digplanet beta 1: Athena
Share digplanet:

Agriculture

Applied sciences

Arts

Belief

Business

Chronology

Culture

Education

Environment

Geography

Health

History

Humanities

Language

Law

Life

Mathematics

Nature

People

Politics

Science

Society

Technology

A slab of pykrete
Pykrete is made of 14 percent sawdust and 86 percent water by weight.
Construction of a Pykrete-reinforced ice dome by Eindhoven University of Technology.

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). Its use was proposed during World War II by Geoffrey Pyke to the British Royal Navy as a candidate material for making a huge, unsinkable aircraft carrier. Pykrete has some interesting properties, notably 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 moulded into any shape and frozen, and it will be extremely tough and durable, as long as it is kept at or below freezing.

History[edit]

Geoffrey Pyke managed to convince Lord Mountbatten of the worth of his project (actually prior to the invention of pykrete) some time around 1942, and trials were made at two locations in Alberta, Canada. The idea for a ship made of ice impressed the United States and Canada enough that a 60-foot (18 m)-long, 1,000-ton ship was built in one month on Patricia Lake in the Canadian Rockies. It was, however, constructed using plain ice (from the lake), before pykrete was considered. It took slightly more than an entire summer to melt.

Plain ice proved to be insufficiently strong. Pyke learned from a report by Herman Mark and his assistant that ice made from water mixed with wood fibres formed a strong solid mass—much stronger than pure water ice. Max Perutz later recalled:

Then, one day, Pyke handed me a report that he said he found hard to understand. It was by Herman Mark, my former professor of physical chemistry in Vienna, who had lost his post there when the Nazis overran Austria, and found a haven at the Polytechnic Institute of Brooklyn. As an expert on plastics, he knew that many of them were brittle when pure, but could be toughened by embedding fibres such as cellulose in them, just as concrete can be reinforced with steel wires. Mark and his assistant, Walter P. Hohenstein, stirred a little cotton wool or wood pulp—the raw material of newsprint—into water before they froze it, and found that these additions strengthened the ice dramatically. When I had read their report, I advised my superiors to scrap our experiments with pure ice and set up a laboratory for the manufacture and testing of reinforced ice. Combined Operations requisitioned a large meat store five floors underground beneath Smithfield Market, which lies within sight of St. Paul's Cathedral, and ordered some electrically heated suits, of the type issued to airmen, to keep us warm at 0 °C (32 °F). They detailed some young commandos to work as my technicians, and I invited Kenneth Pascoe, who was then a physics student and later became a lecturer in engineering at Cambridge, to come and help me. We built a big wind tunnel to freeze the mush of wet wood pulp, and sawed the reinforced ice into blocks. Our tests soon confirmed Mark and Hohenstein's results. Blocks of ice containing as little as four percent wood pulp were weight for weight as strong as concrete; in honor of the originator of the project, we called this reinforced ice "pykrete". When we fired a rifle bullet into an upright block of pure ice two feet square and one foot thick, the block shattered; in pykrete the bullet made a little crater and was embedded without doing any damage. My stock rose, but no one would tell me what pykrete was needed for, except that it was for Project Habakkuk.

I Wish I'd Made You Angry Earlier[1] Perutz, Max

Perutz would later learn that Project Habakkuk was the plan to build an enormous aircraft carrier, actually more of a floating island than a ship in the traditional sense. The experiments of Perutz and his collaborators in Smithfield Meat Market in the City of London took place in great secrecy behind a screen of animal carcasses.[2][3][4] The tests confirmed that pykrete is much stronger than pure ice and does not shatter, but also that it sags under its own weight at temperatures higher than −15 C.[5]

Mountbatten’s reaction to the breakthrough is recorded by Pyke's biographer David Lampe:

What happened next was explained several years after the war by Lord Mountbatten in a widely-quoted after-dinner speech. "I was sent to Chequers to see the Prime Minister and was told he was in his bath. I said, 'Good, that's exactly where I want him to be.' I nipped up the stairs and called out to him, 'I have a block of a new material which I would like to put in your bath.' After that he suggested that I should take it to the Quebec Conference." The demonstration in Churchill's steaming bath had been most dramatic. After the outer film of ice on the small pykrete cube had melted, the freshly exposed wood pulp kept the remainder of the block from thawing.

