Transparent Concrete [1]: \"That is...

Transparent Concrete: "That is not as crazy as it sounds. Technically, concrete is simply a mixture of three ingredients: big lumps of material called the coarse aggregate (such as gravel), smaller lumps called the fine aggregate (such as sand) and a binding agent, or cement, to glue it all together into a solid. So translucent concrete, in theory, should be fairly easy to make using bits of plastic or glass of various sizes, with some kind of transparent glue to act as a binding agent."