When was concrete invented by the romans

The precursor to concrete was invented in about BC when Middle Eastern builders found that when they coated the outsides of their pounded-clay fortresses and home walls with a thin, damp coating of burned limestone, it reacted chemically with gases in the air to form a hard, protective surface. Roman concrete, also called opus caementicium, was a material used in construction in Ancient Rome. Roman concrete was based on a hydraulic-setting cement. It is durable due to its incorporation of pozzolanic ash, which prevents cracks from spreading.

The ancient Romans mastered concrete more than 2, years ago and used it to build piers, breakwaters, and other structures. She explains that for ancient concrete makers, the first step was to mix volcanic ash with lime and water — fresh water for architectural monuments, and seawater for marine concrete. Ancient Romans built concrete sea walls that have withstood pounding ocean waves for more than 2, years. Saltwater corrodes modern concrete within years. The concrete is made of quicklime, or calcium oxide, and volcanic ash.

Yet structures like the Pantheon and the Colosseum have survived for centuries, often with little to no maintenance. Geologists, archaeologists and engineers are studying the properties of ancient Roman concrete to solve the mystery of its longevity. Modern concrete is a mix of a lime-based cement, water, sand and so-called aggregates such as fine gravel. The formula for Roman concrete also starts with limestone: builders burned it to produce quicklime and then added water to create a paste. Next they mixed in volcanic ash—usually three parts volcanic ash to one part lime, according to the writings of Vitruvius, a first-century B.

The volcanic ash reacted with the lime paste to create a durable mortar that was combined with fist-size chunks of bricks or volcanic rocks called tuff, and then packed into place to form structures like walls or vaults.

However, that volume predates the construction of the Pantheon by about years. It took about a thousand years for concrete to make a comeback. Europe went through the Dark Ages, and ancient Roman texts were not rediscovered until the Renaissance. Renaissance engineers studied Vitruvius's On Architecture , but with no knowledge of the mysterious gray building material, scholars had a tough time deciphering Vitruvius' terminology. Only an Italian friar named Giovanni Giocondo was able to crack the code.

Giocondo was trained in archaeology and architecture, and he noticed something impressive about caementis. Its resistance to weathering suggested it must be hydraulic, meaning it hardens under water. Concrete, Giocondo thought, must be replicated.

And so Giocondo built structures that mixed lime and pozzolana, as Vitruvius instructed. His first attempt was the original Pont Notre-Dame Bridge. Houses were built atop the bridge , but about years after the structure was completed, the entire thing was demolished. The houses put too much stress on this primitive version of concrete, and Giocondo's efforts would go down in history as the only attempt to create concrete during the Renaissance. But bigger breakthroughs were on the horizon.

In the 16th century, trass—a volcanic ash similar to pozzolana—was discovered as a useful material for making tools in Andernach, Germany. A bricklayer tried using the ash in lime mortar, a mixture quite similar to concrete , and learned that the resulting material was stronger and water resistant. The result was a chain reaction that led to the creation of modern cement. In the 17th century, the Dutch began selling trass to France and Britain. The trass was used for buildings that required hydraulic properties.

In constant conflict and competition, France and Britain began efforts to create their own hydraulic building materials. The British had the advantage, though.

They had John Smeaton. Smeaton is known as the father of civil engineering. He created a formula for air pressure's effect on an object's velocity, which contains the " Smeaton Coefficient. In the mids, Smeaton was commissioned to build a lighthouse on a troublesome perch on the Eddystone Rocks, just off the southern coast of England. Three lighthouses on the site had all been destroyed. One couldn't survive the winter. The second collapsed during a hurricane.

The last, which had a wooden interior, caught fire from the light and burned to the ground. Smeaton, up to the challenge, was determined to build the strongest lighthouse in the world. The English civil engineer experimented with known hydraulic materials. He rolled up balls of lime the cooked version of limestone and trass and dropped them into boiling water.

The lime on its own dissolved, but the lime that came into contact with trass endured. Smeaton then tested limestone from a town called Aberthaw, dropping it into water and a nitric acid solution used to separate minerals.

The experiment revealed that about a tenth of the limestone from Aberthaw contained clay. Smeaton took note of the high strength of this limestone-clay conglomerate. Today we call the same material natural cement. The lighthouse was constructed between and using Smeaton's hydraulic cement-filled mortar. It stood on the Eddystone Rocks for more than a century before the rocks began to erode.

In , the lighthouse was disassembled and rebuilt in Plymouth, England. Every businessman in Britain wanted to capitalize on the new building material. For marketing purposes, manufacturers started referring to their natural cement as "Roman cement. Joseph Aspdin was a bricklayer from Leeds, England. In the s, he would walk to the paved roads of town and steal bricks of limestone.

He was fined twice, but that didn't stop the limestone thief from making off with the bricks for his materials science tests. The historical record is a little spotty, but we know that Aspdin managed to invent his own cement mixture.

He named it "Portland cement" after the limestone-clad Isle of Portland. Like the term "Roman cement," the name "Portland cement" became a marketing scheme. But Joseph Aspdin was not the con man—his son William was. Around this time there was a common engineering practice called slurry mixing, in which powdered but un-kilned limestone was mixed with clay and water.

The concoction turned into a paste. The paste was then kilned into a solid and crushed, turning it into cement powder. If the paste was kilned too long, the resulting material, called "clinker," was generally thrown out.

William Aspdin decided he'd test the unwanted scraps of clinker. As a young man, William left his father to find his own way in London. He began taking the clinker off cement makers' hands.

He had no employees, no kiln. All he did was whack the clinker with a hammer to break it down. Once clinker was mixed with the other cement materials, the result was a new cement that, years later, an independent firm would confirm to be twice as strong as "Roman cement.

William Aspdin had created a cement that was better than the rest, and yet he proceeded to find investors who knew nothing about the cement industry, egregiously lie about his product to the public, swindle his partners, and start all over again.

In a circular for his first cement firm, William set out to establish the validity of his unproven product. He wrote that his cement had been around for years in Northern England, fraudulently claiming his own "Portland cement" was the same recipe his father had developed.

William's firm managed to buy out another cement factory, yet within a year the company went bankrupt. William found new inexperienced investors and began a new firm using one of his previous factories. He published more lies. This time he claimed that his father's Portland cement had been around since , and that it was used in one of England's most grueling construction projects: the Thames Tunnel.

To make their concrete, Romans used much less lime, and made it from limestone baked at degrees Celsius 1, degrees Fahrenheit or lower, a process that used up much less fuel. Monteiro and his colleagues also suggest that adopting materials and production techniques used by the ancient Romans could produce longer-lasting concrete that generates less carbon dioxide.

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