Pumice or Charcoal Gabion System - Insulates Cob and Concrete Walls - Stucco Over Wire.

Pumice or Charcoal Gabion System - Insulates Cob and Concrete Walls - Stucco Over Wire.

This idea struck while trying to figure out how Suzanne Cornell could effectively use pumice to insulate a cob house without resorting to the use of portland cement. Here's the link to her thread ---

"Cob/pumice" https://permies.com/t/19260/cob/Cob-pumice -------------------------------------------------------------------------------------------------------------------------------------------------------------

The foundation for this idea was laid out in this thread that I produced last February. -- "Dry Stone Pebble Wall. Stone Siding for Wooden Buildings - Requires no mortar or masonry skills." You must view the link for any of the following to make sense. https://permies.com/t/12592/green-building/Dry-Stone-Pebble-Wall-Stone

This type of wall could be filled with pumice which would give an insulation R value of about 1.5 per inch according to some optimistic folks selling pumice-crete. R value drops as the proportion of portland cement rises. By using the correct gauge of mesh to contain the pumice, all cement would be eliminated. This should maximize insulation value. Rather than building concrete forms, we build the gabion wall to the existing wall. A suitable stucco wire would be included along with whatever gauge mesh contains the pumice. Cover it all with stucco and you're done. I suppose a clay based stucco could be tried as well. Tie wires would produce a very small amount of thermal bridging.

Now I have to find a source of pumice and a wall to test this on. I could see this being used as a heat shield near a wood stove as well. With a good quality water proof stucco, this might be the best idea yet for insulating a cob hot tub. But , it would then look like a stucco hot tub.

Thank you, the mad inventor : Dale Hodgins.

I'm consolidating all of my green building inventions and adaptations under one roof. The thread is called "Dale's Marvellous Inventions and Adaptations." and links to other ideas and inventions. Here's the link --- https://permies.com/t/19303/green-building/Dale-Marvellous-Inventions-Adaptations

This same gabion system could be adapted to contain softwood charcoal which is one of nature's best insulators. Charcoal is a very poor conductor of heat and it reflects radiant heat. If plenty of fine ground material were added, it should also be good at preventing convective air currents within the insulation.

Charcoal burns. Wood also burns, so nothing new there with plant derived insulation. It would all be encased under a layer of stucco, so, much like a straw bale wall, there would not be enough air for a fire to take off.

Here's the biggie. Unlike almost every other plant derived insulating material, charcoal is highly resistant to rot. Charcoal has been found in archeological excavations from Roman times even at damp sites in England and Germany. We still want to protect this insulation from water, since accumulated moisture could rot out stucco wire and adjacent wood and the R value would drop hugely for wet material. But the charcoal is not an item that is likely to break down any time soon.

Cellulose insulation which is derived from recycled newsprint is one of the best plant based insulating materials but it is highly susceptible to water damage and rot. Charcoal is less conductive to heat than is wood or paper and it reflects infrared(Heat). Expensive, high tech foam insulating boards incorporate charcoal for this reason. Therefore, charcoal could be used in situations where a high R value per inch plus radiant barrier are desired.

This will be tested along with cob/pumice, sawdust clay, wood chip clay and other insulating materials in small domes of the given material, formed over a huge metal bowl that I'm using so that results may be compared.

I began exploring the idea of charcoal insulation at the beginning of the thread entitled "Dale's Marvellous Inventions and Adaptations." Here's the link. https://permies.com/t/19303/green-building/Dale-Marvellous-Inventions-Adaptations

Check out the thread entitled "Green Building - Materials Testing and Longevity Study Facility - Facades,Roofing,Plasters, Flooring" https://permies.com/t/13262/green-building/Green-Building-Materials-Testing-Longevity – to learn of my plan to run semi scientific short term and long term performance and durability test on various green building products. Others from different regions need to join in this effort if it is to be of value to the majority of natural builders. I'm willing to provide space for those who would like to test certain systems and products on my walls, floors etc...

Dale,
Where are you located? I'd love to see your experiments.

Suzanne Cornell wrote:Dale,
Where are you located? I'd love to see your experiments.

Victoria B.C Canada on Vancouver Island. See the space below my name? We're supposed to fill that out. I'll post pictures and will issue a general invite once the quantity of constructions warrant it. Check out the Marvelous Inventions thread. I tested the charcoal in plaster thing. Seems to work !

Hello Dale,

Have you come across this wine cellar with biochar/clay plaster walls? Thought you might be interested. I am!

http://www.ithaka-journal.net/pflanzenkohle-als-baustoff-fur-optimales-raumklima?lang=en

Anna

Anna Demb wrote:Hello Dale,

Have you come across this wine cellar with biochar/clay plaster walls? Thought you might be interested. I am!

http://www.ithaka-journal.net/pflanzenkohle-als-baustoff-fur-optimales-raumklima?lang=en

Anna

Thanks for this Anna. Regulates humidity. Good to know.

