Lime mortar & wood ovens?

[TrevorML]

Re: Lime mortar & wood ovens?

Hi Dutch (and James, Les and others)

if your wall already uses lime mortar I personally would stick to pure lime mortar as I have seen real life examples and somewhere on the net where the use of cement in mortar has led to VERY serious degradation of the surrounding material do to the impervious nature of cement retaining all of the moisture in the brick/stone leading to the material basically just rotting away... will see if I can find a link to some on the net...

the setting time is not too much to worry about really... the original builders built the building with it and it was fine and is still standing... the long setting time refers more to the complete set when the full chemical process has taken place... I could easily walk on my paving the next day with no problem and the render could be touched... altho could scratch it for a couple of weeks but now it like stone...

infact when laying bricks... the mortar sets very firm within minutes it seems but remains damp and fragile only if knocked until the next day or so...

I was hesitant at first until I kept on reminding myself that in the order of 3 - 4000 years of continuous use is not too bad a track record in the use of lime mortar... how long has portland cement been around... 150 yrs and only about 70 to any scale... sort of speaks for itself really

same issue with mud brick and pise... the critics say it is not strong enough to stand up to the ravages of time, weather etc etc... but there are examples that are 2000 years old still standing and still in use... what is important is HOW it is used and the detailing used in it's use... not the material itself

the uptake of cement has more to do with politics and business and money rather than the inadequacies of the materials themselves... cement enabled faster construction of thinner walled building techniques which meant that the builder could be in and out of a site quicker and with less of a cost to him in materials and labour... the typical trend with all of the 20th cent processes... seems to have been the dawn of the age of the accountant, and the bottom dollar, in all decision making processes... environmental and people issues just did not register at all... obviously there were other issues at play as well... the Great Depression... the lack of materials after the 2 big wars... etc etc... but the bottom dollar approach had a very big part to play in it

this whole attitude towards cost and the lack of consideration for the environment plays throughout so many areas... paint manufacture, cabinetry etc... where big business dominates the initiation of processes that are followed... I remember reading a long time ago about a paint company employee going to one of the Shaker communities and in a "display" house sneaking a sample of the paint from the walls only to go back to the lab and reverse engineer the samples to work out the original recipes and then patent them... not for the betterment of mankind and building practices in general... but to shelf the recipe so no one could ever use it commercially... as it lasted FAR TOOOOOO LONG !!!! hence less dollars for the business community... whereas these recipes used originally were not held in monopoly but freely available for all

this is not about any luddite principles at work... just a respect for the environment and people...

there is my soapbox for the day... I can see this is going to be one of those days at work... I can just see it...

but it would be good to have some knowledge chime in on the use of pure lime mortar use in wood ovens

cheers
Trevor

[TrevorML]

Re: Lime mortar & wood ovens?

Hi Paul

I do watch Grand Designs... but unfortunately we missed last weeks episode!!! and was most peeved when we realised and did not tape it!!!... is always the way that the one you miss is the most relevant

thanks for the link to the episode... must see if Borders or ABC has the DVDs

have you built your oven yet?

cheers
Trevor

[Dutchoven]

Re: Lime mortar & wood ovens?

Trevor,
Your point is very good. In my research I ended up speaking with a representative from the International Masonry Institute(he was a specialist in repointing brickwork and restorative brickwork), he is the person who ultimately recommended the very small amount of portland cement in the mixture. Many areas on our building had been patched with a straight portland mortar and the trapping of moisture created the most problems. Even with a small amount of portland the mortar mixture we ended up using is quite soft even after now almost 5 weeks since we began the project as compared to portland cement mortars after only a few days.
Thanks for caring.
Trevor are you in the masonry trade?...or some other building trade?
Best
Dutch

[TrevorML]

Re: Lime mortar & wood ovens?

Hi Dutch

not directly in the building trade... long story short... in University student admin currently but trained as an architect and after some years doing contract and freelance work ended up via a weird route in the Uni's admin... so now my training is just put to use in home reno's and continuing my love for responsible architecture and building

cheers T

[asudavew]

Re: Lime mortar & wood ovens?

seriously..........

we live in a new time and day

give up your concrete floors, hallways, and streets, walk somewhere else


I don't think a bit of cement will ruin the world.

