Concrete

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Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid. It is the second-most-used substance (after water), the most widely used building material, and the most-manufactured material in the world. Cement-bound concrete differs from the less rigid, less durable asphaltic concrete, which has a bituminous binder. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that can be poured and molded into shape. The cement reacts with the water through a process called hydration, which hardens it after several hours to form a solid matrix that binds the materials together into a durable stone-like material with various uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process is exothermic, which means that ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans...

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