![]() ![]() Once the process completes, the concrete sets. Over the course of several days, the tendrils harden, locking the mixture in place. These tendrils enmesh any particles of aggregate suspended between them. After 3 or 4 hours, the gel releases microscopic tendrils from each grain of cement. The two create a gelatinous mass that suspends any material mixed into them. Water: This is the catalyst that creates the reaction.Ĭoncrete forms from a complex reaction that starts when water mixes with cement.Air: Concrete must have air pockets in them to ease expansion and contraction.Taken together, coarse and fine aggregates make up the bulk of the concrete’s mass at up to 70 percent. Fine aggregate: These are fine-grained substances like sand that add bulk to the finished concrete.The most common aggregates include crushed stones and gravel. Coarse aggregate: These are large lumps that add volume and weight to the concrete mixture.Other available materials for binding include lime and volcanic ash. Today, the binding mixture of choice is Portland cement. The resulting slurry hardens and traps the remaining ingredients together, creating concrete. Binding mixture (cement): This is a reactive substance that solidifies when mixed with water.To create concrete, builders must mix five essential ingredients: Closer inspection will reveal its true nature as a composite material. The raw material for concrete comes from sedimentary rocks. To the untrained eye, a piece of broken concrete resembles stone. Across the globe, concrete remains a key component in infrastructure and domestic construction. Though first perfected by the Romans, it’s become synonymous with modernity. With it, builders create imposing and beautiful marvels of engineering. There’s little wonder why we call the modern city “the concrete jungle.”Ĭoncrete is a miracle of chemistry. Concrete bridges, sidewalks, and roads link up the world. Many buildings themselves are built in part of concrete. In every town and city today, you’re bound to see at least one thing made of the substance. Ubiquitous concrete lies at the foundation of modern society, in the most literal way. Concrete: Laying the Groundwork for the Modern World ![]()
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