But if you are convinced to build with lime
then build.

I look forward to your success.

[asudavew]

Re: Lime mortar & wood ovens?

"if your wall already uses lime mortar I personally would stick to pure lime mortar as I have seen real life examples and somewhere on the net where the use of cement in mortar has led to VERY serious degradation of the surrounding material do to the impervious nature of cement retaining all of the moisture in the brick/stone leading to the material basically just rotting away... will see if I can find a link to some on the net.."


Where are the real life examples?
And net examples?

I just don't get it.......

[asudavew]

Re: Lime mortar & wood ovens?

the original builders built the building with it and it was fine and is still standing...

What building?

infact when laying bricks... the mortar sets very firm within minutes it seems but remains damp and fragile only if knocked until the next day or so...

You lay bricks before?

I was hesitant at first until I kept on reminding myself that in the order of 3 - 4000 years of continuous use is not too bad a track record in the use of lime mortar... how long has portland cement been around... 150 yrs and only about 70 to any scale... sort of speaks for itself really

Really? Romans wouldn't have used cement?

same issue with mud brick and pise... the critics say it is not strong enough to stand up to the ravages of time, weather etc etc... but there are examples that are 2000 years old still standing and still in use... what is important is HOW it is used and the detailing used in it's use... not the material itself

Such as?

cement enabled faster construction of thinner walled building techniques which meant that the builder could be in and out of a site quicker and with less of a cost to him in materials and labour

Isn't that called progress?

this whole attitude towards cost and the lack of consideration for the environment plays throughout so many areas... paint manufacture, cabinetry etc... where big business dominates the initiation of processes that are followed... I remember reading a long time ago about a paint company employee going to one of the Shaker communities and in a "display" house sneaking a sample of the paint from the walls only to go back to the lab and reverse engineer the samples to work out the original recipes and then patent them... not for the betterment of mankind and building practices in general... but to shelf the recipe so no one could ever use it commercially... as it lasted FAR TOOOOOO LONG !!!! hence less dollars for the business community... whereas these recipes used originally were not held in monopoly but freely available for all

Example again, please!

Documented please.

And why didn't you mention the CO2 clogging up the air from burning wood?
Shouldn't we use a scrubber or something?

[TrevorML]

Re: Lime mortar & wood ovens?

Seriously Dave... chill...

all I am doing with this post is for my own information... and those that are interested... in the use of pure lime mortar for building an oven... I am not attempting to be the luddite and revert all to the use of lime... modern highrise developments... skyscrapers would not be possible using lime... or at least I seriously... see can be serious too ... do not think it could be used for this type of construction...

"What [original] building?"... that is Dutch's that he was referring to in his comment... his own house which had been built using pure lime mortar...!!

the examples... if I have the time I will chase them up... from readings a long time ago so have to find where they were...

yes... I have laid bricks before...

sure the Romans would have used cement if they had it... but that is besides the point... they burnt all of the marble statues on the Colosseum in Rome to make lime... some archaeologists even say they burnt the marble facings of the pyramids to make lime and for other uses... not particularly bright from an cultural/historical perspective but they saw it as a cool thing to do... even tho now we may see it as a bit dumb...

the 2000 year old building... middle east and north africa... don't have the refs with me... sorry left those books out of my work bag... my bad

so progress if the utilisation of systems that contribute more highly to energy consumption, waste, lack of ease of re-cyclability (??) etc etc the "progress" argument really is a bit of a furphy... but that is my opinion... and out of this topics area

"Documented please."??? I did not think I was having to write a full dissertation to be able to ask a question here... thought it was just a bunch of nice folks interested in the lost arts of wood oven cooking/baking where one did not have to go around justifying ever single statement one makes as my comments were in NO way threatening to anyone at all... just observations and the like... and I did provide links at the very start of the thread... if anyone wanted to find more indepth info they were always welcome to do their own follow-up research rather than be spoon fed

CO2 for wood burning... sure... not good... but neither is all the CO2, CO, and the rest of the noxious gasses released from the over transportation of cement compared to a more local system traditionally used in lime production...

the real life examples of cement based mortar repairs to lime mortared walls being damaging... search the net until I can find the links... as I said I would when I can as I did not have them handy at the time... and ask any heritage architect in Europe, UK, Australia... and I assume the US... and they will attest to the problems associated with cement in repair work...