Pyke, the Unknown Genius[6] Lampe, David

Another tale is that at the Quebec Conference of 1943 Mountbatten brought a block of pykrete along to demonstrate its potential to the entourage of admirals and generals who had come along with Winston Churchill and Franklin D. Roosevelt. Mountbatten entered the project meeting with two blocks and placed them on the ground. One was a normal ice block and the other was pykrete. He then drew his service pistol and shot at the first block. It shattered and splintered. Next, he fired at the pykrete to give an idea of the resistance of that kind of ice to projectiles. The bullet ricocheted off the block, grazing the trouser leg of Admiral Ernest King and ending up in the wall. According to Perutz's own account, however, the incident of a ricochetting bullet hitting an Admiral actually happened much earlier in London and the gun was fired by someone on the project—not Mountbatten.[7]

Despite these tests, the main Project Habakkuk was never put into action because of limitations in funds and the belief that the tides of the war were beginning to turn in favour of the Allies using more conventional methods.[8]

According to the memoirs of British General Ismay:

A good deal of consideration, much of it highly technical, was also given to the feasibility of building floating platforms which could either be used by fighters to support opposed landings until such time as airfields ashore were available, or act as staging points for ferrying aircraft over long distances. The idea as originally conceived by a member of Combined Operations staff, and vehemently supported by Mountbatten, was that these floating platforms should be constructed out of icebergs. They would be provided with engines which would enable them to steam at slow speed, and with refrigeration plants to prevent them melting. They would be unsinkable. The whole thing seemed completely fantastic, but the idea was not abandoned without a great deal of investigation. Various alternative methods of construction were then considered by the United States naval authorities, but in the end there was general agreement that carriers and auxiliary carriers would serve the same purpose more effectively."

The Memoirs of Lord Ismay[9] Ismay, General Lord
A Pykrete-reinforced ice dome.

Since WWII pykrete has remained a scientific curiosity, unexploited by research or construction of any significance. New concepts for pykrete however crop up occasionally among architects, engineers and futurists, usually regarding its potential for mammoth offshore construction or its improvement by applying super-strong materials such as synthetic composites or Kevlar.

In 1985, pykrete was considered for a quay in Oslo harbour. However, the idea was later shelved, considering pykrete's unreliability in the real-world environment.[10] Since pykrete needs to be preserved at or below freezing point, and tends to sag under its own weight at temperatures above -15 C, an alternative was considered that would guarantee effectiveness and public safety.[5]

In 2011, the Vienna University of Technology successfully built a pykrete ice dome, measuring 10 metres in diameter. They improved on an original Japanese technique of spraying ice on a balloon by utilizing the natural properties of ice and its strength. This structure managed to stand strong for three months before solar radiation started melting the ice, rendering the structure unreliable.[11]

In 2014, the Eindhoven University of Technology worked on a pykrete architecture project in Juuka, Finland, which included an ice dome and a pykrete scale model of the Sagrada Familia.[12] Their attempt to build the largest ice dome in the world was partially unsuccessful when the dome collapsed within a few days of it being open to the public. Due to human error, the plug to a generator that kept the balloon inflated was pulled, leading to the balloon deflating. The team of Dutch students quickly re-inflated the balloon, and resprayed the part of the dome that had collapsed. They continued with their progress, and eventually opened the dome to the public, where within a matter of days the roof caved in. Luckily, there were no visitors on the site during this time.[13]

In Japan, ice domes have been built using a construction method in which water is sprayed onto a balloon. Researcher Johann Kollegger of Vienna University of Technology thinks his team's new method is easier — for instance, when spraying water onto the balloon, the ice sprays back at the workers. To build their freestanding structure, Kollegger and his colleagues first cut an 8-inch- thick (20 centimeters) plate of ice into 16 segments. To sculpt the segments to have dome-like curve, the researchers relied on ice's creep behavior. If pressure is applied to ice, it slowly changes its shape without breaking. One of the mechanisms by which glaciers move, called glacial creep, functions similarly, the researchers say.[11]

Durability[edit]

The durability of pykrete is up for debate. Perutz has estimated a crushing strength value of around 1,100 psi (7.6 MPa).[8]

A September 1943 proposal for making smaller pykrete vessels included the following table of characteristics:[14]

Comparative properties of materials
Mechanical properties Ice Concrete Pykrete
Crushing strength [MPa] 3.447 17.240 7.584
Tensile strength [MPa] 1.103 1.724 4.826
Density [kg/m³] 910 2500 980

In the media[edit]

In 2009, the Discovery Channel program MythBusters episode 115 tested the properties of pykrete and the myths behind it. First, the program's hosts, Adam Savage and Jamie Hyneman compared the mechanical properties of common ice, pykrete and a new material specially created for the show, dubbed "super pykrete", using newspapers instead of woodpulp. Both versions of pykrete indeed proved to be much stronger than the chunk of ice, withstanding hundreds of pounds of weight. The super pykrete was much stronger than the original version.