And adsorbs contaminants!
Anna

Have you got a suggestion for us on how to insulate a rocket stove with local materials (ie not perlite and vermiculite)? We have a lot of experience with earthen building and insulating with local materials like wood shavings, garbage, or goat hair (leftover after taking out the pashmina). Those are great for living spaces and storage spaces, but what could we use in the inner column of a rocket stove? I suppose we could probably get some extraordinarily expensive imported perlite or vermiculite in Delhi, but it wouldn't be a replicable thing in Ladakh.

Looking forward to hearing from some of the expert regulars!

For a simple rocket stove that is used for cooking, the burn tube could probably be placed in a bucket of sand or surrounded by a cob mix.
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I think you are referring to the heat riser in a rocket mass heater - RMH. I don't know of anything that can be gathered, that would work at those temperatures. There ore other types of masonry stove that don't require an insulated riser. This question should be taken over to the wood burning section. There has already been much experimentation on this issue. Do a search with the key words heat riser. You may find that this has already been answered.

Thank you!

I found the print too small in that article, so here it is in our more eye friendly print.

The use of biochar-clay plaster in cellar refurbishment

To achieve a cellar climate best promoting the natural microbial flora that have made their way into the cellar from the vineyard, tests were made at the Delinat Institute on ways of restoring and refurbishing wine cellars in a sustainable manner. One of the main project aspects involved the development of a plaster based on biochar and clay. A new method of application saw the walls of an old Valais wine cellar being sprayed with a 10 cm thick layer of the new biochar-clay plaster (see photo). This massive wall coating provides not only good thermal insulation and consequently fewer temperature fluctuations, but is also a great humidity regulator.

Spraying the cellar's rough stone wall with the biochar-clay mixture.

In combination with the right ventilation, the machine-sprayed plaster made of clay and biochar is able to keep cellar humidity levels at a constant 60 – 80% throughout the year, thus preventing or at least greatly reducing the development of mould and other harmful microbes. At higher humidity levels, the walls quickly adsorb moisture, returning it to the room just as quickly when humidity levels drop. While too high a level of humidity promotes the development of harmful microbes, too low a level is also not beneficial, as it leads to particulate pollution, electrostatic charging of the air and the evaporation of wine in wooden barrels.
The biochar-clay layer of plaster acts as a moisture storage buffer, whereby the capability to adsorb water is dependent on the thickness and quality of the biochar-clay plaster. When high doses of moisture regularly reach the cellar through the earth or by hosing down the cellar, even this buffer will at some stage reach its capacity. This means that the cellar also needs a good natural source of ventilation.

The ingredients of the biochar-clay plaster
To make the spray plaster, 30 – 50% biochar is mixed into the clay, to which a certain amount of sand has been added (compared with normal clay plasters, the sand content is slightly lower). The biochar-clay mixture thus contains 50% biochar, 30% sand and 20% clay. This mixture can also be used as an intermediate layer of plaster, whereby the biochar is ground to less than 5 mm particle size. The result is an anthracite-coloured plaster with a very noble, slightly shimmering appearance. Should a lighter colour be desired, the share of finely ground biochar is reduced to 10-20% for the top layer, and clay-based paint applied as the final coating. No problems have been encountered either with applying the plaster or with its hardening. Compared to lime- or cement-based plasters, the biochar-clay mixture is even beneficial for the hands of the building workers, meaning that gloves and protective clothing are not needed.
It is intended to bring a range of biochar-clay plasters to the market by mid-2013. Up till then, the focus will be on optimising the mixtures and conducting a series of measurements with regard to final solidness, thermal conductivity and water storage capacity.
Biochar can just as well be mixed into conventional lime- or cement-based plasters in equal proportions. In doing so, the biochar can help increase their insulation and water storage capacities. The same applies to rendering. However for plaster, clay is the recommended basic material for achieving an optimal indoor climate.

After applying the intermediate layer of plaster, the biochar gives the plaster an anthracite colour with a slightly shimmering appearance. After the final layer of plaster has been applied, clay-based paints can be used as final coating.

Thanks to its huge surface and porosity, the biochar in the clay plaster helps to adsorb contaminants, spores and mycotoxins as well as helping to bind the gases produced during vinification. The latter aspect means that the moulds and other bacteria lose their feeding grounds. Optimal humidity and the binding of toxins are perfect for promoting healthy microbial flora in the cellar, protecting the wine against sensory deficits. The experience gained in the first winter season in the Valais test cellar shows that the humidity levels have remained constant at 65 – 75%.
The spraying method developed together with the German company, Casadobe, for applying thick layers of biochar-clay plaster can be used both for restoring old cellars and also for refurbishing modern concrete cellars. And of course it can be used for the construction of new cellars. Through the experience gained in this first refurbishment project (to be continued in the coming year with scientific measurements of cellar flora and indoor climate) we hope to have come up with a natural way of optimising a cellar’s climate.