As for "don't think a bit of cement will ruin the world"... sure if it was only a "bit" but cement manufacture is HUGE and a huge energy consumer... at least trees are renewable and can be used to uptake the CO2 they released in burning

BUT...

this is ALL way outside the scope of my initial inquiry as to the hows and whys of lime mortar use in wood oven construction... and if anyone doesn't like the use of pure lime mortar then they do not have to concern themselves with this line of questions... it was directed at those that want to or those that have first hand experience, rather than a conversion exercise

[james]

Re: Lime mortar & wood ovens?

Hey all,

Great topic. I am learning a great deal from this thread -- and I have particularly enjoyed the lime-cycle info. As someone working on lime-based plasters for walls, this is excellent. I have read many times that you should never repair an old lime plaster with portland-based mortars. Though, of course, there is not a huge amount of lime plaster in the U.S.

Let's keep it positive -- other than the fact that concrete, along with some other things, is not very friendly to our planet. :-(

As an aside, one interesting artifact of the Italian renaissance is the large number of Roman marble statues and building that were crushed, fired and ground for the fresco's we all enjoy so much. The coliseum was used as a quarry for the Vatican, and much of the early modern (1300's onward) world used the ancient world as a cheap supply of building materials. The ancients kick-started our economic development.

As another aside, did you know that the same person who came up with lead additives in gasoline also invented PVC's in aerosol cans. Global warming and ozone depletion -- all in one lifetime. Wow.

So let's avoid that, and build some sustainable ovens. :-)
James

[TrevorML]

Re: Lime mortar & wood ovens?

As another aside, did you know that the same person who came up with lead additives in gasoline also invented PVC's in aerosol cans. Global warming and ozone depletion -- all in one lifetime. Wow.

what a legacy to leave behind... all in the name of progress...

So let's avoid that, and build some sustainable ovens. :-)
James

hear hear!!

[Mojoe]

Re: Lime mortar & wood ovens?

Now I'm really curious, why is concrete environmentally unfriendly?

[TrevorML]

Re: Lime mortar & wood ovens?

the "lime cycle" link about is pretty self explanatory as to the ecologial benefits, but here are some other links...

Lime

A conservation engineer?s view on the use of lime mortar

A brief history of lime

Lime and Cement Technology: Transition from Traditional to Standardized Treatment Methods ... a direct link to a PDF



