Pykrete: What Could Be Done With It

I have had an out of control fetish for Pykrete for a long time. For those that do not know what Pykrete is, it is a mixture of sawdust and ice and its properties combined are just so unique. Bullet proof, cold, slow to melt, easy to form, all natural, amazing ability to float...

I have messed around with it some, but never really found a great use for it. (I tried building a handplane with it, but could not get the embedded nut to hold the frog down enough to keep the plane blade from chattering). Being a visionary I thought perhaps this might be the answer to the problem of uniting the North American Continent with Europe by going over the North Pole with a Pykrete Bridge instead of building one across the North Atlantic with conventional building materials. I mean the building material is partly on site, it is easily repairable, strong, resilient...but lets face it, do will really want a bridge there?

I have wondered if Pykrete would be the ideal building material for off-grid houses needing food refrigeration and/or food freezing. It would be the opposite of a greenhouse, close it up in the summer, and open it wide open in the winter. It has insulating properties, is slow to melt, is indestructible, all natural...

It has been said to never be the smartest person; because when you are, you limit yourself to the potential around you. So I open this up to everyone; what could Pykrete be used for? Surely it has a better use then being made into an aircraft carrier in the North Atlantic! Anyway Pykrete has always intrigued me...

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Pykrete is a frozen composite material made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight (6 to 1 by weight). During World War II, Geoffrey Pyke proposed it as a candidate material for a huge, unsinkable aircraft carrier for the British Royal Navy. Pykrete has some interesting properties including its relatively slow melting rate (because of low thermal conductivity) and its vastly improved strength and toughness over ice; it is closer in form to concrete.

Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process. However, it can be repaired and maintained using seawater. The mixture can be molded into any shape and frozen, and it will be extremely tough and durable, as long as it is kept at or below freezing.

hello . Im manikandan ramesh from puducherry ,india




what happen if a cotton is mixed with ice rather than mixing with saw dust or  wood pulp  ? how stronger and feasible this concept ?



thank you

On Youtube there are videos of people who have made cotton wool Pykrete. Instead of sawdust they used cotton. I wonder if you could use Hemp, carbon fiber, or fiber glass as well? The problem with fiber glass is you would have tons of tiny shards of glass all over after it melts.

I also wonder about how to use it to keep ice, ice for longer. I am thinking like those Ice Castles that they build in Utah during winter. Where they have LED's in them and they are cool looking, but I wonder if you can make them last months longer than when they would normally melt away.

Hi Erik,
Welcome to Permies. I think you might be on to something about mixing sawdust to make the ice castle last longer. Unfortunately it might also make the ice castle look visually a lot different. Sawdust mixed in would make the ice more opaque and perhaps less stunning than pure ice.

Erik London wrote:On Youtube there are videos of people who have made cotton wool Pykrete. Instead of sawdust they used cotton. I wonder if you could use Hemp, carbon fiber, or fiber glass as well? The problem with fiber glass is you would have tons of tiny shards of glass all over after it melts.

I also wonder about how to use it to keep ice, ice for longer. I am thinking like those Ice Castles that they build in Utah during winter. Where they have LED's in them and they are cool looking, but I wonder if you can make them last months longer than when they would normally melt away.

I quite like the idea of cotton wool reinforcement. I think  the fibres would give the ice more strength - although this would be dependent on the direction. Actually shorter lengths might be better as they could flow better with the water before freezing, so maybe waste cotton from mills could be used, rather than processed long length cotton. I used to study composite materials and there is usually a maximum length of fibre beyond which the material doesn't get any stronger.
As you say, there are downsides of using something like glass for ice sculptures, but cotton would probably be nice and white. I don't know how translucent it gets in ice.
It would make an interesting building material for areas with prolonged freezing conditions, enabling year round housing....although humans would probably find i a bit damp. Maybe cold cellars or emergency shelters though.

Hi Erik,

Welcome to Permies.