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Full Version: The Principles of Building Indestructible Sand Castles
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EXCERPT: If you had a formal education that touched even a little bit of composite materials in the course, you will immediately be able to recall what these amazing materials can do. For others, Composite materials, as the name suggests, are materials that are composed of two or more different kinds of materials.

In a simple case think of your body, which is, in a broad sense, a combination of skin material and bone material. These materials are designed to take advantage of the contrasting properties of, say two different materials. For simplicity’s sake, skin is soft and bone is hard. The bone gives body a solid structure, while the skin and muscle tissues enables this hard skeleton to make fluid movements – flex or bend – and still be together.

Individually the materials that make up a composite material are not very capable. But when they come together, composite materials can blow your mind. To appreciate how this simple coming together of two humble materials can create a super material, and to appreciate the mind blowing properties it can have, let us first look at what most of us have heard of – “Carbon Fiber”. We will get into the more mind bending aspect of composites after that....

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[...] If you take a handful of sand and try to make a block out of it, you probably won’t even be able to make it. All you’ll accomplish doing is making a conical heap of sand. We all know, sand can’t hold its structure under its own weight. The individual particles of sand aren’t held together by anything. You may succeed in constructing something that looks like a block if you try to bind it by using a little amount of water. That is what little kids do at the beach to make weak castles of sand. Whatever you do, your block (or castle) won’t be able to bear a lot of weight that you put on it. If you try to stand on it, the block would not be able to support your weight without collapsing into a heap of sand.

After this try a simple experiment. Lay down an inch of sand, put a sheet of paper on it and then again a layer of sand and paper and so on – A similar process to that of making a CFRP we saw above. After a couple of sheets, say 15 sheets of paper and 15 inches of sand you will have a decently thick block of sand in front of you. You can probably even stand on it without destroying the block. It is amazing how much difference just 15 sheets of paper can make. Enough number of sheets can even support the weight of a big car....