High Heat Mortar Primer

[les.farrell@activ8.net.au]

Re: High Heat Mortar Primer

Hi from Oz,

We have several different sands to choose from here IE river, course and fine and also brickies loam, can someone tell me which I should use please?

[Tscarborough]

Re: High Heat Mortar Primer

Concrete and mortar are not the same. They do not share the same desired physical properties. Both contain similar ingredients, but that is the only similarity.

[jacktheknife]

Re: High Heat Mortar Primer

Gentlemen,

I never realized mortar is sticky or that it is not so course as 'concrete'
{not cement} I understand now why mortar is for bricks and concrete isn't.
I also never knew there is a refractory mortar as well as a refractory cement.



Thank y'all a lot!


J. Winters von Knife

[david s]

Re: High Heat Mortar Primer

There seems to be some confusion here.
1. Cement is the powdery stuff that sticks the other materials together.
2. Concrete is the mix of cement with water, fine and course aggregates.
3. Mortar does not contain course aggregate- fine aggregate only (usually sand)
4. Castable refractory contains, among other things, both calcium aluminate cement and aggregate which is generally too course for mortar.

[azpizzanut]

Re: High Heat Mortar Primer

Hi Jacktheknife,

Mortar is "sticky" so it holds to bricks. You also want the mortar to be "weaker" than the brick so if there is any cracking it is at the joint and not through the brick. If you want maximum effect of thermal mass then either cast a dome out of castable refractory or cut each brick so the mortar joint is very tight. Also, note that manufacturers sell mortar and castable refractory products but never recommend that they be interchanged.

Cheers,

[Tscarborough]

Re: High Heat Mortar Primer

I was a High Schooler from Houston who spent my summers on the Southwestern campus lying by the river and on the Guadeloupe in the early '70s

[jacktheknife]

Re: High Heat Mortar Primer

Tscarborough,

Thank you.
I was a music major at U.T. Austin Texas in the early 70's.

J. Winters von Knife

[Tscarborough]

Re: High Heat Mortar Primer

Castable refractory is good if you are casting a shape, but not so good for mortaring together bricks. Use refractory mortar for that, and it is cheaper than CR anyway.

[jacktheknife]

Re: High Heat Mortar Primer

Gentlemen,

I read all the former posts on this thread but never heard
'Castable Refractory Cement' mentioned.
I used it when I built my propane forge and 2,000 degrees is nothing to the stuff. 1600 degrees is normal temperature while hammering metal.
Would Castable refractory Cement be of any advantage used on an oven?
Bricks are laid not with concrete but with mortar. I don't know why but then I am just a former roofer. Wouldn't cement be better?


Thank you...


Jack the Knife

[azpizzanut]

Re: High Heat Mortar Primer

Hi All,

Look for silica sand at the following sources:

Welding supply, it's used for sand blasting operations.
Swimming pool supply store. It is used in sand type water filters
Brick yards
Masonry supply stores
Foundry supply, it's used for making sand molds.
Painter's supply, it's used to mix textured paint.
Aquarium supply.

Cheers,

[mikesuttie]

Re: High Heat Mortar Primer

Sounds awesome! Looked at your build and it has really confirmed what I've been doing wrong. Your dome bricks are all nice and tightly pack together whereas mine are miles apart with a load of mortar in them think I may have to rethink things a little. Question is do I knock it down and start over or just correct it and hope for the best!! Dilemma!

[Lars]

Re: High Heat Mortar Primer

Mike,
I would cut down the lime and use the extremely fine sand ( for smaller joints) Here in the US, it is widely available and only costs a little more than 'all purpose' sand.

I am sure the 'recipe' I used is on here somewhere. 3:2:11/2) (sand, clay, portland, lime)

Just made pizza last night... and we have been using it regularly for about a year. ( regularly = about once a week)

Lars.

[mikesuttie]

Re: High Heat Mortar Primer

I think I've worked out what may be the problem, I'm making my joinings way too large. having looked at other peoples domes I can see the bricks are far closer together and I'm evidently using far too much mortar. I'm on my 3rd course I think I'll have to live with the mistakes I already made and just correct them. Lesson learnt!

[mikesuttie]

Re: High Heat Mortar Primer

Cheeers for the reply!

At the moment i'm laying everything with no probs but a day or so after the mortar has small cracks on every join. I'll just have to fill them. I'm using 1:1:1:3 (portland cement, hydrated lime, Fire clay, standard builders sand) so maybe I'll change it to 1:1:1:4 ?

Cheers! Happy building/pizza making to all

[sutto]

Re: High Heat Mortar Primer

Mike,

Something's not right for sure, i wonder what it is?

It sounds like you've just started with you brickwork. Have you for sure got the right ingredients in the right proportions? Those engineering bricks are probably not very porous and will benefit from being soaked for while. Even more so if the weathers warmish.

David

I'm going to stick with Portland, Lime, FC, Sand. 1:1:1:4. Better the devil you know.

Sutto