From the Building Lime Forum

Why Use Lime?
*
1. Lime allows buildings to breathe?In the search for building materials sympathetic to traditional construction, lime was found to the one of the most important. Lime binders are promoted by the Society for the Protection of Ancient Buildings for repairs because they allow buildings to breathe.
2. Lime provides a comfortable environment?Hygroscopic materials such as lime plasters, mortars and renders stabilise the internal relative humidity by absorbing and releasing moisture. This makes for a more comfortable environment and reduces surface condensation and mould growth.
3. Free lime enables autogenous healing by precipitation?When buildings made with lime are subjected to small movements thay are more likely to develop many fine cracks than the individual large cracks which occur in stiffer cement-bound buildings. Water penetration can dissolve the 'free' lime and transport it. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous healing.
4. Free lime encourages the growth of calcite crystals?Calcite crystals tend to be larger than those formed by more complex compounds. The crystals form in voids in lime-rich environments. Crystal growth therefore adds strength over time and allows more permeability than dense mixes with little or no free lime.
5. Lime provides good adhesion?The fine particle size of lime, far smaller than cement, is linked to the root meaning of the word 'lime', which is 'sticky material'. Due to the fine particle size mixes penetrate minute voids in the background more deeply than other materials. They bind gently and the stickiness gives good adhesion to other surfaces.
6. Lime mortars can protect adjacent materials?Lime mortars with a high free lime content have the benefit of high porosity and high permeability. These characteristics allow lime mortars to protect other adjacent materials by handling moisture movements through the building fabric and protecting masonry materials from harmful salts.
7. Lime renders can assist drying out by evaporation?Dense and impermeable renders can trap moisture within the building fabric. Trapped moisture is often the catalyst for various decay mechanisms. Dense renders used in conjunction with softer materials or on weaker backgrounds can cause serious problems by trapping moisture and creating high local stresses. High calcium lime renders allow evaporation and reduce the risk of trapped moisture and decay.
8. Lime mixes have good workability?The ability of a mortar or plaster to remain smooth and mouldable, even against the suction it may experience from porous materials, is termed workability. Good workability greatly assists good workmanship, helping to achieve full joints with good bonding to the other materials. This is what makes lime-based mixes such a pleasure to use.
9. Lime binders can be durable and have stood the test of time?When used carefully, lime is exceptionally durable. Caesar's Tower at Warwick Castle has stood the test of time for over 600 years, and many cathedrals have stood longer. An outstanding example is the Pantheon Temple in Rome which has a lime concrete dome spanning over 43 meters (142 feet). This has survived for nearly 2,000 years.
10. Lime finishes are beautiful?The double refraction of calcite crystals give a unique aesthetic combining a soft texture with a lustre that has a liveliness and delight of its own.
11. Lime contributes to a healthy environment?Due to its alkalinity fresh lime is caustic and has been used, often in the form of limewash, for its disinfectant qualities. Lime is also used for water purification.
12. The use of lime has ecological benefits?Lime stone can be burnt at relatively low temperatures to achieve full calcinations. Kilns need to reach 900 to 1,000?C as opposed to 1,300 to 1,400 for OPC. Free lime absorbs carbon dioxide in the setting process of carbonation. It is possible to produce lime locally on a small scale and if this is done the consequent reduction in long distance transport also has ecological benefits.
13. Local limes enhance regional identity and diversity?The diversity of limestone types provides variety and local distinctiveness. Different limes will vary in colour, texture and setting properties. Local limes have a regional identity, they give a sense of place and provide a continuous link with the local aesthetic. Local colour is the obvious example in respect of limewashes.
14. Disfiguring by excess cement can be avoided by the use of lime?On site the temptation to use quick and easy solutions of short-term gain can lead to long-term problems. The attraction of using excess cement to be 'safe' is understandable if not desirable. The fact that it is plentiful, inexpensive and readily available adds to the problem. There is a high probability that over-strong and dense mixes that are not fit for purpose will be used in excess. The physical damage and unsightly aesthetic that results from this can be avoided by the use of lime.
This is an extract from An Introduction to Building Limes by Stafford Holmes, presented to the Foresight Lime research Conference at Manchester University on 19 November 2002.
? The Building Limes Forum. All Rights Reserved.

[TrevorML]

Re: Lime mortar & wood ovens?

concerning mud brick structures referred to earlier... some of the oldest are...

The Great Wall of China

the ancient and legendary city of Timbuktu in Mali

the medieval shire of Devon in south-western England

the 1,000 year old Pueblos of Taos, New Mexico

Bam Citadel

[barbarian]

Re: Lime mortar & wood ovens?

It's the manufacturing that produces both air and water pollutant in large quantities , the DEP allows for a large amount of pollutant in the air depending on the size of the plant but in one case that I remember locally it was 60 tons per year of air pollutant and another number for water contaminants it went straight into the hudson river in NY and any river and tributary near by is affected as well as your local water supply and wells..

remember also cement is caustic see what it does to your skin imagine what it does when it goes into your lungs..

Now I'm really curious, why is concrete environmentally unfriendly?

[asudavew]

Re: Lime mortar & wood ovens?

My apologies.

No excuses, but I had a really bad day, and I vented my frustrations in this forum.

I promise to be positive from now on.


Once again I apologize, especially to Trevor.

Dave