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Seeking advice Limecrete, Lime putty mortar and Slipform Masonry  RSS feed

 
Simon Malik
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Please excuse me if I don't articulate this right, and please don't laugh if this sounds absurd. It's a challenge to express what I'm looking to do.

I am interested in building a house for my wife and I. She comes from a Mediterranean country that typically only builds in concrete and she has a very strong aversion to standard American construction. On my end, I'm more interested in natural building approaches and budget is a strong concern. Her country has a rich but dying out vernacular building tradition using stone, rammed earth, and fired brick with lime based mortars and stucco like rendering. However in the last 50 years this tradition has mostly died out in the cities and rebar reinforced concrete rules.

My wife is very open to our building a stone house, and if I pitch the idea well enough I can probably convince her of the benefits of rammed earth, particularly if stabilized. But in her mind cement equals solid and lasting. Her brother works for a builder and built himself a nice massive concrete home, so that's what makes sense to her. Though she grew up in a very well constructed one story colonial era small stone and mortar house, so if I can propose something similar that might fly. As they say, "Happy wife, happy life.."

So I'm looking for advice. I've read a lot on Slipform Masonry and it looks like something that non-professional builders with some help can do. Whatever I build is going to be mostly rendered over anyway. What I haven't read much of is people doing Slipform stone masonry with 'limecrete' lime putty mortar and aggregate. Basically traditional pre-Portland cement concrete with large aggregate. If possible I'd like to include chunks of urbanite as aggregate also.

My idea is a massive slip-formed foundation and shallow basement walls, and first floor. If she insists on a second floor and it makes sense then perhaps a rammed earth partial second floor, though with part of the house one floor only, with a terrace or balcony on top of a garage space. If we stick to one floor she will want a walk-able rooftop terrace. In her country people sleep on the roof in the summer, wash their clothes and hang them out on roofs, and sometimes spend a good deal of social time on roof terraces. This means a relatively flat slab like roof, or low vaulted roofs with some flat space between  the vaults.

I'm planning a minimum of 14 inches wide for the foundation and basement walls. The thought dawned on me that if I compact it with a rammed then I end up with something that's basically like a dense rammed earth but instead using lime and aggregate. The problem is I'd have to use a very dry mix. Basically put the slip form down, throw in a layer of lime mortar, include rocks, urbanite chunks as aggregate, tamp it down, and raise the form.

Does this sound like a remotely sane way of building a foundation?

I'm aware of how controversial basements can be. I would want to make one with as minimal of an impact on the land as possible, but for space and storage reasons, and also in pitching the vision to my significant other, a basement is non-negotiable.

Some degree of portland cement is going to be inevitable. She's very nervous about wooden floors and really wants cement floors and roof. I can picture a ferrous cement and metal mesh ferrocement type domes as roof covering. But the thought crossed my mind, is it possible to use limecrete and ferrocement like metal lathe or mesh, or basalt rebar bars, for flooring and roofing? like ferrocement or steel reinforced cement thin slabs but using lime instead?

I realize that lime takes a very long time to properly cure. Once cured would it have anywhere the strength for this kind of application?

Basically I want to build something that will satisfy my wife's anxieties while having the least ecological impact possible, building something that we can live the rest of our 40s, 50s, and 60s in and perhaps someday pass onto another generation. While having a breathable, healthy, energy efficient house environment. These are some of my constraints, I really welcome any thoughts and advice.

Cob isn't an option for psychological reasons but my wife could be open to rammed earth. The best way I can think of doing a rammed earth home and having a basement at the same time is constructing the walls and footers using a slip-form like method. Simply doing it all this way, if viable, is also a real option instead of rammed earth. Using slipforms is mainly to get around the expense of having large standard forms for the wall pours. The idea is building it up incrementally. And throwing a bunch of fill in as aggregate.

Alternatively if building isn't an option I am thinking of finding an existing older house, say an old frame house, and using it as an existing form to build slipform masonry walls with insulation behind, against the wood walls and frames used as a virtual frame. After reinforcing foundations to support the added weight of the masonry, and gradually build out into something more sustainable and lasting than sticks. 

I hope that doesn't sound too crazy. I'm certain that some of this is simply not practical and so any advice, even "You are nuts, don't even consider this" is welcome.
Thanks.
 
