rendering (looking forward to guests tonight) to give everything a chance to really dry out.

Would it work to cover the dome in glass fibre insulation, then chicken wire and render onto that.

My thinking is that the glass fibre will create a bit of expansion space, saving the final rendering shell from cracking.

Thoughts?

Thanks in advance

[microbe]

Chopped basalt is available from Southern Basalt Supply in Tasmania. $12.40/kg plus postage which was more than the cost of 2kg of fibres.

RF Composites in Geebung (Brisbane) have 3mm AR (alkaline resistant - for concrete) chopped fibre for $8.75kg + GST, but it is only sold as an 18 kg bag which is way too much.

Sorry, it seems posting a URL isn't permitted, it kind of spoils the power of sharing info, I reckon.

If anyone can find someone who will sell small bags of AR fibre, post the info here.

[david s]

Chopped basalt is available from Southern Basalt Supply in Tasmania. $12.40/kg plus postage which was more than the cost of 2kg of fibres.

RF Composites in Geebung (Brisbane) have 3mm AR (alkaline resistant - for concrete) chopped fibre for $8.75kg + GST, but it is only sold as an 18 kg bag which is way too much.

Sorry, it seems posting a URL isn't permitted, it kind of spoils the power of sharing info, I reckon.

If anyone can find someone who will sell small bags of AR fibre, post the info here.

I get my AR fibreglass fibres from a different supplier in Sydney, min supply of 20 kg. Yes they are expensive, but yours is a better price than I pay and I also have to add $100 for freight. Because they reduce so much labour I'm still well in front as opposed to using chicken wire. In addition to the AR fibres I also add the really fine propylene fibres whic reduce slump cracking, but not flexural strength. The AR fibres are widely used by the concrete countertop manufacturers, although that game is not as popular in Australia as in the US. If you can source one they may be able to sell you a smaller quantity.

[UtahBeehiver]

Yes it is unfortunate that we have to restrict links to third party sites but the Forum has been hacked several times where members have lost several weeks worth of post and info.