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wood ash and soil cement

 
pollinator
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does anyone know about this???

i've been reading about ash, making soil cement mixes, and lime mortar for a couple of weeks now. its just come to me thats its a good idea, to put wood stove ashes in there, though i never thought about it before ... i am trying to understand what the ash is about, different ashes, and research about making old school simple cement/concrete. ah and the moisture barriers, when and where to use.

i've already been using the search feature here, and google - and located some good stuff that cleared up some ideas for me...well now i got a lot of ideas stewing in my head anyway, i think i got a grip on what i am doing =) or at least enough research for now, sun is shining.

http://www.permies.com/t/4839/green-building/Building-lime#42222

http://www.permies.com/t/5882/green-building/alternative-foundations-flooring

(plus i just learned about gabions, thanks permies!)

of course its all about the local soil, if it contains lime already, sand or clay - so you have mix a totally different mix for each place and add some purchased stuff.
i am thinking to stretch a couple of bags of cement and lime mortar really really far by making some soil cement and experimenting with adding wood ashes.
my small project, well its kinda amorphouos atm. but i got the area prepared and that took a long time of digging and making berms.

basically i am making a patio kind of space, with a a sink area and some water hoses. and putting up some privacy screens and such.....

i want the bottom and the sides to be cement like...but without using cement. or at least not using much cement.
i am going to use soil cement, sand and gravel, and a tiny bit of lime, with a good amount of ashes and experiment.
and to make some forms too.... then put all the blocks together into a soil cement mix....

also found this in a search, which has a reference to making cement with wood ashes, as well as a whole lot of interesting recipes.

link:
http://www.mspong.org/cyclopedia/cements.html


i figure i would just ask anyone who might be inclined to share some info- if they tried this, working with soil cement- or at least thought about it.


and what does anyone think about using wood ashes for an earthen plaster?
i'm gathering now that you need the lime, to mix with the ashes...so the lime is more of the key thing than the ashes.
but it could be a very very small amount of lime for it to be effective, and make the material more cement like?
alot of building mixes that you can buy have a small amount of lime, as well as lot of other things in there....


Staff note (Glenn Herbert):

"Wood ash cement" link is broken. Here is the correct current link: http://www.mspong.org/household_cyclopedia/cements.html The reference has lots of other interesting 19th century recipes.

 
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I found an extract of a study which examines using wood ash to make concrete material: http://www4.uwm.edu/cbu/abstracts/03-513.pdf
 
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Sorry for the resurrection of this old post.

I too have been looking into wood ash as a clay substitute and mortar binder.

Here is a video by Primitive Technology on wood ash bricks:

https://youtu.be/DP0t2MmOMEA

Ok, here's my thought...

Sift the ash for fine particles and much less organics. Wet it and mix, and drain like in the video. Instead of refiring it, add straw for a cob-like mix. You could also make the mortar out of it to build a stone based rocket mass heater and the ash-cob as a covering.

Thoughts?
 
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Location: Colorado
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The reason that Prim re-fired was to calcine the calcium in the ash... no pun (not really)

The decanting that he did floated away the LOI (loss on ignition - unburned charcoal).

His video is a little misleading - and this thread has some issues related to it.

Generally (GENERALLY!!) Wood Ash is primarily Calcium and Silicon (with metals - primarily Aluminum) and that is mostly (MOSTLY!!!) the same as Portland Cement.

Wood Ash in general is chemically identical (IN GENERAL!) to Ordinary Portland Cement.

Yes.

Why doesn't your fire-pit turn to a cement block? Metastable Crystalline Structure!!

When OPC clinker comes out of the kiln, it has to be rapidly cooled, or the crystals in it grow into more stable forms and combine with humidity to create expensive, sterile, and caustic sand/gravel/dust - ash.
Wood fires cool slowly, so the ash becomes hydrated and stabilized.

Prim's video shows first the fire to make the ash - this is incidental to the process, the first fire doesn't mean much and may as well have been a cooking fire.

The second fire is the key. Before the second fire, he "purifies" the ash by decanting the LOI - this is good. In the second fire, the ash balls that he made glow - this is calcination that drives the CO2 out of what is essentially limestone in the ash (that is produced by the slow cooling - limestone is already carbonated via a chain reaction from hydration to carbonation)

Something missing in his video is that the inner part of the ash-ball is insulated from the air/humidity, so it cools slower than the skin of the ball, and is not converted to a non-reactive (useless) form of Calcium.

Then he adds fired clay dust. Clay is alumino-silicate goodies, and the firing process creates a meta-crystal. Vis Metakaolin as opposed to kaolin. Metastable clay is a Pozzolan... much argument and many Romans....