Simon Malik
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An afterthought:

Some of what I'd like to do is inspired by some Spanish and North African Arab and Berber techniques. Ramming or tamping lime mortar and aggregate , instead of just earth. Or a lime rich earth, What in Spanish is called Tabia and in Arabic Tubbi. (Wikipedia has an article on its vernacular use by Spanish and early English colonial settlers in the American south, see https://en.wikipedia.org/wiki/Tabby_concrete )

I live in the midwest, and in exploring older buildings have noticed some late 19th or early 20th century ones whose concrete foundations appeared to have been made by slipforms. Rail bridges and pilings also. The tell-tale sign is the regular appearance of a seam or joint marking the top of the form when it is moved up. With weathering the joint becomes more pronounced. This is all early portland cement based work, but I was inspired by the idea that people used slipforms for substantive structural work long before I imagined (I originally thought it was a recent technique..)

Lime production is less energy intensive than portland cement, lime mortar is potentially self healing, less rigid and brittle, and breathable. It has many advantages going for it. If I could figure out a way of doing as much as possible with lime, within a budget, and minimizing the use of portland based concrete, I'd be happy.

The other thing is code. I have no idea how cities would look at the massive use of structural lime instead of portland based concrete.

Thanks !
 
B Beeson
Posts: 5
Location: dfw, TX zone 8
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This method was also called béton, béton coignet, or béton aggloméré:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=manu;cc=manu;rgn=full%20text;idno=manu0001-5;didno=manu0001-5;view=image;seq=141;node=manu0001-5%3A10;page=root;size=200

1:3:6 proportions of...
hydraulic lime:silica sand:broken bricks

Hydraulic lime is not the same as pure Calcium Hydroxide. It has additional ingredients (pozzolans), that react to form the hardening agent.



A 2nd article, describing a process closer to slipform masonry plus ramming of a dryish hydraulic lime mortar around large stones:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=manu;cc=manu;rgn=full%20text;idno=manu0009-12;didno=manu0009-12;view=image;seq=292;node=manu0009-12%3A1;page=root;size=200



Beton bricks:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=manu;cc=manu;q1=beton;rgn=full%20text;view=image;seq=0075;idno=manu0002-3;node=manu0002-3%3A8



More:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=manu;cc=manu;q1=beton;rgn=full%20text;view=image;seq=0244;idno=manu0009-10;node=manu0009-10%3A44





 
Andrew Sul
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There is a lot of confusion in the US about working with lime. I think this partially stems from the some of the terminology in the industry. In America, when you walk into a big box builders store (Home Depot, Lowes, etc) you can buy sacks of hydrated lime. These sacks are really meant as plasticisers for portland cement mortar mixes. Masons add it to their mortar mixes because it improves the workability of the mortar creating a "fat" or "buttery" mortar. The lime itself has very little to no cementious properties. It will not act as a binder. If you don't believe me, make some test cylinders. Mix sand and lime together, wait a couple of months and you'll be able to crush your test cylinders with your hand. No strength. However, if you made those cylinders out of hydraulic lime, you would get a very different result. Hydraulic limes set similar to portland cement. So what's the difference? Primarily, it's the temperature at which the lime was burned in the kiln. The limes sold in the US are burned at high temperatures and most of the mineral compounds vitrify and become non reactive. When burned at lower temperatures (around 1700F) the end product is a reactive hydraulic lime. It's easy to make lime in your backyard, I've done it hundreds of times and there are lots of videos on the internet instructing you how to do it. It's the only way that I know of to get hydraulic lime at a reasonable cost. You could import Saint Astiers or LaFarge but they are made in Europe and their kilns are coal fired. Shipping costs are very high so it becomes very expensive, very fast. So just adding BB store lime to your slipform project won't help bind your stones together. There is a way to "cheat". You can add a pozzolan to hydrated lime and it will take a dead, non reactive lime and make it reactive. It will then act as a binder. Building with lime is much more popular in Europe so it would be worth your while to research some of the european standards for lime such as EN459. Some good info here:
http://realfinishes.blogspot.com/2012/11/plaster-coating-series-en-459-12010.html
So basically, by european standards, our limes are feebly hydraulic because they have little cementious properties. You would get a stronger wall by using a sand/clay rammed earth system. Of course, you can always use portland cement in your mortar if your heart is set on stone but lime alone won't do the trick. If your wife insists on using portland cement, at least consider lightweight foamed concrete. It's easy to make and very versatile. Again, more popular in Europe than the States. Good luck.  
 
