In this series of articles, Concrete Week will explore the impact of the material on our environment and us, and look at alternative options for the future. The Romans used it in everything from bath houses to harbours, aqueducts to the Colosseum, systematising its production and application from the third century BC to the fall of the empire in the fifth century AD. Unlike modern reinforced concrete — which can last about a hundred years without major repairs or replacement — many Roman concrete structures are still with us many centuries later.
The key to its longevity appears to be the use of volcanic ash, or pozzolana. Where modern concrete is a mix of lime-based cement, water, sand and an aggregate such as gravel, the recipe for concrete set down by architect Vitruvius in the first century BC involved pozzolana and chunks of volcanic rock, known as tuff.
When it comes to Roman marine concrete, used to construct piers and breakwaters, research published in found that the addition of sea water actually strengthened these structures over time, making them harder and harder over the millennia.
It still looks strikingly modern today and it remains the largest non-reinforced concrete dome in the world, 19 centuries after it was built. With only a couple of isolated exceptions , around 1, years passed after the fall of the western Roman empire until concrete was used again on any great scale. The invention of reinforced concrete gave the material a new life. It was pioneered in France in the midth century, but was popularised by California-based engineer Ernest Ransome, who poured over iron and later steel bars to improving its tensile strength.
The first reinforced concrete skyscraper, the Ingalls Building in Cincinnati; underneath the first reinforced concrete bridge, Golden Gate Park, San Francisco. Concrete lasts well compared with asphalt roads, which are made using bitumen, and it was widely used throughout the US interstate highway system.
Isaac Johnson claims to have burned the raw materials of portland cement to clinkering temperatures. David Saylor was issued the first American patent for portland cement. He showed the importance of true clinkering. Grant of England show the importance of using the hardest and densest portions of the clinker.
Key ingredients were being chemically analyzed. Henri Le Chatelier of France established oxide ratios to prepare the proper amount of lime to produce portland cement.
He named the components: Alite tricalcium silicate , Belite dicalcium silicate , and Celite tetracalcium aluminoferrite. He proposed that hardening is caused by the formation of crystalline products of the reaction between cement and water.
The addition of gypsum when grinding clinker to act as a retardant to the setting of concrete was introduced in the USA. Vertical shaft kilns were replaced with rotary kilns and ball mills were used for grinding cement. It still exists today! William Michaelis claimed that hydrated metasilicates form a gelatinous mass gel that dehydrates over time to harden. Linus Pauling of the USA formulated a set of principles for the structures of complex silicates.
They still exist today! CN Tower in Toronto, Canada, the tallest slip-form building, was constructed. Joseph Aspdin of England is credited with the invention of modern Portland cement. He named his cement Portland, after a rock quary that produced very strong stone.
In , the first test of tensile and compressive strength took place in Germany. Tensile strength refers to concrete's ability to resist tension, or pulling apart forces. Compressive strength refers to concrete's ability to resist compression, or pushing together forces.
Both tensile and compressive strength are expressed in pounds per square inch psi. This bridge was the first reinforced concrete bridge, and it still exists today, over one hundred years after it was built! In , the first concrete street in American was built in Bellefontaine, Ohio. This is a modern photo of the historic street. Today, pervious concrete is being advocated as the best, and most environmentally friendly, surface for streets. The first concrete high rise was built in Cincinnati, Ohio, in The Ingalls Building, as it is called, has sixteen stories, making it one of the great engineering feats of its time.
These homes still exist today. Edison envisioned that his design would meet great success, and that before no time everyone in America would be living in a concrete home. However, his vision did not become a reality as soon as he expected; in fact, concrete homes are just starting to gain popularity now, one hundred years later. It was the most superior cement of the time, producing greater strengths than were previously possible. The mass production of this cement began in and the concrete explosion began.
The use of concrete in Ireland can be traced as far back as , in the foundations of a bridge crossing the River Glyde, in Dundalk. As the benefits of this material were realised, concrete was increasingly used as a solution to construction problems. Other examples of milestones in Irish concrete use are- the Dublin Port extension built from under the supervision of engineer Bindon Stoney, widely regarded as the father of concrete in Ireland, Mizen Head Footbridge, a reinforced concrete arch built in and Ardnacrusha Dam, opened in , the first structure to use watertight concrete.
A key to the consistent and economic supply of concrete in a country is its ability to produce, rather than import cement.
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