The MythBusters then built a full-size boat out of the super pykrete, naming it Yesterday's News, and subjected it to real-world conditions. Though the boat managed to float and stay intact at speeds of up to 23 miles per hour (37 km/h), it quickly began to spring leaks as the boat slowly melted. After twenty minutes the boat was deteriorating, and the experiment was ended. The boat lasted another ten minutes while being piloted back to shore. Though the boat worked, it was noted that it would be highly impractical for the original myth, which claimed that an entire aircraft carrier could be built out of pykrete.[15] Their conclusion was "Plausible, but ludicrous", since it would involve building vessels out of tens of thousands of tons of the material that would sink without being kept cool.

The MythBusters test was done at or slightly above freezing temperatures and generally proved that pykrete as a material was not better than other alternatives. Their vessel did not contain refrigeration units keeping the pykrete cold as the original plans called for and the boat had a much thinner construction than the ships proposed in World War II.

In 2010, the BBC program Bang Goes the Theory episode 26 tested a 20-foot, 5-tonne Pykrete boat made with hemp rather than woodpulp.

All four presenters, Jem Stansfield, Dallas Campbell, Liz Bonnin and Yan Wong had to be rescued from Portsmouth Harbour after the boat took on water through the engine mounts and eventually capsized after melting much faster than anticipated in the warmer than expected September waters.

See also[edit]

Footnotes[edit]

  1. ^ Perutz, 2002, p83.
  2. ^ Gratzer, Walter (2002-03-05). "Max Perutz (1914–2002)" (PDF). Current Biology 12 (5): R152–R154. doi:10.1016/S0960-9822(02)00727-3. Retrieved 2008-01-12. 
  3. ^ Ramaseshan, S (2002-03-10). "Max Perutz (1914–2002)". Current Science (Indian Academy of Sciences) 82 (5): 586–590. ISSN 0011-3891. hdl:2289/728. 
  4. ^ Collins, Paul (2002). "The Floating Island". Cabinet Magazine (7). doi:10.1016/S0960-9822(02)00727-3. Retrieved 2008-01-12. 
  5. ^ a b "Max Perutz OM". The Daily Telegraph. 2002-02-07. Retrieved 2008-01-12. 
  6. ^ Lampe, 1959, p136.
  7. ^ Perutz, 2002
  8. ^ a b Perutz, M. F. (1948). "A Description of the Iceberg Aircraft Carrier and the Bearing of the Mechanical Properties of Frozen Wood Pulp upon Some Problems of Glacier Flow". The Journal of Glaciology 1 (3): 95–104. 
  9. ^ Ismay 1960, p319.
  10. ^ Breeze, Paul (1985-08-01). "A New Chip Off an Old Block". The Guardian. p. 13. 
  11. ^ a b http://www.livescience.com/11704-austria-imbibe-ice-dome.html
  12. ^ "Sagrada Familia in ice". structuralice.com. Retrieved 18 October 2014. 
  13. ^ http://yle.fi/uutiset/maailman_suurimman_jaakupolin_katosta_romahti_pala_juuassa/7056718
  14. ^ The National Archives, ADM 1/15677 – Proposals and inventions of Mr Geoffrey Pyke; gravity propelled ball bomb, pykrete and power driven rivers.
  15. ^ Royal Naval Museum Library, 2001. http://www.royalnavalmuseum.org/info_sheets_Habbakkuk.htm

References[edit]

  • Ismay, General Lord (1960). The Memoirs of Lord Ismay. Heinemann. 
  • Lampe, David (1959). Pyke, the Unknown Genius. London: Evans Brothers. 
  • Perutz, Max. "A Description of The Iceberg Aircraft Carrier [1948]". In Gerald Seligman. The Journal of Glaciology. Volume I (January 1947 - October 1951). The British Glaciological Society. 
  • Perutz, Max (2002). I Wish I'd Made You Angry Earlier (paperback ed.). Oxford University Press. ISBN 0-19-859027-X. 

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Pykrete — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
2051 videos foundNext > 

MythBusters - Pie-crete

New episodes return Wednesday, Oct. 7th @ 9pm E/P on Discovery! Check out exclusive footage straight from the MythBusters' own video cameras: http://dsc.disc...