Biochar-clay plaster for use in homes
The biochar-clay plaster technology developed by the Delinat Institute to refurbish wine cellars can also be used for other enclosed spaces, such as food stores, animal housing, warehouses or even houses and offices. Optimal humidity levels have a major influence on the well-being and health of the inhabitants of houses and offices. A humidity level below 40% can lead to dry mucous membranes, in turn increasing the risk of colds, asthma and allergies. Similarly, a humidity level above 70% in closed living spaces results in increased exposure to mould spores. Applying just a 2 cm layer of biochar-clay plaster can noticeably improve a room’s climate. Two Valais houses have already been restored using biochar plaster. First experiences with indoor use have proved to be extremely promising.
If biochar-clay is used as construction material for plaster, insulation or bricks, buildings could partially be recycled after some hundred years as a soil conditioner instead of becoming hazardous waste.

PS.: Biochar-clay plasters also have a shielding effect with regard to electromagnetic radiation (“electrosmog”). This means that we have no GSM reception in the test cellar, a further positive feature allowing us at least there to fully concentrate on working with nature.
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This is great. Everything that I suspected might be true is being tested in those cellars. I've invented many wheels before, and then I find out later that it's been done in some other way. I will follow this with interest. Thank you Anna !

My pleasure!

Dale Hodgins wrote:This same gabion system could be adapted to contain softwood charcoal which is one of nature's best insulators. Charcoal is a very poor conductor of heat and it reflects radiant heat. If plenty of fine ground material were added, it should also be good at preventing convective air currents within the insulation.

Charcoal burns. Wood also burns, so nothing new there with plant derived insulation. It would all be encased under a layer of stucco, so, much like a straw bale wall, there would not be enough air for a fire to take off.

Here's the biggie. Unlike almost every other plant derived insulating material, charcoal is highly resistant to rot. Charcoal has been found in archeological excavations from Roman times even at damp sites in England and Germany. We still want to protect this insulation from water, since accumulated moisture could rot out stucco wire and adjacent wood and the R value would drop hugely for wet material. But the charcoal is not an item that is likely to break down any time soon.

Cellulose insulation which is derived from recycled newsprint is one of the best plant based insulating materials but it is highly susceptible to water damage and rot. Charcoal is less conductive to heat than is wood or paper and it reflects infrared(Heat). Expensive, high tech foam insulating boards incorporate charcoal for this reason. Therefore, charcoal could be used in situations where a high R value per inch plus radiant barrier are desired.

This will be tested along with cob/pumice, sawdust clay, wood chip clay and other insulating materials in small domes of the given material, formed over a huge metal bowl that I'm using so that results may be compared.

I began exploring the idea of charcoal insulation at the beginning of the thread entitled "Dale's Marvellous Inventions and Adaptations." Here's the link. https://permies.com/t/19303/green-building/Dale-Marvellous-Inventions-Adaptations

Check out the thread entitled "Green Building - Materials Testing and Longevity Study Facility - Facades,Roofing,Plasters, Flooring" https://permies.com/t/13262/green-building/Green-Building-Materials-Testing-Longevity – to learn of my plan to run semi scientific short term and long term performance and durability test on various green building products. Others from different regions need to join in this effort if it is to be of value to the majority of natural builders. I'm willing to provide space for those who would like to test certain systems and products on my walls, floors etc...

Sounds good, but there is the issue of spontaneous combustion, which apparently sunk a number of refrigerated ships back when they used this material as insulation:

http://books.google.com/books?id=kw41AQAAIAAJ&pg=PA385#v=onepage&q&f=false

It's not a problem with a bag of briquettes, but quantities of crushed charcoal have been known to ignite when damp. I don't know whether clay slip will diminish that risk.

I poked around a dozen sites concerning spontaneous combustion. I'm pretty satisfied that it's a myth. Here's one --- http://www.nakedwhiz.com/wetcharcoal.htm

I don't know. It seems the link actually makes the case that it can happen to charcoal, just not in 20lb bags.

The way I understand it there is an endothermic or exothermic reaction that happens when water and charcoal are joined, or seperated by evaporation. It seemed each was said, but then the other was said. My chemistry is rusty, so I couldn't discern from the limited info in the link.

So, just like hand warmers, they get warm when oxygen joins to the surface of iron when some activater is present. The release of energy from the oxidizing of the iron gives you the heat. If something similar is possible with charcoal and water, or wet charcoal drying and joining with Oxygen in the air, then it seems reasonable.

