WI: Ancient/medieval pykrete?

Arkenfolm

Pykrete (or pycrete) is a mixture of ice and wood pulp which produces a substance which when frozen is as strong as concrete and melts much slower than regular ice. It was proposed by Geoffrey Pyke during WWII and became most famous as the material the massive Project Habakkuk carrier/floating airfield was to be built out of. However, the substance seems to be relatively simple to manufacture--it requires a source of cellulose (like wood pulp) and a source of ice. While the Industrial Revolution made the production of wood pulp much easier, there's nothing about pykrete which prevents a premodern civilisation from manufacturing it. The difference would be the lack of standardisation since the wood pulp/cellulose will come from a variety of sources depending on region and manufacture, but overall this shouldn't make it much weaker than the modern substance and it will still be stronger/more resilient than normal ice.

Pykrete also is not known for having many uses, but in premodern times the key use would be refrigeration. Since it melts much slower than regular ice, pykrete could be manufactured and transported all year easier than ice assuming there's a good source of ice nearby. Conveniently, civilisations from the Middle East to Europe to China to the Andes have snow-capped mountains all around them. IOTL, ice was harvested from these mountains and transported to the wealthy.

So could pykrete be invented sometime before the 16th century anywhere in the world and what might the effects be? More importance to mountainous regions and the countries which control them? More availability of iceboxes/icehouses/etc. leading to better public health and more diverse cuisine? More complex architecture in places like Scandinavia thanks to better scaffolding? Something more exotic like a sort of armour (for vehicles or people) used by northern countries? An alt-Project Habakkuk aircraft carrier is built in TTL's 20th century? Or even icebreakers? Or would premodern pykrete simply end up just another way of ice harvesting?
 

Arkenfolm

Dave Shoup said:
The wood pulp/sawdust has to be mixed with (liquid) water, and then frozen. Challenging to get that on demand, absent refrigeration.
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Sounds like the solution would be bringing the water higher up the mountain and into some shade and/or waiting until nightfall.
 
Dolan

Dolan

Banned
Amusingly, if sea water could be used, I could see Scandinavian/Russian fortifications built by piling blocks of frozen sawdust/wood pulp water. Also would be dominant fortification material in alt-Canada and Alaska.
 

Deleted member 114175

I could see pykrete used as a material to aid refrigeration in yakhchals. Other uses will be difficult because it will melt too easily in any place that doesn't have an abundance of solid ice already.
 

Circonflexe

Of course, since it melts slower than regular ice, this means that it absorbs heat less well than ice, and therefore that it is a worse refrigerant. (It could however still have a slight use as a thermic insulator).
 

Orcot

Could pykrete be invented before 1600. Sure Would it helpwith public health , probably not, ice houses do not leave wood dust in your food, the wood dust might also be suseptable to fungi/rodents that clean ice is not. Pasteurisation and creating oxygen poor enviroments might be easier to accomplish.
As a building material? It's going to be a temperal winter habitat, you could not build siege equipment out of it as no wars are fought in freezing tempratures.
Artisians could perhaps use it as a cheap alternative to practise sculpting.
If it exists someone will find a use for it.
Thinking far outside the box someone might use it as a cast, to make prototypes, build little boats out of it and see the general float designs see what little differences do with kiel design etc that would however be quit a modern mind set. still tough you can figure out the basics of the bow wave, best bow design, draft etc.
 
Workable Goblin

Workable Goblin

Circonflexe said:
Of course, since it melts slower than regular ice, this means that it absorbs heat less well than ice, and therefore that it is a worse refrigerant.
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Not necessarily. It could simply have a higher heat capacity or enthalpy of fusion, either of which would slow down the melting process by requiring a greater energy input to reach melting temperature (in the former case) or to actually melt (in the latter). It seems that you are correct that it has a low thermal conductivity (i.e. ability to absorb heat), but the mere fact of it melting slower does not establish it.
 
ModusViv

ModusViv

Dave Shoup said:
The wood pulp/sawdust has to be mixed with (liquid) water, and then frozen. Challenging to get that on demand, absent refrigeration.
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Dave Shoup said:
Pumping water uphill in a pre-industrial era isn't the simplest task in the world, either.
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Not sure how efficient this is, but - would it be possible to bring the wood pulp to a higher elevation, or even set up operations in a high elevation (making the pulp out of conifers, say), melt snow and ice (if there's wood for pulp, there's wood for fire), and mix the resulting ice water with the pulp to make the pykrete? Of course, now you have to transport it down the mountain.

Or, maybe it could be retained at altitude? How is the traction of the material? Could it be used to build roads over high mountains? Maybe a nice broad elephant highway over the Alps?
 

Dave Shoup

Banned
ModusViv said:
Not sure how efficient this is, but - would it be possible to bring the wood pulp to a higher elevation, or even set up operations in a high elevation (making the pulp out of conifers, say), melt snow and ice (if there's wood for pulp, there's wood for fire), and mix the resulting ice water with the pulp to make the pykrete? Of course, now you have to transport it down the mountain.

Or, maybe it could be retained at altitude? How is the traction of the material? Could it be used to build roads over high mountains? Maybe a nice broad elephant highway over the Alps?
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Given enough manpower, I suppose so, but given the abilities demonstrated in the ancient world when it came to construction and engineering using wood, stone, and concrete, I'd have to ask why?
 

Circonflexe

Workable Goblin said:
Not necessarily. It could simply have a higher heat capacity or enthalpy of fusion, either of which would slow down the melting process by requiring a greater energy input to reach melting temperature (in the former case) or to actually melt (in the latter). It seems that you are correct that it has a low thermal conductivity (i.e. ability to absorb heat), but the mere fact of it melting slower does not establish it.
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Per mass unit, it almost certainly has a *lower* enthalpy of fusion and heat capacity than water, since it is water mixed with other stuff (cellulose), and water is quite extreme with respect to those two properties. (To be honest there *could* also be some chemical interaction between the water and cellulose, but these are very limited, or else cellulose would depolymerize into glucose — which, if it happens, takes a long time [citation needed]).
 
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