Simon Malik
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B Beeson, that was absolutely *amazing* information. Thank you so much. This technique is pretty much very similar to some of what I am looking to do. I spent the better part of yesterday, after reading your links, digging around old sources in Google Books and elsewhere on the historical technique of béton, and locating some older books on the subject.

Additionally I've read a couple of academic papers on Moroccan Algerian and Spanish Tapia-like rammed lime mixture techniques, and on 19th century "tabby" in the American South -- all variants of the same basic techniques.

Béton seems to have used a very small amount, proportionally, of portland cement in some cases, and in other cases purely lime and sand and aggregate ingredients.

The results seem to have been lasting, beautiful, and functional.


B Beeson wrote:This method was also called béton, béton coignet, or béton aggloméré:

http://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=manu;cc=manu;rgn=full%20text;idno=manu0001-5;didno=manu0001-5;view=image;seq=141;node=manu0001-5%3A10;page=root;size=200

1:3:6 proportions of...
hydraulic lime:silica sand:broken bricks

Hydraulic lime is not the same as pure Calcium Hydroxide. It has additional ingredients (pozzolans), that react to form the hardening agent.

....
 
Simon Malik
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Hello Andrew,
I honestly did not have any idea of this. It's actually a bit depressing. Thanks for the link to European standards.
I just assumed that the hydrated lime sold here in the USA was the kind of hydrated lime you could use to make real lime putty and mortar with.

I truly prefer an actual truly reactive and cementious lime over Portland, but in terms of energy costs I have to wonder if what's involved in ordering and transporting imported truck-loads directly from Lafarge ends up having the same impact as portland cement..

Adding a pozzolan is an interesting idea, if the lime was truly reactive this would make it similar to Roman Cement right? If the lime isn't reactive then what sort of strength gains would adding pozzolan give?

I'll look-up lightweight foamed concrete. Can you recommend any DIY resources ?

Thanks so much Andrew for the really important clarification.

Andrew Sul wrote:There is a lot of confusion in the US about working with lime. I think this partially stems from the some of the terminology in the industry. In America, when you walk into a big box builders store (Home Depot, Lowes, etc) you can buy sacks of hydrated lime. These sacks are really meant as plasticisers for portland cement mortar mixes. Masons add it to their mortar mixes because it improves the workability of the mortar creating a "fat" or "buttery" mortar. The lime itself has very little to no cementious properties. It will not act as a binder...

...So basically, by european standards, our limes are feebly hydraulic because they have little cementious properties. You would get a stronger wall by using a sand/clay rammed earth system. Of course, you can always use portland cement in your mortar if your heart is set on stone but lime alone won't do the trick. If your wife insists on using portland cement, at least consider lightweight foamed concrete. It's easy to make and very versatile. Again, more popular in Europe than the States. Good luck.  
 
Andrew Sul
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Roman Cement!!! Yes! Well spotted!!! I got tired of making my own hydraulic lime. It is not difficult, just time consuming. So I decided to cheat by adding pozzolan to big box store limes and I can report that it does work. I was so impressed by the results that I opened a pozzolan mine in Colorado. It's not really a mine so much as a surface deposit. My pozzolan is a natural earth product, volcanic ash, from the San Juan volcanic field and I've made dozens of test cylinders to prove that it's reactive. Along with making Roman cement, I've also made Roman papercrete which turned out to be one of my favorite experiments. And just 3 weeks ago, I made a foam generator to see if I can make foamed Roman cement. I'm going to start selling pozzolan on ebay and I'll be offering free samples for testing to interested parties. My samples will be shipped in the small "if it fits, it ships" US post office boxes flat rate boxes. I'm able to cram just over a pound and a half of ash in that size box. It's enough to make some test cylinders and get some experience with your mix design. Vitruvius specified 1 part lime to 3 parts pozzolan (by volume) for general building and you can experiment with the amount of sand you add for strength (I like 2 parts sharp sand). I haven't launched my website yet but let me know if you want a sample. If you have a local source, you can also use fly ash from a coal power plant and it will also make our dead limes react. It's another good option if you can get past the toxicity issues. The only other drawback for me is that fly ash contains carbon and this corrupts the foam matrix if you are using it for foamed cement, whether it's ordinary foamed cement or foamed Roman cement. At least, that's what I've been reading on the web. I have no direct experience working with power plant fly ash since I have a local source of natural pozzolan.
 
