Maximum mortar joint on inner oven surface? Pompeii Oven Construction Discuss Maximum mortar joint on inner oven surface? in the Pizza Oven Design and Installation forums; Unless you have an unlimited amount of time to spend cutting each brick I would use the do the best ...

[mluttropp]

Unless you have an unlimited amount of time to spend cutting each brick I would use the do the best you can approach. If you end up with half inch joints so be it. Remember the goal here is to cook with the oven not spend allbyou tone building it.

[dmun]

I have a little bit of an issue with this - I cut every brick to avoid any mortar joint (on the inside). Then again, reality alludes me at times.

Well, yeah, me too, on both counts.

[Tscarborough]

Good, then you are building to best practices, and if you are doing it for pay, it is not really an option. If you are doing it for yourself, it is.

[dmun]

Unless you have an unlimited amount of time to spend cutting each brick I would use the do the best you can approach.

I once proposed a "cut every other brick" plan, an image a few mesages down on this thread:

http://www.fornobravo.com/forum/f8/a...tion-5617.html (Alternating Partial-Taper brick construction?)

I don't think anyone has done it yet, but I still think it's a great idea.

[jmhepworth]

I like the look better if the inside joints are minimal. And I didn't find it all that difficult nipping the edges to come as close to that look as I could. Of course the outside joints were a different matter. I used a lot of mortar there.

Joe

[Les]

Originally Posted by mluttropp

Remember the goal here is to cook with the oven not spend allbyou tone building it.

Ouch... I was just responding to the words "not practical". I equate it to never - never say never.

David - when it comes to cutting, you are the master. Your approach to the build was awesome.

Les...

[Roadkyng]

partially agree. It is not refractory in the sense it is not fired. From what the retailer told me it takes a heat of 1800 to 2100 degrees to properly fire a fireclay mixture. It is refractory compared to a standard sand mix in that it withstands much more heat. From reading it appears the homebrew mix is used in building kilns.
My joints are as narrow in the interior as possible and do not exceed 1/4". Now the exterior is another matter!

Originally Posted by Mitchamus

Since the home-brew mortar is non-refractory, it will let heat escape at a greater rate than a true refractory mortar.

If I was running a kiln or blast furnace 24/7 I would care about the excess running costs.

[Tscarborough]

Portland cement itself is not refractory, but can handle high heat. What causes problems is the aggregate. Fine silica sand is no problem, but other manufactured sands can be. If they are composed of various types of other minerals, they will explosively de-laminate (spall) when exposed to high temperatures. The best practice is to minimize joint size on any face exposed to direct flame.

ASTM C-144 is the aggregate standard for mortar that is NOT exposed to direct flame, and it allows for the use of manufactured sand so long as it is graded properly. This is important because properly graded aggregate will prevent shrinkage cracking which is a very real problem with most refractory mortars due to the fineness and homogeneous gradation of the aggregate.