PYKRETE BULLETS & Ice Shotgun Bullets

Pykrete was invented during WW2 as an alternative material to build ships with. It seems crazy but it worked very well in testing. It was nearly bullet/bomb/...

Shooting Pykrete

Mike Fletcher makes up a batch of "Pykrete" a mixture of sawdust and water, when frozen, is said to be stronger than concrete so he shoots it with a rifle to...

Pykrete Ammo: Destruction Potential?

Link to raffle: http://www.theslingshotforum.com/f4/vote-next-target-win-rambone-34075/ ----------------------------- When we shot Ice as ammo, it was not po...

Pykrete Dome Time Lapse

Timelapse of the construction of the world's largest ice dome. The timelapse was created by monitoring their webcam feed from the 10th of January 11:30 until...

Melting Pykrete block at full and half concentration, versus plain ice cube

Ethan's Science Fair 2014. This was our first attempt at comparing the relative melting rates of Pykrete and plain ice. The results are a little inconclusive...

boat made of ice and newspaper.avi

An Investigation into Pykrete

An Investigation into Pykrete, Ice and Paperkrete. Seeing how much weight can they hold before that break.

Ice Boat Sets Sail on Solent and Sinks - Bang Goes The Theory, Series 3 Episode 6 - BBC One

http://www.bbc.co.uk/bang Follow Bang on Twitter @bbcbang and #bbcbang Jem Stansfield launches his ice boat in a mission to sail across the Solent estuary be...

Pykrete (Mr Bell is back with a bang)

Okay, so it has been a while since Mr Bell uploadsd a video, but he is back with quite a good one. Pykrete, as it turns out, is pretty strong stuff, strong e...

2051 videos foundNext > 

218 news items

The Fiscal Times

The Fiscal Times
Fri, 06 Feb 2015 12:26:41 -0800

The past two years have been very good to John Oliver. Following an excellent spell behind Jon Stewart's desk in the summer of 2013, Oliver was presented with the opportunity to host his own show on HBO and he seized it with both hands. At first blush ...

University Herald

Gizmag
Fri, 06 Jun 2014 15:38:01 -0700

How do you top building the world's largest ice dome? Well, if you're the Eindhoven University of Technology, you build a 40-meter (131-ft)-high model of Barcelona's Sagrada Familia basilica ... and you build it it out of "pykrete." A team of over 50 ...
 
Wired
Sat, 05 Jan 2013 03:26:15 -0800

If so, we'd like to humbly suggest that you consider pykrete for all your snow fort construction needs. Pykrete is a composite material made of a mixture of wood pulp and ice. Named for its inventor Geoffrey Pyke, pykrete was an experimental material ...

Eos Wetenschap

Eos Wetenschap
Mon, 02 Feb 2015 04:19:55 -0800

Het bouwwerk in Finland is uniek want bouwen met pykrete wordt niet veel gedaan, ondanks de lange geschiedenis van het materiaal. Het was uitvinder Geoffrey Pyke die pykrete in de Tweede Wereldoorlog bekendheid gaf. Hij had het plan om er voor de ...
 
Black Heart Gold Pants
Wed, 21 Aug 2013 16:30:43 -0700

I remember camping nights being fun and also that the one Regalia we attended was amazing for how many people were there, but the one thing we did during Cub Scouts that always sticks out in my mind as amazing was the time we built a pykrete canoe.
 
Cobouw
Mon, 24 Nov 2014 06:15:00 -0800

Daarnaast breekt het heel makelijk in stukken (lage ductiliteit). Ter verbetering van de eigenschappen kunnen houtvezels aan het ijs worden toegevoegd. IJs met houtvezels heet ook wel pykrete. Voor de constructie van de Sagrada Familia wordt ook ...
 
Studio040
Fri, 20 Feb 2015 04:56:15 -0800

Na de Solar Challenge en de Pykrete Dome stort een groep studenten van de TU/e zich op een nieuw avontuur: meedoen aan de 80 Day Race. Nieuwe elektrische TU/e motor racet om de wereld in 80 dagen. Het een race voor elektrische voertuigen ...
 
Architectenweb
Fri, 30 Jan 2015 07:33:45 -0800

Afgelopen zaterdag is in het Finse Juuka de Sagrada Familia van ijs geopend. Hoewel het bouwwerk niet geheel kon worden voltooid, is het team van de TU Eindhoven er wel in geslaagd de hoogste torens te realiseren die ooit van ijs zijn gebouwd.
Loading

Oops, we seem to be having trouble contacting Twitter

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!

Searchlight Group

Digplanet also receives support from Searchlight Group. Visit Searchlight