And a whole wall of charcoal on the south side of your house, that was getting wet, or got wet and is drying, could possibly cause a fire. Though, even at those conditions, it does sound, based on the link, unlikely. They reference much higher than 100 degrees F for a 20lb bag. For 500-1500lbs on the side of your house it would still have to be heated above 100, and wet/or getting wet, and the moon in just the right alignment.

I do think I would look into it a bit more, or do a large scale experiment(500lbs+ in a 8" thick vertical wall) to see if any conditions could develop elevated heat that a small 20lb bag can't acheive. I'd do that before I'd promote it too much.

As with all good things, deserves looking into. I like the idea, sounds like charcoal has some good properties!

Dale Hodgins wrote:I poked around a dozen sites concerning spontaneous combustion. I'm pretty satisfied that it's a myth. Here's one --- http://www.nakedwhiz.com/wetcharcoal.htm

I already checked the "myth" accounts out. Every one I found had to do with charcoal briquettes in small quantities. Pulverized charcoal in larger quantities (especially when damp, which is likely to occur in insulation through vapor condensation) appears to behave differently, and spontaneous combustion in charcoal has been documented at room temps. The link I posted pertains to incidents involving charcoal as insulation--the precise use you propose. Kind of a bummer too, because I think it's an awesome idea, and apparently it was in widespread use before alternatives were adopted (perhaps because of the risk). Just sayin'--this seems to be a legitimate possibility that should be taken seriously. Here's some more, from

http://www.cozen.com/admin/files/publications/Investigation_and_Analysis_of_Subrogation_Claims_Arising_from_Spontaneous_Combustion_and_Chemically_Induced_Fires.pdf :

"5.Coal and charcoal

For centuries, it has been known that coal and charcoal are susceptible to spontaneous combustion. Various grades of coal absorb oxygen (i.e., oxidize) far more readily than others; those which oxidize more easily have, not surprisingly, a greater tendency to self-heat. Spontaneous ignition seems to occur when there is just enough airflow that the coal is able to absorb most of the atmospheric oxygen, and yet not so much airflow that it carries away the heat that is generated.As with hay, moisture content is a critical factor in the spontaneous combustion of coal and charcoal. The higher the inherent moisture, the greater the oxidizing tendency. Finer particles of coal are more prone to self-ignite, as is freshly mined coal (upon its initial exposure to atmospheric oxygen). While massive quantities of coal are generally required before coal can spontaneously combust, activated charcoal can self-heat in quantities of just several pounds. Moreover, whereas coal will not spontaneously achieve flaming combustion until days or weeks have passed, activated charcoal can ignite in as little as several hours. Ordinary charcoal briquettes are unlikely to self-ignite unless stored in quantities exceeding fifty pounds (22.5 kg)."

What if there were some way to control the exothermic reaction by drawing off heat from dampened charcoal fines before combustion occurs? It would be cool to have heating fuel that never burns up.

We're not going to get any free heat. If a reaction occurs that produces heat and CO2, There will be a loss of some charcoal. When compost produces heat, there is also a loss of carbon. Seems to be the same idea.

I would never consider building anything where I would allow the insulation to get wet. If it were to get wet, we would have a clay covered mess.

Compare this to a straw bale wall. Straw burns. When encased in stucco and plaster, it doesn't burn because the fire can't breathe. Charcoal with the same covering, will not be able to burn, because there is no airflow to maintain a fire.

Yeah, no free lunches. But maybe it would be more efficient than burning, with cleaner emissions (although the CO2 would cause an outcry).

The reason I brought up the dampness was that up here vapor infiltration is problematic with insulation because the temps are constantly below freezing for several months, and frost can condense and accumulate. People here are now experimenting with super thick walls sans vapor barrier, and apparently that can work well if it's done right. I hope so, because I'm looking for an alternative to living in a house suffocated in visqueen. This strategy, however, involves moisture gradually diffusing through the wall, which could certainly dampen charcoal were it used for insulation (which in this climate would need to be voluminous, another prerequisite for spontaneous combustion). The charcoal reportedly doesn't have to be sopping wet for this reaction to occur. I suppose the oxygen starvation would be effective though, by inhibiting not only combustion, but also the reaction itself, since it's an oxidation process. I'm not real paranoid by nature, but the documented cases of shit burning down because something (which has on occasion been charcoal) caught fire all by itself will definitely motivate me to do some rigorous due diligence before I stuff the walls with it. But I hope you're right, because it must be pretty good stuff if they used it on oceangoing ships to insulate frozen meat on long voyages back in the day.

I think charcoal's best use in building might be as an admixture to foam boards and paints. It seems to work well in the wine cellar plaster and it's been used in a thin film on foam as a radiant barrier. If you squeeze it really, really hard you get diamonds. Maybe I'll sell some as diamond feed stock, along with a diagram of the machine required. $50 per pound. That is cheap for diamonds.