Lime mortar & wood ovens?

[TrevorML]

Re: Lime mortar & wood ovens?

No apologies necessary Dave... no offense taken...

must have been one of those days... I think I was doing a bit of the same letting off steam very early on in the thread... work gets to you like that sometimes... I know it has with me lately

a real pity work has to get in the way of life so much... wood oven bread... a good glass of red... great company... really that is all there should be... at least sometimes

[Mojoe]

Re: Lime mortar & wood ovens?

The only environmental plus that I can see from Lime is that it takes CO2 out of the air (much like a plant) and it would be interesting to know just how much.

As far as lower temperatures, consider a few of a long list of possible fuel sources cement plants utilize as a result of burning at higher temperatures:

Shingles from your house.

Petcoke, a by-product of oil refining.

Tires from say those over abundant cement/concrete trucks or even your car.

CoGeneration= turning all that heat into power

Cement plants have been governed by the EPA here in the US for many years, check out the compliance dates for Lime manufacturers: Lime Manufacturing Article

As far as the health hazards, silica is the nasty little guy present in limestone which, as we know, is used to make lime and cement. Over exposure to silica over long periods of time leads to silicosis, hardening of the lungs. Basically your lungs set up much like the mortar you're using... they slowy lose their expansive capabilities.

Just wanted to throw my nickel in the pot, seemed a little unfair to portray cement in such a fashion.

[asudavew]

Re: Lime mortar & wood ovens?

a real pity work has to get in the way of life so much... wood oven bread... a good glass of red... great company... really that is all there should be... at least sometimes

You forgot bowling.

[Dutchoven]

Re: Lime mortar & wood ovens?

OK...my perspective has changed a bit since my last post. I have since taken apart 3 fireboxes in the upstairs that were laid using the same lime putty mixture as the rest of the building. Having seen it first hand I now have even more serious doubts about a pure lime/sand putty to be the mortar for a WFO. The deterioration was significant and the mortar was very soft. Some of the areas had been exposed to moisture but, for the most part, mortar condition did not change other than dampness in those areas and less dust(which I liked better). I also would have concerns about expansion rates between our more modern medium duty firebrick and the older softer red clay solids that were used at the time. I think the old brick with old mortar would be OK but, and once again it is a big one, I don't think mixing newer with older materials. Fireclay as an additive is definitely part of my opinion and I will still hold to the feeling a some portland/calalum cement, albeit only about 1/2 to one part.
Best
Dutch

[Archena]

Re: Lime mortar & wood ovens?

http://minerals.usgs.gov/minerals/pu.../limemyb01.pdf


Info for the truly geeky.

[Thom]

Re: Lime mortar & wood ovens?

Sorry to resurrect an old thread.

Like Trevor I happen to be a "Lime Nerd". I found this forum via a Google search using "lime mortar pizza oven". I too am interested in the possibility of using lime mortar as a refractory mortar for pizza ovens.

I have a book commonly known as the "Plasterers Bible" published in 1897 by William Millar entitled "Plastering Plain and Decorative". In the back it has several different plastering recepies. Under a recepie entitled "Fireproof Mortar" he says the following:

"Two parts of the best lime, and one part each of blacksmiths' ashes and brickdust, gauged with water or stale beer, as required. This makes a good mortar for plastering round coppers or fireplaces. It becomes as hard as iron."

I imagine the blacksmiths ashes could be what we today refer to as Fly Ash. Both it and brick dust would serve as a pozzolan for the lime. I have performed my own tests with pozzolan and lime and have had very encouraging results. Have not had any stale beer to experiment with though.

Although this could be considered a concept it would be really neat to be able to replicate a historic WFO.

Thom

[jpmort]

Re: Lime mortar & wood ovens?

I am considering making my low dome pizza oven from clay, some red bricks, and lime mortar. I wonder if there is any feedback from those who have used this material? I understand that homemade ovens in Italy use lime mortar because it is able to be less brittle than concrete, and therfore does not crack in the same way.

I am also interested in how how a temperature the lime mortar can withstand, and if I need to mix in anything in with it to make it withstand 450C degrees?

Many thanks,

John

[adam2]

Re: Lime mortar & wood ovens?

I own a home in Hamilton Ontario built in the 1880's. The entire house is made of lime-based mortar of that era. The brickwork is all original and still in impeccable condition. it is a 2 1/2 storey home. Over the past couple years I have been using lime mortar with great success to repoint the basement.

