Primitive Technology: Wood Ash Cement – Creating wood ash cement from scratch
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Partial credit for this idea goes to James Keane who I discussed this with on my wordpress site (see conversation): https://primitivetechnology.wordpress.com/2018/03/06/lime/#comment-9736
I developed an experimental cement from made only from re-fired wood ash as its cementitious material. It was mixed with crushed terracotta as an aggregate and formed into a cube. The cement set hard after 3 days and did not dissolve in water after this period.
Process: First I burnt bark and leaves in a kiln at high temperatures to produce well burnt, mostly white wood ash. The ash was then mixed into water and stirred well. The excess water was poured off and the resulting paste was made into pellets and allowed to dry. A pellet was then re-heated in the forge until it glowed about orange hot. This was then taken out, cooled and dropped in a pot of water. The pellet dissolved and boiled due to a chemical reaction with the water. The paste was stirred and crushed terracotta (old tiles from previous projects) was added and mixed to form a mouldable mortar. This was formed into a cube and allowed to set for three days (in the video, a cube made exactly the same way 3 days previously was used due to time constraints). The resultant cube was strong and made a slight ringing sound when tapped with a finger nail. It was placed in water for 24 hours to simulate a very heavy rain event and did not dissolve or release residues into the water.
My current theory: The main component of wood ash consists of calcium in some form (e.g. calcium carbonate, calcium oxide). This can be up to 45% from my research. Calcium is in higher concentration in the bark and leaves of a tree. When the ash is mixed with water, the soluble component of wood ash (10% pot ash) dissolves into the water. But seeing that it does nothing for the cementing process, it is drained off leaving the insoluble calcium (and other components) in the paste. Doing this probably raises the relative percentage of calcium in the paste to about 50% or more. Most of the other 50 % consists of silica and alumina which are pozzolans, materials that chemically react with calcium hydroxide to increase the durability of the cement product. The paste was then made into a pellet and fired again to high temperature to convert all the calcium compounds to calcium oxide. It also reduces any charcoal in the pellet to ash if it hadn’t already been burnt the first time. This step seemed important as un-fired ash pellets only partially hardened and would fall apart in water, though retaining a weak undissolved 5mm thick crust. I can only surmise that re-firing the ash just gave a greater conversion of the calcium components to calcium oxide. The pellet is slaked in water converting the calcium oxide to calcium hydroxide. This cement was mixed with crushed terracotta which may also help in some way that I’m not aware of as I only did this one experiment and did not test other aggregates yet (e.g. sand, gravel etc.). Terracotta is porous and might hold together better than other materials. The mixture is allowed to set in air where carbon dioxide reacts with calcium hydroxide to form calcium carbonate cementing the aggregate together. After this, the cement will not dissolve in water.
Use: I think this material might have a potential use as a mortar holding rocks or bricks together in wet environments where limestone or snail shells are unavailable for making cement. Wood ash is a pretty ubiquitous material to most natural environments inhabited by people using biomass fuels. Wood ash cement turns a waste product into a valuable building material. From my research, wood ash is already being used as a partial replacement for cement in the building industry without decreases in strength of the final product. But I’ve only just started experimenting with it and don’t know its full capabilities and limitations. Calcium content of wood ash differs depending on the species of tree, the part of the tree burnt and the soil it’s grown on. Cautious experimentation is still required before committing to a hut built from this material.
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I think I have the chemistry right. If any chemists are watching correct me if I'm wrong. The calcium compounds are converted to calcium oxide in the second firing, turn to calcium hydroxide in the water and then set to calcium carbonate in the air. There maybe a pozzolanic effect due to the alumina and silica in the ash too. The end product is a cube made only from wood ash (fired twice) and crushed pottery. It sets hard after 3 days and will not dissolve in water even when fully submerged for 24 hours. Thanks.
Genial.
What A High Skill Survival You Have It, Man!
Whats the name stone reds..primiteve thecknologi…..please
Not exactly relevant to making concrete, but how did you cut that circular stone at 2:37? You should make a millstone to help with crushing/grinding all your materials
Great, I will use this on my crafting table xD
How dp you scavenge for clay?
It would be nice if he would have words appear and say what the rock he used probably is
That's It. I'm going to build a house.
Okay this already make cement, soon enough he will make copper iron steel then vibranium…
The OG asmr channel
How long until the mortar and pestle
If you're trying to get a higher concentration of ash in the water a good method would be to mix it in while heating the water over a fire. This should allow for more ash to mix in, and will leave the solution supersaturated once it cools. I could be wrong, this is just based off of the stuff I was taught in chemistry class a couple years ago.
This the OG wilderness survival guy ❤️
А теперь представьте, что его найдут австралийские аборигены?!
Да он у них королем станет.
Try to reduce the water as much as you can because it will make your concrete as hard as possible. Also, soak it in water in few days for curing.
I know what I’m doing in the holidays
Before you start building some tower, I just want to tell you that the height limit is only 256 blocks.
wait thats not wood.
5 years from now he will be manufacturing a nuclear reactor
اإن مكرر نننة أو نلنلتقبعد د طو كويس مكنتش كسض
Is this channel sponsored by Donald Trump?
Cause your forest is like a private place for you
Clay
Watch with subtitles on. You are welcome
Id love to survive with this guy
Amazing!
Forgive my ignorance and possibly stupid question. But whats the brown stuff you mixed it with? Just dirt? Some sort of stone? TIA lads.
Ash only ? Can other trees be used ?
Can we build a pool with it?
vietnam hello guys .. you guys come to my channel to support me, thank you
Awesome as always.
This channel will become medieval,-how to build a castle-
How to make iron knight armorHow to abortHow to make diamond armorHow to be the king of a castleA… S… M… R… Survival
The Asia already knew this and that's why you pick it up and are trying to take away it away as your discovery the cool mines no this already too .stop stealing WHAT other people invented.
Nature is trying to do a ASMR
Hay alguna formula ignífuga con tierra normal?
That does not make alot from all that ash
If you watch these videos without captions you probably got bad teeth and body odor
우와! 신기방기.
근데 한국인은 없나?
Une fois qu'on a fait la boulette de cendre, il faut la faire cuire sur le feu ?
melhor canal mano ensina muita coisa
The OG. I always come back.
@2:20 you must have fingers of steel…
I made one today and hopefully it doesn’t crack
Sir I respect your hard work
What is the orange red thing
Take u a year to make the front step