Vegas Pompeii getting off the ground

[azpizzanut]

Re: Vegas Pompeii getting off the ground

Hi John,

Lime mortar is not a refractory product.

The addition of lime to our oven mortar is only for increasing its workability. Lime can't take the repeated high heat cycles of a refractory oven without breaking down. The amount we use in the mortar is a trade-off. Our ovens don't get much over 1000 deg so it holds up for our purposes.

Look here for information on various lime/cement mortars and their properties.

http://www.lime.org/BLG/Tate_Property.pdf

Cheers,

[GianniFocaccia]

Re: Vegas Pompeii getting off the ground

Hey Bob,

Thanks for the link to the paper on Cement-lime mortar. I found it quite interesting that evidence of using lime in mortars dates back to 500 BC. Of particular note was this:

Copeland et al (1964) found that if mortar air content is increased from 5% to 20%, a 79% decline in mortar bond strength results.

As a completely self-trained (ignorant?) mason, I have found myself taking a few extra minutes to 'whip up' my homebrew mortar feeling that the extra air-entrainment made the mortar feel more fluffy, and easier to manipulate between bricks when placing. According to the above, this is not such a good idea.

John

[azpizzanut]

Re: Vegas Pompeii getting off the ground

Hi John,

I don't think you have to worry too much about whipping air into the mortar with a trowel and weakening the bond. The type of "air" they were talking about is from an entrainment additive usually mixed in at the cement plant. Portland cements with additives have specs and the bags marked with the type.

The subject of mortar and its variations used for our oven construction is something most newbie's have questions about so hopefully we've helped a little with our discussion and references.

Cheers,

[azpizzanut]

Re: Vegas Pompeii getting off the ground

Hi All,

Here's more on mortar from a fellow forum member that I've pasted here for you.

Quoting from Lars: edited a little.

"I, too, had many questions about mortar.

Originally I got a high test bucket of dark refractory mortar to try out. It didn't seem to adhere to fire bricks very well, and needed to be fired to set. Furthermore, it dissolved when wet the next day.

Then I consulted a potter, actually two of them, who had built many kilns. They BOTH recommended the fire clay, Portland sand lime mix.

Knowing the Portland is just to knit things together and keep the rain from washing away the clay until it gets fired, I decided to put together the 'mix' of different recipes I have seen. I have worked with many different mortars, and the 3:2:1 ( and 1/2) recipe is GREAT --- fine quartz sand, fire clay, Portland, and lime.

The fluffy adherent mixture is twice the fire clay to Portland ratio. The FINE sand is good to keep the small mortar joints ( as possible) and this stuff sticks nicely ( I am up to the 7th chain with no forms.

The clay really retains the moisture a long time, so this allows the P ortland to set up very nicely without getting all the moisture sucked out of the mix.

As I understand it, the mortar is really a space filler, and not necessarily an agent of adhesion. It should get hard ( the fire clay) when fired, and the Portland, ( as I have read) will begin to lose strength on the cool down phase.

I have been cutting all my bricks at an angle so every piece is a wedge. Theoretically it would stand with just spacers in the back, and hopefully the clay will harden and become at least that ( and hopefully more )"

I hope this helps to understand mortar a little better. The recommended mixes are versatile enough that you can adjust the proportions a little to suit your needs.

Cheers,

[cvcrash]

Re: Vegas Pompeii getting off the ground

thanks for the great mortar advice... i have not been able to find a high heat mortar locally and have purchased 60 grit sand, lime, portland and fireclay.

tomorrow will be a day for the soldier coarse. thinking i will go with the 3:2:1:.5 ratio...

[azpizzanut]

Re: Vegas Pompeii getting off the ground

You're welcome, CVCrash.

Check your messages.

Today was a day of rest away from oven building. Tomorrow I will finish the 7th course. I'll also modify my indispensable tool to accommodate a little narrower brick as I begin to close in the top of the dome. I've found it useful to make up several strips of lath to support the bricks from the bottom so I can move the tool to the next station. As the bricks get more vertical they are harder to keep from moving until the mortar has set. The support sticks are a practical approach and allow a little more rapid progress.

Cheers,

[cvcrash]

Re: Vegas Pompeii getting off the ground

Here are a couple pics of the work yesterday, I managed to take the day off and make some progress.

Did the 3:2:1:.5 recipe with bricks soaked overnight and the process seemed smooth. Covered it when I was done with a soaked moving blanket and plan on keeping that wet for a couple days.


Think my next move is to create the inner arch and cut those bricks. Probably make a form for it as I want it to be an arch style, 20 inch wide and 12 inch clearance at the top. Im off again on Sunday and would like to get another layer or two done.

Thoughts?

[Laurentius]

Re: Vegas Pompeii getting off the ground

I was under the impression that you shouldn't soak your brick nor should you mortar your floor for some reason?

[cvcrash]

Re: Vegas Pompeii getting off the ground

Well I was thinking soaking the bricks would help the mortar cure in the dessert as well as prolong the life of my diamond blade.

Think next time just a quick soak for the remainder.

As for the mortar on the floor, the mixture underneath is just fireclay, sand and h2o. I spread a little of the mortar with my finger accross the joints to make it smoother. Think there is only a 1/8-1/16 inch built up. Figured I could cut that out if needed and shop vac a brick up if needed provided it wasn't one the dome was resting on.

Cheers, thanks for the feedback, I would not have even fathomed the thought of doing this without this forum.

I am a chef by trade and have iced more cakes than motared bricks.

[cvcrash]

Re: Vegas Pompeii getting off the ground

inner arch complete, came to 13.5" center height under the keystone.

got a small test of whats to come as far as cutting bricks to fit

all in all think it looks pretty good


no time to start measuring for the 20" dome an get all the shims cut

[azpizzanut]

Re: Vegas Pompeii getting off the ground

Hi All,

Who needs a wooden form? Look at the geometry of the arch, perfect, and he used materials at hand to do this beautiful work. I'm impressed.

Cheers,

[Mike D]

Re: Vegas Pompeii getting off the ground

I think you do soak the bricks before mortaring, otherwise the mortar dries out way too fast. You don't want them dripping wet or glossy, but if they are bone dry the mortar doesn't have time to set before it dries out and you lose your bond (they crack and separate). But I could be wrong.

Mike

[cvcrash]

Re: Vegas Pompeii getting off the ground

does anyone have the measurement for the shims to bring a 42" diameter oven to a 20" interior height? i realize the tool will get me to a 21" height, just would like to have the shims cut and lay it out on the floor once before i get going to visualize it.

i have a half brick soldier coarse followed by a second coarse with no angle

planning on starting the arch on the third coarse

[cvcrash]

Re: Vegas Pompeii getting off the ground

this weeks progress... pretty confident on how the dome is comming along.

cutting the bricks for the dome transition to the inner arch is challenging.

[pizza_bob]

Re: Vegas Pompeii getting off the ground

cutting the bricks for the dome transition to the inner arch is challenging.

I went through this painful process of getting the dome to arch transisiton. Not sure if this will help but let me know if you have any questions...

http://www.fornobravo.com/forum/8/pi...ld-7155-8.html

~Bob