Some of The Great Wall Was Made Out of Rice! скачать в хорошем качестве

Some of The Great Wall Was Made Out of Rice!

The Great Wall of China isn't just one long wall as its name suggests, it is actually a combination of wall sections, trenches, fortifications, and individual buildings and was built by various different rulers over a period of around 2000 years. If you include all the trenches and broken sections of the wall, The Great wall is over 13,000 miles long, but if you are just counting solid wall it's about 1700 miles, but still, that is incredibly long, so long in fact, that is can be seen from space! Or can it? Well, that actually depends on where you think space starts. Officially, space starts at 100km above sea level, and at this height, if the sun is at the right angle and casting shadows, you can see The Great Wall with your naked eye. However, the International Space Station orbits at between 330 and 410 km above sea level and from here, it's impossible to see the wall without the use of a telescope. The Great Wall that we know and have seen in photos and on documentaries are the sections built with bricks and mortar and these sections were built during the Ming Dynasty between 1368 and 1644. To try to understand the secrets of its strength and longevity, scientists at Zhejiang University analyzed samples of mortar taken from a 600-year-old section of the wall in Nanjing. What they found was that the mortar had been made by combining a sticky rice soup with powdered lime. This discovery alone wasn't particularly surprising considering the importance of rice in the Chinese diet and therefore its abundance. What was surprising were the physical and mechanical properties the sticky rice gave the mortar. Using a scanning electron microscope and chemical analysis they found that the addition of rice's amylopectin to lime's calcium carbonate created smaller calcium carbonate crystals producing a more tightly bonded mixture that was more likely to hold its shape over time and more water-resistant. In addition to this, key chemical reactions within the mortar continued to occur making it become stronger over time and exceptionally good at controlling shrinkage. Using this research they have been able to determine the building's specific mortar recipe and then reproduce it for use in conservation work. This rice mortar has since been used successfully in conservation work carried out on the 800-year-old Shouchang bridge in eastern China. Please give us a like and subscribe! If you enjoyed the video please let us know in the comments below! Get more Tips here! http://www.destinationtips.com