Primitive Technology: Geopolymer Cement (Ash and Clay)

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Primitive Technology: Geopolymer Cement (Ash and Clay)

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About This Video:
I have made wood ash cement before under the assumption that it was the calcium in the ash that gave it its cementitious properties. It may however be a type of geopolymer cement, where the cement is activated by and acid or a base (in this case a base). The acronym NASH is used to remember the material needed: sodium, alumina, silica and H2O. All of these are present in the materials used here.
I did some experiments to see how to produce the cement using ash and fired clay from broken bricks. The first method was to take ash from a cold fire and form it into pellets. One pellet was left aside to dry while the others were calcined by firing them in a forge with wood. The calcined pellets were then mixed with terracotta in different proportions (ash: clay 1:0, 1:1, 1:2, 1:3). All samples survived a water test after setting for a week except for the sample made from cold ash that had not been calcined. This demonstrates the need to calcine the ash at a high temperature before use.
Next I built a furnace with a grate for calcining ash to prove it could be done with natural draft rather than the more laborious blower method. An ash brick or clinker was made from a cold fire and was placed on the grate and fired. The clinker was then taken out, mixed with terracotta and formed into various shapes. One sample was mixed with sand as an alternative to terracotta. The samples all survived the water test after 2 days of setting though the sand sample isn't as strong as the terracotta ones.
Finally, I took the ash from the furnace and used it as is without forming it into a clinker and calcining it. My theory was that ash from the furnace gets hot enough just from burning on the grate that it does not need further calcining. The ash was mixed as is with terracotta and left to set for only 6 hours. It passed the water test without dissolving suggesting a quick setting time.
These experiments have shown how it might be possible to scale up and simplify the production of ash cement. I'm considering it as an alternative to brick making as it's potentially a simpler method (no brick forming, hours stoking the kiln etc.). The structures would have to be adapted to the new material and might be insitu formed walls. More experiments need to be done.

About Primitive Technology:
Primitive technology is a hobby where you build things in the wild completely from scratch using no modern tools or materials. These are the strict rules: If you want a fire, use a fire stick - An axe, pick up a stone and shape it - A hut, build one from trees, mud, rocks etc. The challenge is seeing how far you can go without utilizing modern technology. I do not live in the wild, but enjoy building shelter, tools, and more, only utilizing natural materials. To find specific videos, visit my playlist tab for building videos focused on pyrotechnology, shelter, weapons, food & agriculture, tools & machines, and weaving & fiber.

#PrimitiveTechnology #GeopolymerCement #cement
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As pointed out by some viewers on my previous cement videos, this material is probably more of a geopolymer than a calcium based cement, or possibly a mix of the two types, based on the materials that are known to be in wood ash and clay. In any case, it's a material that sets after as little as 6 hours and won't dissolve in water afterwards. All three methods shown here will work, the key being that the ash needs to be heated to about 800c plus with lots of oxygen. This was demonstrated by the uncalcined ash sample dissolving, because it was from an ordinary fire that didn't get hot enough to calcine the ash.

primitivetechnology
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Best thing about his videos is the random cutaways to whatever he happens to find. Random lizard? Cool. Crab he found in the river? Nice.

IamSamisMe
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I love how the channel started out as "how to build a survival shelter" and is now "SCIENCE IN THE JUNGLE!" with well documented experiments for others to try out and collaborate on. Makes me want to go out and do clever things with rocks and sticks.

pogostix
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I love that we get occasional asides from the technical work. "Cement, cement, cement ... By the way, this is a friend. Cement, cement, cement..."

gazeboist
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I don't quite understand how watching a person work their ass off can be so relaxing - but this channel continues to be absolutely sublime

dylearium
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Three things: First, a reminder to everyone that John puts captions on all his videos to describe his processes. Make sure they're switched-on to understand his vids!

Second - I've been re-watching the last several videos to try to understand what happened to the ash-insulated furnace from several videos back. You demolished a brick furance to build it, but it seems like the brick furnace is back?

Third - Is there an advantage to sometimes have a wide-mouthed nozzle in your forge and sometimes a flat-mouthed nozzle? If not, it would seem to me the flat-mouthed nozzle should be default, so you can always have the option to use the clay mold when forging your iron ingots.

This channel is exceptional and I can't get enough. Thank you!

raemckay
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7:31 "Ash Clinker on Grate" is such a fire piece of modern art concept I can't even

MrCleks
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I love how he starts the video by reminding everyone that he's the GOAT and just makes fire with his bare hands

qalak
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I will never ever unsubscribe from this channel. Probably the only non fake primitive tech related channel

tripwire
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30 seconds old, and the video's already at several hundred views. Dude's got a dedicated following, that's for sure.

kiltmaster
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I love how this is an exposition on scientific process research and development as it would be done under primitive conditions without the benefit of quantitative measuring methods, and relying solely upon qualitative results. This is experimental archaeology gold right here.

kevinstoneburner
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Dunno if anyone else has ever said this by my kids (7 and 5) love watching your videos over and over. The 7 year old is reading now so she turns on the subtitles and tries to understand. Wife got me your book to show support. My house loves what you do.

one_b
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This is what is actually happening when you're researching a new technology in a strategy game. The game just shows a bar filling up, but in the background there's someone in your settlement doing this kind of thing and sharing the results.

ProvenParadox
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Yes! Can't wait to see what else you've come up with about this stuff.

I was not disappointed! Reducing the need for fired material by using 75% sand is a big improvement.

Nighthawkinlight
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I like how you always show yourself starting a fire. Other "primitive technology" channels would make a cut and light the fire with a lighter. Your dedication is amazing!

Boydar
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So many times when I turn on your videos, I make it nearly to the end before I realize I never turned on the subtitles. So I have an amazing excuse to watch it all over again.

The way you film and cut your work tells the story perfectly. I find your work incredible!

aronweiss
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I think he clearly wants to show people that the most important skill in primitive survival is being able to make fire. Even though he's done it many times he tends to show the whole process.

capc
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Aaaaand the Mud Mage Supreme is at it again with more mud science. I seriously love the time you spend showing us the power of dirt my man.

Alloran
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Твои ролики - прямо как бальзам на душу, очень успокаивают и помогают абстрагироваться от всех новостей, и ты отлично делаешь это, как и многие подобные выживальщики-ютуберы. Лайк и уважение твоим роликам, ибо ты умеешь нас отвлечь от всего своим контентом строительства и выживания.

Andrey_Akimov
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John Primitive has been getting pretty buff recently. His crayfish traps have been paying off!

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