Ancient Concrete
The fountain in the center of the
courtyard is concrete
(This is from the Palace
of Domitian in Rome)
Concrete is a kind of man-made stone. You make it by mixing lime and clay and sand and gravel and water. Lime is basically the ashes of limestone; it's what you get when you burn limestone or marble. Lime and clay and water mixed make cement, and then you mix the cement with sand and gravel to make concrete.
The Egyptians, Mesopotamians, and Greeks knew how to make concrete but they didn't use it very much. The Romans began to use a lot of concrete in their buildings about the time of the Emperor Nero, 60 AD, and they used it more and more from then on, usually with a brick facing to cover it and make it look prettier.
You can make reinforced concrete by putting metal rods inside the concrete. This makes it a lot stronger. Most concrete buildings today are reinforced with steel. The Romans were the first to use reinforced concrete, mainly in aqueducts.
After the fall of Rome, neither the Islamic Empire nor the European kingdoms used as much concrete as the Romans had. They preferred to build in stone.
To find out more about concrete, check out this book from Amazon.com or from your library:
Ancient Science: 40 Time-Traveling, World-Exploring, History-Making Activities for Kids, by Jim Wiese (2003).
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