Pykrete

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Pykrete is a composite material made of approximately 14 percent sawdust or some other form of wood pulp and 86 percent ice 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 , and its vastly improved strength and toughness over unmodified crystalline ice, actually closer to concrete. Pykrete is slightly more difficult to form than concrete, as it expands during the freezing process, but can be repaired and maintained from the sea's most abundant raw material: water. 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. 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 in two locations in Alberta in Canada. The idea for a ship made of ice impressed the United States and Canada enough that a 60-foot, 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. 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. 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. In 2009, the Discovery Channel program MythBusters 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 proved to be indeed 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, dubbing 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, it quickly began to spring leaks as the boat slowly melted. At twenty minutes in with the boat deteriorating, the experiment was pulled, and 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 predicted that an entire aircraft carrier could be built out of pykrete. [READ THE REST OF THIS ARTICLE]





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