Andrew Sul
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Simon Malik wrote:

I'll look-up lightweight foamed concrete. Can you recommend any DIY resources ?

  


This guy is doing some interesting work with foamed concrete:

http://www.domegaia.com/

His foam generator is a bit expensive but it does work well. I made mine for $0 out of stuff that I scrounged from my scrap pile so if you are on a tight budget, you can just cobble one together.
 
Simon Malik
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Thanks Andrew, I appreciate it.
I have quite a bit to read and absorb, between beton and foamed concrete. Absolutely fascinating !

Andrew Sul wrote:

This guy is doing some interesting work with foamed concrete:

http://www.domegaia.com/

His foam generator is a bit expensive but it does work well. I made mine for $0 out of stuff that I scrounged from my scrap pile so if you are on a tight budget, you can just cobble one together.
 
Kris Johnson
Posts: 80
Location: Pahrump NV
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I am going to politely disagree with this statement
Mix sand and lime together, wait a couple of months and you'll be able to crush your test cylinders with your hand
. I have made lime mortar from lime bought at home depot, and it is still strong.

In fact! Ryan Chivers said that he will only use type s hydrated lime when available for his tadelakt projects as it was the only way he could make any gaurantee to his clients, and he knows his limes.

I'm no materials scientist but in my experience and others' it does its job. That is not to say that adding pozzolans to it is a bad idea, just that it performs well as a binder in itself.
 
Kris Johnson
Posts: 80
Location: Pahrump NV
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Another thought on pozzolans. Supposedly food grade diamotacious (spelled it wrong) is a pozzolan.
 
Andrew Sul
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I know this is confusing so here is a nice summary of the different types of limes available to consumers:

https://www.lime.org.uk/community/types-of-lime/types-of-lime.html

A quote from the above source:

Hydrated or ‘bag’ lime
This is the lime generally available in agricultural and builders merchants. It is a non-hydraulic lime produced by slaking Quicklime with a shortfall of water which results in a powder. It is generally considered to be an inferior product to the fat lime putty described above for a number of reasons but primarily because it starts to degrade from the moment it is made and can actually fully carbonate in the bag before use. Widespread use of ‘bag’ lime has given ‘lime’ a poor name because of the instances where it simply has none of its original properties left by the time the end-user works with it, hence it fails, dusts etc. If ‘bag’ lime is the only option, then it should be purchased as fresh as possible and left to soak for two days in clean water. Although the resulting product is chemically the same as ‘fat’ lime putty, it is physically different, in particular it is less ‘sticky’. A cement mix with a shovel of hydrated/bag lime in it is not a lime mortar, in this instance, the lime is simply being used as a plasticiser. It should not be used in pre-1919 buildings!

I would never use bagged lime for tataki. Ryan Chivers is playing russian roulette. Maybe his lime will recarbonate, maybe it won't. The last time I visited my parents, I found some lime test cylinders stored away in the basement. I made them when I was a civil engineering student in the 1980s and sure enough, they had recarbonated and seemed reasonably strong. If you review Simon's particular application, he wants to use lime mortar in a rammed earth wall and/or perhaps urbancrete using a typical type S bagged masons lime. In order for any non-hydraulic lime mortar to recarbonate, it must be exposed to atmosphere so it has access to CO2. Masons who have worked on buildings 100s of years old have reported that although the mortar on the surface (exposed) part of the wall had hardened, the mortar on the interior of the wall had not. That's because the interior part of the wall did not have a source of CO2 to recarbonate. So Simon's choices are to add Portland to his mix and make OPC mortar or add pozzolan to his lime so it becomes hydraulic. Hydraulic limes do not need exposure to the atmosphere to harden. Another option for him would be to use a Natural Hydraulic Lime. I haven't been able to find a source in the US, only europe, so that's why I had to make my own NHL. I sure wish a lime manufacturer would start offering NHL in the States. Maybe the natural building segment of the market is too small for them to bother with it but hopefully that will change with time.
 
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