The most important part here is the RAPID cooling of the ash (again, after it has been made - the first fire is not part of the cement process, all it does is make ash...) Prim did it via a ball of ash, and dropping it in water.

The use of naturally cooled wood-ash in concrete or plaster or mortar adds a little bit of reactive lime (calcium) to the mix - but it is mostly a super-fine filler and to a lesser extent an added Pozzolan (again, Concrete Chem is a field of many dangers!!)

Just mixing Wood Ash into Portland is certainly good - but to replace Portland all together with wood ash requires that the ash be heated to red-glow, then cooled as rapidly as possible. This actually makes it INTO Portland Cement, just with a dirty and uncontrolled recipe.

My plan (and why I'm back here again after a few months of research, experimentation, failure, and re-thought) is to make a diy rotary kiln. Seriously. Get the ash super-hot, then blow huge amounts of air over it without creating a dust-cloud of doom. My mountain has a severe lack of limestone, and my wallet has a severe lack of portland cement :(
 
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Sorry if this looks strange I'm doing on a crappy old andoid phone.

1) is it critical to do the second burn if you are adding to cob or Adobe

2) is it critical to do a second burn to create a breathiable "lime pkaster" from Ash.

I live in the very dry desert and don't have the means to do a second burn safely, even in winter

3( Can you do a second burn without making it into balls

Thanks for reviving this post! I have lots of Ash and my husband thinks in hoarding. I need to have a plan or it's going into the compost.

quote=Spencer Miles]The reason that Prim re-fired was to calcine the calcium in the ash... no pun (not really)

The decanting that he did floated away the LOI (loss on ignition - unburned charcoal).

His video is a little misleading - and this thread has some issues related to it.

Generally (GENERALLY!!) Wood Ash is primarily Calcium and Silicon (with metals - primarily Aluminum) and that is mostly (MOSTLY!!!) the same as Portland Cement.

Wood Ash in general is chemically identical (IN GENERAL!) to Ordinary Portland Cement.

Yes.

Why doesn't your fire-pit turn to a cement block? Metastable Crystalline Structure!!

When OPC clinker comes out of the kiln, it has to be rapidly cooled, or the crystals in it grow into more stable forms and combine with humidity to create expensive, sterile, and caustic sand/gravel/dust - ash.
Wood fires cool slowly, so the ash becomes hydrated and stabilized.

Prim's video shows first the fire to make the ash - this is incidental to the process, the first fire doesn't mean much and may as well have been a cooking fire.

The second fire is the key. Before the second fire, he "purifies" the ash by decanting the LOI - this is good. In the second fire, the ash balls that he made glow - this is calcination that drives the CO2 out of what is essentially limestone in the ash (that is produced by the slow cooling - limestone is already carbonated via a chain reaction from hydration to carbonation)

Something missing in his video is that the inner part of the ash-ball is insulated from the air/humidity, so it cools slower than the skin of the ball, and is not converted to a non-reactive (useless) form of Calcium.

Then he adds fired clay dust. Clay is alumino-silicate goodies, and the firing process creates a meta-crystal. Vis Metakaolin as opposed to kaolin. Metastable clay is a Pozzolan... much argument and many Romans....

The most important part here is the RAPID cooling of the ash (again, after it has been made - the first fire is not part of the cement process, all it does is make ash...) Prim did it via a ball of ash, and dropping it in water.

The use of naturally cooled wood-ash in concrete or plaster or mortar adds a little bit of reactive lime (calcium) to the mix - but it is mostly a super-fine filler and to a lesser extent an added Pozzolan (again, Concrete Chem is a field of many dangers!!)

Just mixing Wood Ash into Portland is certainly good - but to replace Portland all together with wood ash requires that the ash be heated to red-glow, then cooled as rapidly as possible. This actually makes it INTO Portland Cement, just with a dirty and uncontrolled recipe.

My plan (and why I'm back here again after a few months of research, experimentation, failure, and re-thought) is to make a diy rotary kiln. Seriously. Get the ash super-hot, then blow huge amounts of air over it without creating a dust-cloud of doom. My mountain has a severe lack of limestone, and my wallet has a severe lack of portland cement
 
Spencer Miles
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Location: Colorado
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I imagine you can do the re-burn without making it into balls, but it is best to wash out the soluble compounds first (chemistry reasons)

If you don't do the re-burn, it is little better than a filler - has very little reactive capacity without it. Some clay floors have ash, but I don't think that adds much cementing action, just durability (may be wrong).

As for the ash pile - if you have to, bury it everywhere. Make soap. Make it into the ugliest paint in the world...

Desert? 55 gallon steel drum, long stove-pipe with a few metal screens for catching any sparks.

Will = Way if will = try.
 
If you are using a wood chipper, you are doing it wrong. Even on this tiny ad:
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https://permies.com/wiki/bootcamp
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