Concrete

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Invented by : John Smeaton
Invented in year : 1756

Concrete is a construction material composed of cement (commonly Portland cement) as well as other materials such as fly ash and slag cement, aggregate (generally gravel, limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures.Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material. Concrete is used to make pavements, pipe, architectural structures, foundations, motorways / roads, bridges / overpasses, parking structures, brick/block walls and footings for gates, fences and poles. Cement has been a naturally occurring substance for more than 12 million years and was used in rudimentary forms from about 3000 BC by the Egyptians, Chinese and Greeks.

History of the Invention

In man-made form, however, concrete was first developed by the Romans and was used for building bridges, roads and buildings. Some time in the third century BC, they discovered that mixing volcanic ash with lime mortar, sand and gravel made a rock-hard substance similar to today's concrete. With the addition of animal fat, milk and blood, this substance was called pozzolan cement and was used to construct the Appian Way, the Coliseum and the Pantheon, as well as the Pont du Gard in Southern France. Some of those early concrete structures remain, giving testament to the durability of the concrete and cement developed by the Romans. The Romans used lime and volcanic ash to create their cement.

After the fall of the Roman Empire in the A.D. 400's, the art of making cement was lost. It was 13 centuries later, in 1756 that the British engineer, John Smeaton pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. John Smeaton was commissioned by parliament to rebuild the Eddystone Lighthouse, off the coast of Cornwall, England. The lighthouse needed to be permanent so that it could last all sorts of weather conditions. Smeaton started looking for a building material that would not be adversely affected by water. Smeaton experimented with a number of limes and pozzolans, tested both in salt and fresh waters to disintegration. Through his experiment he discovered in 1774, that quicklime made a harder cement. In 1793 he took that discovery another step forward when he realized that the calcinations of limestone that contained clay produced hydraulic lime, a lime that hardens under water. It was this material that was used in the historic rebuilding of the Eddystone Lighthouse in Cornwall, England.

Development in the Invention of Concrete

Smeaton's work led to a more widespread use of concrete throughout England and further advances in technology. James Parker patented a natural hydraulic cement in 1796 that was made by calcinating pieces of pure limestone that contained clay The debut for cement in the United States occurred in 1818, with the construction of the Erie Canal. During this time, American Engineer, Canvass White, discovered a rock in New York's Madison County, which made natural hydraulic cement with minimal processing.

In 1824, British bricklayer Joseph Aspdin invented Portland cement, which was considered superior to natural cement. It was created with a combination of limestone and clay. The burning process changed the chemical properties of the materials and Joseph Aspdin created a stronger cement than what using plain crushed limestone would produce. Portland Cement remained the dominant cement used in concrete production.

Concrete that includes embedded metal (usually steel) is called Reinforced Concrete or Ferroconcrete. Reinforced concrete was invented (1849) by Joseph Monier, who received a patent in 1867. Joseph Monier was a Parisian gardener who made garden pots and tubs of concrete reinforced with an iron mesh. Reinforced concrete combines the tensile or bendable strength of metal and the compressional strength of concrete to withstand heavy loads. Joseph Monier exhibited his invention at the Paris Exposition of 1867. Besides his pots and tubs, Joseph Monier promoted reinforced concrete for use in railway ties, pipes, floors, arches, and bridges

French engineer, Eugene Freyssinet, invented pre-stressed concrete in 1927. Pre-stressed is used to make structures, such as bridges or beams, which have a longer span. It is made by casting concrete around steel cables that have been stretched. When the concrete hardens the cables compress the concrete.

Role of Concrete in the Improvement Of Human Life

• It made buildings more strong and durable as compared to earlier.

• The invention itself became a source of business for those who manufactured it.

• It's invention inspired more superior technology and techniques which changed the way construction was implemented.