A bit about the brickwork:
~~~~~~~~~~~~~~~
A structural engineer inspected the house and said she has seen homes that are 10 years old with brickwork in worse condition! All the bricks are perfectly level and the only damage is in an area where they failed to put up proper eavestrophes and dripping water has eroded the brick over the decades.

The basement is stone and needed repointing last year. I hired a couple of masons with experience working on old churches and cathedrals in England and they educated me in the lime mortar. I also learned how to properly mix, apply and finish mortar to joints. Needless to say, the original structure was built with lime mortar and lasted 130 years, and I was told their repointing work should last another 40-50 years. The stonework is now done and absolutely beautiful.

A bit about concrete repair:
~~~~~~~~~~~~~~~~
As mentioned before the house was built in the 1880's, and there have been many previous owners. Over the decades, it is evident parts were patched with concrete. In all of these areas, moisture has built up around the concrete but had nowhere to go since concrete is impermeable so the water has pushed the concrete out and separated from the stone. In some cases it took parts of the stone with it and produced spalding. The concrete has been chipped away in these areas and repointed with lime mortar. Another interesting thing I learned was the "healing" properties of lime mortar. When cracks develop, they end up sealing themselves from moisture pushing up against the lime joints. Any gaps get filled in with lime from the mortar due to moisture that seeps around the joints (this is a perfectly normal situation with lime mortar). Again, this type of joint has lasted thousands of years in many buildlings in europe (including all buildings of historical interest in Italy).

What brought me to this forum was my outdoor brick fireplace that was there when I purchased the home. It is obvious all the joints are made from quickcrete. The bricks are all spalding and splitting. I just recently noticed that as of this summer NONE of the bricks are adhered to the concrete joints. This isn't surprising - as I stated before - the moisture gets in between the brick and the concrete and pushes against the concrete and separates - this is the risk of using concrete with bricks exposed to any moisture).

The conclusion that I draw is that quickrete or pure concrete is an absolutely horrible thing to use for joints of bricks with any porousness. Lime mortar is an excellent medium to use for joints between stone and brick. The lime mortar is the sacrificial material - you NEVER want the brick to be the sacrificial material because then your structure will fall down. mortar can be repointed a lot easier than replacing all the bricks.

[adam2]

Re: Lime mortar & wood ovens?

Oh yeah, the whole reason I joined this forum is because I had a question about rebuilding a brick fireplace out of broken bricks. Anyone have any advice? I was going to reuse any bricks that are broken in 2 (or maybe 3) but the smaller pieces I was going to set aside.

For those interested, the whole reason the bricks were broken and in many cases completely in shards is because the previous owner used quickrete with bricks. Over the past few years the quickrete has separated from the bricks due to moisture.

I'll be using a lime mortar to ensure good adhesion and longevity for the fireplace. I am also probably going to use a pure lime/sand/water mix. The fireplace is only 4 feet tall so it does not require any of the structural advantages of using portland cement.

[Archena]

Re: Lime mortar & wood ovens?

I wouldn't. The thing is, once a brick is broken its 'innards' are exposed. Although brick is fired, the interior is usually much softer. Lacking the external shell, the interior wears much faster*.

Much older brick will be harder inside - longer hardening time (like concrete, brick continues to set up long after being fired - it's just much slower) - but no brick is ever as strong once broken. You can reuse them for a variety of things, but a fireplace undergoes some pretty extreme temperature changes which have been known to crack full brick - a broken brick is not likely to take it well.

Conversely, brick in brick ovens are often cut. But most are also firebrick which is better suited to oven conditions.


*I'm going by what I've read on the subject. It's not something I've read extensively about so don't take it as gospel. I think it's correct or I wouldn't mention it but I'm not as sure about this as I am about other topics I've read more about.

[Tscarborough]

Re: Lime mortar & wood ovens?

The reason the brick broke is because the portland cement based mortar is harder than the brick. Any stress is thus relieved through the brick instead of the mortar. You can reuse the brick, but the rule of thumb is that no piece should be less than 1/4 of a whole unit.

FYI, there are no structural advantages to using portland cement mortar. It has advantages in initial set and moisture resistance, but ultimate strength does not apply outside of highly engineered masonry structures.

[dmun]

Re: Lime mortar & wood ovens?

Here's a link to a Penna. based lime mortar manufacturer, much good info on site:

Lime Works.US

[brickie in oz]

Re: Lime mortar & wood ovens?

Where are the real life examples?
And net examples?

Here are some bad repairs using cement based mortars.

[adam2]

Re: Lime mortar & wood ovens?

I wouldn't. The thing is, once a brick is broken its 'innards' are exposed. Although brick is fired, the interior is usually much softer. Lacking the external shell, the interior wears much faster*.

Much older brick will be harder inside - longer hardening time (like concrete, brick continues to set up long after being fired - it's just much slower) - but no brick is ever as strong once broken. You can reuse them for a variety of things, but a fireplace undergoes some pretty extreme temperature changes which have been known to crack full brick - a broken brick is not likely to take it well.

Conversely, brick in brick ovens are often cut. But most are also firebrick which is better suited to oven conditions.


*I'm going by what I've read on the subject. It's not something I've read extensively about so don't take it as gospel. I think it's correct or I wouldn't mention it but I'm not as sure about this as I am about other topics I've read more about.

Thanks for the helpful advice, but since my last post, I went ahead and made the wall out of the broken brick. It looks rustic, but fine for outdoors.

I forgot to mention there already is firebrick lining the interior, this brick is outside of it, I guess mostly for structural support and looks.It is just a firepit for casual after dinner fires. I use it maybe twice a summer.

[KraemerBAC]

Re: Lime mortar & wood ovens?

Very interesting thread and quite a bit of "food for thought"

Thank you everyone

Peter