correct oven plans

[david s]

I'm really not sure. Because of the heat there would be accelerated corrosion and that could create more problems which could weaken the refractory way more than the strength that they would give it. I believe this is the reason that stainless steel is specified. If it were me I'd opt for no reinforcing if I couldn't get the correct stainless steel fibres. I didn't use any reinforcing in the mix for my cast mobile oven and the dome is in good condition despite plenty of abuse.

[david s]

I use Novomesh 950, for reinforced concrete, but they are two types of plastic fibres. One is really fine for compressive strength and the other are thicker and longer for tensile strength. Our local council use them for concrete paths. Way easier than steel reo.

[david s]

That would be correct, but if you order stainless steel melt extract fibres then that's what you should get.

[david s]

Yes they are designed for paths. Our council abandoned the use of steel mesh a few years ago and use these instead. They are obtained from concrete engineering supplies.
Attached are photos of steel fibres like you got and the resulting damage the rust has done where they are close to the surface.

[david s]

Oops photos didn't attach

[TapRackFire]

Based on those photos I guess I better not use these and keep looking for the stainless needles.

A supplier just called me back. He has the needles at $3.00/1pound bag. He says I will apply them at 1 bag of needles to 1 bag of the castable which weighs 45 pounds a bag.

[TapRackFire]

The castable material I picked up is called "TEX KAST HS". It is made by Refactories INC. I think I read a post of somebody using it. I tried to post a pic of it, but it is too difficult to figure out how to do it. I will try later.

[david s]

Originally Posted by TapRackFire

Based on those photos I guess I better not use these and keep looking for the stainless needles.

A supplier just called me back. He has the needles at $3.00/1pound bag. He says I will apply them at 1 bag of needles to 1 bag of the castable which weighs 45 pounds a bag.

Sounds about right.
I use 2% by weight.

[TapRackFire]

i had another question come up about my firebrick. I bought the 4.5 x 9 x 2.25 inch firebrick. I was told it was rated to 1700 degrees. I assume 1700 F.

A supplier I was trying to get my needles from said the bricks I bought are a "low or light duty". He said they would fail quickly over time. He said I should have bought the "medium duty" fire brick. He quoted these good 2700 F.

It is not too late. I can take my bricks back if I need to and get the right ones.

Has anybody used these "Low or light" duty bricks?

[TapRackFire]

I tried to mix and pour my castable this evening. I had big plans of completing
60 percent of the dome. I mixed my first bag, added my needles, and the mix looked great.

Well, I thought I had things well in hand and decided to add a second bag in the mixer and the needles. It looked good. When I turned the mixer off and started to pull the mud out of the mixer(just minutes later) the mix started to to look dry again. We added more water and it looked good again. Before I could get it out of the mixer it stated to set up. We moved pretty fast to get this chunky mess into the forms. I had to add more water and mix it even more, once it was in the forms.

I read the bag of Tex Kast and noticed you could only mix this stuff for 4 minutes and then you need to get this stuff into your forms. I will try to do better tomorrow. I hope the two bags I mixed are not lost.