when was concrete,as we know it,first used?

Answer 1

The Assyrians and Babylonians used clay as cement in their concrete. The Egyptians used lime and gypsum cement. In the Roman Empire, concrete made from quicklime, pozzolanic ash / pozzolana and an aggregate made from pumice was very similar to modern Portland cement concrete. In 1756, the British engineer John Smeaton pioneered the use of Portland cement in concrete, using pebbles and powdered brick as aggregate. In modern times the use of recycled materials as concrete ingredients is gaining popularity because of increasingly stringent environmental legislation. The most conspicuous of these is fly ash, a by product of coal fired power plants. This has a significant impact by reducing the amount of quarrying and landfill space required.

The properties of concrete have been altered since Roman and Egyptian times, when it was discovered that adding volcanic ash to the mix allowed it to set under water. Similarly, the Romans knew that adding horse hair made concrete less liable to shrink while it hardened, and adding blood made it more frost resistant. In modern times researchers have added other materials to create concrete that is extremely strong, and even concrete that can conduct electricity.

Portland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar and plaster. English engineer Joseph Aspdin patented Portland cement in 1824, and it was named after the limestone cliffs on the Isle of Portland in England because its color is similar to the stone quarried there.

Answer 2

Concrete was first invented by the Romans who used the concrete as walls. They used this to make structures sturdier.

Answer 3

It was first used in the roman era, it revolutionized architecture making the arch possible

Answer 4

http://en.wikipedia.org/wiki/Concrete

Answer 5

Depends on what you mean by "as we know it". I don't think they started using rebar until the early 20th century if that is what you mean.

Answer 6

Didn't the Romans invent it?